JP2015182922A - Nickel-manganese compound oxide having cubic spinel structure and method for producing the same, and use thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nickel-manganese compound oxide having a cubic spinel structure, a lithium-nickel-manganese compound oxide which is obtained by using the nickel-manganese compound oxide having a cubic spinel structure, and a lithium secondary battery using the lithium-nickel-manganese compound oxide as a cathode.SOLUTION: The nickel-manganese compound oxide having a cubic spinel structure is provided which has: a chemical composition formula represented by (NiM1MnM2)O(where, M1 and M2 each represent one selected from among Mg, Al, Ti, V, Cr, Fe, Co, Cu, Zn, and Zr; and 0≤x≤0.1, 0≤y≤0.25, and 0≤α≤0.05) ; crystal structure of a cubic spinel structure; and a crystallite diameter of 80 to 500Å. The method for producing the nickel-manganese compound oxide and the use thereof are also provided.

Description

  The present invention relates to a nickel-manganese composite oxide, a method for producing the same, and its use. Specifically, the nickel-manganese composite oxide suitable as a precursor of a lithium-nickel-manganese composite oxide, The present invention relates to a lithium-nickel-manganese composite oxide obtained using the nickel-manganese composite oxide and a lithium secondary battery using the lithium-nickel-manganese composite oxide as a positive electrode.

  A spinel-type lithium-nickel-manganese composite oxide has attracted attention as a positive electrode active material for 5V class lithium secondary batteries. The lithium-nickel-manganese composite oxide has a superlattice structure in which nickel and manganese are regularly arranged. The production method of this substance includes a solid phase reaction method in which a nickel source and a manganese source are mixed and calcined, and a composite carbonate, composite hydroxide, composite oxyhydroxide, composite oxide containing nickel and manganese as a precursor. There is a manufacturing method. The composite compound containing nickel and manganese is a preferable precursor when the ordered arrangement of nickel and manganese is premised because the metal is more uniformly distributed.

  For example, it is disclosed that a nickel-manganese composite oxide obtained by firing a nickel-manganese composite compound obtained by a coprecipitation method is used as a precursor of a lithium-nickel-manganese composite oxide (Patent Document 1). .

  Further, it is disclosed that a nickel-manganese composite oxide obtained by spray-drying and firing a nickel salt and a manganese salt is used as a precursor of a lithium-nickel-manganese composite oxide (Patent Document 2).

When the crystal lattice of the precursor of these lithium-nickel-manganese composite oxides is cubic and other crystal structures are the main components, it is difficult for the positive electrode active material to have a desired crystal structure. Is disclosed (Patent Documents 1 and 2).
In the method for producing a cubic spinel-based manganese nickel composite oxide using a manganese nickel composite oxide as a raw material by liquid phase synthesis with Mn ₃ O ₄ as a core in Patent Document 1, it is necessary to fire in a temperature range of 900 to 1000 ° C. There is.

  Moreover, also in the manufacturing method of the cubic spinel type manganese nickel complex oxide by the solid-phase method using the spray dryer of patent document 2, 3, the baking in the temperature range of 800-1000 degreeC is required.

  Thus, in order to obtain a cubic spinel type nickel manganese composite oxide, firing at a high temperature of 800 ° C. or higher is required.

  For this reason, there exists a subject that a simple manufacturing method is required at lower cost.

JP 2012-216547 A JP 2004-303710 A JP 2006-196293 A

  An object of the present invention is to provide a cubic spinel type nickel manganese composite oxide obtained by firing at a low temperature in a method for producing a cubic spinel type manganese nickel composite oxide. Another object of the present invention is to provide a lithium secondary battery using a lithium-nickel-manganese composite oxide obtained by using as a positive electrode.

The present inventors diligently studied a precursor of a lithium-nickel-manganese composite oxide. As a result, it has been found that a cubic spinel oxide is produced at a low firing temperature by heat-treating a tetragonal spinel structure nickel-manganese composite oxide. It has been found that a lithium secondary battery using a lithium-nickel-manganese composite oxide having a composite spinel oxide as a precursor as a positive electrode has high performance, and has completed the present invention. That is, according to the present invention, the chemical composition formula is (Ni _{(0.25 ± α) −x} M1 _x Mn _{(0.75 ± α) −y} M2 _y ) ₃ O ₄ (where M1 and M2 are Mg, Al, respectively) Represents one selected from Ti, V, Cr, Fe, Co, Cu, Zn and Zr, 0 ≦ x ≦ 0.1, 0 ≦ y ≦ 0.25, and 0 ≦ α ≦ 0.05 A cubic spinel structure nickel-manganese based composite oxide, characterized in that the crystal structure is a cubic spinel structure and the crystallite diameter is 80 to 500 mm, and its production method, and It is a use.

