Modified high-nickel ternary positive electrode material, preparation method and application thereof

Abstract

This application relates to a modified high-nickel ternary cathode material, its preparation method, and its applications. The modified high-nickel ternary cathode material includes a substrate and first, second, and third coating layers sequentially coated on the substrate; the substrate includes Li. 1.1‑a M a (Ni b Co c Mn d ) 1‑ e A e O2E f 0.01≤a≤0.2, 0.8≤b≤1, 0.01≤c≤0.2, 0.01≤d≤0.2, 0<e≤0.05, 0≤f≤0.1; M is selected from Na, K, Rb, Cs; A is selected from Al, Mg, Zr, Ti, W, Y, B, Co, Nb, Mo, Sb, Sr; E is selected from F, Cl, Br, and I; the first, second, and third coating layers respectively include Li2SO4, a cobalt-containing compound, and a compound containing M1. This invention can simultaneously improve the battery's capacity, cycle performance, structural stability, and safety, without introducing toxic or harmful products.

Description

Technical Field

[0001] This application relates to the field of battery materials, specifically to a modified high-nickel ternary cathode material and its preparation method, as well as secondary batteries, battery modules, battery packs and electrical devices formed from the material. Background Technology

[0002] In the ternary cathode material product structure, considering the need to reduce costs and improve range for electric vehicles, high-nickel ternary cathode materials have become an industry trend with continuously increasing demand, representing a new growth driver for the nickel industry chain. For high-nickel ternary cathode materials, battery capacity, cycle performance, safety performance, and structural stability are all crucial performance characteristics, but existing technologies typically cannot simultaneously achieve all of these. For example, patent application CN113241433A discloses a dual-doped coated composite modified ternary cathode material and its preparation method. A ternary precursor is synthesized via co-precipitation, and an alkali metal sulfide is added and dry-mixed with the ternary precursor for sintering to obtain an alkali metal-doped ternary material. Then, a transition metal salt, sodium sulfide, and the ternary material are added to an organic solvent, and a layer of transition metal sulfide is co-precipitated and coated onto the surface of the ternary material to obtain the finished product. The transition metals include one or more of Sb, Bi, and Sn. Although the above techniques can improve the structure and interface stability of ternary materials by alkali metal doping and transition metal sulfide coating, the addition of alkali metal sulfides during alkali metal doping can produce toxic gases such as SO2 when the compound is sintered at high temperature in an oxygen atmosphere, which can harm the environment and human health. Furthermore, the subsequent transition metal sulfide coating introduces sodium salts that participate in the reaction, which reduces the material's capacity.

[0003] Therefore, this invention is proposed. Summary of the Invention

[0004] The main objective of this invention is to provide a modified high-nickel ternary cathode material and its preparation method. This material can simultaneously improve the battery's capacity, cycle performance, structural stability, and safety through substrate doping and three-layer coating, while also avoiding the introduction of toxic or harmful products during the preparation process. Therefore, this material has significant advantages when applied to secondary batteries, battery modules, battery packs, and electrical devices.

[0005] To achieve the above objectives, the present invention provides the following technical solutions.

[0006] A first aspect of the present invention provides a modified high-nickel ternary cathode material, comprising a substrate and a first coating layer, a second coating layer and a third coating layer sequentially coated on the substrate;

[0007] The substrate includes Li 1.1-a M a (Nib Co c Mn d ) 1-e A e O2E f And 0.01≤a≤0.2, 0.8≤b≤1, 0.01≤c≤0.2, 0.01≤d≤0.2, 0<e≤0.05, 0≤f≤0.1; wherein M is selected from one or more of the alkali metal elements Na, K, Rb, and Cs, A is selected from one or more of Al, Mg, Zr, Ti, W, Y, B, Co, Nb, Mo, Sb, and Sr, and E is selected from one or more of F, Cl, Br, and I; the first coating layer includes Li2SO4, the second coating layer includes a cobalt-containing compound, and the third coating layer includes a compound containing M1; wherein M1 includes one or more of Al, Ti, B, W, Nb, and Sb.

[0008] The modified high-nickel ternary cathode materials described above can improve various properties such as capacity, cycle performance, structural stability, and safety by doping the substrate with a specific proportion of alkali metals, transition metals, halogens, etc., and coating it with three layers of materials (lithium sulfate, cobalt-containing compounds, and Al, Ti, and B-containing compounds) in a specific order. In other words, they take into account many key performance aspects of ternary cathode materials in application, thus providing significant advantages for their application in secondary batteries, battery modules, battery packs, and electrical devices.

[0009] Specifically, in terms of material composition, although the aforementioned elemental doping and the three coating layers each have their own main roles, ultimately it is the complementary synergistic effect of all components that improves the material properties.

[0010] For example, regarding the substrate, on the one hand, doping with alkali metal M elements to replace lithium sites can increase the lithium-ion transport channels, effectively improving the material's initial efficiency and capacity, and further enhancing the structural stability of the material during lithium-ion insertion / extraction, thus improving the material's cycle performance. On the other hand, doping with A elements in the substrate allows for doping into the NCM transition metal element positions of the ternary material, further improving the material's structural stability and long-term performance. Furthermore, doping with halogens in the substrate can achieve oxygen site doping, improving the material's safety performance.

[0011] Regarding the coating layer, on the one hand, uniformly coating the surface or grain boundaries of the cathode material particles with Li₂SO₄ can effectively inhibit side reactions at the interface between the cathode material, especially high-nickel cathode materials, and the electrolyte, as Li₂SO₄ is not easily soluble in the electrolyte at high temperatures or during long-term cycling. This improves the long-term performance, such as cycle performance and storage performance, as well as safety performance. On the other hand, coating the particle surface with Co compounds can reduce surface lithium impurities and further block side reactions between high-valence Ni ions on the surface and the electrolyte, while improving the rate performance and cycle performance of the material. Furthermore, coating the outer layer with Al, B, or Ti compounds can further significantly improve interfacial side reactions between the material and the electrolyte, improving the material's storage and cycle performance.

[0012] The substrate and each coating layer work together to improve the overall performance of the material based on the above main functions.

