Composite cathode material, preparation method thereof, cathode sheet, battery and electric device

Abstract

The application discloses a composite positive electrode material and a preparation method thereof, a positive electrode sheet, a battery and an electric device. The composite positive electrode material comprises a core and a coating layer on at least part of the surface of the core. The core comprises a positive electrode active material. The coating layer comprises one or more of boric acid, an organic compound with a -B-OH group, an organic compound with a -B-(OH)2 group, and alkali metal salts of each of them. The composite positive electrode material provided by the application can make the battery have good high-temperature cycle performance and high-temperature storage performance.

Description

Technical Field

[0001] This application relates to a composite cathode material and its preparation method, cathode sheet, battery, and electrical device. Background Technology

[0002] In recent years, batteries have been widely used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, and many other fields. With the increasing application and promotion of batteries, higher demands are being placed on their performance under high-temperature environments. As a crucial component of batteries, the long-term stability of the positive electrode active material under high-temperature conditions directly impacts the battery's performance. Summary of the Invention

[0003] This application provides a composite cathode material and its preparation method, cathode sheet, battery and power device, which enables the battery to have good high-temperature cycle performance and high-temperature storage performance.

[0004] The first aspect of this application provides a composite cathode material, the composite cathode material comprising a core and a coating layer located on at least a portion of the surface of the core; the core comprising a cathode active material; the coating layer comprising one or more of boric acid, an organic compound having a -B-OH group, an organic compound having a -B-(OH)2 group, and their respective alkali metal salts.

[0005] The coating material on the surface of the core material of the composite cathode material provided in this application includes boric acid, organic compound molecules, and their alkali metal salts. This coating material can form a uniform coating layer on the surface of the core material, thereby reducing direct contact between the core material and the electrolyte and minimizing side reactions at the cathode-electrolyte interface. Furthermore, the coating material on the surface of the core material of the composite cathode material provided in this application can also function similarly to a solid electrolyte interface protective film, and it has low impedance. Therefore, it can improve the surface stability of the core material without affecting the lithium-ion transport rate, thus contributing to higher capacity and higher first-pass coulombic efficiency in the composite cathode material.

[0006] The B atoms in the coating layer of the composite cathode material provided in this application embodiment can form BO covalent bonds with the low-coordinate oxygen atoms on the surface of the core material, thereby stabilizing the low-coordinate oxygen atoms on the surface of the core material; the -OH and -OMe (Me represents alkali metal) in the coating layer can form bonds with the low-coordinate transition metal atoms on the surface of the core material to achieve the purpose of stabilizing the low-coordinate transition metal atoms.

[0007] Therefore, the coating material can form directional adsorption with the core material, thereby improving the surface stability of the core material and reducing the interaction between the core material and the electrolyte. This can improve the long-term stability of the battery under high temperature conditions, giving the battery good high-temperature cycle performance and high-temperature storage performance.

[0008] In any embodiment, the coating layer is a monolayer.

[0009] In any embodiment, the thickness of the coating layer is 0.2 nm to 3 nm. When the thickness of the coating layer is within the above range, the adsorption between the coating layer material and the core material can be improved, the surface stability of the core material can be enhanced, and the interaction between the core material and the electrolyte can be reduced; it can also reduce the interaction between the core material and the electrolyte without affecting the capacity of the composite cathode material.

[0010] In any embodiment, the adsorption energy between the coating layer and the core is greater than the adsorption energy between the ethylene carbonate compound and the core. This reduces side reactions between the electrolyte and low-coordinate oxygen atoms and transition metal atoms, thereby improving the surface stability of the core material, reducing the interaction between the core material and the electrolyte, and ultimately improving the long-term stability of the battery under high-temperature environments, giving the battery good high-temperature cycling performance and high-temperature storage performance.

[0011] In any embodiment, the positive electrode active material includes one or more of the following: spinel-structured lithium manganese oxide, layered lithium-containing transition metal oxide, and lithium-containing phosphate.

[0012] Optionally, the spinel-structured lithium manganese oxide includes one or more of LiMn2O4 and its doping materials; optionally, the layered lithium-containing transition metal oxide includes one or more of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their respective doping materials; optionally, the lithium-containing phosphate includes one or more of lithium iron phosphate, lithium manganese iron phosphate, and their respective doping materials.

[0013] In any embodiment, the coating layer comprises one or more of boric acid, organic compounds of formulas (1) to (3), and their respective alkali metal salts.

