High-nickel positive electrode precursor material, and preparation method therefor and use thereof

Abstract

The present application relates to the technical field of battery materials, and particularly relates to a high-nickel positive electrode precursor material, and a preparation method therefor and a use thereof. The method comprises: acquiring metal raw material components according to the stoichiometric ratio of metal elements in a high-nickel positive electrode precursor material; preparing the metal raw material components into a salt solution, adding the salt solution, a precipitant solution, and a complexing agent solution to a deoxygenated reaction base solution, and implementing a complex-precipitation reaction in a first inert atmosphere to obtain a crude product of the high-nickel positive electrode precursor material; and successively performing vacuum drying treatment on the crude product to obtain the high-nickel positive electrode precursor material, wherein the mass percentage content of CO2 in the high-nickel positive electrode precursor material is less than 0.1%. By reducing the carbon content in the high-nickel positive electrode precursor material, a decomposition reaction or side reaction of LiHCO3 and Li2CO3 with an electrolyte in the charging and discharging process is reduced, and the amount of produced CO2 is reduced, thereby mitigating the gas production problem and improving electrochemical performance of positive electrode materials and safety performance of batteries.

Description

High nickel cathode precursor material and preparation method and application thereof Technical Field

[0001] The present application belongs to the field of battery material technology, and in particular relates to a high-nickel positive electrode precursor material and a preparation method and application thereof. Background Art

[0002] With the development of the new energy industry, ternary materials have become the optimal lithium battery cathode material to replace lithium cobalt oxide due to their excellent electrochemical performance and low raw material costs. High-nickel ternary materials, in particular, have become the preferred material for power batteries. In the preparation of high-nickel cathode materials, to prevent the volatilization of the lithium source, an excess lithium source is typically added to the precursor (e.g., (1.05-1.2):1) and sintered at high temperature. This results in excess lithium on the surface of the high-nickel cathode material particles. After sintering, this residual lithium primarily exists on the surface of the material in the form of Li2O. Li2O reacts with the corresponding water and carbon dioxide to form physical and chemical compounds such as LiOH, LiHCO3, and Li2CO3. During the charge and discharge process, lithium salts such as LiHCO3 and Li2CO3 decompose in the presence of the electrolyte to produce CO2, which in turn causes expansion problems and seriously affects the safety and performance of the battery cell. Furthermore, the presence of residual lithium leads to numerous side reactions at the interface between the electrode and the electrolyte, reducing the material's discharge capacity and affecting battery performance. On the other hand, the nickel element in ternary materials is alkaline and easily absorbs moisture and CO2 when exposed to air. As the Ni content increases, the probability of it reacting with residual lithium on the surface to form LiOH and Li2CO3 increases. Therefore, residual lithium on the surface of high-nickel cathode materials is one of the main causes of gas and moisture production in battery cells. Reducing the residual lithium on the surface of high-nickel cathode materials can reduce gas and moisture production during battery cell operation, effectively solving or alleviating battery bloating and poor performance.

[0003] Currently, the traditional method for removing residual lithium is to use solution washing, including water washing and organic solvent washing. However, water washing not only wastes a certain amount of water resources, but also has a complex washing process requiring multiple washing steps. In addition, water washing may damage the surface structure of the material, thereby affecting the electrochemical performance of the positive electrode material.

[0004] Summary of the Invention

[0005] The purpose of this application is to provide a high-nickel positive electrode precursor material and a preparation method thereof, as well as a high-nickel positive electrode material, a positive electrode sheet, and a secondary battery, aiming to solve, to a certain extent, the gas and water production problems caused by residual lithium in the high-nickel positive electrode material.

[0006] To achieve the above application objectives, the technical solutions adopted in this application are as follows:

[0007] In a first aspect, the present application provides a method for preparing a high-nickel cathode precursor material, comprising the following steps:

[0008] According to the stoichiometric ratio of metal elements in the high-nickel cathode precursor material Ni x Co y Mn z Al w (OH)2, obtain the metal raw material components, where 0.80 < x < 0.90, 0.10 < y < 0.20, 0 ≤ z < 0.10, 0 ≤ w < 0.10, and x + y + z + w = 1;

[0009] After configuring the metal raw material components into a salt solution, add it to the deoxygenated reaction bottom liquid together with a precipitant solution and a complexing agent solution, and carry out a complexation precipitation reaction under a first inert atmosphere to obtain a crude product of the high-nickel cathode precursor material;

[0010] Vacuum dry the crude product in sequence to obtain the high-nickel cathode precursor material, and the mass percentage content of CO2 in the high-nickel cathode precursor material is less than 0.1%.

[0011] For the method for preparing a high-nickel cathode precursor material provided in the first aspect of the present application, after obtaining the metal raw material components according to the high-nickel cathode precursor material, configure them into a salt solution, and then add them to the reaction bottom liquid together with a precipitant and a complexing agent. Under inert conditions, ensure that there is no oxidation phenomenon in the materials, and carry out a complexation precipitation reaction. The metal raw material components, the complexing agent and the precipitant self-assemble in the reaction bottom liquid to generate a hydroxide precursor material. After obtaining the crude product of the high-nickel cathode precursor material, carry out vacuum drying, which can not only ensure a vacuum environment but also displace the water vapor generated after heating, ensure that the moisture of the materials is qualified, and make the mass percentage content of CO2 in the dried high-nickel cathode precursor material less than 0.1%. Carry out the complexation precipitation reaction under an inert atmosphere condition, and after obtaining the crude product at the end of the precursor synthesis, adopt vacuum drying. By adjusting conditions such as pressure, time, gas replenishment time, air extraction time, and cycle time at different stages during the drying process, the carbon content inside the high-nickel cathode precursor material can be reduced. By reducing the carbon content inside the high-nickel cathode precursor material, the reaction with residual lithium (Li2O) to produce LiHCO3 and Li2CO3 is reduced, the decomposition reaction or side reaction of LiHCO3 and Li2CO3 with the electrolyte during charge and discharge is reduced, the amount of CO2 generated is reduced, and thus the gas generation problem, the electrochemical performance of the cathode material and the safety performance of the battery are improved.

[0012] In a second aspect, the present application provides a high-nickel cathode precursor material, the mass percentage content of CO2 in the high-nickel cathode precursor material is less than 0.1%, and the chemical general formula of the high-nickel cathode precursor material is expressed as Ni x Co y Mnz Al w (OH)2, where 0.80 < x < 0.90, 0.10 < y < 0.20, 0 ≤ z < 0.10, 0 ≤ w < 0.10, and x + y + z + w = 1.