[0013] For the aforementioned cathode material, the content of each element has a significant impact on product performance, and can be any value within the range specified above. For example, a can be 0.01, 0.03, 0.05, 0.07, 0.09, 0.1, 0.13, 0.15, 0.17, 0.19, 0.2, etc., with preferred ranges including 0.01–0.05, 0.09–0.15, or 0.15–0.2, etc. b can be 0.8, 0.83, 0.85, 0.87, 0.89, 0.9, 0.93, 0.95, 0.97, 0.99, 1, etc. c can be selected from 0.01, 0.03, 0.05, 0.07, 0.09, 0.1, 0.13, 0.15, 0.17, 0.19, 0.2, etc., with preferred ranges including 0.01~0.05, 0.09~0.15, or 0.15~0.2, etc. d can be selected from 0.01, 0.03, 0.05, 0.07, 0.09, 0.1, 0.13, 0.15, 0.17, 0.19, 0.2, etc., with preferred ranges including 0.01~0.05, 0.09~0.15, or 0.15~0.2, etc. e can be 0.001, 0.005, 0.01, 0.03, 0.05, etc., with preferred ranges including 0.001 to 0.01, or 0.01 to 0.03, 0.01 to 0.05, etc.

[0014] In some embodiments, the molar ratio of alkali metal M atoms to S atoms is (0.2–4.2):1 to further improve cycle performance. Optional ratios include 0.2:1, 0.5:1, 0.7:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, and 4.2:1. Preferred ranges include (1–3):1, (0.6–2.8):1, (1.5–2.5):1, and (0.36–1.39):1.

[0015] In some embodiments, it is necessary to control the ratio of lithium doping to the total amount of nickel, cobalt and manganese in the substrate, and control (1.1-a):(b+c+d) within the range of 0.9 to 1.1, so as to improve long-term performance such as cycle performance and storage performance, as well as safety performance.

[0016] In some embodiments, based on the modified high-nickel ternary cathode material, the content of alkali metal M atoms is 100–5000 ppm, optionally 500–2000 ppm. The above scheme controls the alkali metal doping amount within a reasonable range to more fully improve the overall performance, including cycle performance, storage performance, and capacity. Excessive doping causes too many lithium sites to be replaced by alkali metal ions, which can actually reduce the active lithium ion concentration and thus decrease the capacity.

[0017] In some embodiments, based on the modified high-nickel ternary cathode material, the S atom content is 200–5000 ppm, optionally 1000–3000 ppm. Although coating with a first layer of Li₂SO₄ can effectively improve the side reactions between the material and the electrolyte, the coating amount needs to be controlled within a reasonable range to provide good protection without affecting the material's capacity.

[0018] In some embodiments, based on the modified high-nickel ternary cathode material, the cobalt atom content in the second coating layer is 1000–20000 ppm, optionally 5000–15000 ppm. In this invention, a Co coating compound is used to uniformly and effectively coat the cathode material substrate surface, further improving the interfacial side reactions between the material and the electrolyte. Simultaneously, using the aforementioned optional coating amount effectively reacts with residual lithium on the surface to generate Li2CoO3 active material without producing excessive residual inactive Co-containing compounds, thus improving the material's capacity, rate performance, and cycle performance.

[0019] In some embodiments, based on the modified high-nickel ternary cathode material, the content of M1 atoms is 100–5000 ppm, optionally 500–2000 ppm. Coating with compounds containing M1 can further significantly improve interfacial side reactions of the material, enhance the material's cycle life, storage performance, and safety. By controlling its content within the aforementioned reasonable range, the modification effect can be maximized.

[0020] In some embodiments, the volumetric particle size distribution (Dv50) of the modified high-nickel ternary cathode material is 3–20 μm, optionally 3–15 μm. By controlling the particle size distribution of the material, it can be made to have a suitable particle size, thereby increasing the specific surface area, which is beneficial for full reaction and maintaining good structural stability.

[0021] In some embodiments, the particle size distribution of the modified high-nickel ternary cathode material has a particle size distribution radius (Dv90-Dv10) / Dv50 ≥ 1.0 to significantly improve the volumetric energy density of the material. Optionally, (Dv90-Dv10) / Dv50 ≥ 1.2.

[0022] In some embodiments, the compaction density of the powdered modified high-nickel ternary cathode material under a pressure of 5 tons is ≥3.45 g / cc. Compaction density is closely related to the electrode's specific capacity, efficiency, internal resistance, and battery cycle performance. The ternary material provided by this invention has a suitable compaction density, resulting in good overall performance in batteries.

[0023] A second aspect of the present invention provides a method for preparing a modified high-nickel ternary cathode material, comprising the following steps:

[0024] The sulfates of nickel, cobalt, and manganese are reacted with an alkaline solution in an alkaline environment to form a high-nickel ternary precursor slurry; the alkaline solution includes a hydroxide solution of an alkali metal M, wherein M includes one or more of Na, K, Rb, and Cs;

[0025] The high-nickel ternary precursor slurry is dried to obtain the precursor product;

[0026] The lithium salt, the precursor product, the compound containing element A, and the compound containing element E are mixed and sintered for the first time to obtain a high-nickel ternary cathode material matrix doped with alkali metal, element A, and element E and coated with a first coating layer.

[0027] Then, the high-nickel ternary cathode material matrix is ​​mixed with a cobalt-containing compound and sintered a second time, followed by a mixture with a M1-containing compound and sintered a third time to obtain a modified high-nickel ternary cathode material.

[0028] The modified high-nickel ternary cathode material includes a substrate and a first coating layer, a second coating layer, and a third coating layer sequentially coated on the substrate;

[0029] Wherein, the substrate is Li 1.1-a M a (Ni b Co c Mn d ) 1-e A e O2E fAnd 0.01≤a≤0.2, 0.8≤b≤1, 0.01≤c≤0.2, 0.01≤d≤0.2, 0<e≤0.05, 0≤f≤0.1; wherein M is selected from one or more of the alkali metal elements Na, K, Rb, and Cs, A is selected from one or more of Al, Mg, Zr, Ti, W, Y, B, Co, Nb, Mo, Sb, and Sr, and E is selected from one or more of F, Cl, Br, and I;

[0030] The first coating layer includes Li2SO4, the second coating layer includes a cobalt-containing compound, and the third coating layer includes a compound containing M1; wherein M1 includes one or more of Al, Ti, B, W, Nb, and Sb.

[0031] The above preparation method can achieve the following technical effects:

[0032] On the one hand, removing the washing process (usually alkaline washing) from the existing precursor synthesis process can significantly reduce the process cost and provide alkali metal ion sources and sulfate ion sources for subsequent cathode material sintering doping with alkali metal ions and coating Li2SO4.

[0033] On the other hand, due to the presence of Na on the precursor surface + and SO4 2- Uniform ion coating is beneficial for uniform doping of Na and uniform coating of Li2SO4 during the sintering of cathode materials, which further improves the performance of the materials.

[0034] On the other hand, by using this cathode material synthesis method, three layers of coating material can be uniformly coated on the surface of high-nickel cathode material. While maintaining high capacity, it can further improve the interfacial side reactions on the surface of high-nickel material and improve the long-term cycling and storage performance of the material.

