JPH11310416A - Cathodic substance of lithium ion secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lithium ion secondary battery cathodic substance having a cycling stability, high charging electric voltage resistance and high energy density of a secondary battery having a lithium cathode substance. SOLUTION: A proper amount of a selected divalent cation is added to a lithiated transition metal oxide having a rhombohedral R-3m crystal structure to allow all or a part of the divalent cation to occupy crystal lattices in the crystal structure of a transition metal atom layer. The lithiated transition metal oxide can be used as the cathodic substance of a lithium ion secondary battery. The substance includes an Li1+x Ni1+y My Nx O2(1+ X) and Li1 Ni1-y My Nx Op without limited to the compounds. Therein, the transition metal is selected from titanium, vanadium, chromium, manganese, cobalt and aluminum. N is the element of the group II in the periodic table, and is selected from magnesium, calcium, strontium, barium and zinc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a negative electrode material of a battery. In particular, the present invention relates to a lithium transition metal oxide negative electrode material having a rhombohedral R-3m crystal structure and doped with at least one positive ion belonging to Group II of the periodic table. It is. The negative electrode material according to the present invention exhibits durability to high capacity and voltage and fading of suppressed specific capacity in one cycle of discharge and charge cycles.

[0002]

BACKGROUND OF THE INVENTION At present, the demand for improved rechargeable batteries is steadily increasing to meet the ever-increasing demand for portable computers, cellular telephones and portable electronic appliances. A rechargeable battery is also called a secondary battery and basically includes a negative electrode, a positive electrode, a liquid electrolyte interposed between the negative electrode and the positive electrode, or other substances,
In addition, it allows the movement of ions between the negative electrode and the positive electrode. The performance requirements for rechargeable batteries are high capacity, good cyclability, and high resistance to voltage.

[0003] The capacity of a rechargeable battery is measured in units of mAh / g, which is the charge that a unit weight of substance can produce. The cyclability of a rechargeable battery is also known as "cycling" or "cycle life" and is a measure of battery capacity reduction or fading rate over a course of one discharge-recharge cycle. Recyclability may be represented as the average percentage of reduced capacity over a specified discharge-recharge cycle course. High cyclability is a direct determination of the useful life of a battery, and is particularly important when the final cost of production and consumption of the battery is high. The voltage endurance of a rechargeable battery is typically measured in volts and is represented as the maximum limit of the voltage that the battery can charge without damaging the integrity of the negative electrode material structure. Therefore, a battery having a relatively high voltage durability exhibits good capacity fading properties when charged to a high voltage or when charged to a low voltage. Batteries charged to high voltages can produce high capacity and energy density, so higher voltage durability is desirable for batteries. The energy density of a battery is the net (net) energy of the battery that can be released by the unit weight of the active anode material during the discharging process. The net energy is expressed as a product of charge and voltage per unit weight of the material, wherein; E = (1 / M) ∫ φ
Calculated by V (q) dq, when N is strontium, zinc or barium, 0 ≦ z ≦ 0.1.
In the above equation, M is the weight of the negative electrode active material, Q is the net charge after discharge, and V (q) is the voltage expressed as a function of q. A constant weight battery containing a high energy density emits higher energy in a given application range, so it is desirable to have a high energy density.

[0004] Increasing commercial demands in the market for rechargeable batteries include improvements in existing properties, which are substantial advantages over current batteries.
Therefore, improvements to rechargeable battery anode materials
Actively being continued.

[0005] Lithium-ion rechargeable batteries, which belong to the family of rechargeable batteries, contain a lithium-based crystalline material as a negative electrode. The crystal lattice of the negative electrode material provides the lithium ion with a structural framework. Lithium ions can be inserted into or removed from the negative electrode crystal framework. Therefore, the negative electrode material is seen as an "active" material in a lithium ion rechargeable battery. During charging, lithium ions are displaced from the anode material and are deposited or intercarated in the cathode (depending on the configuration of the cathode). During discharge, lithium ions return into the negative electrode material and intercalate, facilitating the flow of electricity between battery terminals. During the charge and discharge cycle, the negative electrode containing the active material
No significant structural changes are allowed to preserve the reversibility of the reaction. The reversibility of the reaction during the discharge is allowed, and the lithium ions are repeatedly returned into the negative electrode material and can be intercalated due to the stability of the crystal structure of the negative electrode material. It must be noted that the performance of the battery depends greatly on the components of the negative electrode material. It also directly affects the specific capacity, energy density, current capacity and recyclability of the battery.

[0006] The group of lithium ion batteries includes those in which the negative electrode comprises a lithium transition metal oxide component. Generally, lithium manganese oxide spinel (LiMn ₂ O _{4 having} a spinel skeleton structure), lithium nickel oxide (LiNiO ₂ ), and lithium cobalt
Oxide (LiCoO ₂ ) and the like. All of these materials operate by reversible lithium ion transfer as described above. During the recycling of the discharge, the lithium ions are transferred from the negative electrode and are deposited or intercalated on the positive electrode, and hardly impair the original structure of the negative electrode. During discharge, lithium ions immediately return to the negative electrode and intercalate. Conventional lithium transition metal oxides exhibit a high voltage (up to 3.8-4 V) and a high energy density for lithium. This is due to the small molecular weight.

Table 1 lists the energy densities of the negative electrode materials of LiMn ₂ O ₄ , LiNiO ₂ and LiCoO ₂ . Cork is used for the positive electrode, which is k. Brandt's Soli
d Reprinted from State Ionics 69 (1994), pp. 173-183. Table 1 also shows the recyclability,
Based on the manufacturing cost and technologies commonly used in battery manufacturing technology, the degree of difficulty in synthesizing substances was also ranked.

[0008]

[Table 1]

Among the three substances, LiMn ₂ O ₄ and LiN
The production cost of iO ₂ is obviously low, and the impact on environmental pollution is lighter than that of LiCoO ₂ . However, LiMn ₂
O ₄ and the inconsistency of recycling act of LiNiO ₂ is, to limit these applications today. If LiMn ₂ O ₄ and LiN
If the recyclability of iO ₂ can be improved, this material can be used as a negative electrode material of a lithium ion rechargeable battery.
It cannot be said that there is no possibility of replacing CoO ₂ .

[0010] derived from a lithium transition metal oxide,
As a method of improving the stability of recyclability, an element other than those listed in the periodic table is added. In one example, for example, an undoped compound, LiMn ₂ O
_4. The change in the crystal structure indicated by the numerical value of LiNiO ₂ and LiCoO _{2 in} the chemical calculation showed that the result improved the electrochemical properties of the substance.

RJ Gummow et al, Solid State Ioni
c (69), “Improved Capa,” listed on pages 59-67.
city Retention in Rechargeable 4v Lithium / Lithium-
The Manganese Oxide (Spinel) Cell "suggests that an appropriate amount of lithium can be added to LiMn ₂ O ₄ to enhance the cycling behavior of the material.
It also suggests that adding magnesium or zinc to LiMn ₂ O ₄ and substituting some of the magnesium would improve cycling behavior. In any case, although the stability of the cycling property of the substance is improved, the specific capacity of the spinel substance of LiMn ₂ O ₄ doped with magnesium or zinc is small, and is 90 to 105 mA.
h / g.

The entire contents disclosed in US Pat. No. 5,264,201 are disclosed herein. According to this, the material with improved cycling stability is of the formula Li _x Ni
_ZXY M _y O in the representative, among which x is about 0.8 and 1.0
In between, M is one or more of cobalt, iron, titanium, manganese, chromium
ium) and vanadium, y ≦ 0.2,
However, it is assumed that y ≦ 0.5 for cobalt. Pure L
In the case of iNiO ₂ , substantially pure lithium and substantially pure nickel metal atomic layers alternate between the substantially pure oxygen layers. When the lithium calculated by the chemical calculation decreases below 0.1, the nickel atoms enter the lithium atomic layer and the intercalation of lithium atoms decreases (de
intercalation). US Patent No. 5,26
The inventor of the 4,201 patent suggests that if x is kept in the above range, the amount of nickel atoms will not be substantially mixed in to reduce the ability of lithium to intercalate day. Although different chemical computational substitutions and adjustments as suggested by the patent in US Pat. No. 5,264,201 show some improvement over pure LiNiO ₂ material, the improved material is still LiCoO _2. It is not sufficient to provide stability of the cyclability of the substance. Also, the material of the patent of US Pat. No. 5,264,201,
It does not have remarkable voltage durability performance. Especially when it comes to applicability.

The contents disclosed in US Pat. No. 5,591,543 will be fully disclosed herein for reference. According to this, in the group of lithium ion anode materials synthesized by Li _1-x Q _{x / 2} ZO _m , Z is one transition metal selected from cobalt, nickel, manganese, iron, vanadium and the like, and Q is Calcium, magnesium, strontium (Stro) selected from the group II elements of the periodic table
ntium) and barium, where m is 2 or 2.5
Depending on the identity of Z. US Patent No. 5,591,543
According to the inventor of the patent, the addition of the oxide or carbonate compound of the element Q during the synthesis is such that the Q ⁺² positive ions are combined in the lithium crystal lattice in the LiCoO ₂ lattice, and the remaining QO
Alternatively, it states that the QCO ₃ compound is mixed as it is in the completed negative electrode. During cycling, the dissolving action of oxides and carbonates of Group II of the periodic table acts as a buffering action for the electrolyte, and water and acid impurities (acid im) in the electrolytic solution.
Reacts with purities) and acts as a desiccant. The inventor of the U.S. Patent No. 5,591,543 appears to have attributed the improved recyclability of the material to the drying action of Group II oxides and carbonates.

As shown in FIGS. 4, 6 and 8 of the patent of US Pat. No. 5,591,543, a secondary battery using the material disclosed in the invention for a negative electrode can charge up to 4.2V. And This leaves the need to develop lithium transition metal oxide anode materials that can withstand higher charging voltages. First, a material that can be charged at a voltage of 4.2 V or higher must have higher capacity and energy density. As explained above, such enhanced performance offers significant benefits in applications. In addition, a recent negative electrode material having a R3m (herein, denoted as R-3m) crystal structure has a 4.2-4.3V
It becomes unstable when charged with the above voltage. During charging (range 4.2-4.3V), when the concentration of lithium content in the anode material dilutes to a certain value, a structural change occurs in the material, which is the fading characteristics of these materials. Deteriorates. Therefore, the ability of the negative electrode material to withstand a charge of about 4.2 V is one of the important characteristics. If the anode material can withstand higher voltage repetitive charging compared to conventional anode materials, this improved material can provide higher capacity when discharged.

