Lithium ion battery positive electrode material, preparation method, positive electrode and battery

Abstract

The invention provides a lithium ion battery positive electrode material, a preparation method, a positive electrode and a battery, and belongs to the field of lithium batteries. The Ni content molar ratio of the lithium ion battery is 80-92%, and the preparation method comprises the following steps: preparing Ni (OH) 2 powder; weighing Ni (OH) 2 powder and soluble salts of Co and Mn according to a preset molar ratio of Ni to Co to Mn; the preparation method comprises the following steps: dissolving soluble salts of Co and Mn in deionized water, and adding Ni (OH) 2 powder; keeping the temperature at 58-62 DEG C, dropwise adding a precipitant and stirring, controlling the pH value at 10, and stirring for 3-4 hours to obtain a precipitate; and cleaning and drying the precipitate to obtain the product. The invention aims to break through the bottleneck in the prior art and solve the core challenges of poor structural stability, short cycle life, difficult process control and the like of the current high-nickel material.

Description

Technical Field

[0001] This invention belongs to the field of lithium battery technology, and specifically relates to a lithium-ion battery cathode material, preparation method, cathode, and battery. Background Technology

[0002] With the rapid development of the commercial lithium-ion battery industry, the development of cathode materials that combine high specific capacity and excellent safety has become a research focus. Among them, high-nickel ternary oxide cathodes, such as LiNi, are... x Co y Mn z O2 (NCM) has attracted much attention due to its high energy density and low cost. In this material system, increasing the nickel content can effectively improve the specific capacity, cobalt can inhibit cation mixing, and manganese plays a role in stabilizing the layered structure.

[0003] Currently, the industrial production of high-nickel cathode materials mainly employs a co-precipitation-solid-phase synthesis method to ensure atomic-level homogeneous mixing of transition metal ions. However, this method has significant limitations: the co-precipitation process is complex and requires specialized equipment (reactors), with stringent requirements for temperature, pH, and stirring rate. Furthermore, with the continuous advancement of ultra-high-nickel cathode materials, further increases in nickel content significantly increase the difficulty of controlling the co-precipitation synthesis process, leading to escalating production costs. In addition, traditional co-precipitation methods rely on ammonia complexing agents to regulate crystallization; even small fluctuations in ammonia concentration, pH gradient, and temperature can result in poor batch consistency, making it difficult to meet the batch stability requirements of large-scale industrialization. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a lithium-ion battery cathode material, a preparation method, a cathode, and a battery. It aims to overcome existing technological bottlenecks and solve the core challenges of current high-nickel materials, such as poor structural stability, short cycle life, and difficulty in process control.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] On one hand, the present invention provides a method for preparing a high-nickel ternary cathode material for lithium-ion batteries, characterized in that the Ni content molar ratio is 80%~92%, comprising the following steps: preparing Ni(OH)2 powder, wherein the Ni(OH)2 powder is composed of particles with a particle size of 10um-20um formed by Ni(OH)2 nanospindle aggregates with a diameter of 60nm-100nm and a length of 400nm-800nm; weighing Ni(OH)2 powder and soluble salts of Co and Mn according to a preset Ni, Co and Mn molar ratio; dissolving the soluble salts of Co and Mn in deionized water, adding Ni(OH)2 powder; maintaining the temperature at 58℃-62℃, adding a precipitant and stirring, controlling the pH value at 10, stirring for 3h-4h to obtain a precipitate; washing and drying the precipitate to obtain the final product.

[0007] Furthermore, the precipitant is an aqueous solution of KOH, and the solubility of the KOH aqueous solution is 30 g / L - 40 g / L.

[0008] Furthermore, the stirring speed is 800 rpm to 1200 rpm.

[0009] Furthermore, the soluble salts of Co and Mn are Co(NO3)2·6H2O and Mn(NO3)2, respectively.

[0010] Furthermore, maintain the temperature at 60°C.

[0011] Furthermore, soluble salts of Co and Mn are dissolved in deionized water, and the amount of deionized water added satisfies the following conditions: the total molar concentration of Co ions and Mn ions is 0.02 mol / L-0.10 mol / L.