[0014]

[0015] R1, R2, and R3 independently comprise C1-C20 chain alkane groups, C1-C20 oxochain alkane groups, 3-8 membered cyclic alkane groups, 3-8 membered oxochain alkane groups, C2-C20 chain alkenyl groups, C2-C20 oxochain alkenyl groups, 3-8 membered cyclic alkenyl groups, C2-C20 chain alkyne groups, C2-C20 oxochain alkyne groups, 3-8 membered cyclic alkyne groups, 6-18 membered aromatic hydrocarbon groups, 6-18 membered aryloxy groups, 5-12 membered heteroaromatic hydrocarbon groups, and the aforementioned groups being modified by R. a The substituted groups are one or more combinations thereof; optionally, R1, R2, and R3 independently comprise C1-C10 chain alkane groups, C1-C10 oxachain alkane groups, 3-8 membered cyclic alkane groups, 3-8 membered oxachain alkane groups, C2-C10 chain alkenyl groups, C2-C10 oxachain alkenyl groups, 3-8 membered cyclic alkenyl groups, C2-C10 chain alkyne groups, C2-C10 oxachain alkyne groups, 3-8 membered cyclic alkyne groups, 6-10 membered aromatic hydrocarbon groups, 6-10 membered aryloxy groups, 5-10 membered heteroaromatic hydrocarbon groups, and the aforementioned groups being replaced by R a One or more of the substituted groups, in combination.

[0016] R4 includes single bonds, C1-C20 subchain alkane groups, C1-C20 oxoheterochain alkane groups, 3-8 membered subcyclic alkane groups, 3-8 membered oxoheterochain alkane groups, C2-C20 subchain olefin groups, C2-C20 oxoheterochain olefin groups, 3-8 membered subcyclic olefin groups, C2-C20 subchain alkyne groups, C2-C20 oxoheterochain alkyne groups, 3-8 membered subcyclic alkyne groups, 6-18 membered aromatic hydrocarbon groups, 5-12 membered heteroaromatic hydrocarbon groups, and the aforementioned groups being R a The substituted group can be one or more combinations thereof; optionally, R4 includes a single bond, a C1-C10 subchain alkane group, a C1-C10 oxoheterochain alkane group, a 3-8 membered subcyclic alkane group, a 3-8 membered oxoheterochain alkane group, a C2-C10 subchain olefin group, a C2-C10 oxoheterochain olefin group, a 3-8 membered subcyclic olefin group, a C2-C10 subchain alkyne group, a C2-C10 oxoheterochain alkyne group, a 3-8 membered subcyclic alkyne group, a 6-10 membered aromatic hydrocarbon group, a 5-10 membered heteroaromatic hydrocarbon group, and the aforementioned groups being replaced by R. a One or more of the substituted groups, in combination.

[0017] R a Includes one or more combinations of halogen atoms, hydroxyl groups, amino groups, phenyl groups, cyclohexyl groups, C1-C6 chain alkane groups and their halogenated groups, C2-C6 chain olefin groups and their halogenated groups, C1-C6 oxochain alkane groups and their halogenated groups, and C2-C6 oxochain olefin groups and their halogenated groups; optionally, R aIt includes one or more combinations of fluorine atoms, chlorine atoms, bromine atoms, hydroxyl groups, amino groups, phenyl groups, cyclohexyl groups, C1-C4 chain alkane groups and their halogenated groups, C2-C4 chain olefin groups and their halogenated groups, C1-C4 oxochain alkane groups and their halogenated groups, and C2-C4 oxochain olefin groups and their halogenated groups.

[0018] When the organic compounds shown in formulas (1) to (3) are within the above range, they are conducive to the formation of good adsorption between the coating material and the core material, thereby improving the surface stability of the core material, reducing the interaction between the core material and the electrolyte, and thus improving the high-temperature cycle performance and high-temperature storage performance of the battery.

[0019] In any embodiment, R1, R2, and R3 independently comprise C1-C10 chain alkane groups, C1-C10 oxochain alkane groups, 3-8 membered cyclic alkane groups, 3-8 membered oxocyclic alkane groups, and the aforementioned groups are respectively converted by R. a The substituted groups are one or more combinations thereof; optionally, R1, R2, and R3 each independently comprise a C1-C5 chain alkane group, a C1-C5 oxochain alkane group, a 3-5 membered cyclic alkane group, and the aforementioned groups being replaced by R. a The substituted group may be one or more combinations thereof; and / or, R4 may include a single bond, a C1-C10 subchain alkane group, a C1-C10 oxoheterochain alkane group, a 3-8 membered subcyclic alkane group, a 3-8 membered oxoheterocyclic alkane group, and the aforementioned groups may be replaced by R. a The substituted group is one or more combinations thereof; optionally, R4 includes a single bond, a C1-C5 subchain alkane group, and the aforementioned group being replaced by R. a One or more of the substituted groups; and / or, R a It includes one or more combinations of fluorine atoms, chlorine atoms, bromine atoms, hydroxyl groups, and amino groups.