[0015] Therefore, the above-mentioned invention, or the improvement of cycling stability and other electrochemical properties, which are the result of research on the structure of a secondary battery in recent years, are still considered, and the lithium ion More effort will be needed regarding cycling stability, higher withstand voltage or other improvements in electrochemical properties, and so on.

[0016]

SUMMARY OF THE INVENTION The present invention relates to a cycling stability of a secondary battery having a lithium ion anode material,
A lithium-transition metal oxide anode material having a rhombohedral R-3m crystal structure is intended to have a high withstand voltage, a high energy density, and other electrochemical properties. Doping by the addition of positive ions belonging to

[0017]

The present invention for achieving the above object is constituted as follows for each claim.

The invention according to claim 1 includes lithium, oxygen and at least one transition metal, and further comprises a crystalline material (that is, a crystalline material, which is a crystalline material in English). The same is true in the present specification.) This is a crystalline substance characterized by containing a divalent positive ion that mainly occupies a crystal lattice to be occupied by the transition metal atom.

The invention according to claim 2 is characterized in that the crystalline substance mainly has a single-form R-3m crystal structure when the divalent cation is not present. The crystalline substance described in (1).

The invention according to claim 3 is the crystalline material according to claim 2, wherein a part of the lithium can be reversibly removed from the crystal structure.

The invention according to claim 4 is characterized in that the divalent cation in the transition metal layer promotes the oxidation state of the transition metal ion in the substance. It is a crystalline substance.

According to a fifth aspect of the present invention, the ratio of the presence of the divalent positive ions is determined based on the total number of atoms in the crystal layer of the substance mainly occupied by the transition metal atoms.
The crystalline substance according to claim 3, wherein the content is about 25%.

According to the invention described in claim 6, the ratio is 3
The crystalline material according to claim 5, wherein the atomic number ratio is up to 15%.

The invention according to claim 7 is the crystal according to claim 3, wherein the divalent positive ion is one or more ions of an element of Group II of the periodic table. Substance.

[0025] The invention according to claim 8 is characterized in that the periodic table II
8. The crystalline substance according to claim 7, wherein the group III element is an alkaline earth metal element and zinc.

A ninth aspect of the present invention is the crystalline material according to the eighth aspect, wherein the alkaline earth metal element is magnesium, calcium, strontium and barium.

According to a tenth aspect of the present invention, the transition metal is selected from one or more of titanium, vanadium, chromium, manganese, iron, cobalt and aluminum. A crystalline substance according to claim 3.

[0028] The invention according to claim 11 is characterized in that the composition Li _{1 + x}
Has a _{Ni 1-y M y N z} O p, in the composition, M is titanium,
Selected from vanadium, chromium, manganese, iron, cobalt and aluminum; N selected from magnesium, calcium, strontium, barium and zinc; 0 ≦ x ≦ z; 2 (1 + z / 2) ≦ p ≦ 2 (1 + z); When M is cobalt or manganese, 0 ≦ y ≦ 1;
When M is titanium, vanadium, chromium or iron,
0 ≦ y ≦ 0.25; when M is aluminum, y ≦
0.4; when N is magnesium or calcium, 0 ≦ z ≦ 0.25; and when N is strontium, zinc or barium, 0 ≦ z ≦ 0.1; 2. The crystalline substance according to 1.

The invention according to claim 12 is characterized in that the composition Li _{1 + x
Ni 1-y M y N x} O 2 having a _{(1 + x),} in said composition, M is selected from titanium, vanadium, chromium, manganese, iron, cobalt and aluminum; N are magnesium, calcium, Selected from strontium, barium and zinc; when M is cobalt or manganese, 0 ≦ y
≦ 1; when M is titanium, vanadium, chromium or iron, 0 ≦ y ≦ 0.5; when M is aluminum,
y ≦ 0.4; when N is magnesium or calcium, 0 ≦ x ≦ 0.25; when N is strontium, barium or zinc, 0 ≦ x ≦ 0.1; A crystalline substance according to claim 11.

According to a thirteenth aspect of the present invention, the composition Li ₁ N
i has a _{1-y M y N x O} p, in the composition, M is titanium, vanadium, chromium, manganese, iron, selected from cobalt and aluminum; N are magnesium, calcium, strontium, barium and zinc Chosen;
When M is cobalt or manganese, 0 ≦ y ≦ 1;
When M is titanium, vanadium, chromium or iron,
0 ≦ y ≦ 0.5; when M is aluminum, y ≦
0.4; and when N is magnesium or calcium, 0 ≦ x ≦ 0.25; when N is strontium, barium or zinc, 0 ≦ x ≦ 0.1, and 2
The crystalline substance according to claim 12, wherein (1 + x / 2) ≤p≤2 (1 + x);

According to a fourteenth aspect of the present invention, there is provided an anode for an electrochemical cell, comprising a negative electrode containing the substance according to the first aspect.

According to a fifteenth aspect of the present invention, there is provided the negative electrode according to the fourteenth aspect, comprising the substance according to the eleventh aspect.

According to a sixteenth aspect of the present invention, there is provided the negative electrode according to the fifteenth aspect, comprising the substance according to the twelfth aspect.

According to a seventeenth aspect of the present invention, there is provided the negative electrode according to the fifteenth aspect, comprising the substance according to the thirteenth aspect.

According to an eighteenth aspect of the present invention, there is provided a lithium battery comprising: a negative electrode having the structure according to the fourteenth aspect; a positive electrode compatible with the negative electrode; It is an ion secondary cell.

According to a nineteenth aspect of the present invention, there is provided a lithium ion secondary cell according to the eighteenth aspect, including the negative electrode having the structure of the fifteenth aspect.

According to a twentieth aspect of the present invention, there is provided the lithium ion secondary cell according to the eighteenth aspect, including the negative electrode having the configuration according to the sixteenth aspect.

According to a twenty-first aspect of the present invention, there is provided a lithium ion secondary cell according to the eighteenth aspect, including the negative electrode having the configuration according to the seventeenth aspect.

According to a twenty-second aspect of the present invention, in the manufacturing process, there is provided: Procedure for combining a substance containing at least an amount of lithium, a substance containing an amount of a transition metal, and a substance containing an amount of an atom of at least one Group II element of the Periodic Table, thereby producing a homogeneous solid And b. Heat treating the homogeneous solid to produce an active crystalline lithium transition metal oxide containing an atom of the at least one Group II element of the Periodic Table, wherein the at least one Group II element of the Periodic Table is contained within the active material. A lithium transition comprising selecting the amount of the element so that the atom of the element occupies the crystal lattice occupied mainly by the transition metal atom in the crystal layer of the active material. This is a manufacturing process of a metal oxide crystalline material.

According to a twenty-third aspect of the present invention, the connecting step comprises the steps of: a. Dissolving said amount in at least one solvent to provide a homogeneous solution; b. Drying the homogenous solution to provide the homogenous solid while the solvent is being removed from the homogenous solution by constant agitation.

According to a twenty-fourth aspect of the present invention, the connecting step comprises the steps of: a. Dissolving said amount in at least one solvent to provide a homogeneous solution; b. Spraying the uniform solution into a room through a spray nozzle, maintaining the room temperature at or above the drying temperature of the solvent and evaporating the solvent to provide the uniform solid in powder form. 23. The method according to claim 22, wherein
The process is described in

According to a twenty-fifth aspect of the present invention, in the bonding step, the lithium-containing substance is a substance containing lithium hydroxide, and the bonding step includes the steps of: a. Dissolving said amount of lithium hydroxide and said amount of material comprising a transition metal in one organic solvent to produce a solution containing lithium; b. Preparing an aqueous solution of the substance containing the Group II element of the periodic table; c. Mixing the aqueous solution and the lithium-containing solution together; d. Leaving the mixture to provide a gel until gelation occurs; e. Drying the gel to obtain the homogenous solid.

According to a twenty-sixth aspect of the present invention, the active crystalline lithium transition metal oxide containing the at least one atom of the Group II element of the periodic table has the composition according to the eleventh aspect. A process according to claim 22.

The invention according to claim 27 is characterized in that the active crystalline lithium transition metal oxide containing the at least one atom of a group II element of the periodic table has a composition as defined in claim 12. A process according to claim 26.

The invention according to claim 28 is characterized in that the active crystalline lithium transition metal oxide containing the at least one atom of a group II element of the periodic table has the composition according to claim 13. A process according to claim 26.

According to a twenty-ninth aspect of the present invention, in the manufacturing process, a cell is constituted by a negative electrode having the composition according to the fourteenth aspect, a positive electrode compatible with the negative electrode, and an electrolyte solution compatible with the negative electrode. This is a manufacturing process of the lithium ion secondary cell.

The negative electrode material of the improved secondary battery of the present invention is formed of a lithium transition metal oxide and has a rhombohedral R-
It has a 3 m crystal structure and has added divalent cations. It is a good idea to select from among magnesium, calcium, strontium, barium and zinc as an additive of the divalent cation. Depending on the doping amount of the selected divalent positive ion dopant, all or some of the dopant atoms occupy the crystal lattice to be occupied by the transition metal atoms. The doped lithium transition metal oxide according to the present invention may be a divalent positive ion dopant atom such as, for example, doped lithium nickel oxide, lithium cobalt oxide or lithium nickel cobalt oxide. All or a part of the crystal lattice is occupied by nickel-cobalt, nickel and / or cobalt positive ions, respectively, when they are undoped. The doped lithium transition metal oxide according to the present invention can be formed as a negative electrode of a lithium ion secondary battery. When used for this purpose, high capacity, good recyclability and high voltage resistance (at least up to 4.4 V) can be expected.