[0012] On the other hand, the present invention provides a high-nickel ternary cathode material for lithium-ion batteries, which is prepared by the above-described preparation method.

[0013] On the other hand, the present invention provides a lithium-ion battery cathode, which is prepared using the above-mentioned high-nickel ternary cathode material.

[0014] On the other hand, the present invention provides a lithium-ion battery, wherein the lithium-ion battery uses the above-mentioned high-nickel ternary cathode material to prepare the cathode; or uses the above-mentioned cathode.

[0015] The beneficial effects of the technical solution provided by the embodiments of the present invention include: For Ni content molar ratios of 80%~92%, the increased nickel content significantly increases the difficulty of controlling the co-precipitation synthesis process, leading to higher production costs. Furthermore, existing technologies use ammonia complexing agents to regulate crystallization, which is difficult to control and results in poor consistency between different batches. To solve these problems, the present invention utilizes Ni(OH)₂ powder with specific morphology, combined with subsequent precipitation, avoiding complex precursor nucleation-growth kinetic equilibrium studies. It eliminates the need for pre-nucleation and aging, saving significant time in the co-precipitation process. Secondly, the elimination of ammonia complexing agents also reduces costs and process complexity. Finally, the precursor prepared by this technical solution has a core-shell structure, which itself improves the lifespan and cycle performance of the cathode material, eliminating the need for additional modification treatment. To achieve the surface morphology required by this invention, the morphology of the Ni(OH)₂ particles and the subsequent parameter control during precipitation are crucial. Within the aforementioned temperature, pH, and stirring time range, a small portion of the nickel hydroxide on the surface will dissolve, while cobalt and manganese will completely precipitate as hydroxides. These precipitates exist as particles with a diameter of approximately 40 nm to 60 nm. The sites where the spherical nickel hydroxide dissolves provide attachment sites for the cobalt and manganese precipitation. During stirring, the dissolution of nickel and the precipitation of cobalt and manganese occur simultaneously, representing an ion exchange process. That is, when nickel dissolves from the surface, cobalt and manganese replace the nickel's position. As stirring continues, cobalt and manganese grow at their attachment sites, eventually forming particles with a diameter of approximately 40 nm to 60 nm that adhere to the surface of the spherical nickel hydroxide. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 The image shows the morphology of Ni(OH)2 particles used in the embodiments of the present invention.

[0018] Figure 2 This is a partial enlarged view of the Ni(OH)2 particles used in the embodiments of the present invention;

[0019] Figure 3 This is a SEM image of the ternary cathode material prepared in Example 1 of the present invention;

[0020] Figure 4 This is an elemental distribution diagram of the ternary cathode material prepared in Example 1 of the present invention after sintering;

[0021] Figure 5The image shows the XRD pattern of the ternary cathode material prepared in Example 1 of this invention after sintering.

[0022] Figure 6 This is a graph showing the performance test of the lithium-ion battery prepared in Example 1 of this invention after 200 charge-discharge cycles.

[0023] Figure 7 This is a comparison of the charge and discharge performance of the lithium-ion battery prepared in Example 1 of the present invention with that of commercially available products;

[0024] Figure 8 This is a performance comparison between the lithium-ion battery prepared in Example 1 of the present invention and commercially available products at different discharge rates.

[0025] Figure 9 This is an elemental distribution diagram of the ternary cathode material prepared in Example 2 of the present invention after sintering;

[0026] Figure 10 This is an elemental distribution diagram of the ternary cathode material prepared in Example 3 of the present invention after sintering;

[0027] Figure 11 Here is a SEM image of the ternary cathode material prepared in Comparative Example 1 of this invention;

[0028] Figure 12 The image shows the XRD pattern of the ternary cathode material prepared in Comparative Example 1 of this invention after sintering.

[0029] Figure 13 The graph shows the performance test results of the lithium-ion battery prepared in Comparative Example 1 of this invention after 200 charge-discharge cycles.