[0013] The mass percentage content of CO2 in the high-nickel cathode precursor material provided by this application is less than 0.1%, reducing the carbon content inside the high-nickel cathode precursor material, thereby reducing the reaction of carbon with residual lithium (Li2O) in the precursor material to produce LiHCO3 and Li2CO3, which is beneficial to reducing the decomposition reaction or side reaction of LiHCO3 and Li2CO3 with the electrolyte during charge and discharge, reducing the amount of CO2 generated, and further improving the gas generation problem and the electrochemical performance and safety performance of the cathode material.

[0014] In the third aspect, this application provides a high-nickel cathode material, which is prepared by sintering the high-nickel cathode precursor material prepared by the above method or the above high-nickel cathode precursor material with a lithium source. The high-nickel cathode material provided by this application is prepared by sintering the high-nickel cathode precursor material with a mass percentage content of CO2 less than 0.1% as described above with a lithium source. Since the ternary cathode material has inheritance for the precursor, the properties and physical and chemical indexes of the precursor material directly affect the cathode material. Therefore, the low-carbon content cathode precursor material will reduce the carbon dioxide content in the high-nickel cathode material. Thus, the reaction of carbon with residual lithium (Li2O) in the high-nickel cathode material to produce LiHCO3 and Li2CO3 is reduced, which is beneficial to reducing the decomposition reaction or side reaction of LiHCO3 and Li2CO3 with the electrolyte during charge and discharge, reducing the amount of CO2 generated, improving the gas generation problem, and further improving the structural stability of the high-nickel cathode material, increasing the cycle stability and service life of the cathode material, and thus improving the electrochemical performance and safety performance of the cathode material.

[0015] In the fourth aspect, this application provides a cathode sheet, and the cathode active material in the cathode sheet includes the above high-nickel cathode material.

[0016] The cathode sheet provided by this application, due to adopting the high-nickel cathode material with good structural stability, good cycle stability and long service life as described above, improves the stability and safety of the cathode sheet, and at the same time the cathode sheet has electrochemical performances such as high energy density.

[0017] In the fifth aspect, this application provides a secondary battery, and the cathode in the secondary battery includes the above cathode sheet.

[0018] The secondary battery of this application, because the cathode includes the cathode sheet with good stability, high safety and high energy density as described above, improves the electrochemical performances such as the energy density and cycle life of the secondary battery. Description of the Drawings

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0020] FIG1 is a schematic flow chart of a method for preparing a high-nickel cathode precursor material according to an embodiment of the present application;

[0021] FIG2 is a test graph of the carbon dioxide content in the high-nickel positive electrode precursor materials provided in Examples 1 to 3 and Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0022] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0023] In this application, the term "and / or" describes the relationship between associated objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0024] In this application, "at least one" means one or more, and "plurality" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b or c", or "at least one of a, b and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or multiple.

[0025] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. Some or all of the steps can be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0026] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The singular forms "a", "an" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise.

[0027] The weights of the relevant components mentioned in the examples of this specification may not only refer to the specific content of each component, but also represent the weight ratio between the components. Therefore, as long as the content of the relevant components in the examples of this specification is proportionally enlarged or reduced according to the examples of this specification, it is within the scope disclosed in the examples of this specification. Specifically, the mass in the examples of this specification may be μg, mg, g, kg, etc., which are mass units known in the chemical industry.

[0028] The terms "first" and "second" are used solely for descriptive purposes to distinguish objects, such as substances, from one another and should not be understood to indicate or imply relative importance or to implicitly specify the quantity of the technical features being referred to. For example, without departing from the scope of the embodiments of this application, a first XX may also be referred to as a second XX, and similarly, a second XX may also be referred to as a first XX. Thus, features defined as "first" or "second" may explicitly or implicitly include one or more of such features.

[0029] Currently, in the preparation of high-nickel cathode materials (NCA / NCM / NC / NCMA, etc.), in order to prevent the volatilization of the lithium source, an excess lithium source is generally added to the precursor for high-temperature sintering. This will result in excess lithium existing on the surface of the high-nickel cathode material particles. After sintering, this residual lithium mainly exists on the surface of the material in the form of Li2O. Li2O reacts with the corresponding water and carbon dioxide to form physical and chemical compounds such as LiOH, LiHCO3, and Li2CO3. Among them, lithium salts such as LiHCO3 and Li2CO3 will decompose under the action of the electrolyte during the charge and discharge process to produce CO2, which in turn causes expansion problems and seriously affects the safety performance of the battery cell. In addition, the presence of residual lithium can cause a large number of side reactions at the interface between the electrode and the electrolyte, reducing the discharge capacity of the material and affecting the performance of the battery. On the other hand, the nickel element in the high-nickel cathode material is alkaline and easily absorbs moisture and CO2 when exposed to air. As the Ni content increases, the probability of reacting with the residual lithium on the surface to form LiOH and Li2CO3 increases. Therefore, residual lithium on the surface of high-nickel cathode materials is one of the main causes of gas and moisture production in battery cells. Reducing the residual lithium on the surface of high-nickel cathode materials can reduce gas and moisture production during battery cell operation, effectively solving or alleviating battery bloating and poor performance.

[0030] At present, the traditional method of removing residual lithium is often carried out by solution washing, including water washing, organic solvent washing, etc. However, water washing not only wastes a certain amount of water resources, but also has a complex washing process and multiple washing methods. In addition, water washing may damage the surface structure of the material, thereby affecting the electrochemical performance of the positive electrode material. In some known technologies, the method for improving the surface residual alkalinity of high-nickel ternary positive electrode materials for lithium-ion batteries is to first reduce the surface residual lithium of the high-nickel ternary material by water washing, and then perform alcohol washing to replenish lithium and sintering after lithium replenishment to replenish the lithium lost in the water washing process. In addition, the washed material is further dried to remove moisture before the next step of the process can be carried out. This method has many operating steps, is difficult to control, has many washing methods, wastes a certain amount of resources, and also requires a certain amount of lithium source replenishment. The process is relatively complex and not easy to industrialize. In other known technologies, for the removal of residual alkali in high-nickel ternary positive electrode materials, a solvent (deionized water, oxalic acid, acetic acid, alcohol solution (preferably C1-C6)) is used to perform ultrasonic washing on the high-nickel ternary positive electrode material. On the one hand, this method has the risk of introducing other substances during the treatment process. On the other hand, ultrasonic treatment can easily affect the particle morphology and internal structure of the product (such as the shedding of fine whiskers or the presence of internal cracks, etc.), thereby affecting the performance of the product.

[0031] It can be seen that the current traditional method of removing residual lithium is basically carried out at the positive end, and rarely considers carbon reduction treatment at the upstream, that is, the precursor end, to reduce the carbon content (CO2) in the precursor material, reduce its reaction with residual lithium on the surface, and thus reduce the probability of side reactions to improve the performance of the material. In addition, the effect of residual lithium on the surface of high-nickel positive electrode materials on gas production is mainly caused by lithium compounds (LiOH and Li2CO3), especially Li2CO3, which react with the electrolyte. Therefore, controlling the carbon content in the material is one of the key methods to solve the problem of flatulence caused by residual lithium in high-nickel positive electrode materials.

