Ternary positive electrode active material, preparation method thereof and battery cell

Abstract

The invention provides a ternary positive electrode active material, a preparation method thereof and a battery cell, and belongs to the technical field of positive electrode active material manufacturing. The ternary positive electrode active material comprises a ternary material matrix and an oxide coating layer located on the surface of the ternary material matrix, in primary particles of the ternary positive electrode active material, the average long diameter is L [mu] m, the average short diameter is H [mu] m, the specific surface area of the ternary positive electrode active material is S m < 2 > / g, and the numerical values of L, H and S meet the condition that L / H * S0.5 is larger than or equal to 3 and smaller than or equal to 5, the ternary positive electrode active material can effectively improve the problems of poor lithium ion transmission performance and structural stability and the like of the ternary positive electrode material in the charging and discharging process, so that a corresponding battery has excellent electrical properties such as high capacity, high rate and long charging and discharging time.

Description

Technical Field

[0001] This application relates to the field of cathode active material manufacturing technology, and more specifically, to a ternary cathode active material, its preparation method, and a battery cell. Background Technology

[0002] Ternary cathode active materials have become one of the mainstream cathode active materials due to their high energy density. However, ternary cathode materials suffer from problems such as poor lithium-ion transport performance and structural stability during charge and discharge, which severely affects the electrical performance of the corresponding batteries. Currently, to solve these problems, researchers mainly use methods such as element doping and coating layers to modify the materials. However, the modification effect of existing technologies is not ideal, resulting in unsatisfactory electrical performance of the corresponding batteries. Summary of the Invention

[0003] The purpose of this application is to provide a ternary cathode active material, its preparation method, and a battery cell. The ternary cathode active material has a core-shell structure and satisfies 3≤L / H*S. 0.5 ≤5 can effectively improve the problems of poor lithium-ion transport performance and structural stability of ternary cathode materials during charging and discharging, thereby enabling the corresponding battery to have excellent electrical performance such as high capacity, high rate and long charge and discharge.

[0004] The embodiments of this application are implemented as follows: In a first aspect, embodiments of this application provide a ternary cathode active material, comprising a ternary material matrix and an oxide coating layer located on the surface of the ternary material matrix. The primary particles of the ternary cathode active material have an average major diameter of L μm, an average minor diameter of H μm, and a specific surface area of ​​S m². 2 / g, and the values ​​of L, H, and S satisfy: 3≤L / H*S 0.5 ≤5.

[0005] In the above technical solution, the ternary cathode active material has a core-shell structure and satisfies 3≤L / H*S 0.5 ≤5, on the one hand, ternary cathode active materials satisfy 3≤L / H*S 0.5 ≤5, where L / H mainly affects the lithium-ion transport performance of the material, and S mainly affects the lithium insertion / extraction efficiency and structural stability of the material. When the ternary cathode active material satisfies 3≤L / H*S 0.5With a pH ≤5, the material exhibits both superior lithium-ion transport performance and excellent structural stability. Furthermore, the ternary cathode active material comprises a ternary material matrix and an oxide coating layer on the surface of the matrix. The oxide coating layer provides the ternary cathode active material with a low surface alkalinity and effectively isolates it from the electrolyte. Simultaneously, the oxide coating layer helps mitigate the structural collapse issue caused by irreversible phase transitions during charge and discharge. Through the combined effect of these two aspects, the shortcomings in lithium-ion transport performance and structural stability of ternary cathode materials during charge and discharge are effectively improved, resulting in batteries with superior electrical performance, including high capacity, high rate capability, and long charge-discharge cycles.

[0006] In some alternative implementations, 1.9 ≤ L / H ≤ 2.3, or / and 3.5 m 2 / g≤S≤4.15 m 2 / g.

[0007] In the above technical solution, L / H (length-to-diameter ratio) is limited within the above range so that the material has a more suitable length-to-diameter ratio, thereby making the material have more ideal lithium-ion transport performance; S (specific surface area) is limited within the above range so that the material has a more suitable specific surface area, thereby making the material have more ideal lithium insertion / extraction efficiency and structural stability.

[0008] In some alternative implementations, 0.39 μm ≤ L ≤ 0.97 μm and 0.15 μm ≤ H ≤ 0.46 μm.

[0009] In the above technical solution, while satisfying a suitable aspect ratio, L and H are respectively limited within the above range so that the material has more suitable lithium-ion transport performance.

[0010] In some alternative implementations, the surface lithium content of the ternary cathode active material is ≤3000 ppm.

[0011] In the above technical solution, the ternary cathode active material has a low surface lithium content, which helps to reduce the probability of interfacial side reactions after it comes into contact with the electrolyte, thereby enabling the corresponding battery to have both excellent capacity and cycle performance.

[0012] In some alternative implementations, the ternary material matrix includes a ternary nickel-cobalt-manganese active material, and / or the oxide coating layer is made of a high-entropy oxide.

[0013] In the above technical solution, ternary nickel-cobalt-manganese active material is used as the material matrix, which enables the corresponding battery to have the advantages of high energy density and good adaptability to high voltage platforms. The oxide coating layer is made of high-entropy oxide. In addition to reducing the alkalinity of the material surface and isolating the electrolyte, the high-entropy oxide also makes it easier for the positive electrode active material to satisfy the condition: 3≤L / H*S because it contains multiple metal elements with different atomic radii located on the substrate surface. 0.5 ≤5, when the two are combined, the corresponding battery can have better cycle performance.

[0014] In some alternative implementations, the thickness of the oxide coating layer is 2.5 to 8.5 nm.

[0015] In the above technical solution, the thickness of the oxide coating layer is limited to the aforementioned range to ensure that the oxide coating layer has a suitable thickness. This allows for effective reduction of the material's alkalinity and isolation of the electrolyte while maintaining suitable lithium-ion transport performance. Furthermore, a suitable oxide coating layer thickness also makes it easier for the positive electrode active material to satisfy the condition: 3 ≤ L / H*S. 0.5 ≤5, which results in the corresponding battery having relatively excellent cycle performance.

[0016] In some alternative implementations, the high-entropy oxide is a perovskite-type high-entropy oxide.

[0017] In the above technical solution, a perovskite-type high-entropy oxide is used as the coating layer. This coating layer, in addition to reducing the surface alkalinity and isolating the electrolyte, also exhibits good compatibility with the ternary material matrix, allowing for a tight bond between the coating layer and the matrix. Furthermore, this coating layer possesses a wide range of oxygen octahedral lattice distortion, enabling the introduction of more oxygen vacancies to improve the charge-discharge performance of the corresponding battery. Moreover, using a perovskite-type high-entropy oxide as the coating layer also makes it easier for the positive electrode active material to satisfy the condition: 3 ≤ L / H*S. 0.5 ≤5.

[0018] In some alternative embodiments, the metal element in the high-entropy oxide is selected from at least five of the following: La, Al, Ni, Ca, Sr, Ti, Ba, Zr, Co, Mg, Ce, and Cr.

[0019] In the above technical solutions, there are many applicable types of metal elements in high-entropy oxides, which can provide more feasible implementation schemes, thereby facilitating the promotion and application of the technical solutions provided in the embodiments of this application; at the same time, limiting the applicable types of metal elements in high-entropy oxides to the above range can increase the cell volume and intergranular voids of the oxide coating material, and also help to improve the lithium-ion transport performance of the material, so that the corresponding battery has better rate performance.

[0020] In some optional implementations, in the ternary nickel-cobalt-manganese active material, the average valence state of the metal elements other than lithium is E1, and the average valence state of all metal elements in the high-entropy oxide is E2, with the absolute value of the difference between E1 and E2 not exceeding 0.46.

[0021] In the above technical solution, the absolute value of the difference between E1 and E2 is limited to the above range so that the average valence states of the transition metal elements in the material matrix and the metal elements in the coating layer are relatively close. This helps to improve the interface stability between the material matrix and the coating layer, the ion transport performance of lithium ions at the interface between the two, and effectively suppress the phase transition of the material matrix. As a result, the corresponding battery has better capacity, rate performance and cycle performance.

[0022] In some alternative implementations, 2.84 ≤ E1 ≤ 2.98, or / and 2.6 ≤ E2 ≤ 3.43.

[0023] In the above technical solution, limiting E1 within the aforementioned range ensures a relatively balanced overall valence state of the ternary material matrix, effectively suppressing phase transitions and resulting in superior structural stability. Simultaneously, it also allows the material to possess suitable electronic conductivity and lithium-ion transport performance, leading to better capacity, rate performance, and cycle performance in the corresponding battery. Limiting E2 within the aforementioned range ensures a suitable average valence state that facilitates lithium-ion transport within the coating layer. Furthermore, it helps suppress phase transitions and volume expansion of the material matrix during charging and discharging, while also providing superior thermal stability, further resulting in better capacity, rate performance, and cycle performance in the corresponding battery.

[0024] In some optional implementations, in the ternary nickel-cobalt-manganese active material, the ratio of the total molar amount of nickel, cobalt, and manganese to the molar amount of lithium is 1:(0.95~1.05).

[0025] In the above technical solution, the ratio of the total molar amount of nickel, cobalt and manganese to the molar amount of lithium in the ternary nickel-cobalt-manganese active material is limited to the above range so that the two have a more suitable molar ratio, thereby enabling the corresponding battery to have higher capacity and better cycle performance.

[0026] In some alternative embodiments, the molar ratio of nickel to the total molar ratio of nickel, cobalt, and manganese is (0.8~0.98):1, and the molar ratio of cobalt to the total molar ratio of nickel, cobalt, and manganese is (0.02~0.2):1.

