Active materials and their preparation processes, positive electrode sheets and their preparation processes, and batteries

Abstract

This application discloses an active material and its preparation process, a positive electrode sheet and its preparation process, and a battery, relating to the field of positive electrode material technology. The active material includes a matrix and a coating layer covering the surface of the matrix. The matrix includes a ternary material, and the coating layer includes a polyanionic compound. In this application's technical solution, by constructing a polyanionic compound coating layer on the surface of the ternary material, the structural and interfacial stability of the positive electrode material is improved from the source. This helps to make the degradation (including capacity decay and internal resistance increase) of the battery cell containing this active material more slow and uniform, thereby improving the degradation consistency of each battery cell and making the capacity decay and internal resistance change curves of all cells in the module highly synchronized.

Description

Technical Field

[0001] This application relates to the field of cathode material technology, specifically to an active material and its preparation process, a cathode electrode and its preparation process, and a battery. Background Technology

[0002] In related technologies, the methods to improve module voltage drop are mostly related to grouping and charging / discharging conditions, which are mostly improvements at the module level and the outer layer of the cell. These improvement methods can only improve a single grouping method and cannot address all grouping methods, so the improvement effect is limited. Summary of the Invention

[0003] This application provides an active material and its preparation process, a positive electrode sheet and its preparation process, and a battery, aiming to solve the problem of limited improvement effect due to the inability to address all matching methods.

[0004] According to a first aspect of this application, an active material is provided, comprising a matrix and a coating layer covering the surface of the matrix, wherein the matrix comprises a ternary material and the coating layer comprises a polyanionic compound.

[0005] In some embodiments of this application, the ternary material includes polycrystalline ternary materials and / or monocrystalline ternary materials; and / or, Polyanionic compounds include at least one of lithium aluminum titanium phosphate, lithium titanium phosphate, and lithium titanium silicon phosphate; and / or, The thickness of the coating layer is 60nm-80nm.

[0006] This configuration allows for targeted mitigation of each material's weaknesses by constructing a polyanionic compound coating layer on both surfaces: for polycrystalline materials, the coating layer can fill surface cracks and suppress side reactions at grain boundaries; for monocrystalline materials, surface integrity is primarily protected by isolating the electrolyte from contact.

[0007] With this configuration, lithium aluminum titanium phosphate (LATP) is a typical polyanionic compound. The LATP coating layer works synergistically to suppress side reactions, maintain interfacial ion conductivity, and enhance structural support, fundamentally delaying the degradation of ternary materials. Lithium titanium phosphate provides stable three-dimensional ion transport channels, and its titanium-oxygen octahedral structure is less prone to lattice distortion during high-temperature cycling. Lithium titanium silicon phosphate, upon the introduction of silicon, forms a denser network structure, preventing electrolyte penetration while maintaining good lithium-ion conductivity.

[0008] This configuration, by precisely controlling the thickness of the coating layer, achieves an optimal balance between protective effect and ion transport kinetics. Within this range, the coating layer is sufficient to form a continuous, dense protective layer that blocks electrolyte corrosion and inhibits transition metal dissolution, while its thickness is insufficient to cause significant additional resistance to lithium-ion migration.

[0009] In some embodiments of this application, lithium aluminum titanium phosphate includes Li 1.3 Al 0.3 Ti 1.7 (PO4)3 and Li 1.4 Al 0.4 Ti 1.6 At least one of (PO4)3; and / or, Polycrystalline ternary materials include LiNi 0.8 Co 0.1 Mn 0.1 O 2、 LiNi 0.85 Co 0.075 Mn 0.075 O2 or LiNi 0.8 Co 0.15 Mn 0.05 O2; and / or, Single-crystal ternary materials include LiNi 0.92 Co 0.03 Mn 0.05 O2, LiNi 0.9 Co 0.05 Mn 0.05 O2 or LiNi 0.88 Co 0.09 Mn 0.03 O2.

[0010] This configuration, choosing these three LATP compounds, is based on a comprehensive consideration of the coating material's ion conductivity, electrochemical stability, and physical barrier function. Furthermore, they can work synergistically to construct a stable interface layer at the microscopic level that can both rapidly conduct lithium ions and isolate side reactions.

[0011] With this setting, select LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811) is a representative of polycrystalline ternary materials because its high nickel content improves its high specific capacity.

[0012] This configuration is suitable for LiNi. 0.92 Co 0.03 Mn 0.05 For O2 (ultra-high nickel single crystal NCM), its single crystal structure reduces grain boundary problems and has higher bulk structural stability. However, its extremely high nickel content results in a large amount of residual lithium (such as Li2CO3 and LiOH) on the surface, and the surface Ni³ + / 4+ It has high activity and readily undergoes vigorous redox reactions with the electrolyte.

[0013] In some embodiments of this application, the substrate has multiple forms, including a first substrate made of a polycrystalline ternary material and a second substrate made of a single-crystal ternary material, wherein the surfaces of both the first and second substrates are covered with a coating layer; wherein... The mass ratio of the first matrix to the second matrix is ​​(7:3) - (9:1).

[0014] With this configuration, when both materials coexist in the electrode at an optimized ratio, the polyanion coating layer compensates for their respective weaknesses: for polycrystalline materials, it suppresses side reactions at grain boundaries and the dissolution of transition metals; for monocrystalline materials, it reduces surface side reactions and excessive CEI growth. This makes the degradation rates and modes of different matrix materials more similar, reducing the dependence on the precision of cell selection and grouping, and fundamentally improving the overall lifespan and reliability of the battery system.

[0015] In some embodiments of this application, the median grain size of the polycrystalline ternary material is 9 μm-11 μm; and / or, The median particle size of the single-crystal ternary material is 2μm-6μm.

[0016] By precisely controlling the median particle size of the polycrystalline ternary material within this range, its tap density and electrode processing performance can be optimized, while ensuring sufficient specific surface area to facilitate uniform coverage of the coating layer.

[0017] This configuration controls the median particle size of the single-crystal ternary material within this range, which helps to balance its specific surface area and lithium-ion diffusion path length while maintaining high structural stability.

[0018] According to a second aspect of this application, a process for preparing an active substance is also provided, comprising: The polyanionic compound is mixed with the ternary material to obtain a mixture. The mixture is heated in an aerobic environment to obtain an intermediate product; The intermediate product was pulverized to obtain the active substance; among which, Ternary materials are heated in an aerobic environment to form a matrix, while polyanionic compounds are heated in an aerobic environment to form a coating layer.

[0019] This setup allows for a controlled chemical reaction on the surface of the ternary material through a heat treatment process in an aerobic environment, forming a stable matrix structure. Simultaneously, the polyanionic compound pyrolyzes under the same conditions and uniformly coats the matrix surface, forming a dense protective layer.