[0032] Based on the above analysis, in order to improve the problems of residual lithium on the surface of high-nickel positive electrode materials, such as gelation of positive electrode material slurry, severe gas production, and flatulence in batteries, the applicant has provided a method for improving the gas production problem caused by residual lithium in high-nickel positive electrode materials. The method mainly starts from the front-end material of the positive electrode material, that is, the precursor, by reducing the carbon content (CO2) inside the precursor material and reducing the LiHCO3 and Li2CO3 produced by its reaction with residual lithium (Li2O). This reduces the decomposition reaction or side reaction of LiHCO3 and Li2CO3 with the electrolyte during the charge and discharge process, reduces the amount of CO2 produced, and thus improves the gas production problem, the electrochemical performance of the positive electrode material, and the safety performance of the battery.

[0033] For the convenience of explanation, this application is specifically described through the following examples.

[0034] In the first aspect of the embodiments of the present application, a method for preparing a high-nickel cathode precursor material is provided, including the following steps:

[0035] S10. Obtain metal raw material components according to the stoichiometric ratio of metal elements in Ni x Co y Mn z Al w (OH)2, where 0.80 < x < 0.90, 0.10 < y < 0.20, 0 ≤ z < 0.10, 0 ≤ w < 0.10, and x + y + z + w = 1;

[0036] S20. After configuring the metal raw material components into a salt solution, add them to the deoxygenated reaction bottom liquid together with a precipitant solution and a complexing agent solution, and perform a complexation precipitation reaction under a first inert atmosphere to obtain a crude product of the high-nickel cathode precursor material;

[0037] S30. Vacuum-dry the crude product in sequence to obtain the high-nickel cathode precursor material, and the mass percentage content of CO2 in the high-nickel cathode precursor material is lower than 0.1%.

[0038] The chemical general formula of the high-nickel cathode precursor material to be prepared by the method for preparing a high-nickel cathode precursor material provided in the first aspect of the embodiments of the present application is represented as Ni x Co y Mn z Al w(OH)2, where 0.80 < x < 0.90, 0.10 < y < 0.20, 0 ≤ z < 0.10, 0 ≤ w < 0.10, and x + y + z + w = 1; the proportion of nickel element in the metal elements is more than 80%, and the high nickel content is beneficial to improving the energy density of the cathode material. The presence of cobalt can make the material structure more stable, but too high content will reduce the capacity; the presence of manganese can reduce the cost and improve the safety performance. Doping with aluminum can reduce the degree of cation mixing and maintain the stability of the layered structure, improve the discharge voltage and the significant drop of the median voltage during the charge-discharge cycle of the cathode material, and improve its cycle performance. After obtaining the metal raw material components according to the high nickel cathode precursor material, a salt solution is prepared. The salt solution can be a mixed salt solution of each metal raw material component or a separate salt solution of each metal raw material component. Then, it is added to the reaction bottom liquid together with a precipitant and a complexing agent. Under inert conditions, it is ensured that there is no oxidation phenomenon of the materials, and a complexation precipitation reaction is carried out. The metal raw material components, the complexing agent and the precipitant self-assemble in the reaction bottom liquid to generate a hydroxide precursor material. After obtaining the crude product of the high nickel cathode precursor material, vacuum drying is carried out, which can ensure the vacuum environment and displace the water vapor generated after heating, ensure that the moisture of the materials is qualified, and make the mass percentage content of CO2 in the dried high nickel cathode precursor material less than 0.1%. The preparation method of the embodiment of the present application carries out a complexation precipitation reaction under an inert atmosphere condition, and after the synthesis of the precursor is completed and the crude product is obtained, vacuum drying is adopted. By adjusting conditions such as the pressure, time, gas supplementing time, air extraction time, and circulation time in different stages of the drying process, the carbon content inside the high nickel cathode precursor material is reduced. By reducing the carbon content inside the high nickel cathode precursor material, the reaction with residual lithium (Li2O) to produce LiHCO3 and Li2CO3 is reduced, the decomposition reaction or side reaction of LiHCO3 and Li2CO3 with the electrolyte during the charge-discharge process is reduced, the amount of CO2 generated is reduced, and thus the gas generation problem, the electrochemical performance of the cathode material and the safety performance of the battery are improved.

[0039] In some possible implementation manners, in the above step S10, the chemical general formula of the high nickel cathode precursor material is represented as Ni x Co y Mn z Al w(OH)2, where 0.80 < x < 0.90, 0.10 < y < 0.20, 0 ≤ z < 0.10, 0 ≤ w < 0.10, and x + y + z + w = 1. The high-nickel cathode materials in this application mainly include series such as NCM (nickel cobalt manganese), NCA (nickel cobalt aluminum), NC (nickel cobalt), and NCMA (nickel cobalt manganese aluminum). Compared with the traditional lithium cobalt oxide cathode materials, due to their high capacity, high nickel content, and low cobalt content, the high-nickel cathode materials show obvious advantages in reducing costs and improving energy density. In high-nickel cathode materials, different component ratios will bring different properties to the materials. Increasing nickel will increase the capacity of the material, thereby improving the energy density, but will deteriorate the cycling performance; the presence of cobalt can make the material structure more stable, but too high content will reduce the capacity; the presence of manganese can reduce costs and improve safety performance, but too high content will damage the layered structure of the material.

[0040] In some specific embodiments, in the high-nickel cathode material, the nickel content is above 80%. For example, ternary 811. Simply put, high-nickel ternary 811 means that the ratio of nickel, cobalt, and manganese in the cathode material becomes 80%, 10%, and 10%. This not only reduces the proportion of cobalt to make the cost controllable, but also ensures the energy density of the battery to a certain extent, greatly improving the battery's cruising range, service life, and safety.

[0041] In some specific embodiments, the obtained metal raw material components include at least one of a nickel source, a cobalt source, a manganese source, and an aluminum source. Among them, the nickel source includes one or more of nickel nitrate, nickel acetate, and nickel sulfate. The cobalt source includes one or more of cobalt nitrate, cobalt acetate, and cobalt sulfate. The manganese source includes one or more selected from manganese nitrate, manganese acetate, and manganese sulfate. The aluminum source includes one or more of aluminum nitrate, aluminum acetate, and aluminum sulfate.

[0042] In some possible implementation manners, in the above step S20, the ammonia value in the reaction bottom liquid is 8.0 g / L to 16.0 g / L, the pH value is 11.5 to 12.5, and the temperature is 50°C to 70°C. In this case, the ammonia value range, pH value range, and temperature conditions in the deoxygenated reaction bottom liquid fully ensure the subsequent complexation precipitation reaction of the raw material components. Exemplarily, the ammonia value in the reaction bottom liquid can be 8 - 10 g / L, 10 - 12 g / L, 12 - 14 g / L, 14 - 16 g / L, etc., the pH value can be 11.5 - 11.8, 11.8 - 12.0, 12.0 - 12.3, 12.3 - 12.5, etc., and the temperature can be 50 - 55°C, 55 - 60°C, 60 - 65°C, 65 - 70°C, etc.