[0027] In the above technical solution, limiting the molar ratio of nickel to the total molar ratio of nickel, cobalt, and manganese within the aforementioned range helps to improve the material's capacity while maintaining its structural stability; limiting the molar ratio of cobalt to the total molar ratio of nickel, cobalt, and manganese within the aforementioned range helps to improve the material's conductivity while also considering its manufacturing cost.

[0028] In some alternative embodiments, the ternary nickel-cobalt-manganese active material further includes a dopant element M, wherein the dopant element M is selected from at least one of W, Cr, Nb, Mo, Te, Sb and Zr.

[0029] In the above technical solution, the ternary nickel-cobalt-manganese active material also includes a doping element M and the types of doping elements are limited to the above range. The doping of the above elements can further improve the performance of the material (such as thermal stability, structural stability, etc.) so that the doped and modified material can be better applied under some extreme conditions.

[0030] In some alternative implementations, the molar ratio of the dopant element M to the total molar ratio of nickel, cobalt, and manganese is (0.002~0.05):1.

[0031] In the above technical solution, limiting the molar ratio of dopant element M to the total molar ratio of nickel, cobalt, and manganese within the aforementioned range allows for better modification without affecting the overall material properties. Furthermore, a suitable doping amount makes it easier for the positive electrode active material to satisfy the condition: 3 ≤ L / H*S. 0.5 ≤5.

[0032] Secondly, embodiments of this application provide a method for preparing a ternary cathode active material, comprising the following steps: mixing a ternary material matrix with raw materials for an oxide coating layer and then performing a first sintering treatment to form an oxide coating layer on the surface of the ternary material matrix, thereby obtaining a ternary cathode active material; wherein the average major diameter of the primary particles of the ternary cathode active material is L μm, the average minor diameter is H μm, and the specific surface area of ​​the ternary cathode active material is S m². 2 / g, and the values ​​of L, H, and S satisfy: 3≤L / H*S 0.5 ≤5.

[0033] Following the above process, a core-shell structure with the property 3 ≤ L / H*S can be obtained. 0.5 ≤5 can effectively improve the problems of poor lithium-ion transport performance and structural stability of ternary cathode materials during charging and discharging, thereby enabling the corresponding battery to have excellent electrical performance such as high capacity, high rate and long charge and discharge.

[0034] In some optional embodiments, the preparation method of the ternary material matrix includes the following steps: mixing a lithium source, a nickel source, a cobalt source, a manganese source and a dopant element M source and then performing a second sintering treatment, wherein the molar ratio of the dopant element M to the total molar ratio of nickel, cobalt and manganese is (0.002~0.05):1, to obtain a ternary material matrix precursor; and sequentially performing water washing, drying and reverse sintering treatments on the ternary material matrix precursor to obtain the ternary material matrix.

[0035] In the above technical solution, the raw materials contain not only lithium, nickel, cobalt, and manganese but also a dopant element M source, and the ratio of its molar amount to the total molar amount of nickel, cobalt, and manganese is limited to the aforementioned range. This ensures that the ternary material matrix prepared subsequently contains an appropriate amount of dopant element M, which helps improve various properties of the material (such as structural stability and thermal stability). The ternary material matrix precursor is sequentially subjected to water washing, drying, and reverse calcination treatments to ensure that the prepared ternary material matrix has advantages such as low surface alkalinity, smooth surface, and good structural stability. Furthermore, using the ternary material matrix prepared by the above process as the core also allows the subsequently prepared core-shell structured ternary cathode active material to satisfy 3 ≤ L / H*S. 0.5 ≤5, which enables the corresponding battery to have excellent electrical performance such as high capacity, high rate and long charge and discharge time.

[0036] In some alternative embodiments, the sintering step is performed at a temperature of 700-1100°C for 10-24 h; or / and the water washing step is performed at a temperature of 70-100°C, a solid-liquid ratio of 1 g:(1-3) mL, and a water washing time of 30-60 s; or / and the reverse sintering step is performed at a temperature of 400-600°C for 3-10 h.

[0037] In the above technical solution, by limiting the processing temperature and time in the sintering step to the above ranges, a high-quality ternary material matrix with good structural integrity and good doping uniformity can be prepared; by limiting the temperature, solid-liquid ratio and water washing time in the water washing step to the above ranges, a ternary material matrix with lower surface alkali content and smoother surface can be prepared; the reverse sintering treatment is carried out under the above conditions, which can effectively repair the lattice defects caused in the early high-temperature sintering process and help improve the structural stability of the material.

[0038] In some alternative embodiments, the step of sintering the mixture of the ternary material matrix and the raw materials for the oxide coating includes: The raw materials of the ternary material matrix and the oxide coating layer are mixed, wherein the mass ratio of the ternary material matrix to the raw materials is 100:(2~6) to obtain a mixture; the mixture is sintered at 300~700℃ to obtain a ternary positive electrode active material.

[0039] In the above technical solution, the mass ratio of the ternary material matrix to the raw materials is limited to the aforementioned range, so that the prepared ternary cathode active material has an oxide coating layer of suitable thickness. This allows the oxide coating layer to effectively reduce the alkalinity of the material and isolate the electrolyte while also possessing suitable lithium-ion transport performance. Limiting the sintering temperature to the aforementioned range enables the formation of an oxide coating layer with good integrity and suitable density on the surface of the ternary material matrix. Simultaneously, during the formation of the oxide coating layer on the surface of the ternary material matrix, the aforementioned temperature allows the grain size and density of the ternary material matrix to be maintained within a suitable range, resulting in suitable lithium-ion transport performance and structural stability. Furthermore, the step of mixing the ternary material matrix and the raw materials for the oxide coating layer and then performing sintering according to the above process ensures that the subsequently prepared core-shell structured ternary cathode active material satisfies 3≤L / H*S. 0.5 ≤5, which enables the corresponding battery to have excellent electrical performance such as high capacity, high rate and long charge and discharge time.

[0040] In some alternative implementations, the heat preservation sintering step takes 5 to 15 hours.

[0041] In the above technical solution, limiting the temperature in the heat preservation sintering step to the above range can form an oxide coating layer with good coating integrity and suitable density on the surface of the ternary material matrix. At the same time, during the process of forming the oxide coating layer on the surface of the ternary material matrix, the above time can maintain the grain size and density of the ternary material matrix within a suitable range, so that it has suitable lithium-ion transport performance and structural stability.

[0042] Thirdly, embodiments of this application provide a battery cell, which includes a ternary positive electrode active material as provided in the first aspect embodiment or a ternary positive electrode active material prepared by the preparation method provided in the second aspect embodiment.

[0043] In the above technical solution, the ternary cathode active material in the battery cell has a core-shell structure and satisfies 3≤L / H*S 0.5 ≤5 can effectively improve the problems of poor lithium-ion transport performance and structural stability of ternary cathode materials during charging and discharging, thereby enabling the corresponding battery to have excellent electrical performance such as high capacity, high rate and long charge and discharge. Attached Figure Description

[0044] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 A process flow diagram of a method for preparing a ternary cathode active material provided in an embodiment of this application; Figure 2 This is a SEM image of the ternary cathode active material prepared in Example 1 of this application; Figure 3 This is a SEM image of the ternary cathode active material prepared in Comparative Example 2 of this application; Figure 4 This is a SEM image of the ternary cathode active material prepared in Comparative Example 3 of this application; Figure 5 This is a cross-sectional view of the ternary positive electrode active material prepared in Example 1 of this application; Figure 6 This is the EDS image of the ternary cathode active material prepared in Example 1 of this application; Figure 7 XRD comparison images of a series of ternary cathode active materials provided for this application; Figure 8 This is a TEM image of the ternary positive electrode active material prepared in Example 1 of this application; Figure 9 A comparison chart of the cycle performance of a series of battery samples provided for this application. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0047] It should be noted that the terms "and / or" in this application, such as "feature 1 and / or feature 2", all refer to the three cases of "feature 1" alone, "feature 2" alone, and "feature 1" plus "feature 2".

[0048] In addition, in the description of this application, unless otherwise stated, "one or more" means two or more; the range of "numerical value a to numerical value b" includes the two endpoints "a" and "b"; and "unit of measurement" in "numerical value a to numerical value b + unit of measurement" represents the "unit of measurement" of both "numerical value a" and "numerical value b".

[0049] The following is a detailed description of a ternary cathode active material, its preparation method, and its battery cell according to embodiments of this application.

[0050] In a first aspect, embodiments of this application provide a ternary cathode active material, comprising a ternary material matrix and an oxide coating layer located on the surface of the ternary material matrix. The primary particles of the ternary cathode active material have an average major diameter of L μm, an average minor diameter of H μm, and a specific surface area of ​​S m². 2 / g, and the values ​​of L, H, and S satisfy: 3≤L / H*S 0.5 ≤5, for example, but not limited to, a range of values ​​between any one or any two of 3, 3.2, 3.4, 3.6, 3.8, 4, 4.2, 4.4, 4.6, 4.8 and 5.

[0051] It should be noted that the major axis is the maximum distance of a primary particle under its projection without considering its direction, and the minor axis is the minimum distance in the direction orthogonal to the major axis. Correspondingly, the average major axis is the ratio of the sum of the major axes of multiple primary particles to the number of primary particles, and the average minor axis is the ratio of the sum of the minor axes of multiple primary particles to the number of primary particles.

