A positive electrode material for lithium batteries, a preparation method thereof, and a lithium battery.

Abstract

This application provides a positive electrode material for lithium batteries, a preparation method thereof, and a lithium battery. The positive electrode material includes a main electrode material and a whisker material, wherein the whisker material disperses and coats the main electrode material. In this application, the whisker material disperses and coats the main electrode material, allowing the whiskers to maintain a relatively intact structure while forming a long-range structure with high mechanical strength. Because whisker materials possess characteristics such as high strength, high elastic modulus, high hardness, resistance to stress deformation, and good high-temperature stability, the main electrode material coated with whiskers exhibits high structural stability and can maintain high-temperature stability under high-voltage cycling, thus improving the high-temperature cycle life of lithium ions under high voltage.

Description

Technical Field

[0001] This application relates to the field of lithium battery technology, and in particular to a positive electrode material for lithium batteries, a preparation method thereof, and a lithium battery. Background Technology

[0002] The energy density of lithium-ion batteries is closely related to the cathode material. Lithium cobalt oxide is widely used as the cathode material in lithium-ion batteries due to its high specific capacity, discharge plateau, and compaction density.

[0003] The increase in cathode specific capacity and compaction density significantly improves the energy density of lithium-ion batteries. However, the increase in cathode specific capacity and compaction density leads to a decrease in the lattice stability of lithium cobalt oxide materials. In particular, under high-voltage cycling, the strength and hardness of lithium cobalt oxide particles decrease, and undesirable cracks form inside the particles. This results in continuous side reactions between the cathode material and the electrolyte, which in turn significantly reduces the cycle performance of lithium-ion batteries.

[0004] Therefore, existing technologies still need improvement. Summary of the Invention

[0005] The technical problem to be solved by this application is to provide an electrolyte for lithium batteries and a lithium battery, so as to solve the technical problem that lithium cobalt oxide materials have poor stability at high voltage and cannot be applied to high voltage and high energy density polymer batteries.

[0006] To solve the above problems, this application provides the following technical solution:

[0007] This application proposes a positive electrode material for lithium batteries, comprising an electrode substrate and a whisker material, wherein the whisker material disperses and coats the electrode substrate.

[0008] Furthermore, in the positive electrode material, the whisker material forms an oxide solid solution interface structure with the surface of the electrode main material.

[0009] Furthermore, in the cathode material, the main electrode material is selected from at least one of lithium cobalt oxide cathode material, nickel-cobalt-aluminum ternary cathode material, nickel-cobalt-manganese ternary cathode material, lithium iron phosphate cathode material, and lithium manganese oxide cathode material.

[0010] Furthermore, in the cathode material, the whisker material is selected from metal oxide whisker materials or phosphate whisker materials.

[0011] Furthermore, in the cathode material, the metal oxide is selected from one or more of ZnO, Mg(BO3), Al(BO3), CaCO3, SiC, Al2O3, and MgO;

[0012] The phosphate is selected from one or more of AlPO4, FePO4, Li3PO4 and LiMgPO4.

[0013] Furthermore, in the positive electrode material, the whisker material is selected from whisker materials of fast ion conductors.

[0014] Furthermore, in the cathode material, the fast ion conductor is selected from one or more of Li3V2(PO4)3, Li2ZrS3, Li2O-AlO-SiO2 and Li2O-mB2O3.

[0015] Furthermore, in the positive electrode material, the whisker material is dispersed and coated with the electrode main material by a dispersant.

[0016] Furthermore, in the cathode material, the dispersant is composed of a coupling agent and a surfactant, wherein the coupling agent is selected from one or more of chromium complex coupling agents, silane coupling agents, titanate coupling agents, and aluminate coupling agents; and the surfactant is selected from one or more of stearic acid, sodium dodecylbenzene xanthate, quaternary ammonium compounds, lecithin, fatty acid glycerides, and polysorbate.

[0017] Furthermore, in the cathode material, the whisker material has a diameter of 10–500 nm and a length of 0.5–100 μm.

[0018] Furthermore, in the positive electrode material, the mass ratio of the electrode main material to the whisker powder is 1:(0.0001~0.05).

[0019] Furthermore, in the cathode material, the whisker material is perpendicular to the particle surface of the cathode main material.

[0020] This application also provides a method for preparing a positive electrode material for lithium batteries, comprising:

[0021] Provides a first precursor salt solution and a second precursor for the electrode main material;

[0022] Whisker powder is dispersed in a carbonate solution, then added to the first precursor salt solution and aged to obtain a precursor slurry.

[0023] The precursor slurry is filtered, and the filter residue is calcined to obtain the cathode material precursor.

[0024] The cathode material precursor is mixed with the second precursor and then sintered to obtain the cathode material.

[0025] Furthermore, in the method, the step of dispersing the whisker powder in the carbonate solution specifically includes:

[0026] Add whisker powder and dispersant to the carbonate solution and mix well.

[0027] This application also provides another method for preparing a positive electrode material for lithium batteries, comprising:

[0028] Provide electrode main material powder;

[0029] The electrode main material powder and whisker powder are mixed and then ball-milled to obtain a mixed powder.

[0030] The mixed powder is sintered to obtain a positive electrode material.

[0031] Furthermore, in the method, the step of dispersing the whisker powder in the carbonate solution specifically includes:

[0032] Add whisker powder and dispersant to the carbonate solution and mix well.

[0033] This application also provides a lithium battery, which includes a positive electrode made of the positive electrode material as described above.

[0034] Compared with the prior art, this application has the following advantages:

[0035] In this application, the positive electrode material for lithium batteries utilizes whisker material to disperse and coat the electrode main material, allowing the whiskers to maintain a relatively complete structure while forming a long-range structure with high mechanical strength. Since whisker material has the characteristics of high strength, high elastic modulus, high hardness, resistance to stress deformation, and good high-temperature stability, the electrode main material coated with whiskers has high structural stability and can maintain high-temperature stability under high-voltage cycling, thus improving the high-temperature cycle life of lithium ions under high voltage.

[0036] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the structure of the positive electrode material for lithium batteries provided in the embodiments of this application;

[0038] Figure 2 This is a flowchart of a method for preparing a positive electrode material for lithium batteries according to an embodiment of this application;

[0039] Figure 3 This is a flowchart of a method for preparing a positive electrode material for lithium batteries according to another embodiment of this application. Detailed Implementation

[0040] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] This application provides an embodiment of a positive electrode material for lithium batteries, such as... Figure 1 As shown, it includes electrode main material and whisker material, with the whisker material dispersed and coated on the electrode main material.

[0042] The aforementioned positive electrode material for lithium batteries utilizes whisker materials to disperse and coat the main electrode material, allowing the whiskers to maintain a relatively complete structure while forming a long-range structure with high mechanical strength. Due to the characteristics of whisker materials such as high strength, high elastic modulus, high hardness, resistance to stress deformation, and good high-temperature stability, the main electrode material coated with whiskers has high structural stability and can maintain high-temperature stability under high-voltage cycling, thus improving the high-temperature cycle life of lithium ions under high voltage.