[0030] Figure 14 Here is a SEM image of the ternary cathode material prepared in Comparative Example 2 of this invention;

[0031] Figure 15 The image shows the XRD pattern of the ternary cathode material prepared in Comparative Example 2 of this invention after sintering. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] This invention provides a method for preparing a high-nickel ternary cathode material for lithium-ion batteries, wherein the Ni content molar ratio is 80%~92%, comprising the following steps: preparing Ni(OH)2 powder, wherein the Ni(OH)2 powder is composed of particles with a particle size of 10um-20um formed by Ni(OH)2 nanospindle aggregates with a diameter of 60nm-100nm and a length of 400nm-800nm; weighing Ni(OH)2 powder and soluble salts of Co and Mn according to a preset Ni, Co, and Mn molar ratio; dissolving the soluble salts of Co and Mn in deionized water, adding Ni(OH)2 powder; maintaining the temperature at 58℃-62℃, adding a precipitant dropwise and stirring, controlling the pH value at 10, stirring for 3h-4h to obtain a precipitate; washing and drying the precipitate to obtain the final product.

[0034] This invention targets Ni content with a molar ratio of 80%~92%. Increased nickel content significantly increases the difficulty of controlling the co-precipitation synthesis process, leading to higher production costs. Furthermore, existing technologies use ammonia complexing agents to regulate crystallization, which is difficult to control and results in poor batch-to-batch consistency. To address these issues, this invention utilizes Ni(OH)₂ powder with specific morphologies, combined with subsequent precipitation. This avoids complex precursor nucleation-growth kinetics equilibrium studies, eliminating the need for pre-nucleation and aging, thus saving significant time in the co-precipitation process. Secondly, the elimination of ammonia complexing agents reduces costs and process complexity. Finally, the precursor prepared by this method has a core-shell structure, which inherently improves the lifespan and cycle performance of the cathode material, eliminating the need for additional modification. To achieve the surface morphology required by this invention, the morphology of the Ni(OH)₂ particles and the subsequent parameter control during precipitation are crucial. Within the aforementioned temperature, pH, and stirring time range, a small portion of the nickel hydroxide on the surface will dissolve, while cobalt and manganese will completely precipitate as hydroxides. These precipitates exist as particles with a diameter of approximately 40 nm to 60 nm. The sites where the spherical nickel hydroxide dissolves provide attachment sites for the cobalt and manganese precipitation. During stirring, the dissolution of nickel and the precipitation of cobalt and manganese occur simultaneously, representing an ion exchange process. That is, when nickel dissolves from the surface, cobalt and manganese replace the nickel's position. As stirring continues, cobalt and manganese grow at their attachment sites, eventually forming particles with a diameter of approximately 40 nm to 60 nm that adhere to the surface of the spherical nickel hydroxide.

[0035] It should be noted that the above technical parameters are very critical. Only when the above morphology is combined with the sintering in the subsequent cathode preparation can diffusion between ions occur, forming a homogeneous NCM.

[0036] Specifically, such as Figure 1 and Figure 2As shown, the Ni(OH)₂ particles of this application are spherical with a particle size of 10-20 μm, and are composed of Ni(OH)₂ nanospindle fibers with a diameter of 60-100 nm and a length of 400-800 nm. This powder was purchased from Aladdin's nickel hydroxide CAS: 12054-48-7, N104966-100g.

[0037] The precipitate is washed and dried. Specifically, the filtered material is placed in an 80°C forced-air drying oven for at least 24 hours.

[0038] Specifically, the precipitant is an aqueous solution of KOH, with a concentration of 30 g / L - 40 g / L. The concentration of the precipitant is quite important. If the concentration is too high, excessive local cobalt and manganese deposits will occur, resulting in poor uniformity of the material prepared in the same batch while maintaining the same nickel dissolution rate. Conversely, if the concentration is too low, the deposition rate of cobalt and manganese will be lower while maintaining the same nickel dissolution rate, resulting in poor morphology of the prepared high-nickel ternary cathode material.