[0020] In some embodiments of this application, the heating temperature of the mixture is 650°C-750°C; and / or, After pulverizing the intermediate product, the process also includes sieving the pulverized intermediate product to obtain the active substance.

[0021] This configuration allows the ternary material to be fully oxidized within this heating temperature range to form a stable crystal structure, while simultaneously enabling the polyanionic compound to achieve dense encapsulation.

[0022] This setup allows for precise control of the particle size distribution of the active material through a sieving process. Particles within a specific size range are conducive to forming a tightly packed electrode structure, ensuring both high tap density and providing channels for lithium-ion diffusion.

[0023] In some embodiments of this application, the substrate has multiple forms, including a first substrate made of a polycrystalline ternary material and a second substrate made of a single-crystal ternary material, wherein the surfaces of both the first and second substrates are covered with a coating layer; wherein... After mixing polycrystalline ternary materials and monocrystalline ternary materials, a premixed material is obtained; The polyanionic compound is mixed with the premixed material to obtain a mixture.

[0024] This configuration, by introducing a composite matrix structure of polycrystalline and monocrystalline ternary materials, combines the advantages of high specific capacity of polycrystalline materials and structural stability of monocrystalline materials. The grain boundaries between polycrystalline particles provide more lithium-ion migration channels, while monocrystalline particles can suppress grain boundary cracking during cycling.

[0025] According to a third aspect of this application, a positive electrode sheet is also provided, comprising a current collector and a positive electrode material coating coated on the current collector; the positive electrode material coating comprises the active material as described above or the active material prepared by the above-described active material preparation process, a conductive agent, a binder, and a solvent.

[0026] This configuration improves the uniformity and stability of the active material's adhesion to the current collector, thereby enhancing the battery's rate performance and cycle life. Using the aforementioned active material or its specific preparation process can optimize the morphology and particle size distribution of the material particles, reduce agglomeration, and enhance interfacial compatibility with conductive agents and binders.

[0027] In some embodiments of this application, the current collector includes a carbon-coated current collector, the carbon coating of which is made from raw materials composed of acrylic emulsion, deionized water and carbon black.

[0028] This configuration, employing a carbon-coated current collector, with its surface coating composed of acrylic emulsion, deionized water, and carbon black, improves the interfacial contact and conductivity between the current collector and the cathode material coating. The acrylic emulsion acts as a binder, firmly adhering the carbon black particles to the current collector surface, forming a continuous and porous conductive layer. This conductive layer not only reduces the contact resistance between the current collector and the active material, promoting rapid electron transport, but also helps to evenly distribute the current during charging and discharging, reducing the risk of localized overcharging or over-discharging. Simultaneously, the high specific surface area and excellent conductivity of carbon black further enhance the conductive network of the electrode, enabling efficient utilization of the active material.

[0029] In some embodiments of this application, the carbon coating layer comprises a raw material consisting of 20wt%-30wt% acrylic emulsion, 60wt%-75wt% deionized water, and 5wt%-15wt% carbon black; and / or, Carbon black includes at least one of conductive carbon black, furnace black, and acetylene black.

[0030] With this setup, the content of acrylic emulsion is controlled within this range, which ensures that the carbon black particles are evenly dispersed in the carbon coating layer and firmly adhered to the surface of the current collector, while also reducing the risk of decreased coating flexibility or increased internal resistance due to excessive use. The content of deionized water is controlled within this range, which optimizes the rheology of the slurry and ensures the uniformity of the coating process and the drying efficiency. The content of carbon black is controlled within this range, which enables the formation of a continuous conductive network in the electrode and improves the electron conduction efficiency.

[0031] This configuration, using at least one of conductive carbon black, furnace black, or acetylene black, is chosen because these carbon black materials all possess high conductivity and a large specific surface area, enabling the formation of a conductive network within the electrode and improving electron transport efficiency. Conductive carbon black exhibits excellent dispersibility and conductivity, facilitating the formation of a uniform conductive layer; furnace black has a more developed structure, enhancing the mechanical strength and conductivity durability of the carbon coating layer; and acetylene black, due to its high purity and low impurity content, helps reduce side reactions and improve the chemical stability of the battery. By rationally selecting the type of carbon black, the conductivity, adhesion, and durability of the carbon coating layer can be optimized according to specific application requirements, thereby further improving the overall performance and lifespan of the battery.

[0032] In some embodiments of this application, the positive electrode material coating comprises a raw material consisting of 55wt%-70wt% of active material, 0.5wt%-5wt% of conductive material, 1wt%-4wt% of binder and 25wt%-40wt% of solvent.

[0033] With this setup, the active material content is controlled within this range, allowing the electrode to have sufficient energy density and capacity, while also providing adequate space for the conductive agent and binder to construct a stable electrode structure. Within this range, the conductive agent content enables the formation of a continuous and efficient conductive network between the active material particles, reducing electrode internal resistance and improving rate performance. Controlling the binder content within this range ensures a strong bond between the active material and conductive agent particles, as well as between the coating and the current collector. Within this range, the solvent content gives the cathode material slurry suitable viscosity and rheological properties, facilitating uniform coating; its dosage must be precisely controlled to ensure drying efficiency and cathode electrode quality.

[0034] In some embodiments of this application, the conductive agent includes a first solvent, a dispersant, and a conductive substance; and / or, The adhesive includes a second solvent and a binder; and / or, The solvent includes N-methylpyrrolidone.

[0035] This configuration, by designing the conductive agent to consist of a first solvent, a dispersant, and a conductive substance, optimizes the dispersion and conductivity of the conductive agent in the cathode material coating. The first solvent allows the conductive substance and dispersant to mix uniformly and form a stable slurry system; the dispersant, through its surface activity, prevents the conductive substance from agglomerating and promotes its uniform distribution between the active material and the binder; the conductive substance, as the core component, is responsible for constructing continuous electron conduction pathways within the electrode.

[0036] This configuration optimizes the film-forming performance and adhesion of the binder in the cathode material coating. The second solvent fully dissolves or disperses the binder, forming a uniform slurry system that facilitates the coating process. The binder, as a key component, firmly binds the active material, conductive agent, and other components together through physical entanglement or chemical cross-linking between its polymer chains, ensuring a tight adhesion between the coating and the current collector.

[0037] This setup, using N-methylpyrrolidone (NMP) as the solvent, is primarily based on its excellent physicochemical properties and good compatibility with the various components of the electrode slurry. NMP has a high boiling point, strong polarity, and moderate volatility, which can dissolve or disperse binders (such as polymers like PVDF), resulting in a uniform and stable slurry system and reducing component sedimentation or agglomeration.