Based on research and elucidated facts based on the method and operation according to the present invention, the present inventors have developed a divalent positive ion dopant based on the total number of atoms in the transition metal layer of the crystal lattice. It is believed that when added in the range of about 1 to 25 atom percent, the secondary battery having such a negative electrode material has better electrochemical properties than the secondary battery of the undoped negative electrode material. It is up to no doubt.
Still further improved properties are, as described above, when the divalent cation dopant based on the total number of atoms in the transition metal layer of the crystal lattice is now limited to about 3-15 atom percent. Appear. The present inventors have proposed that a lithium transition metal oxide having a crystal structure of mainly R-3m and not containing a group II dopant of the periodic table, as suggested in the present invention, has a group II dopant of the periodic table. It is concluded that if added, an improvement in its properties can be expected. One or more transition metal atoms added to the particular same and to the substance may be an undoped lithiated transition metal oxide in a single or predominantly single form R-3m crystal structure. Is determined by

The doped lithium transition metal oxides according to the present invention include, but are not necessarily limited to, two groups represented by the following formula: That is, in _{Li 1 + x Ni 1-y} M y N x O (1 + x) ( Equation 1), and _{Li 1 Ni 1-y M y} N x O p ( Equation 2), M is a transition metal One or more of a certain titanium, vanadium, chromium, manganese, iron, cobalt and aluminum; N is one of the group II elements of the periodic table, magnesium, calcium, strontium, barium and zinc When M is cobalt or manganese, 0 ≦ y ≦ 1; M is titanium, vanadium,
0 ≦ y ≦ 0.5 when chromium or iron; y ≦ 0.4 when M is aluminum; 0 <x ≦ 0.25 when N is magnesium or calcium; N is strontium, barium or zinc 0 <x ≦ 0.1; 2 (1 + x / 2) ≦ p ≦ 2 (1 + x) The ranges of the variables x and y are based on observations by the present inventors and various transition metals and divalent metals. The amount of the positive ion added to the parent LiN
Determined based on normal solubility within the iO ₂ structure.

We believe that the doped lithium-nickel transition metal oxide represented by the above two formulas is only a part of the present invention and that all or some It has been discovered that positively charged ions occupy the crystal lattice of the transition metal layer in the crystal. Li according to the invention
_{1 + x Ni 1-y M} y N x O (1 + x) and _{Li 1 Ni 1-y M y} N
Synthesis formula _x O _p substance and U.S. Patent No. 5,591,543
In addition to the obvious differences between the synthesis formulas of Li _1-x Q _{x / 2} ZO _m materials according to the present invention, the presence of divalent cations according to the invention in the transition metal layer is immediately It is distinguished from that of the patent of Patent No. 5,591,543. In the material of the patent of US Pat. No. 5,591,543, alkaline earth dopants
Partially remains in the lithium layer and is partially contained in the negative electrode formed in the form of oxide and carbonate. In addition, the inventors note that the enhanced properties of the material according to the invention are such that divalent cations are present in the crystal lattice of the transition metal compared to that of US Pat. No. 5,591,543. I'm convinced that.

Doping the transition metal crystal lattice with divalent cations according to the present invention results in defective centers in the crystal and increases the number of such defective centers in certain materials of the present invention. To enhance the oxidation state of the transition metal ion. It is well-known that the high voltage endurance and good recyclability of the materials according to the invention can contribute, at least in part, to the enhancement of the oxidation state of the transition metal cations, affecting the crystal structure that has been stratified during cycling. Jahn-Tel
transition metals that reduce the distortion effect of ler and have a particularly high spin electronic structure (eg, N-electrons in the d-electronic state)
i ³⁺ ). Transition metal component, R-3m
Jahn-Teller, when doping any symmetrical material and making the divalent cations occupy the transition metal crystal lattice,
It is undoubted that it results in a reduction of the distortion and an enhancement of the electrochemical properties. Therefore, in its most usual sense, the present invention is directed to the development of materials with R-3m symmetry, in which the crystal lattice of a portion of the transition metal crystal layer is occupied by divalent positive ions, It is a substance containing a transition metal atomic layer.

The present invention is directed to the development of a negative electrode formed from the material developed in the present invention, a suitable positive electrode, and a cell containing an electrolytic solution compatible with the negative electrode and the positive electrode.

The materials of the present invention are characterized by high capacity, low capacity fading properties, and high voltage durability. The material clearly outperforms conventional lithium ion negative electrode materials, although of high capacity, but with high capacity of fading. As discussed below, the materials according to the present invention also show a greater improvement in both capacity and recyclability than the materials disclosed in the patent of US Pat. No. 5,591,543.

The present invention also relates to a process for producing a lithium-transition metal oxide material doped into a crystal. This process typically produces a homogeneous solid containing at least some amount of lithium-containing material, some amount of transition metal-containing material, and some amount of at least one Group II element. Contains substances. Next, the homogeneous solid is heat treated and one or more Periodic Table II
Produces active crystalline lithium transition metal oxidants that contain atoms of group III elements. After the amount of the substance containing lithium, the substance containing the transition metal, and the substance containing the element of Group II of the Periodic Table are selected, through the manufacturing process, the atoms of Group II of the Periodic Table in the active substance become Occupy the crystal lattice occupied primarily by the transition metal atoms in the crystalline layer of the active material. The method of producing a homogeneous solid is according to conventional and commonly known techniques. As the method, for example, stirring, gelling,
Spray drying, and solid synthesis. The process according to the invention still comprises the material developed according to the invention for forming the negative electrode of an electrochemical cell.

The material according to the invention comprises a lithium transition metal oxide having a rhombohedral R-3m symmetrical crystal structure in the undoped state, wherein the dopant of the divalent cation is mainly transition metal prior to being doped. Occupies the crystal lattice occupied by atoms. For example, as shown in FIG. 1, a lithium layer and a nickel atomic layer are alternately sandwiched between oxygen atoms in an R-3m structure in which LiNIO ₂ is layered. In its most usual sense, the present invention relates to materials in which at least a portion of the transition metal crystal lattice (eg, the nickel crystal lattice in the LiNiO ₂ structure of FIG. 1) is occupied by divalent positive ions. In the present invention, in order to obtain improved properties of the doped properties, a percentage, based on the total number of atoms, in the transition metal atomic layer of about 1 to 25, preferably about 3 to 15 substances. Must be added.

The details will be described below. The present invention is directed, in part, to compounds represented by the following molecular formulas: Li _{1 + x} Ni _{1- y My} N _x O _{2 (1 + x)} , and Li ₁ Ni _{1- y My} N _{x Op In} this, x, y and p are as described in the section for solving the above-mentioned problem. As a result of investigations by the present inventors, the electrochemical properties, in particular, the recyclability and the durability of the voltage, indicate that Li _{1 + x} Ni _1-y M
have a _y N _x O 2 molecular formula of _{(1 + x)} is the most suitable as a negative electrode material for lithium ion secondary batteries. Of the group of compounds, those of the following molecular formula have desirable properties; Li _{1 + x} NiN _x O _{2 (1 + x) wherein} N = Mg and 0.03 ≦ x ≦ 0.25, and more preferably 0.07 ≦ x ≦ 0.15
It is.

2. Li _{1 + x} Ni _1-y Co _y N _x O _{2 (1 + x)} , wherein N = Mg or Ca, 0.1 ≦ y ≦ 0.4,
And 0.03 ≦ x ≦ 0.25, and more preferably 0.3 ≦ x ≦ 0.15.

3. Li _{1 + x} CoN _x O _{2 (1 + x)} , where N = Mg or Ca, 0.03 ≦ x ≦ 0.2
5 and when N = Mg, more desirable
0.03 ≦ x ≦ 0.15.

The material according to the present invention can be formed on a negative electrode of a lithium ion secondary battery using a process for forming a lithium negative electrode structure with a conventional fine particle negative electrode active material. A cell according to the present invention includes one or more negative electrodes, one positive electrode, and an electrolyte compatible with the negative electrode and the positive electrode. Any suitable positive electrode material can be used in a secondary battery in combination with the material forming the negative electrode of the present invention. The components and structure of such positive electrodes should be familiar to those skilled in the art, but are not limited to, lithium metal; carbon, coke, graphite or other suitable carbon containing materials; aluminum or lithium. And amorphous silicon oxide; and transition metal oxides, sulfides, nitrogen compounds, oxynitrides, and oxygen carbides. The best cathode materials are coke and graphite. The cell containing the anode material according to the present invention may also be any suitable compatible liquid or solid electrolyte known in this regard, including, but not limited to, a solid state polymer electrolyte; State ceramic, glass or glass-ceramic electrolytes exhibiting high lithium ion conductivity and low electron conductivity, such as lithium borosilicate glass, lithium aluminum nitride, lithium borophosphosilicate
silicate); and one or more lithium salts (eg, lithium arsenic hexide).
afluoride), lithiumphosphorous
hexafluoride) and lithiumchlorate
e) one or more organic solvents such as ethyl carbonate, dimethyl carbonate
arbonate) and diethyl carbonate
Or a mixture thereof). The electrolyte used together with the cell having cork or graphite as the positive electrode is (i) 11.49% by weight of LiPF ₆ , 2
9.39% dimethyl carbonate by weight, and 59.11%
A mixture of ethylene carbonate by weight, and (ii)
For example, a solution of a solvent in which 1 mol of lithium phosphorus hexafluoride contains 45% by weight of ethyl carbonate and 55% by weight of dimethyl carbonate.

The secondary cell containing the negative electrode formed from the substance according to the present invention is assembled in various well-known structures in this area. These are configured as, but not limited to, flat, tubular, and spiral. The structure of the cell, including the positive electrode made of cork or graphite, uses polypropylene (pol
Use a separator made of ypropylene) or polyethylene. In the cell according to the present invention, the percentage of lithium in the active material of the negative electrode is sufficient to saturate the counter electrode during charging of the cell. The negative electrode and the positive electrode must have the ability to intercalate lithium ions on the other side through an electrolyte solution that is in contact with both electrodes. As a good example of a secondary cell structure according to the present invention, Li _1.1 Ni _0.75
Some include a negative electrode having a structure of Co _0.25 Mg _0.1 O _2.2 , a positive electrode of coke, an electrolyte based on LiPF ₆ and a separator made of polypropylene.

The method for producing a substance according to the present invention is an accurate chemical calculation method, in which a specified chemical substance is first provided, and these substances are appropriately combined to produce a uniform solid. Here, what is referred to as a "homogeneous solid" indicates that the separation of elements contained therein and required for chemical substances is minimized. This homogeneous solid is then heat treated under conditions that allow for the formation of the active substance. Here, the active substance refers to a substance capable of intercalating lithium ions into the structure or deintercalating lithium ions in each process of discharging and charging.
Inert substances do not have this property.

