Positive electrode active material, method for producing the same, battery, and use thereof

Abstract

The application relates to the field of positive electrode active materials, in particular to a positive electrode active material and a preparation method thereof, a battery and application, and aims to solve the problems of short cycle life, poor rate performance and low thermal safety. 3+ The nickel-cobalt-manganese ternary material is first doped with Al, then coated with ZrO2, and finally compounded with carbon nanotubes; the preparation method not only retains the high energy density advantage of the high-nickel ternary material, but also solves the core pain points of short cycle life, poor rate performance and low thermal safety. 3+ The Al doping stabilizes the body phase structure and can inhibit volume expansion; the ZrO2 coating can block the corrosion of electrolyte and reduce transition metal dissolution; the carbon nanotube compounding can construct a conductive network and improve electron conduction. Under the triple synergistic effect, the cycle life of the material is prolonged, the rate performance is optimized, and the thermal safety and interface stability are significantly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of positive electrode active materials, in particular to a positive electrode active material, a preparation method thereof, a battery and application. BACKGROUND

[0002] With the rapid development of new energy industry, lithium ion batteries are widely used in electric vehicles, energy storage devices and other fields due to their high energy density, long cycle life and other advantages. As a core component of lithium ion batteries, the performance of positive electrode active material directly determines the key indicators such as capacity, cycle life and safety of the battery.

[0003] The ternary material positive electrode active material is a widely used high-performance lithium ion battery positive electrode material. Although the energy density of the ternary material is high, its cycle life, rate performance and thermal safety need to be further improved.

[0004] Therefore, it is of great practical significance to develop a positive electrode active material with high energy density, good cycle stability and high safety. SUMMARY

[0005] In order to overcome the above technical problems, the purpose of the present application is to provide a positive electrode active material, a preparation method thereof, a battery and application.

[0006] The purpose of the present application can be achieved by the following technical solutions:

[0007] In a first aspect, the present application provides a preparation method of a positive electrode active material, comprising the following steps:

[0008] Step a1: weigh Ni(NO3)2·6H2O, Co(NO3)2·6H2O, Mn(NO3)2·4H2O, Al(NO3)3·9H2O and deionized water, stir until completely dissolved to obtain a mixed salt solution;

[0009] Step a2: add deionized water to a 500mL reaction kettle, pass nitrogen gas at a flow rate of 1L / min for 30min, then heat to 55-65℃ under the condition of stirring rate of 600-700r / min, use a constant flow pump to pump the mixed salt solution at a flow rate of 5mL / min, NaOH solution at a flow rate of 2mL / min and NH3·H2O solution at a flow rate of 1mL / min into the reaction kettle at the same time, then react for 6-7h, continue to stir for 2h to mature the particles, after the reaction is completed, centrifuge the suspension at 7000-8000r / min for 10-12min, collect the precipitate, wash the precipitate with deionized water for 5-7 times until the pH of the filtrate is 7, finally wash once with anhydrous ethanol, then place the precipitate in a vacuum drying oven, dry at 55-60℃ for 12-14h, grind to obtain Al3+ doped precursor;

[0010] Step a3: ZrOCl2-ethanol solution, polyvinylpyrrolidone were added into a three-necked flask equipped with a stirrer, a thermometer and a gas inlet tube, and ultrasonic dispersion was carried out for 30 min under the condition of a power of 300 W to obtain a ZrO2 sol;

[0011] Step a4: Al 3+ The doped precursor and the ZrO2 sol were added into a three-necked flask equipped with a stirrer, a thermometer and a gas inlet tube, and nitrogen was introduced for protection. Stirring was carried out at a temperature of 55-60°C and a stirring rate of 400-500 r / min for 2-3 h, followed by centrifugation at 7000-8000 r / min for 10-12 min, and then the sample was placed in a vacuum drying box and dried at a temperature of 55-60°C for 6-7 h. The dried powder was pre-fired in a muffle furnace under an air atmosphere at 250-300°C for 2-3 h to obtain ZrO2-coated Al 3+ doped precursor;

[0012] Step a5: Carbon nanotubes and concentrated nitric acid were added into a three-necked flask equipped with a stirrer, a thermometer and a reflux condenser, and refluxing was carried out at a temperature of 75-80°C and a stirring rate of 400-500 r / min for 6-7 h, followed by centrifugation at 7000-8000 r / min for 10-12 min, washing with deionized water until the pH of the filtrate was 6, and then placing the sample in a vacuum drying box and drying at a temperature of 55-60°C for 12-14 h. Anhydrous ethanol was then added, and ultrasonic dispersion was carried out for 30 min under the condition of a power of 500 W to form a carbon nanotube suspension;

[0013] Step a6: The ZrO2-coated Al 3+ The doped precursor and the carbon nanotube suspension were added into a three-necked flask equipped with a stirrer, a thermometer and a reflux condenser, and stirring was carried out in a 30°C constant-temperature water bath at a stirring rate of 300-400 r / min for 1-2 h, and ultrasonic dispersion was carried out for 30-40 min under the condition of a power of 500 W. The sample was then placed in a vacuum drying box and dried at a temperature of 55-60°C for 6-8 h. After drying, the sample was ground for 10-20 min and passed through a 200-mesh sieve to obtain a carbon nanotube-coated precursor composite;

[0014] Step a7: carbon nanotube-coated precursor composite, anhydrous ethanol were added into a three-necked flask, and stirred and dispersed at a stirring rate of 200-300 r / min for 10-12 min, and silane coupling agent KH550 was added, and constant temperature water bath reaction was carried out at a temperature of 50-55℃ and a stirring rate of 270-300 r / min for 1.5-2 h, after the reaction was completed, centrifugation was carried out at a rotation speed of 6000-7000 r / min for 10-12 min, and the solid product was collected and placed in a vacuum drying box for drying at a temperature of 50-55℃ for 6-7 h, to obtain a modified carbon nanotube-coated precursor composite;

[0015] Step a8: LiOH·H2O, the modified carbon nanotube-coated precursor composite and anhydrous ethanol were weighed and added into a ball milling jar, the ball-to-material ratio was 5:1, the rotation speed of the planetary ball mill was set to 300 r / min, and ball milling was carried out for 4 h, and after ball milling, drying was carried out in a vacuum drying box at 60℃ for 8-9 h, and after drying, the powder was sieved through a 200 mesh sieve, and then calcination was carried out, under an oxygen atmosphere with a flow rate of 1.5 L / min, at a rate of 5℃ / min to 500℃ for 5 h, and then at a rate of 3℃ / min to 880℃ for 12 h, after the heat preservation was completed, the heating was turned off, and after natural cooling, the product was ground in a jade mortar for 20 min and sieved through a 300 mesh sieve, to obtain a positive electrode active material.