[0052] In this application, the ternary cathode active material has a core-shell structure and satisfies 3≤L / H*S 0.5 ≤5, on the one hand, ternary cathode active materials satisfy 3≤L / H*S 0.5 ≤5, where L / H (aspect ratio) mainly affects the lithium-ion transport performance of the material (a suitable L / H promotes lithium-ion transport), and S (specific surface area) mainly affects the lithium insertion / extraction efficiency and structural stability of the material (a suitable S provides a suitable number of active reaction sites, which helps the material to perform lithium insertion / extraction; at the same time, a suitable S can also reduce the probability of interfacial side reactions, thereby improving the structural stability of the material). When the ternary cathode active material satisfies 3≤L / H*S 0.5With a pH ≤5, the material exhibits both superior lithium-ion transport performance and excellent structural stability. Furthermore, the ternary cathode active material comprises a ternary material matrix and an oxide coating layer on the surface of the matrix. The oxide coating layer provides the ternary cathode active material with a low surface alkalinity and effectively isolates it from the electrolyte (low alkalinity and electrolyte isolation effectively suppress interfacial side reactions, thus mitigating issues such as increased impedance and structural damage caused by interfacial side reactions). Simultaneously, the oxide coating layer also helps mitigate the structural collapse caused by irreversible phase transitions during charge and discharge. Through the combined effect of these two aspects, the poor lithium-ion transport performance and structural stability of ternary cathode materials during charge and discharge are effectively improved, resulting in batteries with superior electrical performance including high capacity, high rate capability, and long charge-discharge cycles.

[0053] As an example, 1.9 ≤ L / H ≤ 2.3, for example, but not limited to, L / H being any point value of 1.9, 2.0, 2.1, 2.2, and 2.3, or a range value between any two.

[0054] In this embodiment, the L / H ratio is limited to the above range so that the material has a more suitable aspect ratio, thereby giving the material more ideal lithium-ion transport performance.

[0055] As an example, 3.5 m 2 / g≤S≤4.15 m 2 / g, for example, but not limited to, S = 3.5 m 2 / g, 3.6 m 2 / g, 3.7 m 2 / g、3.8 m 2 / g、3.9 m 2 / g, 4.0 m 2 / g、4.1 m 2 / g and 4.15 m 2 Any point value in / g or any range value between the two.

[0056] In this embodiment, S is limited to the above range so that the material has a more suitable specific surface area, thereby making the material have a more ideal lithium insertion / extraction efficiency and structural stability.

[0057] As an example, 0.39 μm ≤ L ≤ 0.97 μm, for example, but not limited to, L being any one of the values ​​of 0.39 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, and 0.97 μm or any range between two of them; 0.15 μm ≤ H ≤ 0.46 μm, for example, but not limited to, H being any one of the values ​​of 0.15 μm, 0.2 μm, 0.3 μm, 0.4 μm, and 0.46 μm or any range between two of them.

[0058] In this embodiment, while satisfying a suitable aspect ratio, L and H are respectively limited within the above-mentioned ranges so that the material has more suitable lithium-ion transport performance.

[0059] As an example, the surface lithium content of ternary cathode active materials is ≤3000 ppm.

[0060] In this embodiment, the ternary cathode active material has a low surface lithium content, which helps to reduce the probability of interfacial side reactions after it comes into contact with the electrolyte, thereby enabling the corresponding battery to have both excellent capacity and cycle performance.

[0061] It should be noted that the material of the ternary material matrix is ​​not limited and can be selected and set in accordance with the conventional methods in this field.

[0062] As an example, the ternary material matrix includes ternary nickel-cobalt-manganese active materials.

[0063] In this embodiment, a ternary nickel-cobalt-manganese active material is used as the material matrix, so that the corresponding battery has the advantages of high energy density and good adaptability to high voltage platforms.

[0064] It should be noted that the material of the oxide coating layer is not limited and can be selected and set in accordance with the conventional methods in this field.

[0065] As an example, the oxide coating material includes high-entropy oxides.

[0066] In this embodiment, the oxide coating layer is made of a high-entropy oxide. Besides reducing the alkalinity of the material surface and isolating the electrolyte, this coating layer, because it contains multiple metal elements with different atomic radii located on the substrate surface, makes it easier for the positive electrode active material to satisfy the condition: 3 ≤ L / H*S. 0.5 ≤5, when the two are combined, the corresponding battery can have better cycle performance.

[0067] As an example, the thickness of the oxide coating is 2.5~8.5 nm.

[0068] In this embodiment, the thickness of the oxide coating layer is limited to the aforementioned range to ensure that the oxide coating layer has a suitable thickness. This allows for effective reduction of the material's alkalinity and isolation of the electrolyte while maintaining suitable lithium-ion transport performance. Furthermore, a suitable oxide coating layer thickness also makes it easier for the positive electrode active material to satisfy the condition: 3 ≤ L / H*S. 0.5 ≤5, which results in the corresponding battery having relatively excellent cycle performance.

[0069] As an example, high-entropy oxides are perovskite-type high-entropy oxides.

[0070] In this embodiment, a perovskite-type high-entropy oxide is used as the coating layer. Besides reducing the surface alkalinity and isolating the electrolyte, this coating layer also exhibits good compatibility with the ternary material matrix, allowing for a tight bond between the coating layer and the matrix. Furthermore, this coating layer possesses a wide range of oxygen octahedral lattice distortion, enabling the introduction of more oxygen vacancies to improve the charge-discharge performance of the corresponding battery. In addition, using a perovskite-type high-entropy oxide as the coating layer makes it easier for the positive electrode active material to satisfy the condition: 3 ≤ L / H*S. 0.5 ≤5.

[0071] As an example, the metal element in the high-entropy oxide is selected from at least five of the following: La, Al, Ni, Ca, Sr, Ti, Ba, Zr, Co, Mg, Ce, and Cr.

[0072] In this embodiment, the applicable types of metal elements in high-entropy oxides are numerous, providing a wide range of feasible implementation schemes, thereby facilitating the promotion and application of the technical solutions provided in this application. At the same time, limiting the applicable types of metal elements in high-entropy oxides to the above-mentioned range can increase the cell volume and intergranular voids of the oxide coating material, which also helps to improve the lithium-ion transport performance of the material, so that the corresponding battery has superior rate performance.

[0073] It should be noted that the molar ratio of various elements in high-entropy oxides is not limited and can be adjusted adaptively according to actual needs. For example, a high-entropy oxide may contain 5 metal elements, and the molar ratio of the 5 metal elements may be (0.2~0.5): (0.2~0.5): (0.2~0.5): (0.2~0.5): (0.2~0.5). The specific molar ratio can be adjusted adaptively within this range.

[0074] As an example, in ternary nickel-cobalt-manganese active materials, the average valence state of metal elements other than lithium is E1, and the average valence state of all metal elements in high-entropy oxides is E2. The absolute value of the difference between E1 and E2 is no greater than 0.46.

[0075] In this embodiment, the absolute value of the difference between E1 and E2 is limited to the above range so that the average valence states of the transition metal elements in the material matrix and the metal elements in the coating layer are relatively close. This helps to improve the interface stability between the material matrix and the coating layer, the ion transport performance of lithium ions at the interface between the two, and effectively suppress the phase transition of the material matrix. As a result, the corresponding battery has better capacity, rate performance and cycle performance.

[0076] To help understand the meaning of average valence state, specific examples are provided here, such as the chemical formula of a ternary material matrix, Li. a1 Ni x Co y Mn z M b1 O2, then E1 = (4-a1) / (x+y+z+b1); For example, the chemical formula of a high-entropy oxide is A. a2 B b2 C c D d E e O3, then E2 = 6 / (a2+b2+c+d+e).

[0077] As an example, 2.84 ≤ E1 ≤ 2.98, for example, but not limited to, E1 being any point value or a range value between any two of 2.84, 2.86, 2.88, 2.9, 2.91, 2.92, 2.93, 2.94, 2.95, 2.96, 2.97, and 2.98.

[0078] In this embodiment, E1 is limited to the above range so that the overall valence state of the ternary material matrix is ​​more balanced, which can effectively suppress phase transitions and thus make the material have better structural stability. At the same time, it can also make the material have more suitable electronic conductivity and lithium-ion transport performance, thereby making the corresponding battery have better capacity, rate performance and cycle performance.

[0079] As an example, 2.6 ≤ E2 ≤ 3.43, for example, but not limited to, E2 being any point value of 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, and 3.43, or a range value between any two.

[0080] In this embodiment, limiting E2 to the above-mentioned range, a suitable average valence state helps lithium ions to be transported in the coating layer. At the same time, it also helps to suppress phase transitions and volume expansion of the material matrix during charging and discharging. In addition, it can also make the material have better thermal stability, thereby enabling the corresponding battery to have better capacity, rate performance and cycle performance.

[0081] As an example, in a ternary nickel-cobalt-manganese active material, the ratio of the total molar amount of nickel, cobalt, and manganese to the molar amount of lithium is 1:(0.95~1.05), for example, but not limited to any one of the molar ratios of 1:0.95, 1:0.96, 1:0.97, 1:0.98, 1:0.99, 1:1.0, 1:1.01, 1:1.02, 1:1.03, 1:1.04, and 1:1.05, or any range between the two.

[0082] In this embodiment, the ratio of the total molar amount of nickel, cobalt, and manganese in the ternary nickel-cobalt-manganese active material to the molar amount of lithium is limited to the above-mentioned range so that the two have a more suitable molar ratio, thereby enabling the corresponding battery to have higher capacity and better cycle performance.

[0083] As an example, the molar ratio of nickel to the total molar ratio of nickel, cobalt, and manganese is (0.8~0.98):1, for example, but not limited to any one of the following molar ratios or any range between two: 0.8:1, 0.82:1, 0.84:1, 0.86:1, 0.88:1, 0.9:1, 0.92:1, 0.94:1, 0.96:1, and 0.98:1.

[0084] In this embodiment, limiting the ratio of the molar amount of nickel to the total molar amount of nickel, cobalt, and manganese within the aforementioned range helps to improve the material's capacity while maintaining its structural stability.