In addition, the substances according to the invention can be produced in any solid state, in a process based on the chemistry of single- or multi-form substances which can be produced in active form, having a composition within the scope of the invention. Alternatively, a wet solution (referred to as a solution that can be synthesized in a wet solution. Suitable methods of producing the substance of the present invention will be apparent to those skilled in battery technology. For example, sol-gel (sol-gel)
-gel) Solid-state synthesis and solution chemical synthesis methods such as synthesis, low-temperature chemical synthesis, and solution chemical processes. Technique 1
First, what is currently applicable is a known suitable synthesis method, which does not require undue experimentation, and also selects a suitable host material to produce a negative electrode material having a desired active form composition. According to the selected synthesis method, a parent substance is selected at room temperature and mixed in a solid state or a liquid solution. The substance produced by the synthetic method comprises, in single or multiple forms, an active substance having the crystalline composition of the invention,
Heat treatment is performed in an appropriate temperature range to obtain.

The four examples of the methods detailed below are suitable for producing the substances according to the invention. The examples below are not exhaustive, and there are countless other ways for those who are familiar with this area of technology. Therefore, these examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

A soluble chemical substance containing a required number of moles of an element has a required chemical quantity, and is dissolved in an appropriate solvent or synthetic solvent to form a uniform solution. Exemplary soluble compounds that can be used for each of the lithium, nickel, transition metals and Group II elements of the Periodic Table are listed in Table 2.

[0065]

[Table 2]

The identity of the appropriate solvent will depend on the identity of the soluble compound. For example, possible solvents include water, ethanol, methanol, ethylene glycol, or combinations thereof, for example, 80% by volume each.
Water / 20% ethanol and 95% methanol / 5% water. The solution is then dried at a temperature near or above the boiling point of the solvent or mixed solvent, with constant stirring. The drying method is selected from various known methods, for example, air drying or vacuum drying with stirring.

When evaporating one or more solvents, a uniform solid remains when the initial chemicals are homogeneously combined. Combining homog of the first chemical
eneously) is necessary to form a pure, single-form material. The solid obtained after evaporation is then heat treated under conditions suitable to provide the active substance of the present invention. Possible heat treatments include heating in air between about 600 ° C. and 850 ° C. for about 2-10 hours. The heated air is either statically or forcedly circulated, or fresh air is blown into the furnace. A further example of such a heating technique is to heat a substance at a temperature of 800 ° C. for 2 hours in a still air at a heating and cooling rate of 2 ° C./min. Other heating techniques should be familiar to those skilled in conventional battery manufacturing techniques.

Gelling method Lithium hydroxide or a suitable parent compound, containing one or more transition metals, is dissolved in a suitable organic solvent that will bind to the finished material. As the solvent, methyl alcohol is preferable. Chemicals containing the required Group II elements of the periodic table are dissolved in water while adjusting the pH value. If necessary, keep the chemical in solution. The other parent of lithium hydroxide is included in the solution, and its amount may be such that it can form the required molar amount and the active substance in chemical calculation. The possible identity of the parent compounds is the same as in the stirring method. The two solutions are mixed and left until gelling occurs. Thereafter, the gel is dried in a vacuum oven or in a rotary evaporator without vacuum to obtain a solid material. The solid is further processed in a manner related to the stirring method described above to produce the active form of the substance according to the invention.

Solid State Method Mechanical mixing of the required number of moles and chemical calculation of the appropriate host chemicals containing lithium, transition metals and Group II elements of the Periodic Table. In the solid-state synthesis method, suitable base chemicals include, but are not limited to, nitrate, hydroxide (hydroxide),
One of carbonate, acetate and formate,
Alternatively, it includes a combination thereof. Mechanical methods of making the mixture include rubbing and punching, grinding with a friction mill, ball milling.
ing) or use of other polishing machines or processes to create a homogeneous mixture. Such a mechanical process should be familiar to those skilled in this area of technology. The resulting mixture is subjected to a heat treatment to a single active or mixed form containing the required compounds. The usual method of heat treatment is at about 600 ° C. to 800 ° C. in stationary, circulating or flowing air for about 5 hours.
Heat the mixture for 20 hours. As an example of such a heat treatment, the mixture is heated at 750 ° C., 2 ° C./min and a cooling rate for 10 hours. Other heat treatment methods should be known to those skilled in the art. During the heat treatment, flash (f
It is also desirable to prevent the generation of dangerous gases by separating the charge in the furnace, either by flushing or replacing the atmosphere in the furnace.

Spray drying method The appropriate starting material is dissolved in a suitable solvent to provide a clear solution containing the required chemical calculations of lithium, the required transition metal and an element of Group II of the Periodic Table. Dissolve. The parent substances and solvents that can be used are the same as those used in the stirring method. The pH of the solution is adjusted by adding an appropriate amount of an organic or inorganic base or acid. Such bases and acids include, for example, nitric acid or hydrochloric acid. Solvents include, for example, one or more commonly known non-toxic solvents. The clear solution is sprayed into a chamber maintained at a temperature higher than the drying temperature of the solvent by turning the air into a spray gas with a spray nozzle. This involves either heating the room from the outside or passing heated air through the room to evaporate the solution and obtain a dry powder. The dried powder is separated from the evolving gas in a whirl separator. The collected solid is then suitably heat treated at a temperature above the decomposition temperature to become the active substance. This heat treatment procedure may be similar to that of the stirring method described above.

Electrochemical Properties Samples of the active substance according to the invention are prepared by several of the above procedures and tested for their electrochemical properties as negative electrode substances by the following procedure. Acetylene black (Super S, MMM Car)
bon, manufactured by Willecbroek. Belgium) and its copolymer binder (Scientific Polymer)
Products, Ontario, New York, 60% ethylene partially mixed ethylene-propylene copolymer) is mixed with trichloroethylene (trichloroethylene,
Aldrich, Light Music Chemistry Class). The mixture of active substance and acetylene black is added into the binder solution and stirred until it becomes muddy. The mud is spread on aluminum flakes and dried in air for 12 hours. The weight ratio of the active substance, acetylene black and binder in the last dried negative electrode is as follows. That is, 81.06% active, 7.6% acetylene black and 5.34% copolymer binder. A 1 cm ² area negative electrode disk is punched from the coated flakes and dried at a temperature of 130 ° C. for 12 hours under a pressure of less than 0.1 inch vacuum mercury. The dried negative electrode is used as a positive electrode of a lithium metal piece, a lithium metal reference electrode, and a separator (Whatman GF / D, Whatman Inc. Haverhi
1M in a mixture of ethylene carbonate and dimethyl carbonate (electrochemical grade, FMC Corp, Lithium Division) in a 2: 1 weight ratio.
Tested in a three-electrode cell consisting of an electrolyte containing LiPF ₆ . The assembled cell has a constant current density of 0.25 mA / in a voltage range of 3.1 V to 4.4 V.
Tested for 30 cycles in cm ² . The cell capacity at the end of each discharge cycle was also calculated.

[0072]

The following examples of materials according to the present invention have been formed into negative electrodes, assembled as cells, and tested for their electrochemical properties by the procedures described above. It should be understood that these examples are merely one representative of the vast scope of the present invention.

[0073] LiNi produced in Example 1 Gel _0.75 Co _0.25 Mg _0.03 O _p
(2.03 <p <2.06) Dissolve 0.1 mol of lithium hydroxide in 30 ml of water to make a clear and clear solution. Separately, 0.075 mol of nickel acetate (Aldrich, 98%) and 0.025 mol
150 m of Cobalt Acetate (Aldrich, 99%)
Dissolve in 1 liter of water to make a clear dark brown solution. Separately, 1 ml of 0.003 mol magnesium hydroxide
Was dissolved in water containing 70% nitric acid. Then, the lithium hydroxide solution and the magnesium hydroxide solution were added to a solution of cobalt and nickel acetate. This formed a cloudy, dark brown suspension. 90 ml of ethyl alcohol (200 pr)
oof) was added. It was believed that the addition of the alcohol facilitated the removal of acetate grooves from the acetate solution by the formation of ethyl acetate. Due to the low boiling point of ethyl acetate, it can be easily removed in the next drying step.

The suspended, dark pink solution is 500
It was dried at 120 ° C. under a millibar vacuum for 3 hours. The pressure was then reduced to 100 mbar at 140 ° C. for 1 hour to ensure complete drying. This drying procedure produced about 20 grams of a hard, tan, glassy solid. A 6 gram serving of this basic serving is 8 grams in air.
After heat treatment at 00 ° C. for 2 hours, about 2.8 grams of lithium nickel cobalt magnesium oxide was produced.

This powder was characterized by X-ray diffraction, secondary cells were formed, and the electrochemical properties were evaluated as described above. As shown in FIG. 2, the X-ray diffraction pattern is a substance exhibiting a monomorphic rhombohedral R-3m crystal structure.
It is. FIG. 3 shows a curve in which the specific capacity of a substance is plotted as a function of the number of cycles. FIG. 3 also shows lithium nickel cobalt oxide (LiNi _0.75 Co _0.25 O
The specific capacity of the compound without magnesium was plotted in ₂ ). The generation of this LiNi _0.75 Co _0.25 O ₂ is used a LiNi _0.75 Co _0.25 Mg _0.03 O _p same way as the generation of used in this example, does not contain hydroxide of magnesium (magnesium hydroxide).

FIG. 3 shows the fact that the magnesium-containing lithium nickel cobalt oxide material according to the invention has very good fading properties. Phasing of substances containing magnesium is 3
In the case of 0 cycle or more, only 0.1% / cycle was used.
Indicates 46% / cycle. The substances according to the invention are synthesized repeatedly in the above process and are similar to the other processes described in the examples below. And in each case,
The required fading property similar to that shown in the present embodiment is shown.

Example 2 LiNi _0.75 Co _0.25 N _0.3 O produced by the gel method
_p (2.03 <p <2.06, N = Ca, Ba or S
r) Calcium, barium and strontium doped lithium nickel cobalt oxide materials
0.1 mol of lithium hydroxide monohydrate, 0.075 mol of nickel acetate tetrahydrate, 0.025 mol of cobalt acetate tetrahydrate as starting substances, And 0.003
Synthesized according to the procedure of Example 1 above using molar calcium hydroxide, barium hydroxide or strontium hydroxide. The resulting gel was dried by rotary evaporation and heat treated at 800 ° C. in air for 2 hours. X-ray diffraction patterns obtained from the powder showed that the addition of calcium resulted in a single form of the substance, while the addition of strontium and barium had minimal impurities in the form of hydroxides. . The X-ray diffraction pattern received from the substance containing strontium and barium shows that the characteristic lattice parameter and the peak intensity ratio are dissolved in the lattice structure of the active substance of strontium and barium, as shown in FIG. It was convinced that it would improve cycling behavior. Calcium and strontium doped materials have only a slight decrease in capacity due to a decrease in volume.
At 3% / cycle, the capacity reduction of the barium doped material was 0.4% / cycle.