[0043] In some specific embodiments, nitrogen, argon, helium, or other inert protective gas is introduced into a sealed reactor for 3 to 8 hours. During this process, deionized water is added to the main reactor to submerge the lower layer and stirred. Stirring is initiated at 300 to 650 rpm, and the temperature is controlled at 50-70°C. A complexing agent is then added to the main reactor to control the ammonia content to 8.0 to 16.0 g / L. Alkali solution is then added to adjust the pH of the system to 11.50 to 12.50, thereby obtaining a deoxygenated reaction solution.

[0044] In some possible implementations, the metal raw material component is configured into a salt solution and then added to the deoxygenated reaction base liquid with a precipitant solution and a complexing agent solution, and a complex precipitation reaction is carried out under the conditions of a first inert atmosphere. The conditions of the complex precipitation reaction include: carrying out the complex precipitation reaction under the conditions of an ammonia value of 8.0g / L to 16.0g / L, a pH value of 11.5 to 12.5, and an inert atmosphere flow rate of 300L / h to 600L / h. In this case, the inert atmosphere effectively ensures that no oxidation of the material occurs, and the ammonia value range and the pH value range fully ensure the complex reaction of the metal raw material component with the complexing agent, so as to react with the precipitant to precipitate high-nickel positive electrode precursor particles. Wherein, the first inert atmosphere includes at least one of nitrogen, argon, and helium. Illustratively, the ammonia value can be 8-10 g / L, 10-12 g / L, 12-14 g / L, 14-16 g / L, etc., the pH value can be 11.5-11.8, 11.8-12.0, 12.0-12.3, 12.3-12.5, etc., and the inert atmosphere flow rate can be 300-400 L / h, 400-500 L / h, 500-600 L / h, etc.

[0045] In some possible implementations, after the complex precipitation reaction is carried out until the particle size of the product is stabilized at 4.5 μm to 5.5 μm, the third inert atmosphere flow rate is 1 m 3 / h~5m 3 / h for aging treatment, and filter to obtain a crude product. In this case, when the particle size of the product generated by the complex precipitation reaction reaches 4.5μm~5.5μm, an aging reaction is carried out in an inert environment, and the reaction system solution is allowed to stand for a period of time under certain conditions, so that the components in the reaction system are fully reacted, and the suspended matter is fully settled, and the high-nickel positive electrode precursor particles are fully self-assembled to obtain crude product particles with more complete morphology, reduce material loss, and also improve the washing efficiency of subsequent materials. Among them, the third inert atmosphere includes at least one of nitrogen, argon, and helium. Exemplarily, the particle size of the crude product can be 4.5~4.8μm, 4.8~5μm, 5~5.2μm, 5.2~5.5μm, etc. The flow rate of the third inert atmosphere can be 1~2m 3 / h, 2~3m 3 / h, 3~4m 3 / h, 4~5m 3 / h, etc.

[0046] In some specific embodiments, the metal raw material components are configured into a salt solution and then added to the reactor simultaneously with the precipitant solution and the complexing agent solution while maintaining the inert gas flow. During this period, the pH value of the system is maintained at 11.50-12.50, the ammonia value is 8.0-16.0 g / L, and the inert atmosphere is protected throughout the process. The inert atmosphere flow rate is 300-600 L / h to ensure that the material is not oxidized. When the reactor is full, the unqualified overflow is opened until the particle size is stably controlled at 4.5-5.5 um. Then, the qualified overflow is opened to the aging tank. The aging tank is opened with inert atmosphere protection in advance, and the inert atmosphere flow rate is 1-5 m 3 When the amount of the aging tank is sufficient for filter press washing, filter press washing is performed to obtain a crude product of the high-nickel positive electrode precursor material for standby use.

[0047] In some possible implementations, the concentration of the salt solution is 1.0 mol / L to 2.5 mol / L. The salt solution can be a separate concentration of raw material components in the form of oxides, salts, hydroxides, etc. of metal elements such as nickel, cobalt, manganese, and aluminum, or a mixed salt solubility of raw material components of metal elements such as nickel, cobalt, manganese, and aluminum. Salt solutions of this concentration are conducive to subsequent reactions with complexing agents and precipitants to form high-nickel positive electrode precursor materials. Exemplarily, the concentration of the salt solution can be 1 to 1.5 mol / L, 1.5 to 2 mol / L, 2 to 2.5 mol / L, etc.

[0048] In some possible implementations, the concentration of the precipitant solution is 8 mol / L to 15 mol / L. In some possible implementations, the precipitant in the precipitant solution includes at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, and sodium acetate. These precipitants and their concentrations used in the embodiments of the present application fully ensure the subsequent precipitation of the metal raw material component complex to form high-nickel positive electrode precursor particles. Exemplarily, the concentration of the precipitant solution can be 8 to 10 mol / L, 10 to 12 mol / L, 12 to 14 mol / L, 13 to 15 mol / L, etc.

[0049] In some possible implementations, the concentration of the complexing agent solution is 150 g / L to 200 g / L. In some possible implementations, the complexing agent in the complexing agent solution includes at least one of ammonia, citric acid, organic phosphate, and ethylenediaminetetraacetic acid. The complexing agent and its concentration used in the embodiments of the present application are conducive to subsequent complexing reaction with the metal raw material component to form a complex. Exemplarily, the concentration of the complexing agent solution can be 150 to 160 g / L, 160 to 170 g / L, 170 to 180 g / L, 180 to 190 g / L, 190 to 200 g / L, etc.

[0050] In some possible implementation manners, in the above step S30, the temperature condition for the vacuum drying treatment is 110°C to 150°C, and the duration is 10 h to 20 h. Under such vacuum pumping conditions, both the vacuum environment is ensured and the water vapor generated after heating can be replaced, the water vapor in the crude product is excluded, and the water content in the crude product is ensured to be low and qualified.

[0051] In some embodiments, the vacuum drying treatment includes a vacuum pumping drying stage and an inert atmosphere supplement drying stage. By adopting two-stage vacuum pumping drying, the first stage is the vacuum pumping operation, and the second stage is the inert atmosphere supplement operation. The two steps are set simultaneously, which can better ensure the vacuum environment and replace the water vapor generated after heating, ensuring that the moisture of the material is qualified.

[0052] In some specific embodiments, the conditions for vacuum pumping drying include: drying for 1 min to 15 h under the conditions of a temperature of 110°C to 50°C and a pressure of 50 Pa to 100,000 Pa. Under such vacuum pumping conditions, both the vacuum environment is ensured and the water vapor generated after heating can be replaced, the water vapor in the crude product is excluded, and the water content in the crude product is ensured to be low and qualified.