[0020] This can reduce the steric hindrance of organic compound molecules, reduce the battery interface impedance, and further enhance the adsorption between organic compound molecules and the core material, thereby further improving the surface stability of the core material, further reducing the interaction between the core material and the electrolyte, and further improving the high-temperature cycle performance and high-temperature storage performance of the battery.

[0021] In any embodiment, the coating layer comprises one or more of boric acid, the following organic compounds, and their respective alkali metal salts:

[0022]

[0023]

[0024] Optionally, the coating layer comprises one or more of boric acid, organic compounds, and their respective alkali metal salts:

[0025]

[0026]

[0027] When the coating material is within the above range, it can reduce the battery interface impedance, further enhance the adsorption between the coating material and the core material, thereby further improving the surface stability of the core material, further reducing the interaction between the core material and the electrolyte, and further improving the high-temperature cycle performance and high-temperature storage performance of the battery.

[0028] In any embodiment, R1 includes a C2-C10 chain olefin group, a C2-C10 oxochain olefin group, a C2-C10 chain alkyne group, a C2-C10 oxochain alkyne group, and the aforementioned groups being R a The substituted group is one or more combinations thereof; optionally, R1 includes a C2-C5 chain olefin group, a C2-C5 oxochain olefin group, and the aforementioned group being replaced by R. a The substituted groups include one or more combinations thereof; and / or, R2 and R3 independently comprise C1-C10 chain alkane groups, C1-C10 oxachain alkane groups, 3-8 membered cyclic alkane groups, 3-8 membered oxachain alkane groups, C2-C10 chain alkenyl groups, C2-C10 oxachain alkenyl groups, C2-C10 chain alkyne groups, C2-C10 oxachain alkyne groups, and the aforementioned groups being replaced by R a The substituted group is one or more combinations thereof, and at least one of R2 and R3 includes a C2-C10 chain olefin group, a C2-C10 oxochain olefin group, a C2-C10 chain alkyne group, a C2-C10 oxochain alkyne group, and the aforementioned group is replaced by R a The substituted groups are one or more combinations thereof; optionally, R2 and R3 independently comprise C1-C5 chain alkane groups, C1-C5 oxachain alkane groups, C2-C5 chain olefin groups, C2-C5 oxachain olefin groups, C2-C5 chain alkyne groups, C2-C5 oxachain alkyne groups, and the aforementioned groups being replaced by R a The substituted group is one or more of the following combinations, and at least one of R2 and R3 includes a C2-C5 chain olefin group, a C2-C5 oxochain olefin group, and the aforementioned group is replaced by R. a The substituted group is one or more combinations thereof; and / or, R4 includes C2-C10 subchain olefinic group, C2-C10 oxyheterochain olefinic group, C2-C10 subchain alkynyl group, C2-C10 oxyheterochain alkynyl group, and the aforementioned group being replaced by R. aThe substituted groups are one or more combinations thereof; optionally, R4 includes a C2-C5 subchain olefin group, a C2-C5 oxyheterochain olefin group, and the aforementioned groups being replaced by R. a One or more of the substituted groups; and / or, R a It includes one or more combinations of fluorine atoms, chlorine atoms, bromine atoms, hydroxyl groups, and amino groups.

[0029] This can reduce the steric hindrance of organic compound molecules and lower the battery interface impedance. At the same time, the presence of conjugated π bonds in the molecular structure of organic compounds makes it easier for them to form films at the interface, thereby improving interface stability. This, in turn, can further enhance the surface stability of the core material, further reduce the interaction between the core material and the electrolyte, and further improve the high-temperature cycle performance and high-temperature storage performance of the battery.

[0030] In any embodiment, the coating layer comprises one or more of the following organic compounds and their respective alkali metal salts:

[0031]

[0032]

[0033] Optionally, the coating layer comprises one or more of the following organic compounds and their respective alkali metal salts:

[0034]

[0035] When the coating material is within the above range, it can reduce the battery interface impedance, further improve the surface stability of the core material, further reduce the interaction between the core material and the electrolyte, and further improve the high-temperature cycle performance and high-temperature storage performance of the battery.