[0039] The stirring speed is 800 rpm-1200 rpm. The stirring speed affects the particle size of cobalt and manganese deposits on the Ni(OH)2 surface, reducing the problem of poor uniformity within the same batch due to excessively high local concentrations.

[0040] Preferably, in the embodiments of the present invention, the soluble salts of Co and Mn are Co(NO3)2·6H2O and Mn(NO3)2, respectively.

[0041] Preferably, the temperature is maintained at 60°C.

[0042] Preferably, the soluble salts of Co and Mn are dissolved in deionized water, and the amount of deionized water added satisfies the following condition: the total molar concentration of Co ions and Mn ions is 0.02 mol / L-0.10 mol / L. The technical solution of this invention achieves a dynamic equilibrium during the precipitation process, meaning that the dissolution rate of nickel matches the deposition rate of cobalt and manganese, ultimately achieving the technical effect of this application. Therefore, the higher the concentration of cobalt and manganese, the faster their deposition rate, while the dissolution rate of nickel fluctuates little, leading to a mismatch between the dissolution rate of nickel and the deposition rate of cobalt and manganese. This results in excessively large deposition sizes of cobalt and manganese on the surface of Ni(OH)2 particles, even encapsulating the Ni(OH)2 core, which in turn leads to poor performance of the final prepared cathode material. Conversely, a lower concentration results in smaller cobalt and manganese particle sizes, while the amount of Ni dissolved is large, leading to deteriorated surface morphology and low compaction density of the prepared cathode material, thus reducing its performance.

[0043] This invention also provides a high-nickel ternary cathode material for lithium-ion batteries, which is prepared using the above-described preparation method.

[0044] This invention also provides a lithium-ion battery cathode, which is prepared using the aforementioned high-nickel ternary cathode material.

[0045] Specifically, the prepared high-nickel ternary cathode material for lithium-ion batteries is mixed with an excess of 5% lithium source in a mortar and wet-milled with ethanol until dry. It is then placed in a tube furnace and calcined in an oxygen atmosphere. The specific heating regime is as follows: the temperature is increased from room temperature to 500-600℃ at a rate of 3-5℃ / min to prevent incomplete decomposition of moisture, which could easily enter the particles. The temperature is then held at 500-600℃ for 6 hours to ensure complete decomposition of lithium hydroxide. The temperature is then increased to 700-800℃ at a rate of 1-3℃ / min and held at 700-800℃ for 12 hours to ensure sufficient reaction. Finally, the temperature is decreased to 550-650℃ / min at a rate of 2-4℃ / min to reduce internal stress. The furnace is then allowed to cool naturally.

[0046] Preferably, the lithium source is lithium hydroxide.

[0047] For comparison, this invention uses commercially available cathode materials with the same elemental ratios as those used in this application to prepare a cathode, and then measures its performance. Commercially available products were purchased from the Ternary Materials Network: https: / / e.tb.cn / h.SpxvBEyoSndfsLM?tk=USH1fhQgRIN.

[0048] To better illustrate the embodiments of the present invention, the present invention will be further described in detail below through specific examples.

[0049] Example 1

[0050] This invention provides a method for preparing a high-nickel ternary cathode material for lithium-ion batteries, comprising:

[0051] S1. Prepare Ni(OH)2 powder, wherein the Ni(OH)2 powder is composed of particles with a particle size of 10um-20um formed by Ni(OH)2 nanospindles with a diameter of 60nm-100nm and a length of 400nm-800nm.

[0052] S2. Weigh out Ni(OH)2 powder, Co(NO3)2·6H2O and Mn(NO3)2 according to the preset molar ratio of Ni:Co:Mn=9:0.5:0.5.

[0053] S3. Dissolve the weighed Co(NO3)2·6H2O and Mn(NO3)2 in deionized water. The amount of deionized water added should be based on the concentration of Co and Mn ions in the deionized water being 0.05 mol / L. Add Ni(OH)2 powder.