[0043] In this embodiment, the whisker material can be selected from metal oxide whisker materials or phosphate whisker materials. The whisker material can also be selected from fast ion conductor whisker materials. Compared to traditional particulate or amorphous coating materials such as metal oxides, phosphates, and fast ion conductors, whisker materials possess higher mechanical properties, including high strength, high elastic modulus, high hardness, and resistance to deformation. They also exhibit excellent high-temperature resistance, high-heat resistance, and corrosion resistance.

[0044] Optionally, in the positive electrode material for lithium batteries, the metal oxide is selected from one or more of ZnO, Mg(BO3), Al(BO3), CaCO3, SiC, Al2O3 and MgO; the phosphate is selected from one or more of AlPO4, FePO4, Li3PO4 and LiMgPO4; and the fast ion conductor is selected from one or more of Li3V2(PO4)3, Li2ZrS3, Li2O-AlO-SiO2 and Li2O-mB2O3.

[0045] In this embodiment, the electrode material is the main material used as the positive electrode of a lithium battery. It can be any lithium battery positive electrode material available in the prior art, specifically selected from at least one of lithium cobalt oxide positive electrode material, nickel cobalt aluminum ternary positive electrode material, nickel cobalt manganese ternary positive electrode material, lithium iron phosphate positive electrode material, and lithium manganese oxide positive electrode material.

[0046] For example, when the main electrode material is lithium cobalt oxide, the resulting positive electrode material for lithium batteries exhibits good interfacial bonding between the whisker-coated lithium cobalt oxide particles and the tightly bonded interface. This bonding significantly suppresses the generation and propagation of cracks in the lithium cobalt oxide particles. Experiments show that whisker-coated lithium cobalt oxide exhibits higher voltage stability. Even under high-voltage cycling at 4.5–4.6V, the lithium cobalt oxide particles still maintain high particle strength, effectively suppressing the formation of undesirable cracks and reducing continuous side reactions between the positive electrode and the electrolyte, thus significantly improving the cycle stability of lithium-ion batteries.

[0047] Unlike traditional coatings that use granular coatings, island coatings, continuous layered coatings, or amorphous coatings, the lithium battery cathode material provided in this application uses whisker material dispersed to form a network coating on the electrode main material, so that the whiskers can maintain a relatively complete structure and form a long-range structure with high mechanical strength.

[0048] Optionally, in one embodiment, the whisker material provided in the embodiments of this application is perpendicular to the particle surface of the main cathode material, so that the interface between the main cathode material surface and the whisker layer is more tightly bonded, which can further improve the mechanical properties of the material.

[0049] Optionally, in order to achieve uniform dispersion of the whisker material on the surface of the electrode substrate particles, in the cathode material provided in this application embodiment, the whisker material is dispersed and coated with the electrode substrate by a dispersant. The use of a dispersant can overcome the difficulty of dispersing whisker materials, achieving uniform coating of the whisker material on the surface of the electrode substrate particles; and uniform dispersion and coating are conducive to forming a three-dimensional coating layer on the surface of the electrode substrate, increasing the interfacial bonding between the whisker material and the electrode substrate, and strengthening the interface between the whisker material and the electrode substrate.

[0050] Specifically, this application incorporates a specific dispersant during the whisker introduction process. The dispersant adheres to the surface of the whisker material, adjusting the surface forces and making the whisker material easier to disperse, thereby improving the whisker dispersion effect and forming a uniform coating layer on the surface of the electrode substrate particles. This dispersant volatilizes and is removed after high-temperature sintering, leaving no residue on the electrode substrate particles. Furthermore, the dispersion effect can be optimized by controlling parameters such as pH, stirring time, and temperature.

[0051] Optionally, in the positive electrode material provided in this application embodiment, the dispersant is composed of a coupling agent and a surfactant. The coupling agent is selected from one or more of chromium complex coupling agents, silane coupling agents, titanate coupling agents, and aluminate coupling agents. The surfactant is selected from one or more of stearic acid, sodium dodecylbenzene xanthate, quaternary ammonium compounds, lecithin, fatty acid glycerides, and polysorbate.

[0052] The principle behind improving dispersion is mainly based on adhering to the surface of solid particles, making the surface of the aggregated solid particles easier to wet, adjusting the surface forces of the solid particles, and thus making them easier to disperse. In the embodiments of this application, controlling the mass ratio of whisker powder to dispersant between (0.0001-0.05):(0.001-0.01) results in better dispersion.

[0053] Specifically, in the aforementioned cathode material, an oxide solid solution interface structure is formed between the whisker material and the electrode substrate. That is, in the cathode material provided in this application, a good interfacial bond is achieved between the whisker material and the electrode substrate particles. This interface structure can be controlled by high-temperature sintering to strengthen the interface between the whisker material and the electrode substrate. This interface structure is a reaction product of the whisker material surface and the electrode substrate surface at high temperatures, and its thickness is very thin, negligible. This interface structure is formed by the formation of an oxide solid solution layer on the surface of the whisker material and the electrode substrate particles during high-temperature sintering. Since the production of the solid solution layer significantly strengthens the interface between the whisker material and the electrode substrate, it can further improve the strength of the electrode substrate particles and suppress crack formation.

[0054] In this embodiment, the mass ratio of electrode substrate to whisker material is 1:(0.0001~0.05). Excessive whisker content and insufficient electrode substrate content will affect capacity utilization, while insufficient whisker content will result in inadequate protection.

[0055] In the embodiments of this application, the thickness of the coating layer formed by the whisker material is determined by the diameter of the whisker material. Optionally, the diameter of the whisker material is 10-500 nm and the length is 0.5-100 μm.

[0056] In this embodiment, the coating layer formed by the whisker material has a minimal impact on the specific surface area of ​​the electrode substrate. For example, when the electrode substrate is lithium cobalt oxide, the particle size D50 is typically 13–17 μm, ensuring particle strength while maintaining low impedance, and the combination of large and small particles ensures necessary compaction. The specific surface area of ​​the lithium cobalt oxide coated with whisker material is typically 0.15–0.35 m². 2 / g, its coating layer mainly functions to inhibit the reaction between the electrolyte and lithium cobalt oxide on the surface of lithium cobalt oxide, thereby improving the stability of lithium cobalt oxide.

[0057] This application also provides a method for preparing a positive electrode material for lithium batteries, such as... Figure 2 As shown, steps S201 to S204 are included:

[0058] Step S201: Provide a first precursor salt solution and a second precursor for the electrode main material;

[0059] Step S202: Disperse the whisker powder in a carbonate solution, then add it to the first precursor salt solution, and age it to obtain a precursor slurry;

[0060] Step S203: Filter the precursor slurry and calcine the filter residue to obtain the cathode material precursor;

[0061] Step S204: Mix the positive electrode material precursor and the second precursor and then sinter them to obtain the positive electrode material.