[0036] In any embodiment, R1 comprises a 3-8 membered cyclic olefinic group, a 3-8 membered cyclic alkyneic group, a 6-10 membered aromatic hydrocarbon group, a 6-10 membered aryloxy group, a 5-10 membered heteroaromatic hydrocarbon group, and the aforementioned groups being coated with R. a The substituted group is one or more combinations thereof; optionally, R1 includes 5-6 membered cyclic alkenyl groups, phenyl groups, phenoxy groups, pyridyl groups, pyrimidinyl groups, benzodioxane groups, benzothiophene groups, triphenylamine groups, and the aforementioned groups being replaced by R. aThe substituted groups include one or more combinations thereof; and / or, R2 and R3 independently comprise, respectively, C1-C10 chain alkane groups, C1-C10 oxachain alkane groups, 3-8 membered cyclic alkane groups, 3-8 membered oxachain alkane groups, C2-C10 chain alkenyl groups, C2-C10 oxachain alkenyl groups, 3-8 membered cyclic alkenyl groups, C2-C10 chain alkyne groups, C2-C10 oxachain alkyne groups, 3-8 membered cyclic alkyne groups, 6-10 membered aromatic hydrocarbon groups, 6-10 membered aryloxy groups, 5-10 membered heteroaromatic hydrocarbon groups, and the aforementioned groups being replaced by R a The substituted groups are one or more combinations thereof, and at least one of R2 and R3 includes a 3-8 membered cyclic olefinic group, a 3-8 membered cyclic alkynyl group, a 6-10 membered aromatic hydrocarbon group, a 6-10 membered aryloxy group, a 5-10 membered heteroaromatic hydrocarbon group, and the aforementioned groups are replaced by R. a The substituted groups are one or more combinations thereof; optionally, R2 and R3 independently comprise C1-C5 chain alkane groups, C1-C5 oxachain alkane groups, C2-C5 chain alkenyl groups, C2-C5 oxachain alkenyl groups, 3-6 membered cyclic alkenyl groups, C2-C5 chain alkyne groups, C2-C5 oxachain alkyne groups, 3-6 membered cyclic alkyne groups, 6-10 membered aromatic hydrocarbon groups, 6-10 membered aryloxy groups, 5-10 membered heteroaromatic hydrocarbon groups, and the aforementioned groups being replaced by R. a A combination of one or more of the substituted groups, and at least one of R2 and R3 includes a phenyl group and the aforementioned group is replaced by R. a The substituted group may be one or more combinations thereof; and / or, R4 may include 3-8 membered subcyclic alkenyl groups, 3-8 membered subcyclic alkyne groups, 6-10 membered aromatic hydrocarbon groups, 5-10 membered heteroaromatic hydrocarbon groups, and the aforementioned groups may be replaced by R. a One or more of the substituted groups; optionally, R4 includes phenyl, biphenyl, and the aforementioned groups replaced by R. a One or more of the substituted groups, in combination.

[0037] Organic compounds contain conjugated π bonds in their molecular structure, which makes it easier for them to form films at the interface, thereby improving the interface stability. This, in turn, can further enhance the surface stability of the core material, further reduce the interaction between the core material and the electrolyte, and further improve the high-temperature cycle performance and high-temperature storage performance of the battery.

[0038] In any embodiment, the coating layer comprises one or more of the following organic compounds and their respective alkali metal salts:

[0039]

[0040]

[0041]

[0042] Optionally, the coating layer comprises one or more of the following organic compounds and their respective alkali metal salts:

[0043]

[0044] When the coating material is within the above range, it can further improve the surface stability of the core material, further reduce the interaction between the core material and the electrolyte, and further improve the high-temperature cycle performance and high-temperature storage performance of the battery.

[0045] In any embodiment, the coating layer includes a first coating layer material and a second coating layer material.

[0046] In any embodiment, the first coating material comprises boric acid, organic compounds of formulas (1) to (3), and one or more of their respective alkali metal salts, and R1, R2, and R3 independently comprise C1-C10 chain alkane groups, C1-C10 oxochain alkane groups, 3-8 membered cyclic alkane groups, 3-8 membered oxocyclic alkane groups, and the aforementioned groups are coated with R a The substituted groups are one or more combinations thereof; optionally, R1, R2, and R3 each independently comprise a C1-C5 chain alkane group, a C1-C5 oxochain alkane group, a 3-5 membered cyclic alkane group, and the aforementioned groups being replaced by R. a The substituted groups include one or more combinations thereof; R4 includes single bonds, C1-C10 subchain alkane groups, C1-C10 oxoheterochain alkane groups, 3-8 membered subcyclic alkane groups, 3-8 membered oxoheterocyclic alkane groups, and the aforementioned groups being replaced by R. a The substituted group is one or more combinations thereof; optionally, R4 includes a single bond, a C1-C5 subchain alkane group, and the aforementioned group being replaced by R. a One or more of the substituted groups; R a It includes one or more combinations of fluorine atoms, chlorine atoms, bromine atoms, hydroxyl groups, and amino groups.