Example 3 LiNi _0.75 Co _0.25 Mg produced by spray drying
_0.03 O _p (2.03 ≦ p ≦ 2.06) 0.15 mol of nickel (II) acetate tetrahydrate (A
ldrich) and 0.05 moles of cobalt (II) acetate
The tetrahydrate was dissolved in 220 ml of methanol. Separately,
0.2 mol lithium hydroxide (Aldrich) was dissolved in 100 ml methanol. Separately, 0.006 mol of magnesium hydroxide was added to 400 ml with 2 ml of 70% nitric acid.
Dissolved in ml of water to get a clear solution. The lithium hydroxide solution was then added to the methanol solution containing the cobalt and nickel chemicals, and after stirring for 20 minutes, a precipitate formed upon re-dissolution. Prior to spray drying, an aqueous solution of magnesium hydroxide was added to the methanol solution containing the lithium, cobalt and nickel chemicals in the appropriate calculated amount. The resulting clear solution was spray-dried using equipment equipped with the following parameters.

[0079] Periataltic pump rate: 12-13 m
l / min. Atomized gas: 1.5 kgf / cm compressed air Temperature of heated drying air: 230 ° C. Aspirator speed: 70-10
0 L / min. Generated powder at 2 ° C./min to provide active
At a heating furnace temperature of 800 ° C. for 2 hours in stable air at a heating and cooling rate of. The advantages of the above process are:
A high specific surface area, narrow particle size distribution, and small crystal size that are convenient for synthesis.

The heated powder was characterized by X-ray diffraction and formed into a negative electrode material of a lithium ion secondary battery by the above procedure, and its electrochemical performance was evaluated.
5 and 6 show the X-ray diffraction pattern and the cycling action, respectively. The X-ray diffraction pattern of FIG. 5 exhibits a stratified R-3m structure, characteristic of a single form of material. FIG.
It includes a LiNi _0.75 Co _0.25 Mg _0.03 O _p material very good cycling stability according to the invention, to present facts only decrease the capacity of only 0.1% / cycle 30 cycles or more.

Example 4 LiNi _0.75 Co _0.25 Mg _0.03 synthesized by the solid-state method
O _p (2.03 ≦ p ≦ 2.06) lithium hydroxide monohydrate (chemical formula =
41.96, Aldrich) first with a punch and alumina slide
Polished for a minute to obtain a fine powder. Then 0.00
66 mol of magnesium hydroxide (chemical mass = 58.3)
3, Aldrich) to the lithium hydroxide powder and polish for an additional 5 minutes. After meticulously mixing and polishing lithium hydroxide monohydrate and magnesium hydroxide, 0.165 mol of nickel (II) hydroxide (chemical formula = 92.73, Al
drich) and 0.055 mol of cobalt (II) hydroxide (formula weight = 92.95, Aldrich), and 1 more
The mixture was polished for 5-20 minutes to produce a uniform powder. Acetone (30 ml) was added to this powder, mixed with a spatula to form a paste, and then placed in an aluminum crucible and heat-treated. This powder was heat-treated in air at 750 ° C. for 2 hours, and then a pattern obtained by X-ray diffraction was collected thereon.

A negative electrode of a lithium secondary battery was formed according to the procedure of the above example, and its performance was tested. FIGS. 7 and 8 show the X-ray diffraction pattern and cycling stability of the substance. The X-ray diffraction pattern of FIG. 7 shows a single form of physical properties having a crystal structure, which is substantially the same as the material prepared in Example 1. This substance is about 0.08%
/ Cycle showing very good cycling stability.

Example 5 Substance of the Present Invention with Different Magnesium Level Pure substance of the present invention, composition of formula (1), Li _1.03
Ni _0.75 Co _0.25 Mg _0.03 O _2.2 , Li _1.05 Ni _0.75 Co
_0.25 Mg _0.05 O _2.10 and Li _1.0 Ni _0.75 Co _0.25 M
The formation of the morphology with g _0.1 O _2.2 is due to the compounds LiOH, Ni (OH) ₂ , Co
It is completed using (OH) ₂ and Mg (OH) ₂ . These compounds are polished and mixed with a pestle and slide, and then mixed in a furnace.
It is formed by heating at 50 ° C. for 5 to 10 hours. In particular, the furnace (Lindberg Model 51524 box furnace) is 2 ℃ / mi.
n. It is heated to 750 ° C., kept at that temperature (750 ° C.) for 10 hours, and then cooled to room temperature at 2 ° C./min. When heating, use still air in the furnace. The powder is placed on an aluminum oxide (aluminum oxide) crucible in a furnace and heat treated.

The substances Mg _0.03 , Mg _0.05 and Mg _0.1
The patterns analyzed by X-rays of FIG.
Shown in (b) and FIG. 9 (c), showing the properties of the rhombohedral as a pure form within the R-3m sequence. The nature of the pure form of the substance is such that divalent magnesium cations occupy the transition metal crystal lattice rather than the lithium crystal lattice. This is because the crystal lattice number of lithium is equal to the sum of those of nickel, cobalt and magnesium.

The same process now described for the production of the pure form material described above involves the synthesis of three different magnesium-doped lithium-nickel-cobalt-oxide materials having the composition of the general formula (II) according to the invention. Used for The difference between the three compounds is only with respect to the content of magnesium. The nominal composition of these substances (nominalco
mposition) and the amount of different reactants used to produce each material are listed in Table 3 below.

[0086]

[Table 3]

The pattern presented by X-ray diffraction of each substance shown in Table 3 is the same as that of the substance produced in Example 1 in two characteristics of the single form substance. The specific capacities of these three materials over 30 discharge-recharge cycles are shown in FIG. The volume of the substance decreases with increasing magnesium content. However, cycling stability is maintained. FIG. 10 shows that capacity stability increases with increasing magnesium content,
With an increase in the magnesium content, the absolute value of the capacity decreases. When the magnesium ratio is 0.05 or 0.1, the fading of the capacity per cycle is 0.1.
% And the chemical calculated ratio of magnesium is 0.2, the fading of the capacity is 0.1% per cycle.
Only 04%.

Further Characterization of Materials According to the Invention US Pat. No. 5,591,543, issued to Peled et al, includes a group of lithium ion anode materials composed of Li _1-x Q _{x / 2} ZO _m. Was published. Z is cobalt,
A transition metal selected from nickel, magnesium, iron, vanadium and the like, Q is an element of Group II of the periodic table selected from calcium, magnesium, strontium and barium, and m is, due to the identity of Z,
Takes a value of 2 or 2.5. US Patent No. 5,591,
The inventor of the '543 patent states that a portion of the divalent cations in the Li _1-x Q _{x / 2} ZO ₂ material occupies the lithium crystal lattice within the crystal lattice, and that a portion of the divalent positive ions And in the form of a carbonate, interpreted as acting as a desiccant for the electrolyte during battery cycling.

The unique properties of the substance according to the invention are compared with those of the patent of US Pat. No. 5,591,543.
It becomes immediately apparent from the composition of the different atoms. Also, all or part of the Group II additives of the periodic table occupy the crystal lattice of the transition metal layer in the material according to the present invention. The proprietary additive occupies the crystal lattice of the lithium layer. The inventor has found that the substance has no significant fading,
It was shown that the battery can be charged up to 4.4V. The material of the U.S. Patent No. 5,591,543 can only cycle to 4.2V. This difference of 0.2 V is remarkable. For example, the difference of 0.2 V is 30 mA
A difference in specific capacity of h / g and a higher capacity and a higher voltage mean a higher practical material energy density. The result is remarkable even with a slight improvement of 10 mAh / g. In the case of a stratified compound,
The voltage versus charge curve is typically relatively flat at the high voltage end of the curve. And at least 30mAh
/ G is achieved by the present invention.

The substances according to the invention also have a substantially pure form. In contrast, US Pat.
The material according to the 1,543 patent contains impurities of metal oxides or carbonates of the Group II of the Periodic Table, and the cycling of the material, according to the inventor's explanation, is based on electrolytes due to the impurities. It is considered a likely result of the drying results. The inventors conclude that the presence of the oxide and carbonate forms is not necessary to achieve an improved recycle of the actives of the present invention. Instead, we believe that the structural stability of the active substance forms of the present invention is related to the electrochemical properties of the substance. We also compare the phasing of the volume and volume of the substance according to the invention with those of the patent of US Pat. No. 5,591,543, and show that the former has a much more significant improvement than the latter. State

In Examples 6 to 10 below, a comparison was made between the substance according to the present invention and the substance disclosed in the patent of US Pat. No. 5,591,543.

Example 6 Compound Li _1.05 Ni _0.75 Co _0.25 Mg _{0.05 according to the invention}
O _2.10 , Li _1.10 Ni _0.75 Co _0.25 Mg _0.1 O _2.2
After being synthesized using a solid state process, it was chemically analyzed (at Gal braith Labs Inc) to determine the moles of oxygen, nickel, cobalt and magnesium in the material. Before analysis, each compound was dried under vacuum at 150 ° C. for 3 hours. The results of the analysis are listed in Table 4 below. Table 4
Point out that the number of crystal lattices of oxygen in each compound is approximately equal to twice the sum of the crystal lattice numbers of nickel, cobalt and magnesium. In effect, Periodic Table II
Li _{1 + x} Ni _1-y MgN _x O _{2 (1 + x)}
It has been confirmed that the positive ions added to the substance occupy not the crystal lattice of lithium but the crystal lattice of the transition metal.

