A composite cathode material, a battery cathode sheet, a battery and a preparation method thereof

Abstract

The application relates to the technical field of batteries, and provides a composite positive electrode material, a battery positive electrode sheet, a battery and a preparation method thereof. The composite positive electrode material comprises a core and a coating layer. The core comprises a positive electrode active material, and the coating layer comprises an organic salt. The cation of the organic salt comprises at least one of cesium ions and rubidium ions. The composite positive electrode material provided by the application is prepared by adding the organic salt on the surface of the positive electrode active material particles to form the coating layer. The coating layer can effectively inhibit the volume change of the positive electrode in the charging and discharging process, and enhance the structural stability. In addition, the coating layer can also isolate the contact between the positive electrode and the electrolyte, form a stable CEI, inhibit the continuous occurrence of electrolyte side reactions and reduce electrolyte gas production. The organic salt coating positive electrode active material effectively improves the structural stability and interface stability of the positive electrode active material, thereby improving the discharge specific capacity and cycle life of the battery under high voltage.

Description

Technical Field

[0001] This application belongs to the field of battery technology, and in particular relates to a composite cathode material, a battery cathode sheet, a battery, and a method for preparing the same. Background Technology

[0002] Currently, battery cathode materials are often susceptible to electrolyte corrosion, leading to structural degradation and surface side reactions. Therefore, higher voltages place greater demands on the structural and interfacial stability of cathode materials. During deep charge-discharge at higher voltages, a large amount of lithium is extracted from the cathode material, inducing irreversible structural changes and resulting in structural degradation. When a large amount of lithium is extracted, the cathode material is in a high oxidation state, undergoing side reactions with the electrolyte, leading to gas production and a thickened CEI layer, thus reducing electrochemical performance.

[0003] Therefore, effectively improving the electrochemical performance of cathode materials at higher voltages is of great significance for enhancing the commercial value of batteries. Summary of the Invention

[0004] The purpose of this application is to provide a composite cathode material, a battery cathode sheet, a battery, and a method for preparing the same, aiming to solve the problem of how to effectively improve the electrochemical performance of the cathode material in a battery at higher voltages.

[0005] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows:

[0006] In a first aspect, this application provides a composite cathode material, comprising a core and a coating layer covering the core, wherein the core comprises a cathode active material and the coating layer comprises an organic salt; the cation of the organic salt comprises at least one of cesium ions and rubidium ions.

[0007] The coating layer provided in this application includes organic salts for forming a CEI membrane.

[0008] The composite cathode material provided in this patent application involves adding organic salts to the surface of the cathode active material particles to form a coating layer. This coating layer effectively suppresses volume deformation of the cathode during charging and discharging, enhancing structural stability. Furthermore, the coating layer isolates the cathode from the electrolyte, forming a stable electrolyte interphase (CEI), suppressing the continuous occurrence of electrolyte side reactions and reducing electrolyte gas production. The organic salt coating of the cathode active material in this application effectively improves the structural and interfacial stability of the cathode active material, thereby increasing the battery's discharge specific capacity and cycle life at high voltages.

[0009] Secondly, this application provides a method for preparing a composite cathode material, comprising:

[0010] Provide a core material and a coating material; coat the core material with the coating material to form a coating layer, thereby obtaining the above-mentioned composite cathode material.

[0011] The composite cathode material of this application has an organic salt coating layer on its surface, which effectively improves the structural stability of the cathode active material under high voltage. Because the organic salt coating layer can conduct lithium ions while reducing contact with the electrolyte, it effectively improves the high-voltage interface stability of the cathode active material.

[0012] The composite cathode material preparation method proposed in this application has controllable conditions and can accurately regulate the interfacial stability and electrochemical performance of the composite cathode material.

[0013] Thirdly, this application provides a battery positive electrode sheet, including a positive current collector and a positive active layer laminated to at least one surface of the positive current collector; the positive active layer includes the above-mentioned composite positive electrode material or the composite positive electrode material prepared by the above-mentioned preparation method.

[0014] Because the composite cathode material of this application has good structural and interfacial stability, the battery cathode proposed in this application has high cutoff voltage, high capacity, and high cycle stability.

[0015] Fourthly, this application provides a battery including the aforementioned positive electrode plate.

[0016] Because the positive electrode of the battery in this application has the characteristics of high cutoff voltage, high capacity and high cycle stability, the battery in this application has the characteristics of high energy density, long cycle life and good rate performance. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 SEM image of NCM811;

[0019] Figure 2 SEM image of NCM811-Rb-Nafion 1.0% provided in Embodiment 1 of this application;

[0020] Figure 3 Cyclic performance test graphs of the battery provided in Example 9 and the NCM811 battery in Comparative Example 1 under conditions of 2.7V-4.5V and 0.5C.

[0021] Figure 4Rate performance test graphs of the battery provided in Example 9 and the NCM811 battery in Comparative Example 1 under conditions of 2.7V-4.5V and 0.5C.

[0022] Figure 5 Cyclic performance test graphs of the battery provided in Example 18 and the lithium cobalt oxide battery in Comparative Example 2 under conditions of 3.0V-4.6V and 0.5C.

[0023] Figure 6 Cyclic performance test graphs of the battery provided in Example 18 and the lithium cobalt oxide battery in Comparative Example 2 under conditions of 3.0V-4.6V and 0.5C.

[0024] Figure 7 Cyclic performance test graphs of the battery provided in Example 19 and the lithium cobalt oxide battery in Comparative Example 2 under conditions of 3.0V-4.6V and 0.5C.

[0025] Figure 8 The cycle performance test graphs of the battery provided in Example 20 and the lithium cobalt oxide battery in Comparative Example 2 under conditions of 3.0V-4.6V and 0.5C. Detailed Implementation

[0026] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0027] In this application, the term "and / or" describes 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, or B existing alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0028] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0029] It should be understood that in the various embodiments of this application, the order of the above processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0030] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0031] The weights of the relevant components mentioned in the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this application is within the scope disclosed in the embodiments of this application. Specifically, the mass described in the embodiments of this application can be a mass unit known in the chemical industry, such as μg, mg, g, or kg.

[0032] The terms “NMP” are abbreviations for “N-Methylpyrrolidone”, representing N-methylpyrrolidone; “Nafion-H” represents perfluorosulfonic acid resin; “Rb” is abbreviation for “Rubidium”, representing the element rubidium; “Cs” is abbreviation for “Cesium”, representing the element cesium; “EC” is abbreviation for “Ethylene Carbonate”, representing ethylene carbonate; “EMC” is abbreviation for “Ethyl Methyl Carbonate”, representing ethyl methyl carbonate; “DMC” is abbreviation for “Dimethyl Carbonate”, representing dimethyl carbonate; “PVDF” is abbreviation for “Polyvinylidene Fluoride”, representing polyvinylidene fluoride; “PP” is abbreviation for “Polypropylene”, representing polypropylene; and “CEI” is abbreviation for “Chemical-Electrochemical Interface”, representing electrochemical interface membrane.