[0035] In summary, this method has the advantages of low cost, improvement of multiple properties of materials, and high efficiency.

[0036] In some embodiments, the pH value of the alkaline solution environment is controlled by ammonia water, and the pH value is between 11 and 12, so as to stably synthesize a precursor product with radially distributed, continuous and stable wide distribution of precursor whiskers, preferably between 11.1 and 11.7.

[0037] In some embodiments, the ammonia concentration in the alkaline solution environment is 0.2 to 0.6 mol / L, which is also to ensure the stable synthesis of a precursor product with radially distributed, continuous, and stable broad distribution of precursor whiskers, preferably 0.3 to 0.5 mol / L.

[0038] In some embodiments, prior to the drying process, the high-nickel ternary precursor slurry is sequentially centrifuged and rinsed with water. Water rinsing removes excess reactants and allows for control of the doping amount and subsequent lithium sulfate coating by adjusting the rinsing intensity (e.g., water volume), achieving uniform doping of alkali metal ions and in-situ surface or grain boundary coating of lithium sulfate, thereby significantly improving the material's capacity.

[0039] Based on the above rinsing mechanism, in some embodiments, the weight of water used for rinsing is 0.5 to 5 times the weight of the high-nickel ternary precursor slurry, and can be selected as 1 to 3 times.

[0040] In some embodiments, the conditions for the first sintering are: a sintering temperature of 700–950°C, a sintering time of 10–20 h, and a sintering atmosphere of air or O2. Using this initial sintering process, high-nickel ternary cathode materials with excellent crystal structures can be sintered, and alkali metals, alumina (A) and eutectic (E) elements can be uniformly and effectively doped, and a first layer of Li2SO4 coating can be uniformly coated on the surface of the high-nickel ternary cathode material.

[0041] In some embodiments, the conditions for the second sintering are: a sintering temperature of 500–800°C, optionally 550–750°C; a sintering time of 5–15 h or 5–10 h; and a sintering atmosphere of air or O2. Using this sintering process, the Co-containing compound can effectively react with the lithium impurities on the surface of the cathode material matrix, and can also firmly coat the Co-containing compound onto the surface of the cathode material particles without penetrating into the inner layers of the particles, thus improving the lithium impurities and coating effect.

[0042] In some embodiments, the conditions for the third sintering are: a sintering temperature of 200–500°C, optionally 200–400°C; a sintering time of 5–15 h, optionally 5–10 h; and a sintering atmosphere of air or O2. Using this sintering process, compounds containing element M can be firmly coated onto the surface of the cathode material particles without penetrating into the inner layers of the particles, thus improving the coating effect.

[0043] In some embodiments, the lithium salt is one or a mixture of two of lithium carbonate and lithium hydroxide;

[0044] And / or,

[0045] The cobalt-containing compounds include one or more of the following: Co3O4, Co(OH)2, CoO, CoOOH, cobalt acetate, cobalt oxalate, and CoCO3.

[0046] And / or,

[0047] The compounds containing the element M1 include one or more of the following: oxides, hydroxides, and carbonates of M1.

[0048] And / or,

[0049] The compounds containing element A include one or more of oxides, hydroxides, and carbonates of A;

[0050] And / or,

[0051] The compounds containing element E include one or more of metallic compounds and non-metallic compounds containing element E, and the element E includes one of F, Cl, Br or I.

[0052] In some embodiments, water of 10-40% of the reactor volume is added as a base liquid before the reaction.

[0053] In this embodiment, selecting suitable lithium salts and compounds containing M1 elements can introduce lithium elements while avoiding the introduction of harmful impurities. Simultaneously, the appropriate selection of compounds containing cobalt, a, and e in the coating layer not only matches the sintering process of this invention, ensuring coating quality, but also avoids adverse effects on electrochemical reaction performance.

[0054] Meanwhile, choosing an appropriate amount of water as the base liquid can ensure the uniformity of doping and promote the rapid adsorption of salt, thereby improving the preparation efficiency.

[0055] A third aspect of the present invention provides a secondary battery comprising the modified high-nickel ternary cathode material described above, or comprising the modified high-nickel ternary cathode material obtained according to the preparation method described above.

[0056] A fourth aspect of the present invention provides a battery module including the secondary battery described above.

[0057] A fifth aspect of the present invention provides a battery pack including the battery module described above.

[0058] A sixth aspect of the present invention provides an electrical device comprising at least one of the secondary battery, the battery module, or the battery pack described above.

[0059] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0060] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0061] Figure 1 This is a SEM image of the high-nickel cathode material prepared in Example 1 of this invention;

[0062] Figure 2 The first charge-discharge curve of the high-nickel cathode material prepared in Example 1 of this invention was used to fabricate a coin cell.

[0063] Figure 3 Comparison curves of 25°C cycling of full cells made from the high-nickel cathode materials prepared in Comparative Example 1 and Example 1 of this invention;

[0064] Figure 4 Comparison curves of gas expansion during storage at 70°C for full cells made from the high-nickel cathode materials prepared in Comparative Example 1 and Example 1 of this invention;

[0065] Figure 5 This is a schematic diagram of a secondary battery according to one embodiment of this application;

[0066] Figure 6 yes Figure 5 An exploded view of a secondary battery according to an embodiment of this application is shown;

[0067] Figure 7 This is a schematic diagram of a battery module according to one embodiment of this application;

[0068] Figure 8 This is a schematic diagram of a battery pack according to one embodiment of this application;

[0069] Figure 9 yes Figure 8 An exploded view of a battery pack according to one embodiment of this application is shown;

[0070] Figure 10 This is a schematic diagram of an electrical device that uses a secondary battery as a power source according to one embodiment of this application.

[0071] Explanation of reference numerals in the attached figures:

[0072] 1 Battery pack; 2 Upper housing; 3 Lower housing; 4 Battery module; 5 Secondary battery; 51 Casing; 52 Electrode assembly; 53 Top cover assembly Detailed Implementation

[0073] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0074] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0075] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0076] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0077] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0078] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0079] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0080] As described in the background section, existing high-nickel ternary cathode materials cannot simultaneously achieve multiple performance aspects such as battery capacity, cycle performance, safety performance, and structural stability. Therefore, this invention provides a modified high-nickel ternary cathode material and its preparation method for use in products such as secondary batteries, battery modules, battery packs, and electrical devices.