[0047] In any embodiment, the first coating material comprises one or more of boric acid, the following organic compounds, and their respective alkali metal salts:

[0048]

[0049]

[0050] Optionally, the first coating material includes one or more of boric acid, organic compounds, and their respective alkali metal salts:

[0051]

[0052] In any embodiment, the second coating material comprises one or more of the organic compounds of formulas (1) to (3) and their respective alkali metal salts, and R1 comprises C2-C10 chain olefins, C2-C10 oxochain olefins, C2-C10 chain alkynes, C2-C10 oxochain alkynes, 3-8 membered cyclic olefins, 3-8 membered cyclic alkynes, 6-10 membered aromatic hydrocarbons, 6-10 membered aryloxy groups, 5-10 membered heteroaromatic hydrocarbons, and the aforementioned groups are coated with R. a The substituted group is one or more combinations thereof; optionally, R1 includes C2-C5 chain olefin, C2-C5 oxochain olefin, 5-6 membered cyclic olefin, phenyl, phenoxy, pyridyl, pyrimidinyl, benzodioxane, benzothiophene, triphenylamine, and the aforementioned groups being replaced by R. a The substituted groups include one or more combinations thereof; R2 and R3 independently comprise C1-C10 chain alkane groups, C1-C10 oxachain alkane groups, 3-8 membered cyclic alkane groups, 3-8 membered oxachain alkane groups, C2-C10 chain alkenyl groups, C2-C10 oxachain alkenyl groups, 3-8 membered cyclic alkenyl groups, C2-C10 chain alkyne groups, C2-C10 oxachain alkyne groups, 3-8 membered cyclic alkyne groups, 6-10 membered aromatic hydrocarbon groups, 6-10 membered aryloxy groups, 5-10 membered heteroaromatic hydrocarbon groups, and the aforementioned groups being replaced by R a The substituted group is one or more combinations thereof, and at least one of R2 and R3 includes a C2-C10 chain olefin group, a C2-C10 oxochain olefin group, a C2-C10 chain alkyne group, a C2-C10 oxochain alkyne group, a 3-8 membered cyclic olefin group, a 3-8 membered cyclic alkyne group, a 6-10 membered aromatic hydrocarbon group, a 6-10 membered aryloxy group, a 5-10 membered heteroaromatic hydrocarbon group, and the aforementioned group is replaced by R a The substituted groups are one or more combinations thereof; optionally, R2 and R3 independently comprise C1-C5 chain alkane groups, C1-C5 oxachain alkane groups, C2-C5 chain alkenyl groups, C2-C5 oxachain alkenyl groups, 3-6 membered cyclic alkenyl groups, C2-C5 chain alkyne groups, C2-C5 oxachain alkyne groups, 3-6 membered cyclic alkyne groups, 6-10 membered aromatic hydrocarbon groups, 6-10 membered aryloxy groups, 5-10 membered heteroaromatic hydrocarbon groups, and the aforementioned groups being replaced by R. a The substituted group is one or more of the following combinations, and at least one of R2 and R3 includes a C2-C5 chain olefin group, a C2-C5 oxochain olefin group, a phenyl group, and the aforementioned group is replaced by R. aThe substituted group is one or more combinations thereof; R4 includes C2-C10 subchain olefinic groups, C2-C10 oxoheterochain olefinic groups, C2-C10 subchain alkynyl groups, C2-C10 oxoheterochain alkynyl groups, 3-8 membered subcyclic olefinic groups, 3-8 membered subcyclic alkynyl groups, 6-10 membered aromatic hydrocarbon groups, 5-10 membered heteroaromatic hydrocarbon groups, and the aforementioned groups being replaced by R. a The substituted group is one or more combinations thereof; optionally, R4 includes C2-C5 subchain olefinic group, C2-C5 oxyheterochain olefinic group, phenyl, biphenyl, and the aforementioned groups being replaced by R. a One or more of the substituted groups; R a It includes one or more combinations of fluorine atoms, chlorine atoms, bromine atoms, hydroxyl groups, and amino groups.

[0053] In any embodiment, the second coating material comprises one or more of the following organic compounds and their respective alkali metal salts:

[0054]

[0055]

[0056]

[0057] Optionally, the second coating material comprises one or more of the following organic compounds and their respective alkali metal salts:

[0058]

[0059] The coating layer comprises both a first coating material and a second coating material. The first coating material has low steric hindrance, which can reduce the interfacial impedance of the battery. The second coating material contains conjugated π bonds in its molecular structure, which facilitates the formation of organic compounds at the interface, thereby improving interfacial stability. Therefore, when the coating layer comprises both a first coating material and a second coating material, the battery can exhibit better high-temperature cycle performance and high-temperature storage performance.

[0060] In any embodiment, the coating layer comprises one or more of the organic compound of formula (3) and its alkali metal salt.

[0061] Optionally, the coating material comprises one or more of the following organic compounds and their respective alkali metal salts:

[0062]

[0063]

[0064] When the coating material is within the above range, the coating material and the core material can form a better adsorption effect, which can further improve the surface stability of the core material, further reduce the interaction between the core material and the electrolyte, and further improve the high-temperature cycle performance and high-temperature storage performance of the battery.