[0038] In some embodiments of this application, the conductive agent comprises a raw material consisting of 81wt%-84wt% of a first solvent, 5wt%-9wt% of a dispersant, and 10wt%-14wt% of a conductive substance; and / or, The first solvent includes N-methylpyrrolidone; and / or, Dispersants include polyvinylpyrrolidone; and / or, Conductive materials include acetylene black; and / or, The binder comprises a raw material consisting of 90wt%-95wt% of a second solvent and 5wt%-10wt% of a binder substance; and / or, The second solvent includes N-methylpyrrolidone; and / or, The binder material includes polyvinylidene fluoride.

[0039] This configuration allows the components in the conductive agent to work synergistically in a specific ratio: the first solvent at this concentration provides good fluidity and a good dispersion medium, which is beneficial for uniform distribution in subsequent processing; the dispersant at this concentration can prevent the agglomeration of conductive substances and improve the stability of the system; and the content of conductive substances at this concentration can ensure conductivity.

[0040] With this configuration, N-methylpyrrolidone exhibits good solubility and chemical stability, enabling it to disperse active materials and improve the uniformity and consistency of the electrode slurry, thereby enhancing the rate performance and cycle life of the battery.

[0041] This configuration is because polyvinylpyrrolidone, as a highly efficient polymeric dispersant, contains both hydrophilic and hydrophobic groups in its molecular structure. It can adsorb onto the particle surface through steric hindrance, forming a stable protective layer, thereby reducing the van der Waals forces between particles, preventing particle agglomeration and sedimentation, and making the system uniform and stable.

[0042] This configuration can improve the conductivity of the electrode material and enhance the bonding force between the active material and the current collector, thereby improving the rate performance and cycle stability of the battery.

[0043] With this setting, the content of the second solvent within this concentration range can fully dissolve or disperse the binder material, forming a slurry system with suitable viscosity and rheological properties, which facilitates uniform film formation in the coating process; the content of the binder material within this concentration range can ensure sufficient bonding strength.

[0044] With this configuration, N-methylpyrrolidone, as the second solvent, possesses high polarity and solubility, enabling it to dissolve or disperse the binder material and form a uniform and stable slurry system. Its moderate boiling point and evaporation rate contribute to the uniform evaporation of the solvent during the coating process.

[0045] This design gives polyvinylidene fluoride (PVDF) excellent chemical and thermal stability, enabling it to withstand electrochemical corrosion and temperature changes in the battery operating environment, thus ensuring the integrity of the electrode structure during long-term cycling. The fluorine atoms in its molecular chain endow the material with strong polarity and high bonding strength, which can fix the active materials and conductive agents, preventing electrode components from detaching during charging and discharging.

[0046] According to the fourth aspect of this application, a process for preparing a positive electrode sheet is also provided, for preparing the above-mentioned positive electrode sheet, comprising: Active material, conductive agent, binder and solvent are mixed to obtain positive electrode material slurry; The cathode material slurry is coated onto the current collector to obtain the intermediate; The intermediate is dried to obtain the positive electrode sheet; wherein... The cathode material slurry forms a cathode material coating after drying.

[0047] According to a fifth aspect of this application, a battery is also proposed, comprising the aforementioned positive electrode; or, The positive electrode sheet prepared by the above-mentioned positive electrode sheet preparation process.

[0048] This setup, pre-mixing the active material, conductive agent, binder, and solvent into a slurry, allows for uniform dispersion of each component in the solvent, forming a stable suspension system. This reduces the risk of component segregation or agglomeration after coating, which could affect the consistency of the electrode's electrochemical performance. Coating the slurry onto the current collector allows for precise control of the coating's thickness and areal density, ensuring uniformity in battery capacity and rate performance. The subsequent drying process removes the solvent, allowing the binder to solidify and form a porous electrode structure tightly bonded to the current collector, providing stable channels for lithium-ion migration and electron conduction.

[0049] In the technical solution of this application, by constructing a polyanionic compound coating layer on the surface of the ternary material, the structural stability and interface stability of the cathode material are improved from the source. This is beneficial to make the degradation (including capacity degradation and internal resistance growth) of the cell with the active material more slow and uniform, thereby improving the degradation consistency of each cell and making the capacity degradation and internal resistance change curves of all cells in the module highly synchronized. Detailed Implementation

[0050] The technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0051] This application provides an active material and its preparation process, a positive electrode sheet and its preparation process, and a battery. These are described in detail below. It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". The terms first, second, third, etc., are used merely as illustrative and do not impose numerical requirements or establish an order. Various embodiments of the present invention may exist in a range format; it should be understood that the description in a range format is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the corresponding ranges, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any referenced number (fraction or integer) within the indicated range.

[0052] According to a first aspect of this application, an active material is provided, comprising a matrix and a coating layer covering the surface of the matrix, wherein the matrix comprises a ternary material and the coating layer comprises a polyanionic compound.

[0053] In the technical solution of this application, by constructing a polyanionic compound coating layer on the surface of the ternary material, the structural stability and interface stability of the cathode material are improved from the source. This is beneficial to make the degradation (including capacity degradation and internal resistance growth) of the cell with the active material more slow and uniform, thereby improving the degradation consistency of each cell and making the capacity degradation and internal resistance change curves of all cells in the module highly synchronized.

[0054] It can be explained that the meaning of polyanionic compounds is that they are polyanionic groups (e.g., (PO4)3) bonded together by strong covalent bonds. - (SiO4) 4- (SO4)² - Compounds composed of PO, Si-O, and SO groups and metal cations. These polyanionic groups form a stable spatial network framework structure through strong PO, Si-O, and SO covalent bonds, exhibiting high thermal and electrochemical stability. Coating the surface of ternary materials with these compounds can isolate the ternary materials from electrolyte corrosion, inhibit the dissolution of transition metal ions, and reduce interfacial side reactions under high voltage, thereby improving the interfacial stability of the materials.

[0055] In some embodiments of this application, the ternary material includes polycrystalline ternary materials and / or monocrystalline ternary materials.

[0056] This configuration, for polycrystalline ternary materials, whose particles consist of multiple grains with numerous grain boundaries, makes them prone to grain boundary cracking and side reactions during cycling, leading to accelerated structural degradation. In contrast, monocrystalline ternary materials, lacking grain boundaries, have a more stable bulk structure but higher surface activity, making them susceptible to side reactions with the electrolyte. For polycrystalline materials, the coating layer can fill surface cracks and suppress side reactions at grain boundaries; for monocrystalline materials, surface integrity is primarily protected by isolating them from electrolyte contact.

[0057] In addition, in other embodiments of this application, the ternary material also includes at least one of a core-shell structure, a concentration gradient structure, and a lithium-rich manganese-based ternary material.

[0058] With this configuration, the polyanionic compound coating technology of this application can be adapted to ternary materials with various structures, such as core-shell and concentration gradient structures.

[0059] In some embodiments of this application, the polyanionic compound includes at least one of lithium aluminum titanium phosphate, lithium titanium phosphate, and lithium titanium silicon phosphate.

