CN109873140B - Graphene composite ternary cathode material of lithium ion battery and preparation method of graphene composite ternary cathode material - Google Patents

Abstract

The invention discloses a lithium ion battery graphene composite ternary cathode material and a preparation method thereof. The invention can integrate the advantages of two materials by compounding, improve the electronic conductivity and the ionic conductivity, improve the output power density of the battery, and improve the structural stability of the ternary material, thereby obtaining the composite anode material with better cyclicity, higher capacity and higher energy density.

Description

Graphene composite ternary cathode material of lithium ion battery and preparation method of graphene composite ternary cathode material

Technical Field

The invention belongs to the technical field of battery materials, and particularly relates to a graphene composite ternary cathode material of a lithium ion battery and a preparation method thereof.

Background

The lithium ion battery is a new generation secondary battery developed on the basis of the primary lithium battery and widely used for small-sized portable electronic communication productsAnd electric vehicles. Currently, lithium ion battery anode materials which are industrialized mainly include lithium cobaltate, modified lithium manganate, lithium iron phosphate, ternary materials and the like. Lithium cobaltate has stable performance, but has high cost and toxic cobalt element, and may cause environmental pollution. Although the spinel type lithium manganate is low in price, the spinel type lithium manganate has poor cycle performance due to Jahn-Teller effect, and the electrochemical performance of the spinel type lithium manganate is rapidly attenuated due to the problem of manganese dissolution at high temperature. Lithium iron phosphate has poor conductivity, poor product batch disposability and poor low-temperature performance, and the problem that the dissolution of trace iron may cause short circuit of the battery exists. Therefore, it was found that LiNi was used as a material for the production of a polymer_xCo_yMn_1-x-yO₂The layered nickel oxide cobalt manganese series material (ternary material for short) has the advantages of the materials, overcomes the defects to a certain extent, has the characteristics of high specific capacity, stable cycle performance, relatively low cost, good safety performance and the like, and is considered as an ideal choice for a hybrid power supply. But at the same time, the method also has the defects of lower conductivity, fast capacity attenuation, poor rate capability and the like.

The preparation method of the prior ternary material mainly comprises a high-temperature solid phase method, a coprecipitation method, a sol-gel method, a template method and the like. The invention uses the template method to prepare the nickel-cobalt-manganese-lithium oxide material with uniform particles, thereby simplifying the preparation process. The size of the material prepared by the template method can be controlled, the problem of uneven granularity of the traditional solid phase method is solved, and the prepared material has high purity, small particle size, narrow distribution and good sintering performance.

The ternary positive electrode material integrates LiNiO₂、LiCoO₂、LiMnO₂The advantages of the three positive electrode materials are considered to be one of the most potential widely applied positive electrode materials. The nickel-cobalt-manganese-lithium oxide ternary material has excellent performance which is paid attention to by a plurality of research institutions at home and abroad, is widely used in small electronic products, has a good development trend on large automobile power batteries, and has good application prospect. But simultaneously, the method also has the defects of lower conductivity, quick capacity attenuation, poor rate capability and the like, and in order to obtain a more excellent ternary cathode material, the lithium nickel cobalt manganese oxide is subjected toAnd (4) carrying out row doping and cladding. The crystal lattice is distorted to a certain extent through ion doping, certain defects are generated, and the electronic conductivity and the ion diffusion rate are improved, so that the rate capability and the cycle performance are improved.

Graphene, as a two-dimensional carbon nanomaterial, has a hexagonal honeycomb-shaped cavity structure of a two-dimensional monolayer and excellent physicochemical properties, such as a high specific surface area, a high electronic conductivity, excellent mechanical properties, good chemical stability, and the like, and thus is widely used in lithium ion batteries. In recent years, a lot of researches show that graphene can form a conductive network in a composite cathode material to improve the conductivity of the composite cathode material, and is helpful for shortening the diffusion path of lithium ions and greatly improving the high-rate charge and discharge performance of the cathode material, which are very important for nickel-cobalt-manganese-lithium oxide.

