A phosphotungstic acid-coated nickel-rich ternary lithium-ion battery cathode material and a preparation method thereof

Abstract

The application discloses a phosphotungstic acid coated nickel-rich ternary lithium ion battery positive electrode material, which comprises a nickel-rich ternary lithium ion battery positive electrode material and a surface coating material phosphotungstic acid, and the nickel-rich ternary lithium ion battery positive electrode material is composed of a nickel-cobalt-manganese hydroxide precursor and a lithium source. The application further discloses a preparation method of the phosphotungstic acid coated nickel-rich ternary lithium ion battery positive electrode material, wherein the nickel-cobalt-manganese oxide precursor and the lithium source are mixed and continuously grinded, the nickel-rich ternary lithium ion battery positive electrode material is obtained by fully mixing and sintering, the nickel-rich ternary lithium ion battery positive electrode material is mixed with the phosphotungstic acid and continuously grinded, and the phosphotungstic acid coated nickel-rich ternary lithium ion battery positive electrode material is prepared by fully mixing and sintering. The phosphotungstic acid coated nickel-rich ternary lithium ion battery positive electrode material has the advantages of low cost, high stability, low heat production rate and low heat production, the prepared battery has high specific capacity, and the battery life and safety are effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium ion batteries, in particular to a phosphotungstic acid coated nickel-rich ternary lithium ion battery cathode material and a preparation method thereof. BACKGROUND

[0002] With the growing demand for clean energy and sustainable transportation worldwide, the market for electric vehicles is rapidly rising. Traditional lithium ion battery cathode materials use lithium cobaltate, but due to the scarcity and high cost of cobalt resources, its development in large-scale applications is limited. Nickel-rich ternary lithium ion battery cathode materials have gradually become a research hotspot and development direction for lithium ion battery cathode materials due to their high specific capacity, relatively low cost, and good safety.

[0003] With the increase of nickel content, the stability of nickel-rich ternary lithium ion battery cathode material decreases, and structural reconstruction, particle rupture, transition metal ion dissolution, and positive electrolyte interface film damage easily occur during long-term cycling. The thermal stability of oxide cathodes in a high delithiation state is extremely poor, and they can easily decompose to produce oxygen at high temperatures, leading to the severe oxidation of the electrolyte on the surface of the cathode, releasing a large amount of heat and generating a large amount of gas, which can induce serious fires and explosions in the battery.

[0004] The above problems need to be solved, so it is necessary to develop a phosphotungstic acid coated nickel-rich ternary lithium ion battery cathode material and a preparation method thereof. SUMMARY

[0005] In view of the deficiencies in the prior art, one object of the present application is to provide a phosphotungstic acid coated nickel-rich ternary lithium ion battery cathode material. First, a nickel-cobalt-manganese hydroxide precursor ( ) and a lithium source are mixed to prepare a nickel-rich ternary lithium ion battery cathode material, and then the nickel-rich ternary lithium ion battery cathode material is sintered with phosphotungstic acid in a tube furnace to obtain a phosphotungstic acid coated nickel-rich ternary lithium ion battery cathode material with high specific capacity, low heat generation rate, and high safety.

[0006] To achieve the above technical problems, the present application provides the following technical solutions:

[0007] A phosphotungstic acid coated nickel-rich ternary lithium ion battery cathode material, comprising a nickel-rich ternary lithium ion battery cathode material and a material phosphotungstic acid ( ) coated on the surface of the nickel-rich ternary lithium ion battery cathode material. The nickel-rich ternary lithium ion battery cathode material is composed of a nickel-cobalt-manganese hydroxide precursor ( ) and a lithium source.

[0008] Preferably, the mass ratio of each component of the nickel-rich ternary lithium ion battery cathode material is as follows: nickel-cobalt-manganese hydroxide precursor ( The lithium source ratio is 1:1.05.

[0009] Preferably, the phosphotungstic acid ( The amount of ) is 0.5% to 2%.

[0010] Preferably, the lithium source is lithium hydroxide (…). ) and lithium carbonate ( One of them.