[0053] In some possible implementation manners, the conditions for inert atmosphere supplement drying include: drying for 1 min to 15 h under the conditions of a temperature of 110°C to 50°C, a pressure of 0 Pa to 100,000 Pa and greater than the pressure in the system after vacuum pumping drying, and a second inert atmosphere flow rate of 8 kPa / min to 12 kPa / min. Under such inert atmosphere supplement drying conditions, not only can the crude product be further dried, but also the water vapor and carbon dioxide in the crude product can be fully excluded through the inert atmosphere. The pressure is set to be greater than the pressure in the system after vacuum pumping drying, ensuring that the inert atmosphere can fully replace and exclude the water vapor and carbon dioxide and other gases in the crude product, so that the mass percentage content of CO2 in the high-nickel cathode precursor material is less than 0.1%. Among them, the second inert atmosphere includes at least one of nitrogen, argon, and helium.

[0054] In a second aspect, the embodiments of the present application provide a high-nickel cathode precursor material, in which the mass percentage content of CO2 in the high-nickel cathode precursor material is less than 0.1%, and the chemical general formula of the high-nickel cathode precursor material is expressed as Ni x Co y Mn z Al w (OH)2, where 0.80 < x < 0.90, 0.10 < y < 0.20, 0 ≤ z < 0.10, 0 ≤ w < 0.10, and x + y + z + w = 1.

[0055] The mass percentage content of CO2 in the high-nickel cathode precursor material provided by the embodiments of the present application is less than 0.1%, which reduces the carbon content inside the high-nickel cathode precursor material, thereby reducing the reaction of carbon in the precursor material with residual lithium (Li2O) to produce LiHCO3 and Li2CO3, which is beneficial to reducing the decomposition reaction or side reaction of LiHCO3 and Li2CO3 with the electrolyte during charge and discharge, reducing the amount of CO2 generated, and further improving the gas generation problem, the electrochemical performance of the cathode material and the safety performance of the battery.

[0056] In some possible implementation manners, the chemical general formula of the high-nickel cathode precursor material is expressed as Ni x Co y Mn z Al w (OH)2, where 0.80 < x < 0.90, 0.10 < y < 0.20, 0 ≤ z < 0.10, 0 ≤ w < 0.10, and x + y + z + w = 1. The high-nickel cathode materials of the present application mainly include series such as NCM (nickel-cobalt-manganese), NCA (nickel-cobalt-aluminum), NC (nickel-cobalt), and NCMA (nickel-cobalt-manganese-aluminum). Compared with the traditional lithium cobalt oxide cathode material, the high-nickel cathode material has obvious advantages in reducing costs and improving energy density due to its high capacity, high nickel content, and low cobalt content. In the high-nickel cathode material, different component ratios will bring different performances to the material. Increasing nickel will increase the capacity of the material, thereby improving the energy density, but will make the cycling performance worse; the presence of cobalt can make the material structure more stable, but too high content will reduce the capacity; the presence of manganese can reduce costs and improve safety performance, but too high content will damage the layered structure of the material.

[0057] In some possible implementation manners, the average particle size of the high-nickel cathode precursor material is 4.5 - 5.5 μm, and the high-nickel cathode precursor material with this particle size range is beneficial to preparing a high-nickel cathode material with a large specific surface area. Specifically, the average particle size of the high-nickel cathode precursor material can be 4.5 - 4.8 μm, 4.8 - 5.0 μm, 5.0 - 5.2 μm, 5.2 - 5.5 μm, etc.

[0058] In a third aspect, the embodiments of the present application provide a high-nickel cathode material, which is prepared by sintering the high-nickel cathode precursor material prepared by the above method or the above high-nickel cathode precursor material and a lithium source.

[0059] The high-nickel positive electrode material provided in the embodiment of the present application is prepared by sintering the high-nickel positive electrode precursor material having a mass percentage of CO2 less than 0.1% and a lithium source, and the ternary positive electrode material inherits the precursor, and the properties and physical and chemical indicators of the precursor material directly affect the positive electrode material. Therefore, the positive electrode precursor material with a low carbon content will reduce the content of carbon dioxide in the high-nickel positive electrode material. This reduces the reaction of carbon with residual lithium (Li2O) in the high-nickel positive electrode material to produce LiHCO3 and Li2CO3, which is beneficial to reducing the decomposition reaction or side reaction of LiHCO3 and Li2CO3 with the electrolyte during the charge and discharge process, reducing the amount of CO2 produced, improving the gas production problem, and thus improving the structural stability of the high-nickel positive electrode material, improving the cycle stability and service life of the positive electrode material, thereby improving the electrochemical performance of the positive electrode material and the safety performance of the battery.

[0060] In some possible implementations, a method for preparing a high-nickel cathode material is provided, comprising the following steps: mixing a high-nickel cathode precursor material with a lithium source and sintering the mixture to obtain the cathode material; wherein the mixing and sintering temperature is 300-1000°C. The high-nickel cathode material particles are obtained by grinding or crushing.

[0061] In some possible implementations, the lithium source is selected from one or more of lithium carbonate, lithium hydroxide monohydrate, lithium acetate, lithium nitrate, lithium oxalate, lithium acetate, lithium hydroxide, and lithium oxide. These lithium salts can be sintered with high-nickel positive electrode precursor materials to form positive electrode materials.

[0062] In some possible implementations, the molar ratio of the high-nickel cathode precursor material to the lithium source is 1:(1-1.1). This ratio facilitates the full reaction between the cathode precursor material and the lithium salt to form the cathode material. By controlling the molar ratio of the high-nickel cathode precursor material to the lithium source, the resulting cathode material can be guaranteed to have high capacity and cycle performance.

[0063] In a fourth aspect, an embodiment of the present application provides a positive electrode sheet, in which the positive electrode active material includes the above-mentioned high-nickel positive electrode material.

[0064] The positive electrode sheet provided in the embodiment of the present application improves the stability and safety of the positive electrode sheet due to the use of the high-nickel positive electrode material with good structural stability, good cycle stability and long service life. At the same time, the positive electrode sheet has electrochemical properties such as high energy density.

[0065] In some possible implementations, the positive electrode sheet includes a current collector and a positive electrode active material layer that are laminated and bonded together. The positive electrode active material layer includes the above-mentioned high-nickel positive electrode material, a conductive agent, a binder, and the like.

[0066] In some possible implementations, the preparation process of making a positive electrode sheet from a positive electrode active material includes but is not limited to: mixing the above-mentioned high-nickel positive electrode material, conductive agent and binder to obtain an electrode slurry, coating the electrode slurry on a current collector, and preparing a positive electrode sheet through steps such as drying, rolling, and die cutting.