[0016] As a preferred embodiment of the present application, the amount ratio of Ni(NO3)2·6H2O, Co(NO3)2·6H2O, Mn(NO3)2·4H2O, Al(NO3)3·9H2O and deionized water in step a1 is 93-100 g:11-13 g:9-10 g:1.5-1.7 g:200-250 mL.

[0017] As a preferred embodiment of the present application, the amount ratio of deionized water, mixed salt solution, NaOH solution and NH3·H2O solution in step a2 is 100-120 mL:160-220 mL:100-120 mL:50-60 mL.

[0018] As a preferred embodiment of the present application, the concentration of the NaOH solution in step a2 is 5 mol / L; and the concentration of the NH3·H2O solution is 20 wt%.

[0019] As a preferred embodiment of the present application, the amount ratio of ZrOCl2-ethanol solution and polyvinylpyrrolidone in step a3 is 100-120 mL:0.01-0.03 g.

[0020] As a preferred embodiment of the present application, the CAS number of the polyvinylpyrrolidone in step a3 is 9003-39-8.

[0021] As a preferred embodiment of the present application, the ZrOCl2-ethanol solution in step a3 is ZrOCl2·8H2O, anhydrous ethanol is added into a beaker in a ratio of 0.6g:100mL, and the solution obtained by stirring at room temperature for 60-70min.

[0022] As a preferred embodiment of the present application, the Al 3+ The amount ratio of the doped precursor, ZrO2 sol is 9-10g:90-100mL.

[0023] As a preferred embodiment of the present application, the amount ratio of the carbon nanotube, concentrated nitric acid and anhydrous ethanol in step a5 is 5-6g:100-120mL:100-120mL.

[0024] As a preferred embodiment of the present application, the diameter of the carbon nanotube in step a5 is 10-20nm, and the aspect ratio is 50-100.

[0025] As a preferred embodiment of the present application, the concentration of the concentrated nitric acid in step a5 is 65wt%.

[0026] As a preferred embodiment of the present application, the ZrO2-coated Al 3+ The amount ratio of the doped precursor, ZrO2 sol is 9-10g:90-100mL.

[0027] As a preferred embodiment of the present application, the amount ratio of the carbon nanotube, concentrated nitric acid and anhydrous ethanol in step a5 is 5-6g:100-120mL:100-120mL.

[0028] As a preferred embodiment of the present application, the amount ratio of the carbon nanotube, concentrated nitric acid and anhydrous ethanol in step a5 is 5-6g:100-120mL:100-120mL.

[0029] In a second aspect, the present application provides a positive electrode active material, which is prepared according to the method for preparing a positive electrode active material.

[0030] In a third aspect, the present application provides a battery, which comprises a positive electrode, a negative electrode, a separator and an electrolyte, wherein the positive electrode is prepared according to the following process:

[0031] The positive active material, acetylene black, polyvinylidene fluoride and N-methyl pyrrolidone in the second aspect are stirred by a magnetic stirrer at a rotating speed of 300-500 r / min for 4-6 h, the prepared slurry is uniformly coated on the pretreated aluminum foil current collector by a doctor blade method, the thickness of the coating is uniform, the coated aluminum foil is transferred to a vacuum drying oven, and is dried at 80 DEG C for 12 h, after drying, the electrode sheet is rolled by a rolling machine, the rolling pressure is controlled at 5-10 MPa, and the compaction density of the electrode sheet is 2.2-2.3 g / cm 3 , and finally the positive electrode is obtained.

[0032] The specific preparation process of the battery is as follows:

[0033] Lithium sheet is used as the negative electrode, Celgard2400 polypropylene microporous membrane is used as the separator, the electrolyte is 1 mol / L LiPF6 (EC:DEC=1:1, v / v), the positive electrode, the negative electrode, the separator and the electrolyte are assembled in an argon glove box with a water and oxygen content of less than 1 ppm, and after assembly, the battery is placed for 24 h to obtain the battery.

[0034] As a preferred embodiment of the application, the use ratio of the positive active material, acetylene black, polyvinylidene fluoride and N-methyl pyrrolidone is 85-102 g:4-6 g:5-6 g:90-95 mL.

[0035] In a fourth aspect, the application provides the application of the positive active material in the positive electrode material of the battery.

[0036] The application has the following beneficial effects:

[0037] The positive active material, the preparation method thereof, the battery and the application thereof of the application are prepared by first doping the nickel-cobalt-manganese ternary material with Al 3+ , then coating the Al-doped material with ZrO2, and finally compounding the Al-doped and ZrO2-coated material with carbon nanotubes; the preparation method not only retains the high energy density advantage of the high-nickel ternary material, but also solves the core pain points of short cycle life, poor rate performance and low thermal safety. 3+ The Al 3+ doping stabilizes the body phase structure and inhibits volume expansion; the ZrO2 coating blocks the corrosion of the electrolyte and reduces the dissolution of transition metals; and the carbon nanotube compounding constructs a conductive network and improves electronic conduction.

[0038] The Al 3+ doping reduces the expansion / contraction of the body phase structure, indirectly reduces the risk of cracks in the ZrO2 coating layer caused by particle deformation, and makes the protective effect of the coating layer more durable; the ZrO2 coating isolates the direct reaction between the ternary material and the electrolyte, prolonging the service life of the conductive network; and the high conductivity of the carbon nanotube offsets the Al3+ The negative effects of doping and ZrO2 coating insulation layer, achieve the balance of "stability-conductivity".

[0039] Al 3+ Ion radius and Ni 3+ Close, can replace part of the transition metal site into the layered lattice of ternary materials, due to the Al-O bond energy is significantly higher than the Ni-O bond, can stabilize the oxygen layer arrangement, inhibit the release of lattice oxygen in the charge and discharge process, at the same time, Al 3+ Doping can reduce the lithium nickel mixed degree, reduce the blockage of lithium ion transport channel; and reduce the fracture caused by internal stress of particles.