[0081] The modified high-nickel ternary cathode material of this invention mainly involves doping a high-nickel ternary cathode material with multiple elements, followed by sequentially coating it with three different materials (a first coating layer, a second coating layer, and a third coating layer) from the inside out. These multifaceted modifications can simultaneously improve battery capacity, cycle performance, safety performance, and structural stability. The corresponding preparation method includes the following main steps: first, a precursor product is formed using nickel-cobalt-manganese sulfate and an alkaline solution; then, sintering is performed to sequentially complete the doping and formation of the first coating layer; subsequently, compounds containing cobalt and compounds containing M1 are introduced stepwise and sintered one by one, thereby stepwise completing the formation of the second and third coating layers.

[0082] The type of doping element, the type of coating material, the amount and / or ratio of each element, the type of reactants, the sintering conditions, and the pretreatment conditions all have a significant impact on the final performance of the product, and there is a synergistic effect between each doping element and each coating layer. The following describes the technical effects achieved by the present invention through some examples.

[0083] In addition, the following description, with appropriate reference to the accompanying drawings, will illustrate the secondary battery, battery module, battery pack, and power device made of the modified high-nickel ternary cathode material of this application.

[0084] Typically, a secondary battery consists of a positive electrode, a negative electrode, an electrolyte, and a separator. During charging and discharging, active ions move back and forth between the positive and negative electrodes, inserting and releasing. The electrolyte acts as a conductor between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, primarily prevents short circuits while allowing ions to pass through.

[0085] [Positive electrode plate]

[0086] The positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector, the positive electrode film layer including the modified high-nickel ternary positive electrode material of the first aspect of this application.

[0087] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0088] In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0089] The positive electrode active material uses the modified high-nickel ternary positive electrode material provided by this invention.

[0090] In some embodiments, the positive electrode film layer may optionally include a binder. As an example, the binder may include at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0091] In some embodiments, the positive electrode film may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0092] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0093] [Negative electrode plate]

[0094] The negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector, the negative electrode film layer including a negative electrode active material.

[0095] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0096] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0097] In some embodiments, the negative electrode active material may be a negative electrode active material known in the art for use in batteries. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0098] In some embodiments, the negative electrode film layer may optionally include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0099] In some embodiments, the negative electrode film may optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0100] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0101] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as the negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0102] [Electrolytes]

[0103] The electrolyte acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific restrictions on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte can be liquid, gel, or entirely solid.

[0104] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0105] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0106] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0107] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0108] [Isolation membrane]

[0109] In some embodiments, the secondary battery also includes a separator. This application does not impose any particular limitation on the type of separator; any known porous separator with good chemical and mechanical stability can be selected.

[0110] In some embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0111] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

[0112] In some embodiments, the secondary battery may include an outer packaging. This outer packaging may be used to encapsulate the electrode assembly and electrolyte described above.

[0113] In some embodiments, the outer packaging of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of the secondary battery can also be a soft pack, such as a pouch. The material of the soft pack can be plastic; examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0114] This application does not impose any particular limitation on the shape of the secondary battery; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 5 This is an example of a square-structured secondary battery 5.

[0115] In some implementations, refer to Figure 6 The outer packaging may include a housing 51 and a cover 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover 53 can be placed over the opening to close the receiving cavity. A positive electrode, a negative electrode, and a separator can be formed into an electrode assembly 52 using a winding or stacking process. The electrode assembly 52 is encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assembly 52. ​​The secondary battery 5 may contain one or more electrode assemblies 52, which can be selected by those skilled in the art according to specific practical needs.

[0116] In some implementations, the secondary batteries can be assembled into a battery module, and the number of secondary batteries contained in the battery module can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery module.

[0117] Figure 7 This is battery module 4, used as an example. (See reference...) Figure 7 In battery module 4, multiple secondary batteries 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other manner. Furthermore, these multiple secondary batteries 5 can be fixed in place using fasteners.

[0118] Optionally, the battery module 4 may also include a housing with a receiving space in which a plurality of secondary batteries 5 are received.

[0119] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0120] Figure 8 and Figure 9 This is battery pack 1 as an example. (See reference...) Figure 8 and Figure 9 The battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box includes an upper body 2 and a lower body 3, with the upper body 2 covering the lower body 3 to form a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0121] In addition, this application also provides an electrical device, which includes at least one of the secondary battery, battery module, or battery pack provided in this application. The secondary battery, battery module, or battery pack can be used as a power source for the electrical device, or as an energy storage unit for the electrical device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0122] As the electrical device, a secondary battery, battery module, or battery pack can be selected according to its usage requirements.

[0123] Figure 10 This is an example of an electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the secondary battery for this device, a battery pack or battery module can be used.

[0124] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a rechargeable battery as their power source.

[0125] Example 1

[0126] Synthesis of high-nickel ternary precursors

[0127] A1: Add 10% pure water to a 100L reactor, start stirring, maintain a constant temperature of 40℃, add NaOH solution until the pH is 12.0, and add ammonia solution until the ammonia concentration is 0.6mol / L (i.e., ammonia value). Add a mixed nickel-cobalt-manganese metal sulfate solution, sodium hydroxide solution, and ammonia solution concurrently to the reactor, keeping the ammonia concentration and pH constant, and continuously react to synthesize the slurry product. The molar ratio of nickel, cobalt, and manganese in the high-nickel ternary precursor is 0.9:0.05:0.05.

[0128] A2: The synthesized high-nickel ternary precursor slurry is centrifuged. During the centrifugation process, it is rinsed twice with deionized water at a volume twice the weight of the slurry. Then, the centrifuged material is dried and sieved to obtain the high-nickel ternary precursor product.

[0129] Synthetic modified high-nickel ternary cathode materials

[0130] B1: Lithium salt-lithium hydroxide, the synthesized high-nickel ternary precursor, and ZrO2 are mixed in a certain proportion in a plow mixer, high-speed mixer, or inclined mixer. The Zr (i.e., element A) doping amount is 3000ppm, the Li / Me molar ratio is 1.1, and Me is the total molar amount of nickel, cobalt, and manganese metals. The mixture is then placed in a kiln for sintering at a sintering temperature T1 of 700℃ and a sintering time T2 of 20h in an O2 atmosphere. The sintering yields a high-nickel ternary cathode material matrix uniformly doped with Na and Zr elements and coated with a first layer of Li2SO4. The Na doping amount is 2000ppm, and the S coating amount in the first layer of Li2SO4 is 3000ppm.

[0131] B2: The high-nickel ternary cathode material matrix synthesized in step B1 is mixed with Co3O4 in a certain proportion (the amount of Co3O4 is weighed according to the predetermined Co element content) in a plow mixer. The amount of Co added is 15000ppm. The mixture is then placed in a kiln for sintering. The sintering temperature T2 is 500℃, the sintering time T2 is 15h, and the sintering atmosphere is O2. The sintering yields a high-nickel ternary cathode material with a second layer of Co compound on its surface.