[0065] In any embodiment, the weight content of the coating layer is 0.01%-1%, optionally 0.1%-0.5%, based on the total weight of the composite cathode material. When the weight content of the coating layer is within the above range, the adsorption between the coating layer material and the core material can be improved, the surface stability of the core material can be enhanced, and the interaction between the core material and the electrolyte can be reduced; it can also enable the composite cathode material to have a higher specific capacity.

[0066] In any embodiment, the coating layer covers 80%-100% of the surface of the core. This enhances the adsorption between the coating layer material and the core material, improves the surface stability of the core material, and reduces the interaction between the core material and the electrolyte.

[0067] A second aspect of this application provides a method for preparing a composite cathode material according to the first aspect of this application, comprising the following steps: providing a core material, wherein the core material includes a cathode active material; providing a coating material, wherein the coating material includes one or more of boric acid, an organic compound having a -B-OH group, an organic compound having a -B-(OH)2 group, and their respective alkali metal salts; stirring and mixing the core material and the coating material uniformly in the presence of a solvent, and drying to obtain a composite cathode material, wherein the composite cathode material includes a core and a coating layer located on at least a portion of the surface of the core.

[0068] The method for preparing composite cathode materials provided in this application is simple, low-cost, and suitable for large-scale production.

[0069] In any embodiment, in the step of stirring and mixing the core material and the coating material uniformly in the presence of a solvent, and then drying to obtain the composite cathode material, the stirring and mixing temperature is 0℃-100℃, and can be selected as 50℃-80℃.

[0070] In any embodiment, in the step of stirring and mixing the core material and the coating material uniformly in the presence of a solvent, and then drying to obtain the composite cathode material, the stirring and mixing time is 0.5h-12h, or optionally 1h-6h.

[0071] In any embodiment, in the step of stirring and mixing the core material and the coating material uniformly in the presence of a solvent, and then drying to obtain the composite cathode material, the solvent includes one or more of water, alcohol, ether, ester, and ketone.

[0072] In any embodiment, in the step of stirring and mixing the core material and the coating material uniformly in the presence of a solvent, and then drying to obtain the composite cathode material, the drying temperature is 40℃-80℃, and can be selected as 50℃-60℃.

[0073] In any embodiment, in the step of stirring and mixing the core material and the coating material evenly in the presence of a solvent, and then drying to obtain the composite cathode material, the drying time is 4h-24h, and can be selected as 6h-12h.

[0074] A third aspect of this application provides a positive electrode sheet, including a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector, wherein the positive electrode film layer includes a composite positive electrode material of the first aspect of this application or a composite positive electrode material prepared by the method of the second aspect of this application.

[0075] In any embodiment, the weight content of the composite positive electrode material in the positive electrode film layer is 50%-99%, optionally 80%-99%, based on the total weight of the positive electrode film layer.

[0076] The fourth aspect of this application provides a battery including the positive electrode sheet of the third aspect of this application.

[0077] The fifth aspect of this application provides an electrical device, including the battery of the fourth aspect of this application.

[0078] The electrical device of this application includes the battery provided in this application, and therefore has at least the same advantages as the battery. Attached Figure Description

[0079] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly described 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 the drawings without creative effort.

[0080] Figure 1 This is a schematic diagram of one embodiment of the battery cell of this application.

[0081] Figure 2 yes Figure 1 An exploded view of the implementation method of the battery cell.

[0082] Figure 3This is a schematic diagram of one embodiment of the battery module of this application.

[0083] Figure 4 This is a schematic diagram of one embodiment of the battery pack of this application.

[0084] Figure 5 yes Figure 4 An exploded view of an embodiment of the battery pack shown.

[0085] Figure 6 This is a schematic diagram of one embodiment of an electrical device that uses the battery of this application as a power source.

[0086] The accompanying drawings are not necessarily drawn to scale. The reference numerals are explained as follows: 1 Battery pack, 2 Upper casing, 3 Lower casing, 4 Battery module, 5 Individual battery cell, 51 Housing, 52 Electrode assembly, 53 Cover plate. Detailed Implementation

[0087] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the composite cathode material, its preparation method, cathode sheet, battery, and power device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0088] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0089] Unless otherwise specified, all embodiments and optional embodiments of this application may be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of this application.

[0090] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions, and such technical solutions shall be deemed to be included in the disclosure of this application.

[0091] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), indicating that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0092] In this application, the terms "multiple" or "various" refer to two or more kinds.

[0093] Unless otherwise stated, the terms used in this application have the common meanings as commonly understood by those skilled in the art.

[0094] Unless otherwise stated, the values ​​of the parameters mentioned in this application can be determined using various testing methods commonly used in the art, for example, according to the testing methods given in the embodiments of this application. Unless otherwise stated, the test temperature for each parameter is 25°C.

[0095] In this application, when a group is described as "chain-like", the group can be a straight-chain structure or a branched-chain structure.