[0093]

[Table 4]

Example 7 Charge and Discharge Curves Substances according to the Invention Li _1.05 Ni _0.75 Co _0.25 Mg _0.05 O
FIG. 11 shows charge and discharge curves of _2.10 and Li _1.10 Ni _0.75 Co _0.225 Mg _0.1 O _2.2 . Current density 10μA / cm
This curve was obtained with a constant current of ² and a test cycle between 3.1 and 4.4V. Since the current value is small, the voltage measured by the electrometer should be close to the open circuit voltage as shown by the following equation. That is, V _detected = V _{open circuit} + IR I = current through the substance R = electrical resistance of the substance When I is very small, V _detected = V _{open circuit As} shown in Fig. 11, the same lithium content (shown on the X axis) However, as the amount of magnesium increases, the voltage level increases. This relationship is such that the measured voltage reflects (eg, 3.8 V when present in Ni ³⁺ LiNi, 4.5 when present in Ni ⁴⁺ NiO _2).
V) The oxidation state of the transition metal positive ion is increased by increasing the amount of the divalent positive ion added to the substance of the present invention. The oxidation state of the transition metal increases only when the divalent cation occupies the crystal lattice of the transition metal. Therefore, it can be further confirmed in FIG. 11 that the divalent positive ions in the substance Li _{1 + x} Ni _{1- y My} N _x O _{2 (1 + x)} of the present invention occupy the crystal lattice of the transition metal. That is.

Example 8 Content of divalent cations in the negative electrode before and after cycling The substance according to the invention Li _1.03 Ni _0.75 Co _0.25 Mg _0.03 O
The magnesium content in the negative electrode formed from _2.06 , Li _1.05 Ni _0.75 Co _0.25 Mg _0.05 O _2.10 , and Li _1.10 Ni _0.75 Co _0.25 Mg _0.10 O _2.20, was measured before and after cycling by energy dispersive spectroscopy.
(Specrtoscopy, EDX) to determine the magnesium content of the negative electrode before the test and cycling and the negative electrode tested (30 times of charging and discharging) in the other 30 cyclings. Table 5 shows the results of EDX. Almost no loss of magnesium content was observed in the doped anode after cycling. These results suggest that cycling does not cause loss of Group II elements. In contrast, the material of the patent of U.S. Pat. No. 5,591,543 is an alkaline earth carbonate in which elements of Group II of the periodic table dissolve during cycling.
There is a characteristic of an operation mode in which it disappears in the electrolyte in the form of oxide.

[0096]

[Table 5]

Example 9 Content of divalent cations in electrolyte before and after cycling In a secondary battery using the negative electrode materials listed in Table 5, before and after cycling, the electrolyte (L of 11.49% by weight) was used.
The magnesium content in iPF ₆ , 29.39% by weight dimethyl carbonate, and 59.11% by weight ethylene carbonate) is determined to the ppm level by chemical analysis. Table 6 shows the results. In the negative electrode itself, after cycling, almost no difference in the magnesium content in the electrolytic solution was observed. The same is true of the results of testing the electrodes after 30 cycles. With this result, the substance Li _{1 + x} Ni _{1- y My} N _x
The transition metal crystal lattice in O _{2 (1 + x)}
Occupied by magnesium and other divalent positive ions,
It was confirmed that it was not extracted from the negative electrode into the electrolyte.

[0098]

[Table 6]

As shown in Table 6, there is a slight increase in the magnesium content of the electrolyte after cycling, which is believed to be not due to the negative electrode material. Moreover, the presence of extra magnesium in the electrolyte during cycling does not appear to be related to the increased recyclability of the tested material. First, the original
The initial magnesium content cannot eliminate the fading properties of the material without the addition of divalent cations. Second, the increase in magnesium content due to the anode material from the beginning is substantially greater than the small increase measured by chemical analysis. For example, Li _1.0 Ni _0.75 Co _0.025 Mg
_In the case of _0.10 O _2.22 , the weight of the electrolytic solution used in the test cell was 1.0753 g, and the weight of the negative electrode was 0.0112 g. The weight of the active properties in the negative electrode was 4.7883 × 1
0 g, the weight of magnesium in the active substance is about 1.10
Should be 25 x 10 g. If all of the magnesium seeps into the electrolyte, the weight of magnesium measured will be about 102.53 ppm (1.1025 × 10
^-4 g ÷ 1.0753 g). The difference in weight of magnesium in the electrolyte before and after cycling was only 1.4 ppm, which was about 1% of the total magnesium content of the negative electrode material. Therefore, during cycling, there is no magnesium transfer from the negative electrode to the electrolyte.

We believe that the slight increase in measured magnesium is within the range of test errors. If the increase in magnesium in the electrolyte is not entirely due to test errors, the source of extra magnesium is probably the structural part of the assembled cell. It has been washed with a detergent containing one or more magnesium compounds for reuse.

As explained in the patent proposal of US Pat. No. 5,591,543, the inventors of the present invention have proposed that the dissolution of the compound of the Group II element in the periodic table during the charging in the electrolytic solution can be a problem. We believe in improving the cycling behavior of patented substances. The above results show that the change in magnesium content in the cell after repeated cycling according to the present invention is within the experimental error and not due to the dissociation of divalent cations from the negative electrode and dissolution in the electrolyte. I have. Therefore,
The enhancement of the capacity of the substance according to the invention is not due to the dissolution of the group ions, but rather due to the enhanced, structural stability of the substance according to the invention.

Example 10 TGA Analysis of Weight Loss The weight loss of the starting material in the heat treatment is used to determine the number of positions occupied by divalent positive ions in the crystal lattice of the substance of the present invention. For example, in the present invention, if magnesium ions occupy the crystal lattice of nickel or cobalt, the theoretical atomic crystal lattice ratio Li: Ni
Based on (or Co): O = 1: 1: 2, oxygen in chemical calculations is twice the sum of nickel, cobalt, magnesium, etc., and twice as much as lithium. On the other hand, if the positive ions of magnesium occupy the lithium crystal lattice, oxygen in chemical calculation is only the sum of nickel and cobalt, as in the patent of US Pat. No. 5,591,543. The reason is that US Pat. No. 5,591,543.
According to this patent, the amount of lithium must be replaced by divalent cations based on charge balance.
This is because two lithium ions are replaced by one divalent cation such as magnesium. As an illustrative case, Ni: Co: Mg = 0.75: 0.25:
Assuming 0.1, the chemical formula is Li _1.10 Ni _0.75 Co _0.25 Mg _0.1 O _2.2 when all magnesium cations are located in the crystal lattice of nickel (or cobalt).
Correspondingly, If all of the magnesium cations occupy lithium crystal lattice, based on the crystal lattice ratio charge balance, proper chemical formula Li _ag Ni _0.75 Co _0.25 M
g _0.1 O ₂ . Therefore, LiOH · H ₂ O, Ni
The solid state method as the starting compound of (OH) ₂ , Co (OH) ₂ and Mg (OH) ₂ should be valid for the proposed formula Li _1.10 Ni _0.25 Co _0.25 Mg _0.1 O ₂ of the present invention. . The solid state method also describes the compound and the compound Li _0.80 N of US Pat. No. 5,591,543.
Magnesium fraction of 0.1 of the divalent cation dopant of the latter compound, which should exhibit a structural difference between i _0.75 Co _0.25 Mg _0.1 O ₂ .

The occurrence of theoretical weight loss during the synthesis of the two compounds is calculated by the following method. Li _1.10 Ni
_To synthesize 1 mol of _0.75 Co _0.25 Mg _0.1 O _2.2 , theoretically, for example, 1.1 mol of LiOH.
H ₂ O, 0.75 mole of Ni (OH) _2, and requires 0.25 mole of Co (OH) ₂ and 0.1 mol of Mg (OH) _2. That is, 1.1LiOH.H ₂ O + 0.75Ni (OH) ₂ +
_{0.25Co (OH) 2 + 0.1Mg (} OH) 2 + heat treatment _{-Li 0.80 Ni 0.75 Co 0.25 Mg 0.1} O 2 reaction, at the start material 144.78g theoretically computationally 2
Estimating a weight loss of 8.16%, 104.015 g
There should be a product of

For Li _0.80 Ni _0.75 Co _0.25 Mg _0.1 O ₂ , a similar reaction occurs: 0.8 LiOH.H ₂ O + 0.75Ni (OH) ₂ +
_{0.25Co (OH) 2 + 0.1Mg (} OH) 2 + heat treatment _{-Li 0.80 Ni 0.75 Co 0.25 Mg 0.1} O 2 In this case, at the start material 132.188g theoretically 9
6.302 g of synthetic product are produced with a calculated weight loss of 2
7.15%.

The above two reactions were performed in a laboratory and FIG. 12 plots the weight loss of the run as measured by thermogravimetric analysis (TGA). Table 7 below summarizes all the weight changes that actually occurred between the starting compound and the final product.

[0106]

[Table 7]

The TGA results listed in Table 7 _confirm the accuracy of the chemical formula of the material Li _1.10 Ni _0.75 Co _0.25 Mg _0.1 O _{2.2 according} to the invention. The TGA analysis also shows that by measuring the different weight loss during the heat treatment, the Li _1.10 Ni
_0.75 Co _0.25 Mg _0.1 O _2.2 and U.S. Pat.
1,543 patent Li _0.80 Ni _0.75 Co _0.25 Mg _0.1
The structural differences between the _two O2 substances were sought without doubt. By checking the chemical formula of the substance, the difference in weight loss,
Alternatively, the position of the divalent positive ion of the substance can be confirmed. And, by TGA analysis, the position of the divalent cation also depends on the amount of lithium added as a starting material, so that the present invention and the US Pat. Structural differences were ensured.

Example 11 Comparison of Electrochemical Performance Materials examined in Example 5 Li _1.03 Ni _0.75 Co _0.25 Mg
_0.03 O _2.06 , Li _1.05 Ni _0.75 Co _0.25 Mg _0.05 O _2.10
And shows the _{Li 1.10 Ni 0.75 Co 0.25 Mg 0.1} O 2. 20 electrochemical on performance in the graph of FIG. 13. All three substances show very good recyclability and high capacity (150 mAh / g or more).

Example 12 Synthesis and Electrochemical Properties of Li _1.15 NiMg _0.15 O _2.3 As described above, the conventional solid state processing is based on the starting materials LiOH.H ₂ O, Ni (OH) ₂ and Mg (OH)
_From the chemical calculations of ₂ , it was used to synthesize the substance of the present invention. After being polished and mixed with a starting material, a pestle and a mortar, placed on an alumina crucible and placed in the air in a furnace for 8 hours.
Heat at 00 ° C. for 10 hours.