[0062] In this embodiment, a whisker-coated reinforced cathode material for lithium batteries is prepared using a co-precipitation coating method. The whisker material is dispersed and coated on the surface of the electrode main material, and the whiskers can maintain a relatively complete structure while forming a long-range structure with high mechanical strength. Since the whisker material has the characteristics of high strength, high elastic modulus, high hardness, resistance to stress deformation, and good high-temperature stability, the electrode main material coated with whiskers has high structural stability and can maintain high-temperature stability under high-voltage cycling, thus improving the high-temperature cycle life of lithium ions under high voltage.

[0063] Specifically, in step S201 above, the main electrode material is the main material of the lithium battery cathode, which can be a lithium battery cathode material available in the prior art, specifically selected from at least one of lithium cobalt oxide cathode material, nickel cobalt aluminum ternary cathode material, nickel cobalt manganese ternary cathode material, lithium iron phosphate cathode material, and lithium manganese oxide cathode material.

[0064] In step S201 above, the first precursor and the second precursor of the electrode main material are precursors corresponding to different metal elements contained in the electrode main material, and the first precursor salt solution is the salt solution corresponding to the first precursor. For example, when the electrode main material is lithium cobalt oxide, the first precursor can be Co3O4, the first precursor salt solution is a cobalt salt solution, and the second precursor can be a lithium salt, which can be one or more of lithium carbonate, lithium hydroxide, lithium nitrate, lithium sulfate, or lithium oxalate. Optionally, the cobalt salt solution is prepared by dissolving a cobalt salt in water, and the cobalt salt can be one or more of cobalt sulfate, cobalt nitrate, or cobalt chloride; the concentration of the cobalt salt solution is 0.05–4.0 mol / L.

[0065] In step S202 above, the whisker material can be selected from whisker materials of metal oxides, whisker materials of phosphates, or whisker materials of fast ion conductors. Compared with traditional particulate or amorphous coating materials such as metal oxides, phosphates, and fast ion conductors, whisker materials have higher mechanical properties, including high strength, high elastic modulus, high hardness, and resistance to deformation. They also have excellent high temperature resistance, high heat resistance, and corrosion resistance. Optionally, the metal oxide is selected from one or more of ZnO, Mg(BO3), Al(BO3), CaCO3, SiC, Al2O3, and MgO; the phosphate is selected from one or more of AlPO4, FePO4, Li3PO4, and LiMgPO4; and the fast ion conductor is selected from one or more of Li3V2(PO4)3, Li2ZrS3, Li2O-AlO-SiO2, and Li2O-mB2O3.

[0066] The whisker material has a diameter of 10–500 nm and a length of 0.5–100 μm. The selection of these parameters ensures the large-scale production and acquisition of whiskers, while also guaranteeing their application in the new coating system.

[0067] In step S202 above, whisker powder is first mixed evenly with carbonate solution, and then added to precursor salt solution. The mixture is stirred to obtain a mixed salt solution containing whiskers. This mixed salt solution containing whiskers is then fed into a reactor for reaction and aging to obtain a precursor slurry. During the aging process, the solution pH is controlled at 9–12, the reaction temperature at 20–80°C, and stirring is performed under an inert atmosphere for 2–20 hours to obtain the precursor slurry.

[0068] The carbonate solution is prepared by dissolving carbonate in water. The carbonate can be one or more of sodium carbonate, sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, potassium carbonate, or potassium bicarbonate. The concentration of the carbonate solution is 0.05–4.0 mol / L.

[0069] In step S203 above, the filtered residue is a mixed salt containing whiskers. Calcination of this residue yields the first precursor containing whiskers, which is the aforementioned cathode material precursor. The calcination conditions are atmospheric, dry air, or oxygen atmosphere, with a calcination time of 1–20 h and a calcination temperature of 400–800 °C.

[0070] In step S203 above, the filter residue can be dried before sintering. For example, it can be dried at a temperature of 90-200℃ for 2-10 hours.

[0071] In step S204 above, the positive electrode material precursor and the second precursor are mixed and then sintered to obtain the positive electrode material. The sintering conditions are atmospheric, dry air or oxygen atmosphere, the sintering time is 1-20h, and the sintering temperature is 800-1300℃.

[0072] In step S204 above, when the positive electrode material precursor and the second precursor are mixed, the electrode main material element corresponding to the first precursor and the electrode main material element corresponding to the second precursor should meet a certain molar ratio to ensure that they can react to form the electrode main material.

[0073] For example, when the main electrode material is lithium cobalt oxide, the precursor of the positive electrode material is a Co3O4 precursor containing whiskers. The main electrode material element corresponding to the first precursor is Co, and the main electrode material element corresponding to the second precursor is lithium salt. The main electrode material element corresponding to the second precursor is Li. Then, it is necessary to control the molar ratio of Co content to lithium in the lithium salt to be 1:(1.0-1.3).

[0074] It can be seen that when the main electrode material is lithium cobalt oxide, the introduction process of the whisker-coated lithium cobalt oxide proposed in this application is simple, compatible with the original lithium cobalt oxide material production process, and compatible with traditional coating materials and structures. It has the characteristics of low cost, high efficiency, and suitability for large-scale production.

[0075] Optionally, in one embodiment, during the process of dispersing whisker powder in a carbonate solution, whisker powder and dispersant are added to the carbonate solution, mixed, and then added to a first precursor salt solution for aging to obtain a precursor slurry.

[0076] In this embodiment, the use of a dispersant can overcome the difficulty of dispersing whisker materials and achieve uniform coating of whisker materials on the surface of electrode main material particles. Uniform dispersion and coating are beneficial to forming a three-dimensional coating layer on the surface of electrode main material, increasing the interfacial bonding between whisker materials and electrode main material, and strengthening the interface between whisker materials and electrode main material.

[0077] Specifically, this application incorporates a specific dispersant during the whisker introduction process. The dispersant adheres to the surface of the whisker material, adjusting the surface forces and making the whisker material easier to disperse, thereby improving the whisker dispersion effect and forming a uniform coating layer on the surface of the electrode substrate particles. This dispersant volatilizes and is removed after high-temperature sintering, leaving no residue on the electrode substrate particles. Furthermore, the dispersion effect can be optimized by controlling parameters such as pH, stirring time, and temperature.

[0078] Optionally, in the positive electrode material provided in this application embodiment, the dispersant is composed of a coupling agent and a surfactant. The coupling agent is selected from one or more of chromium complex coupling agents, silane coupling agents, titanate coupling agents, and aluminate coupling agents. The surfactant is selected from one or more of stearic acid, sodium dodecylbenzene xanthate, quaternary ammonium compounds, lecithin, fatty acid glycerides, and polysorbate.

[0079] In summary, the embodiments of this application disperse and coat whisker materials on the surface of electrode precursor particles, and then sinter them at high temperature to form an oxide solid solution interface structure between the whisker materials and the surface of the electrode precursor particles, which can further strengthen the interface between the whisker materials and the electrode precursor.

[0080] This application also provides another method for preparing a positive electrode material for lithium batteries, such as... Figure 3 As shown, steps S301 to S303 are included:

[0081] Step S301: Provide electrode main material powder;

[0082] Step S302: After mixing the electrode main material powder and whisker powder, the mixture is ball-milled to obtain a mixed powder.

[0083] Step S303: Sinter the mixed powder to obtain the positive electrode material.