[0096] In this application, when a group is described as "oxa", it means that one or more carbon atoms in the main chain or ring of the group are replaced by oxygen atoms. For example, oxa-chain alkane group refers to a group in which one or more carbon atoms in the main chain of a chain alkane group are replaced by oxygen atoms, and oxa-cyclic alkane group refers to a group in which one or more carbon atoms in the ring of a cyclic alkane group are replaced by oxygen atoms.

[0097] In this application, the term "heteroaromatic hydrocarbon group" refers to a cyclic group that is aromatic and contains heteroatoms, which may include one or more of N, S, and O.

[0098] In this application, when a cyclic group is described as having several "members", it indicates that the ring of the cyclic group has a certain number of atoms (here, the atoms on the ring include both carbon atoms and heteroatoms). For example, a 3-8 membered cyclic alkane group indicates that the cyclic alkane group has 3-8 carbon atoms on its ring; a 3-8 membered oxocyclic alkane group indicates that the sum of the number of carbon atoms and oxygen atoms on the ring of the oxocyclic alkane group is 3-8; and a 5-12 membered heteroaromatic group indicates that the sum of the number of carbon atoms and heteroatoms on the ring of the heteroaromatic group is 5-12.

[0099] In various embodiments, the C1-C20 chain alkane group, i.e., the chain alkane group, may contain 1-20 carbon atoms. Other descriptive methods have a similar meaning.

[0100] Throughout this specification, substituents of compounds are disclosed by groups or ranges. It is expressly anticipated that such descriptions include each individual subcombination of members of these groups and ranges. For example, it is expressly anticipated that the term "C1-C6 chain alkane group" individually discloses C1, C2, C3, C4, C5, C6, C1-C6, C1-C5, C1-C4, C1-C3, C1-C2, C2-C6, C2-C5, C2-C4, C2-C3, C3-C6, C3-C5, C3-C4, C4-C6, C4-C5, C5-C6 chain alkane groups. As other examples, it is expressly anticipated that integers ranging from 3 to 10 individually disclose 3, 4, 5, 6, 7, 8, 9, and 10. Accordingly, other groups or ranges may be expressly anticipated.

[0101] The battery mentioned in the embodiments of this application can be a single physical module comprising one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in this application can include battery cells, battery modules, or battery packs.

[0102] A battery cell is the smallest unit that makes up a battery, and it can independently perform the functions of charging and discharging. A battery cell can be cylindrical, cuboid, or other shapes, etc., and the embodiments of this application are not limited in this respect. Figure 1 The example shown is a rectangular battery cell 5.

[0103] When there are multiple battery cells, they are connected in series, parallel, or mixed via a busbar. In some embodiments, the battery can be a battery module; when there are multiple battery cells, they are arranged and fixed to form a battery module. In some embodiments, the battery can be a battery pack, which includes a housing and battery cells, with the battery cells or battery modules housed within the housing. In some embodiments, the housing can be part of the vehicle's chassis structure. For example, a portion of the housing can be at least part of the vehicle's floor, or a portion of the housing can be at least part of the vehicle's crossbeams and longitudinal beams.

[0104] In some embodiments, the battery can be an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0105] A single battery cell generally includes an electrode assembly and an electrolyte. The electrode assembly typically includes a positive electrode and a negative electrode. The electrode assembly can be a wound structure or a stacked structure, and the embodiments of this application are not limited in this regard.

[0106] The battery cell may also include an outer packaging, which can be used to encapsulate the electrode components and electrolyte. The outer packaging can be a rigid shell, such as a hard plastic shell, aluminum shell, or steel shell. The outer packaging can also be a flexible package, such as a pouch-type flexible package. The material of the flexible package can be plastic, such as one or more of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0107] In some embodiments, such as Figure 2 As shown, the outer packaging may include a housing 51 and a cover 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates enclosing a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover 53 is used to cover the opening to close the receiving cavity. Electrode assemblies 52 are encapsulated in the receiving cavity. The number of electrode assemblies 52 contained in the battery cell 5 may be one or more, and can be adjusted according to requirements.

[0108] In some embodiments, individual battery cells can be assembled into a battery module, and the number of individual battery cells contained in the battery module can be multiple, the specific number of which can be adjusted according to the application and capacity of the battery module. Figure 3 This is a schematic diagram of battery module 4 as an example. Figure 3 As shown, in battery module 4, multiple battery cells 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other manner. Furthermore, these multiple battery cells 5 can be fixed in place using fasteners.

[0109] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple battery cells 5 are received.

[0110] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0111] Figure 4 and Figure 5 This is a schematic diagram of battery pack 1 as an example. Figure 4 and Figure 5As shown, the battery pack 1 may include a housing and multiple battery modules 4 disposed within the housing. The housing includes an upper housing 2 and a lower housing 3. The upper housing 2 covers the lower housing 3, forming a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the housing.