[0132] B3: The high-nickel ternary cathode material synthesized in step B2 is mixed with Al2O3 in a certain proportion (the amount of Al2O3 is weighed according to the predetermined Al element content for coating) in a plow mixer, high mixer or inclined mixer. The amount of Al (M1 element) added is 2000ppm. The mixture is placed in a kiln for sintering. The sintering temperature T3 is 200℃, the sintering time T3 is 15h, and the sintering atmosphere is O2. The sintering yields a high-nickel ternary cathode material with a third layer of Al compound on the surface.

[0133] Examples 2-5, 7-8

[0134] The difference between Examples 2-5 and 7-8 and Example 1 is that the amount of deionized water used for rinsing in step A2 is different (referring to a multiple relative to the weight of the slurry). At the same time, the alkali metal content, sulfur content, and their molar ratio also change. All other operations and conditions are the same as in Example 1, as detailed in the table below.

[0135] Example Deionized water volume Alkali metal content / ppm S content / ppm Alkali metal / S (molar ratio) 1 2 times 2000 3000 0.93 2 0 6000 7000 1.19 3 0.5 times 5000 5000 1.39 4 1x 3500 4200 1.16 5 3 times 500 1000 0.70 7 7 times 75 150 0.70 8 5 times 100 200 0.70

[0136] Example 6

[0137] The difference between Example 6 and Example 5 is that the type of alkali metal used for doping is different, and the corresponding doping amount, S element content, and molar ratio of alkali metal to S also change. All other operations and conditions are the same as in Example 5, as detailed in the table below.

[0138]

[0139]

[0140] Examples 9-13

[0141] The difference between Examples 9-13 and Example 1 is that the pH value and ammonia value in step A1 are different. All other operations and conditions are the same as in Example 1, as detailed in the table below.

[0142] Example pH value Ammonia value (g / L) 1 12 0.6 9 12.2 0.8 10 11.7 0.5 11 11.4 0.3 12 11 0.2 13 10.8 0.1

[0143] Example 14

[0144] The difference between Example 14 and Example 1 is that the amount of pure water (i.e., the base liquid) added in step A1 is different, the reaction temperature is different, and the alkali metal content and S element content also change. The rest of the operations and conditions are the same as in Example 1, as detailed in the table below.

[0145] Example base liquid Step A1 Temperature / °C Alkali metal content / ppm S content / ppm 1 10％ 40 2000 3000 14 40％ 75 1800 2700

[0146] Examples 15-16

[0147] The difference from Example 1 is that the type of alkali metal is different, but it is added in the form of hydroxide, and the molar ratio of the alkali metal to S also changes. All other operations and conditions are the same as in Example 1, as detailed in the table below.

[0148] Example Alkali metal elements Alkali metal / S (molar ratio) 1 Na 0.93 15 K 1.23 16 Cs 0.36

[0149] Examples 17-18

[0150] The difference from Example 1 is that the total molar ratio of lithium to nickel, cobalt and manganese is different, that is, the Li / Me molar ratio is different. All other operations and conditions are the same as in Example 1, as detailed in the table below.

[0151] Example Li / Me molar ratio 1 1.1 17 1 18 0.9

[0152] Examples 19-26

[0153] The difference from Example 1 is that the operating conditions in step B1 are different (Li / Me molar ratio, sintering temperature, time, type and content of element A, etc.). Element A is added in the form of oxide. The other operations and conditions are the same as in Example 1, as detailed in the table below.

[0154]

[0155]

[0156] Examples 27-31

[0157] The difference from Example 1 is that the operating conditions in step B2 are different (sintering temperature, time, cobalt content, etc.). All other operations and conditions are the same as in Example 1, as detailed in the table below.

[0158] Example T2 / ℃ Time 2 / h Co / ppm 1 500 15 15000 27 400 15 15000 28 700 10 15000 29 800 5 15000 30 900 15 15000 31 500 15 500

[0159] Examples 32-42

[0160] The difference from Example 1 is that the Co source or Co content in step B2 is different, or the operating conditions in step B3 are different (sintering temperature, time, type and content of M1 element, etc.). M1 element is added in the form of oxide in all cases. The other operations and conditions are the same as in Example 1, as detailed in the table below.

[0161]

[0162]

[0163] Example 43

[0164] The only difference from Example 1 is that lithium hydroxide is replaced with lithium fluoride (LiF), while all other operations and conditions are the same as in Example 1.

[0165] Comparative Example 1

[0166] Unlike Example 1, step A2 in the synthesis process of the high-nickel ternary precursor material is as follows:

[0167] After centrifuging the slurry in step A2, before the drying step, a washing and centrifugation process is added to the slurry using a 0.05–1 mol / L NaOH solution. The washing time is 0.5–5 h and the washing temperature is 45–80 °C.

[0168] In step B1 of the cathode material synthesis process, the Na doping amount of the high-nickel ternary cathode material is reduced to 50 ppm, and the S coating amount in the first coating layer Li2SO4 is reduced to 100 ppm. The rest is the same as in Example 1.

[0169] Comparative Example 2

[0170] Unlike Example 1, step A2 in the synthesis process of the high-nickel ternary precursor material is as follows:

[0171] After centrifuging the slurry in step A2, before the drying step, a washing and centrifugation process is added to the slurry using a 0.05–1 mol / L NaOH solution. The washing time is 0.5–5 h and the washing temperature is 45–80 °C.

[0172] In step B1 of the cathode material synthesis process, an additional portion of Na2CO3 is added to the mixture for dry mixing and sintering doping, so that the Na doping amount of the high-nickel ternary cathode material is kept at the same level as in Example 1, up to 2000ppm. An additional portion of Li2SO4 is added to the mixture for dry mixing and sintering coating, so that the S coating amount in the first coating layer Li2SO4 is kept at the same level as in Example 1, up to 3000ppm. Everything else is the same as in Example 1.

[0173] Comparative Example 3

[0174] Unlike Example 1, step A2 in the synthesis process of the high-nickel ternary precursor material is as follows:

[0175] The lithium salt in step B1 is replaced with aluminum oxide, and the total molar ratio of aluminum to nickel, cobalt and manganese is kept the same as in Example 1.

[0176] Other conditions are the same as in Example 1.