[0084] In this embodiment, a whisker-coated reinforced cathode material for lithium batteries is prepared using a solid-phase mixing coating method. The whisker material is dispersed and coated on the surface of the electrode main material, and the whiskers can maintain a relatively complete structure while forming a long-range structure with high mechanical strength. Since the whisker material has the characteristics of high strength, high elastic modulus, high hardness, resistance to stress deformation, and good high-temperature stability, the electrode main material coated with whiskers has high structural stability and can maintain high-temperature stability under high-voltage cycling, thus improving the high-temperature cycle life of lithium ions under high voltage.

[0085] Specifically, in step S301 above, the main electrode material is the main material of the lithium battery cathode, which can be a lithium battery cathode material available in the prior art, specifically selected from at least one of lithium cobalt oxide cathode material, nickel cobalt aluminum ternary cathode material, nickel cobalt manganese ternary cathode material, lithium iron phosphate cathode material, and lithium manganese oxide cathode material.

[0086] For example, when the main electrode material is lithium cobalt oxide, the lithium source and cobalt source can be weighed according to the molar ratio of elements shown in the chemical formula of the lithium cobalt oxide material, mixed evenly, and then sintered at 800-1300℃ for 1-20 hours, and then cooled to obtain lithium cobalt oxide powder. The lithium source is one or more of lithium carbonate and lithium hydroxide, and the cobalt source is one or more of cobalt tetroxide and cobalt hydroxide.

[0087] In step S302 above, the whisker material can be selected from whisker materials of metal oxides, whisker materials of phosphates, or whisker materials of fast ion conductors. Compared with traditional particulate or amorphous coating materials such as metal oxides, phosphates, and fast ion conductors, whisker materials have higher mechanical properties, including high strength, high elastic modulus, high hardness, and resistance to deformation. They also have excellent high temperature resistance, high heat resistance, and corrosion resistance. Optionally, the metal oxide is selected from one or more of ZnO, Mg(BO3), Al(BO3), CaCO3, SiC, Al2O3, and MgO; the phosphate is selected from one or more of AlPO4, FePO4, Li3PO4, and LiMgPO4; and the fast ion conductor is selected from one or more of Li3V2(PO4)3, Li2ZrS3, Li2O-AlO-SiO2, and Li2O-mB2O3.

[0088] The whisker material has a diameter of 10–500 nm and a length of 0.5–100 μm. The selection of these parameters ensures the large-scale production and acquisition of whiskers, while also guaranteeing their application in the new coating system.

[0089] In step S302 above, the electrode main material powder and the whisker powder are first mixed evenly in a certain mass ratio, and then ball milled to make the whisker powder evenly dispersed in the electrode main material powder, so as to obtain a mixed powder containing whiskers and electrode main material powder.

[0090] Optionally, the mass ratio of the electrode substrate to the whisker material is 1:(0.0001~0.05). Excessive whisker content and insufficient electrode substrate content will affect capacity utilization, while insufficient whisker content and excessively high electrode substrate content will result in inadequate protection.

[0091] In step S303 above, the mixed powder containing whiskers and electrode substrate powder is sintered to obtain the positive electrode material. The sintering conditions are atmospheric, dry air, or oxygen atmosphere, with a sintering time of 1-20 hours and a sintering temperature of 800-1300℃. High-temperature sintering forms an oxide solid solution interface structure between the whisker material and the electrode substrate particles, strengthening the interface between them. This interface structure is a reaction product of the whisker material surface and the electrode substrate surface at high temperature, and its thickness is very thin, negligible. This interface structure is formed by the formation of an oxide solid solution layer on the surface of the whisker material and the electrode substrate particles during high-temperature sintering. Since the production of the solid solution layer significantly strengthens the interface between the whisker material and the electrode substrate, it can further improve the strength of the electrode substrate particles and suppress crack formation.

[0092] Optionally, in one embodiment, in step S302 above, when mixing the electrode main material powder and whisker powder, an appropriate amount of dispersant is added simultaneously, and then ball milling is performed to obtain a mixed powder.

[0093] In this embodiment, the use of a dispersant can overcome the difficulty of dispersing whisker materials and achieve uniform coating of whisker materials on the surface of electrode main material particles. Uniform dispersion and coating are beneficial to forming a three-dimensional coating layer on the surface of electrode main material, increasing the interfacial bonding between whisker materials and electrode main material, and strengthening the interface between whisker materials and electrode main material.

[0094] Specifically, this application incorporates a specific dispersant during the whisker introduction process. The dispersant adheres to the surface of the whisker material, adjusting the surface forces and making the whisker material easier to disperse, thereby improving the whisker dispersion effect and forming a uniform coating layer on the surface of the electrode substrate particles. This dispersant volatilizes and is removed after high-temperature sintering, leaving no residue on the electrode substrate particles.

[0095] For example, when the main electrode material is lithium cobalt oxide, lithium cobalt oxide powder, whisker powder, and dispersant are mixed in a mass ratio of 1:(0.0001~0.05):(0.001~0.01), then ball-milled to obtain mixed powder. The mixed powder is then sintered at 800~1300℃ for 1~20h to obtain a positive electrode material in which whisker material is uniformly dispersed and coated on the surface of lithium cobalt oxide particles.

[0096] It can be seen that when the main electrode material is lithium cobalt oxide, the introduction process of the whisker-coated lithium cobalt oxide proposed in this application is simple, compatible with the original lithium cobalt oxide material production process, and compatible with traditional coating materials and structures. It has the characteristics of low cost, high efficiency, and suitability for large-scale production.

[0097] Optionally, in the positive electrode material provided in this application embodiment, the dispersant is composed of a coupling agent and a surfactant. The coupling agent is selected from one or more of chromium complex coupling agents, silane coupling agents, titanate coupling agents, and aluminate coupling agents. The surfactant is selected from one or more of stearic acid, sodium dodecylbenzene xanthate, quaternary ammonium compounds, lecithin, fatty acid glycerides, and polysorbate.

[0098] In summary, the embodiments of this application disperse and coat the whisker material on the surface of the electrode main material particles, and then sinter at high temperature to form an oxide solid solution interface structure between the whisker material and the surface of the electrode main material particles, which can further strengthen the interface between the whisker material and the electrode main material.

[0099] This application also provides a lithium battery, including a positive electrode made of the positive electrode material as described above.

[0100] In this embodiment, since the positive electrode material is an electrode material with whisker dispersion coating, it has high structural stability. Under high voltage cycling, the high temperature stability of the electrode material is still good, which can significantly improve the stability of the electrode material particles and thus improve the high temperature cycle life of lithium ions under high voltage.

[0101] The lithium battery of this application is prepared using methods known to those skilled in the art.

[0102] For example, when the cathode material is a whisker-coated lithium cobalt oxide cathode material, the battery preparation method provided in this application embodiment is as follows:

[0103] The prepared whisker-coated lithium cobalt oxide is mixed with conductive carbon black or carbon nanotubes and binder polyvinylidene fluoride (PVDF) at a certain mass ratio and then coated on aluminum foil to prepare a positive electrode sheet. Then, it is sequentially made into a battery cell by a negative electrode and a separator commonly used in the art, using methods known in the art such as winding or stacking. The electrode core is then placed in a battery case, electrolyte is added, and then it is sealed to obtain a lithium battery.