Disclosure of Invention

The invention aims at a ternary layered positive electrode material LiNi_xCo_l-x-y-zMn_yAl_zO₂The lithium ion battery graphene composite ternary cathode material has the advantages of poor repeatability and rate capability, simple process, high safety and good stability.

The invention is realized by the following technical scheme:

a lithium ion battery graphene composite ternary cathode material is prepared by putting aluminum element into nickel cobalt manganese lithium oxide crystal lattice to replace Co on partial position³⁺And then mixing the aluminum-doped nickel-cobalt-manganese-lithium oxide with graphene, and preparing the mixture by a hydrothermal method.

The invention also provides a preparation method of the graphene composite ternary cathode material for the lithium ion battery, which comprises the following steps:

(1) dissolving potassium permanganate in certain deionized water, dropwise adding concentrated hydrochloric acid in a certain molar ratio, stirring for 15 minutes, placing the mixture into a reaction kettle for hydrothermal reaction, cooling, centrifuging, washing and drying to obtain brown manganese dioxide, and then calcining for 6 hours at 350 ℃ in a muffle furnace to obtain a solid product A;

(2) mixing the solid product A obtained in the step 1 with a nickel source, a cobalt source, an aluminum source and lithiumMixing and adding salt into a mixed solution of water and absolute ethyl alcohol according to a certain molar ratio, performing ultrasonic dispersion for 0.5-1 hour, stirring and evaporating to dryness to obtain a solid mixture B, grinding the solid mixture B, putting the ground mixture B into a crucible, and calcining to obtain the aluminum-doped nickel-cobalt-manganese-lithium oxide LiNi_xCo_{l-x-y- z}Mn_yAl_zO₂A positive electrode material;

(3) mixing graphene and LiNi prepared in the step 2_xCo_l-x-y-zMn_yAl_zO₂The anode material is put into water/glycol solution with the concentration of 0.01-0.02mol/L, ultrasonically dispersed for 0.5-2 hours, stirred, put into a reaction kettle for hydrothermal reaction, cooled and centrifugally washed to obtain LiNi_xCo_l-x-y-zMn_yAl_zO₂ A graphene composite positive electrode material.

The temperature of the hydrothermal reaction in the step 1 is 140-160 ℃, the reaction time is 8-14 hours, the drying time is 8-12 hours, and the calcining temperature rise rate is 2 ℃/min.

In the step 2, the cobalt source is one or more of cobalt nitrate, cobalt acetate and cobalt chloride; the nickel source is one or more of nickel nitrate, nickel acetate and nickel chloride; the aluminum source is one or more of aluminum nitrate and aluminum chloride; the lithium salt is one or more of lithium carbonate, lithium acetate and lithium nitrate.

And 2, dissolving lithium salt, a cobalt source, a nickel source, an aluminum source and brown manganese dioxide in a mixed solution of water and absolute ethyl alcohol according to a certain molar ratio, and keeping the concentration at 0.1-0.15 mol/L.

The volume ratio of water to absolute ethyl alcohol in the mixed solution of water and absolute ethyl alcohol in the step 2 is 1: 0-10.

The evaporation temperature in the step 2 is 60-75 ℃, the calcination process is to heat to 400-500 ℃ for calcination for 5-8h, then to 750-850 ℃ for calcination for 10-20h, and the heating rate is 2 ℃/min.

The aluminum-doped nickel cobalt manganese lithium oxide LiNi obtained in the step 2_xCo_l-x-y-zMn_yAl_zO₂A positive electrode material, wherein 0<x<0.5，0<y<0.5，0<z<0.05。

The dosage of the graphene in the step 3 accounts for LiNi_xCo_l-x-y-zMn_yAl_zO₂1-10% of the mass, wherein the volume ratio of water to glycol in the mixed solution of water and glycol is 1-2: 1.

the temperature of the hydrothermal reaction in the step 3 is 120-140 ℃, the reaction time is 10-12 hours, the drying temperature is 70-80 ℃, and the drying time is 8-12 hours.