[0033] The first aspect of this application provides a composite cathode material, including a core and a coating layer covering the core. The core includes a cathode active material, and the coating layer includes an organic salt. The cation of the organic salt includes at least one of cesium ions and rubidium ions.

[0034] The composite cathode material provided in this application embodiment forms a coating layer on the surface of the cathode active material using an organic gold salt. The cations of the organic salt include at least one of cesium and rubidium. The coating layer formed by the organic salt effectively reduces / isolates the contact between the cathode active material and the electrolyte, forming a stable CEI film, inhibiting the continuous occurrence of electrolyte side reactions, reducing or avoiding decomposition gas generation and CEI film growth, and improving the interfacial stability of the cathode active material core. Furthermore, the organic salt coating shell can improve the structural stability of the cathode active material core and alleviate structural degradation caused by internal stress during battery charging and discharging. The organic salt coating layer in this composite cathode material effectively improves the structural and interfacial stability of the cathode active material core, thereby increasing the battery's cutoff voltage and improving its energy density and cycle stability.

[0035] In this embodiment, an organic salt refers to a salt formed by the neutralization reaction of an organic acid and a base (which may be an organic base or an inorganic base). This organic salt contains organic groups and metal cations.

[0036] In this embodiment, the cation of the organic salt includes at least one of cesium ions and rubidium ions. In a specific example, the large ionic radius metal cation in the organic salt coating layer can be Cs. + 、Rb + Cs + and Rb + Typical but not limiting cation combinations include cesium and rubidium ions, both of which are metal cations with large ionic radii. Controlling the selection of large-radius metal cations in the organic salt coating layer allows Rb and Cs ions to act as a support, facilitating lithium-ion transport. Simultaneously, the interaction between the anions in the organic salt and lithium ions on the surface of the positive electrode active material and in the electrolyte also promotes lithium-ion migration. This improves the lithium-ion migration kinetics in the organic salt coating layer, increases the ionic conductivity of the coating layer, enhances the rate performance of the battery, and improves the cycle stability of the battery.

[0037] In this application, when the core contains lithium-ion battery positive electrode active material, the composite positive electrode material provided by this application is used in lithium-ion batteries; when the core contains sodium-ion battery positive electrode material, the composite positive electrode material provided by this application is used in sodium-ion batteries.

[0038] In some embodiments, the anionic group in the organic salt includes a polar functional group, which includes at least one of sulfonate, phosphate and carboxylate.

[0039] The coating layer provided in this application includes an organic salt, which contains polar functional groups and cations with large ionic radii. The polar functional groups include sulfonate (-SO₄²⁻) groups. 3- ), phosphate (-PO3H)- ) and carboxylate (-COO) - At least one of the following, cations with large ionic radii include cesium ions (Cs). + ) or rubidium ions (Rb + ).

[0040] Let's take the positive electrode active material of a lithium-ion battery as an example.

[0041] On the one hand, positive electrode active materials (such as lithium iron phosphate, lithium cobalt oxide, and lithium nickel cobalt manganese oxide) typically contain transition metal ions. Polar functional groups in organic salts, such as sulfonate, phosphate, and carboxylate groups, can interact with the transition metals on the surface of the positive electrode material, thereby increasing the bonding force between the organic salt and the positive electrode active material, and improving the structural and interfacial stability of the positive electrode active material core. On the other hand, the interaction between metal cations with large ionic radii and organic groups (such as polymer chains) provides a fast channel for lithium ion migration, increasing the ionic conductivity of the organic salt coating layer and improving the cycle stability of the positive electrode material.

[0042] On the other hand, the structure of the positive electrode active material undergoes irreversible degradation during deep charge-discharge at high voltages. For example, increasing the operating voltage of lithium cobalt oxide causes more lithium ions to be extracted from the crystal lattice, leading to an irreversible phase transition. Cobalt dissolves, accompanied by oxygen release. The highly oxidizing cobalt decomposes the electrolyte, resulting in gas generation, thicker CEI film, and poorer battery cycle performance. The interaction between sulfonate, phosphate, and carboxylate ions and the surface of the positive electrode active material can effectively stabilize cobalt on the surface of the positive electrode material under high voltages, reducing cobalt dissolution; prevent highly oxidizing cobalt from contacting the electrolyte, inhibit interfacial side reactions, reduce interfacial impedance, decrease polarization, and improve the cycle stability and rate performance of the positive electrode material.

[0043] In addition, the positive electrode active material coated with organic salt has a high degree of negative charge delocalization of sulfonate, phosphate and carboxylate in the organic salt on the surface, and the cations are easy to dissociate. It can provide rapid and selective cation transport through electrostatic interaction, promote the desolvation process of lithium ions, and has high ionic conductivity, which further improves the electrochemical performance of composite positive electrode materials.

[0044] In some embodiments, the organic salt includes at least one of the following: an organic salt containing sulfonate, an organic salt containing phosphate, and an organic salt containing carboxylate; the organic salt containing sulfonate includes sulfonated polymer salts; the organic salt containing phosphate includes phytates and phosphorylated polymer salts; and the organic salt containing carboxylate includes carboxylated polymer salts.

[0045] In the embodiments of this application, polymer salt refers to a salt in which a cation (including rubidium ion and / or cesium ion) is combined with an anionic group (such as at least one of sulfonate, phosphate and carboxylate groups) in the polymer chain.

[0046] This application uses polymer salts as coating material, which is beneficial to improving the electrochemical performance of the composite cathode. Polymers such as sulfonated polymers, phosphorylated polymers, and carboxylated polymers have good film-forming properties, stable structures, good high-temperature performance, and a wide electrochemical stability window. This results in the organic salt coating layer having high thermal and electrochemical stability, further improving the electrochemical performance of the composite cathode.

[0047] Furthermore, the phytate includes at least one of rubidium phytate and / or cesium phytate.

[0048] Furthermore, the cation of the polymer salt is rubidium and / or cesium ions, and the anionic group includes at least one polymer group containing a sulfonate group, wherein the polymer is a salt composed of a cation and a sulfonate group.

[0049] In some embodiments, the sulfonated polymer salt includes at least one selected from perfluorosulfonate resin salt, sulfonated polyvinyl alcohol salt, polystyrene sulfonate, sulfonated polyacrylamide salt, and sulfonated polyimide salt, and the sulfonated polymer salt contains rubidium ions and / or cesium ions; the phosphorylated polymer salt includes at least one selected from polyvinyl alcohol phosphate and polyvinyl phosphate, and the phosphorylated polymer salt contains rubidium ions and / or cesium ions; the carboxylated polymer salt includes at least one selected from dextran salt, alginate, polyacrylate, acrylic maleic anhydride copolymer salt, and carboxymethyl cellulose salt, and the carboxylated polymer salt contains rubidium ions and / or cesium ions.