[0054] Maintain the temperature at 60℃, add KOH with a concentration of 35g / L dropwise while stirring, control the pH value at 10, stir for 3.5h to obtain the precipitate;

[0055] S4. The precipitate is washed and dried to obtain the ternary cathode material, denoted as P-NCM90. Figure 3 As shown, rod-shaped cobalt and manganese particles precipitated on the surface of the prepared P-NCM90.

[0056] Subsequently, a high-nickel ternary cathode material prepared using the above method was used to prepare a cathode, denoted as NCM90. Figure 4 As shown, Ni, Co, and Mn elements are uniformly distributed in the particles, and from... Figure 5 It can be seen from this that it is a standard ternary material.

[0057] After the above positive electrode was fabricated into a lithium battery, charge-discharge tests were conducted. For example... Figure 6 As shown, the prepared lithium-ion battery exhibits a capacity decay of 12.97% after 200 charge-discharge cycles.

[0058] like Figure 7 and 8 It can be seen that the high-nickel ternary cathode material prepared by this invention has higher capacity retention and higher activity at different discharge rates compared with commercially available products.

[0059] Example 2

[0060] This invention provides a method for preparing a high-nickel ternary cathode material for lithium-ion batteries, comprising:

[0061] S1. Prepare Ni(OH)2 powder, wherein the Ni(OH)2 powder is composed of particles with a particle size of 10um-20um formed by Ni(OH)2 nanospindles with a diameter of 60nm-100nm and a length of 400nm-800nm.

[0062] S2. Weigh out Ni(OH)2 powder, Co(NO3)2·6H2O and Mn(NO3)2 according to the preset molar ratio of Ni:Co:Mn=8:1:1.

[0063] S3. Dissolve the weighed Co(NO3)2·6H2O and Mn(NO3)2 in deionized water. The amount of deionized water added should be based on the concentration of Co and Mn ions in the deionized water being 0.02 mol / L. Add Ni(OH)2 powder.

[0064] Maintain the temperature at 58℃, add KOH with a concentration of 30g / L dropwise while stirring, control the pH value at 10, stir for 3h to obtain the precipitate;

[0065] S4. The precipitate is washed and dried to obtain the ternary cathode material, denoted as P-NCM811. Rod-shaped cobalt and manganese particles are precipitated on the surface of the prepared P-NCM811.

[0066] Subsequently, a cathode was prepared using the high-nickel ternary cathode material prepared by the above method, denoted as NCM811. Figure 9 As shown, Ni, Co, and Mn elements are uniformly distributed in the particles, and it is a standard ternary material.

[0067] After the above positive electrode was fabricated into a lithium battery, charge-discharge tests were conducted. The prepared lithium-ion battery showed a capacity decrease of 16.85% after 200 charge-discharge cycles.

[0068] The high-nickel ternary cathode material prepared by this invention exhibits higher capacity retention and activity compared to commercially available products at different discharge rates.

[0069] Example 3

[0070] This invention provides a method for preparing a high-nickel ternary cathode material for lithium-ion batteries, comprising:

[0071] S1. Prepare Ni(OH)2 powder, wherein the Ni(OH)2 powder is composed of particles with a particle size of 10um-20um formed by Ni(OH)2 nanospindles with a diameter of 60nm-100nm and a length of 400nm-800nm.

[0072] S2. Weigh out Ni(OH)2 powder, Co(NO3)2·6H2O and Mn(NO3)2 according to the preset molar ratio of Ni:Co:Mn=92:4:4.

[0073] S3. Dissolve the weighed Co(NO3)2·6H2O and Mn(NO3)2 in deionized water. The amount of deionized water added should be based on the concentration of Co and Mn ions in the deionized water being 0.10 mol / L. Add Ni(OH)2 powder.

[0074] Maintain the temperature at 62℃, add KOH with a concentration of 40g / L dropwise while stirring, control the pH value at 10, stir for 4h, and obtain the precipitate;

[0075] S4. The precipitate is washed and dried to obtain the ternary cathode material, denoted as P-NCM92. Rod-shaped cobalt and manganese particles are precipitated on the surface of the prepared P-NCM92.