[0060] With this configuration, lithium aluminum titanium phosphate (LATP) is a typical polyanionic compound, containing (PO4)³ in its structure. - The polyanionic groups form a stable three-dimensional framework. This structure endows it with extremely high lithium-ion conductivity and excellent thermal stability. When coated on the surface of ternary materials, the LATP layer not only acts as a physical barrier to isolate the electrolyte, but its rapid ion conduction characteristics also allow for the smooth migration of lithium ions at the interface, thereby improving interface stability without negatively impacting the battery's rate performance. Furthermore, the Ti in LATP... 4+ Ions are chemically stable and do not easily change their valence, while Al³⁺ + Ion doping further stabilizes its crystal structure, enabling the coating layer to remain stable under high voltage and continue to provide protection. Therefore, the LATP coating layer can fundamentally delay the degradation of ternary materials by suppressing side reactions, maintaining interfacial ion conductivity, and enhancing structural support. Lithium titanium phosphate provides a stable three-dimensional ion transport channel, and its titanium-oxygen octahedral structure is less prone to lattice distortion during high-temperature cycling. Lithium titanium silicon phosphate forms a denser network structure after the introduction of silicon, blocking electrolyte penetration while maintaining good lithium-ion conductivity.

[0061] In some embodiments of this application, the thickness of the coating layer is 60nm-80nm.

[0062] This design, through precise control of the coating thickness, achieves an optimal balance between protective effect and ion transport kinetics. Within this range, the coating is sufficient to form a continuous, dense protective layer, blocking electrolyte corrosion and inhibiting transition metal dissolution, while its thickness is insufficient to create significant additional resistance to lithium-ion migration. This optimized thickness design ensures that capacity decay and internal resistance growth of the cell are uniformly suppressed during long-term cycling.

[0063] In some embodiments of this application, lithium aluminum titanium phosphate includes Li 1.3 Al 0.3 Ti 1.7 (PO4)3 and Li 1.4 Al 0.4 Ti 1.6 At least one of (PO4)3.

[0064] With this setup, Li 1.3 Al 0.3 Ti 1.7 (PO4)3 is a typical NASICON-type structural material. In its structure, [AlO6] and [TiO6] octahedra are connected to [PO4] tetrahedra through vertex oxygen atoms, forming a stable three-dimensional framework and spacious lithium-ion migration channels. A suitable amount of Al³⁺... + Doping and substituting Ti 4+ On the one hand, the introduction of additional lithium ions improves the bulk ionic conductivity of the material; on the other hand, the lithium vacancies generated by the charge compensation effect further promote lithium ion migration, resulting in a high lithium-ion conductivity (approximately 10⁻⁶) even at room temperature. - (On the order of ³ S / cm). This high ionic conductivity ensures that the coating does not impede the battery's rate performance. Li1.4Al0.4Ti1.6(PO4)3 represents an even higher degree of Al³. + Doping. Higher concentrations of Al³⁺ + While the introduction of LATP compounds may slightly reduce bulk conductivity due to lattice distortion, it enhances the structural stability of the material and its chemical compatibility with electrolytes (especially fluorinated electrolytes). It forms a more robust barrier on the surface of the ternary material, further suppressing oxidative side reactions and HF corrosion under high voltage. In summary, the selection of these three LATP compounds is based on a comprehensive consideration of the ionic conductivity, electrochemical stability, and physical barrier function of the coating material.

[0065] In some embodiments of this application, the polycrystalline ternary material includes LiNi. 0.8 Co 0.1 Mn 0.1 O 2、 LiNi 0.85 Co 0.075 Mn0.075 O2 or LiNi 0.8 Co 0.15 Mn 0.05 O2.

[0066] With this setting, select LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811), as a representative of polycrystalline ternary materials, is valued for its high nickel content, which enhances its specific capacity. The polyanionic compound coating can cover grain boundaries and cracks on the surface of polycrystalline particles, suppressing side reactions caused by electrolyte penetration along grain boundaries and reducing the concentration of transition metal ions (especially Ni). 4+ The dissolution of LiNi slows down capacity decay and inhibits rapid increase in internal resistance. 0.85 Co 0.075 Mn 0.075 O2 can further increase the nickel content to 85%, while maintaining a high specific capacity, thus optimizing the balance between cost and structural stability by reducing the cobalt content and slightly adjusting the manganese content. LiNi was chosen. 0.8 Co 0.15 Mn 0.05 O2 can enhance the stability of the layered structure and reduce cation mixing while maintaining a high nickel content and increasing the cobalt content to 15%, while reducing the manganese content to 5% helps to reduce lattice distortion.

[0067] In some embodiments of this application, the single-crystal ternary material includes LiNi. 0.92 Co 0.03 Mn 0.05 O2, LiNi 0.9 Co 0.05 Mn 0.05 O2 or LiNi 0.88 Co 0.09 Mn 0.03 O2.

[0068] This configuration is suitable for LiNi. 0.92 Co 0.03 Mn 0.05 For O2 (ultra-high nickel single crystal NCM), its single crystal structure reduces grain boundary problems and has higher bulk structural stability. However, its extremely high nickel content results in a large amount of residual lithium (such as Li2CO3 and LiOH) on the surface, and the surface Ni³ + / 4+ Highly reactive, it readily undergoes vigorous redox reactions with the electrolyte. The polyanionic compound coating primarily serves as physical isolation and chemical passivation, reducing direct contact between residual lithium on the surface and the electrolyte, inhibiting excessive growth of the electrolytic interface (CEI) and oxygen evolution reactions, thereby stabilizing the interface and mitigating the increase in internal resistance. For LiNi...0.9 Co 0.05 Mn 0.05 O2 can optimize surface stability while maintaining a high nickel content by slightly increasing the proportion of cobalt and manganese. The polyanion coating further consolidates this optimization effect, ensuring consistent performance over long-term cycling. For LiNi... 0.88 Co 0.09 Mn 0.03 O2, with its relatively moderate nickel content, and its cobalt content increased to 9%, helps to enhance structural order.

[0069] In some embodiments of this application, the substrate is provided in various ways, including a first substrate made of polycrystalline ternary material and a second substrate made of monocrystalline ternary material, the surfaces of the first substrate and the second substrate are covered with a coating layer; wherein the mass ratio of the first substrate to the second substrate is (7∶3)-(9∶1).

[0070] This configuration, by combining a first matrix composed of polycrystalline ternary materials with a second matrix composed of monocrystalline ternary materials at a specific mass ratio, and ensuring that both surfaces are coated with a polyanionic compound, allows for synergistic optimization of cell degradation consistency at the material system level. Polycrystalline materials, due to their abundant grain boundaries, are prone to microcracks caused by structural stress in the later stages of cycling, leading to exacerbated interfacial side reactions and typically resulting in rapid capacity decay. Monocrystalline materials, on the other hand, have a complete structure and high bulk stability, but their strong surface activity easily leads to increased interfacial impedance. When both coexist in the electrode at an optimized ratio, the polyanionic coating layer compensates for their respective weaknesses: for polycrystalline materials, it suppresses side reactions at grain boundaries and transition metal dissolution; for monocrystalline materials, it reduces surface side reactions and excessive CEI growth. This makes the degradation rates and patterns of different matrix materials more similar, reducing the dependence on cell selection and matching precision, and fundamentally improving the overall lifespan and reliability of the battery system.