  Hereinafter, the present invention will be described in detail.

The cubic spinel structure nickel-manganese composite oxide of the present invention has a chemical composition formula of (Ni _{(0.25 ± α) -x} M1 _x Mn _{(0.75 ± α) -y} M2 _y ) ₃ O _4. (However, M1 and M2 each represent one selected from Mg, Al, Ti, V, Cr, Fe, Co, Cu, Zn and Zr, and 0 ≦ x ≦ 0.1, 0 ≦ y ≦ 0.25. And 0 ≦ α ≦ 0.05. Ni + M1 = 0.25 ± 0.05 and Mn + M2 = 0.75 ± 0.05. When these values are deviated, they deviate from the formal valences of Ni ²⁺ and Mn ^{4+ and} are around 5V (based on Li metal negative electrode). Battery capacity decreases. Ni: Mn = 0.25: 0.75 is preferable. Different element substitution (M1, M2) can be expected to improve battery performance, in particular, charge / discharge cycle stability and suppress Mn elution. In order to maintain the degree of order of the Ni—Mn ordered arrangement in the spinel type sublattice and the battery capacity in the 5 V region, it is preferable that the amount of substitution of different elements for Ni is small. Specific examples of the chemical composition include (Ni _0.25 Mn _0.75 ) ₃ O ₄ , (Ni _0.25 Mn _0.65 Ti _0.10 ) ₃ O ₄ , (Ni _0.20 Fe _{0. 05 Mn 0.75) 3 O 4,} (Ni 0.23 Mg 0.02 Mn 0.75) 3 O 4, include _{(Ni 0.23 Zn 0.02 Mn 0.75)} 3 O 4 and the like.

  The cubic spinel structure nickel-manganese composite oxide of the present invention has a cubic spinel type crystal structure. The cubic spinel type is advantageous in that the elemental distribution of Ni and Mn is made uniform and a Ni—Mn ordered arrangement is easily realized. In addition, since both the raw material and the final product, the lithium-nickel-manganese composite oxide, have a spinel structure, the reaction between the raw material and the lithium compound may proceed smoothly. Here, the cubic spinel type means that the crystal lattice is classified as cubic, the crystal structure is a spinel type, and the space group is Fd-3m.

  The cubic spinel structure nickel-manganese composite oxide of the present invention has a crystallite diameter of 80 to 500 mm. When the crystallite diameter is less than 80 mm, the crystallites of the raw material are aggregated during the synthesis of the lithium-nickel-manganese composite oxide, and the metal element distribution is not uniform. When the crystallite diameter exceeds 500 mm, the reactivity between the raw material and the lithium source decreases, and the metal element distribution of the lithium-nickel-manganese composite oxide as the final product is not uniform.

The tap density of the cubic spinel structure nickel-manganese composite oxide of the present invention is preferably 1.0 g / cm ³ or more because the filling density of the positive electrode active material in the electrode affects the energy density. More preferably, it is 1.5 g / cm ³ or more, and particularly preferably 2.0 g / cm ³ or more. When the tap density is 1.0 g / cm ³ or more, the filling property of the lithium-nickel-manganese composite oxide obtained using the cubic spinel structure nickel-manganese composite oxide of the present invention as a raw material tends to be high. .

  Since the theoretical average valence of the cubic spinel structure nickel-manganese composite oxide of the present invention is 2.7, the average valence of Ni, Mn, M1, and M2 in the chemical composition formula is 2.5 to 2.5. 2.9 is preferable, and 2.6 to 2.7 is more preferable. Here, the average valence is determined by an iodometry method.

  The average particle size of the cubic spinel structure nickel-manganese composite oxide of the present invention is preferably 5 to 20 μm and more preferably 5 to 10 μm in order to adapt to the particle size at which an electrode can be easily formed. The average particle diameter is an average particle diameter of secondary particles in which primary particles are aggregated, that is, a so-called aggregated particle diameter.