[0011] Preferably, the nickel-cobalt-manganese hydroxide precursor ( The particle size is selected from one or more of 25μm, 50μm, 100μm, 200μm, and 400μm.

[0012] Another objective of this invention is a method for preparing the above-mentioned phosphotungstic acid-coated nickel-rich ternary lithium-ion battery cathode material, which specifically includes the following steps:

[0013] Step 1: Weigh out the nickel-cobalt-manganese hydroxide precursor according to the mass percentage ( 10 parts of lithium source and 10.5 parts of lithium source;

[0014] Step 2: Weigh the nickel-cobalt-manganese hydroxide precursor ( After mixing with the lithium source, continue grinding for 30 minutes;

[0015] Step 3: Place the thoroughly mixed material into a tube furnace and sinter at 500 ℃ for 5 h, with an oxygen flow rate of 50-150 ml / min;

[0016] Step 4: Remove the cooled powder and grind it for 5 minutes;

[0017] Step 5: Place the ground material into a tube furnace and sinter at 680-760 ℃ for 15 h to obtain the nickel-rich ternary lithium-ion battery cathode material.

[0018] Step 6: Weigh out 0.5% to 2% of the mass of the synthesized nickel-rich ternary lithium-ion battery cathode material, containing phosphotungstic acid (PSA). );

[0019] Step 7: Weigh out the phosphotungstic acid (PHOTO) After mixing with the weighed nickel-rich ternary lithium-ion battery cathode material, continue grinding for 30 min.

[0020] Step 8: Place the thoroughly mixed material into a tube furnace and sinter at 300 °C for 7 h. Then, slowly cool it down to room temperature at a certain rate to obtain the phosphotungstic acid-coated nickel-rich ternary lithium-ion battery cathode material.

[0021] Preferably, the sintering method in the fifth and eighth steps is a tube furnace with an oxygen atmosphere.

[0022] Preferably, the grinding method in the second and fourth steps is one or more of ball milling and manual grinding.

[0023] The beneficial effects of the phosphotungstic acid-coated nickel-rich ternary lithium-ion battery cathode material of the present invention are as follows:

[0024] The phosphotungstic acid-coated nickel-rich ternary lithium-ion battery cathode material of this invention significantly improves the half-motor discharge capacity, exhibits good charge-discharge stability, and effectively extends battery life. The phosphotungstic acid-coated nickel-rich ternary lithium-ion battery cathode material of this invention has low cost, significantly improved quality stability, a markedly reduced heat generation rate and heat generation, and a significantly delayed exothermic peak appearance time, thus achieving excellent electrochemical performance and good thermal safety performance in lithium-ion batteries. Attached Figure Description

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0026] In the picture: Figure 1 The graphs show the specific capacity and cycle stability of the positive electrode half-cells prepared with the materials of Examples 1, 2, 3, and Comparative Example 1 in this invention.

[0027] Figure 2 Comparison of thermogravimetric analysis curves of the cathode materials in Examples 1, 2, 3, and Comparative Example 1 of this invention;

[0028] Figure 3 This is a comparison chart of the thermal analysis DSC curves of the cathode materials in Examples 1, 2, 3, and Comparative Example 1 of this invention. Detailed Implementation

[0029] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0030] This invention provides a phosphotungstic acid-coated nickel-rich ternary lithium-ion battery cathode material, comprising the nickel-rich ternary lithium-ion battery cathode material and the phosphotungstic acid coating material on its surface (… The cathode material for nickel-rich ternary lithium-ion batteries consists of nickel-cobalt-manganese hydroxide precursors (…). Composed of lithium and lithium source;

[0031] Preferably, the mass ratio of each component in the nickel-rich ternary lithium-ion battery cathode material is: nickel hydroxide, cobalt manganese precursor (… The lithium source ratio is 1:1.05.

[0032] Preferably, the phosphotungstic acid (H3PW12O40) accounts for 0.5% to 2% of the mass of the nickel-rich ternary lithium ion battery cathode material.

[0033] Preferably, the lithium source is selected from one of lithium hydroxide (LiOH) and lithium carbonate (Li2CO3).