[0104] Under a high voltage cutoff of 3.0V to 4.5V, the high temperature cycling test results at 45℃ show that, compared with uncoated lithium cobalt oxide, the battery with whisker-coated lithium cobalt oxide cathode material has significantly better high temperature cycling performance, higher high temperature cycling capacity retention, and longer cycle life.

[0105] The present application will be described in detail below through embodiments.

[0106] Example 1

[0107] (1) Mix 4.0 mol / L carbonate solution, Al2O3 whisker powder and dispersant evenly, and then add it to cobalt salt solution and stir to obtain a mixed salt solution containing whiskers; wherein, the diameter of Al2O3 whisker powder is 50 nm and the length is 10 μm; the dispersant is a mixture of silane coupling agent and sodium dodecylbenzene xanthate.

[0108] (2) The mixed salt solution containing whiskers is fed into the reactor for reaction and aging. Then, the solution pH is controlled at 10 and the temperature at 25°C. The mixture is stirred in inert argon for 10 hours to obtain the precursor slurry.

[0109] (3) The precursor slurry is filtered, the filtered product is dried at 100°C for 8 hours, and then calcined at 600°C for 10 hours to obtain a Co3O4 precursor containing Al2O3 whiskers.

[0110] (4) According to the molar ratio of Co element content in the Co3O4 precursor containing Al2O3 whiskers to lithium element in lithium salt of 1:1.1, a certain amount of the Co3O4 precursor containing Al2O3 whiskers obtained above is mixed with lithium hydroxide. Then the mixture is sintered in dry air at 1000°C for 10 hours, and then cooled, pulverized and sieved to obtain lithium cobalt oxide cathode material coated with Al2O3 whiskers.

[0111] (5) The lithium cobalt oxide positive electrode material coated with Al2O3 whiskers prepared above is mixed with conductive carbon black or carbon tube and binder polyvinylidene fluoride (PVDF) in a certain mass ratio and coated on aluminum foil to prepare a positive electrode sheet. Then, it is made into a battery cell by sequentially winding with graphite negative electrode and separator according to this winding method. Then, the electrode core is placed into the battery case and sealed to obtain battery S1.

[0112] Example 2

[0113] (1) Mix 4.0 mol / L carbonate solution and Al2O3 whisker powder evenly, then add it to cobalt salt solution and stir to obtain a mixed salt solution containing whiskers; wherein, the diameter of Al2O3 whisker powder is 50 nm and the length is 10 μm;

[0114] (2) The mixed salt solution containing whiskers is fed into the reactor for reaction and aging. Then, the solution pH is controlled at 10 and the temperature at 25°C. The mixture is stirred in inert argon for 10 hours to obtain the precursor slurry.

[0115] (3) The precursor slurry is filtered, the filtered product is dried at 100°C for 8 hours, and then calcined at 600°C for 10 hours to obtain a Co3O4 precursor containing Al2O3 whiskers.

[0116] (4) According to the molar ratio of Co element content in the Co3O4 precursor containing Al2O3 whiskers to lithium element in lithium salt of 1:1.1, a certain amount of the Co3O4 precursor containing Al2O3 whiskers obtained above is mixed with lithium hydroxide. Then the mixture is sintered in dry air at 1000°C for 10 hours, and then cooled, pulverized and sieved to obtain lithium cobalt oxide cathode material coated with Al2O3 whiskers.

[0117] (5) The lithium cobalt oxide positive electrode material coated with Al2O3 whiskers prepared above is mixed with conductive carbon black or carbon tube and binder polyvinylidene fluoride (PVDF) in a certain mass ratio and coated on aluminum foil to prepare a positive electrode sheet. Then, it is made into a battery cell by sequentially winding with graphite negative electrode and separator according to this winding method. Then, the electrode core is placed into the battery case and sealed to obtain battery S2.

[0118] Example 3

[0119] (1) Mix 4.0 mol / L carbonate solution, MgO whisker powder and dispersant evenly, and then add it to cobalt salt solution and stir to obtain a mixed salt solution containing whiskers; wherein, the diameter of MgO whisker powder is 70 nm and the length is 15 μm; the dispersant is a mixture of silane coupling agent and sodium dodecylbenzene xanthate.

[0120] (2) The mixed salt solution containing whiskers is fed into the reactor for reaction and aging. Then, the solution pH is controlled at 10 and the temperature at 25°C. The mixture is stirred in inert argon for 10 hours to obtain the precursor slurry.

[0121] (3) Filter the precursor slurry, dry the filtered product at 100°C for 8 hours, and then calcine it at 600°C for 10 hours to obtain a Co3O4 precursor containing MgO whiskers.

[0122] (4) According to the molar ratio of Co element content in the Co3O4 precursor containing MgO whiskers to lithium element in lithium salt of 1:1.1, a certain amount of the Co3O4 precursor containing MgO whiskers obtained above is mixed with lithium hydroxide. Then the mixture is sintered in dry air at 1000°C for 10 hours, and then cooled, pulverized and sieved to obtain lithium cobalt oxide cathode material coated with MgO whiskers.

[0123] (5) The lithium cobalt oxide positive electrode material coated with MgO whiskers prepared above is mixed with conductive carbon black or carbon tube and binder polyvinylidene fluoride (PVDF) in a certain mass ratio and coated on aluminum foil to prepare a positive electrode sheet. Then, it is made into a battery cell by sequentially winding with graphite negative electrode and separator according to this winding method. Then, the electrode core is placed into the battery case and sealed to obtain battery S3.

[0124] Example 4

[0125] (1) Mix 4.0 mol / L carbonate solution, Al2O3 whisker powder and dispersant evenly, and then add it to cobalt salt solution and stir to obtain a mixed salt solution containing whiskers; wherein, the diameter of Al2O3 whisker powder is 100 nm and the length is 20 μm; the dispersant is a mixture of silane coupling agent and sodium dodecylbenzene xanthate.

[0126] (2) The mixed salt solution containing whiskers is fed into the reactor for reaction and aging. Then, the solution pH is controlled at 11 and the temperature at 25°C. The mixture is stirred in inert argon for 10 hours to obtain the precursor slurry.

[0127] (3) The precursor slurry is filtered, the filtered product is dried at 100°C for 8 hours, and then calcined at 600°C for 10 hours to obtain a Co3O4 precursor containing Al2O3 whiskers.

[0128] (4) According to the molar ratio of Co element content in the Co3O4 precursor containing Al2O3 whiskers to lithium element in lithium salt of 1:1.1, a certain amount of the Co3O4 precursor containing Al2O3 whiskers obtained above is mixed with lithium hydroxide. Then the mixture is sintered in dry air at 1000°C for 10 hours, and then cooled, pulverized and sieved to obtain lithium cobalt oxide cathode material coated with Al2O3 whiskers.