[0040] ZrO2 has excellent chemical stability and good resistance to acid and alkali corrosion, and has good compatibility with the surface of ternary materials. By uniform coating, a dense physical barrier can be formed, which can block the direct contact of electrolyte, especially HF produced by LiPF6 hydrolysis, with the surface of ternary materials, reducing the dissolution of transition metals (Ni, Co, Mn). In addition, the high temperature resistance of ZrO2 is much better than that of traditional Al2O3 coating layer, which can still maintain integrity under high temperature cycle or overcharge conditions, avoiding direct corrosion of electrolyte to exposed material surface.

[0041] The carboxyl group introduced on the surface of the acid-treated carbon nanotube can enhance the interfacial bonding force with the precursor particles; by ultrasonic-stirring compounding, the carbon nanotubes are uniformly distributed on the surface and gap of the particles, forming a three-dimensional conductive network. Since the conductivity of carbon nanotubes is much higher than that of ternary materials itself, the electronic transmission resistance can be significantly reduced. At the same time, the flexible structure of carbon nanotubes can buffer the volume change in the charge and discharge process, reduce the failure of conductive contact between particles, and ensure the rapid transmission of electrons under high rate.

[0042] The alkoxy group of silane coupling agent KH550 can undergo condensation reaction with the hydroxyl group on the surface of ZrO2 coating layer, forming stable Si-O-Zr covalent bond, and its amino group can form hydrogen bond or acid-base action with the carboxyl group on the surface of carbon nanotube, significantly improving the interfacial bonding force of carbon nanotube, ZrO2 coating layer and precursor three; the silane molecules form a dense organic-inorganic hybrid layer on the surface of the composite, which can reduce the corrosion of HF in the electrolyte to the positive electrode material and reduce the dissolution rate of transition metal ions. DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0044] Example 1:

[0045] The present embodiment is a preparation method of a positive active material, a battery and an application, comprising the following steps:

[0046] Step s1: weigh 93 g of Ni(NO3)2·6H2O, 11 g of Co(NO3)2·6H2O, 9 g of Mn(NO3)2·4H2O, 1.5 g of Al(NO3)3·9H2O, and 200 mL of deionized water, stir until completely dissolved to obtain a mixed salt solution;

[0047] Step s2: add 100 mL of deionized water into a 500 mL reaction kettle, pass nitrogen gas at a flow rate of 1 L / min for 30 min, then heat to 55°C under the condition of a stirring rate of 600 r / min, use a constant flow pump to pump 160 mL of the mixed salt solution at a flow rate of 5 mL / min, 100 mL of NaOH solution at a flow rate of 2 mL / min, and 50 mL of NH3·H2O solution at a flow rate of 1 mL / min into the reaction kettle at the same time, then react for 6 h, continue to stir for 2 h to mature the particles, after the reaction is completed, centrifuge the suspension at 7000 r / min for 10 min, collect the precipitate, wash the precipitate with deionized water for 5 times until the pH of the filtrate is 7, finally wash once with anhydrous ethanol, then place the precipitate in a vacuum drying box, dry at 55°C for 12 h, grind to obtain Al 3+ doped precursor;

[0048] Step s3: add 100 mL of ZrOCl2-ethanol solution and 0.01 g of polyvinylpyrrolidone into a three-necked flask equipped with a stirrer, a thermometer and a gas inlet tube, ultrasonically disperse for 30 min under the condition of a power of 300 W to obtain ZrO2 sol;

[0049] Step s4: add 9 g of Al 3+ doped precursor, 90 mL of ZrO2 sol into a three-necked flask equipped with a stirrer, a thermometer and a gas inlet tube, protect with nitrogen gas, stir at a temperature of 55°C and a stirring rate of 400 r / min for 2 h, then centrifuge at 7000 r / min for 10 min, then place in a vacuum drying box, dry at a temperature of 55°C for 6 h, pre-burn the dried powder in a muffle furnace under air atmosphere at 250°C for 2 h to obtain ZrO2-coated Al 3+ doped precursor;

[0050] Step s5: 5 g of carbon nanotubes, 100 mL of concentrated nitric acid were added to a three-necked flask equipped with a stirrer, a thermometer and a reflux condenser, and refluxed at a temperature of 75 DEG C and a stirring rate of 400 r / min for 6 h, and then centrifuged at a speed of 7000 r / min for 10 min, washed with deionized water until the pH of the filtrate was 6, and then placed in a vacuum drying oven and dried at a temperature of 55 DEG C for 12 h, and then 100 mL of anhydrous ethanol was added and ultrasonically dispersed at a power of 500 W for 30 min to form a carbon nanotube suspension;

[0051] Step s6: 8 g of ZrO2-coated Al 3+ The doped precursor and 20 mL of the carbon nanotube suspension were added to a three-necked flask equipped with a stirrer, a thermometer and a reflux condenser, placed in a constant temperature water bath at 30 DEG C, stirred at a stirring rate of 300 r / min for 1 h, ultrasonically dispersed at a power of 500 W for 30 min, and then placed in a vacuum drying oven and dried at a temperature of 55 DEG C for 6 h, and then ground for 10 min and sieved through a 200-mesh sieve to obtain a carbon nanotube-coated precursor composite;

[0052] Step s7: 5 g of the carbon nanotube-coated precursor composite and 100 mL of anhydrous ethanol were added to a three-necked flask and stirred and dispersed at a stirring rate of 200 r / min for 10 min, 0.10 g of silane coupling agent KH550 was added, and a constant temperature water bath reaction was carried out at a temperature of 50 DEG C and a stirring rate of 270 r / min for 1.5 h, after the reaction was completed, centrifuged at a speed of 6000 r / min for 10 min, the solid product was collected, placed in a vacuum drying oven and dried at a temperature of 50 DEG C for 6 h to obtain a modified carbon nanotube-coated precursor composite;

[0053] Step s8: 9 g of LiOH H2O and 8 g of the modified carbon nanotube-coated precursor composite were weighed into a ball mill jar, the ball-to-material ratio was 5:1, the planetary ball mill was set to rotate at a speed of 300 r / min, and ball milling was carried out for 4 h, after ball milling, the mixture was dried in a vacuum drying oven at 60 DEG C for 8 h, after drying, the powder was sieved through a 200-mesh sieve, and then calcined in an oxygen atmosphere at a flow rate of 1.5 L / min, the temperature was increased to 500 DEG C at a rate of 5 DEG C / min and held for 5 h, and then increased to 880 DEG C at a rate of 3 DEG C / min and held for 12 h, after the holding was completed, the heating was turned off, and after natural cooling, the mixture was ground in an agate mortar for 20 min and sieved through a 300-mesh sieve to obtain a positive electrode active material;