Cubic spinel structure nickel present invention - the specific surface area of the manganese-based composite oxide, in order to ensure the filling property, preferably at 50 m 2 / ^g or less, more preferably 10 m 2 / ^g or less. In general, since the filling property and the specific surface area have a correlation, a powder having a high filling property is easily obtained with a low specific surface area.

  The particle distribution of the cubic spinel structure nickel-manganese composite oxide of the present invention is a particle size distribution having a monodisperse, that is, a monomodal distribution.

  Next, a method for producing the cubic spinel structure nickel-manganese composite oxide of the present invention will be described.

The cubic spinel structure nickel-manganese composite oxide of the present invention has a chemical composition formula of (Ni _{(0.25 ± α) -x} M1 _x Mn _{(0.75 ± α) -y} M2 _y ) ₃ O _4. (However, M1 and M2 each represent one selected from Mg, Al, Ti, V, Cr, Fe, Co, Cu, Zn and Zr, and 0 ≦ x ≦ 0.1, 0 ≦ y ≦ 0.25. And 0 ≦ α ≦ 0.05), the space group is I41 / amd, the lattice constant a is 5.7 to 5.9Å, and the lattice constant c is 8.8 to 9.4Å. A certain tetragonal spinel-type nickel-manganese composite oxide can be used as a raw material and fired at 250 ° C. or higher. When the firing temperature is less than 250 ° C., a mixed phase with a tetragonal spinel oxide is formed. In order to keep the shape of the product and prevent sintering, it is preferably fired at 250 to 900 ° C, more preferably 250 to 600 ° C, and particularly preferably 250 to 500 ° C.

  The production of the cubic spinel structure nickel-manganese composite oxide of the present invention does not require control of the atmosphere, and can be performed in a normal air atmosphere.

  The cubic spinel structure nickel-manganese composite oxide of the present invention has high dispersibility of metal elements, and can be used for the production of lithium-nickel-manganese composite oxide.

  In the case of producing a lithium-nickel-manganese composite oxide using the cubic spinel structure nickel-manganese composite oxide of the present invention as a raw material, the production method comprises the steps of: nickel-manganese composite oxide and lithium compound. It is preferable to have a mixing step of mixing and a firing step.

  In the mixing step, any lithium compound can be used. Examples of the lithium compound include one or more selected from the group consisting of lithium hydroxide, lithium oxide, lithium carbonate, lithium iodide, lithium nitrate, lithium oxalate, and alkyl lithium. As a preferable lithium compound, any one or more selected from the group of lithium hydroxide, lithium oxide and lithium carbonate can be exemplified.

  In the firing step, the raw materials are mixed and then fired to produce a lithium-nickel-manganese composite oxide. Firing can be performed at any temperature of 500 to 1000 ° C. in various atmospheres such as air and oxygen.

  The lithium-nickel-manganese composite oxide thus obtained is used as a positive electrode active material for a lithium secondary battery.

  As the negative electrode active material used in the lithium secondary battery of the present invention, metallic lithium and a material capable of occluding and releasing lithium or lithium ions can be used. Examples include lithium metal, lithium / aluminum alloy, lithium / tin alloy, lithium / lead alloy, and carbon materials that can electrochemically insert and desorb lithium ions. A carbon material that can be desorbed is particularly preferable in terms of safety and battery characteristics.

  Further, the electrolyte used in the lithium secondary battery of the present invention is not particularly limited. For example, a lithium salt dissolved in an organic solvent such as carbonates, sulfolanes, lactones, ether condyles, or lithium ion conductivity. The solid electrolyte can be used.

  Moreover, there is no restriction | limiting in particular as a separator used with the lithium secondary battery of this invention, For example, the microporous film made from polyethylene, a polypropylene, etc. can be used.

  As an example of the configuration of the lithium secondary battery as described above, for example, a molded product obtained by molding a mixture with a conductive agent into a pellet and drying under reduced pressure at 100 to 200 ° C. is used as a positive electrode for the battery. Examples include a negative electrode made of a foil, and an electrolytic solution in which lithium hexafluorophosphate is dissolved in a mixed solvent of ethylene carbonate and diethyl carbonate.