[0085] As an example, the molar ratio of cobalt to the total molar ratio of nickel, cobalt, and manganese is (0.02~0.2):1, for example, but not limited to any one of the following molar ratios or any range between two: 0.02:1, 0.025:1, 0.05:1, 0.075:1, 0.1:1, 0.125:1, 0.15:1, 0.175:1, and 0.2:1.

[0086] In this embodiment, limiting the molar ratio of cobalt to the total molar ratio of nickel, cobalt, and manganese within the aforementioned range helps to improve the material's conductivity while also taking into account the material's manufacturing cost.

[0087] It should be noted that when the molar amount of nickel is K1 and the total molar amount of nickel, cobalt and manganese is K2, K1+K2<1 must be satisfied. Then 1-K1-K2 is the molar amount of manganese and the total molar amount of nickel, cobalt and manganese.

[0088] As an example, the ternary nickel-cobalt-manganese active material also includes a dopant element M, wherein the dopant element M is selected from at least one of W, Cr, Nb, Mo, Te, Sb and Zr.

[0089] In this embodiment, the ternary nickel-cobalt-manganese active material also includes a doping element M and the types of doping elements are limited to the above-mentioned range. The doping of the above-mentioned elements can further improve the performance of the material (such as thermal stability, structural stability, etc.) so that the doped and modified material can be better applied under some extreme conditions.

[0090] As an example, the molar ratio of the dopant element M to the total molar ratio of nickel, cobalt, and manganese is (0.002~0.05):1, for example, but not limited to any one of the molar ratios of 0.002:1, 0.005:1, 0.01:1, 0.02:1, 0.03:1, 0.04:1, and 0.05:1, or any range between the two.

[0091] In this embodiment, limiting the molar ratio of dopant element M to the total molar ratio of nickel, cobalt, and manganese within the aforementioned range allows for effective modification without affecting the overall material properties. Furthermore, a suitable doping amount makes it easier for the positive electrode active material to satisfy the condition: 3 ≤ L / H*S. 0.5 ≤5.

[0092] Secondly, embodiments of this application provide a method for preparing a ternary cathode active material, comprising the following steps: mixing a ternary material matrix with raw materials for an oxide coating layer and then performing a first sintering treatment to form an oxide coating layer on the surface of the ternary material matrix, thereby obtaining a ternary cathode active material; wherein the average major diameter of the primary particles of the ternary cathode active material is L μm, the average minor diameter is H μm, and the specific surface area of ​​the ternary cathode active material is S m². 2 / g, and the values ​​of L, H, and S satisfy: 3≤L / H*S 0.5 ≤5.

[0093] In this application, by preparing the material according to the above process, a ternary positive electrode active material with a core-shell structure can be obtained, and it satisfies 3≤L / H*S. 0.5 ≤5 can effectively improve the problems of poor lithium-ion transport performance and structural stability of ternary cathode materials during charging and discharging, thereby enabling the corresponding battery to have excellent electrical performance such as high capacity, high rate and long charge and discharge.

[0094] It should be noted that the type of ternary material matrix is ​​not limited and can be set according to conventional choices in the field. For example, the ternary material matrix can be a doped ternary nickel-cobalt-manganese cathode material or an undoped ternary nickel-cobalt-manganese cathode material. In the embodiments of this application, a doped ternary nickel-cobalt-manganese is used as an example, and the following is an auxiliary explanation in conjunction with a specific preparation process.

[0095] As an example, the preparation method of the ternary material matrix includes the following steps: mixing a lithium source, a nickel source, a cobalt source, a manganese source and a dopant element M source and then performing a second sintering treatment, wherein the molar ratio of the dopant element M to the total molar ratio of nickel, cobalt and manganese is (0.002~0.05):1 (for example, but not limited to any one of the molar ratios of 0.002:1, 0.005:1, 0.01:1, 0.02:1, 0.03:1, 0.04:1 and 0.05:1 or any range between two), to obtain a ternary material matrix precursor; and sequentially performing a water washing treatment, a drying treatment and a reverse sintering treatment on the ternary material matrix precursor to obtain the ternary material matrix.

[0096] In this embodiment, the raw material contains a dopant element M in addition to lithium, nickel, cobalt, and manganese, and the ratio of its molar amount to the total molar amount of nickel, cobalt, and manganese is limited to the aforementioned range. This ensures that the ternary material matrix prepared subsequently contains an appropriate amount of dopant element M, which helps improve various properties of the material (such as structural stability and thermal stability). The ternary material matrix precursor is sequentially subjected to water washing, drying, and reverse calcination treatments to ensure that the prepared ternary material matrix has advantages such as low surface alkalinity, smooth surface, and good structural stability. Furthermore, using the ternary material matrix prepared by the above process as the core also allows the subsequently prepared core-shell structured ternary cathode active material to satisfy 3 ≤ L / H*S. 0.5 ≤5, which enables the corresponding battery to have excellent electrical performance such as high capacity, high rate and long charge and discharge time.

[0097] As an example, the step of mixing a lithium source, a nickel source, a cobalt source, a manganese source and a dopant element M source and then performing a second sintering process includes: mixing a lithium source, a nickel-cobalt-manganese precursor and a dopant element M source to obtain a mixture; and then performing a sintering process on the mixture.

[0098] In this embodiment, the nickel source, cobalt source, and manganese source are all provided by a single raw material, nickel-cobalt-manganese precursor, which has the advantages of a relatively simple raw material system and simple and easy mixing process.

[0099] It should be noted that the type of nickel-cobalt-manganese precursor is not limited, and it can be at least one of nickel-cobalt-manganese oxide, nickel-cobalt-manganese carbonate, nickel-cobalt-manganese hydroxide, and nickel-cobalt-manganese oxalate.

[0100] It should be noted that the type of lithium source is not limited, and it can be at least one of lithium carbonate, lithium hydroxide, lithium nitrate, lithium sulfate, lithium chloride and lithium fluoride.

[0101] It should be noted that the type of dopant element M is not limited. For example, dopant element M can be selected from at least one of W, Cr, Nb, Mo, Te, Sb and Zr.

[0102] It should be noted that the molar percentage of various metal elements in the mixture is not limited and can be adjusted according to actual needs.

[0103] As an example, in the mixture, the ratio of the total molar amount of nickel, cobalt, and manganese to the molar amount of lithium is 1:(0.95~1.05), for example, but not limited to any one of the molar ratios of 1:0.95, 1:0.96, 1:0.97, 1:0.98, 1:0.99, 1:1.0, 1:1.01, 1:1.02, 1:1.03, 1:1.04, and 1:1.05, or any range between the two.

[0104] In this embodiment, the ratio of the total molar amount of nickel, cobalt, and manganese in the mixture to the molar amount of lithium is limited to the above-mentioned range, so that the prepared ternary material matrix has a relatively appropriate amount of lithium and nickel, cobalt, and manganese, thereby enabling the corresponding battery to have higher capacity and better cycle performance.

[0105] As an example, in the mixture, the molar ratio of nickel to the total molar ratio of nickel, cobalt, and manganese is (0.8~0.98):1, for example, but not limited to any one of the molar ratios of 0.8:1, 0.82:1, 0.84:1, 0.86:1, 0.88:1, 0.9:1, 0.92:1, 0.94:1, 0.96:1, and 0.98:1, or any range between two of them.

[0106] In this embodiment, the ratio of the molar amount of nickel to the total molar amount of nickel, cobalt, and manganese in the mixture is limited to the above-mentioned range, so that the prepared ternary material matrix has a relatively appropriate amount of nickel, which helps to improve the material capacity while taking into account the structural stability of the material.

[0107] As an example, in the mixture, the molar ratio of cobalt to the total molar ratio of nickel, cobalt, and manganese is (0.02~0.2):1, for example, but not limited to any one of the following molar ratios or a range between any two: 0.02:1, 0.025:1, 0.05:1, 0.075:1, 0.1:1, 0.125:1, 0.15:1, 0.175:1, and 0.2:1.

[0108] In this embodiment, the ratio of the molar amount of cobalt to the total molar amount of nickel, cobalt, and manganese in the mixture is limited to the above-mentioned range, so that the prepared ternary material matrix has a relatively appropriate amount of cobalt, which helps to improve the conductivity of the material while taking into account the manufacturing cost of the material.

[0109] It should be noted that when the molar amount of nickel is K1 and the total molar amount of nickel, cobalt and manganese is K2, K1+K2<1 must be satisfied. Then 1-K1-K2 is the molar amount of manganese and the total molar amount of nickel, cobalt and manganese.

[0110] As an example, in the formed ternary material matrix, the average valence state of the metal elements other than lithium is E1 and satisfies 2.9≤E1≤3.0.

[0111] In this embodiment, when the prepared ternary material matrix satisfies 2.9≤E1≤3.0, phase transition can be effectively suppressed, thereby giving the material superior structural stability. At the same time, the material also has suitable electronic conductivity and lithium-ion transport performance, thus enabling the corresponding battery to have superior capacity, rate performance and cycle performance.

[0112] It should be noted that the sintering parameters of the ternary material matrix are not limited and can be carried out according to conventional processes in this field.

[0113] As an example, in the sintering process, the processing temperature is 700~1100℃, for example, but not limited to any one of 700℃, 800℃, 900℃, 1000℃ and 1100℃ or any range between two; the processing time is 10~24 h, for example, but not limited to any one of 10 h, 12 h, 14 h, 16 h, 18 h, 20 h, 22 h and 24 h or any range between two.

[0114] In this embodiment, by limiting the processing temperature and time in the sintering process to the above-mentioned ranges, a high-quality ternary material matrix with good structural integrity and good doping uniformity can be prepared.