[0129] (5) The lithium cobalt oxide positive electrode material coated with Al2O3 whiskers prepared above is mixed with conductive carbon black or carbon tube and binder polyvinylidene fluoride (PVDF) in a certain mass ratio and coated on aluminum foil to prepare a positive electrode sheet. Then, it is made into a battery cell by sequentially winding with graphite negative electrode and separator according to this winding method. Then, the electrode core is placed into the battery case and sealed to obtain battery S4.

[0130] Example 5

[0131] (1) Mix 4.0 mol / L carbonate solution, AlPO4 whisker powder and dispersant evenly, and then add it to cobalt salt solution and stir to obtain a mixed salt solution containing whiskers; wherein, the diameter of AlPO4 whisker powder is 60 nm and the length is 12 μm; the dispersant is a mixture of silane coupling agent and sodium dodecylbenzene xanthate.

[0132] (2) The mixed salt solution containing whiskers is fed into the reactor for reaction and aging. Then, the solution pH is controlled at 10 and the temperature at 25°C. The mixture is stirred in inert argon for 10 hours to obtain the precursor slurry.

[0133] (3) Filter the precursor slurry, dry the filtered product at 100°C for 8 hours, and then calcine it at 600°C for 10 hours to obtain a Co3O4 precursor containing AlPO4 whiskers.

[0134] (4) According to the molar ratio of Co element content in the Co3O4 precursor containing AlPO4 whiskers to lithium element in lithium salt of 1:1.1, a certain amount of the Co3O4 precursor containing AlPO4 whiskers obtained above is mixed with lithium hydroxide. Then the mixture is sintered in dry air at 1000°C for 10 hours, and then cooled, pulverized and sieved to obtain lithium cobalt oxide cathode material coated with AlPO4 whiskers.

[0135] (5) The lithium cobalt oxide positive electrode material coated with AlPO4 whiskers prepared above is mixed with conductive carbon black or carbon tube and binder polyvinylidene fluoride (PVDF) in a certain mass ratio and coated on aluminum foil to prepare a positive electrode sheet. Then, it is made into a battery cell by sequentially winding with graphite negative electrode and separator according to this winding method. Then, the electrode core is placed into the battery case and sealed to obtain battery S5.

[0136] Example 6

[0137] (1) Mix 4.0 mol / L carbonate solution, Li2ZrS3 whisker powder and dispersant evenly, and then add it to cobalt salt solution and stir to obtain a mixed salt solution containing whiskers; wherein, the diameter of Li2ZrS3 whisker powder is 70 nm and the length is 15 μm; the dispersant is a mixture of silane coupling agent and sodium dodecylbenzene xanthate.

[0138] (2) The mixed salt solution containing whiskers is fed into the reactor for reaction and aging. Then, the solution pH is controlled at 10 and the temperature at 25°C. The mixture is stirred in inert argon for 10 hours to obtain the precursor slurry.

[0139] (3) The precursor slurry was filtered, and the filtered product was dried at 100°C for 8 hours and then calcined at 600°C for 10 hours to obtain a Co3O4 precursor containing Li2ZrS3 whiskers.

[0140] (4) According to the molar ratio of Co element content in Co3O4 precursor containing Li2ZrS3 whiskers to lithium element in lithium salt of 1:1.1, a certain amount of Co3O4 precursor containing Li2ZrS3 whiskers obtained above is mixed with lithium hydroxide. Then the mixture is sintered in dry air at 1000℃ for 10h, and then cooled, pulverized and sieved to obtain lithium cobalt oxide cathode material coated with Li2ZrS3 whiskers.

[0141] (5) The Li2ZrS3 whisker-coated lithium cobalt oxide positive electrode material prepared above is mixed with conductive carbon black or carbon tube and binder polyvinylidene fluoride (PVDF) in a certain mass ratio and coated on aluminum foil to prepare a positive electrode sheet. Then, it is made into a battery cell by sequentially winding with graphite negative electrode and separator according to this winding method. Then, the electrode core is placed into the battery case and sealed to obtain battery S6.

[0142] Example 7

[0143] (1) Mix 4.0 mol / L carbonate solution, Al2O3 whisker powder and dispersant evenly, and then add it to a mixed solution of cobalt salt, manganese salt and nickel salt and stir to obtain a mixed salt solution containing whiskers; wherein, the diameter of Al2O3 whisker powder is 50 nm and the length is 10 μm; the dispersant is a mixture of silane coupling agent and sodium dodecylbenzene xanthate;

[0144] (2) The mixed salt solution containing whiskers is fed into the reactor for reaction and aging. Then, the solution pH is controlled at 10 and the temperature at 25°C. The mixture is stirred in inert argon for 10 hours to obtain the precursor slurry.

[0145] (3) The precursor slurry is filtered, the filtered product is dried at 100°C for 8 hours, and then calcined at 600°C for 10 hours to obtain a nickel-cobalt-manganese ternary cathode material precursor containing Al2O3 whiskers.

[0146] (4) According to the molar ratio of the total amount of nickel, cobalt and manganese metal elements in the nickel-cobalt-manganese ternary cathode material precursor containing Al2O3 whiskers to the lithium element in the lithium salt, a certain amount of the nickel-cobalt-manganese ternary cathode material precursor containing Al2O3 whiskers obtained above is mixed with lithium hydroxide. Then the mixture is sintered in dry air at 950°C for 10 hours, and then cooled, pulverized and sieved to obtain the nickel-cobalt-manganese ternary cathode material coated with Al2O3 whiskers.

[0147] (5) The nickel-cobalt-manganese ternary cathode material coated with Al2O3 whiskers prepared above is mixed with conductive carbon black or carbon tube and binder polyvinylidene fluoride (PVDF) in a certain mass ratio and coated on aluminum foil to prepare a cathode sheet. Then, it is made into a battery cell by sequentially winding with graphite anode and separator according to this winding method. Then, the electrode core is placed into the battery case and sealed to obtain battery S7.

[0148] Example 8

[0149] (1) Weigh lithium hydroxide and cobalt tetroxide according to a certain molar ratio, mix them evenly, then sinter at 1000℃ for 10h, cool, and obtain lithium cobalt oxide powder.

[0150] (2) The lithium cobalt oxide powder, Al2O3 whisker powder, and dispersant obtained above are mixed evenly according to the mass ratio of lithium cobalt oxide powder, whisker powder, and dispersant of 1:0.05:0.001, and ball-milled to obtain a mixed powder containing Al2O3 whiskers and lithium cobalt oxide powder, wherein the diameter of the Al2O3 whisker powder is 50nm and the length is 10um; the dispersant is a mixture of silane coupling agent and sodium dodecylbenzene xanthate.

[0151] (3) The mixed powder is sintered in dry air at 1000°C for 10 hours, then cooled, pulverized and sieved to obtain lithium cobalt oxide cathode material coated with Al2O3 whiskers.

[0152] (4) The lithium cobalt oxide positive electrode material coated with Al2O3 whiskers prepared above is mixed with conductive carbon black or carbon tube and binder polyvinylidene fluoride (PVDF) in a certain mass ratio and coated on aluminum foil to prepare a positive electrode sheet. Then, it is made into a battery cell by sequentially winding with graphite negative electrode and separator according to this winding method. Then, the electrode core is placed into the battery case and sealed to obtain battery S8.