[0177] The powder particle size and powder compaction at 5 tons of the positive electrode materials obtained in all the above examples and comparative examples were tested, and coin cells were fabricated using them. Their initial discharge capacity and first-time efficiency were measured at 0.1C. Full cells were also fabricated using them, and their full capacity was tested at 1 / 3C, followed by cycling at 25°C and 1C / 1C at 25°C, cycling at 45°C and 1C / 1C at 45°C, and gas expansion tendency at 70°C for 30 days. The test methods for each performance are as follows.

[0178] Particle size testing method:

[0179] The test method for volumetric particle size distribution is as follows: refer to GB / T19077-2016 / ISO 13320:2009 Particle size distribution laser diffraction method, using Malvern 2000 equipment. Take a clean beaker, add an appropriate amount of the sample to be tested to an opacity of 8%–12%, add 20 ml of deionized water, and simultaneously sonicate externally for 5 minutes. Turn on the particle size analyzer to start the test, and the test result is expressed as (Dv90-Dv10) / Dv50.

[0180] Powder compaction density under 5 tons of pressure

[0181] First, a compaction density test method is used to apply external force to the particles under pressure, and the original powder and the compressed powder are stored in separate bags. Second, the two bags of powder are sent to a laser particle size analyzer for testing, and the output index is Dv1. Then, the data is substituted into the fragmentation rate expression ΔDv1 / Dv1=[Dv1(before compression)-Dv1(after compression)] / Dv1(before compression) to calculate the corresponding value. The compaction density test method includes compacting the sample in a specific mold with a pressure of 5 tons to obtain the thickness, and calculating the compaction density using ρc=m / V=m / (S*H), where m is the weight of the material, S is the powder area, and H is the powder height.

[0182] Fabrication of coin cells:

[0183] The positive electrode active material, PVDF, and conductive carbon are added to a certain amount of NMP in a ratio of 90:5:5. The mixture is stirred in a drying room to form a slurry. The slurry is then coated onto aluminum foil, dried, and cold-pressed to form a positive electrode sheet. A lithium sheet is used as the negative electrode. The electrolyte is 1 mol / L LiPF6 / (EC+DEC+DMC) with a volume ratio of 1:1:1. The mixture is then assembled into a coin cell in a coin cell box.

[0184] Initial capacitance test method for coin cells:

[0185] At 2.8–4.3V, charge at 0.1C to 4.3V, then charge at 4.3V at a constant voltage until the current is ≤0.05mA, and let stand for 2 minutes. The charging capacity at this time is recorded as C0. Then discharge at 0.1C to 2.8V. The discharge capacity at this time is the initial specific capacity, recorded as D0. The first efficiency is D0 / C0*100%. Figure 2 The first charge-discharge curves of the coin cell fabricated from the high-nickel cathode material of Example 1 are listed. The coin cell capacity tested in the table is D0.

[0186] Preparation of full cells:

[0187] Modified high-nickel cathode material, used as the positive electrode active material, is thoroughly mixed with conductive agent acetylene black and binder polyvinylidene fluoride (PVDF) in an N-methylpyrrolidone solvent system at a weight ratio of 94:3:3. This mixture is then coated onto aluminum foil, dried, and cold-pressed to obtain the positive electrode sheet. Anode active materials, including artificial graphite, hard carbon, conductive agent acetylene black, binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC), are thoroughly mixed in a deionized water solvent system at a weight ratio of 90:5:2:2:1. This mixture is then coated onto copper foil, dried, and cold-pressed to obtain the negative electrode sheet. A porous PE polymer film is used as the separator. The positive electrode sheet, separator, and negative electrode sheet are stacked sequentially, with the separator positioned between the positive and negative electrodes for isolation. The stacked sheets are then wound to obtain the bare cell. The bare cell is placed in an outer packaging, injected with the prepared basic electrolyte, and sealed to obtain the full battery.

[0188] All-electric initial capacitance test method:

[0189] Under a constant temperature of 25℃, after standing for 5 minutes, discharge at 1 / 3C to 2.8V, stand for 5 minutes, charge at 1 / 3C to 4.25V, and then charge at 4.25V at a constant voltage until the current is ≤0.05mA. After standing for 5 minutes, the charging capacity at this point is recorded as C0. Then discharge at 1 / 3C to 2.8V, and the discharge capacity at this point is the initial specific capacity, recorded as D0. The first efficiency is D0 / C0*100%. The 1 / 3C total capacity tested in the table is D0.

[0190] All-electric 25 / 45℃ cycle performance test:

[0191] Under constant temperature conditions of 25℃ or 45℃, and at a voltage range of 2.8~4.25V, charge at 1C to 4.25V, then charge at 4.25V with constant voltage until the current is ≤0.05mA, let stand for 5 minutes, and then discharge at 1C to 2.8V. The capacity is recorded as D. n (n=0,1,2……), repeat the above process 300 times, and calculate the capacity retention rate after 300 cycles as (D0-D300) / D0*100%. Figure 3 Cycle curves of batteries made from the materials of Comparative Example 1 and Example 1 are listed.

[0192] All-electric 70℃ expansion test:

[0193] Storage at 70℃ and 100% SOC: Measure cell OCV, IMP, and volume (by water displacement method) before, during, and after storage. Test cell residual capacity and reversible capacity at the end of storage. Remove cells from the furnace every 48 hours, let stand for 1 hour, and then test OCV and IMP. After cooling to room temperature, test cell volume using the water displacement method. End testing after 30 days of storage, or stop storage if volume expansion exceeds 50%. Protection voltage range: 2.7-4.3V, nominal capacity 2.25Ah. Figure 4 The gas expansion curves of full cells made from the materials of Comparative Example 1 and Example 1 at 70°C are listed.

[0194] Comparison table of performance data of synthetic samples from comparative examples and embodiments

[0195]

[0196] Test results show that:

[0197] Compared with Comparative Example 1, the precursor of the present invention does not require washing with an alkali metal hydroxide solution, thus retaining a certain amount of alkali metal ions and sulfate ions uniformly coated on the precursor surface. Through sintering of the cathode material, alkali metal ions can be uniformly doped at the lithium sites in the bulk phase of the high-nickel ternary cathode material, effectively expanding and stabilizing the lithium ion transport channels, improving the material's capacity and cycle performance. Simultaneously, a first layer of Li₂SO₄ can be uniformly coated on the surface of the high-nickel ternary cathode material. Under long-cycle and high-temperature storage conditions, the coated Li₂SO₄ is not easily soluble in the electrolyte and does not undergo side reactions with the electrolyte, significantly improving the long-term cycle performance and storage performance of the high-nickel ternary cathode material. Furthermore, compared with conventional precursor synthesis processes, the present invention eliminates the alkaline washing step, reducing process costs.