[0071] In some embodiments of this application, the median particle size of the polycrystalline ternary material is 9 μm-11 μm.

[0072] This configuration, by precisely controlling the median particle size of the polycrystalline ternary material within this range, optimizes its tap density and electrode processing performance while ensuring sufficient specific surface area for uniform coating coverage. Within this particle size range, the number and distribution of grain boundaries within the particles are relatively controllable, which helps the polyanionic compound coating layer to better fill and cover the grain boundaries, suppressing electrolyte penetration along the grain boundaries and the resulting side reactions. This mitigates structural degradation caused by grain boundary issues and improves cycle stability.

[0073] In some embodiments of this application, the median particle size of the single-crystal ternary material is 2μm-6μm.

[0074] This configuration, controlling the median particle size of the single-crystal ternary material within this range, helps to balance its specific surface area and lithium-ion diffusion path length while maintaining high structural stability. Smaller particle sizes can shorten the diffusion distance of lithium ions in the solid phase, improving rate performance.

[0075] According to a second aspect of this application, a process for preparing an active substance is also provided, comprising: The polyanionic compound is mixed with the ternary material to obtain a mixture. The mixture is heated in an aerobic environment to obtain an intermediate product; The intermediate product was pulverized to obtain the active substance; among which, Ternary materials are heated in an aerobic environment to form a matrix, while polyanionic compounds are heated in an aerobic environment to form a coating layer.

[0076] This setup allows for a controlled chemical reaction on the surface of the ternary material during heat treatment in an aerobic environment, forming a stable matrix structure. Simultaneously, the polyanionic compound pyrolyzes under the same conditions and uniformly coats the matrix surface, forming a dense protective layer. This coating layer can suppress side reactions between the ternary material and the electrolyte, reduce the dissolution of transition metals, and thus improve the cycling stability and thermal stability of the material.

[0077] In some embodiments of this application, the heating temperature of the mixture is 650°C-750°C.

[0078] This configuration allows the ternary material to be fully oxidized within this heating temperature range to form a stable crystal structure, while simultaneously enabling the polyanionic compound to achieve dense encapsulation.

[0079] After pulverizing the intermediate product, the process also includes sieving the pulverized intermediate product to obtain the active substance.

[0080] This setup allows for precise control of the particle size distribution of the active material through a sieving process. Particles within a specific size range are conducive to forming a tightly packed electrode structure, ensuring both high tap density and providing channels for lithium-ion diffusion.

[0081] In some embodiments of this application, the substrate has multiple forms, including a first substrate made of a polycrystalline ternary material and a second substrate made of a single-crystal ternary material, wherein the surfaces of both the first and second substrates are covered with a coating layer; wherein... After mixing polycrystalline ternary materials and monocrystalline ternary materials, a premixed material is obtained; The polyanionic compound is mixed with the premixed material to obtain a mixture.

[0082] This design, by introducing a composite matrix structure of polycrystalline and monocrystalline ternary materials, combines the advantages of high specific capacity of polycrystalline materials and structural stability of monocrystalline materials. Grain boundaries between polycrystalline particles provide more lithium-ion migration channels, while monocrystalline particles suppress grain boundary cracking during cycling. The polyanionic compound coating layer simultaneously covers the active sites on both substrate surfaces, forming a continuous protective network.

[0083] According to a third aspect of this application, a positive electrode sheet is also provided, comprising a current collector and a positive electrode material coating coated on the current collector; the positive electrode material coating comprises the active material as described above or the active material prepared by the above-described active material preparation process, a conductive agent, a binder, and a solvent.

[0084] This configuration improves the uniformity and stability of active material adhesion to the current collector, thereby enhancing the battery's rate performance and cycle life. Using the aforementioned active material or its specific preparation process optimizes the morphology and particle size distribution of the material particles, reduces agglomeration, and enhances interfacial compatibility with conductive agents and binders. This helps form a more continuous and stable conductive network, reduces electrode internal resistance, and improves electron and ion transport efficiency. Simultaneously, a uniform coating distribution reduces localized stress concentration and minimizes active material shedding during charging and discharging, further ensuring the battery's long-term reliability.

[0085] In some embodiments of this application, the current collector includes a carbon-coated current collector, the carbon coating of which is made from raw materials composed of acrylic emulsion, deionized water and carbon black.

[0086] This configuration, employing a carbon-coated current collector, with its surface coating composed of acrylic emulsion, deionized water, and carbon black, improves the interfacial contact and conductivity between the current collector and the cathode material coating. The acrylic emulsion acts as a binder, firmly adhering the carbon black particles to the current collector surface, forming a continuous and porous conductive layer. This conductive layer not only reduces the contact resistance between the current collector and the active material, promoting rapid electron transport, but also helps to evenly distribute the current during charging and discharging, reducing the risk of localized overcharging or over-discharging. Simultaneously, the high specific surface area and excellent conductivity of carbon black further enhance the conductive network of the electrode, enabling efficient utilization of the active material. Furthermore, the porous structure of the carbon coating layer facilitates electrolyte wetting and ion transport, thereby synergistically improving the battery's rate performance and cycle stability.

[0087] In some embodiments of this application, the carbon coating layer comprises a raw material consisting of 20wt%-30wt% acrylic emulsion, 60wt%-75wt% deionized water, and 5wt%-15wt% carbon black.

[0088] With this setup, the content of acrylic emulsion is controlled within this range, which ensures that the carbon black particles are evenly dispersed in the carbon coating layer and firmly adhered to the surface of the current collector, while also reducing the risk of decreased coating flexibility or increased internal resistance due to excessive use. The content of deionized water is controlled within this range, which optimizes the rheology of the slurry and ensures the uniformity of the coating process and the drying efficiency. The content of carbon black is controlled within this range, which enables the formation of a continuous conductive network in the electrode and improves the electron conduction efficiency.

[0089] In some embodiments of this application, the carbon black includes at least one of conductive carbon black, furnace black, and acetylene black.

[0090] This configuration, using at least one of conductive carbon black, furnace black, or acetylene black, is chosen because these carbon black materials all possess high conductivity and a large specific surface area, enabling the formation of a conductive network within the electrode and improving electron transport efficiency. Conductive carbon black exhibits excellent dispersibility and conductivity, facilitating the formation of a uniform conductive layer; furnace black has a more developed structure, enhancing the mechanical strength and conductivity durability of the carbon coating layer; and acetylene black, due to its high purity and low impurity content, helps reduce side reactions and improve the chemical stability of the battery. By rationally selecting the type of carbon black, the conductivity, adhesion, and durability of the carbon coating layer can be optimized according to specific application requirements, thereby further improving the overall performance and lifespan of the battery.