[0054] Step s9: 85 g of the positive electrode active material, 4 g of acetylene black, 5 g of polyvinylidene fluoride, and 90 mL of N-methylpyrrolidone were stirred by a magnetic stirrer at a speed of 300 r / min for 4 h, the prepared slurry was uniformly coated on the pretreated aluminum foil current collector by a doctor blade method, the thickness of the coating was uniform, the coated aluminum foil was transferred to a vacuum drying oven and dried at 80℃ for 12 h, after drying, the electrode sheet was rolled by a roller press, the rolling pressure was controlled at 5 MPa, and the compaction density of the electrode sheet was 2.2 g / cm 3 to obtain a positive electrode;

[0055] Step s10: a lithium sheet was used as a negative electrode, a Celgard 2400 polypropylene microporous membrane was used as a separator, and a 1 mol / L LiPF6 (EC:DEC=1:1, v / v) electrolyte was used, the positive electrode, negative electrode, separator, and electrolyte were assembled in an argon glove box with a water and oxygen content of less than 1 ppm, and after assembly, the battery was allowed to stand for 24 h to obtain a battery.

[0056] Example 2:

[0057] The present embodiment relates to a preparation method of a positive electrode active material, a battery, and an application, comprising the following steps:

[0058] Step s1: 96 g of Ni(NO3)2·6H2O, 12 g of Co(NO3)2·6H2O, 9.5 g of Mn(NO3)2·4H2O, 1.6 g of Al(NO3)3·9H2O, and 220 mL of deionized water were weighed and stirred until completely dissolved to obtain a mixed salt solution;

[0059] Step s2: 110 mL of deionized water was added to a 500 mL reaction kettle, nitrogen gas was introduced at a flow rate of 1 L / min for 30 min, then the temperature was increased to 60℃ under stirring at a speed of 650 r / min, 200 mL of the mixed salt solution at a flow rate of 5 mL / min, 110 mL of NaOH solution at a flow rate of 2 mL / min, and 55 mL of NH3·H2O solution at a flow rate of 1 mL / min were pumped into the reaction kettle simultaneously by a constant flow pump, then the reaction was continued for 6 h, and the particles were matured by stirring for another 2 h, after the reaction was completed, the suspension was centrifuged at 7500 r / min for 11 min, the precipitate was washed with deionized water for 6 times until the pH of the filtrate was 7, and finally the precipitate was washed once with anhydrous ethanol, then the precipitate was placed in a vacuum drying oven and dried at 57℃ for 12-14 h, and after grinding, Al 3+ doped precursor;

[0060] Step s3: 110 mL ZrOCl2-ethanol solution, 0.02 g polyvinylpyrrolidone were added into a three-neck flask equipped with a stirrer, a thermometer and a gas inlet tube, and ultrasonic dispersion was performed for 30 min under the condition of a power of 300 W to obtain a ZrO2 sol;

[0061] Step s4: 9.5 g Al 3+ The doped precursor and 95 mL ZrO2 sol were added into a three-neck flask equipped with a stirrer, a thermometer and a gas inlet tube, and stirring was performed under the condition of a temperature of 57 ℃ and a stirring rate of 450 r / min for 2 h, followed by centrifugation at 7500 r / min for 11 min, and then the sample was placed in a vacuum drying box and dried at a temperature of 57 ℃ for 6 h. The dried powder was pre-fired in a muffle furnace under an air atmosphere at 270 ℃ for 2.5 h to obtain ZrO2-coated Al 3 + The doped precursor;

[0062] Step s5: 5.5 g carbon nanotubes and 110 mL concentrated nitric acid were added into a three-neck flask equipped with a stirrer, a thermometer and a reflux condenser, and refluxing was performed under the condition of a temperature of 77 ℃ and a stirring rate of 450 r / min for 6.5 h, followed by centrifugation at 7500 r / min for 11 min, washing with deionized water until the pH of the filtrate was 6, and then the sample was placed in a vacuum drying box and dried at a temperature of 57 ℃ for 13 h. Then 110 mL anhydrous ethanol was added, and ultrasonic dispersion was performed for 30 min under the condition of a power of 500 W to form a carbon nanotube suspension;

[0063] Step s6: 9 g ZrO2-coated Al 3+ The doped precursor and 23 mL carbon nanotube suspension were added into a three-neck flask equipped with a stirrer, a thermometer and a reflux condenser, and stirring was performed in a 30 ℃ constant-temperature water bath under the condition of a stirring rate of 3500 r / min for 1.5 h, and ultrasonic dispersion was performed for 35 min under the condition of a power of 500 W. Then the sample was placed in a vacuum drying box and dried at a temperature of 57 ℃ for 7 h. After drying, the sample was ground for 15 min and passed through a 200-mesh sieve to obtain a carbon nanotube-coated precursor composite;

[0064] Step s7: 5.5 g of carbon nanotube-coated precursor composite and 110 mL of anhydrous ethanol were added to a three-necked flask, and stirred at a stirring rate of 250 r / min for 11 min, and then 0.11 g of silane coupling agent KH550 was added, and a constant temperature water bath reaction was carried out at a temperature of 53℃ and a stirring rate of 280 r / min for 1.7 h, and after the reaction was completed, centrifugation was carried out at a rotation speed of 6900 r / min for 11 min, and the solid product was collected and placed in a vacuum drying box for drying at a temperature of 53℃ for 6.5 h, to obtain a modified carbon nanotube-coated precursor composite;

[0065] Step s8: 9.5 g of LiOH·H2O and 9 g of the modified carbon nanotube-coated precursor composite were added to a ball milling tank, and the ball-to-material ratio was 5:1, the rotation speed of the planetary ball mill was set to 300 r / min, and ball milling was carried out for 4 h, and then the ball-milled product was dried in a vacuum drying box at 60℃ for 8 h, and after drying, the powder was sieved through a 200-mesh sieve, and then calcination was carried out, and the oxygen flow rate was 1.5 L / min, the temperature was increased to 500℃ at a rate of 5℃ / min and maintained for 5 h, and then the temperature was increased to 880℃ at a rate of 3℃ / min and maintained for 12 h, and after the heat preservation was completed, the heating was turned off, and the product was naturally cooled and ground in a jade mortar for 20 min, and then sieved through a 300-mesh sieve, to obtain a positive electrode active material;

[0066] Step s9: 93 g of the positive electrode active material, 5 g of acetylene black, 5.5 g of polyvinylidene fluoride, and 93 mL of N-methylpyrrolidone were stirred by a magnetic stirrer at a rotation speed of 400 r / min for 5 h, and then the prepared slurry was uniformly coated on a pretreated aluminum foil current collector by a doctor blade method, to ensure that the coating thickness was uniform and consistent, and then the coated aluminum foil was transferred to a vacuum drying box and dried at 80℃ for 12 h, and after drying was completed, a rolling machine was used to roll the electrode sheet, and the rolling pressure was controlled at 7 MPa, so that the compaction density of the electrode sheet reached 2.2 g / cm 3 , and finally a positive electrode was obtained.