[0076] Subsequently, a high-nickel ternary cathode material prepared using the above method was used to prepare a cathode, denoted as NCM811, as follows: Figure 10As shown, Ni, Co, and Mn elements are uniformly distributed in the particles, making it a standard ternary material.

[0077] After the above positive electrode was fabricated into a lithium battery, charge-discharge tests were conducted. The prepared lithium-ion battery showed a capacity decrease of 16.33% after 200 charge-discharge cycles.

[0078] The high-nickel ternary cathode material prepared by this invention exhibits higher capacity retention and activity compared to commercially available products at different discharge rates.

[0079] Comparative Example 1

[0080] Unlike Example 1, in step S2 of this comparative example, Ni(OH)2 powder, Co(NO3)2·6H2O and Mn(NO3)2 are weighed according to the preset molar ratio of Ni:Co:Mn=6:2:2.

[0081] The morphology of the prepared ternary cathode material is as follows: Figure 11 As shown (without subsequent sintering), it can be seen that a large amount of cobalt and manganese deposits are deposited on the surface of the Ni(OH)2 particles. Figure 12 It can be seen that the sintering of excessive cobalt and manganese deposits resulted in the formation of impurity phases. For example... Figure 13 The NCM cathode prepared in this comparative example does not have the standard charge-discharge curve characteristics of ternary materials, and its capacity decays rapidly. After 200 charge-discharge cycles, the capacity of the prepared lithium-ion battery decreased by 38.74%.

[0082] Comparative Example 2

[0083] Unlike Example 1, in step S2 of this comparative example, Ni(OH)2 powder, Co(NO3)2·6H2O and Mn(NO3)2 are weighed according to the preset molar ratio of Ni:Co:Mn=94:3:3.

[0084] The morphology of the prepared ternary cathode material is as follows: Figure 14 As shown, because the content of Co and Mn deposited on the surface is very low, Co and Mn cannot diffuse evenly throughout all areas of the material during high-temperature sintering. This results in an indistinct layered structure in the material itself. Figure 15 It can be seen that the splitting peak of the layered structure is not obvious, which means that although their charge-discharge curves show the characteristic curves of ternary materials, their rate of return is very poor and their capacity decay is also fast. After 200 charge-discharge cycles, the capacity of the prepared lithium-ion battery decayed by 25.91%.

[0085] Comparative Example 3

[0086] Unlike Example 1, in step S3 of this comparative example, the weighed Co(NO3)2·6H2O and Mn(NO3)2 are dissolved in deionized water. The amount of deionized water added is based on the concentration of Co and Mn ions in the deionized water being 0.01 mol / L. Ni(OH)2 powder is also added.

[0087] Due to the slow deposition rate of Co and Mn and the relatively fast dissolution rate of Ni, the splitting peak of the layered structure is not obvious. Although their charge-discharge curves show the characteristic curves of ternary materials, their rate capability is very poor and the capacity decay is also fast. After 200 charge-discharge cycles, the prepared lithium-ion battery has a capacity decay of 29.64%.

[0088] Comparative Example 4

[0089] Unlike Example 1, in step S3 of this comparative example, the weighed Co(NO3)2·6H2O and Mn(NO3)2 are dissolved in deionized water. The amount of deionized water added is based on the concentration of Co and Mn ions in the deionized water being 0.11 mol / L. Ni(OH)2 powder is also added.

[0090] Due to the rapid deposition rate of Co and Mn, and the relatively fast dissolution rate of Ni, a large amount of cobalt and manganese deposits were deposited on the surface of Ni(OH)2 particles. After sintering, the excess cobalt and manganese deposits generated impurity phases, resulting in non-standard charge-discharge curve characteristics of ternary materials. Moreover, the capacity decayed rapidly. After 200 charge-discharge cycles, the prepared lithium-ion battery showed a capacity decay of 31.76%.

[0091] Comparative Example 5

[0092] Unlike Example 1, in step S3 of this comparative example, the temperature was maintained at 55°C, KOH with a concentration of 40 g / L was added dropwise and stirred, the pH value was controlled at 10, and the mixture was stirred for 4 hours to obtain a precipitate.