[0091] In some embodiments of this application, the positive electrode material coating comprises a raw material consisting of 55wt%-70wt% of active material, 0.5wt%-5wt% of conductive agent, 1wt%-4wt% of binder and 25wt%-40wt% of solvent.

[0092] With this setup, the active material content is controlled within this range, allowing the electrode to have sufficient energy density and capacity, while also providing adequate space for the conductive agent and binder to construct a stable electrode structure. Within this range, the conductive agent content enables the formation of a continuous and efficient conductive network between the active material particles, reducing electrode internal resistance and improving rate performance. Controlling the binder content within this range ensures a strong bond between the active material and conductive agent particles, as well as between the coating and the current collector. Within this range, the solvent content gives the cathode material slurry suitable viscosity and rheological properties, facilitating uniform coating; its dosage must be precisely controlled to ensure drying efficiency and cathode electrode quality.

[0093] In some embodiments of this application, the conductive agent includes a first solvent, a dispersant, and a conductive substance.

[0094] This design, by structuring the conductive agent as a first solvent, dispersant, and conductive material, optimizes the dispersion and conductivity of the conductive agent within the cathode material coating. The first solvent allows the conductive material and dispersant to mix uniformly and form a stable slurry system; the dispersant, through its surface activity, prevents the conductive material from agglomerating and promotes its uniform distribution between the active material and the binder; the conductive material, as the core component, is responsible for constructing continuous electron conduction pathways within the electrode. This layered design not only improves the efficiency of the conductive agent's use but also enhances its interfacial compatibility with the active material and binder, thereby synergistically reducing electrode internal resistance and improving electron transport rate and battery rate performance.

[0095] In some embodiments of this application, the binder includes a second solvent and a binding substance.

[0096] This configuration optimizes the film-forming performance and adhesion of the binder in the cathode material coating. The second solvent ensures the binder material is fully dissolved or dispersed, forming a uniform slurry system that facilitates the coating process. The binder material, as a key component, firmly binds the active material, conductive agent, and other components together through physical entanglement or chemical cross-linking of its polymer chains, resulting in tight adhesion between the coating and the current collector. This structural design not only improves the uniformity of binder distribution within the electrode but also helps alleviate the stress caused by volume changes in the active material during charging and discharging, reducing the risk of coating cracking or peeling, thereby enhancing the structural stability of the electrode and the cycle life of the battery.

[0097] In some embodiments of this application, the solvent includes N-methylpyrrolidone.

[0098] This setup, using N-methylpyrrolidone (NMP) as the solvent, is primarily based on its excellent physicochemical properties and good compatibility with the various components of the electrode slurry. NMP has a high boiling point, strong polarity, and moderate volatility, which can dissolve or disperse binders (such as polymers like PVDF), resulting in a uniform and stable slurry system and reducing component sedimentation or agglomeration.

[0099] In some embodiments of this application, the conductive agent comprises a raw material consisting of 81wt%-84wt% of a first solvent, 5wt%-9wt% of a dispersant, and 10wt%-14wt% of a conductive substance.

[0100] This configuration allows the components in the conductive agent to work synergistically in a specific ratio: the first solvent at this concentration provides good fluidity and a good dispersion medium, which is beneficial for uniform distribution in subsequent processing; the dispersant at this concentration can prevent the agglomeration of conductive substances and improve the stability of the system; and the content of conductive substances at this concentration can ensure conductivity.

[0101] In some embodiments of this application, the first solvent includes N-methylpyrrolidone.

[0102] With this configuration, N-methylpyrrolidone exhibits good solubility and chemical stability, enabling it to disperse active materials and improve the uniformity and consistency of the electrode slurry, thereby enhancing the rate performance and cycle life of the battery.

[0103] In some embodiments of this application, the dispersant includes polyvinylpyrrolidone.

[0104] This configuration is because polyvinylpyrrolidone, as a highly efficient polymeric dispersant, contains both hydrophilic and hydrophobic groups in its molecular structure. It can adsorb onto the particle surface through steric hindrance, forming a stable protective layer, thereby reducing the van der Waals forces between particles, preventing particle agglomeration and sedimentation, and making the system uniform and stable.

[0105] In some embodiments of this application, the conductive material includes acetylene black.

[0106] This configuration can improve the conductivity of the electrode material and enhance the bonding force between the active material and the current collector, thereby improving the rate performance and cycle stability of the battery.

[0107] In some embodiments of this application, the binder comprises a raw material consisting of 90wt%-95wt% of a second solvent and 5wt%-10wt% of a binder substance.

[0108] With this setting, the content of the second solvent within this concentration range can fully dissolve or disperse the binder material, forming a slurry system with suitable viscosity and rheological properties, which facilitates uniform film formation in the coating process; the content of the binder material within this concentration range can ensure sufficient bonding strength.

[0109] In some embodiments of this application, the second solvent includes N-methylpyrrolidone.

[0110] With this configuration, N-methylpyrrolidone, as the second solvent, possesses high polarity and solubility, enabling it to dissolve or disperse the binder material and form a uniform and stable slurry system. Its moderate boiling point and evaporation rate contribute to the uniform evaporation of the solvent during the coating process.

[0111] In some embodiments of this application, the binder material includes polyvinylidene fluoride.

[0112] This design allows polyvinylidene fluoride (PVDF) to exhibit excellent chemical and thermal stability, enabling it to withstand electrochemical corrosion and temperature variations in the battery operating environment, thus ensuring the integrity of the electrode structure during long-term cycling. The fluorine atoms in its molecular chain endow the material with strong polarity and high bonding strength, effectively fixing active materials and conductive agents and preventing electrode components from detaching during charge and discharge. Simultaneously, PVDF exhibits good compatibility with N-methylpyrrolidone solvents, forming a homogeneous solution system. This facilitates the formation of a dense and continuous bonding network during slurry coating, thereby enhancing the mechanical strength and interfacial stability of the electrode.

[0113] According to the fourth aspect of this application, a process for preparing a positive electrode sheet is also provided, for preparing the above-mentioned positive electrode sheet, comprising: Active material, conductive agent, binder and solvent are mixed to obtain positive electrode material slurry; The cathode material slurry is coated onto the current collector to obtain the intermediate; The intermediate is dried to obtain the positive electrode sheet; wherein... The cathode material slurry forms a cathode material coating after drying.