The invention has the advantages that:

1. the composite anode material of the invention is LiNi with better cycle performance and better rate performance_xCo_{l-x-y- z}Mn_yAl_zO₂A graphene composite positive electrode material.

2. The invention is simple and easy to operate, has high production efficiency, reduces the production procedures, saves the production cost, and greatly improves the capacity, the rate capability and the cycle performance of the battery compared with the material which is not modified.

3. Hydrothermal recombination method for improving LiNi_xCo_l-x-y-zMn_yAl_zO₂Adhesion to graphene to make LiNi_xCo_l-x-y-zMn_yAl_zO₂The graphene sheets are uniformly dispersed among the graphene sheets to form a conductive network, so that the cycle performance and the rate capability of the lithium ion battery can be improved.

Drawings

FIG. 1 shows LiNi_1/3Co_1/3Mn_1/3O₂And LiNi_1/3Co_1/3-0.03Mn_1/3Al_0.03O₂XRD pattern of (a).

FIG. 2 shows LiNi_1/3Co_1/3-0.05Mn_1/3Al_0.05O₂And LiNi_1/3Co_1/3-0.05Mn_1/3Al_0.05O₂Raman spectrum of graphene.

FIG. 3 shows LiNi_1/3Co_1/3Mn_1/3O₂、LiNi_1/3Co_1/3-0.05Mn_1/3Al_0.05O₂And LiNi_1/3Co_1/3-0.05Mn_{1/ 3}Al_0.05O₂First charge-discharge curve of graphene at 0.1C.

FIG. 4 shows LiNi_1/3Co_1/3-0.05Mn_1/3Al_0.05O₂And LiNi_1/3Co_1/3-0.05Mn_1/3Al_0.05O₂A cycle performance diagram of the graphene composite anode material.

FIG. 5 shows LiNi prepared in example 4_1/3Co_1/3-0.05Mn_1/3Al_0.05O₂SEM image of/graphene composite cathode material.

Detailed Description

The technical scheme of the invention is further explained by combining the specific examples as follows:

example 1

The preparation method of the nickel-cobalt-manganese-lithium oxide cathode material of the lithium ion battery in the embodiment comprises the following steps:

(1) weighing 0.79g of potassium permanganate, dissolving in 50ml of deionized water, stirring for 15 minutes to completely dissolve the potassium permanganate, then dropwise adding 2ml of 37% hydrochloric acid, continuously stirring for 15 minutes, then transferring to a reaction kettle, reacting for 12 hours at 140 ℃, centrifuging, washing, drying for 12 hours at 70 ℃, transferring the obtained product to a crucible, calcining for 6 hours at 350 ℃ in a muffle furnace to obtain the required MnO₂；

(2) 0.5481g of lithium nitrate, 0.2174g of manganese dioxide, 0.7276g of cobalt nitrate nonahydrate and 0.7270g of nickel nitrate nonahydrate are weighed and dissolved in a mixed solution of 50ml of water and 50ml of ethanol, and in order to make up for the loss of a lithium source in the calcining process, the lithium nitrate is excessive by 6 percent; performing ultrasonic treatment for 1 hour, continuing stirring for 6 hours, continuing stirring at 70 ℃ until the mixture is dried, grinding the dried solid, putting the ground solid into a crucible, putting the crucible into a muffle furnace, heating to 480 ℃ at a heating rate of 2 ℃/min in the air atmosphere, calcining for 5 hours, continuing heating to 850 ℃, calcining for 16 hours, cooling to room temperature along with the furnace, taking out a sample, and grinding again to obtain LiNi_1/3Co_1/3Mn_1/3O₂Powder;