[0067] Step s10: A lithium sheet was used as a negative electrode, a Celgard 2400 polypropylene microporous membrane was used as a separator, and an electrolyte was 1 mol / L of LiPF6 (EC:DEC=1:1, v / v), and then the positive electrode, the negative electrode, the separator, and the electrolyte were assembled into a battery in an argon glove box with a water and oxygen content of less than 1 ppm, and after assembly was completed, the battery was allowed to stand for 24 h, and a battery was obtained.

[0068] Example 3:

[0069] The present embodiment is a preparation method of a positive electrode active material, a battery, and an application, which comprises the following steps:

[0070] Step s1: take 100 g of Ni(NO3)2·6H2O, 13 g of Co(NO3)2·6H2O, 10 g of Mn(NO3)2·4H2O, 1.7 g of Al(NO3)3·9H2O, 250 mL of deionized water, stir until completely dissolved, and obtain a mixed salt solution;

[0071] Step s2: add 120 mL of deionized water to a 500 mL reaction kettle, pass nitrogen gas at a flow rate of 1 L / min for 30 min, then heat to 65°C under stirring at a rate of 700 r / min, use a constant flow pump to pump 220 mL of mixed salt solution at a flow rate of 5 mL / min, 120 mL of NaOH solution at a flow rate of 2 mL / min, and 60 mL of NH3·H2O solution at a flow rate of 1 mL / min into the reaction kettle simultaneously, then react for 7 h, continue stirring for 2 h to mature the particles, after the reaction is completed, centrifuge the suspension at 8000 r / min for 12 min, collect the precipitate, wash the precipitate with deionized water for 7 times until the pH of the filtrate is 7, finally wash once with anhydrous ethanol, then place the precipitate in a vacuum drying oven, dry at 60°C for 14 h, grind to obtain Al 3+ doped precursor;

[0072] Step s3: add 120 mL of ZrOCl2-ethanol solution and 0.03 g of polyvinylpyrrolidone to a three-necked flask equipped with a stirrer, a thermometer, and a gas inlet tube, ultrasonically disperse for 30 min under the condition of a power of 300 W, and obtain ZrO2 sol;

[0073] Step s4: add 10 g of Al 3+ doped precursor, 100 mL of ZrO2 sol to a three-necked flask equipped with a stirrer, a thermometer, and a gas inlet tube, protect with nitrogen gas, stir at a temperature of 60°C and a stirring rate of 500 r / min for 3 h, then centrifuge at 8000 r / min for 12 min, then place in a vacuum drying oven, dry at a temperature of 60°C for 7 h, pre-burn the dried powder in a muffle furnace under air atmosphere at 300°C for 3 h, and obtain ZrO2-coated Al 3+ doped precursor;

[0074] Step s5: add 6 g of carbon nanotubes and 120 mL of concentrated nitric acid to a three-necked flask equipped with a stirrer, a thermometer, and a reflux condenser, reflux at a temperature of 80°C and a stirring rate of 500 r / min for 7 h, then centrifuge at 8000 r / min for 12 min, wash with deionized water until the pH of the filtrate is 6, then place in a vacuum drying oven, dry at a temperature of 60°C for 14 h, then add 120 mL of anhydrous ethanol, ultrasonically disperse for 30 min under a power of 500 W, and form a carbon nanotube suspension;

[0075] Step s6: 10 g of ZrO2-coated Al 3+ The doped precursor, 26 mL of the carbon nanotube suspension, was added to a three-necked flask equipped with a stirrer, a thermometer, and a reflux condenser, placed in a 30°C constant-temperature water bath, stirred at a stirring rate of 400 r / min for 2 h, ultrasonically dispersed at a power of 500 W for 40 min, and then placed in a vacuum drying box and dried at a temperature of 60°C for 8 h. After drying, the mixture was ground for 20 min and passed through a 200-mesh sieve to obtain a carbon nanotube-coated precursor composite;

[0076] Step s7: 6 g of the carbon nanotube-coated precursor composite and 120 mL of anhydrous ethanol were added to a three-necked flask, stirred and dispersed at a stirring rate of 300 r / min for 12 min, 0.12 g of silane coupling agent KH550 was added, and a constant-temperature water bath reaction was performed at a temperature of 55°C and a stirring rate of 300 r / min for 2 h. After the reaction was completed, centrifugation was performed at a rotation speed of 7000 r / min for 12 min, the solid product was collected, placed in a vacuum drying box, and dried at a temperature of 55°C for 7 h to obtain a modified carbon nanotube-coated precursor composite;

[0077] Step s8: 10 g of LiOH·H2O and 10 g of the modified carbon nanotube-coated precursor composite were weighed into a ball milling tank, the ball-to-material ratio was 5:1, the rotation speed of the planetary ball mill was set to 300 r / min, and ball milling was performed for 4 h. After ball milling, the mixture was dried in a vacuum drying box at 60°C for 9 h. After drying, the powder was passed through a 200-mesh sieve, and then calcination was performed. In an oxygen atmosphere at a flow rate of 1.5 L / min, the temperature was increased to 500°C at a rate of 5°C / min and maintained for 5 h, and then increased to 880°C at a rate of 3°C / min and maintained for 12 h. After the heat was turned off, the mixture was naturally cooled, ground in an agate mortar for 20 min, and passed through a 300-mesh sieve to obtain a positive electrode active material;

[0078] Step s9: 102 g of the positive electrode active material, 6 g of acetylene black, 6 g of polyvinylidene fluoride, and 95 mL of N-methylpyrrolidone were stirred by a magnetic stirrer at a rotation speed of 500 r / min for 6 h. The prepared slurry was uniformly coated on a pretreated aluminum foil current collector by a doctor blade method to ensure uniform thickness of the coating. The coated aluminum foil was transferred to a vacuum drying box and dried at 80°C for 12 h. After drying, the electrode sheet was roll-pressed using a roll press at a pressure of 10 MPa to achieve a compaction density of 2.3 g / cm 3 , and finally obtained a positive electrode;

[0079] Step s10: using lithium sheet as negative electrode, Celgard 2400 polypropylene microporous membrane as separator, and 1 mol / L LiPF6 (EC:DEC=1:1, v / v) as electrolyte, the positive electrode, negative electrode, separator and electrolyte were assembled in an argon glove box with water and oxygen content less than 1 ppm, and then the battery was obtained after standing for 24 h.