[0153] Example 9

[0154] (1) Weigh lithium hydroxide and cobalt tetroxide according to a certain molar ratio, mix them evenly, then sinter at 1000℃ for 10h, cool, and obtain lithium cobalt oxide powder.

[0155] (2) The lithium cobalt oxide powder, MgO whisker powder, and dispersant obtained above are mixed evenly according to the mass ratio of lithium cobalt oxide powder, whisker powder, and dispersant of 1:0.05:0.001, and ball-milled to obtain a mixed powder containing MgO whiskers and lithium cobalt oxide powder, wherein the diameter of the MgO whisker powder is 70nm and the length is 15um; the dispersant is a mixture of silane coupling agent and sodium dodecylbenzene xanthate.

[0156] (3) The mixed powder is sintered in dry air at 1000°C for 10 hours, then cooled, pulverized and sieved to obtain lithium cobalt oxide cathode material coated with MgO whiskers.

[0157] (4) The lithium cobalt oxide positive electrode material coated with MgO whiskers prepared above is mixed with conductive carbon black or carbon tube and binder polyvinylidene fluoride (PVDF) in a certain mass ratio and coated on aluminum foil to prepare a positive electrode sheet. Then, it is made into a battery cell by sequentially winding with graphite negative electrode and separator according to this winding method. Then, the electrode core is placed into the battery case and sealed to obtain battery S9.

[0158] Example 10

[0159] (1) Weigh lithium hydroxide and cobalt tetroxide according to a certain molar ratio, mix them evenly, then sinter at 1000℃ for 10h, cool, and obtain lithium cobalt oxide powder.

[0160] (2) The lithium cobalt oxide powder, Al2O3 whisker powder, and dispersant obtained above are mixed evenly according to the mass ratio of lithium cobalt oxide powder, whisker powder, and dispersant of 1:0.05:0.001, and ball-milled to obtain a mixed powder containing Al2O3 whiskers and lithium cobalt oxide powder, wherein the diameter of the Al2O3 whisker powder is 100nm and the length is 20um; the dispersant is a mixture of silane coupling agent and sodium dodecylbenzene xanthate.

[0161] (3) The mixed powder is sintered in dry air at 1000°C for 10 hours, then cooled, pulverized and sieved to obtain lithium cobalt oxide cathode material coated with Al2O3 whiskers.

[0162] (4) The lithium cobalt oxide positive electrode material coated with Al2O3 whiskers prepared above is mixed with conductive carbon black or carbon tube and binder polyvinylidene fluoride (PVDF) in a certain mass ratio and coated on aluminum foil to prepare a positive electrode sheet. Then, it is made into a battery cell by sequentially winding with graphite negative electrode and separator according to this winding method. Then, the electrode core is placed into the battery case and sealed to obtain battery S10.

[0163] Comparative Example 1

[0164] (1) Add 4.0 mol / L carbonate solution to cobalt salt solution and stir to obtain mixed salt solution;

[0165] (2) The mixed salt solution is fed into the reaction vessel for reaction and aging. Then, the solution pH is controlled at 10 and the temperature at 25°C. The mixture is stirred in an inert argon atmosphere for 10 hours to obtain the precursor slurry.

[0166] (3) The precursor slurry was filtered, and the filtered product was dried at 100°C for 8 hours and then calcined at 600°C for 10 hours to obtain the Co3O4 precursor.

[0167] (4) According to the molar ratio of Co element content in Co3O4 precursor to lithium element in lithium salt of 1:1.1, a certain amount of the Co3O4 precursor obtained above is mixed with lithium hydroxide, and then the mixture is sintered in dry air at 1000℃ for 10h, and then cooled, pulverized and sieved to obtain lithium cobalt oxide cathode material.

[0168] (5) The prepared lithium cobalt oxide positive electrode material is mixed with conductive carbon black or carbon tube and binder polyvinylidene fluoride (PVDF) in a certain mass ratio and coated on aluminum foil to prepare a positive electrode sheet. Then, it is made into a battery cell by sequentially winding with graphite negative electrode and separator. Then, the electrode core is placed into the battery case and sealed to obtain battery D1.

[0169] Comparative Example 2

[0170] (1) Add 4.0 mol / L carbonate solution to a mixed solution of cobalt salt, manganese salt and nickel salt and stir to obtain a mixed salt solution;

[0171] (2) The mixed salt solution is fed into the reaction vessel for reaction and aging. Then, the solution pH is controlled at 10 and the temperature at 25°C. The mixture is stirred in an inert argon atmosphere for 10 hours to obtain the precursor slurry.

[0172] (3) Filter the precursor slurry, dry the filtered product at 100°C for 8 hours, and then calcine it at 600°C for 10 hours to obtain the nickel-cobalt-manganese ternary cathode material precursor.

[0173] (4) According to the molar ratio of the total amount of nickel, cobalt and manganese metal elements in the nickel-cobalt-manganese ternary cathode material precursor to the lithium element in the lithium salt being 1:1, a certain amount of the nickel-cobalt-manganese ternary cathode material precursor obtained above is mixed with lithium hydroxide, and then the mixture is sintered in dry air at 950°C for 10 hours, and then cooled, pulverized and sieved to obtain the nickel-cobalt-manganese ternary cathode material.

[0174] (5) The nickel-cobalt-manganese ternary positive electrode material prepared above is mixed with conductive carbon black or carbon tube and binder polyvinylidene fluoride (PVDF) in a certain mass ratio and coated on aluminum foil to prepare a positive electrode sheet. Then, it is made into a battery cell by sequentially winding with graphite negative electrode and separator according to this winding method. Then, the electrode core is placed into the battery case and sealed to obtain battery D2.

[0175] Comparative Example 3

[0176] (1) Weigh lithium hydroxide and cobalt tetroxide according to a certain molar ratio, mix them evenly, then sinter at 1000℃ for 10h, cool, and obtain lithium cobalt oxide powder.

[0177] (2) The lithium cobalt oxide positive electrode material coated with Al2O3 whiskers prepared above is mixed with conductive carbon black or carbon tube and binder polyvinylidene fluoride (PVDF) in a certain mass ratio and coated on aluminum foil to prepare a positive electrode sheet. Then, it is made into a battery cell by sequentially winding with graphite negative electrode and separator according to this winding method. Then, the electrode core is placed into the battery case and sealed to obtain battery D3.

[0178] Sample performance testing:

[0179] The above-mentioned test batteries S1~S10 and D1~D3 were subjected to electrochemical cycling characterization. The capacity retention rate was tested after 700 cycles at a high temperature of 45℃ under a high voltage cutoff of 3.0V-4.5V. The test results are shown in Table 1 below.