  As for the cubic spinel structure nickel-manganese based composite oxide of the present invention, a lithium-nickel-manganese based composite oxide using this as a raw material provides good battery characteristics. In addition, the method for producing a cubic spinel structure nickel-manganese composite oxide enables low-temperature synthesis as compared with a production method using a conventional solid phase reaction method. For this reason, it is possible to reduce manufacturing costs and equipment costs.

It is the XRD pattern and fitting result of the raw material nickel-manganese complex oxide obtained in the synthesis example. 2 is an XRD pattern of a nickel-manganese composite oxide of Example 1. FIG. 3 is an XRD pattern of a nickel-manganese composite oxide of Example 2. FIG. 3 is an XRD pattern of a nickel-manganese composite oxide of Example 3. FIG. 4 is an XRD pattern of a lithium-nickel-manganese composite oxide of Example 4. FIG. It is a charging / discharging curve of the lithium-nickel-manganese complex oxide of Example 4 (1st cycle). 6 is a relationship diagram of discharge capacity according to the cycle of the lithium-nickel-manganese composite oxide of Example 4. FIG. It is a charging / discharging curve of the lithium-nickel-manganese complex oxide of Example 5 (1st cycle). FIG. 6 is a relationship diagram of discharge capacity according to the cycle of the lithium-nickel-manganese composite oxide of Example 5. It is a charging / discharging curve of the lithium-nickel-manganese complex oxide of Example 6 (1st cycle). FIG. 10 is a relationship diagram of discharge capacity according to the cycle of the lithium-nickel-manganese composite oxide of Example 6. 7 is an XRD pattern of a nickel-manganese composite oxide of Example 7. FIG. It is an XRD pattern of the nickel-manganese composite compound of a comparative example.

  The present invention is specifically described by the following examples, but is not limited thereto.

  Various measurements were performed by the following methods.

<Powder X-ray diffraction measurement>
Using a general X-ray diffractometer (trade name: MXP-3, manufactured by Mac Science), powder X-ray diffraction measurement (XRD measurement) of the sample was performed. A CuKα ray (λ = 1.5405 mm) is used as the radiation source, the measurement mode is step scan, the scan condition is 0.04 ° per second, the measurement time is 3 seconds, and the measurement range is 2 ° to 5 ° to 100 °. Measured in range.

<Analysis of crystal structure (tetragonal)>
In the XRD pattern obtained by the XRD measurement under the above conditions, the structure of the tetragonal spinel crystal phase was refined by the Rietveld method. Lattice constants a and c were obtained by pattern fitting using analysis software Rietan-2000. For the oxyhydroxide and hydrotalcite type hydroxides which are by-products, the tetragonal spinel structure of 2θ = 19.2 ° ± 0.5 ° and 2θ = 11.7 ° ± 1.0 °, respectively. Their formation was confirmed by confirming diffraction peaks that could not be assigned.

<Analysis of crystal structure (cubic)>
In the XRD pattern obtained by the XRD measurement under the above conditions, the crystal structure was identified by comparison with the calculated value of the cubic spinel crystal phase.

<Measurement of crystallite diameter>
In the XRD pattern obtained by the XRD measurement under the above-mentioned conditions, Scherrer's formula [τ is obtained from the peak position and the half-value width of the peak that can be attributed to the cubic spinel structure of 2θ = 35.3 ° ± 0.5 °. = (Kλ) / (βCOSθ), k: form factor, λ: X-ray wavelength, β: peak full width at half maximum, θ: Bragg angle, τ: crystallite diameter] to obtain a crystallite diameter.

<Battery performance evaluation>
A battery characteristic test as a positive electrode of a lithium-nickel-manganese composite oxide was performed.

A mixture of lithium-nickel-manganese based composite oxide, polytetrafluoroethylene as a conductive agent, and acetylene black (trade name: TAB-2) is mixed at a weight ratio of 4: 1 and 1 ton / cm ² . After forming into a pellet shape on a mesh (made of SUS316) with pressure, it was dried under reduced pressure at 150 ° C. to produce a positive electrode for a battery. Electrolysis in which lithium hexafluorophosphate was dissolved in a mixed solvent of ethylene carbonate and diethyl carbonate at a concentration of 1 mol / dm ^{3 in} the obtained positive electrode for a battery, a negative electrode comprising a metal lithium foil (thickness 0.2 mm), and A battery was constructed using the liquid. Using this battery, the battery voltage was charged and discharged at room temperature between 4.9 V and 3.0 V at a constant current. The battery was charged / discharged at a current density of 0.4 mA / cm ² , and each specific capacity (mAh / g) was measured. The capacity retention rate was obtained from the formula [(discharge capacity at 50th cycle / discharge capacity at 10th cycle) ^1/40 ].