[0080] Comparative Example 1

[0081] The present comparative example is a preparation method of a positive electrode active material, a battery and an application, comprising the following steps:

[0082] Step s1: weigh 93 g of Ni(NO3)2·6H2O, 11 g of Co(NO3)2·6H2O, 9 g of Mn(NO3)2·4H2O and 200 mL of deionized water, and stir until completely dissolved to obtain a mixed salt solution;

[0083] Step s2: 100 mL of deionized water was added to a 500 mL reaction kettle, and nitrogen gas with a flow rate of 1 L / min was introduced for 30 min, then the temperature was raised to 55°C under the condition of stirring rate of 600 r / min, and 160 mL of mixed salt solution with flow rate of 5 mL / min, 100 mL of NaOH solution with flow rate of 2 mL / min and 50 mL of NH3·H2O solution with flow rate of 1 mL / min were pumped into the reaction kettle at the same time using a constant flow pump, then the reaction was continued for 6 h, and then the particles were aged by stirring for 2 h, after the reaction was completed, the suspension was centrifuged at 7000 r / min for 10 min, the precipitate was collected, washed with deionized water for 5 times until the pH of the filtrate was 7, and finally washed with anhydrous ethanol once, then the precipitate was placed in a vacuum drying oven and dried at 55°C for 12 h, and after grinding, the precursor was obtained;

[0084] Step s3: weigh 9 g of LiOH·H2O, 10 g of the precursor and 100 mL of anhydrous ethanol into a ball mill tank, the ball-to-material ratio is 5:1, the planetary ball mill speed is set to 300 r / min, ball milling for 4 h, then placed in a vacuum drying oven at 60°C for 8 h, after drying, the powder is passed through a 200 mesh sieve, then calcined in an oxygen atmosphere with a flow rate of 1.5 L / min, at a rate of 5°C / min to 500°C for 5 h, then at a rate of 3°C / min to 880°C for 12 h, after the heat preservation is completed, the heating is turned off, and after natural cooling, the material is ground in a jade mortar for 20 min, and then passed through a 300 mesh sieve to obtain the positive electrode active material;

[0085] Step s4: 85 g of the positive electrode active material, 4 g of acetylene black, 5 g of polyvinylidene fluoride, and 90 mL of N-methylpyrrolidone were stirred by a magnetic stirrer at a speed of 300 r / min for 4 h, the prepared slurry was uniformly coated on the pretreated aluminum foil current collector by a doctor blade method, the thickness of the coating was uniform, the coated aluminum foil was transferred to a vacuum drying oven and dried at 80 °C for 12 h, after drying, the electrode sheet was rolled by a roller press, the rolling pressure was controlled at 5 MPa, and the compaction density of the electrode sheet was 2.2 g / cm 3 to obtain a positive electrode;

[0086] Step s5: a lithium sheet was used as a negative electrode, a Celgard 2400 polypropylene microporous membrane was used as a separator, and an electrolyte was 1 mol / L of LiPF6 (EC:DEC=1:1, v / v), the positive electrode, the negative electrode, the separator, and the electrolyte were assembled in an argon glove box with a water and oxygen content of less than 1 ppm, and the battery was obtained after standing for 24 h after assembly.

[0087] Comparative Example 2

[0088] The present comparative example is a preparation method of a positive electrode active material, a battery, and an application, comprising the following steps:

[0089] Step s1: 93 g of Ni(NO3)2·6H2O, 11 g of Co(NO3)2·6H2O, 9 g of Mn(NO3)2·4H2O, 1.5 g of Al(NO3)3·9H2O, and 200 mL of deionized water were weighed and stirred until completely dissolved to obtain a mixed salt solution;

[0090] Step s2: 100 mL of deionized water was added to a 500 mL reaction kettle, nitrogen gas was introduced at a flow rate of 1 L / min for 30 min, then the temperature was increased to 55 °C under stirring at a speed of 600 r / min, 160 mL of the mixed salt solution at a flow rate of 5 mL / min, 100 mL of NaOH solution at a flow rate of 2 mL / min, and 50 mL of NH3·H2O solution at a flow rate of 1 mL / min were pumped into the reaction kettle simultaneously by a constant flow pump, then the reaction was continued for 6 h, and the particles were matured by stirring for another 2 h, after the reaction was completed, the suspension was centrifuged at 7000 r / min for 10 min, the precipitate was washed with deionized water for 5 times until the pH of the filtrate was 7, and finally the precipitate was washed once with anhydrous ethanol, then the precipitate was placed in a vacuum drying oven and dried at 55 °C for 12 h, and after grinding, Al 3+ doped precursor;

[0091] Step s3: 9 g of LiOH·H2O, 9 g of Al 3+The doped precursor, 100 mL of anhydrous ethanol, was added to a ball milling tank, the ball-to-material ratio was 5:1, the planetary ball mill was set to rotate at 300 r / min, and the ball milling was performed for 4 h. After ball milling, the mixture was dried in a vacuum drying oven at 60℃ for 8 h. After drying, the powder was sieved through a 200-mesh sieve. Then, calcination was performed in an oxygen atmosphere at a flow rate of 1.5 L / min, at a rate of 5℃ / min to 500℃ for 5 h, and then at a rate of 3℃ / min to 880℃ for 12 h. After the heat preservation was completed, the heating was turned off, and the mixture was naturally cooled for 20 min using a jade mortar and then sieved through a 300-mesh sieve to obtain the positive electrode active material;

[0092] Step s4: 85 g of the positive electrode active material, 4 g of acetylene black, 5 g of polyvinylidene fluoride, and 90 mL of N-methylpyrrolidone were stirred at a speed of 300 r / min using a magnetic stirrer for 4 h. The prepared slurry was uniformly coated on the pretreated aluminum foil current collector using a doctor blade method, and the coating thickness was ensured to be uniform. The coated aluminum foil was transferred to a vacuum drying oven and dried at 80℃ for 12 h. After drying, the electrode sheet was subjected to roll pressing using a roll press machine at a pressure of 5 MPa, so that the electrode sheet had a compacted density of 2.2 g / cm 3 , and finally the positive electrode was obtained.