[0050] Furthermore, the sulfonated polymer salt includes at least one of perfluorosulfonic acid resin rubidium salt and / or perfluorosulfonic acid resin cesium salt.

[0051] Furthermore, the phosphorylated polymer salt includes at least one of polyvinyl alcohol rubidium phosphate and / or polyvinyl alcohol cesium phosphate.

[0052] Furthermore, the carboxylated polymer salt includes at least one of dextran rubidium salt and / or dextran cesium salt.

[0053] In some embodiments, the organic salt is a polymer salt, which includes at least one selected from sulfonated polymer salts, phosphorylated polymer salts, and carboxylated polymer salts; the weight-average molecular weight of the polymer in the polymer salt can be from 1,000 to 1,000,000. In specific examples, the weight-average molecular weight of the polymer can be typical but not limiting molecular weights such as 1,000, 4,000, 7,000, 10,000, 40,000, 80,000, 150,000, 300,000, 450,000, 600,000, 750,000, 900,000, and 1,000,000.

[0054] In some embodiments, the organic salt is a polymer salt, which includes at least one of sulfonated polymer salts, phosphorylated polymer salts, and carboxylated polymer salts; wherein the degree of metallization of the polymer in the polymer salt is 1%-100%.

[0055] In specific examples, the degree of metallization of the polymer can be typical but not limiting metallization levels such as 1%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100%.

[0056] In the embodiments of this application, the degree of metallization of the polymer mainly refers to the degree of rubidium and / or cesium metallization of the polymer.

[0057] Controlling the molecular weight and / or metallization degree of polymers (such as sulfonated polymers, phosphorylated polymers, and carboxylated polymers) within this range is beneficial to improving the crystallinity of polymers, enhancing their film-forming properties and ion conductivity, and improving the mechanical properties, structural stability, and ion conductivity of polymer films, thereby improving the structural stability and interfacial stability of composite cathode materials.

[0058] In some embodiments, the positive electrode active material includes lithium-ion battery positive electrode material or sodium-ion battery positive electrode material.

[0059] By forming a uniform coating layer on the surface of these positive electrode active materials with organic salts, the structural stability and interfacial stability of these positive electrode active materials are effectively improved.

[0060] When the core contains lithium-ion battery positive electrode active material, the composite positive electrode material provided in this application is used in lithium-ion batteries; when the core contains sodium-ion battery positive electrode material, the composite positive electrode material provided in this application is used in sodium-ion batteries.

[0061] In some embodiments, the positive electrode active material contains transition metal ions.

[0062] Polar functional groups in organic salts, such as sulfonate, phosphate, and carboxylate groups, can interact with transition metals on the surface of positive electrode active materials, thereby increasing the bonding force between organic salts and positive electrode active materials and improving the structural and interfacial stability of the positive electrode material matrix.

[0063] In some embodiments, the positive electrode active material of a lithium-ion battery includes at least one of a monolithic positive electrode material, a binary positive electrode material, and a ternary positive electrode material.

[0064] Furthermore, the unary cathode material includes at least one of lithium cobalt oxide (LiCoO2) and lithium manganese oxide.

[0065] Furthermore, binary cathode materials include lithium iron phosphate (LiFePO4).

[0066] Furthermore, ternary cathode materials include lithium nickel cobalt manganese oxide (LiNiO2). x Co y MnzO2) and lithium nickel cobalt aluminum oxide (LiNi x Co y At least one of AlzO2.

[0067] The positive electrode active material for sodium-ion batteries includes at least one of Prussian blue compounds, layered oxides, and polyanionic compounds.

[0068] Furthermore, Prussian blue includes Na. 0.61 Fe[Fe(CN)6] 0.94 .

[0069] Furthermore, the layered oxides include Na 0.44 MnO2.

[0070] Furthermore, the polyanionic type includes at least one of NaFePO4 and Na2FeP2O7.

[0071] In some embodiments, the mass ratio of the coating layer to the positive electrode active material is 1 to 500:20000; and / or, the thickness of the coating layer is 5 nm to 100 nm.

[0072] In this application, the mass ratio of organic salt to positive electrode active material is controlled to be 1–500:20000, optionally 50–200:10000. Specific examples show that the mass ratio of organic salt to positive electrode active material can be typical but not limiting, such as 20:20000, 40:20000, 60:20000, 80:20000, 100:20000, 120:20000, 140:20000, 160:20000, 180:20000, 200:20000, 300:20000, 400:20000, and 500:20000. Maintaining a mass ratio of organic salt to positive electrode active material within this range is beneficial for improving the structural and interfacial stability of the composite positive electrode material, while also increasing the proportion of positive electrode active material in the composite positive electrode material, thereby increasing the energy density of the lithium-ion battery.

[0073] In this application embodiment, the thickness of the coating layer is controlled to be 5nm-100nm. Specifically, the coating layer thickness can be typical but not limiting, such as 5nm, 10nm, 15nm, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm, 50nm, 55nm, 60nm, 65nm, 70nm, 75nm, 80nm, 85nm, 90nm, and 100nm. Controlling the thickness of the organic salt coating layer within this range helps improve the structural and interfacial stability of the composite cathode material while shortening the migration path length of lithium ions in the coating layer, thus improving the transport efficiency of lithium ions by the coating layer.

[0074] The second aspect of this application provides a method for preparing a composite cathode material, including:

[0075] Provide a core material and a coating material; coat the core material with the coating material to form a coating layer, thereby obtaining the above-mentioned composite cathode material.

[0076] The preparation method provided in this application is simple to operate and easy to implement.

[0077] The method for preparing composite cathode materials in this application involves forming an organic salt film and coating it onto the surface of the cathode active material core to create a coating layer. This produces a composite cathode material with the cathode active material as the core and an organic salt coating on its outer surface. The coating layer in the composite cathode material prepared by this method effectively improves the structural stability of the cathode active material. Furthermore, because the coating layer contains organic salt, it can conduct lithium ions while reducing the contact between the cathode active material and the electrolyte, thus improving the interfacial stability of the cathode active material.

[0078] Furthermore, existing coating technologies generally employ methods such as co-precipitation, sol-gel, and thermal sintering to coat the surface of cathode materials with a layer of non-ionic conductive oxide materials, such as alumina, magnesium oxide, titanium dioxide, and silicon dioxide. These coating methods struggle to form a uniform network coating. These non-ionic conductive substances affect the ionic conductivity and energy density of the cathode material. This application effectively mitigates the shortcomings of the aforementioned methods by comprehensively utilizing ionicly conductive, lightweight, and low-cost coating materials, possessing high commercial application value.

[0079] In some embodiments, a core material and a coating layer raw material are provided. In this step, the core material includes a positive electrode active material, constituting the core in the composite positive electrode material of the above application. Therefore, the particle size of the core material in this step is the same as the particle size of the raw material of the core in the above application, and the composition of the core material in this step is the same as the composition of the raw material of the core in the above application. The coating layer raw material is the raw material of the coating layer mentioned above.