[0114] This setup, pre-mixing the active material, conductive agent, binder, and solvent into a slurry, allows for uniform dispersion of each component in the solvent, forming a stable suspension system. This reduces the risk of component segregation or agglomeration after coating, which could affect the consistency of the electrode's electrochemical performance. Coating the slurry onto the current collector allows for precise control of the coating's thickness and areal density, ensuring uniformity in battery capacity and rate performance. The subsequent drying process removes the solvent, allowing the binder to solidify and form a porous electrode structure tightly bonded to the current collector, providing stable channels for lithium-ion migration and electron conduction.

[0115] According to a fifth aspect of this application, a battery is also proposed, comprising the aforementioned positive electrode; or, The positive electrode sheet is prepared by the above-described positive electrode sheet preparation process. The battery includes the above-described positive electrode sheet and has all the beneficial effects of the above-described positive electrode sheet, which will not be repeated here.

[0116] The invention will be further described in detail below through several specific experiments as examples.

[0117] Example 1 1. The polyanionic compound is mixed with a ternary material to obtain a mixture; the mixture is heated in an aerobic environment to obtain an intermediate product; the intermediate product is pulverized to obtain the active material. The mixture comprises 99 wt% ternary material and 1 wt% polyanionic compound, the ternary material comprising LiNi in a mass ratio of 3:1. 0.8 Co 0.1 Mn0.1 O2 and LiNi 0.92 Co 0.03 Mn 0.05 O2, polyanionic compounds including Li 1.3 Al 0.3 Ti 1.7 (PO4)3, LiNi 0.8 Co 0.1 Mn 0.1 The median particle size of O2 is 10 μm, and LiNi 0.92 Co 0.03 Mn 0.05 The median particle size of O2 is 3 μm. Mixing was performed using a high-speed mixer at 500 rpm for 5 minutes, followed by mixing at 1000 rpm for 15 minutes. Heating was carried out in a muffle furnace at 650°C with air for 10 hours. Pulverization was performed using an air jet mill, and the pulverized material was sieved through a 200-mesh sieve to obtain the active material.

[0118] 2. Mix 20wt% acrylic emulsion and 70wt% deionized water at 800rpm for 120min, then add 10wt% furnace black and mix at 1500rpm for 120min. After mixing, transfer to a sand mill and mill 5 times at 1500rpm to obtain the carbon coating material. Use a coating machine to coat the carbon coating material onto both sides of the current collector at a speed of 60m / min to obtain the carbon-coated current collector.

[0119] 3. Add 63wt% N-methylpyrrolidone and 10wt% polyvinylidene fluoride in sequence, stir at 1000rpm for 50min, then add 27wt% N-methylpyrrolidone and stir at 1000rpm for 300min to obtain the adhesive.

[0120] 4. Add 51wt% N-methylpyrrolidone and 5wt% polyvinylpyrrolidone in sequence, and stir at 500rpm for 10min; add 14wt% acetylene black, and stir at 500rpm for 10min; add 30wt% N-methylpyrrolidone, and stir at 100rpm for 60min to obtain the conductive agent.

[0121] 5. Add 64wt% active material, 9wt% binder, and 7wt% conductive agent in sequence, and stir at 500rpm for 120min; then add 6wt% binder, 13wt% conductive agent, and 1wt% N-methylpyrrolidone, and stir at 1200rpm for 120min. After cooling, stir at 1000rpm and adjust the viscosity to 3500cp to obtain the positive electrode material slurry.

[0122] 6. Using a coating machine at a speed of 20 m / min, the positive electrode material slurry is coated on both sides of the carbon-coated current collector. The double-sided areal density (the sum of the areal densities of sides A and B of the electrode) is 28.8 mg / cm³. 2 The coated electrode sheets were rolled to 103 μm, slit, and then baked in an oven at 120°C for 12 hours to obtain the sample of Example 1.

[0123] Example 2 Compared to Example 1, in step 1, Example 2 uses LiTi2(PO4)3 instead of Li in Example 1. 1.3 Al 0.3 Ti 1.7 (PO4)3, the remaining steps are the same as in Example 1, to obtain the sample of Example 2.

[0124] Example 3 Compared to Example 1, in step 1, Example 3 uses Li 1.4 Al 0.4 Ti 1.6 (PO4)3 replaces Li in Example 1 1.3 Al 0.3 Ti 1.7 (PO4)3, the remaining steps are the same as in Example 1, and the sample of Example 3 is obtained.

[0125] Example 4 Compared with Example 1, in step 2, Example 4 uses acetylene black instead of furnace black in Example 1, and the remaining steps are the same as in Example 1, to obtain the sample of Example 4.

[0126] Comparative Example 1: Compared with Example 1, only in step 1 no polyanionic compound is added, while all other raw material ratios, process steps and equipment parameters are completely consistent with Example 1.

[0127] Comparative Example 2: Compared with Example 1, only the carbon coating current collector preparation process in step 2 is omitted, and conventional blank aluminum foil used for lithium-ion battery cathodes is directly used as the current collector. All other raw material ratios, process steps, and equipment parameters are completely consistent with Example 1.

[0128] Testing standards: The aforementioned electrode sheets were fabricated into 21700 cylindrical cells, forming a 5S1P module. The cells were charged at a constant current and constant voltage of 1A to 20.75V, with a cutoff voltage of 0.1A. They were then discharged at a constant current of 10A to 14.25V. After 30 cycles, the difference between the maximum and minimum voltage of all cells at the discharge cutoff point was recorded as the voltage differential.

[0129] In Table 1, C1, C2, C3, C4, and C5 represent the serial numbers of the five 18650 cylindrical cells connected in series in the 5S1P module. The values ​​in Table 1 are the voltages (in mV) of different cells at discharge cutoff after 30 cycles, as well as the voltage difference (i.e., the difference between the maximum and minimum voltages) for that cycle. For example, in Example 1, the discharge cutoff voltage of cell C1 is 2741 mV, that of cell C2 is 2842 mV, that of cell C3 is 2850 mV, that of cell C4 is 2858 mV, and that of cell C5 is 2959 mV, with a voltage difference of 218 mV.

[0130] Test results: Table 1 shows the test data of the battery cells assembled from the electrodes prepared in Examples 1-4 and Comparative Examples 1 and 2.

[0131] Test conclusion: From the test results in Table 1, compared with Comparative Examples 1 and 2, the electrodes prepared in Examples 1-4 all showed advantages in terms of module voltage consistency. Among them, the voltage difference of Example 1 was only 218mV, which was far better than 856mV of Comparative Example 1 and 952mV of Comparative Example 2. This result shows that the active material preparation process and positive electrode structure design adopted in this application can improve the voltage balance between cells, thereby improving the overall performance and reliability of the module.

