CN110342588A - A kind of ternary cathode material of lithium ion battery and preparation method thereof - Google Patents

Abstract

The invention provides a method for preparing a lithium-ion battery ternary positive electrode material, which is characterized in that, calculated in parts by weight, the raw materials used for the preparation include: 21-42 parts of nickel salt; 11-21 parts of manganese salt; 11 parts of cobalt salt ～21 parts; 60～150 parts of precipitant; 10～25 parts of lithium salt; 20 parts of deionized water and 12 parts of ethylene glycol. The preparation method includes: step 1: adding nickel salt, manganese salt and cobalt salt into deionized water, stirring to form a salt solution, mixing a precipitant and ethylene glycol, stirring to form a precipitant solution, and mixing the salt solution and the precipitate Mix the agent solution, stir, carry out microwave hydrothermal reaction at 160-200 ° C for 30 minutes, wait for cooling and take it out to obtain a spindle-shaped precursor; Step 2: Mix the spindle-shaped precursor obtained in step 1 with lithium salt, put it in a horse Keep the temperature at 800-900° C. for 12-24 hours in a Furnace, and cool to obtain a ternary cathode material for a lithium-ion battery. The invention has uniform appearance, small particle size, high energy density, excellent cycle performance and short time consumption.

Description

A kind of lithium-ion battery ternary cathode material and preparation method thereof

technical field

The invention relates to a lithium ion battery ternary cathode material and a preparation method thereof.

Background technique

Lithium-ion battery is a clean and environmentally friendly secondary battery. Its positive electrode material directly determines the performance of the battery, and the nickel-cobalt-manganese ternary positive electrode material is a high-energy density, low-cost lithium-ion battery positive electrode material, which can be widely used in electronic devices and electric vehicles.

At present, the main preparation processes of nickel-cobalt-manganese ternary materials include coprecipitation method, spray drying method and hydrothermal method. The co-precipitation method can be produced only at a temperature below 100°C, but it has strict requirements on pH, stirring speed, etc., and requires strict control of conditions; the spray drying method has a high degree of automation and a short preparation cycle, but the output rate of its raw material input Low; the hydrothermal method is simple to operate and easy to prepare materials, but its synthesis takes 18 to 24 hours, wasting a lot of energy, and the morphology and particle size are poor. Patent CN105070903A adopts co-precipitation method to prepare ternary material precursor. Although the content of impurities is reduced, it takes as long as 15-30 hours and the particle size is not uniform. In the patent CN107464929A, a ternary material with stable performance was obtained by spray-drying blending method. However, its particle size is relatively large and uneven in the range of 5-20 μm, and its first-cycle charge capacity is only 157mAh·g ^-1 .

Based on the above background. There is an urgent need to develop a nickel-cobalt-manganese ternary cathode material that can be rapidly prepared, has better morphology, relatively uniform particle size of less than 5 μm, and high capacity (higher than 180mAh·g ^-1 ).

Contents of the invention

In view of the problems that the existing nickel-cobalt-manganese ternary materials take a long time to prepare, have different microscopic shapes, and relatively large particle sizes, resulting in poor cycle performance, the purpose of the present invention is to provide uniform shape, small particle size, A lithium-ion battery nickel-cobalt-manganese ternary positive electrode material with high energy density, excellent cycle performance and short time consumption and a preparation method thereof.

In order to achieve the above object, the invention provides a method for preparing a lithium-ion battery ternary positive electrode material, which is characterized in that, calculated in parts by weight, the raw materials used for its preparation include:

Described preparation method comprises:

Step 1: Add nickel salt, manganese salt and cobalt salt to deionized water, stir to form a salt solution, mix the precipitant and ethylene glycol, stir to form a precipitant solution, mix the salt solution and the precipitant solution, stir, and Perform microwave hydrothermal reaction at 160-200°C for 25-35 minutes, wait for cooling and take it out to obtain a spindle-shaped precursor of LiMn _0.25 Ni _0.5 Co _0.25 O ₂ ;

Step 2: Mix the spindle-shaped precursor of LiMn _0.25 Ni _0.5 Co _0.25 O ₂ obtained in Step 1 with lithium salt, put it in a muffle furnace, keep it at 800-900°C for 12-24h, and cool to obtain LiMn _0.25 Ni _0.5 Co _0.25 O ₂ .

Preferably, the preparation raw materials include:

Preferably, the nickel salt is nickel sulfate hexahydrate (NiSO ₄ ·6H ₂ O), nickel acetate tetrahydrate (Ni(CH ₃ COO) ₂ ·4H ₂ O), nickel chloride hexahydrate (NiCl ₂ ·6H ₂ O) and nickel nitrate hexahydrate (Ni(NO ₃ ) ₂ ·6H ₂ O) or two or more.