the obtained LiNi_1/3Co_1/3Mn_1/3O₂With acetylene black and polyvinylidene fluoride (PVDF) at 8: 1: 1, rolling into a film with the thickness of 120 mu m, and performing vacuum drying at 120 ℃ for 10 hours to obtain the anode of the experimental half cell; using 1mol/L LiPF₆Ethylene Carbonate (EC) -dimethyl carbonate (DMC) (EC to DMC volume ratio 1: 1) electrolyte, in a dry argon-filled glove box, with a metal lithium sheet as the negative electrode, assembled into a battery. LiNi prepared in this example_1/3Co_{1/ 3}Mn_1/3O₂The button cell which is taken as the anode and takes the lithium sheet as the cathode is charged under constant current-constant voltage under 0.1C multiplying power within the voltage range of 2.5-4.3V, the first discharge specific capacity is 175mAh/g when the battery is discharged under constant current under 0.1C multiplying power, but the capacity is only 157mAh/g after 30 cycles.

Example 2

The preparation method of the aluminum-doped nickel-cobalt-manganese-lithium oxide cathode material for the lithium ion battery in the embodiment comprises the following steps:

(1) weighing 0.79g of potassium permanganate, dissolving in 50ml of deionized water, stirring for 15 minutes to completely dissolve the potassium permanganate, then dropwise adding 2ml of 37% hydrochloric acid, continuously stirring for 15 minutes, then transferring to a reaction kettle, reacting for 12 hours at 140 ℃, centrifuging, washing, drying for 12 hours at 70 ℃, transferring the obtained product to a crucible, calcining for 6 hours at 350 ℃ in a muffle furnace to obtain the required MnO₂；

(2) 0.5481g of lithium nitrate, 0.2174g of manganese dioxide, 0.6620g of cobalt nitrate nonahydrate, 0.7270g of nickel nitrate nonahydrate and 0.0844g of aluminum nitrate nonahydrate are weighed and dissolved in a mixed solution of 50ml of water and 50ml of ethanol, and in order to compensate the loss of a lithium source in the calcining process, the lithium nitrate is excessive by 6 percent; performing ultrasonic treatment for 1 hour, continuing stirring for 6 hours, continuing stirring at 70 ℃ until the mixture is dried, grinding the dried solid, putting the ground solid into a crucible, putting the crucible into a muffle furnace, heating to 480 ℃ at a heating rate of 2 ℃/min in the air atmosphere, calcining for 5 hours, continuing heating to 850 ℃, calcining for 16 hours, cooling to room temperature along with the furnace, taking out a sample, and grinding again to obtain LiNi_1/3Co_1/3-0.03Mn_1/3Al_0.03O₂And (3) powder.

LiNi prepared by experiments_1/3Co_1/3Mn_1/3O₂And LiNi_1/3Co_1/3-0.03Mn_1/3Al_0.03O₂The X-ray diffraction pattern of (A) is shown in FIG. 1. As can be seen from FIG. 1, LiNi was produced_1/3Co_1/3-0.05Mn_1/3Al_0.05O₂Positive electrode material and undoped LiNi_1/3Co_1/3Mn_1/3O₂The XRD patterns of the materials are the same, and no impurity peak appears, which probably means that Al enters LiNi_1/3Co_1/3Mn_{1/ 3}O₂In the lattice, Co is substituted for some positions³⁺This indicates that the doping does not affect the bulk layer structure.

The obtained LiNi_1/3Co_1/3-0.03Mn_1/3Al_0.03O₂With acetylene black and polyvinylidene fluoride (PVDF) at 8: 1: 1, rolling into a film with the thickness of 120 mu m, and performing vacuum drying at 120 ℃ for 10 hours to obtain the anode of the experimental half cell; using 1mol/L LiPF₆Ethylene Carbonate (EC) -dimethyl carbonate (DMC) (EC to DMC volume ratio 1: 1) electrolyte, in a dry argon-filled glove box, with a metal lithium sheet as the negative electrode, assembled into a battery. LiNi prepared in this example_1/3Co_1/3-0.03Mn_1/3Al_0.03O₂The button cell which is taken as the anode and the lithium sheet as the cathode is charged under constant current-constant voltage at 0.1C multiplying power within the voltage range of 2.5-4.3V, the first discharge specific capacity is 186mAh/g when the battery is discharged under constant current at 0.1C multiplying power, but the capacity is 175mAh/g after 30 cycles.