[0067] In some possible implementations, the content of the binder in the positive electrode active slurry is 2 wt%-4 wt%. In specific embodiments, the content of the binder can be 2 wt%, 3 wt%, 4 wt%, etc., which are typical but not limiting contents.

[0068] In some possible implementations, the binder includes one or more of polyvinylidene chloride, soluble polytetrafluoroethylene, styrene-butadiene rubber, hydroxypropyl methylcellulose, methylcellulose, carboxymethylcellulose, polyvinyl alcohol, acrylonitrile copolymer, sodium alginate, chitosan, and chitosan derivatives.

[0069] In some possible implementations, the content of the conductive agent in the electrode slurry is 3 wt%-5 wt%. In specific embodiments, the content of the conductive agent can be 3 wt%, 4 wt%, 5 wt%, etc., which are typical but not limiting contents.

[0070] In some possible implementations, the conductive agent includes one or more of graphite, carbon black, acetylene black, graphene, carbon fiber, C60, and carbon nanotubes.

[0071] In some possible implementations, the positive electrode current collector includes but is not limited to any one of copper foil and aluminum foil.

[0072] In a fifth aspect, an embodiment of the present application provides a secondary battery, wherein the positive electrode of the secondary battery includes the above-mentioned positive electrode sheet.

[0073] The secondary battery of the embodiment of the present application has improved electrochemical properties such as energy density and cycle life of the secondary battery because the positive electrode includes the positive electrode sheet with good stability, high safety and high energy density.

[0074] The secondary battery in the embodiments of this application can be a lithium-ion battery or a lithium metal battery. The secondary battery includes a positive electrode, a negative electrode, a separator, and an electrolyte. This application does not specifically limit the negative electrode, electrolyte, separator, and other components of the secondary battery in the embodiments, and is applicable to any battery system.

[0075] In some possible implementations, the negative electrode of the secondary battery includes but is not limited to carbon materials such as graphite, soft carbon (such as coke), hard carbon, or nitrides, tin-based oxides, tin-based oxides, tin alloys, and nano-negative electrode materials.

[0076] In some possible implementations, the separator includes at least one material selected from the group consisting of polypropylene fiber, polyacrylonitrile fiber, polyvinyl formal fiber, poly(ethylene terephthalate), polyethylene terephthalate, polyamide fiber, and poly(p-phenylene terephthalamide).

[0077] In some possible implementations, the electrolyte includes at least one soluble lithium salt.

[0078] In order to make the above implementation details and operations of this application clearly understood by those skilled in the art, as well as to significantly demonstrate the advanced performance of the high-nickel positive electrode precursor material and its preparation method and application in the embodiments of this application, the above technical solution is illustrated by multiple embodiments below.

[0079] For high nickel materials, when the Ni content of the Ni-rich positive electrode is less than 60%, the impact caused by residual lithium is acceptable, and this type of material has been successfully used commercially. However, when the Ni content is higher than 80%, its residual lithium compound (Li2O) comes into contact with CO2 and H2O and is converted into LiOH, LiHCO3 and Li2CO3, which produce many adverse effects during the charge and discharge process (electrolyte condensation, flatulence, etc.). Therefore, the embodiment of this application uses Ni with a Ni content higher than 80% 0.85 Co 0.15 (OH)2 nickel cobalt hydroxide precursor was taken as the research object.

[0080] Example 1

[0081] A Ni 0.85 Co 0.15 The (OH)2 nickel cobalt hydroxide precursor material is prepared by the following steps:

[0082] ① Prepare a nickel-cobalt salt solution with a metal ion concentration of 2 mol / L, a sodium hydroxide solution with a concentration of 11 mol / L, and an ammonia solution with a concentration of 180 g / L.

[0083] ②Pour nitrogen into the sealed reactor for 5 hours. During this time, add deionized water to the main reactor to cover the lower layer and stir. Turn on the stirring at 590 rpm and control the temperature at 60°C.

[0084] ③ Add complexing agent ammonia water to the main reactor in sequence, control the ammonia value at 12.0g / L, and add alkali solution to adjust the pH of the system to 12.1, which serves as the base liquid and starting condition for the reaction.

[0085] ④ Add nickel cobalt salt solution, sodium hydroxide solution and ammonia solution into the reactor at the same time and maintain the inert gas flow. During this period, the pH of the system is maintained at 12.1 and the ammonia value is maintained at 12 g / L. Nitrogen protection is used throughout the process at 400 L / h to ensure that there is no oxidation of the material.

[0086] ⑤ When the reactor is full, open the overflow of unqualified products until the particle size is stably controlled at 4.5-5.5um, open the overflow of qualified products to the aging tank, and open the nitrogen protection in the aging tank in advance, with a nitrogen volume of 3m 3 / h.

[0087] ⑥ When the amount of the aging tank meets the requirements for washing the filter press, washing is carried out to obtain the corresponding binary high-nickel precursor for use.

[0088] ⑦Place the filter cake in a vacuum drying oven, set the temperature to 110℃, dry for 10h, set the vacuum pressure to 3000Pa in the first stage, hold the pressure for 720min, do not set the nitrogen supply pressure in the second stage, and the vacuum pump will be in working state all the time. This process was carried out for 3 batches of experiments, and the Ni 0.85 Co 0.15 The physical and chemical properties of (OH)2 nickel cobalt hydroxide precursor material are shown in Table 1 below.

[0089] Table 1

[0090] Example 2

[0091] A Ni 0.85 Co 0.15 The (OH)2 nickel cobalt hydroxide precursor material is prepared by the following steps:

[0092] ① Prepare a nickel-cobalt salt solution with a metal ion concentration of 2 mol / L, a sodium hydroxide solution with a concentration of 11 mol / L, and an ammonia solution with a concentration of 180 g / L.

[0093] ②Pour nitrogen into the sealed reactor for 5 hours. During this time, add deionized water to the main reactor to cover the lower layer and stir. Turn on the stirring at 590 rpm and control the temperature at 60°C.

[0094] ③ Add complexing agent ammonia water to the main reactor in sequence, control the ammonia value at 12.0g / L, and add alkali solution to adjust the pH of the system to 12.1, which serves as the base liquid and starting condition for the reaction.

[0095] ④ Add nickel cobalt salt solution, sodium hydroxide solution and ammonia solution into the reactor at the same time and maintain the inert gas flow. During this period, the pH of the system is maintained at 12.1 and the ammonia value is maintained at 12 g / L. Nitrogen protection is used throughout the process at 400 L / h to ensure that there is no oxidation of the material.

[0096] ⑤ When the reactor is full, open the overflow of unqualified products until the particle size is stably controlled at 4.5-5.5um, open the overflow of qualified products to the aging tank, and open the nitrogen protection in the aging tank in advance, with a nitrogen volume of 3m 3 / h.