FIGS. 14 and 15 show the electrochemical properties of this material. FIG. 14 shows the function as a function of the number of volume cycles of the substance. According to this figure, the material does not fade in the first 30 cycles. This is not a normal phenomenon as undoped LiNiO ₂ (that is, LiNiO _{2 having} no Group II element in the periodic table). LiNiO ₂ added with Group II element of the periodic table and LiNi not added
O ₂ to explore differences between the two, showed dQ / dV of each substance in Figure 15 and 16 as a function of V (the potential of the cells). In FIG. 15, the substance Li _1.15 NiMg _0.15 O of the present invention is shown.
A dQ / dV vs. V curve of _2.3 is shown, indicating no change in morphology of the material during cycling, in contrast to the undoped material LiNiO ₂ shown in FIG. You will find that there is a significant difference between the two.

[0111] Example _{13 Li 1.10 Ni 0.75 Co 0.25 Mg} 0.10 materials electrochemical performance present invention _{O 2.2 Li 1.10 Ni 0.75 Co 0.25} Mg 0.10 O 2.2
The electrochemical cell containing the negative electrode and coke or the lithium positive electrode was constructed according to the above procedure. The test cell constructed in this manner was tested under several different experimental conditions described below.

In the first test, a test cell containing a coke positive electrode was charged at a current density of 0.50 V between 3.1 V and 4.4 V.
50 cycles were tested at mA / cm ² . FIG. 17 plots cell capacity as a function of cycle number. The figure shows the long life of an electrochemical cell containing the substance of the present invention.

In the second test, a test cell containing a lithium positive electrode was charged between 3.1 and 4.6 V at a current density of 0.5
50 cycles were tested at mA / cm ² . FIG. 18 plots cell capacity as a function of cycle number. The figure shows that cells containing the materials of the invention have the best voltage endurance when cycled at high voltages with little or no fading.

In the third test, a test cell containing a lithium positive electrode was set at 2.0 mA / c between 3.1 and 4.4 V.
was 100 cycle test in m ^2. FIG. 19 plots cell capacity as a function of cycle number. The drawing is
Cells containing the materials of the present invention show that they can maintain good recyclability even when cycled at ultra high current densities. The test cell can be fully charged or discharged in 15 to 20 minutes. It's roughly 4C C-
Equivalent to rate. Such high performance is generally not likely to be accompanied by high capacity and good recyclability at such abnormally high current densities. Therefore, the group of substances according to the invention comprises
Use lithium batteries to make them more applicable to automobiles.

In the above embodiment, the general chemical formula Li _{1 + x} Ni
_{1-y MgN x O 2 (} 1 + x) ( Formula I) was confirmed to be effective for a group of substances of the present invention. The above example still illustrates the theoretical conclusions of the inventors, namely,
The divalent cations in certain groups (Formula I) of the material occupy the crystal lattice in the transition metal of the material's crystal lattice and are described in US Pat. No. 5,591,543 in chemical formula, structure and electrochemical properties. It is also confirmed that the substance is different from that of the patent of the US patent.

Chemical formula Li₁Ni_1-yMgN_xO_p(Formula I
A second group of substances of the invention having I) is also the US
Patent Li, Patent No. 5,591,543_1-yQ
_{x / 2}ZO _mAlso different from (Formula III). Represented by three chemical formulas
The chemical composition used is also different. In formula I, the lithium atom
Are nickel, “M” transition metal and “N” periodic table
The sum of the group II atoms is equal. In the formula, the lithium source
The number of atoms is equal to the sum of the number of atoms of nickel and "M" transition metal.
Equally, the number of atoms in Group II of the "N" Periodic Table is an independent parameter.
Data. In Formula III, the number of lithium atoms is
Any time a "Z" transition metal atom (Z is nickel,
G, manganese or a combination of two or more
C) less than the number, the number of A atoms in group II of the "Q" periodic table is
Depends on the number of lithium atoms.

With respect to the electrochemical properties of the above substances, substances of the formula I usually perform best, followed by substances of the formula II. For example, as shown in FIG.
(The composition Li represented by-○-and-□-, respectively)
_1.10 Ni _0.75 Co _0.25 Mg _0.10 O _2.2 and Li ₁ Ni _0.75
Co _0.25 Mg _0.10 O _p having a (2.1 ≦ p ≦ 2.2)) is in the United States Patent Patent No. 5,591,543, of the formula III material (composition Li _0.8 Ni _0.75 Co _0.25 Mg
₍ Having _0.10 O _2.0 ), a remarkable improvement in its specific capacity is observed.

The positions occupied by divalent cations in the substances of the formulas I, II and III are also different. For example, in Formula I, the number of oxygen crystal lattices is twice the number of lithium crystal lattices, and nickel + “M” transition metal + “N” periodic table
It is twice the sum of the crystal lattices of Group II elements. In Formula III, the number of oxygen crystal lattices is twice the sum of the crystal lattices of nickel + "M" transition metal. In formula III, the lithium crystal lattice is (1-x) lithium + X / 2 “N” crystal lattice of group II atom of the periodic table + X / 2 empty lattice.
ce). In Formula II, the number of oxygen crystal lattices is not exactly estimated from the nominal formula. The number of oxygen crystal lattices is presumed to be such that if the X / 2 "N" group II positive ion of the periodic table is a lithium crystal lattice,
If the positive ions of group II of the periodic table of X / 2 occupy the transition metal crystal lattice respectively, the number of oxygen crystal lattices is 2 (1+ (X / 2)), or if the number of oxygen crystal lattices is Would occupy the transition metal crystal lattice and leave a lithium vacancy of X, which would be 2 (1 + X). In any case, at least X / 2 of the "N" Group II positive ions of the periodic table occupy the crystal lattice of the transition metal layer in the material of Formula II. And, at present, the search suggests that the cycling properties of the material of formula II are the result of the positive ions of group II of the periodic table being placed on the transition metal crystal lattice.

[0119] Therefore, the substance to be limited by the Formula I and II of the present invention is believed to be included in the material of a single group of through type _{Li 1 + x Ni 1-y} M y N x O p.

In the formula, M is titanium, vanadium, chromium,
Selected from manganese, iron, cobalt and aluminum;
N is selected from magnesium, calcium, strontium, barium and zinc; 0 ≦ X ≦ Z; 2 (1 + Z /
2) ≦ P ≦ 2 (1 + Z); when M is cobalt or manganese, 0 ≦ y ≦ 1; when M is titanium, vanadium, chromium or iron, 0 ≦ y ≦ 0.5; when M is aluminum, y ≦ 0.4; 0 ≦ Z ≦ 0.25 when N is aluminum or calcium; 0 <Z ≦ 0.1 when N is strontium, zinc or barium; The comparative examples with those of the '591 543 patent should not be considered in any way, and it is believed that there are still many significant differences between the various materials.

[0121]

Thus, the present inventors have found that an appropriate amount of a restricted Group II element of the Periodic Table has been added to a transition metal crystal lattice in a lithiated transition metal oxide exhibiting an R-3m structure. We have obtained a new material with improved cycling behavior and other beneficial electrochemical properties. The above examples of substances according to the invention have in principle magnesium as the dopant of the divalent cation and nickel and cobalt as the transition metals. In any case, by adding appropriate amounts of lithium and transition metal in chemical calculation, this divalent cation becomes R-3m
Occupying the transition metal crystal lattice within, the scope of the present invention also includes:
The addition of these divalent cations was considered. magnesium,
The interchangeable nature of calcium, strontium and barium is particularly clear. The addition of them to the substance according to the invention has substantially the same advantageous effect. Transition metal,
In principle, titanium, vanadium, chromium, manganese,
Iron, cobalt and aluminum can also be inferred for their compatibility. Such evidence of compatibility is, for example, the compound of US Pat. No. 5,264,201.

[0122] Regarding the present invention, many modifications may be made if those skilled in the art are familiar with the present invention, but they do not depart from the scope and spirit of the present invention. Therefore,
The appended claims are not limited to the specific embodiments and other descriptions described above, but rather the claims should cover all patentable features of the invention.
To that end, the features obtained from the above changes should be considered equivalent.

[Brief description of the drawings]

The features and advantages of the present invention will be more readily understood by reading the above embodiments with reference to the following drawings.

FIG. 1 is a structural diagram of a lithium nickel oxide (LiNiO ₂ ) layer having a rhombohedral structure.

Fig. 2 Powdered compound LiNi produced by gel method
_{0.75 Co 0.25 Mg 0.03 O p (} 2.03 ≦ p ≦ 2.06)
FIG. 3 is a pattern diagram diffracted by X-rays.

FIG. 3 LiNi _0.75 Co _0.25 M synthesized by gel method
g _0.03 O _p (− ○ −

[Outside 1] FIG. 4 is a curve diagram in which is plotted as a specific capacity versus the number of cycles.

FIG. 4 LiNi _0.75 Co _0.25 N synthesized by gel method
_0.03 O _p flop a (2.03 <p <2.06) in specific capacity versus cycle number for electrochemical cell comprising a negative electrode material

[Outside 2] ○-) or barium (-□-).

FIG. 5 is a powdery compound L synthesized by spray drying.
_{iNi 0.75 Co 0.25 Mg 0.03 O p} (2.03 <p <2.
FIG. 06 is a pattern diagram diffracted by X-rays.

FIG. 6 LiNi _0.75 C synthesized by spray drying
o _0.25 Mg _0.03 O _p a (2.03 ≦ p ≦ 2.06) is a curve diagram obtained by plotting the electrochemical cell at specific capacity versus cycle number containing as an anode material.

[7] the powdered compound was synthesized in a solid state process _{LiNi 0.75 Co 0.25 Mg 0.03 O p} (2.03 ≦ p ≦
2.06) is a pattern diagram diffracted by X-rays.

FIG. 8: LiNi _0.75 synthesized by solid state process
It is a curve diagram obtained by plotting the ratio capacity versus cycle number Co _0.25 Mg _0.03 O _p electrochemical cell comprising a (2.03 ≦ p ≦ 2.06).

FIGS. 9 (a)-(c) show three oxides, Li _1.03 Ni _0.75 Co, synthesized in a solid state process.
_0.25 Mg _0.03 O _2.06 , Li _1.05 Ni _0.75 Co _0.25 Mg
_0.05 O _2.10 and Li _1.10 Ni _0.75 Co _0.25 Mg _0.1 O
Figure 2 is a pattern diagram diffracted by X-rays showing the pure form properties of _2.2 .