<XRD pattern fitting method>
Fitting of an XRD pattern of a tetragonal spinel type nickel-manganese composite oxide was performed by Rietan-2000.

Synthesis Example Nickel sulfate and manganese sulfate were dissolved in pure water to obtain an aqueous solution containing 1.5 mol / L nickel sulfate and 0.5 mol / L manganese sulfate, which was used as a metal salt aqueous solution (in a metal salt aqueous solution). The total concentration of all metals was 2.0 mol / L).

  Further, 200 g of pure water was put into a reaction vessel having an internal volume of 1 L, and then this was heated to 80 ° C. and maintained.

The aqueous metal salt solution was added to the reaction vessel at a supply rate of 0.28 g / min. Further, air was bubbled into the reaction vessel as an oxidizing agent at a supply rate of 0.2 L / min. 2 mol / L sodium hydroxide aqueous solution (caustic soda aqueous solution) was intermittently added so that the pH was 8.0 when supplying the metal salt aqueous solution and air, and 0.38 g of 3 mol / L ammonium sulfate solution was added. An equivalent amount of metal salt aqueous solution was added at / min to obtain a mixed aqueous solution, and a nickel-manganese composite oxide was precipitated in the mixed aqueous solution to obtain a slurry. At this time, the oxidation-reduction potential was 0.03V. The obtained slurry was filtered and washed, and then the wet cake was dried at 115 ° C. for 5 hours to obtain a nickel-manganese composite oxide [(Ni _0.24 Mn _0.76 ) ₃ O ₄ ].

  From the XRD pattern of the obtained nickel-manganese composite oxide, it was said that it was a single crystal phase having a substantially tetragonal spinel structure, although very weak diffuse scattering was observed in the vicinity of 2θ = 12 °.

  As a result of the XRD pattern and fitting of the nickel-manganese composite oxide (FIG. 1), it was found that the space group was I41 / amd, the lattice constant a was 5.8 Å, and the lattice constant c was 8.9 Å. .

Example 1
The tetragonal spinel-type nickel-manganese composite oxide obtained in the synthesis example was fired at 300 ° C. for 12 hours in an air stream to obtain a nickel-manganese composite oxide. The XRD pattern of the obtained nickel-manganese composite oxide is shown in FIG. 2, and can be said to be a single crystal phase having a substantially cubic spinel structure.

Example 2
A nickel-manganese composite oxide was obtained in the same manner as in Example 1 except that the firing temperature was 500 ° C. FIG. 3 shows the XRD pattern of the obtained nickel-manganese composite oxide, which was a cubic spinel single crystal phase.

Example 3
A nickel-manganese composite oxide was obtained in the same manner as in Example 1 except that the firing temperature was 900 ° C. The XRD pattern of the obtained nickel-manganese composite oxide is shown in FIG. 4 and was a cubic spinel single crystal phase.

Example 4
By mixing the cubic spinel structure nickel-manganese based composite oxide obtained in Example 1 and lithium carbonate, firing in an air stream at 800 ° C. for 10 hours, and then firing at 700 ° C. for 48 hours, A lithium-nickel-manganese composite oxide was synthesized. From the result of chemical composition analysis, it could be expressed as a composition formula Li ₂ NiMn ₃ O ₈ . The XRD pattern is shown in FIG.

  The battery performance of the lithium-nickel-manganese composite oxide was evaluated. FIG. 6 shows a charge / discharge curve. From the relationship diagram of the discharge capacity according to the cycle shown in FIG. 7, it was shown that the charge / discharge cycle performance was good because the capacity did not decrease until 50 cycles. The capacity retention rate obtained from the above calculation formula was 99.99%.

Example 5
A lithium-nickel-manganese composite oxide was synthesized in the same manner as in Example 4 except that the cubic spinel structure nickel-manganese composite oxide obtained in Example 2 was used. From the result of chemical composition analysis, it could be expressed as a composition formula Li ₂ NiMn ₃ O ₈ .