[0034] Preferably, the particle size of the nickel-cobalt-manganese hydroxide precursor (NixCoyMnz(OH)2) is selected from one or more of 25 μm, 50 μm, 100 μm, 200 μm, and 400 μm.

[0035] The application also provides a preparation method of a phosphotungstic acid-coated nickel-rich ternary lithium ion battery cathode material, which specifically comprises the following steps:

[0036] First step: 10 parts of nickel-cobalt-manganese hydroxide precursor (NixCoyMnz(OH)2) and 10.5 parts of lithium source are weighed according to the mass percentage;

[0037] Second step: the weighed nickel-cobalt-manganese hydroxide precursor (NixCoyMnz(OH)2) and lithium source are mixed and continuously ground for 30 min;

[0038] Third step: the well-mixed material is placed into a tube furnace and sintered at 500 ℃ for 5 h, and the oxygen flow rate is 50-150 ml / min;

[0039] Fourth step: the cooled powder is taken out and ground for 5 min;

[0040] Fifth step: the ground material is placed into a tube furnace and sintered at 680-760 ℃ for 15 h, thereby obtaining a nickel-rich ternary lithium ion battery cathode material;

[0041] Sixth step: phosphotungstic acid (H3PW12O40) accounting for 0.5% to 2% of the mass of the synthesized nickel-rich ternary lithium ion battery cathode material is weighed;

[0042] Seventh step: the weighed phosphotungstic acid (H3PW12O40) is mixed with the synthesized nickel-rich ternary lithium ion battery cathode material and continuously ground for 30 min, thereby obtaining a mixed material;

[0043] Eighth step: the well-mixed material is placed into a tube furnace and sintered at 300 ℃ for 7 h, and then slowly cooled to room temperature at a certain rate, thereby obtaining the phosphotungstic acid-coated nickel-rich ternary lithium ion battery cathode material.

[0044] Example 1:

[0045] First step: 10 parts of nickel-cobalt-manganese hydroxide precursor (NixCoyMnz(OH)2) and 10.5 parts of lithium source are weighed according to the mass percentage;​​​​​​​​ ) 10 parts and lithium source 10.5 parts;

[0046] Second step: the weighed nickel cobalt manganese hydroxide precursor (Ni0.5Co0.2Mn0.3)(OH)2 ) and lithium source were mixed and grinded for 30 min to obtain the mixed material.

[0047] Third step: the mixed material was put into a tube furnace and sintered at 500℃ for 5h, with oxygen flow rate of 50-150 ml / min;

[0048] Fourth step: the cooled powder was taken out and grinded for 5 min;

[0049] Fifth step: the grinded material was put into a tube furnace and sintered at 680-760℃ for 15h to obtain the nickel-rich ternary lithium ion battery cathode material.

[0050] Sixth step: phosphotungstic acid (H3PW12O40) accounting for 0.5% of the mass of the synthesized nickel-rich ternary lithium ion battery cathode material was weighed;

[0051] Seventh step: the weighed phosphotungstic acid (H3PW12O40) was mixed with the synthesized nickel-rich ternary lithium ion battery cathode material and grinded for 30 min.

[0052] Eighth step: the mixed material was put into a tube furnace and sintered at 300℃ for 7h, and then slowly cooled to room temperature at a certain rate to obtain the phosphotungstic acid coated nickel-rich ternary lithium ion battery cathode material.

[0053] Example 2:

[0054] First step: nickel cobalt manganese hydroxide precursor (Ni0.5Co0.2Mn0.3)(OH)2 ) 10 parts and lithium source 10.5 parts were weighed according to mass percentage;

[0055] Second step: the weighed nickel cobalt manganese hydroxide precursor (Ni0.5Co0.2Mn0.3)(OH)2 ) and lithium source were mixed and grinded for 30 min to obtain the mixed material.