Preferably, the manganese salt is manganese sulfate tetrahydrate (MnSO ₄ ·4H ₂ O), manganese acetate tetrahydrate (Mn(CH ₃ COO) ₂ ·4H ₂ O), manganese chloride tetrahydrate (MnCl ₂ 4H ₂ O) and manganese nitrate tetrahydrate (Mn(NO ₃ ) ₂ 4H ₂ O) or two or more.

Preferably, the cobalt salt is cobalt sulfate heptahydrate (CoSO ₄ ·7H ₂ O), cobalt acetate tetrahydrate (Co(CH ₃ COO) ₂ ·4H ₂ O), cobalt chloride hexahydrate (CoCl ₂ ·6H ₂ O) and cobalt nitrate hexahydrate (Co(NO ₃ ) ₂ ·6H ₂ O) or two or more.

Preferably, the precipitant is one or more of dimethyl carbonate (DMC), dimethyl oxalate (DMO) and urea (CO(NH ₂ ) ₂ ).

Preferably, the lithium salt is one or more of lithium hydroxide monohydrate (LiOH·H ₂ O), lithium carbonate (Li ₂ CO ₃ ) and lithium acetate (CH ₃ COOLi).

Preferably, the reaction time in step 1 is 25-35 minutes.

Preferably, in the step 2, the excess of lithium salt is 5-10%.

Preferably, the molar ratios of Mn, Ni and Co contained in the manganese salt, nickel salt and cobalt salt are 1:2:1.

The present invention also provides the lithium ion battery ternary positive electrode material prepared by the above-mentioned preparation method of the lithium ion battery ternary positive electrode material.

Compared with the prior art, the present invention has the following beneficial effects:

The present invention uses microwaves to form a uniform thermal field to increase the collision between particles, and regulates the growth process to make the microwave hydrothermal method with uniform morphology of the generated material replace the ordinary hydrothermal method with uneven resistance heat, and prepares 2-5 μm shuttle-shaped particles, and it takes only about 30 minutes, which saves energy and improves time efficiency.

Further, the process of the present invention is simple, and the LiMn _0.25 Ni _0.5 Co _0.25 O ₂ prepared under the high-temperature solid phase has a uniform appearance, and the surface is covered with a layer of tiny uniform particles with a particle diameter of about 2-5 μm and a large specific surface area, which makes It has high energy density and good cycle performance.

The invention is simple, easy to implement and environmentally friendly, and the prepared nickel-cobalt-manganese ternary material LiMn _0.25 Ni _0.5 Co _0.25 O ₂ has a particle size of 2-5 μm and a specific surface area of up to 1.60-1.67 m ² ·g ^-1 . It has a relatively high initial discharge capacity of 180～185mAh·g ^-1 under ordinary cycles, and a relatively high specific capacity of 150～156mAh·g ^-1 after 100 cycles at 1C (20mA·g ^-1 ). There is a retention rate of over 84%. After 100 cycles at 10C (discharge capacity of 200mA·g ^-1 ), there is still a good rate performance of 99～105mAh·g ^-1 .

Description of drawings

Figure 1 is a scanning electron microscope image of a ternary cathode material for a lithium-ion battery.

Fig. 2 is an X-ray diffraction spectrum of a lithium-ion battery ternary cathode material.

Detailed ways

Below in conjunction with specific embodiment, further illustrate the present invention. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the teachings of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

Except for the following special instructions, the raw materials used in each embodiment of the present invention were all purchased from Shanghai Sinopharm Chemical Reagent Co., Ltd.;

The preparation and testing instruments adopted in this patent are as follows:

Microwave digestion instrument (WX-6000), the reaction temperature is 160-200°C, and the reaction time is 30 minutes. X-ray diffraction (D/max-2200-PC), test conditions 10°～80°, 4° per minute. Scanning electron microscope (SIGMA, ZEISSmicroscope). Thermogravimetric/differential thermal analysis (TGA/SDTA851), the test condition is 25℃～1000℃. Specific surface test (ASAP2020). Landian (Wuhan LAND), keep the room temperature at 25°C during the test.