  The battery performance of the lithium-nickel-manganese composite oxide was evaluated. FIG. 8 shows a charge / discharge curve. From the relationship diagram of the discharge capacity by the cycle shown in FIG. 9, it was shown that the charge / discharge cycle performance was good because the capacity did not decrease until 50 cycles. The capacity retention rate obtained from the above calculation formula was 99.95%.

Example 6
A lithium-nickel-manganese composite oxide was synthesized in the same manner as in Example 4 except that the cubic spinel structure nickel-manganese composite oxide obtained in Example 3 was used. From the result of chemical composition analysis, it could be expressed as a composition formula Li ₂ NiMn ₃ O ₈ .

  The battery performance of the lithium-nickel-manganese composite oxide was evaluated. FIG. 10 shows a charge / discharge curve. From the relationship diagram of the discharge capacity according to the cycle shown in FIG. 11, it was shown that the charge / discharge cycle performance was good because no capacity decrease was observed up to 50 cycles. The capacity retention rate obtained from the above calculation formula was 99.99%.

Example 7
A nickel-manganese composite oxide was obtained in the same manner as in Example 1 except that the firing temperature was 250 ° C. FIG. 12 shows the XRD pattern of the obtained nickel-manganese composite oxide, which was a cubic spinel single crystal phase.

Comparative Example A nickel-manganese composite compound was obtained in the same manner as in Example 1 except that the firing temperature was 200 ° C. FIG. 13 shows the XRD pattern of the obtained nickel-manganese composite compound. In addition to the main component of the cubic spinel type oxide, peaks of tetragonal spinel type oxides are observed around 2θ = 31 ° and 34 °. Existed and became a mixed phase of cubic and tetragonal crystals.

  The cubic spinel structure nickel-manganese composite oxide of the present invention has a possibility of being used as a raw material for a positive electrode material for a Li secondary battery.

Claims (6)

Chemical composition formula is (Ni _{(0.25 ± α) -x} M1 _x Mn _{(0.75 ± α) -y} M2 _y ) ₃ O ₄ (where M1 and M2 are Mg, Al, Ti, V, Cr, respectively) , Fe, Co, Cu, Zn, and Zr, and 0 ≦ x ≦ 0.1, 0 ≦ y ≦ 0.25, and 0 ≦ α ≦ 0.05. A cubic spinel structure nickel-manganese composite oxide characterized in that the crystal structure is a cubic spinel structure and the crystallite diameter is 80 to 500 mm. Chemical composition formula is (Ni _{(0.25 ± α) -x} M1 _x Mn _{(0.75 ± α) -y} M2 _y ) ₃ O ₄ (where M1 and M2 are Mg, Al, Ti, V, Cr, respectively) , Fe, Co, Cu, Zn, and Zr, and 0 ≦ x ≦ 0.1, 0 ≦ y ≦ 0.25, and 0 ≦ α ≦ 0.05. A tetragonal spinel-type nickel-manganese composite oxide having a space group of I41 / amd, a lattice constant a of 5.7 to 5.9 格子, and a lattice constant c of 8.8 to 9.4Å at 300 ° C or higher. The cubic spinel structure nickel-manganese composite oxide according to claim 1, which is obtained by heat treatment. 3. The cubic spinel structure nickel-manganese composite oxide according to claim 1, wherein the space group is Fd-3m. Chemical composition formula is (Ni _{(0.25 ± α) -x} M1 _x Mn _{(0.75 ± α) -y} M2 _y ) ₃ O ₄ (where M1 and M2 are Mg, Al, Ti, V, Cr, respectively) , Fe, Co, Cu, Zn, and Zr, and 0 ≦ x ≦ 0.1, 0 ≦ y ≦ 0.25, and 0 ≦ α ≦ 0.05. A tetragonal spinel nickel-manganese composite oxide having a space group of I41 / amd, a lattice constant a of 5.7 to 5.9Å, and a lattice constant c of 8.8 to 9.4Å at 250 ° C or higher. The method for producing a cubic spinel structure nickel-manganese composite oxide according to any one of claims 1 to 3, wherein heat treatment is performed. Lithium-nickel obtained by mixing the cubic spinel type nickel-manganese composite oxide particle powder according to any one of claims 1 to 3 and a lithium compound and heat-treating the mixture. -Manganese complex oxide. A lithium secondary battery using the lithium-nickel-manganese composite oxide according to claim 5 as a positive electrode active material.

Images