[0056] Third step: the mixed material was put into a tube furnace and sintered at 500℃ for 5h, with oxygen flow rate of 50-150 ml / min;

[0057] Fourth step: the cooled powder was taken out and grinded for 5 min;

[0058] Fifth step: the grinded material was put into a tube furnace and sintered at 680-760℃ for 15h to obtain the nickel-rich ternary lithium ion battery cathode material;

[0059] Sixth step: phosphotungstic acid (H3PW12O40) accounting for 1.0% of the mass of the synthesized nickel-rich ternary lithium ion battery cathode material was weighed; );​​

[0060] Step 7: The weighed phosphotungstic acid (PTA) was mixed with the synthesized nickel-rich ternary lithium ion battery cathode material and continuously ground for 30 min;

[0061] Step 8: The well-mixed material was placed in a tube furnace and sintered at 300 ℃ for 7 h, and then slowly cooled to room temperature at a certain rate, to obtain the phosphotungstic acid-coated nickel-rich ternary lithium ion battery cathode material.

[0062] Example 3:

[0063] Step 1: The nickel-cobalt-manganese hydroxide precursor (NCMH) was weighed according to the mass percentage of 10 parts and the lithium source was weighed according to the mass percentage of 10.5 parts;

[0064] Step 2: The weighed nickel-cobalt-manganese hydroxide precursor (NCMH) and lithium source were mixed and continuously ground for 30 min to obtain a mixed material;

[0065] Step 3: The well-mixed material was placed in a tube furnace and sintered at 500 ℃ for 5 h, with an oxygen flow rate of 50-150 ml / min;

[0066] Step 4: The cooled powder was taken out and ground for 5 min;

[0067] Step 5: The ground material was placed in a tube furnace and sintered at 680-760 ℃ for 15 h, to obtain the nickel-rich ternary lithium ion battery cathode material.

[0068] Step 6: The phosphotungstic acid (PTA) was weighed according to 2.0% of the mass of the synthesized nickel-rich ternary lithium ion battery cathode material;

[0069] Step 7: The weighed phosphotungstic acid (PTA) was mixed with the synthesized nickel-rich ternary lithium ion battery cathode material and continuously ground for 30 min;

[0070] Step 8: The well-mixed material was placed in a tube furnace and sintered at 300 ℃ for 7 h, and then slowly cooled to room temperature at a certain rate, to obtain the phosphotungstic acid-coated nickel-rich ternary lithium ion battery cathode material.

[0071] Comparative Example 1:

[0072] Step 1: The nickel-cobalt-manganese hydroxide precursor (NCMH) was weighed according to the mass percentage of 10 parts and the lithium source was weighed according to the mass percentage of 10.5 parts;

[0073] Step 2: The weighed nickel-cobalt-manganese hydroxide precursor (NCMH) and lithium source were mixed and continuously ground for 30 h;

[0074] ​​​​​​​Third step: Put the well-mixed material into a tube furnace and sinter at 500℃ for 5h, with oxygen flow rate of 50-150ml / min;

[0075] Fourth step: Take out the cooled powder and grind for 5min;

[0076] Fifth step: Put the ground material into a tube furnace and sinter at 680-760℃ for 15h to obtain the nickel-rich ternary lithium-ion battery cathode material.

[0077] The materials of Example 1, Example 2, Example 3, Comparative Example 1 were prepared into cathode half-batteries, with the specific steps as follows:

[0078] The cathode material (prepared by Example 1, Example 2, Example 3, Comparative Example 1), conductive agent acetylene black, and binder polyvinylidene fluoride (PVDF) were mixed in a mass ratio of cathode material: acetylene black: polyvinylidene fluoride = 8:1:1. After mixing, N-methyl pyrrolidone (NMP) was added, and the mixture was stirred well to form a uniform cathode slurry, which was then uniformly coated on a 15μm thick aluminum foil. The coated aluminum foil was then dried in a forced air drying oven at 120℃ for 12h to obtain a cathode sheet for standby use.

[0079] The above cathode sheet was used as the cathode, a lithium metal sheet was used as the anode, Celgard 2500 was used as the separator, and a commercial electrolyte was added to assemble a coin-type half-battery in a glove box, with the battery model being CR2032 (lithium-manganese battery button cell model).

[0080] The battery cycle test procedure was as follows:

[0081] The assembled button cell was left to stand at room temperature (25℃) for 12h, and then cycled with a charge-discharge voltage of 2.8-4.3V. The battery was first charged and discharged at a rate of 0.1C for three cycles to fully activate the electrode material, and then cycled at a rate of 0.2C for 50 cycles to evaluate the cycle performance of the battery.