[0115] It should be noted that before the sintering temperature reaches the preset temperature, there is also a heating stage. The heating rate of the heating stage is not limited and can be carried out in accordance with conventional processes in this field. For example, the heating rate is 2~10℃ / min, such as, but not limited to, any one of the heating rates of 2℃ / min, 4℃ / min, 6℃ / min, 8℃ / min and 10℃ / min or any range between two of them.

[0116] As an example, in the water washing step, the treatment temperature is 70~100℃, for example, but not limited to any one of 70℃, 80℃, 90℃ and 100℃ or any range between two; the solid-liquid ratio is 1 g: (1~3) mL, for example, but not limited to any one of 1 g: 1 mL, 1 g: 1.5 mL, 1 g: 2 mL, 1 g: 2.5 mL and 1 g: 3 mL or any range between two; the water washing time is 30~60 s, for example, but not limited to any one of 30 s, 40 s, 50 s and 60 s or any range between two.

[0117] In this embodiment, by limiting the temperature, solid-liquid ratio, and washing time in the water washing process to the above-mentioned ranges, a ternary material matrix with lower surface alkali content and smoother surface can be prepared.

[0118] As an example, in the drying process, the drying method is vacuum drying, and the drying temperature is 80~120℃, for example, but not limited to any one of 80℃, 90℃, 100℃, 110℃ and 120℃ or any range between two; the drying time is 18~24 h, for example, but not limited to any one of 18 h, 19 h, 20 h, 21 h, 22 h, 23 h and 24 h or any range between two.

[0119] In this embodiment, by using the above-described drying method and conditions, moisture can be effectively removed while maintaining the cleanliness of the ternary material matrix.

[0120] As an example, the backburning process is carried out in an inert atmosphere (e.g., nitrogen or argon) at a temperature of 400–600°C, for example, but not limited to any one of 400°C, 450°C, 500°C, 550°C, and 600°C, or a range between any two; and for a processing time of 3–10 h, for example, but not limited to any one of 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, and 10 h, or a range between any two.

[0121] In this embodiment, the reverse sintering process is carried out under the above conditions, which can effectively repair the lattice defects caused in the early high-temperature sintering process and help improve the structural stability of the material.

[0122] It should be noted that before the back-burning temperature reaches the preset temperature, there is also a heating stage. The heating rate of the heating stage is not limited and can be carried out in accordance with conventional processes in this field. For example, the heating rate is 1~5℃ / min, such as, but not limited to, any one of the heating rates of 1℃ / min, 2℃ / min, 3℃ / min, 4℃ / min and 5℃ / min or any range between two of them.

[0123] As an example, the step of mixing the raw materials of the ternary material matrix and the oxide coating layer and then performing a first sintering treatment includes: mixing the raw materials of the ternary material matrix and the oxide coating layer, wherein the mass ratio of the ternary material matrix to the raw materials is 100:(2~6) (e.g., but not limited to any one of the mass ratios of 100:2, 100:3, 100:4, 100:5 and 100:6 or any range between the two), to obtain a mixture; and sintering the mixture at 300~700℃ (e.g., but not limited to any one of the mass values ​​of 300℃, 400℃, 500℃, 600℃ and 700℃ or any range between the two) to obtain a ternary positive electrode active material.

[0124] In this embodiment, the mass ratio of the ternary material matrix to the raw materials is limited to the aforementioned range, so that the prepared ternary cathode active material has an oxide coating layer of suitable thickness. This allows the oxide coating layer to effectively reduce the alkalinity of the material and isolate the electrolyte while also exhibiting suitable lithium-ion transport performance. Limiting the sintering temperature to the aforementioned range enables the formation of an oxide coating layer with good integrity and suitable density on the surface of the ternary material matrix. Simultaneously, during the formation of the oxide coating layer on the surface of the ternary material matrix, the aforementioned temperature maintains the grain size and density of the ternary material matrix within a suitable range, resulting in suitable lithium-ion transport performance and structural stability. Furthermore, the step of mixing the ternary material matrix and the raw materials for the oxide coating layer and then sintering them according to the aforementioned process ensures that the subsequently prepared core-shell structured ternary cathode active material satisfies 3≤L / H*S. 0.5 ≤5, which enables the corresponding battery to have excellent electrical performance such as high capacity, high rate and long charge and discharge time.

[0125] As an example, in the heat preservation sintering step, the processing time is 5 to 15 hours, for example, but not limited to any one of the following processing times: 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, and 15 hours, or any range between two of them.

[0126] In this embodiment, limiting the temperature in the heat preservation sintering step to the above-mentioned range enables the formation of an oxide coating layer with good coating integrity and suitable density on the surface of the ternary material substrate. At the same time, during the formation of the oxide coating layer on the surface of the ternary material substrate, the above-mentioned time allows the grain size and density of the ternary material substrate to be maintained within a suitable range, so that it has suitable lithium-ion transport performance and structural stability.

[0127] It should be noted that before the sintering temperature reaches the preset temperature, there is a heating stage. The heating rate during the heating stage is not limited and can be carried out according to conventional processes in this field. For example, the heating rate is 1~10℃ / min, such as, but not limited to, any one of the heating rates of 1℃ / min, 2℃ / min, 4℃ / min, 6℃ / min, 8℃ / min and 10℃ / min or any range between two of them.

[0128] As an example, the raw material of the oxide coating contains at least five metals, and the metal elements are selected from at least five of La, Al, Ni, Ca, Sr, Ti, Ba, Zr, Co, Mg, Ce and Cr.

[0129] In this embodiment, the oxide coating layer formed by the raw material is a high-entropy oxide coating layer. In addition to reducing the alkalinity of the material surface and isolating the electrolyte, the coating layer of this material can also achieve extensive tuning of the material structure and performance because it contains a variety of metal elements with different atomic radii, thereby enabling the corresponding battery to have better cycle performance.

[0130] It should be noted that the molar percentage of various elements in the raw materials is not limited and can be adjusted according to actual needs.

[0131] As an example, the raw material contains five metallic elements, and the molar ratio of the five metallic elements is (0.2~0.5): (0.2~0.5): (0.2~0.5): (0.2~0.5): (0.2~0.5): (0.2~0.5).

[0132] In this embodiment, once the types of metal elements are determined, they are configured according to the aforementioned molar ratio. This allows the high-entropy oxide coating layer formed from the raw materials to be a perovskite-type high-entropy oxide coating layer. This coating layer, in addition to reducing the surface alkalinity of the material and isolating the electrolyte, also exhibits good compatibility with the ternary material matrix, enabling a tight bond between the coating layer and the matrix. Furthermore, this coating layer possesses a wide range of oxygen octahedral lattice distortion, introducing more oxygen vacancies to improve the charge-discharge performance of the corresponding battery. Moreover, using a perovskite-type high-entropy oxide as the coating layer makes it easier for the positive electrode active material to satisfy the condition: 3 ≤ L / H*S. 0.5≤5.

[0133] It should be noted that the raw material type of the oxide coating layer is not limited. For example, it can be at least one of the oxides and salts (such as the corresponding sulfates, phosphates, etc.) of the corresponding metal elements.

[0134] It should be noted that when the raw material for the oxide coating layer is a salt of the corresponding metal element, after the first sintering treatment, the material is also washed and dried to effectively remove impurities corresponding to various acid radicals.

[0135] As an example, the formed oxide coating is a high-entropy oxide coating, and the average valence state of all metal elements in the high-entropy oxide coating is E2 and satisfies 2.6≤E2≤3.3.

[0136] In this embodiment, when the formed high-entropy oxide satisfies 2.6≤E2≤3.3, it helps lithium ions to be transported in the coating layer. At the same time, it also helps to suppress phase transitions and volume expansion of the material matrix during charging and discharging. In addition, it can also make the material have better thermal stability, thereby enabling the corresponding battery to have better capacity, rate performance and cycle performance.

[0137] It should be noted that when the prepared ternary material matrix satisfies 2.9≤E1≤3.0 and the formed high-entropy oxide coating layer satisfies 2.6≤E2≤3.3, the final prepared ternary cathode active material has the characteristic that the average valence states of the transition metal elements in the material matrix and the metal elements in the coating layer are relatively close. This helps to improve the interfacial stability between the material matrix and the coating layer, the ion transport performance of lithium ions at the interface between the two, and effectively suppress the phase transition of the material matrix. As a result, the corresponding battery has better capacity, rate performance and cycle performance.

[0138] It should be noted that, in order to ensure that the formed oxide coating layer is a high-entropy oxide coating layer and satisfies 2.6≤E2≤3.3, the specific implementation method is not limited. The types of metal elements in the raw materials of the oxide coating layer and the molar ratio between different metal elements can be flexibly adjusted according to actual needs. For example, the raw material composition of the oxide coating layer is: LaAlO3, BaZrO3 and TiO2, wherein the molar ratio of La, Al, Ba, Ti and Zr in the raw materials is 1:1:1:1:1.5 respectively.

[0139] It should be noted that, through the integration of the preparation process, it is known that in order to ensure that the prepared ternary cathode active material has a core-shell structure and that its corresponding primary particles satisfy 3≤L / H*S 0.5 ≤5, the preparation process must be strictly carried out according to the following steps: A lithium source, nickel source, cobalt source, manganese source, and dopant element M source are mixed and subjected to a second sintering treatment. The molar ratio of dopant element M to the total molar ratio of nickel, cobalt, and manganese is (0.002~0.05):1, yielding a ternary material matrix precursor. The ternary material matrix precursor is then subjected to water washing, drying, and reverse sintering treatments to obtain the ternary material matrix. The ternary material matrix and the raw materials for the oxide coating layer are then mixed, with a mass ratio of ternary material matrix to raw materials of 100:(2~6), yielding a mixture. The mixture is then sintered at 300~700℃ to obtain the ternary cathode active material.