[0180] Table 1

[0181] Battery number Capacity retention rate (%) S1 81 S2 68 S3 75 S4 84 S5 84 S6 86 S7 61 S8 80 S9 76 S10 83 D1 60 D2 45 D3 58

[0182] According to Table 1, comparing Examples 1-6 with Comparative Example 1, the capacity retention rate of the uncoated lithium cobalt oxide battery is only 60%, while the capacity retention rate of the lithium cobalt oxide battery coated with whisker material is higher than 60%. Comparing Example 7 with Comparative Example 2, the capacity retention rate of the uncoated nickel-cobalt-manganese ternary cathode material battery is only 45%, while the capacity retention rate of the nickel-cobalt-manganese ternary cathode material coated with whisker material is 61%. Comparing Examples 8-10 with Comparative Example 3, the capacity retention rate of the uncoated lithium cobalt oxide battery is only 58%, while the capacity retention rate of the lithium cobalt oxide battery coated with whisker material is higher than 76%. This indicates that the co-precipitation coating method can coat the lithium cobalt oxide or nickel-cobalt-manganese ternary cathode material with whisker material. The lithium cobalt oxide or nickel-cobalt-manganese ternary cathode material coated with whisker material has high structural stability and can maintain high-temperature stability under high-voltage cycling, thus improving the high-temperature cycle life of lithium ions under high voltage.

[0183] According to Table 1, comparing Example 1 and Example 2, it can be seen that the use of dispersant can make Al2O3 whisker material uniformly coated on the surface of lithium cobalt oxide particles, which is conducive to forming a three-dimensional coating layer on the surface of the electrode main material, increasing the interfacial bonding between Al2O3 whisker material and lithium cobalt oxide, strengthening the interface between Al2O3 whisker material and lithium cobalt oxide, and further improving the structural stability of lithium cobalt oxide. This allows lithium cobalt oxide to maintain high temperature stability under high voltage cycling and improve the high temperature cycle life of lithium ions under high voltage.

[0184] According to Table 1, comparing Example 1 and Example 4, it can be seen that increasing the size of Al2O3 whisker material from 50nm in diameter and 10µm in length to 100nm in diameter and 20µm in length can increase the capacity retention rate of the prepared battery from 81% to 84%. This indicates that within a certain range, increasing the size of the whisker material can increase the thickness of the coating layer, thereby enabling lithium cobalt oxide to maintain high-temperature stability under high-voltage cycling and improving the high-temperature cycle life of lithium ions under high voltage.

[0185] According to Table 1, comparing Example 1 with Example 8, comparing Example 3 with Example 9, and comparing Example 4 with Example 10, it can be seen that the solid-phase mixed coating method can also coat lithium cobalt oxide with added whisker material. Lithium cobalt oxide coated with whisker material has high structural stability and can maintain high temperature stability under high voltage cycling, which can improve the high temperature cycle life of lithium ions under high voltage.

[0186] According to Table 1, comparing Examples 1 and 5-6, it can be seen that the capacity of the battery prepared using lithium cobalt oxide coated with phosphate AlPO4 and fast ion conductor Li2ZrS3 whisker material is slightly higher than that of lithium cobalt oxide coated with Al2O3 whisker material. This indicates that lithium cobalt oxide coated with phosphate AlPO4 or fast ion conductor Li2ZrS3 whisker material has higher structural stability, can maintain high-temperature stability under high-voltage cycling, and improves the high-temperature cycle life of lithium ions under high voltage.

[0187] In summary, the provided positive electrode material for lithium batteries in this embodiment includes a main electrode material and a whisker material. The whisker material disperses and coats the main electrode material, allowing the whiskers to maintain a relatively complete structure while forming a long-range structure with high mechanical strength. Furthermore, since whisker materials possess advantages such as high strength, hardness, resistance to stress deformation, and good high-temperature stability, the main electrode material with dispersed whisker coating exhibits high structural stability and good high-temperature stability under high-voltage cycling. This significantly improves the stability of the main electrode material particles, thereby enhancing the high-temperature cycle life of lithium ions under high voltage. Therefore, this solves the technical problem in the prior art where lithium cobalt oxide materials have poor stability under high voltage, preventing their application in high-voltage, high-energy-density polymer batteries.

[0188] Although preferred embodiments of the present application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present application.

[0189] The above provides a detailed description of a positive electrode material for lithium batteries, a preparation method thereof, and a lithium battery. 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 method 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. A positive electrode material for lithium batteries, characterized in that, It includes an electrode base material and a whisker material, wherein the whisker material is dispersed to form a network that coats the electrode base material, and an oxide solid solution interface structure is formed between the whisker material and the surface of the electrode base material; The whisker material is selected from whisker materials of fast ion conductors, and the fast ion conductor is selected from one or more of Li3V2(PO4)3, Li2ZrS3, Li2O-AlO-SiO2 and Li2O-mB2O3; The electrode material is selected from at least one of lithium cobalt oxide cathode material, nickel-cobalt-aluminum ternary cathode material, nickel-cobalt-manganese ternary cathode material, lithium iron phosphate cathode material, and lithium manganese oxide cathode material.

2. The cathode material according to claim 1, characterized in that, The whisker material is selected from phosphate whisker materials, and the phosphate is selected from one or more of AlPO4, FePO4, Li3PO4 and LiMgPO4.

3. The cathode material according to claim 1, characterized in that, The whisker material is selected from one or more of ZnO, Mg(BO3), Al(BO3), CaCO3, SiC, Al2O3 and MgO.

4. The cathode material according to claim 1, characterized in that, The whisker material is dispersed and coated onto the electrode substrate by a dispersant.

5. The positive electrode material according to claim 4, characterized in that, The dispersant comprises a coupling agent and a surfactant. The coupling agent is selected from one or more of chromium complex coupling agents, silane coupling agents, titanate coupling agents, and aluminate coupling agents. The surfactant is selected from one or more of stearic acid, sodium dodecylbenzene xanthate, quaternary ammonium compounds, lecithin, fatty acid glycerides, and polysorbate.

6. The cathode material according to claim 1, characterized in that, The whisker material has a diameter of 10~500nm and a length of 0.5~100um.

7. The cathode material according to claim 1, characterized in that, The mass ratio of the electrode material to the whisker powder is 1:(0.0001~0.05).

8. A method for preparing a positive electrode material for lithium batteries as described in any one of claims 1-7, characterized in that, include: Provides a first precursor salt solution and a second precursor for the electrode main material; Whisker powder is dispersed in a carbonate solution, then added to the first precursor salt solution and aged to obtain a precursor slurry. The precursor slurry is filtered, and the filter residue is calcined to obtain the cathode material precursor. The cathode material precursor is mixed with the second precursor and then sintered to obtain the cathode material.

9. The method according to claim 8, characterized in that, The step of dispersing whisker powder in a carbonate solution specifically includes: Add whisker powder and dispersant to the carbonate solution and mix well.

10. A method for preparing a positive electrode material for lithium batteries as described in any one of claims 1-7, characterized in that, include: Provide electrode main material powder; The electrode main material powder and whisker powder are mixed and then ball-milled to obtain a mixed powder. The mixed powder is sintered to obtain a positive electrode material.

11. A lithium battery, characterized in that, Includes a positive electrode, said positive electrode being made of the positive electrode material as described in any one of claims 1 to 7.

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