FIG. 10 shows Li synthesized in a solid-state process.
Ni _0.75 Co _0.25 M

[Outside 3] _{0.75 Co 0.25 Mg 0.20 O p (} - × -) which is a curve diagram obtained by plotting the ratio capacity versus cycle number of an electrochemical cell comprising a negative electrode material.

FIG. 11: Open circuit voltage vs. material Li _1.05 Ni _0.75 Co _0.25 Mg _0.05 O _2.10 and Li _1.10 N during charge / discharge cycles
FIG. 4 is a curve diagram plotted with lithium content in i _0.75 Co _0.25 Mg _0.10 O _2.2 .

FIG. 12. Weight loss obtained by TGA versus Li _1.10 Ni _0.75 Co _0.25 Mg _0.1 O _2.2 recorded during heat treatment (solid line).
FIG. 3 is a curve diagram plotting the temperatures of Li _0.8 Ni _0.75 Co _0.25 Mg _0.1 O ₂ (dotted line).

FIG. 13: Li _1.03 Ni _0.75 Co _0.25 Mg
_0.03 O _2.06 , Li _1.05 Ni _0.75 Co _0.25 Mg _0.05 O _2.10
FIG. 4 is a curve diagram plotting specific capacity versus cycle number of an electrochemical cell containing Li _1.10 Ni _0.75 Co _0.25 Mg _0.1 O _2.2 as a negative electrode material.

FIG. 14 is a curve diagram plotting the capacity of the substance Li _1.15 NiMg _0.15 O _2.3 versus the number of cycles.

FIG. 15: dQ / of the substance Li _1.15 NiMg _0.15 O _2.3
FIG. 4 is a curve diagram plotted with dV versus cell potential (V).

FIG. 16 is a curve plotted with dQ / dV of the conventional substance LiNiO ₂ versus cell potential (V).

FIG. 17: Li _1.10 Ni _0.75 Co _0.25 Mg _0.10 O _2.2
FIG. 4 is a curve diagram plotting the specific capacity versus the number of cycles of an electrochemical cell using as a negative electrode and coke as a positive electrode. ²

FIG. 18: Li _1.10 Ni _0.75 Co _0.25 Mg _0.10 O _2.2
FIG. 4 is a curve diagram in which an electrochemical cell having lithium as a positive electrode is plotted in terms of capacity versus cycle number, and a cycle voltage range is from 3.1 to 4.6 V, 30 cycles,
The current density is 0.50 mA / cm ² .

FIG. 19: Li _1.10 Ni _0.75 Co _0.25 Mg _0.10 O _2.2
FIG. 4 is a curve diagram in which an electrochemical cell using lithium as a positive electrode and lithium as a positive electrode is plotted in terms of capacity vs. cycle number. ²

FIG. 20 Anode material Li _1.10 Ni _0.75 Co _0.25 Mg
_0.10 O _2.2 , Li ₁ Ni _0.75 Co _0.25 Mg _0.10 O
_p (2.1 ≦ p ≦ 2.2), and Li _0.8 Ni _0.75 C
FIG. 4 is a curve diagram plotting an electrochemical cell containing o _0.25 Mg _0.1 O _2.0 in terms of specific capacity versus cycle number.

 ────────────────────────────────────────────────── ─── Continuation of the front page (71) Applicant 598055828 5000 Forbes Avenue, Pittsburgh, Pennsylvania 15213, U.S.A. S. A. (72) Inventor Mandeam A. Suriram United States, Pennsylvania 15224, Pittsburgh, S.E. Atlantec # 2,365 (72) Inventor Chun-Chi Chang 5213 Bayard Road, Pittsburgh, 15213, Pennsylvania, United States. 106

Claims (29)

[Claims] 1. The method of claim 1, comprising lithium, oxygen and at least one transition metal, further comprising a crystalline material.
crystalline material characterized in that it contains divalent cations in the atomic layer of the ial), which mainly occupy the crystal lattice to be occupied by the transition metal atoms. 2. The crystalline material according to claim 1, wherein the crystalline material has a single-form R-3m crystal structure when the divalent cation is not present. 3. The crystalline material according to claim 2, wherein a part of the lithium can be reversibly removed from the crystal structure. 4. The crystalline substance according to claim 3, wherein the divalent cation in the transition metal layer promotes an oxidation state of the transition metal ion in the substance. 5. The ratio of the presence of the divalent positive ion is as follows:
The crystalline material according to claim 3, characterized in that it is 1 to 25% based on the total number of atoms in the crystal layer of the material mainly occupied by transition metal atoms. 6. The crystalline material according to claim 5, wherein the ratio is an atomic ratio of 3 to 15%. 7. The method according to claim 1, wherein the divalent positive ion is one or one.
4. The crystalline material according to claim 3, wherein the crystalline material is an ion of one or more Group II elements of the periodic table. 8. The crystalline substance according to claim 7, wherein the group II elements of the periodic table are an alkaline earth metal element and zinc. 9. The crystalline material according to claim 8, wherein the alkaline earth metal element is magnesium, calcium, strontium and barium. 10. The crystal according to claim 3, wherein said transition metal is selected from one or more of titanium, vanadium, chromium, manganese, iron, cobalt and aluminum. Substance. 11. has a composition _{Li 1 + x Ni 1-y} M y N z O p, in the composition, M is selected from titanium, vanadium, chromium, manganese, iron, cobalt and aluminum; N magnesium , Calcium, strontium, barium and zinc; 0 ≦ x ≦ z; 2 (1 + z / 2) ≦ p ≦ 2 (1 + z);
When M is titanium, vanadium, chromium or iron,
0 ≦ y ≦ 0.25; when M is aluminum, y ≦
0.4; when N is magnesium or calcium, 0 ≦ z ≦ 0.25; when N is strontium, zinc or barium, 0 ≦ z ≦ 0.1; 2. The crystalline substance according to 1. 12. Composition Li _{1 + x} Ni _{1- y My} N _x O
Having _{2 (1 + x)} , wherein M is selected from titanium, vanadium, chromium, manganese, iron, cobalt and aluminum; N is selected from magnesium, calcium, strontium, barium and zinc; 0 ≦ y ≦ 1 when M is cobalt or manganese; 0 ≦ y ≦ 0.5 when M is titanium, vanadium, chromium or iron; y ≦ 0.4 when M is aluminum; 0 ≦ x ≦ 0.25 when N is magnesium or calcium; 0 ≦ x ≦ 0.2 when N is strontium, barium or zinc.
12. The crystalline substance according to claim 11, wherein 13. The composition Li ₁ Ni _1-y M has a _y N _x O _p, in the composition, M is selected from titanium, vanadium, chromium, manganese, iron, cobalt and aluminum; N is magnesium, Selected from calcium, strontium, barium and zinc; when M is cobalt or manganese,
0 ≦ y ≦ 1; when M is titanium, vanadium, chromium or iron, 0 ≦ y ≦ 0.5; when M is aluminum, y ≦ 0.4; and when N is magnesium or calcium, 0 ≦ x ≦ 0.25; when N is strontium, barium or zinc, 0 ≦ x ≦ 0.1;
13. The crystalline material according to claim 12, wherein 2 (1 + x / 2) ≦ p ≦ 2 (1 + x); 14. A negative electrode of an electrochemical cell, which is a negative electrode containing the substance according to claim 1. 15. The negative electrode according to claim 14, comprising the substance according to claim 11. 16. The negative electrode according to claim 15, comprising the substance according to claim 12. 17. The negative electrode according to claim 15, comprising the substance according to claim 13. 18. A lithium ion secondary cell, comprising: a negative electrode having the configuration according to claim 14; a positive electrode compatible with the negative electrode; and an electrolyte solution compatible with the positive electrode. 19. The lithium ion secondary cell according to claim 18, comprising the negative electrode having the configuration according to claim 15. 20. The lithium ion secondary cell according to claim 18, comprising the negative electrode having the configuration according to claim 16. 21. The lithium ion secondary cell according to claim 18, comprising the negative electrode having the configuration according to claim 17. 22. In the manufacturing process, a. Procedure for combining a substance containing at least an amount of lithium, a substance containing an amount of a transition metal, and a substance containing an amount of an atom of at least one Group II element of the Periodic Table, thereby producing a homogeneous solid And b. Heat treating said homogeneous solid to produce an active crystalline lithium transition metal oxide material comprising atoms of said at least one Group II element of said periodic table, wherein said at least one Group II element of said Periodic Table in said active material; A lithium transition comprising the steps of selecting the amount so that the atoms of the element occupy the crystal lattice that was mainly occupied by the transition metal atoms in the crystal layer of the active material. Manufacturing process of metal oxide crystalline material. 23. The method of claim 2, wherein the steps of combining include: a. Dissolving said amount in at least one solvent to provide a homogeneous solution; b. Drying the homogenous solution to provide the homogenous solid while constant stirring removes the solvent from the homogenous solution. 24. The method of claim 1, wherein the combining comprises: a. Dissolving said amount in at least one solvent to provide a homogeneous solution; b. Spraying the uniform solution into a room through a spray nozzle, maintaining the room temperature at or above the drying temperature of the solvent and evaporating the solvent to provide the uniform solid in powder form. 23. The method according to claim 22, wherein
The process described in. 25. The method as claimed in claim 25, wherein the lithium-containing substance is lithium hydroxide.
ide), wherein the step of coupling comprises: a. Dissolving said amount of lithium hydroxide and said amount of material comprising a transition metal in one organic solvent to produce a solution containing lithium; b. Preparing an aqueous solution of the substance containing the Group II element of the periodic table; c. Mixing the aqueous solution and the lithium-containing solution together; d. Leaving the mixture to provide a gel until gelation occurs; e. 23. The process of claim 22, comprising drying the gel to obtain the uniform solid. 26. The process according to claim 22, wherein said active crystalline lithium transition metal oxide material comprising an atom of said at least one Group II element of the periodic table has a composition according to claim 11. . 27. The process according to claim 26, wherein the active crystalline lithium transition metal oxide comprising the at least one group II element of the periodic table has a composition according to claim 12. . 28. The process according to claim 26, wherein the active crystalline lithium transition metal oxide material comprising an atom of the at least one Group II element of the Periodic Table has a composition according to claim 13. . 29. The method according to claim 1, wherein
A process for producing a lithium ion secondary cell, comprising forming a cell from a negative electrode having the composition described in 4, a positive electrode compatible with the negative electrode, and an electrolytic solution compatible with the negative electrode.