Example 3

The preparation method of the aluminum-doped nickel-cobalt-manganese-lithium oxide cathode material for the lithium ion battery in the embodiment comprises the following steps:

(1) weighing 0.79g of potassium permanganate, dissolving in 50ml of deionized water, stirring for 15 minutes to completely dissolve the potassium permanganate, then dropwise adding 2ml of 37% hydrochloric acid, continuing stirring for 15 minutes, then transferring to a reaction kettle, reacting at 140 ℃ for 12 hours, centrifuging, washing, drying at 70 ℃ for 12 hours, transferring the obtained product to a crucible, and finally drying in the presence of deionized waterCalcining the mixture for 6 hours in a muffle furnace at 350 ℃ to obtain the required MnO₂；

(2) 0.5481g of lithium nitrate, 0.2174g of manganese dioxide, 0.6183g of cobalt nitrate nonahydrate, 0.7270g of nickel nitrate nonahydrate and 0.1406g of aluminum nitrate nonahydrate are weighed and dissolved in a mixed solution of 50ml of water and 50ml of ethanol, and in order to compensate the loss of a lithium source in the calcining process, the lithium nitrate is excessive by 6 percent; performing ultrasonic treatment for 1 hour, continuing stirring for 6 hours, continuing stirring at 70 ℃ until the mixture is dried, grinding the dried solid, putting the ground solid into a crucible, putting the crucible into a muffle furnace, heating to 480 ℃ at a heating rate of 2 ℃/min in the air atmosphere, calcining for 5 hours, continuing heating to 850 ℃, calcining for 16 hours, cooling to room temperature along with the furnace, taking out a sample, and grinding again to obtain LiNi_1/3Co_1/3-0.05Mn_1/3Al_0.05O₂And (3) powder.

The obtained LiNi_1/3Co_1/3-0.05Mn_1/3Al_0.05O₂With acetylene black and polyvinylidene fluoride (PVDF) at 8: 1: 1, rolling into a film with the thickness of 120 mu m, and performing vacuum drying at 120 ℃ for 10 hours to obtain the anode of the experimental half cell; using 1mol/L LiPF₆Ethylene Carbonate (EC) -dimethyl carbonate (DMC) (EC to DMC volume ratio 1: 1) electrolyte, in a dry argon-filled glove box, with a metal lithium sheet as the negative electrode, assembled into a battery. LiNi prepared in this example_1/3Co_1/3-0.05Mn_1/3Al_0.05O₂The button cell which is taken as the anode and the lithium sheet as the cathode is charged under constant current-constant voltage at 0.1C multiplying power within the voltage range of 2.5-4.3V, the first discharge specific capacity is 186mAh/g when the battery is discharged under constant current at 0.2C multiplying power, but the capacity is only 178mAh/g after 30 cycles.

Example 4

The preparation method of the aluminum-doped nickel-cobalt-manganese-lithium oxide/graphene positive electrode material for the lithium ion battery in the embodiment comprises the following steps:

(1) weighing 0.79g of potassium permanganate, dissolving in 50ml of deionized water, stirring for 15 minutes to completely dissolve the potassium permanganate, then dropwise adding 2ml of 37% hydrochloric acid, continuing stirring for 15 minutes, then transferring to a reaction kettle, and reacting for 12 hours at 140 DEG CThen, the resulting product was centrifuged, washed, dried at 70 ℃ for 12 hours, transferred to a crucible, and calcined in a muffle furnace at 350 ℃ for 6 hours to obtain the desired MnO₂；