[0082] The test procedure was as follows: 0.1C constant current charging to 4.3V, then constant voltage charging at 4.3V until the current was less than 0.05C, and then discharging at 0.1C to 2.8V. After fully activating the electrode material, the battery was cycled at 0.2C for 50 cycles to evaluate the cycle stability of the battery. The capacity retention rate after 53 cycles was calculated based on the 4th cycle capacity, with the calculation formula being as follows:

[0083] 53rd cycle capacity retention rate = (53rd cycle discharge capacity / 4th cycle discharge capacity) x 100%.

[0084] The obtained data were as follows:Figure 1 as shown;

[0085] Table 1: Charge-discharge test results of Example 1, 2, 3 and Comparative Example 1 in the present application:

[0086]

[0087] The battery thermal gravimetric test process is as follows:

[0088] After the cycle is completed, the battery is disassembled in the glove box, the positive plate is separated out, and the positive plate is cleaned with dimethyl carbonate solvent to remove residual electrolyte and air-dried. The positive material is scraped off from the aluminum sheet, 5 mg of the positive material is weighed into a sample cell, and a thermal gravimetric experiment with a heating range of 30-330°C and a temperature rise rate of 10.0°C / min is performed on a thermal analyzer, and the mass change curve of the positive material during the temperature rise process is recorded. As a comparison, the thermal gravimetric experiment is performed on different positive material samples alone, and the data is as shown in Figure 2 .

[0089] Table 2: Battery thermal gravimetric test results of Example 1, 2, 3 and Comparative Example 1 in the present application

[0090]

[0091] The battery thermal analysis test process is as follows:

[0092] The same pretreatment method as the thermal gravimetric test is used to obtain the positive material, 2 mg of the positive material is weighed into a sample cell, and 1 mg of commercial electrolyte is added dropwise, a differential scanning calorimeter DSC experiment with a heating range of 30-330°C and a temperature rise rate of 10.0°C / min is performed on a thermal analyzer, and the heat production change curve of the positive material during the temperature rise process is recorded. As a comparison, the DSC experiment is performed on different positive material samples alone, and the data is as shown in Figure 3 .

[0093] Table 3: DSC results of Example 1, 2, 3 and Comparative Example 1 in the present application

[0094]

[0095] From the data in Table 1, it can be seen that the initial discharge capacity of the positive electrode half-battery made of the material of Example 1, the positive electrode half-battery made of the material of Example 2, and the positive electrode half-battery made of the material of Example 3 is obviously higher than that of the positive electrode half-battery made of the material of Comparative Example 1, indicating that the discharge capacity of the positive electrode half-battery made of the phosphotungstic acid coated rich-nickel ternary lithium ion battery positive electrode material is significantly improved. Moreover, the initial discharge capacity of the positive electrode half-battery made of the material of Example 1 is obviously higher than that of the positive electrode half-battery made of the material of Example 2 and the positive electrode half-battery made of the material of Example 3, indicating that when the phosphotungstic acid accounts for 0.5% of the mass of the synthesized rich-nickel ternary lithium ion battery positive electrode material, ), the initial capacity of the positive electrode half-battery made of the phosphotungstic acid coated rich-nickel ternary lithium ion battery positive electrode material is the best.

[0096] Comparing Example 1 with Comparative Example 1, compared with the positive electrode half-battery made of the positive electrode material without phosphotungstic acid coating, the specific capacity of the positive electrode half-battery made of the coated positive electrode material increases by 34.58 mA / g in the first cycle, significantly improving the electrochemical performance of the positive electrode half-battery made of the phosphotungstic acid coated rich-nickel ternary lithium ion battery positive electrode material between voltages of 2.8-4.3 V. Comparing Example 2 with Comparative Example 1, the capacity retention rate is improved by 3.81%.