Example 1

A lithium-ion battery ternary positive electrode material, the raw materials used in its preparation are calculated in parts by weight, and its composition and content are as follows:

Wherein, the nickel salt is nickel sulfate hexahydrate;

Described manganese salt is manganese sulfate tetrahydrate;

Described cobalt salt is cobalt sulfate heptahydrate;

Described precipitation agent is dimethyl oxalate;

Described lithium salt is lithium acetate;

The above-mentioned ternary positive electrode material for a lithium ion battery and a preparation method thereof specifically include the following steps:

(1) Preparation of precursors: Add nickel sulfate hexahydrate, manganese sulfate tetrahydrate and cobalt sulfate heptahydrate into deionized water in proportion, and stir continuously to directly form a transparent salt solution. Mix dimethyl oxalate and ethylene glycol and stir constantly to form a transparent and clear precipitant solution. After that, mix the salt solution and the precipitant solution, stir continuously until it is clear and uniform, add the stirred solution into the microwave hydrothermal lining, put it into the microwave hydrothermal system, directly raise the temperature to 180°C, and then keep it warm for microwave hydrothermal reaction 35 minutes, then wait for cooling to below 60°C and take it out. In the microwave hydrothermal reaction, the spindle-shaped precursor of LiMn _0.25 Ni _0.5 Co _0.25 O ₂ was formed;

(2) Synthesis of LiMn _0.25 Ni _0.5 Co _0.25 O ₂ : Mix the precursor and lithium acetate obtained in step (1) uniformly in proportion, put them into a muffle furnace and raise the temperature to 900 °C at a heating rate of 5 °C/min Keep it warm for 20 hours, then cool to room temperature and take it out to obtain LiMn _0.25 Ni _0.5 Co _0.25 O ₂ .

Example 2

A lithium-ion battery ternary positive electrode material, the raw materials used in its preparation are calculated in parts by weight, and its composition and content are as follows:

Wherein, the nickel salt is nickel acetate tetrahydrate;

Described manganese salt is manganese acetate tetrahydrate;

Described cobalt salt is cobalt acetate tetrahydrate;

Described precipitation agent is dimethyl carbonate;

Described lithium salt is lithium hydroxide;

The above-mentioned ternary positive electrode material for a lithium ion battery and a preparation method thereof specifically include the following steps:

(1) Preparation of precursors: Add nickel acetate tetrahydrate, manganese acetate tetrahydrate and cobalt acetate tetrahydrate into deionized water according to the routine, and stir continuously to directly form a transparent salt solution. Mix dimethyl carbonate and ethylene glycol with constant stirring to form a transparent and clear precipitant solution. Afterwards, mix the salt solution and the precipitant solution, stir continuously until it is clear and uniform, add the stirred solution into the microwave hydrothermal lining, put it into the microwave hydrothermal system, directly raise the temperature to 190°C, and then keep it warm for microwave hydrothermal reaction After 25 minutes, wait for it to cool below 60°C and take it out. In the microwave hydrothermal reaction, the spindle-shaped precursor of LiMn _0.25 Ni _0.5 Co _0.25 O ₂ was formed;

(2) Synthesis of LiMn _0.25 Ni _0.5 Co _0.25 O ₂ : The precursor obtained in step (1) was uniformly mixed with lithium hydroxide monohydrate in proportion, and placed in a muffle furnace at a heating rate of 5 °C/min. The temperature was raised to 850° C. and kept for 12 hours, and then cooled to room temperature and taken out to obtain LiMn _0.25 Ni _0.5 Co _0.25 O ₂ .

Example 3

A lithium-ion battery ternary positive electrode material, the raw materials used in its preparation are calculated in parts by weight, and its composition and content are as follows:

Wherein, described nickel salt is nickel chloride hexahydrate;

Described manganese salt is manganese chloride tetrahydrate;

Described cobalt salt is cobalt chloride hexahydrate;

Described precipitation agent is urea;

Described lithium salt is lithium carbonate;

The above-mentioned ternary positive electrode material for a lithium ion battery and a preparation method thereof specifically include the following steps:

(1) Preparation of precursors: Add nickel chloride hexahydrate, manganese chloride tetrahydrate and cobalt chloride hexahydrate into deionized water in proportion, and stir continuously to directly form a transparent salt solution. Mix urea and ethylene glycol with constant stirring to form a transparent and clear precipitant solution. After that, mix the salt solution and the precipitant solution, stir continuously until it is clear and uniform, add the stirred solution into the microwave hydrothermal lining, put it into the microwave hydrothermal system, directly raise the temperature to 200°C, and then keep it warm for microwave hydrothermal reaction After 30 minutes, wait for it to cool below 60°C and take it out. In the microwave hydrothermal reaction, the spindle-shaped precursor of LiMn _0.25 Ni _0.5 Co _0.25 O ₂ was formed;

(2) Synthesis of LiMn _0.25 Ni _0.5 Co _0.25 O ₂ : The precursor obtained in step (1) was uniformly mixed with lithium carbonate in proportion, and put into a muffle furnace to raise the temperature to 800°C at a heating rate of 5°C/min. Keep it warm for 16 hours, then cool to room temperature and take out to obtain LiMn _0.25 Ni _0.5 Co _0.25 O ₂ .