(2) 0.5481g of lithium nitrate, 0.2174g of manganese dioxide, 0.6183g of cobalt nitrate nonahydrate, 0.7270g of nickel nitrate nonahydrate and 0.1406g of aluminum nitrate nonahydrate are weighed and dissolved in a mixed solution of 50ml of water and 50ml of ethanol, and in order to compensate the loss of a lithium source in the calcining process, the lithium nitrate is excessive by 6 percent; performing ultrasonic treatment for 1 hour, continuing stirring for 6 hours, continuing stirring at 70 ℃ until the mixture is dried, grinding the dried solid, putting the ground solid into a crucible, putting the crucible into a muffle furnace, heating to 480 ℃ at a heating rate of 2 ℃/min in the air atmosphere, calcining for 5 hours, continuing heating to 850 ℃, calcining for 16 hours, cooling to room temperature along with the furnace, taking out a sample, and grinding again to obtain LiNi_1/3Co_1/3-0.05Mn_1/3Al_0.05O₂Powder;

(3) weighing the obtained LiNi_1/3Co_1/3-0.05Mn_1/3Al_0.05O₂Dispersing 0.3g of powder and 0.009g of graphene in a mixed solution of 30ml of deionized water and 20ml of ethylene glycol, ultrasonically dispersing for 1 hour, stirring for 6 hours by a stirrer, then transferring into a reaction kettle to react for 8 hours at 120 ℃, cooling, centrifuging, washing, and drying for 12 hours at 70 ℃ to obtain the LiNi_{1/ 3}Co_1/3-0.05Mn_1/3Al_0.05O₂/GR-3wt% material.

The LiNi prepared in example_1/3Co_1/3-0.05Mn_1/3Al_0.05O₂And LiNi_1/3Co_1/3-0.05Mn_1/3Al_0.05O₂The Raman spectrum of/GR-3 wt% is shown in FIG. 2. As can be seen from FIG. 2, LiNi was produced_1/3Co_1/3-0.05Mn_1/3Al_0.05The O positive electrode material does not have a graphene peak, but LiNi compounded with graphene_1/3Co_1/3-0.05Mn_1/3Al_0.05O₂The Raman diagram of/GR-3 wt% material shows graphene peak, which is probably that graphene is compounded in LiNi_1/3Co_1/3-0.05Mn_1/3Al_0.05O positive electrode materialThe surface of the material.

The obtained LiNi_1/3Co_1/3-0.05Mn_1/3Al_0.05O₂GR-3wt% with acetylene black and polyvinylidene fluoride (PVDF) at 8: 1: 1, rolling into a film with the thickness of 120 mu m, and performing vacuum drying at 120 ℃ for 10 hours to obtain the anode of the experimental half cell; a battery was assembled using 1mol/L LiPF 6/Ethylene Carbonate (EC) -dimethyl carbonate (DMC) (EC to DMC volume ratio 1: 1) electrolyte, and a metal lithium sheet as the negative electrode in a dry argon-filled glove box. LiNi prepared in this example_1/3Co_1/3-0.05Mn_1/3Al_0.05O₂The button cell with/GR-3 wt% as the positive electrode and the lithium sheet as the negative electrode is charged at constant current-constant voltage under 0.1C multiplying power within the voltage range of 2.5-4.3V, the first discharge specific capacity is 163mAh/g when the battery is discharged at constant current under 0.1C multiplying power, but the capacity is only 158mAh/g after 30 cycles.