[0080] Furthermore, the core material includes at least a positive electrode active material; the coating material includes at least an organic salt.

[0081] In some embodiments, the coating material is a polymer salt, which may also be a polymer monomer containing metal ions such as sulfonate, phosphate and carboxylate. The polymer salt coating layer is formed by polymerizing the polymer monomer on the surface of the cathode core material.

[0082] In the embodiments of this application, the polymerization of polymer monomers can be promoted by adding appropriate coupling agents, initiators and other auxiliary agents.

[0083] In some embodiments, the step of coating the coating material onto the surface of the core material to form a coating layer includes: mixing the coating material with the core material by a mechanical mixing method, so that the coating material coats the surface of the core material to form a coating layer.

[0084] Furthermore, organic salts are coated onto the surface of the positive electrode active material using a mechanical mixing method. In a specific example, the organic salts are coated onto the surface of the positive electrode active material by ball milling.

[0085] In some embodiments, the step of coating the substrate material with a coating material to form a coating layer includes:

[0086] The core material, coating material, and solvent are mixed to obtain a mixture;

[0087] The solvent in the mixture is removed, so that the coating material is coated on the surface of the core material to form a coating layer, thus obtaining a composite cathode material.

[0088] By mixing, the coating material is dissolved in a solvent and the core material is dispersed in the solvent to form a mixture. Then, the solvent in the mixture is removed so that the coating material forms a film and coats the surface of the core material to form a coating layer. This effectively improves the coating rate of the core material and also effectively improves the uniformity of the coating layer thickness.

[0089] In some embodiments, the step includes:

[0090] The positive electrode active material, organic salt, and solvent are mixed to obtain a mixture;

[0091] The solvent in the mixture is removed, so that the organic salt is coated on the surface of the positive electrode active material to obtain a composite positive electrode material.

[0092] In some embodiments, the core material, coating material, and solvent are mixed to obtain a mixture. This mixing process includes, but is not limited to, ball milling, mechanical stirring, drum mixing, and manual grinding. These mixing methods ensure that the core material, coating material, and solvent are uniformly mixed.

[0093] In some embodiments, the core material, the coating material, and the solvent are mixed to obtain a mixture. In this step, the solvent includes at least one of N-methylpyrrolidone, isopropanol, dimethyl sulfoxide, N,N-dimethylformamide, tetrahydrofuran, and deionized water.

[0094] In some embodiments, the core material, coating material, and solvent are mixed to obtain a mixture. In this step, the concentration of organic salts in the mixture is controlled to be between 0.5 mg / mL and 10 mg / mL. In specific examples, the concentration of organic salts can be typical but not limiting concentrations such as 0.5 mg / mL, 1 mg / mL, 2 mg / mL, 3 mg / mL, 4 mg / mL, 5 mg / mL, 6 mg / mL, 7 mg / mL, 8 mg / mL, 9 mg / mL, and 10 mg / mL.

[0095] In some embodiments, the core material, coating material, and solvent are mixed to obtain a mixture. In this step, the concentration of the positive electrode active material in the mixture is controlled to be between 100 mg / mL and 500 mg / mL. In specific examples, the concentration of the positive electrode active material can be typical but not limiting, such as 100 mg / mL, 200 mg / mL, 300 mg / mL, 400 mg / mL, or 500 mg / mL.

[0096] By controlling the concentration of organic salts and / or positive electrode active materials in the mixture within this range, the organic salts are fully dissolved in the solvent, while shortening the time required for subsequent solvent drying.

[0097] In some embodiments, the solvent in the mixture is removed so that the organic salt is coated on the surface of the positive electrode active material to obtain a composite positive electrode material. In this step, the solvent in the mixture is removed by stirring and heating.

[0098] Stirring and heating rapidly remove the solvent from the mixture, promoting the uniform coating of organic salts onto the surface of the positive electrode active material, forming an organic salt coating layer of uniform thickness.

[0099] In some embodiments, the solvent in the mixture is removed so that the organic salt is coated on the surface of the positive electrode active material to obtain a composite positive electrode material. In this step, the solvent in the mixture is removed by spray drying.

[0100] Spray drying can quickly remove solvents, shorten the heating time of the mixture during drying, and further improve the stability of composite cathode materials.

[0101] In some embodiments, the uniformity of the organic salt coating layer on the surface of the positive electrode active material core is controlled. Controlling the uniformity of the organic salt coating layer on the surface of the positive electrode active material ensures that the organic salt coating layer is uniformly coated on the surface of the positive electrode active material core. This helps to further improve the structural and interfacial stability of the positive electrode active material core, while simultaneously reducing the amount of organic salt used, promoting the formation of a uniform CEI film, increasing the proportion of positive electrode active material in the composite positive electrode material, and thus further improving the energy density of the battery.

[0102] In some embodiments, the organic salt in the coating layer raw material is prepared using the following specific method:

[0103] A product containing organic salts is prepared by mixing a basic compound with an organic acid and reacting the mixture.

[0104] In this process, alkaline compounds serve as the metal source.

[0105] Furthermore, the organic acid can be at least one organic acid; as described above, the organic acid contains polar functional groups, including sulfonate anions, phosphate anions and carboxylate anions.

[0106] Furthermore, the organic acid can be a polymer; as described above, polymers include sulfonated polymers, phosphorylated polymers, and carboxylated polymers. Even further, the polymer is at least one of perfluorosulfonic acid resin, phytic acid, and dextran.

[0107] Furthermore, the metallic element in the alkaline compound includes at least one of cesium and rubidium.

[0108] Furthermore, the basic compound includes at least one of carbonates or hydroxides.

[0109] In some embodiments, the organic salt in the coating layer material is a polymer salt, and the specific preparation method is shown below:

[0110] A product containing organic salts is prepared by mixing an alkaline compound with an organic acid and reacting the mixture; the product is then dried to obtain a powder containing organic salts.

[0111] Furthermore, the reaction temperature is 50℃-70℃.

[0112] Furthermore, the alkaline compound is at least one of rubidium hydroxide and cesium hydroxide, and the organic acid is at least one of perfluorosulfonic acid resin, phytic acid, and dextran.

[0113] Furthermore, the alkaline compound is at least one of rubidium carbonate or cesium carbonate, and the organic acid is at least one of perfluorosulfonic acid resin, phytic acid, and dextran.

[0114] In some embodiments, an alkaline compound is stirred with an organic acid at 60°C for 2 hours to obtain a rubidified and / or cesium-modified organic acid solution;

[0115] The above solution was air-dried in a forced-air drying oven for 6 hours, and then dried in a vacuum drying oven at 80°C for more than 12 hours to obtain organometallic rubidium / cesium salt powder.

[0116] The organic acid is at least one of perfluorosulfonic acid resin, phytic acid, and dextran;

[0117] The basic compound is at least one of rubidium hydroxide and cesium hydroxide, or at least one of rubidium carbonate and cesium carbonate.