[0097] ⑥ When the amount of the aging tank meets the requirements for washing the filter press, washing is carried out to obtain the corresponding binary high-nickel precursor for use.

[0098] ⑦Place the filter cake in a vacuum drying oven, set the temperature to 110℃, dry for 10 hours, set the vacuum pressure to 3000Pa in the first stage, hold the pressure for 1 minute, and enter the second stage in time, the nitrogen filling pressure in the second stage is 50000Pa, hold the pressure for 1 minute, and ensure the two-stage cycle. After drying, Ni 0.85 Co 0.15 Three batches of experiments were conducted on the (OH)2 nickel cobalt hydroxide precursor material, and its physical and chemical properties are shown in Table 2 below.

[0099] Table 2

[0100] Example 3

[0101] A Ni 0.85 Co 0.15 The (OH)2 nickel cobalt hydroxide precursor material is prepared by the following steps:

[0102] ① Prepare a nickel-cobalt salt solution with a metal ion concentration of 2 mol / L, a sodium hydroxide solution with a concentration of 11 mol / L, and an ammonia solution with a concentration of 180 g / L.

[0103] ②Pour nitrogen into the sealed reactor for 5 hours. During this time, add deionized water to the main reactor to cover the lower layer and stir. Turn on the stirring at 590 rpm and control the temperature at 60°C.

[0104] ③ Add complexing agent ammonia water to the main reactor in sequence, control the ammonia value at 12.0g / L, and add alkali solution to adjust the pH of the system to 12.1, which serves as the base liquid and starting condition for the reaction.

[0105] ④ Add nickel cobalt salt solution, sodium hydroxide solution and ammonia solution into the reactor at the same time and maintain the inert gas flow. During this period, the pH of the system is maintained at 12.1 and the ammonia value is maintained at 12 g / L. Nitrogen protection is used throughout the process at 400 L / h to ensure that there is no oxidation of the material.

[0106] ⑤ When the reactor is full, open the overflow of unqualified products until the particle size is stably controlled at 4.5-5.5um, open the overflow of qualified products to the aging tank, and open the nitrogen protection in the aging tank in advance, with a nitrogen volume of 3m 3 / h.

[0107] ⑥ When the amount of the aging tank meets the requirements for washing the filter press, washing is carried out to obtain the corresponding binary high-nickel precursor for use.

[0108] ⑦Place the above filter cake in a vacuum drying oven, set the temperature to 110℃, dry for 12h, set the vacuum pressure to 3000Pa in the first stage, hold the pressure for 1min, and enter the second stage in time. Nitrogen is added to 100000Pa (normal pressure) in the second stage, and the pressure is held for 1min. The process ensures the two-stage cycle. Fully ensure the replacement of nitrogen to further reduce the moisture content. After drying, Ni 0.85 Co 0.15 Three batches of experiments were conducted on the (OH)2 nickel cobalt hydroxide precursor material, and its physical and chemical properties are shown in Table 3 below.

[0109] Table 3

[0110] Comparative Example 1

[0111] A Ni 0.85 Co 0.15 The (OH)2 nickel cobalt hydroxide precursor material is prepared by the following steps:

[0112] ① Prepare a nickel-cobalt salt solution with a metal ion concentration of 2 mol / L, a sodium hydroxide solution with a concentration of 11 mol / L, and an ammonia solution with a concentration of 180 g / L.

[0113] ②Pour nitrogen into the sealed reactor for 5 hours. During this time, add deionized water to the main reactor to cover the lower layer and stir. Turn on the stirring at 590 rpm and control the temperature at 60°C.

[0114] ③ Add complexing agent ammonia water to the main reactor in sequence, control the ammonia value at 12.0g / L, and add alkali solution to adjust the pH of the system to 12.1, which serves as the base liquid and starting condition for the reaction.

[0115] ④ Add nickel cobalt salt solution, sodium hydroxide solution and ammonia solution into the reactor at the same time and maintain the inert gas flow. During this period, the pH of the system is maintained at 12.1 and the ammonia value is maintained at 12 g / L. Nitrogen protection is used throughout the process at 400 L / h to ensure that there is no oxidation of the material.

[0116] ⑤ When the reactor is full, open the overflow of unqualified products until the particle size is stably controlled at 4.5-5.5um, open the overflow of qualified products to the aging tank, and open the nitrogen protection in the aging tank in advance, with a nitrogen volume of 3m 3 / h.

[0117] ⑥ When the amount of the aging tank meets the requirements for washing the filter press, washing is carried out to obtain the corresponding binary high-nickel precursor for use.

[0118] ⑦Place the filter cake in a common drying oven at 110℃ for 10h. When the moisture content is less than 0.30%, turn off the heating and send the dried sample for inspection and analysis. This drying method was used for a total of nine batches of experiments. After the drying was completed, Ni 0.85 Co 0.15 Nine batches of experiments were conducted on the (OH)2 nickel cobalt hydroxide precursor material, and its physical and chemical properties are shown in Table 4 below.

[0119] Table 4

[0120] The test graph of the percentage of carbon dioxide in the samples ZK-1 to ZK-9 prepared by vacuum drying in the above Examples 1 to 3 and the samples PG-1 to PG-9 prepared by conventional drying in Comparative Example 1 is shown in FIG2 .

[0121] It can be seen from the above test results that the carbon content (CO2) in the high-nickel positive electrode precursor material obtained by vacuum drying in the embodiment of the present application is basically less than 0.1%, while the carbon content level of the high-nickel positive electrode precursor material obtained by ordinary drying in Comparative Example 1 is greater than 0.1%, averaging about 0.25%. The reduction in carbon content in the high-nickel positive electrode precursor material obtained by vacuum drying in the embodiment of the present application reduces the probability of its reaction with residual lithium (Li2O) to generate Li2CO3 and LiHCO3 during the sintering of the high-nickel positive electrode material, thereby avoiding the self-decomposition of these lithium carbonates or the reaction with the electrolyte to produce carbon dioxide gas during the charge and discharge process, greatly improving the safety performance of the material, and at the same time improving the electrochemical energy of the material.

[0122] In addition, by comparing Example 1 with Examples 2 and 3, it can be seen that since the second stage of nitrogen replacement operation was carried out during vacuum drying in Example 1, the water content in the prepared high-nickel positive electrode precursor material was relatively high. Although LiOH generated by the reaction of water with residual lithium has a certain impact on the positive electrode material, it will not have the risk of gas production after reacting with residual lithium like CO2, affecting safety.

[0123] Furthermore, the Ni prepared in Examples 1 to 3 and Comparative Example 1 0.85 Co 0.15 (OH)2 nickel-cobalt hydroxide precursors (all products from the first batch were used for the experiment) were prepared into positive electrode materials. The preparation steps included: mixing the nickel-cobalt binary precursors prepared in Examples 1-3 and Comparative Example 1 with lithium hydroxide in a ratio of 1:1.05, and calcining them in a tube furnace under an oxygen atmosphere by heating to 450°C and holding for 6 hours, then heating to 750°C and holding for 15 hours to form nickel-cobalt binary positive electrode materials. The materials were then sieved, demagnetized, and packaged to obtain nickel-cobalt positive electrode materials.