Claims (9)

1. The graphene composite ternary cathode material for the lithium ion battery is characterized in that an aluminum element is put into a nickel-cobalt-manganese-lithium oxide crystal lattice to replace Co on partial positions³⁺Then, mixing aluminum-doped nickel-cobalt-manganese-lithium oxide with graphene, and preparing the mixture by a hydrothermal method;

the preparation method of the graphene composite ternary cathode material for the lithium ion battery comprises the following steps:

(1) dissolving potassium permanganate in certain deionized water, dropwise adding concentrated hydrochloric acid in a certain molar ratio, stirring for 15 minutes, placing the mixture into a reaction kettle for hydrothermal reaction, cooling, centrifuging, washing and drying to obtain brown manganese dioxide, and then calcining for 6 hours at 350 ℃ in a muffle furnace to obtain a solid product A;

(2) mixing the solid product A obtained in the step (1) with a nickel source, a cobalt source, an aluminum source and a lithium salt according to a certain molar ratio, adding the mixture into a mixed solution of water and absolute ethyl alcohol, ultrasonically dispersing for 0.5-1 hour, stirring and evaporating to dryness to obtain a solid mixture B, grinding the solid mixture B, putting the ground mixture B into a crucible, and calcining to obtain the aluminum-doped nickel-cobalt-manganese-lithium oxide LiNixChol-x-y-zMnyAlzO₂A positive electrode material;

(3) mixing graphene and the LiNixChol-x-y-zMnyAlzO prepared in the step (2)₂The anode material is placed in water/glycol solution with the concentration of 0.01-0.02mol/L, ultrasonically dispersed for 0.5-2 hours, stirred, placed in a reaction kettle for hydrothermal reaction, cooled and centrifugally washed to obtain LiNixChol-x-y-zMnyAlzO₂A graphene composite positive electrode material.

2. The preparation method of the graphene composite ternary cathode material for the lithium ion battery as claimed in claim 1, wherein the hydrothermal reaction temperature in the step (1) is 140-.

3. The preparation method of the lithium ion battery graphene composite ternary cathode material according to claim 1, wherein in the step (2), the cobalt source is one or more of cobalt nitrate, cobalt acetate and cobalt chloride; the nickel source is one or more of nickel nitrate, nickel acetate and nickel chloride; the aluminum source is one or more of aluminum nitrate and aluminum chloride; the lithium salt is one or more of lithium carbonate, lithium acetate and lithium nitrate.

4. The method for preparing the graphene composite ternary cathode material for the lithium ion battery according to claim 1, wherein in the step (2), the lithium salt, the cobalt source, the nickel source, the aluminum source and the brown manganese dioxide are dissolved in a mixed solution of water and absolute ethyl alcohol according to a certain molar ratio, and the concentration is kept to be 0.1-0.15 mol/L.

5. The preparation method of the lithium ion battery graphene composite ternary cathode material according to claim 1, wherein the volume ratio of water to absolute ethyl alcohol in the mixed solution of water and absolute ethyl alcohol in the step (2) is 1: 0-10.

6. The preparation method of the graphene composite ternary cathode material for the lithium ion battery according to claim 1, wherein the evaporation temperature in the step (2) is 60-75 ℃, the calcination process comprises heating to 400-.

7. The preparation method of the graphene composite ternary cathode material for the lithium ion battery according to claim 1, wherein the aluminum-doped nickel-cobalt-manganese-lithium oxide LiNixClx-y-zMnyAlzO 2 cathode material obtained in the step (2) is characterized in that x is 0< x <0.5, y is 0< 0.5, and z is 0< z < 0.05.

8. The preparation method of the lithium ion battery graphene composite ternary cathode material according to claim 1, wherein the amount of graphene used in the step (3) accounts for 1-10% of the mass of LiNixCol-x-y-zMnyAlzO2, and the volume ratio of water to ethylene glycol in the mixed solution of water and ethylene glycol is 1-2: 1.

9. the preparation method of the lithium ion battery graphene composite ternary cathode material as claimed in claim 1, wherein the hydrothermal reaction in the step (3) is carried out at a temperature of 120-140 ℃, the reaction time is 10-12 hours, the drying temperature is 70-80 ℃, and the drying time is 8-12 hours.

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