LiMn _0.25 Ni _0.5 Co _0.25 O obtained in Example ₃ shows the situation of the material at various stages when it is generated by thermogravimetric and differential thermal analysis, and also determines the temperature range of material synthesis for us; The material maintains an excellent spindle shape, and the precursor is covered with a layer of fine particles. Obviously, the morphology of such a spindle-shaped material covered with a layer of particles is more conducive to the penetration of the electrolyte into the electrode material. The electrolyte ensures a larger contact area (see Figure 1); it is pure and without any impurities through XRD analysis, and the two pairs of peaks are highly split, and the layered structure of the sample is good, in which narrow and sharp peaks show The crystallinity of the material is very high (see Figure 2); the EDS mapping element analysis proves that the three elements are uniformly distributed in a layered structure with excellent morphology; the CV cyclic voltammetry test also reveals the complete electrical properties of the material. The chemical reaction explains the mechanism of the charge-discharge cycle of the material; the prepared LiMn _0.25 Ni _0.5 Co _0.25 O ₂ has a high discharge capacity of 180～185mAh g ^-1 under normal cycle, and it is cycled at 1C for 100 After lapping, there is still a high specific capacity of 150～156mAh·g ^-1 and a retention rate of more than 84%. It also has a good rate performance of 99～105mAh·g ^-1 at 10C.

The above content is only a basic description of the concept of the present invention, and any equivalent transformation made according to the technical solution of the present invention shall fall within the scope of protection of the present invention.

Claims (9)

1. A preparation method for a lithium-ion battery ternary positive electrode material, characterized in that, calculated in parts by weight, the raw materials used for its preparation include: Described preparation method comprises: Step 1: Add nickel salt, manganese salt and cobalt salt to deionized water, stir to form a salt solution, mix the precipitant and ethylene glycol, stir to form a precipitant solution, mix the salt solution and the precipitant solution, stir, and Perform microwave hydrothermal reaction at 160-200°C for 25-35 minutes, wait for cooling and take it out to obtain a spindle-shaped precursor of LiMn _0.25 Ni _0.5 Co _0.25 O ₂ ; Step 2: Mix the spindle-shaped precursor of LiMn _0.25 Ni _0.5 Co _0.25 O ₂ obtained in Step 1 with lithium salt, put it in a muffle furnace, keep it at 800-900°C for 12-24h, and cool to obtain LiMn _0.25 Ni _0.5 Co _0.25 O ₂ . 2. the preparation method of lithium ion battery ternary cathode material as claimed in claim 1, is characterized in that, described preparation raw material comprises: 3. the preparation method of lithium ion battery ternary cathode material as claimed in claim 1 is characterized in that, described nickel salt is nickel sulfate hexahydrate, nickel acetate tetrahydrate, nickel chloride hexahydrate and nitric acid One type or two or more types of nickel hexahydrate. 4. the preparation method of lithium ion battery ternary cathode material as claimed in claim 1 is characterized in that, described manganese salt is manganese sulfate tetrahydrate, manganese acetate tetrahydrate, manganese chloride tetrahydrate and nitric acid One or more kinds of manganese tetrahydrate. 5. the preparation method of lithium ion battery ternary cathode material as claimed in claim 1 is characterized in that, described cobalt salt is cobalt sulfate heptahydrate, cobalt acetate tetrahydrate, cobalt chloride hexahydrate and nitric acid One type or two or more types of cobalt hexahydrate. 6. The preparation method of lithium ion battery ternary cathode material as claimed in claim 1, is characterized in that, described precipitation agent is one or more in dimethyl carbonate, dimethyl oxalate and urea. 7. the preparation method of lithium ion battery ternary cathode material as claimed in claim 1 is characterized in that, described lithium salt is one or more in lithium hydroxide monohydrate, lithium carbonate and lithium acetate . 8 . The method for preparing a ternary positive electrode material for a lithium ion battery according to claim 1 , wherein the lithium salt is in excess of 5-10% in the step 2. 9 . 9. The lithium ion battery ternary positive electrode material prepared by the preparation method of the lithium ion battery ternary positive electrode material described in any one of claims 1-8.