[0198] Comparing Example 1 and Comparative Example 2, Comparative Example 2, based on Comparative Example 1, involves adding Na2CO3 and Li2SO4 additives during the first sintering step of the cathode material through pyrometallurgical dry mixing and sintering. This ensures that the amount of Na doping and the amount of lithium sulfate coating are the same as in Example 1. However, due to the poor uniformity of dry mixing, the uniformity of Na doping and Li2SO4 coating is also poor. Furthermore, the dry sintering coating of Li2SO4 is not easily applied to the material, resulting in very poor coating uniformity. Consequently, the performance indicators are significantly worse than those in Example 1.

[0199] Comparing Examples 1 to 5 with Examples 7-8, the amount of deionized water used to rinse the centrifuged slurry in precursor synthesis step A2 significantly affects the performance of the cathode material. Excessive deionized water rinsing results in very few residual sodium and sulfate ions on the precursor surface, hindering the improvement of structural and interfacial stability. Conversely, insufficient or no deionized water rinsing leads to excessive residual sodium and sulfate ions on the precursor surface, resulting in too many sodium and sulfate ion impurities on the surface of the high-nickel ternary cathode material, affecting its energy density and long-term performance.

[0200] Comparing Examples 1, 20, and 21 with Examples 19 and 22, when the first sintering temperature is too low, the high-nickel ternary cathode material will not crystallize perfectly, resulting in poor performance of the material. When the first sintering temperature is too high, the high-nickel ternary cathode material will be over-sintered, causing structural damage and deteriorating performance.

[0201] Comparing Examples 1 and 25-26, it is evident that excessive or insufficient doping of element A during the first sintering process can negatively impact the material's performance. Insufficient doping of element A results in minimal improvement in the structural stability of the high-nickel ternary material, negatively affecting its long-term performance and storage capacity. Conversely, excessive doping of element A leads to residual inactive dopant compounds, which in turn negatively impacts the material's capacity and long-term performance.

[0202] Comparing Example 1 with Examples 27 and 30, excessively high or low temperatures during the second Co coating significantly affect the material's performance. When the coating temperature is too low, it hinders the adhesion of the Co compound to the surface and the reaction between residual lithium and the Co compound, resulting in excessively high residual lithium levels. This also reduces the material's capacity, interfacial stability, and electrochemical performance. Conversely, when the coating temperature is too high, the Co compound is directly incorporated into the particles, failing to achieve the desired effect of improving interfacial stability and leading to poor capacity and long-term performance.

[0203] Comparing Example 1 with Examples 31 and 35, when the amount of Co compound coating is small, it cannot achieve the effect of improving interface stability. When the amount of Co compound coating is too large, the surface of the high-nickel ternary material will have more inactive residual Co compounds, which will reduce the material's capacity and long-term performance.

[0204] Comparing Example 1 with Examples 36 and 39, when the coating temperature of the M1-containing compound is too low in the third coating, it is not conducive to the coating effect and firmness of the M1-containing compound. When the coating temperature is too high, the M-containing compound will penetrate into the particulate phase of the material, which is not conducive to improving the interface stability.

[0205] Comparing Example 1 with Examples 40 and 41, when the amount of M-containing compound coating is small, it cannot achieve the effect of improving interface stability; when the amount of M-containing compound coating is excessive, it will reduce the material's capacity and long-term performance.

[0206] Comparing Example 1 and Example 13, if the pH value and ammonia value of the precursor synthesis process are too low, the particle size distribution of the synthesized precursor will be very narrow, and the compaction of the sintered high-nickel ternary cathode material will be low, which will reduce the energy density of the battery cell.

[0207] Comparing Example 1 and Example 9, if the pH value and ammonia value of the precursor synthesis process are too high, the particle Dv50 will be lower, the material compaction will be reduced, and the precursor crystal structure will be poor, which will affect the performance of the cathode material.

[0208] Compared with Comparative Examples 1-42 and Comparative Examples 1-3, the modified high-nickel ternary cathode material synthesized using the innovative method of this invention can reduce process costs and significantly improve the performance of high-nickel ternary materials.

[0209] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A modified high-nickel ternary cathode material, characterized in that, It includes a substrate and a first covering layer, a second covering layer, and a third covering layer sequentially covering the substrate; The substrate includes Li 1.1-a M a (Ni b Co c Mn d ) 1-e A e O2E f And 0.01≤a≤0.2, 0.8≤b≤1, 0.01≤c≤0.2, 0.01≤d≤0.2, 0<e≤0.05, 0≤f≤0.1; wherein M is selected from one or more of the alkali metal elements Na, K, Rb, and Cs, A is selected from one or more of Al, Mg, Zr, Ti, W, Y, B, Co, Nb, Mo, Sb, and Sr, and E is selected from one or more of F, Cl, Br, and I; The first coating layer includes Li2SO4, the second coating layer includes a cobalt-containing compound, and the third coating layer includes a compound containing M1; wherein M1 includes one or more of Al, Ti, B, W, Nb, and Sb.

2. The modified high-nickel ternary cathode material as described in claim 1, characterized in that, The molar ratio of alkali metal M to S is (0.2~4.2):

1.

3. The modified high-nickel ternary cathode material as described in claim 2, characterized in that, The molar ratio of alkali metal M to sulfur is (0.36~1.39):

1.

4. The modified high-nickel ternary cathode material as described in claim 1 or 2, characterized in that, (1.1-a):(b+c+d)=0.9~1.

1.

5. The modified high-nickel ternary cathode material as described in claim 1 or 2, characterized in that, Based on the modified high-nickel ternary cathode material, the content of alkali metal M element is 100~5000ppm.

6. The modified high-nickel ternary cathode material as described in claim 5, characterized in that, Based on the modified high-nickel ternary cathode material, the content of alkali metal M element is 500~2000ppm.

7. The modified high-nickel ternary cathode material as described in claim 1 or 2, characterized in that, Based on the modified high-nickel ternary cathode material, the sulfur content is 200~5000ppm.

8. The modified high-nickel ternary cathode material as described in claim 1 or 2, characterized in that, Based on the modified high-nickel ternary cathode material, the sulfur content is 1000~3000ppm.

9. The modified high-nickel ternary cathode material as described in claim 1 or 2, characterized in that, Based on the modified high-nickel ternary cathode material, the cobalt content in the second coating layer is 1000~20000ppm.

10. The modified high-nickel ternary cathode material as described in claim 9, characterized in that, Based on the modified high-nickel ternary cathode material, the cobalt content in the second coating layer is 5000~15000ppm.