[0093] Step s5: The positive electrode, a lithium sheet as the negative electrode, a Celgard 2400 polypropylene microporous membrane as the separator, and an electrolyte of 1 mol / L LiPF6 (EC:DEC=1:1, v / v) were assembled into a battery in an argon glove box with a water and oxygen content of less than 1 ppm. After assembly, the battery was allowed to stand for 24 h to obtain the battery.

[0094] Comparative Example 3:

[0095] The present comparative example is a preparation method of a positive electrode active material, a battery, and an application, which comprises the following steps:

[0096] Step s1: 93 g of Ni(NO3)2·6H2O, 11 g of Co(NO3)2·6H2O, 9 g of Mn(NO3)2·4H2O, 1.5 g of Al(NO3)3·9H2O, and 200 mL of deionized water were weighed and stirred until completely dissolved to obtain a mixed salt solution.

[0097] Step s2: 100 mL of deionized water was added to a 500 mL reaction kettle, nitrogen was introduced at a flow rate of 1 L / min for 30 min, then the temperature was raised to 55°C under the condition of stirring rate of 600 r / min, 160 mL of mixed salt solution at a flow rate of 5 mL / min, 100 mL of NaOH solution at a flow rate of 2 mL / min, and 50 mL of NH3·H2O solution at a flow rate of 1 mL / min were pumped into the reaction kettle simultaneously by using a constant flow pump, then the reaction was carried out for 6 h, and the particles were aged by continuing stirring for 2 h, after the reaction was completed, the suspension was centrifuged at 7000 r / min for 10 min, the precipitate was collected, washed with deionized water for 5 times until the pH of the filtrate was 7, and finally washed once with anhydrous ethanol, then the precipitate was placed in a vacuum drying box and dried at 55°C for 12 h, after grinding, Al 3+ doped precursor;

[0098] Step s3: 100 mL of ZrOCl2-ethanol solution and 0.01 g of polyvinylpyrrolidone were added to a three-necked flask equipped with a stirrer, a thermometer, and a gas inlet tube, and ultrasonic dispersion was carried out under the condition of power of 300 W for 30 min to obtain ZrO2 sol;

[0099] Step s4: 9 g of Al 3+ doped precursor and 90 mL of ZrO2 sol were added to a three-necked flask equipped with a stirrer, a thermometer, and a gas inlet tube, and stirring was carried out under the condition of temperature of 55°C and stirring rate of 400 r / min for 2 h, then centrifugation was carried out at 7000 r / min for 10 min, then it was placed in a vacuum drying box and dried at a temperature of 55°C for 6 h, after drying, the powder was pre-fired in a muffle furnace under air atmosphere at 250°C for 2 h to obtain ZrO2-coated Al 3+ doped precursor;

[0100] Step s5: 9 g of LiOH·H2O and 8 g of ZrO2-coated Al 3+ doped precursor and 100 mL of anhydrous ethanol were added to a ball milling jar, the ball-to-material ratio was 5:1, the rotation speed of the planetary ball mill was set to 300 r / min, ball milling was carried out for 4 h, after ball milling, it was dried in a vacuum drying box at 60°C for 8 h, after drying, the powder was sieved through a 200 mesh sieve, then calcination was carried out, under the condition of oxygen atmosphere at a flow rate of 1.5 L / min, the temperature was raised to 500°C at a rate of 5°C / min and maintained for 5 h, then the temperature was raised to 880°C at a rate of 3°C / min and maintained for 12 h, after the maintenance was completed, the heating was turned off, and after natural cooling, it was ground in an agate mortar for 20 min and sieved through a 300 mesh sieve to obtain a positive electrode active material;

[0101] Step s6: 85 g of the positive electrode active material, 4 g of acetylene black, 5 g of polyvinylidene fluoride, and 90 mL of N-methylpyrrolidone were stirred by a magnetic stirrer at a speed of 300 r / min for 4 h, the prepared slurry was uniformly coated on the pretreated aluminum foil current collector by a doctor blade method, the coating thickness was uniform, the coated aluminum foil was transferred to a vacuum drying oven and dried at 80°C for 12 h, after drying, the electrode sheet was rolled by a roller press, the rolling pressure was controlled at 5 MPa, and the compaction density of the electrode sheet was 2.2 g / cm 3 to obtain a positive electrode;

[0102] Step s7: lithium was used as the negative electrode, Celgard 2400 polypropylene microporous membrane was used as the separator, and the electrolyte was 1 mol / L LiPF6 (EC:DEC=1:1, v / v), the positive electrode, the negative electrode, the separator, and the electrolyte were assembled in an argon glove box with a water and oxygen content of less than 1 ppm, and after assembly, the battery was placed for 24 h to obtain the battery.

[0103] Performance test:

[0104] The positive electrode active material, the preparation method thereof, the battery, and the application of the positive electrode active material of Examples 1-3 and Comparative Examples 1-3 were tested for the capacity retention rate after 500 cycles at a 1C charge-discharge rate, the thermal decomposition onset temperature was tested, and the discharge capacity at 0.2C and 5C rates was tested.

[0105] The test results are shown in the following table:

[0106] Table 1: Test results of Examples 1-3 and Comparative Examples 1-3

[0107]

[0108] Referring to Table 1, according to the comparison between Examples 1-3, it can be seen that the cycle life of the positive electrode active material is significantly prolonged, the rate performance is greatly optimized, and the thermal safety is significantly improved.

[0109] Referring to Table 1, according to the comparison between Example 1 and Comparative Example 1, it can be seen that the Al 3+ Doping can stabilize the bulk structure and inhibit volume expansion; ZrO2 coating can block electrolyte corrosion and reduce transition metal dissolution; carbon nanotube composite can construct a conductive network to improve electron conduction; after ZrO2 coating and carbon nanotube composite, the Al 3+ The performance of the doped ternary material is better than that of the ordinary ternary material.

[0110] Referring to Table 1, according to the comparison between Example 1 and Comparative Example 2, it can be seen that the Al 3+The doping can stabilize the bulk structure and inhibit volume expansion; the ZrO2 coating can block the corrosion of electrolyte and reduce the dissolution of transition metal; the carbon nanotube composite can construct a conductive network and improve electronic conduction; the carbon nanotube composite ZrO2 coated Al 3+ The doped ternary material is better than the ZrO2 coated Al 3+ The doped ternary material has better performance.