[0140] It should be noted that, unless otherwise specified or limited, the processes or steps in the preparation of ternary cathode active materials can be set according to conventional methods in the field. As an example, a process flow diagram for the preparation method of ternary cathode active materials is exemplarily provided below. Figure 1 .

[0141] Thirdly, embodiments of this application provide a battery cell, which includes a ternary positive electrode active material as provided in the first aspect embodiment or a ternary positive electrode active material prepared by the preparation method provided in the second aspect embodiment.

[0142] In this application, the ternary cathode active material in the battery cell has a core-shell structure and its corresponding primary particles satisfy 3≤L / H*S 0.5 ≤5 can effectively improve the problems of poor lithium-ion transport performance and structural stability of ternary cathode materials during charging and discharging, thereby enabling the corresponding battery to have excellent electrical performance such as high capacity, high rate and long charge and discharge.

[0143] The features and performance of this application will be further described in detail below with reference to the embodiments.

[0144] Example 1 This application provides a method for preparing a ternary cathode active material, including the following steps: 1 mol of nickel-cobalt-manganese precursor (nickel-cobalt-manganese hydroxide Ni) 0.93 Co 0.06 Mn 0.01A mixture of 1.04 mol LiOH·H2O, 0.002 mol WO3, and 0.001 mol Cr2O3 was prepared by uniformly mixing. The mixture was then placed in an atmosphere-controlled furnace and sintered at 900℃ for 15 hours at a rate of 2℃ / min under air atmosphere. After cooling, the mixture was crushed and sieved to obtain a ternary material matrix precursor. Deionized water was then heated and maintained at 90℃, with a solid-liquid ratio (g / mL) of 1:2. The ternary material matrix precursor was added to the water and stirred for 40 seconds for rapid scalding. After scalding, the solid-liquid mixture was quickly transferred to a 100℃ vacuum oven and dried for 24 hours. The dried product was then placed in an atmosphere-controlled furnace and sintered at 450℃ for 5 hours at a rate of 5℃ / min under argon atmosphere. After cooling, the mixture was crushed and sieved to obtain a ternary material matrix with the chemical formula: Li 1.02 Ni 0.93 Co 0.06 Mn 0.01 W 0.002 Cr 0.002 O2.

[0145] The ternary material matrix and the raw materials for the oxide coating layer were mixed at a mass ratio of 100:4. The raw materials for the oxide coating layer included LaAlO3, BaZrO3, and TiO2, with the molar ratio of La, Al, Ba, Ti, and Zr being 1:1:1:1:1.5, respectively. The mixture was then placed in an atmosphere-controlled furnace and heated to 550℃ at a rate of 2℃ / min under air atmosphere, holding for 10 hours to form an oxide coating layer on the ternary material matrix. The chemical formula of the oxide coating layer is LaAlO3. 0.33 Al 0.33 Ba 0.33 Ti 0.33 Zr 0.5 O3 is cooled and then crushed and sieved to obtain ternary cathode active material.

[0146] Example 2 This application provides a method for preparing a ternary cathode active material, which differs from Example 1 only in that: 1 mol of nickel-cobalt-manganese precursor (nickel-cobalt-manganese hydroxide Ni) is used. 0.95 Co 0.03 Mn 0.02 (OH)2), 1.04 mol LiOH·H2O, 0.002 mol Nb2O5, and 0.0005 mol Cr2O3 were mixed evenly to obtain a mixture; the raw materials for the oxide coating layer included LaAlO3, BaTiO3, and CeO2, and the molar ratio of La, Al, Ba, Ti, and Ce was 1:1:1:1:1.5.

[0147] Example 3 This application provides a method for preparing a ternary cathode active material, which differs from Example 1 only in that: 1 mol of nickel-cobalt-manganese precursor (nickel-cobalt-manganese hydroxide Ni) is used. 0.93 Co 0.06 Mn 0.01 (OH)2), 1.04 mol LiOH·H2O, 0.002 mol Nb2O5, and 0.001 mol MoO3 were mixed evenly to obtain a mixture; the raw materials for the oxide coating layer included LaNiO3, SrTiO3, and BaO, and the molar ratio of La, Ni, Sr, Ti, and Ba was 1:1:1:1:1.2.

[0148] Example 4 This application provides a method for preparing a ternary cathode active material, which differs from Example 1 only in that: 1 mol of nickel-cobalt-manganese precursor (nickel-cobalt-manganese hydroxide Ni) is used. 0.93 Co 0.06 Mn 0.01 (OH)2), 1.04 mol LiOH·H2O, 0.002 mol TeO2, and 0.002 mol MoO3 were mixed evenly to obtain a mixture; the raw materials for the oxide coating layer included MgAl2O4, SrTiO3, and CoO, and the molar ratio of Mg, Al, Sr, Ti, and Co was 0.5:1:1:1:1.

[0149] Example 5 This application provides a method for preparing a ternary cathode active material, which differs from Example 1 only in that: 1 mol of nickel-cobalt-manganese precursor (nickel-cobalt-manganese hydroxide Ni) is used. 0.93 Co 0.06 Mn 0.01 (OH)2), 1.04 mol LiOH·H2O, 0.002 mol TeO2, and 0.001 mol Sb2O5 were mixed evenly to obtain a mixture; the raw materials for the oxide coating layer included MgCr2O4, SrZrO3, and CeO2, and the molar ratio of Mg, Cr, Sr, Zr, and Ce was 1:2:1.33:1.33:2.

[0150] Example 6 This application provides a method for preparing a ternary cathode active material, which differs from Example 1 only in that: 1 mol of nickel-cobalt-manganese precursor (nickel-cobalt-manganese hydroxide Ni) is used. 0.93 Co 0.06 Mn 0.01(OH)2), 1.04 mol LiOH·H2O, 0.003 mol ZrO2, and 0.001 mol Sb2O5 were mixed evenly to obtain a mixture; the raw materials for the oxide coating layer included LaNiO3, SrZrO3, and CoO, and the molar ratio of La, Ni, Sr, Zr, and Co was 1:1:1:1:1.2.

[0151] Example 7 This application provides a method for preparing a ternary cathode active material, which differs from Example 1 only in that: 1 mol of nickel-cobalt-manganese precursor (nickel-cobalt-manganese hydroxide Ni) is used. 0.93 Co 0.06 Mn 0.01 (OH)2), 1.04 mol LiOH·H2O, 0.003 mol ZrO2, and 0.002 mol WO3 were mixed evenly to obtain a mixture; the raw materials for the oxide coating layer included SrTiO3, BaO, MgO, and CeO2, and the molar ratio of Sr, Ti, Ba, Mg, and Ce was 1.1:1.1:1:1:1.1.

[0152] Example 8 This application provides a method for preparing a ternary cathode active material, which differs from Example 1 only in that: 1 mol of nickel-cobalt-manganese precursor (nickel-cobalt-manganese hydroxide Ni) is used. 0.93 Co 0.06 Mn 0.01 (OH)2), 1.04 mol LiOH·H2O, and 0.0015 mol Nb2O5 were mixed evenly to obtain a mixture; the raw materials for the oxide coating layer included Al2O3, MgCr2O4, MgTiO3, and ZrO2, and the molar ratio of Al, Mg, Cr, Ti, and Zr was 2:1.75:1.5:1:1.5.

[0153] Example 9 This application provides a method for preparing a ternary cathode active material, which differs from Example 1 only in that: 1 mol of nickel-cobalt-manganese precursor (nickel-cobalt-manganese hydroxide Ni) is used. 0.93 Co 0.06 Mn 0.01 (OH)2), 1.04 mol LiOH·H2O and 0.003 mol WO3 were mixed evenly to obtain a mixture; and the mixture was heated to 500℃ at 2℃ / min and held for 10h in an air atmosphere to form an oxide coating layer on the ternary material matrix.

[0154] Example 10 This application provides a method for preparing a ternary cathode active material, which differs from Example 1 only in that: 1 mol of nickel-cobalt-manganese precursor (nickel-cobalt-manganese hydroxide Ni) is used. 0.93 Co 0.06 Mn 0.01 (OH)2), 1.04 mol LiOH·H2O and 0.002 mol TeO2 were mixed evenly to obtain a mixture; and the mixture was heated to 480℃ at 2℃ / min and held for 10h in an air atmosphere to form an oxide coating layer on the ternary material matrix.

[0155] Example 11 This application provides a method for preparing a ternary cathode active material, which differs from Example 1 only in that: 1 mol of nickel-cobalt-manganese precursor (nickel-cobalt-manganese hydroxide Ni) 0.93 Co 0.06 Mn 0.01 (OH)2), 1.04 mol LiOH·H2O, and 0.001 mol Sb2O5 were mixed evenly to obtain a mixture; and the mixture was heated to 580℃ at 2℃ / min and held for 10h in an air atmosphere to form an oxide coating layer on the ternary material matrix.

[0156] Example 12 This application provides a method for preparing a ternary cathode active material, which differs from Example 1 only in that the temperature is increased to 300°C at 2°C / min and held for 15 hours in an air atmosphere to form an oxide coating layer on the ternary material matrix.

[0157] Example 13 This application provides a method for preparing a ternary cathode active material, which differs from Example 1 only in that the temperature is increased to 700°C at 2°C / min and held for 5 hours in an air atmosphere to form an oxide coating layer on the ternary material matrix.

[0158] Example 14 This application provides a method for preparing a ternary cathode active material, which differs from Example 1 only in that the ternary material matrix and the raw materials of the oxide coating layer are mixed at a mass ratio of 100:3.