[0118] A third aspect of this application provides a battery positive electrode sheet, including a positive current collector and a positive active layer laminated to at least one surface of the positive current collector; the positive active layer includes the composite positive electrode material described above or the composite positive electrode material prepared by the above preparation method.

[0119] Because the composite cathode material described above has good structural and interfacial stability, the cathode sheet of the battery in this application has high cutoff voltage, high capacity, and high cycle stability.

[0120] In some embodiments, organic salts are dispersed in the gaps between adjacent composite cathode material particles in the positive electrode active layer.

[0121] Organic salts exhibit desolvation properties. They contain polar functional groups such as sulfonate, phosphate, and carboxyl groups, which strongly attract lithium ions compared to solvent molecules in the electrolyte, thus desolvating them. The high degree of negative charge delocalization in these polar functional groups allows for easy dissociation of cations, providing rapid and selective cation transport through electrostatic interactions, resulting in stronger lithium-ion conductivity than in binders. The large ionic radius metal cations in organic salts interact with polymer chains, providing rapid pathways for lithium-ion migration and increasing the ionic conductivity of the organic salt coating. Organic salts dispersed in composite cathode materials promote lithium-ion desolvation and conduction while reducing solvent molecule penetration.

[0122] In some embodiments, the method for preparing the above-mentioned positive electrode sheet of the battery includes:

[0123] Raw materials including binders, conductive agents, solvents and composite materials are mixed, or raw materials including core materials, coating materials, binders, conductive agents and solvents are mixed to obtain a positive electrode slurry;

[0124] A battery cathode containing composite cathode material is prepared by forming a film of the cathode slurry on a current collector.

[0125] The core material includes the positive electrode active material. The coating material includes organic salts.

[0126] In the battery cathode preparation method of this application, when the cathode slurry includes a composite cathode material, the resulting battery cathode contains the composite cathode material; when the cathode slurry includes a core material and a coating layer material, the coating layer material forms a coating layer on the surface of the core material, thereby forming a composite cathode material. This composite cathode material is the same as the composite cathode material described in the previous application, and will not be elaborated further here.

[0127] The battery cathode preparation method of this application incorporates organic salts. These organic salts have a desolvation effect, promoting the formation of a uniform and stable CEI film on the surface of the cathode active material, thereby effectively improving the stability and rate performance of the battery cathode. The organic salts uniformly coat the surface of the cathode active material, forming a coating layer that reduces electrolyte side reactions and ion dissolution, effectively stabilizing the interface between the cathode active material and the electrolyte, suppressing irreversible phase transitions and oxygen evolution under high voltage, and improving the cycle stability and safety of the battery cathode.

[0128] Furthermore, the process of adding organic salts in the battery cathode preparation method of this application is simple to operate, can be fully adapted to the original battery cathode preparation process and equipment, can achieve precise control of the amount added, and is conducive to large-scale commercial production.

[0129] For the step of "mixing raw materials including binders, conductive agents, solvents and composite materials, or mixing raw materials including core materials, coating layer raw materials, binders, conductive agents and solvents to obtain positive electrode slurry":

[0130] Raw materials, including binders, conductive agents, solvents, and composite materials, are mixed to obtain a positive electrode slurry. This composite positive electrode material is a superposition composite positive electrode material. This step first prepares the positive electrode active material into a composite positive electrode material, and then mixes the composite positive electrode material with raw materials such as binders and conductive agents. This results in a more uniform distribution of organic salts in the composite positive electrode material, more precise control of the coating thickness, and better structural stability of the coating layer.

[0131] Alternatively, raw materials including the core material, coating layer material, binder, conductive agent, and solvent can be mixed to obtain a positive electrode slurry. This step, followed by solvent removal, allows organic salts to coat the surface of the positive electrode active material particles, while also distributing between the particles. Mixing the positive electrode active material, organic salts, binder, conductive agent, and solvent to form the positive electrode slurry simplifies the preparation process of composite positive electrode materials. Furthermore, in addition to coating the surface of the positive electrode active material and forming a composite positive electrode material, organic salts are also distributed between adjacent particles of the composite positive electrode material. These positive electrode active materials and organic salts are those described above.

[0132] In some embodiments, the adhesive includes at least one selected from polyvinylidene fluoride, polyacrylic acid, sodium carboxymethyl cellulose, styrene-butadiene rubber, polytetrafluoroethylene, and polyimide.

[0133] The binder in the positive electrode slurry can provide good adhesion, so that the composite positive electrode material and the conductive material are bonded together and evenly distributed, forming a conductive network and firmly adhering to the current collector, further improving the stability of the positive electrode.

[0134] In some embodiments, the solvent includes at least one of N-methylpyrrolidone, isopropanol, dimethyl sulfoxide, N,N-dimethylformamide, and tetrahydrofuran.

[0135] These solvents have good solubility or dispersibility for the components in the cathode slurry, which helps to form a uniform cathode slurry.

[0136] In some embodiments, the conductive agent includes at least one of Super P conductive carbon, graphite, acetylene black, Ketjen black, carbon nanotubes, graphene, conductive carbon black, and carbon fiber.

[0137] These conductive agents have good dispersibility and conductivity, and can be uniformly dispersed in the positive electrode slurry. At the same time, these conductive agents have good electronic conductivity and chemical stability, which can further improve the stability of the battery positive electrode.

[0138] In some embodiments, the solid content in the positive electrode slurry is 100 mg / mL to 800 mg / mL.

[0139] In specific examples, the solid content in the cathode slurry can be typical but not limiting, such as 100 mg / mL, 200 mg / mL, 300 mg / mL, 400 mg / mL, 500 mg / mL, 600 mg / mL, 700 mg / mL, and 800 mg / mL. Controlling the solid content of the cathode slurry within this range improves its fluidity, thereby enhancing its uniformity and simultaneously increasing the energy density of the battery cathode.

[0140] In some embodiments, the mass ratio of organic salt to positive electrode active material in the positive electrode slurry is controlled to be 1–400:20000, and can be selected as 100–400:20000. In specific examples, the mass ratio of organic salt to positive electrode active material can be 2:20000, 4:20000, 6:20000, 8:20000, 10:20000, 20:20000, 40:20000, 60:20000, 80:20000, 100:20000, 120:20000, 140:20000, or 160:20000. Typical but not limiting mass ratios include 0000, 180:20000, 200:20000, 220:20000, 240:20000, 260:20000, 280:20000, 300:20000, 320:20000, 340:20000, 360:20000, 380:20000, and 400:20000. Controlling the mass ratio of organic salt to positive electrode active material within this range allows the organic salt to improve the stability of the positive electrode interface and cycle stability, while maintaining a high loading of positive electrode active material.

[0141] In some embodiments, the mass ratio of the composite cathode material, binder, and conductive agent in the cathode slurry can be 70–99:20–0.5:10–0.5. Controlling the mass ratio of the composite cathode material, binder, and conductive agent within this range effectively improves the uniformity and stability of the cathode slurry, while increasing the loading of the cathode active material in the resulting cathode sheet, thereby increasing the energy density of the cathode.