[0093] The low insulation temperature resulted in a slower dissolution rate of Ni, which in turn led to a faster deposition rate of Co and Mn. The slow dissolution rate of Ni resulted in an insufficient number of bonding sites for Co and Mn precipitates, leading to performance degradation. After 200 charge-discharge cycles, the capacity of the prepared lithium-ion battery decreased by 26.81%.

[0094] Comparative Example 6

[0095] Unlike Example 1, in step S3 of this comparative example, the temperature was maintained at 65°C, KOH with a concentration of 40 g / L was added dropwise and stirred, the pH value was controlled at 10, and the mixture was stirred for 4 hours to obtain a precipitate.

[0096] The high insulation temperature leads to a faster dissolution rate of Ni, creating more bonding sites for Co and Mn. The excess loss of Ni has a significant impact on the material structure, resulting in performance degradation. After 200 charge-discharge cycles, the battery capacity decreased by 30.69%.

[0097] Comparative Example 7

[0098] Unlike Example 1, in step S3 of this comparative example, the pH value is controlled to be 9.

[0099] With a lower pH, the precipitation rate of Co and Mn is significantly reduced, and more Ni is dissolved, making it impossible to maintain a good final layered structure. As a result, the rate capability is very poor, and the capacity decay is also faster. After 200 charge-discharge cycles, the prepared lithium-ion battery has a capacity decay of 42.72%.

[0100] Comparative Example 8

[0101] Unlike Example 1, in step S3 of this comparative example, the pH value is controlled to be 11.

[0102] The high pH level resulted in an extremely low Ni dissolution rate, failing to provide adhesion sites for Co and Mn precipitates. The prepared lithium-ion battery exhibited a 42.09% capacity decay after 200 charge-discharge cycles.

[0103] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a high-nickel ternary cathode material for lithium-ion batteries, characterized in that, The Ni content molar ratio is 80%~92%, and the process includes the following steps: Prepare Ni(OH)2 powder, wherein the Ni(OH)2 powder is composed of particles with a particle size of 10um-20um formed by Ni(OH)2 nanospindles with a diameter of 60nm-100nm and a length of 400nm-800nm; Weigh out Ni(OH)2 powder and soluble salts of Co and Mn according to the preset molar ratio of Ni, Co and Mn; Dissolve the soluble salts of Co and Mn in deionized water, and add Ni(OH)2 powder; Maintain the temperature at 58℃-62℃, add the precipitant dropwise and stir, control the pH value at 10, stir for 3-4 hours to obtain the precipitate; The precipitate is then washed and dried to obtain the final product.

2. The preparation method according to claim 1, characterized in that, The precipitant is an aqueous solution of KOH, and the solubility of the KOH aqueous solution is 30 g / L - 40 g / L.

3. The preparation method according to claim 1, characterized in that, The stirring speed is 800rpm-1200rpm.

4. The preparation method according to claim 1, characterized in that, The soluble salts of Co and Mn are Co(NO3)2·6H2O and Mn(NO3)2, respectively.

5. The preparation method according to claim 1, characterized in that, Maintain the temperature at 60℃.

6. The preparation method according to claim 1, characterized in that, Soluble salts of Co and Mn are dissolved in deionized water, and the amount of deionized water added satisfies the following conditions: the total molar concentration of Co ions and Mn ions is 0.02 mol / L-0.10 mol / L.

7. A high-nickel ternary cathode material for lithium-ion batteries, characterized in that, The high-nickel ternary cathode material for lithium-ion batteries is prepared using any one of the preparation methods described in claims 1-6.

8. A lithium-ion battery positive electrode, characterized in that, The positive electrode of the lithium-ion battery is prepared using the high-nickel ternary positive electrode material described in claim 7.

9. A lithium-ion battery, characterized in that, The lithium-ion battery uses the high-nickel ternary cathode material described in claim 7 to prepare the cathode. Alternatively, the positive electrode as described in claim 8 may be used.

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