[0159] Example 15 This application provides a method for preparing a ternary cathode active material, which differs from Example 1 only in that the ternary material matrix and the raw materials of the oxide coating layer are mixed at a mass ratio of 100:2.5.

[0160] Example 16 This application provides a method for preparing a ternary cathode active material, which differs from Example 1 only in that the ternary material matrix and the raw materials for the oxide coating layer are mixed at a mass ratio of 100:4.5.

[0161] Example 17 This application provides a method for preparing a ternary cathode active material, which differs from Example 1 only in that the ternary material matrix and the raw materials of the oxide coating layer are mixed at a mass ratio of 100:2.

[0162] Example 18 This application provides a method for preparing a ternary cathode active material, which differs from Example 1 only in that the ternary material matrix and the raw materials of the oxide coating layer are mixed at a mass ratio of 100:6.

[0163] Example 19 This application provides a method for preparing a ternary cathode active material, which differs from Example 1 only in that: 1 mol of nickel-cobalt-manganese precursor (nickel-cobalt-manganese hydroxide Ni) is used. 0.93 Co 0.06 Mn 0.01 (OH)2), 1.04 mol LiOH·H2O, and 0.05 mol MoO3 were mixed evenly to obtain a mixture.

[0164] Comparative Example 1 This application provides a comparative example of a method for preparing a ternary cathode active material, which differs from Example 1 only in that no oxide coating layer is formed on the surface of the ternary material substrate.

[0165] Comparative Example 2 This application provides a comparative example of a method for preparing a ternary cathode active material, which differs from Example 1 only in that the ternary material matrix and the raw materials for the oxide coating layer are mixed at a mass ratio of 100:8.

[0166] Comparative Example 3 This application provides a comparative example of a method for preparing a ternary cathode active material, which differs from Example 1 only in that the ternary material matrix and the raw materials of the oxide coating layer are mixed at a mass ratio of 100:1.

[0167] Comparative Example 4 This application provides a comparative example of a method for preparing a ternary cathode active material, which differs from Example 1 only in that: 1 mol of a nickel-cobalt-manganese precursor (nickel-cobalt-manganese hydroxide Ni) is used. 0.83 Co 0.12 Mn 0.05 OH)2) and 1.04 mol LiOH·H2O were mixed evenly to obtain a mixture.

[0168] Comparative Example 5 This application provides a comparative example of a method for preparing a ternary cathode active material, which differs from Example 1 only in that: 1 mol of a nickel-cobalt-manganese precursor (nickel-cobalt-manganese hydroxide Ni) is used. 0.93 Co 0.06 Mn 0.01 (OH)2), 1.04 mol LiOH·H2O, and 0.06 mol MoO3 were mixed evenly to obtain a mixture.

[0169] Comparative Example 6 This application provides a comparative example of a method for preparing a ternary cathode active material, which differs from Example 1 only in that the temperature is increased to 850°C at 2°C / min and held for 5 hours in an air atmosphere to form an oxide coating layer on the ternary material matrix.

[0170] Comparative Example 7 This application provides a comparative example of a method for preparing a ternary cathode active material, which differs from Example 1 only in that the raw materials for the oxide coating layer include MgTiO3 and AlPO4, and the molar ratio of Mg, Ti, and Al is 1:1:1.

[0171] Comparative Example 8 This application provides a comparative example of a method for preparing a ternary cathode active material, which differs from Example 1 only in that the ternary material matrix precursor is not subjected to rapid water washing, drying, and reverse burning treatment.

[0172] To better understand the differences between the various embodiments and comparative examples, the material composition and process differences of the various embodiments and comparative examples are summarized and explained in the following table form, as shown in Table 1 and Table 2.

[0173] Table 1

[0174] Table 2

[0175] Test case Physicochemical performance testing of ternary cathode active materials Test method: (1) Morphological test Test method: The ternary positive electrode active materials prepared in Example 1, Comparative Example 2 and Comparative Example 3 were used as samples, and images of each sample were acquired using a Hitachi SU 8010 scanning electron microscope (SEM).

[0176] See Figure 2 , Figure 3 and Figure 4The ternary cathode active material prepared in Example 1 has a continuous thin film coating layer on its surface, while the coating layer in Comparative Example 2 is too thick, and only dot-like coating is achieved in Comparative Example 3.

[0177] (2) Component testing of ternary cathode active materials Test Method: The ternary cathode active material prepared in Example 1 was used as the sample. A cross-section was obtained by focused ion beam cutting, with the temperature controlled ≤50℃ during the cutting process to avoid material oxidation or element migration. The cross-section was then subjected to gradient grinding at 800 mesh, 1500 mesh, and 3000 mesh, followed by polishing with 0.5μm diamond polishing slurry until no obvious scratches were visible and the internal microstructure was clearly exposed. After polishing, the sample was ultrasonically cleaned three times with anhydrous ethanol for 5 minutes each time to remove residual abrasive material and dried with nitrogen to prevent the introduction of impurities such as Na and K. The processed sample was fixed on a conductive sample stage, and the secondary spherical cross-section was observed using scanning electron microscopy (SEM) in secondary electron imaging mode (SEI) at an accelerating voltage of 10-15kV and a magnification of 5000-20000x. Individual complete spherical or polygonal primary particles were identified, and the shell and substrate were located based on morphological differences. Subsequently, an energy-dispersive X-ray spectrometer (EDS) coupled with SEM was used. Under test conditions of 15 kV accelerating voltage, 8-10 mm working distance, 30-60 s scan time, and 5-10 nm spot diameter, elemental scans were performed on the matrix region at the center of the primary particle and the uniform outer shell region. The elemental types and characteristic X-ray intensities were recorded. Using EDS software (Oxford INCA) with ZAF correction, the characteristic X-ray intensities were converted into elemental molar percentages. Combined with elemental analysis, the core-shell structure was verified. Specifically, the matrix region showed the presence of Ni, Co, and Mn as the main elements, accompanied by a small amount of dopant elements. The outer shell region showed the presence of various high-entropy oxide elements and was essentially devoid of Ni, Co, and Mn, showing a significant difference in elemental composition from the matrix region. This indicates that it is a high-entropy oxide coating layer. The regionalization of elemental composition in both regions confirms that the primary particle has a core-shell structure.

[0178] See Figure 5 and Figure 6 (in, Figure 5 This is a cross-sectional view of the ternary cathode active material prepared in Example 1. Figure 6 The image shows the EDS diagram of the ternary cathode active material prepared in Example 1. The cross-section of the secondary spheres of the ternary cathode active material prepared in Example 1 shows complete primary particles. At the same time, the elemental scan of the complete primary particles reveals that the main elements Ni, Co, and Mn are distributed in the matrix region, while the high-entropy dopants La, Al, Ba, Ti, and Zr are only distributed in the shell region. This indicates that the primary particles have a core-shell structure, and the matrix material is a ternary material and the shell material is a high-entropy oxide coating layer.

[0179] In addition, the XRD test was performed on the ternary positive electrode active materials prepared in Examples 1-2 and Comparative Example 1.

[0180] See Figure 7 In Examples 1 and 2, there are (110) crystal plane diffraction peaks belonging to the perovskite phase at diffraction angles of 15° to 18°. In addition, combined with the above EDS results, it can be seen that the oxide coating is a perovskite-type high-entropy oxide coating.

[0181] (3) Thickness test of the coating layer Test method: Under 25℃ conditions, the positive electrode active material of Example 1 was uniformly dispersed in the central area of ​​a copper mesh with conductive adhesive (specifically: the positive electrode powder was first uniformly dispersed in the solution using ultrasonic vibration, and the ultrasonic vibration process broke the secondary spheres and dispersed them into primary particles, and then the solution containing the primary particles was coated on the copper mesh to obtain the primary particles of the positive electrode active material). Then, the copper mesh loaded with primary particles was fixed on a focused ion beam (FIB) sample stage, and the FIB system was used for profile preparation. The ion beam acceleration voltage was set to 30kV. First, a large beam current of 100pA was used to perform preliminary etching on the target primary particles to remove the surface oxide layer and adsorbed contaminants. Then, the beam current was switched to 30pA for fine cutting to form an ultrathin profile with a thickness of 50-100nm. During the cutting process, the profile morphology was monitored by real-time scanning imaging mode to avoid excessive etching that would cause particle breakage. At the same time, a 5-10nm thick Pt protective layer was deposited on the profile surface to prevent the profile from being damaged by the ion beam during subsequent transfer and testing. The prepared cross-sectional copper mesh sample was carefully transferred to the transmission electron microscope (TEM) sample chamber, ensuring a vacuum level ≥1×10⁻⁶ in the sample chamber. -5 Pa was used in high-resolution transmission electron microscopy (HRTEM) mode with an accelerating voltage of 200 kV. A cross-sectional area of ​​a single, complete primary particle was selected, and the electron beam focusing precision was adjusted to ensure a clear diffraction pattern. The diffraction pattern was then captured using selected area electron diffraction (SAED) mode. The diffraction pattern was analyzed using the accompanying TEM analysis software (Gatan Digital Micrograph). By comparing with the JCPDS standard PDF card, the interplanar spacing corresponding to diffraction rings or spots was identified, thus clarifying the crystal lattice structure of the cathode material matrix and coating layer. Simultaneously, areas with uniform coating layer thickness were selected from the high-resolution TEM images. For details, please refer to [reference needed]. Figure 8 It can be seen that the material surface has a relatively uniform high-entropy oxide protective layer. Using the high-precision length measurement tool built into the software, the thickness values ​​at least 5 different locations are measured along the direction perpendicular to the interface between the coating layer and the substrate, and the arithmetic mean is taken as the final thickness of the coating layer.