[0142] For the step of "forming a film of the positive electrode slurry on the current collector to obtain a battery positive electrode containing a composite positive electrode material":

[0143] In some embodiments, the current collector may be aluminum foil. Further, the thickness of the current collector may be 0.15 mm.

[0144] In some embodiments, the positive electrode slurry is placed on the surface of the current collector by coating, spraying, dipping, or scraping to form a wet film; the wet film is then dried, rolled, and cut to form a positive electrode coating layer, thus obtaining a positive electrode sheet.

[0145] In some embodiments, the thickness of the positive electrode active layer can be set to 0.18 mm to 0.2 mm.

[0146] In some embodiments, the solvent can be removed by first drying with forced air and then drying under vacuum.

[0147] Furthermore, the current collector coated with positive electrode slurry can be dried by forced air drying at 55℃~60℃ for 3h~6h, and then vacuum dried at 110℃ for 8h~12h to fully remove the solvent.

[0148] The fourth aspect of this application provides a battery, including the above-described battery positive electrode sheet, or the battery positive electrode sheet obtained by the above-described preparation method.

[0149] Because the positive electrode of the battery in this application has the characteristics of high cutoff voltage, high capacity and high cycle stability, the battery in this application has high energy density, long cycle life and good rate performance.

[0150] In some embodiments, the battery type includes lithium batteries or sodium batteries.

[0151] The following description is based on specific embodiments.

[0152] Example 1

[0153] This embodiment provides a composite cathode material, which includes a core and a coating layer. The core includes a cathode active material, and the coating layer includes an organic rubidium salt or an organic cesium salt. In this embodiment, the cathode active material is NCM811 (a nickel-cobalt-manganese ternary cathode material; wherein the molar ratio of nickel, cobalt, and manganese is 8:1:1); the organic rubidium salt is a perfluorosulfonic acid resin rubidium salt, and the organic cesium salt is a perfluorosulfonic acid resin cesium salt.

[0154] The preparation method of composite cathode material is as follows:

[0155] Step 1: Dissolve Nafion-H in an isopropanol / water solution (wherein the volume ratio of isopropanol to water is 1:1) to prepare an isopropanol / water solution with a mass percentage of 5% Nafion-H (its molecular weight is approximately 20,000); add rubidium hydroxide or cesium hydroxide to the isopropanol / water solution of Nafion, stir until homogeneous, and obtain a clear solution until the pH is neutral; heat and stir at 80°C and 800 rpm in a fume hood until the solvent is completely evaporated to obtain an organic rubidium salt perfluorosulfonic acid resin rubidium salt, named Rb-Nafion; obtain an organic cesium salt perfluorosulfonic acid resin cesium salt, named Cs-Nafion.

[0156] Step 2: Dissolve the organic salt Rb-Nafion or Cs-Nafion obtained in Step 1 in NMP solution to obtain an organic salt solution with a mass percentage concentration of 1%. Add NCM811 powder to the organic salt solution at a mass ratio of 10000:100 to obtain a mixture. Heat and stir the mixture in a fume hood at 200℃ and 800rpm until the solvent is completely evaporated, allowing Rb-Nafion or Cs-Nafion to uniformly coat the surface of the NCM811 positive electrode active material, thus obtaining the composite positive electrode material.

[0157] Based on the scheme of Example 1, composite cathode materials with Rb-Nafion coating NCM811 and composite cathode materials with Cs-Nafion coating NCM811 can be obtained, and are uniformly named NCM811-Rb-Nafion and NCM811-Cs-Nafion.

[0158] Following the same preparation method, the percentage content of organic salt in the total mass of the positive electrode active material NCM811 and the total mass of organic salt was calculated as follows: the composite positive electrode material with an organic salt content of 1.0% of the total mass was named NCM811-Rb-Nafion1.0%; the composite positive electrode material with an organic salt content of 0.5% of the total mass was named NCM811-Rb-Nafion0.5%.

[0159] Example 2

[0160] This embodiment provides a composite cathode material, which includes a core and a coating layer. The core includes a cathode active material, and the coating layer includes an organic rubidium salt or an organic cesium salt. In this embodiment, the cathode active material is NCM811; the organic rubidium salt is rubidium phytate, and the organic cesium salt is cesium phytate.

[0161] The preparation method of the composite cathode material is the same as that of the composite cathode material preparation method provided in Example 1, except that: in step 1 of the composite cathode material preparation method provided in Example 2, phytic acid aqueous solution is used instead of Nafion isopropanol / aqueous solution.

[0162] Example 3

[0163] This embodiment provides a composite cathode material, which includes a core and a coating layer. The core includes a cathode active material, and the coating layer includes an organic rubidium salt or an organic cesium salt. In this embodiment, the cathode active material is NCM811; the organic rubidium salt is a dextran rubidium salt, and the organic cesium salt is a dextran cesium salt.

[0164] The preparation method of the composite cathode material is the same as that of the composite cathode material provided in Example 1, except that: a dextran aqueous solution is used instead of Nafion's isopropanol / aqueous solution.

[0165] Example 4

[0166] This embodiment provides a positive electrode sheet for a battery, and the positive electrode material of the battery adopts the composite positive electrode material provided in Embodiment 1.

[0167] The specific preparation method is as follows:

[0168] Step 1: Add the composite cathode material, Super P conductive carbon, and PVDF to a mixing tube in a mass ratio of 8:1:1, and then add N-methylpyrrolidone to the mixing tube to achieve a solid concentration of 400 mg / mL. Use a micro-mixer to thoroughly mix the composite cathode material, Super P conductive carbon, PVDF, and N-methylpyrrolidone to obtain the cathode slurry.

[0169] Step 2: Using a coating machine, the positive electrode slurry obtained in Step 1 is coated onto the surface of a 0.15 mm thick aluminum foil to form a slurry film of 0.18 mm thickness. The aluminum foil coated with the slurry film is transferred to a 60°C forced-air drying oven and dried for 3 hours, then transferred to a vacuum oven and vacuum-baked at 110°C for 8 hours to remove residual solvent, allowing the slurry film to form the positive electrode active layer, thus obtaining the electrode sheet. The electrode sheet is rolled using a roller press and cut into circular electrode sheets with a diameter of 12 mm using a cutting machine, thus obtaining the positive electrode sheet of the battery in this embodiment.

[0170] Example 5

[0171] This embodiment provides a positive electrode sheet for a battery, wherein the positive electrode material of the battery is a composite positive electrode material. The composite positive electrode material in this embodiment includes a core and a coating layer. The core includes a positive electrode active material, and the coating layer includes an organic rubidium salt or an organic cesium salt. In this embodiment, the positive electrode active material is NCM811; the organic rubidium salt is Rb-Nafion, and the organic cesium salt is Cs-Nafion.