[0132] Specifically, the stable coating layer formed on the surface of the active material by the polyanionic compounds in Examples 1-4 suppresses surface side reactions and structural degradation of the high-nickel ternary material during cycling, reducing the inconsistency in capacity decay between cells due to intrinsic material differences. Simultaneously, the carbon-coated current collector improves the interfacial contact resistance between the electrode and the current collector, promoting uniform current distribution and reducing local polarization. In Example 2, LATP exhibits a 2-3 order of magnitude improvement in ionic conductivity compared to LTP; therefore, LTP is inferior to LATP.

[0133] Comparative Example 1, without the addition of polyanionic compounds, achieved a voltage drop of 856 mV, confirming the crucial role of the surface coating layer on the active material in suppressing interfacial side reactions and delaying capacity decay in high-nickel materials. Cells lacking this protective layer are more prone to surface reconstruction and impedance growth during cycling, leading to increased performance differentiation among cells. Comparative Example 2, using blank aluminum foil as the current collector, achieved a maximum voltage drop of 952 mV, demonstrating that the carbon-coated current collector plays an irreplaceable role in improving module voltage consistency by reducing contact resistance, improving interfacial wettability, and enhancing mechanical bonding.

[0134] In summary, the technical solution of this application improves the structural and interfacial stability of the cathode material by constructing a polyanionic compound coating layer on the surface of the ternary material. This makes the degradation (including capacity decay and internal resistance growth) of the cell with the active material slower and more uniform, thereby improving the degradation consistency of each cell and making the capacity decay and internal resistance change curves of all cells in the module highly synchronized.

[0135] The above provides a detailed description of an active material and its preparation process, a positive electrode sheet and its preparation process, and a battery provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. An active substance, characterized in that, It includes a matrix and a coating layer covering the surface of the matrix, wherein the matrix comprises a ternary material and the coating layer comprises a polyanionic compound.

2. The active substance according to claim 1, characterized in that, The ternary material includes polycrystalline ternary materials and / or monocrystalline ternary materials; and / or, The polyanionic compound includes at least one of lithium aluminum titanium phosphate, lithium titanium phosphate, and lithium titanium silicon phosphate; and / or, The thickness of the coating layer is 60nm-80nm.

3. The active substance according to claim 2, characterized in that, The lithium aluminum titanium phosphate includes Li 1.3 Al 0.3 Ti 1.7 (PO4)3 and Li 1.4 Al 0.4 Ti 1.6 At least one of (PO4)3; and / or, The polycrystalline ternary material includes LiNi. 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.85 Co 0.075 Mn 0.075 O2 or LiNi 0.8 Co 0.15 Mn 0.05 O2; and / or, The single-crystal ternary material includes LiNi. 0.92 Co 0.03 Mn 0.05 O2, LiNi 0.9 Co 0.05 Mn 0.05 O2 or LiNi 0.88 Co 0.09 Mn 0.03 O2.

4. The active substance according to claim 2, characterized in that, The substrate comprises multiple types, including a first substrate composed of the polycrystalline ternary material and a second substrate composed of the monocrystalline ternary material, wherein the surfaces of both the first substrate and the second substrate are covered with the coating layer; wherein... The mass ratio of the first matrix to the second matrix is ​​(7:3)-(9:1).

5. The active substance according to claim 2, characterized in that, The median grain size of the polycrystalline ternary material is 9μm-11μm; and / or, The median particle size of the single-crystal ternary material is 2μm-6μm.

6. A preparation process for an active substance, characterized in that, include: The polyanionic compound is mixed with the ternary material to obtain a mixture. The mixture is heated in an aerobic environment to obtain an intermediate product; The intermediate product is pulverized to obtain the active substance; wherein... The ternary material is heated in an aerobic environment to form a matrix, and the polyanionic compound is heated in an aerobic environment to form a coating layer.

7. The preparation process of the active substance according to claim 6, characterized in that, The heating temperature of the mixture is 650℃-750℃; and / or, After pulverizing the intermediate product, the process further includes sieving the pulverized intermediate product to obtain the active substance.

8. The preparation process of the active substance according to claim 6, characterized in that, The substrate comprises several types, including a first substrate composed of a polycrystalline ternary material and a second substrate composed of a monocrystalline ternary material, wherein the surfaces of both the first substrate and the second substrate are covered with the coating layer; wherein... After mixing the polycrystalline ternary material and the monocrystalline ternary material, a premixed material is obtained; The polyanionic compound is mixed with the premixed material to obtain a mixture.

9. A positive electrode sheet, characterized in that, It includes a current collector and a positive electrode material coating coated on the current collector; the positive electrode material coating comprises an active material as described in any one of claims 1-5 or an active material prepared by a process described in any one of claims 6-8, a conductive agent, a binder, and a solvent.

10. The positive electrode sheet according to claim 9, characterized in that, The current collector includes a carbon-coated current collector, and the carbon coating layer of the carbon-coated current collector is made from raw materials including acrylic emulsion, deionized water and carbon black.

11. The positive electrode sheet according to claim 10, characterized in that, The carbon coating layer comprises a raw material consisting of 20wt%-30wt% of the acrylic emulsion, 60wt%-75wt% of the deionized water, and 5wt%-15wt% of carbon black; and / or, The carbon black includes at least one of conductive carbon black, furnace black, and acetylene black.

12. The positive electrode sheet according to claim 9, characterized in that, The positive electrode material coating is made from raw materials comprising 55wt%-70wt% of the active material, 0.5wt%-5wt% of the conductive agent, 1wt%-4wt% of the binder, and 25wt%-40wt% of the solvent.

13. The positive electrode sheet according to claim 9, characterized in that, The conductive agent includes a first solvent, a dispersant, and a conductive substance; and / or, The adhesive comprises a second solvent and a binder substance; and / or, The solvent includes N-methylpyrrolidone.

14. The positive electrode sheet according to claim 13, characterized in that, The conductive agent comprises a raw material consisting of 81wt%-84wt% of the first solvent, 5wt%-9wt% of the dispersant, and 10wt%-14wt% of the conductive substance; and / or, The first solvent includes N-methylpyrrolidone; and / or, The dispersant includes polyvinylpyrrolidone; and / or, The conductive material includes acetylene black; and / or, The binder comprises a raw material consisting of 90wt%-95wt% of the second solvent and 5wt%-10wt% of the binder substance; and / or, The second solvent includes N-methylpyrrolidone; and / or, The adhesive material includes polyvinylidene fluoride.

15. A process for preparing a positive electrode sheet, characterized in that, For preparing the positive electrode sheet as described in any one of claims 9-14, comprising: Active material, conductive agent, binder and solvent are mixed to obtain positive electrode material slurry; The positive electrode material slurry is coated onto the current collector to obtain an intermediate; The intermediate is dried to obtain the positive electrode sheet; wherein... The cathode material slurry forms a cathode material coating after drying.

16. A battery, characterized in that, Includes the positive electrode sheet as described in any one of claims 9-14; or, The positive electrode sheet is prepared by the positive electrode sheet preparation process described in claim 15.

Images