[0097] After 53 cycles of charging / discharging, the capacity retention rates of the positive electrode half-battery made of the material of Example 1, the positive electrode half-battery made of the material of Example 2, and the positive electrode half-battery made of the material of Example 3 are obviously higher than that of Comparative Example 1, indicating that the charging and discharging stability of the positive electrode half-battery made of the phosphotungstic acid coated rich-nickel ternary lithium ion battery positive electrode material is good, and the battery life can be effectively prolonged. Moreover, the capacity retention rate of the positive electrode half-battery made of the material of Example 2 is obviously higher than that of the positive electrode half-battery made of the material of Example 1 and the positive electrode half-battery made of the material of Example 3, indicating that when the phosphotungstic acid accounts for 1% of the mass of the synthesized rich-nickel ternary lithium ion battery positive electrode material, ), the capacity retention rate of the positive electrode half-battery made of the phosphotungstic acid coated rich-nickel ternary lithium ion battery positive electrode material is the best.

[0098] From the data in Table 2, it can be seen that the mass retention rates of the positive electrode material of Example 1, the positive electrode material of Example 2, and the positive electrode material of Example 3 in the same temperature range are obviously higher than that of the positive electrode material of Comparative Example 1, indicating that the mass stability of the phosphotungstic acid coated rich-nickel ternary lithium ion battery positive electrode material is significantly improved, while the positive electrode material of Comparative Example 1 exhibits extremely strong structural instability, which is very unfavorable for maintaining the overall safety of the battery. The mass retention rate of the positive electrode material of Example 1 in the same temperature range is obviously higher than that of the positive electrode material of Example 2 and the positive electrode material of Example 3, indicating that when the phosphotungstic acid accounts for 0.5% of the mass of the synthesized rich-nickel ternary lithium ion battery positive electrode material, When the phosphotungstic acid-coated nickel-rich ternary lithium-ion battery cathode material is used, the quality stability is relatively high.

[0099] Compared with Comparative Example 1, Example 1 showed that the coated cathode material had a thermal weight loss rate reduced by up to 6.27% and an heat release rate reduced by 194.56 J / g compared with the uncoated cathode material.

[0100] As shown in Table 3, the heat generation rate and heat output of the cathode materials in Examples 1, 2, and 3 are significantly lower than those in Comparative Example 1. This indicates that the heat generation rate and heat output of the phosphotungstic acid-coated nickel-rich ternary lithium-ion battery cathode material are significantly reduced, effectively controlling the initial reaction of battery thermal runaway. The heat generation rate and heat output of the cathode material in Example 1 within the same temperature range are significantly lower than those in Examples 2 and 3, indicating that when phosphotungstic acid (0.5% by mass of the synthesized nickel-rich ternary lithium-ion battery cathode material) is used... When the phosphotungstic acid coating is used, the cathode material of the nickel-rich ternary lithium-ion battery has the lowest heat generation rate and heat generation.

[0101] Depend on Figure 3 It can be seen that the exothermic peaks of the cathode materials in Example 1, Example 2, and Example 3 are significantly delayed compared to the cathode material in Comparative Example 1, indicating that the thermal stability of the phosphotungstic acid-coated nickel-rich ternary lithium-ion battery cathode material is significantly improved. The exothermic peak exhibited by the cathode material in Example 1 within the same temperature range is significantly delayed compared to the cathode materials in Example 2 and Example 3, indicating that when 0.5% of the mass of phosphotungstic acid (based on the mass of the synthesized nickel-rich ternary lithium-ion battery cathode material) is used... When the phosphotungstic acid coating is used, the nickel-rich ternary lithium-ion battery cathode material exhibits the best thermal stability.

[0102] In summary, the positive electrode half-cell made from the phosphotungstic acid-coated nickel-rich ternary lithium-ion battery positive electrode material of the present invention exhibits significantly improved discharge capacity, good charge-discharge stability, and effectively extended battery life. Furthermore, the phosphotungstic acid-coated nickel-rich ternary lithium-ion battery positive electrode material of the present invention demonstrates significantly improved quality stability, a markedly reduced heat generation rate and heat generation, and a significantly delayed appearance of the exothermic peak, thus achieving excellent electrochemical performance and good thermal safety performance in lithium-ion batteries.