[0172] The specific preparation method is as follows:

[0173] Step 1: Add NCM811 powder, super P conductive carbon, PVDF, and Rb-Nafion (or replace Rb-Nafion with Cs-Nafion) to a mixing tube at a mass ratio of 8:1:0.92:0.08, where the mass ratio of NCM811 powder to Rb-Nafion (or replace Rb-Nafion with Cs-Nafion) is 100:1. Add N-methylpyrrolidone to the mixing tube to achieve a solid concentration of 400 mg / mL. Mix the lithium cobalt oxide powder, super P conductive carbon, PVDF, Rb-Nafion (or replace Rb-Nafion with Cs-Nafion), and N-methylpyrrolidone using a micro mixer to obtain the positive electrode slurry.

[0174] Step 2: Using a coating machine, the positive electrode slurry obtained in Step 1 is coated onto the surface of a 0.15 mm thick aluminum foil to form a slurry film of 0.2 mm thickness. The aluminum foil coated with the slurry film is transferred to a 60°C forced-air drying oven for 6 hours, and then transferred to a vacuum oven for vacuum baking at 110°C for 12 hours to remove residual solvent, allowing the slurry film to form the positive electrode active layer, thus obtaining the electrode sheet. The electrode sheet is then rolled using a roller press and cut into 12 mm diameter circular electrode sheets using a cutting machine, obtaining the positive electrode sheet of this embodiment. In this positive electrode sheet, Rb-Nafion or Cs-Nafion forms a coating layer on the surface of NCM811 particles, constituting a composite positive electrode material.

[0175] Example 6

[0176] This embodiment provides a positive electrode sheet for a battery, wherein the positive electrode material of the battery is a composite positive electrode material. The composite positive electrode material in this embodiment includes a core and a coating layer. The core includes a positive electrode active material, and the coating layer includes an organic rubidium salt or an organic cesium salt. In this embodiment, the positive electrode active material is NCM811; the organic rubidium salt is Rb-Nafion, and the organic cesium salt is Cs-Nafion.

[0177] The specific preparation method of the positive electrode sheet of the battery is the same as that provided in Example 5, except that: in step 1 of the preparation method of the positive electrode sheet of the battery in Example 6, the ratio of NCM811 powder to Rb-Nafion (or Cs-Nafion is used to replace Rb-Nafion) is 10000:125.

[0178] Example 7

[0179] This embodiment provides a positive electrode sheet for a battery, wherein the positive electrode material of the battery is a composite positive electrode material. The composite positive electrode material in this embodiment includes a core and a coating layer. The core includes a positive electrode active material, and the coating layer includes an organic rubidium salt or an organic cesium salt. In this embodiment, the positive electrode active material is NCM811; the organic rubidium salt is rubidium phytate, and the organic cesium salt is cesium phytate.

[0180] The specific preparation method of the positive electrode sheet of this battery is the same as that provided in Example 5, except that: rubidium phytate salt is used to replace Rb-Nafion in Example 5, or cesium phytate salt is used to replace Cs-Nafion in Example 5.

[0181] Example 8

[0182] This embodiment provides a positive electrode sheet for a battery, wherein the positive electrode material of the battery is a composite positive electrode material. The composite positive electrode material in this embodiment includes a core and a coating layer. The core includes a positive electrode active material, and the coating layer includes an organic rubidium salt or an organic cesium salt. In this embodiment, the positive electrode active material is NCM811; the organic rubidium salt is a dextran rubidium salt, and the organic cesium salt is a dextran cesium salt.

[0183] The specific preparation method of the positive electrode sheet of this battery is the same as that provided in Example 5, except that: rubidium dextran salt is used to replace Rb-Nafion in Example 5, or cesium dextran salt is used to replace Cs-Nafion in Example 5.

[0184] Example 9

[0185] This embodiment provides a battery, specifically a lithium-ion battery. The method for manufacturing this battery is as follows:

[0186] Positive electrode: The positive electrode sheet of the battery provided in Example 4;

[0187] Negative electrode: Lithium foil;

[0188] Separator: 25μm thick PP diaphragm;

[0189] Electrolyte: 1M LiPF6 dissolved in EC / EMC / DMC (volume ratio 1:1:1) electrolyte;

[0190] Lithium-ion battery assembly: The 2016 button cell was assembled in an argon glove box in the following order: positive electrode shell, positive electrode sheet, 45μL electrolyte, PP separator, 5μL electrolyte, lithium sheet, gasket, and negative electrode shell, to obtain the battery of this embodiment.

[0191] Example 10

[0192] This embodiment provides a battery, specifically a lithium-ion battery. The method for manufacturing this battery is as follows:

[0193] Positive electrode: The positive electrode sheet provided in Example 5;

[0194] Negative electrode: Lithium foil;

[0195] Separator: 25μm thick PP diaphragm;

[0196] Electrolyte: 1M LiPF6 dissolved in EC / EMC / DMC (volume ratio 1:1:1) electrolyte;

[0197] Lithium-ion battery assembly: The 2032 coin cell was assembled in an argon glove box in the following order: positive electrode shell, positive electrode sheet, 40μL electrolyte, PP separator, 10μL electrolyte, lithium sheet, gasket, spring sheet, and negative electrode shell, to obtain the battery of this embodiment.

[0198] Example 11

[0199] This embodiment provides a battery, specifically a lithium-ion battery.

[0200] The preparation method of this battery is the same as that of the battery provided in Example 10, except that the positive electrode uses the positive electrode sheet provided in Example 6.

[0201] Example 12

[0202] This embodiment provides a battery, specifically a lithium-ion battery.

[0203] The preparation method of this battery is the same as that of the battery provided in Example 10, except that the positive electrode uses the positive electrode sheet provided in Example 7.

[0204] Example 13

[0205] This embodiment provides a battery, specifically a lithium-ion battery.

[0206] The preparation method of this battery is the same as that of the battery provided in Example 10, except that the positive electrode uses the positive electrode sheet provided in Example 8.

[0207] Example 14

[0208] This embodiment provides a composite cathode material, which includes a core and a coating layer. The core includes a cathode active material, and the coating layer includes an organic rubidium salt or an organic cesium salt. In this embodiment, the cathode active material is lithium cobalt oxide (LCO); the organic rubidium salt is a perfluorosulfonic acid resin rubidium salt, and the organic cesium salt is a perfluorosulfonic acid resin cesium salt.

[0209] The preparation method of this composite cathode is the same as that provided in Example 1, except that lithium cobalt oxide is used instead of NCM811 to obtain Rb-Nafion-coated lithium cobalt oxide (LCO) composite cathode materials and Cs-Nafion-coated lithium cobalt oxide composite cathode materials, which are uniformly named LCO-Rb-Nafion and LCO-Cs-Nafion. Following the same preparation method, the percentage content of organic salt in the total mass of the cathode active material LCO and the total mass of organic salt is calculated as follows: the composite cathode material with 1.0% organic salt content is named LCO-Rb-Nafion 1.0%; the composite cathode material with 0.5% organic salt content is named LCO-Rb-Nafion 0.5%.