[0111] According to the comparison between Example 1 and Comparative Example 3, it can be seen that the Al 3+ The doping can stabilize the bulk structure and inhibit volume expansion; the ZrO2 coating can block the corrosion of electrolyte and reduce the dissolution of transition metal; the carbon nanotube composite can construct a conductive network and improve electronic conduction; the carbon nanotube composite ZrO2 coated Al 3+ The doped ternary material is better than the ZrO2 coated Al 3+ The doped ternary material has better performance.

[0112] In the description of the present specification, the description referring to the terms "one embodiment", "example", "specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0113] The above is only an example and description of the present application, and those skilled in the art can make various modifications or supplements or use similar ways to replace the described specific embodiments, as long as they do not deviate from the invention or exceed the scope defined in the present application, which shall belong to the protection scope of the present application.

Claims

1. A method for producing a positive electrode active material, characterized by, The method comprises the following steps: Step a1: Ni(NO3)2·6H2O, Co(NO3)2·6H2O, Mn(NO3)2·4H2O, Al(NO3)3·9H2O and deionized water are stirred to obtain a mixed salt solution; Step a2: deionized water was added into the reaction kettle, heated, and mixed salt solution, NaOH solution and NH3·H2O solution were pumped into the reaction kettle simultaneously with constant flow pump, after reaction, continue stirring, centrifugation, washing, drying, grinding, and then Al 3+ doped precursor; Step a3: ZrOCl2-ethanol solution is ultrasonically dispersed to obtain ZrO2 sol; Step a4: Al 3+ The doped precursor, Zr02sol stirred reaction, centrifugation, drying, pre-burning, to get Zr02coated Al 3 + Doped precursor; Step a5: carbon nanotubes and concentrated nitric acid are added into a three-necked flask for reflux reaction, centrifuged, washed and dried, and then anhydrous ethanol is added for ultrasonic dispersion to form a carbon nanotube suspension; Step a6: ZrO2-coated Al 3+ The doped precursor, carbon nanotube suspension is stirred in water bath, ultrasonic dispersed, dried, ground to obtain carbon nanotube-coated precursor composite; Step a7: the carbon nanotube-coated precursor composite and anhydrous ethanol are added into a three-necked flask for stirring and dispersion, silane coupling agent KH550 is added, constant temperature water bath reaction is carried out, centrifuged and dried to obtain a modified carbon nanotube-coated precursor composite; Step a8: LiOH·H2O, the modified carbon nanotube-coated precursor composite and anhydrous ethanol are ball milled, dried, sieved, calcined, ground after cooling to obtain a positive electrode active material.

2. The method for producing a positive electrode active material according to claim 1, characterized by, The amount ratio of the Ni (NO3) 2·6H2O, Co (NO3) 2·6H2O, Mn (NO3) 2·4H2O, Al (NO3) 3·9H2O and deionized water in step a1 is 93-100g:11-13g:9-10g:1.5-1.7g:200-250mL; the amount ratio of the deionized water, mixed salt solution, NaOH solution and NH3·H2O solution in step a2 is 100-120mL:160-220mL:100-120mL:50-60mL; the amount ratio of the ZrOCl2-ethanol solution and polyvinylpyrrolidone in step a3 is 100-120mL:0.01-0.03g; the amount ratio of the Al 3+ The amount ratio of the doped precursor and ZrO2 sol in step a4 is 9-10g:90-100mL; the amount ratio of the carbon nanotube, concentrated nitric acid and anhydrous ethanol in step a5 is 5-6g:100-120mL:100-120mL; the amount ratio of the ZrO2 coated Al 3+ The amount ratio of the doped precursor and ZrO2 sol in step a4 is 9-10g:90-100mL; the amount ratio of the carbon nanotube, concentrated nitric acid and anhydrous ethanol in step a5 is 5-6g:100-120mL:100-120mL; the amount ratio of the ZrO2 coated Al The amount ratio of the doped precursor and ZrO2 sol in step a4 is 9-10g:90-100mL; the amount ratio of the carbon nanotube, concentrated nitric acid and anhydrous ethanol in step a5 is 5-6g:100-120mL:100-120mL; the amount ratio of the ZrO2 coated Al 3. The method for producing a positive electrode active material according to claim 1, characterized by, The concentration of the NaOH solution in step a2 is 5 mol / L; and the concentration of the NH3·H2O solution is 20 wt%.

4. The method for producing a positive electrode active material according to claim 1, characterized by, The ZrOCl2-ethanol solution in step a3 is obtained by adding ZrOCl2·8H2O and anhydrous ethanol into a beaker in a ratio of 0.6 g:100 mL, stirring for 60-70 min at room temperature.

5. The method of producing a positive electrode active material according to claim 1, characterized by, The diameter of the carbon nanotubes in step a5 is 10-20 nm, and the length-diameter ratio is 50-100.

6. The method of producing a positive electrode active material according to claim 1, characterized by, The concentration of the concentrated nitric acid in step a5 is 65 wt%.

7. A positive electrode active material, characterized in that, The positive electrode active material is prepared according to the preparation method of the positive electrode active material in any one of claims 1-6.

8. A battery, characterized by The battery comprises a positive electrode, a negative electrode, a separator and an electrolyte, and the specific preparation process of the positive electrode is as follows: The positive electrode active material, acetylene black, polyvinylidene fluoride and N-methyl pyrrolidone are stirred, the prepared slurry is uniformly coated on a pretreated aluminum foil current collector by using a doctor blade method, dried, and then the electrode sheet is subjected to roll pressing treatment by using a roll press to obtain the positive electrode. The specific preparation process of the battery is as follows: Lithium sheet is used as the negative electrode, polypropylene microporous membrane is used as the separator, and the electrolyte is 1 mol / L LiPF6 (EC:DEC=1:1, v / v), the positive electrode, the negative electrode, the separator and the electrolyte are assembled in an argon glove box with a water and oxygen content of less than 1 ppm, and the battery is obtained after standing for 24 h.

9. A battery according to claim 8, wherein The dosage ratio of the positive electrode active material, acetylene black, polyvinylidene fluoride and N-methyl pyrrolidone is 85-102 g:4-6 g:5-6 g:90-95 mL.

10. The positive electrode active material prepared by the preparation method of the positive electrode active material in any one of claims 1-6 is applied to a battery positive electrode material.

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