[0103] Therefore, the phosphotungstic acid coated nickel-rich ternary lithium ion battery positive electrode material can improve the thermal stability of the positive electrode material itself, increase the thermal decomposition reaction temperature of the positive electrode material, delay the thermal runaway speed of the battery, and improve the safety performance of the battery. Phosphotungstic acid can be used as a protective layer to isolate the interface side reaction, not only enhances the lithium ion diffusion capacity of the positive electrode structure, but also inhibits the adverse structure transformation of the material, cooperates with the coating effect of trace phosphorus and tungsten elements, forms a high-quality stable protective layer structure on the surface of the material, protects the structural integrity of the electrode material, inhibits the occurrence of side reactions, improves the cycle performance and discharge performance of the battery,

[0104] The above embodiment is the preferred embodiment of the present application, but the embodiment of the present application is not limited to the above embodiment, any change, modification, substitution, combination, simplification made without departing from the spirit and principles of the present application should be equivalent replacement method, and all are included in the protection scope of the present application.

Claims

1. A method for preparing a phosphotungstic acid-coated nickel-rich ternary lithium-ion battery cathode material, specifically comprising the following steps: First step: take the nickel cobalt manganese hydroxide precursor according to the mass percentage 10 parts and 10.5 parts of lithium source; Second step: Mix the weighed nickel cobalt manganese hydroxide precursor and lithium source and continue to grind for 30 min; Step 3: placing the well-mixed material into a tube furnace and sintering at 500 ℃ for 5 h, with an oxygen flow rate of 50-150 ml / min; Step 4: taking out the cooled powder and grinding for 5 min; Step 5: placing the ground material into a tube furnace and sintering at 680-760 ℃ for 15 h to obtain the nickel-rich ternary lithium-ion battery cathode material; Step 6: Take phosphotungstic acid accounting for 0.5% to 2% of the mass of the synthesized nickel-rich ternary lithium-ion battery cathode material ; Step 7: Weighed phosphotungstic acid and mixed with the synthesized nickel-rich ternary lithium-ion battery cathode material and continuously ground for 30 min; Step 8: placing the well-mixed material into a tube furnace and sintering at 300 ℃ for 7 h, and slowly cooling to room temperature at a certain rate to obtain the phosphotungstic acid-coated nickel-rich ternary lithium-ion battery cathode material.

2. The preparation method of phosphotungstic acid coated nickel-rich ternary lithium-ion battery cathode material according to claim 1, characterized in that: The sintering mode in the fifth step and the eighth step is selected to be a tube furnace in an oxygen atmosphere.

3. The method according to claim 1, wherein the method is characterized by: The grinding mode in the second step and the fourth step is selected to be one or more of a ball mill and manual grinding.

4. The phosphotungstic acid coated nickel-rich ternary lithium-ion battery cathode material prepared according to the preparation method of any one of claims 1-3, characterized in that: The application relates to a nickel-rich ternary lithium ion battery positive electrode material and a material coated on the surface of the nickel-rich ternary lithium ion battery positive electrode material, phosphotungstic acid The nickel-rich ternary lithium ion battery positive electrode material is composed of a nickel-cobalt-manganese hydroxide precursor and a lithium source. 5.The phosphotungstic acid coated nickel-rich ternary lithium-ion battery cathode material of claim 4, wherein: The mass ratio of each component of the nickel-rich ternary lithium ion battery cathode material is: nickel-cobalt-manganese hydroxide precursor : the lithium source is 1:1.

05. 6.The phosphotungstic acid coated nickel-rich ternary lithium-ion battery cathode material of claim 4, wherein: The phosphotungstic acid accounts for 0.5%-2% of the mass of the nickel-rich ternary lithium-ion battery cathode material. 7.The phosphotungstic acid coated nickel-rich ternary lithium-ion battery cathode material of claim 4, wherein: The lithium source is one of lithium hydroxide and lithium carbonate. 8.The phosphotungstic acid coated nickel-rich ternary lithium-ion battery cathode material of claim 4, wherein: The nickel cobalt manganese hydroxide precursor The particle size is selected from one or more of 25 μm, 50 μm, 100 μm, 200 μm, 400 μm.

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