[0210] Example 15

[0211] This embodiment provides a positive electrode sheet for a battery, wherein the positive electrode material of the battery is a composite positive electrode material. The composite positive electrode material in this embodiment includes a core and a coating layer. The core includes a positive electrode active material, and the coating layer includes an organic rubidium salt or an organic cesium salt. In this embodiment, the positive electrode active material is LCO; the organic rubidium salt is Rb-Nafion, and the organic cesium salt is Cs-Nafion.

[0212] The specific preparation method of the positive electrode sheet of this battery is the same as that provided in Example 4, except that LCO-Rb-Nafion and LCO-Cs-Nafion are used to replace the composite positive electrode material in Example 4.

[0213] Example 16

[0214] This embodiment provides a positive electrode sheet for a battery, wherein the positive electrode material of the battery is a composite positive electrode material. The composite positive electrode material in this embodiment includes a core and a coating layer. The core includes a positive electrode active material, and the coating layer includes an organic rubidium salt or an organic cesium salt. In this embodiment, the positive electrode active material is LCO; the organic rubidium salt is rubidium phytate, and the organic cesium salt is cesium phytate.

[0215] The specific preparation method of the positive electrode sheet of this battery is the same as that provided in Example 5, except that LCO is used instead of NCM811 in Example 5.

[0216] Example 17

[0217] This embodiment provides a positive electrode sheet for a battery, wherein the positive electrode material of the battery is a composite positive electrode material. The composite positive electrode material in this embodiment includes a core and a coating layer. The core includes a positive electrode active material, and the coating layer includes an organic rubidium salt or an organic cesium salt. In this embodiment, the positive electrode active material is LCO; the organic rubidium salt is a dextran rubidium salt, and the organic cesium salt is a dextran cesium salt.

[0218] The specific preparation method of the positive electrode sheet of this battery is the same as that provided in Example 5, except that: LCO is used to replace NCM811 in Example 5, and dextran cesium salt is used to replace Cs-Nafion in Example 5.

[0219] Example 18

[0220] This embodiment provides a battery, specifically a lithium-ion battery.

[0221] The preparation method of this battery is the same as that of the battery provided in Example 10, except that the positive electrode uses the positive electrode sheet provided in Example 15.

[0222] Example 19

[0223] This embodiment provides a battery, specifically a lithium-ion battery.

[0224] The preparation method of this battery is the same as that of the battery provided in Example 10, except that the positive electrode uses the positive electrode sheet provided in Example 16.

[0225] Example 20

[0226] This embodiment provides a battery, specifically a lithium-ion battery.

[0227] The preparation method of this battery is the same as that of the battery provided in Example 10, except that the positive electrode uses the positive electrode sheet provided in Example 17.

[0228] Comparative Example 1

[0229] This case study presents a battery, specifically an NCM811 battery.

[0230] The preparation method of this battery is the same as that of the battery provided in Example 10, except that the positive electrode active material is NCM811 powder without a coating layer.

[0231] Comparative Example 2

[0232] This case study presents a battery, specifically a lithium cobalt oxide battery.

[0233] The preparation method of this battery is the same as that of the battery provided in Example 10, except that the positive electrode active material is lithium cobalt oxide powder without a coating layer.

[0234] Performance testing:

[0235] 1. Morphological characterization of composite cathode materials.

[0236] In implementation case 1, Figure 1 and Figure 2SEM images of NCM811 powder and NCM811-Rb-Nafion provided in Example 1 are shown.

[0237] 2. Battery performance test.

[0238] The lithium-ion batteries of Example 9 and Comparative Example 1 were tested using a battery testing system. The capacity retention rate of the NCM811 lithium-ion battery of Example 9 after 200 cycles at 2.7V-4.5V and 0.5C was as follows: Figure 3 As shown, the rate performance of the lithium-ion battery in Example 9 is as follows: Figure 4 As shown.

[0239] Using a battery testing system, constant current charge-discharge tests were performed on the LCO lithium-ion batteries of Examples 18 to 20 and the lithium-ion battery of Comparative Example 2 within a voltage range of 3.0V-4.6V. The results are as follows: Figures 5 to 8 As shown.

[0240] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A composite cathode material, characterized in that, It includes a core and a coating layer covering the core, wherein the core includes a positive electrode active material and the coating layer includes an organic salt; The cation of the organic salt includes at least one of cesium ions and rubidium ions.

2. The composite cathode material as described in claim 1, characterized in that, The anionic group of the organic salt contains a polar functional group, which includes at least one of sulfonate, phosphate and carboxylate.

3. The composite cathode material as described in claim 2, characterized in that, The organic salt includes at least one of the following: organic salt containing sulfonate, organic salt containing phosphate, and organic salt containing carboxylate. The sulfonate-containing organic salts include sulfonated polymer salts; The phosphate-containing organic salts include phytates and phosphorylated polymer salts; The carboxylate-containing organic salts include carboxylated polymer salts.

4. The composite cathode material as described in claim 3, characterized in that, The sulfonated polymer salt includes at least one of perfluorosulfonic acid resin salt, sulfonated polyvinyl alcohol salt, polystyrene sulfonate, sulfonated polyacrylamide salt, and sulfonated polyimide salt; The phosphorylated polymer salt includes at least one of polyvinyl alcohol phosphate and polyvinyl phosphate; The carboxylated polymer salt includes at least one of dextran salt, alginate, polyacrylate, acrylic maleic anhydride copolymer salt, and carboxymethyl cellulose salt.

5. The composite cathode material according to any one of claims 1-4, characterized in that, The mass ratio of the coating layer to the positive electrode active material is 1-500:20000; And / or, the thickness of the coating layer is 5nm to 100nm.

6. A method for preparing a composite cathode material, characterized in that, include: Provide core materials and coating material; A coating layer is formed by coating the surface of the core material with the coating material to obtain the composite cathode material according to any one of claims 1-4.

7. The preparation method according to claim 6, characterized in that, The step of coating the coating material onto the surface of the core material to form a coating layer includes: The coating material is mixed with the core material by mechanical mixing, so that the coating material coats the surface of the core material to form a coating layer. Alternatively, the core material, coating material, and solvent are mixed to obtain a mixture; the solvent in the mixture is removed so that the coating material coats the surface of the core material to form a coating layer.

8. A positive electrode sheet for a battery, characterized in that, It includes a positive current collector and a positive active layer laminated to at least one surface of the positive current collector; The positive electrode active layer comprises the composite positive electrode material according to any one of claims 1-5; or, the positive electrode active layer comprises the composite positive electrode material prepared by the preparation method according to claim 6 or 7.

9. The positive electrode of the battery as described in claim 8, characterized in that, In the positive electrode active layer, organic salts are dispersed in the gaps between adjacent composite positive electrode material particles.

10. A battery, characterized in that, Includes the positive electrode sheet of the battery as described in claim 8 or 9.

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