[0182] (4) L / H*S 0.5 test L / H Test: Step 1: Identification and labeling of primary particles (single and / or single-particle-like particles). Images of the corresponding secondary spheres are acquired using a field emission scanning electron microscope (SEM) at 3000x magnification. The images are then analyzed using ImageJ software (1.46r, Win64 version). Primary particles not labeled by the software, not fully labeled, or labeled with errors are manually labeled to complete the identification and labeling of primary particles (single and / or single-particle-like particles) in the image. Step 2: The images after primary particle identification and labeling are imported into ImageJ software for analysis. Scale settings are completed based on the SEM images. The particle size of the primary particles in the images is analyzed using the "major axis," "minor axis," "Area," "Round," and "Solidity" analysis functions. According to the software manual (ImageJ User Guide IJ 1.46r), the major and minor axes of the primary particles on their two-dimensional projection are obtained. Select five image regions according to steps 1-2 above, count the major and minor axes of all primary particles in the cross section, calculate their average values, and finally calculate L / H.

[0183] Specific surface area S test: Test method: Weigh the total weight of the empty small test tube and stopper. Immerse the positive electrode active material powder sample in anhydrous ethanol for 4 hours. Then, remove the powder sample and dry it in an oven at 105℃ for half an hour. Next, place the powder sample into a sample tube and weigh the total weight of the powder sample, small test tube, and stopper to calculate the sample mass. Turn on the degassing station and place the small test tube containing the powder sample into the degassing station at 105℃. Purge with nitrogen (pure nitrogen) for 30 minutes, cool for 15 minutes, and test on the instrument at 25℃ and 60% humidity. Use P / P0 in the range of 0.05~0.25 as the x-axis, and P / V(P0) = P / P0 ... P) is the Y-axis. By plotting the BET equation and performing linear fitting, the slope and intercept of the straight line are obtained, and the BET specific surface area S of the powder sample can be calculated.

[0184] L / H and S can be obtained from the test, and then L / H*S can be calculated. 0.5 The test results are then compiled in Table 3.

[0185] (5) Test of lithium content on material surface The method is as follows: The potentiometric titration method for alkali content testing is adopted, specifically including: weighing 1 g of sample and dissolving it in 100 mL of ultrapure water, stirring in a closed container for 30 min, and immediately filtering to obtain filtrate. 5 mL of each sample filtrate is transferred and titrated with 0.05 mol / L standard hydrochloric acid solution on a potentiometric titrator to test the residual alkali content on the sample surface. The results are then statistically summarized in Table 3.

[0186] Table 3

[0187] (6) Electrical performance testing of ternary cathode active materials The test method involved assembling the ternary cathode active materials prepared in Examples 1-19 and Comparative Examples 1-8 into 2032 coin cells. The 0.2C discharge specific capacity, 1C / 0.2C rate capability, and capacity retention rate after 100 cycles at 1C were then tested for each sample. The test results are summarized in Table 4.

[0188] The assembly steps for the 2032 button cell are as follows: Preparation of the positive electrode sheet: Using the provided ternary positive electrode active material as the positive electrode material, it is uniformly dispersed with binder PVDF and carbon black conductive agent Super-P in an appropriate amount of N-methylpyrrolidone at a mass ratio of 90:5:5 to obtain a positive electrode slurry; the positive electrode slurry is coated onto aluminum foil, dried at 120℃, rolled, and punched to form a positive electrode sheet with a diameter of 13mm. The loading of the positive electrode active material in the positive electrode sheet is approximately 12 mg / cm³. 2 .

[0189] Battery assembly: In an argon-filled glove box, a 2032 coin cell is assembled using a lithium sheet as the negative electrode, a polypropylene microporous membrane (Celgard2400) as the separator, and 1M LiPF6 / ethylene carbonate (EC) + dimethyl carbonate (DMC) as the electrolyte.

[0190] The testing steps for electrical performance are as follows: Electrochemical performance test: At 25℃, the following electrochemical performance tests were conducted on the 2032 coin cell using the Xinwei Battery Test System: (1) Charge and discharge test was conducted at 0.2C to evaluate the first charge and discharge specific capacity of the cathode material; (2) Charge and discharge test was conducted at 0.2C and 1C respectively to evaluate the rate performance of the material; (3) Cycled 100 times (100T) at 1C to evaluate the cycle performance of the material; The charge and discharge voltage window of the battery is 2.5V~4.52V, and the charge and discharge current density at 1C (1 times the rated capacity) is 230 mA / g.

[0191] Table 4

[0192] See Table 4 and Figure 9 As can be seen from the test results of Examples 1-19 and Comparative Examples 1-8, using the ternary positive electrode active material provided in the embodiments of this application as raw material, since it has a core-shell structure and simultaneously satisfies 3≤L / H*S 0.5 ≤5, so that the corresponding battery has better capacity, rate performance and cycle performance.

[0193] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. A ternary cathode active material, characterized in that, The ternary cathode active material comprises a ternary material matrix and an oxide coating layer on the surface of the ternary material matrix. The primary particles of the ternary cathode active material have an average major diameter of L μm and an average minor diameter of H μm. The specific surface area of ​​the ternary cathode active material is S m². 2 / g, and the values ​​of L, H, and S satisfy: 3≤L / H*S 0.5 ≤5.

2. The ternary cathode active material according to claim 1, characterized in that, 1.9 ≤ L / H ≤ 2.3, or / and, 3.5m 2 / g≤S≤4.15 m 2 / g.

3. The ternary cathode active material according to claim 2, characterized in that, 0.39 μm≤L≤0.97 μm, 0.15 μm≤H≤0.46 μm.

4. The ternary cathode active material according to any one of claims 1 to 3, characterized in that, The surface lithium content of the ternary cathode active material is ≤3000 ppm.

5. The ternary cathode active material according to any one of claims 1 to 3, characterized in that, The ternary material matrix includes a ternary nickel-cobalt-manganese active material, and / or the oxide coating layer is made of a high-entropy oxide. Optionally, the thickness of the oxide coating layer is 2.5~8.5 nm.

6. The ternary cathode active material according to claim 5, characterized in that, The high-entropy oxide is a perovskite-type high-entropy oxide; Optionally, the metal element in the high-entropy oxide is selected from at least five of the following: La, Al, Ni, Ca, Sr, Ti, Ba, Zr, Co, Mg, Ce, and Cr.

7. The ternary cathode active material according to claim 5, characterized in that, In the ternary nickel-cobalt-manganese active material, the average valence state of the metal elements other than lithium is E1, and the average valence state of all metal elements in the high-entropy oxide is E2. The absolute value of the difference between E1 and E2 is no greater than 0.

46. Alternatively, 2.84 ≤ E1 ≤ 2.98, or / and 2.67 ≤ E2 ≤ 3.

43.

8. The ternary cathode active material according to claim 6 or 7, characterized in that, In the ternary nickel-cobalt-manganese active material, the ratio of the total molar amount of nickel, cobalt, and manganese to the molar amount of lithium is 1:(0.95~1.05). Optionally, the molar ratio of nickel to the total molar ratio of nickel, cobalt, and manganese is (0.8~0.98):1, and the molar ratio of cobalt to the total molar ratio of nickel, cobalt, and manganese is (0.02~0.2):

1. Optionally, the ternary nickel-cobalt-manganese active material further includes a doping element M, wherein the doping element M is selected from at least one of W, Cr, Nb, Mo, Te, Sb and Zr; Optionally, the molar ratio of the dopant element M to the total molar ratio of nickel, cobalt, and manganese is (0.002~0.05):

1.

9. A method for preparing a ternary cathode active material, characterized in that, Includes the following steps: After mixing the raw materials of the ternary material matrix and the oxide coating layer, a first sintering treatment is performed to form an oxide coating layer on the surface of the ternary material matrix, thereby obtaining the ternary positive electrode active material. Furthermore, the average major diameter of the primary particles of the ternary cathode active material is L μm, the average minor diameter is H μm, and the specific surface area of ​​the ternary cathode active material is S m². 2 / g, and the values ​​of L, H, and S satisfy: 3≤L / H*S 0.5 ≤5.

10. The method for preparing the ternary cathode active material according to claim 9, characterized in that, The method for preparing the ternary material matrix includes the following steps: A second sintering process is performed after mixing lithium source, nickel source, cobalt source, manganese source and dopant element M source, wherein the molar ratio of the dopant element M to the total molar ratio of nickel, cobalt and manganese is (0.002~0.05):1, to obtain a ternary material matrix precursor; The ternary material matrix precursor was sequentially subjected to water washing, drying and calcination to obtain the ternary material matrix. Optionally, in the sintering treatment step, the treatment temperature is 700~1100℃ and the treatment time is 10~24 h; or / and in the water washing treatment step, the treatment temperature is 70~100℃, the solid-liquid ratio is 1 g:(1~3) mL, and the water washing time is 30~60s; or / and in the reverse sintering treatment step, the treatment temperature is 400~600℃ and the treatment time is 3~10 h.

11. The method for preparing the ternary positive electrode active material according to claim 9 or 10, characterized in that, The step of mixing the raw materials of the ternary material matrix and the oxide coating layer and then performing a first sintering treatment includes: The raw materials of the ternary material matrix and the oxide coating layer are mixed, wherein the mass ratio of the ternary material matrix to the raw materials is 100:(2~6), to obtain a mixture; The mixture is sintered at 300~700℃ to obtain the ternary positive electrode active material; Optionally, the heat preservation sintering step takes 5 to 15 hours.

12. A battery cell, characterized in that, The battery cell comprises a ternary cathode active material as described in any one of claims 1 to 8 or a ternary cathode active material prepared by any one of claims 9 to 11.

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