[0124] The content of residual alkali in the prepared nickel-cobalt positive electrode materials was tested respectively. The residual alkali is generally represented by the content of lithium carbonate. Therefore, the content of lithium carbonate in the positive electrode material was tested. The test results are shown in Table 5 below:

[0125] Table 5

[0126] From the test results in Table 5 above, it can be seen that the Ni 0.85 Co 0.15 The (OH)2 nickel cobalt hydroxide precursor material has a low residual alkali content of only 0.08% to 0.15% in the cathode material made from the nickel cobalt hydroxide precursor material provided in Comparative Example 1, which is much lower than the residual alkali content of 0.58%. This improves the gas production problem and significantly improves the safety and cycle stability of the cathode material made from the precursor material of the present application embodiment.

[0127] Furthermore, the Ni prepared in Examples 1 to 3 and Comparative Example 1 0.85 Co 0.15 (OH)2 nickel cobalt hydroxide precursors were respectively made into positive electrode materials and applied to secondary batteries. The preparation thereof included the following steps: respectively weighing the same mass of nickel cobalt positive electrode materials prepared using the precursors of the above-mentioned Examples 1-3 and Comparative Example 1, and preparing button half-cells according to the active material: acetylene black: PVDF = 91:4.5:4.5, and using a metal lithium sheet as the negative electrode to obtain a secondary battery.

[0128] The secondary batteries prepared in accordance with Examples 1 to 3 and Comparative Example 1 were subjected to electrochemical performance tests at 2.75-4.30 V and 200-cycle performance tests at room temperature. The test results of 0.1C gram capacity and 200-cycle performance retention are shown in Table 6 below:

[0129] Table 6

[0130] From the test results in Table 6 above, it can be seen that the Ni 0.85 Co 0.15 The secondary battery made of (OH)2 nickel cobalt hydroxide precursor material shows a higher gram capacity under 0.1C conditions, among which the gram capacity of the secondary battery corresponding to Example 3 is as high as 201.4MAh / g. 0.85 Co 0.15 The secondary battery made of (OH)2 nickel cobalt hydroxide precursor material showed better capacity retention rate of 86% after 200 cycles of charge and discharge, and had better cycle stability.

[0131] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A method for preparing a high-nickel positive electrode precursor material, characterized in that: The following steps are involved: According to the stoichiometric ratio of metal elements in the high-nickel cathode precursor material Ni x Co y Mn z Al w (OH)2, obtain the metal raw material components, where 0.80 < x < 0.90, 0.10 < y < 0.20, 0 ≤ z < 0.10, 0 ≤ w < 0.10, and x + y + z + w = 1; The metal raw material components are configured into a salt solution, and then added to the deoxygenated reaction base solution together with a precipitant solution and a complexing agent solution, and a complexing precipitation reaction is performed under a first inert atmosphere to obtain a crude product of a high-nickel positive electrode precursor material; The crude product is subjected to vacuum drying treatment in sequence to obtain a high-nickel positive electrode precursor material, wherein the mass percentage of CO2 in the high-nickel positive electrode precursor material is less than 0.1%.

2. The method for preparing a high-nickel positive electrode precursor material according to claim 1, characterized in that: The vacuum drying process includes a vacuum drying stage and an inert atmosphere drying stage; And / or, the temperature condition of the vacuum drying treatment is 110° C. to 150° C., and the duration is 10 h to 20 h.

3. The method for preparing a high-nickel positive electrode precursor material according to claim 2, characterized in that: The conditions of the vacuum drying stage include: drying for 1 min to 15 h at a temperature of 110° C. to 50° C. and a pressure of 50 Pa to 100000 Pa; And / or, the conditions of the supplementary inert atmosphere drying stage include: drying for 1 min to 15 h at a temperature of 110°C to 50°C, a pressure of 0 Pa to 100000 Pa and greater than the pressure in the system after vacuum drying, and a second inert atmosphere flow rate of 8 kPa / min to 12 kPa / min.

4. The method for preparing a high-nickel positive electrode precursor material according to claim 3, characterized in that: The ammonia content of the reaction bottom solution is 8.0 g / L to 16.0 g / L, the pH value is 11.5 to 12.5, and the temperature is 50° C. to 70° C.; And / or, the conditions of the complex precipitation reaction include: carrying out the complex precipitation reaction under the conditions of an ammonia value of 8.0 g / L to 16.0 g / L, a pH value of 11.5 to 12.5, and an inert atmosphere flow rate of 300 L / h to 600 L / h.

5. The method for preparing a high-nickel positive electrode precursor material according to claim 4, characterized in that: After the complex precipitation reaction is carried out until the particle size of the product is stabilized at 4.5 μm to 5.5 μm, the third inert atmosphere flow rate is 1 m 3 / h~5m 3 / h for aging treatment, and filtering to obtain the crude product.

6. The method for preparing a high-nickel positive electrode precursor material according to claim 5, characterized in that: The concentration of the salt solution is 1.0 mol / L to 2.5 mol / L; and / or, the concentration of the precipitant solution is 8 mol / L to 15 mol / L; and / or, the concentration of the complexing agent solution is 150 g / L to 200 g / L; And / or, the precipitant in the precipitant solution includes at least one of sodium hydroxide, potassium hydroxide, sodium carbonate and sodium acetate; And / or, the complexing agent in the complexing agent solution includes at least one of ammonia water, citric acid, organic phosphate, and ethylenediaminetetraacetic acid; And / or, the first inert atmosphere, the second inert atmosphere, and the third inert atmosphere each independently include at least one of nitrogen, argon, and helium.

7. A high nickel cathode precursor material, characterized in that: The mass percentage content of CO2 in the high-nickel cathode precursor material is less than 0.1%, and the chemical general formula of the high-nickel cathode precursor material is expressed as Ni x Co y Mn z Al w (OH)2, where 0.80 < x < 0.90, 0.10 < y < 0.20, 0 ≤ z < 0.10, 0 ≤ w < 0.10, and x + y + z + w = 1.

8. A high nickel positive electrode material, characterized in that: The high-nickel positive electrode material is prepared by sintering a high-nickel positive electrode precursor material prepared by the method according to any one of claims 1 to 6 or a high-nickel positive electrode precursor material according to claim 7 with a lithium source.

9. A positive electrode sheet, characterized in that: The positive electrode active material in the positive electrode sheet includes the high-nickel positive electrode material as claimed in claim 8.

10. A secondary battery, characterized in that: The positive electrode in the secondary battery comprises the positive electrode sheet as claimed in claim 9.

Images