11. The modified high-nickel ternary cathode material as described in claim 1 or 2, characterized in that, Based on the modified high-nickel ternary cathode material, the content of M1 element is 100~5000ppm; And / or, Based on the modified high-nickel ternary cathode material, the content of element A is 100~8000ppm.

12. The modified high-nickel ternary cathode material as described in claim 11, characterized in that, Based on the modified high-nickel ternary cathode material, the content of M1 element is 500~2000ppm; And / or, Based on the modified high-nickel ternary cathode material, the content of element A is 1000~5000ppm.

13. The modified high-nickel ternary cathode material as described in claim 1, characterized in that, The volumetric particle size Dv50 of the modified high-nickel ternary cathode material is 3~20μm.

14. The modified high-nickel ternary cathode material as described in claim 13, characterized in that, The volumetric particle size Dv50 of the modified high-nickel ternary cathode material is 3~15μm.

15. The modified high-nickel ternary cathode material as described in claim 1 or 13, characterized in that, The particle size distribution of the modified high-nickel ternary cathode material has a particle size distribution with a diameter (Dv90-Dv10) / Dv50 ≥ 1.

0.

16. The modified high-nickel ternary cathode material as described in claim 15, characterized in that, The particle size distribution of the modified high-nickel ternary cathode material has a particle size distribution with a diameter (Dv90-Dv10) / Dv50 ≥ 1.

2.

17. The modified high-nickel ternary cathode material as described in claim 1 or 13, characterized in that, The compaction density of the modified high-nickel ternary cathode material under 5 tons of pressure is ≥3.45 g / cc.

18. A method for preparing a modified high-nickel ternary cathode material, characterized in that, Includes the following steps: The sulfates of nickel, cobalt, and manganese are reacted with an alkaline solution in an alkaline environment to form a high-nickel ternary precursor slurry; the alkaline solution includes a hydroxide solution of an alkali metal M, wherein M includes one or more of Na, K, Rb, and Cs; The high-nickel ternary precursor slurry is dried to obtain the precursor product; The lithium salt, the precursor product, the compound containing element A, and the compound containing element E are mixed and sintered for the first time to obtain a high-nickel ternary cathode material matrix doped with alkali metal, element A, and element E and coated with a first coating layer. Then, the high-nickel ternary cathode material matrix is ​​mixed with a cobalt-containing compound and sintered a second time, followed by a mixture with a M1-containing compound and sintered a third time to obtain a modified high-nickel ternary cathode material. The modified high-nickel ternary cathode material includes a substrate and a first coating layer, a second coating layer, and a third coating layer sequentially coated on the substrate; The substrate includes Li 1.1-a M a (Ni b Co c Mn d ) 1-e A e O2, and 0.01≤a≤0.2, 0.8≤b≤1, 0.01≤c≤0.2, 0.01≤d≤0.2, 0<e≤0.05; wherein M is selected from one or more of the alkali metal elements Na, K, Rb, and Cs, and A is selected from one or more of Al, Mg, Zr, Ti, W, Y, B, Co, Nb, Mo, Sb, and Sr; The first coating layer includes Li2SO4, the second coating layer includes a cobalt-containing compound, and the third coating layer includes a compound containing M1; wherein M1 includes one or more of Al, Ti, and B.

19. The preparation method according to claim 18, characterized in that, The pH value of the alkaline solution environment is controlled by ammonia water, and the pH value is between 11 and 12.

20. The preparation method according to claim 19, characterized in that, The pH value is 11.1~11.

7.

21. The preparation method according to claim 18, characterized in that, The ammonia concentration in the alkaline solution environment is 0.2~0.6 mol / L.

22. The preparation method according to claim 21, characterized in that, The ammonia concentration in the alkaline solution environment is 0.3~0.5 mol / L.

23. The preparation method according to claim 18, characterized in that, Before the drying process, the high-nickel ternary precursor slurry is centrifuged and rinsed with water in sequence.

24. The preparation method according to claim 23, characterized in that, The weight of water used for rinsing is 0.5 to 5 times the weight of the high-nickel ternary precursor slurry.

25. The preparation method according to claim 24, characterized in that, The weight of water used for rinsing is 1 to 3 times the weight of the high-nickel ternary precursor slurry.

26. The preparation method according to claim 18, characterized in that, The conditions for the first sintering are: sintering temperature of 700~950℃, sintering time of 10~20h, and sintering atmosphere of air or O2.

27. The preparation method according to claim 18, characterized in that, The conditions for the second sintering are: sintering temperature of 500~800℃, time of 5~15h, and sintering atmosphere of air or O2.

28. The preparation method according to claim 27, characterized in that, The conditions for the second sintering are: sintering temperature of 550~750℃ and time of 5~10h.

29. The preparation method according to claim 18, characterized in that, The conditions for the third sintering are: sintering temperature of 200~500℃, sintering time of 5~15h, and sintering atmosphere of air or O2.

30. The preparation method according to claim 29, characterized in that, The conditions for the third sintering are: sintering temperature of 200~400℃ and sintering time of 5~10h.

31. The preparation method according to claim 18, characterized in that, The lithium salt includes one or a mixture of two of lithium carbonate and lithium hydroxide; And / or, The cobalt-containing compounds include one or more of the following: Co3O4, Co(OH)2, CoO, CoOOH, cobalt acetate, cobalt oxalate, and CoCO3. And / or, The compounds containing element M1 include one or more of the following: oxides, hydroxides, and carbonates of M1. And / or, The compounds containing element A include one or more of oxides, hydroxides, and carbonates of A; And / or, The compounds containing element E include one or more of metallic compounds and non-metallic compounds containing element E, and the element E includes one of F, Cl, Br or I.

32. The preparation method according to claim 18, characterized in that, The doping amount of the compound containing element M1 is 100~5000 ppm based on the mass of element M1; And / or, The doping amount of the compound containing element A is 100~8000 ppm based on the mass of element A.

33. The preparation method according to claim 32, characterized in that, The doping amount of the compound containing element M1 is 500~2000 ppm based on the mass of element M1. And / or, The doping amount of the compound containing element A is 1000~5000 ppm based on the mass of element A.

34. The preparation method according to claim 18, characterized in that, Before the reaction, 10-40% of the volume of water in the reactor is added as a base liquid.

35. A secondary battery comprising the modified high-nickel ternary cathode material according to any one of claims 1 to 17, or comprising the modified high-nickel ternary cathode material obtained by the preparation method according to any one of claims 18 to 34.

36. A battery module comprising the secondary battery according to claim 35.

37. A battery pack comprising the battery module according to claim 36.

38. An electrical device comprising at least one of the secondary battery of claim 35, the battery module of claim 36, or the battery pack of claim 37.

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