[0112] The battery provided in the embodiments of this application may be a lithium battery, such as a lithium-ion battery or a lithium metal battery, but the embodiments of this application are not limited to this.

[0113] The composite cathode material provided in this application includes a core and a coating layer located on at least a portion of the surface of the core. The core includes a cathode active material, and the coating layer includes one or more of boric acid (H3BO3), an organic compound having a -B-OH group, an organic compound having a -B-(OH)2 group, and their respective alkali metal salts.

[0114] Alkali metal salts of boric acid refer to boric acid molecules in which the -B-OH group is partially or completely replaced by -B-OMe, where Me represents alkali metal.

[0115] Alkali metal salts of organic compounds containing -B-OH groups refer to organic compounds in which the -B-OH groups in the molecular structure are partially or completely replaced by -B-OMe groups, where Me represents alkali metal.

[0116] Alkali metal salts of organic compounds containing the -B-(OH)2 group refer to organic compounds in which the -B-(OH)2 group in the molecular structure is partially or completely replaced by the -B-OMe group, where Me represents alkali metal.

[0117] Optionally, the above-mentioned alkali metal salts include lithium salts.

[0118] Compared to traditional coating materials (such as oxide particles), the coating material on the surface of the core material of the composite cathode material provided in this application includes boric acid, organic compound molecules, and their alkali metal salts. This allows the coating material to form a uniform coating layer on the surface of the core material, thereby reducing direct contact between the core material and the electrolyte and minimizing side reactions at the cathode-electrolyte interface. Furthermore, the coating material on the surface of the core material of the composite cathode material provided in this application also functions similarly to a solid electrolyte interface protective film, and its low impedance improves the surface stability of the core material without affecting the lithium-ion transport rate. This also contributes to the composite cathode material having higher capacity and higher initial coulombic efficiency.

[0119] Traditional coating materials (such as oxide particles) are typically physical coatings, which cannot passivate the low-coordinate oxygen atoms and transition metal atoms on the surface of the core material. This makes it difficult to reduce the interaction between the core material and the electrolyte, and consequently, to reduce side reactions at the cathode-electrolyte interface. In particular, side reactions between the electrolyte and low-coordinate oxygen atoms and transition metal atoms increase at high temperatures, further reducing the interfacial stability of the core material and resulting in poorer long-term battery stability.

[0120] The coating layer of the composite cathode material provided in this application includes one or more of boric acid, organic compounds with -B-OH groups, organic compounds with -B-(OH)2 groups, and their respective alkali metal salts. The B atoms in the coating layer can form BO covalent bonds with the low-coordinate oxygen atoms on the surface of the core material, thereby stabilizing the low-coordinate oxygen atoms on the surface of the core material. The -OH and -OMe (Me represents alkali metal) in the coating layer can form bonds with the low-coordinate transition metal atoms on the surface of the core material to achieve the purpose of stabilizing the low-coordinate transition metal atoms.

[0121] Therefore, the coating material can form directional adsorption with the core material, thereby improving the surface stability of the core material and reducing the interaction between the core material and the electrolyte. This can improve the long-term stability of the battery under high temperature conditions, giving the battery good high-temperature cycle performance and high-temperature storage performance.

[0122] In some embodiments, the coating layer is a monolayer.

[0123] In some embodiments, the thickness of the coating layer can be 0.2 nm to 3 nm, for example, 0.2 nm, 0.4 nm, 0.6 nm, 0.8 nm, 1 nm, 1.2 nm, 1.4 nm, 1.6 nm, 1.8 nm, 2 nm, 2.2 nm, 2.4 nm, 2.6 nm, 2.8 nm, 3 nm, or any range of the above values. When the thickness of the coating layer is within the above range, the adsorption between the coating layer material and the core material can be enhanced, the surface stability of the core material can be improved, and the interaction between the core material and the electrolyte can be reduced; it can also reduce the interaction between the core material and the electrolyte without affecting the capacity of the composite cathode material.

[0124] In some embodiments, the adsorption energy between the coating layer and the core is greater than the adsorption energy between the ethylene carbonate compound and the core. Ethylene carbonate is a commonly used organic solvent in electrolytes. By adjusting the adsorption energy between the coating layer and the core to be greater than that between the ethylene carbonate compound and the core, side reactions between the electrolyte and low-coordinate oxygen atoms and transition metal atoms can be reduced. This improves the surface stability of the core material, reduces the interaction between the core material and the electrolyte, and consequently enhances the long-term stability of the battery under high-temperature conditions, resulting in good high-temperature cycle performance and high-temperature storage performance.

[0125] The adsorption energies between the coating layer and the core, and between the ethylene carbonate compound and the core, can be calculated using density functional theory with the Vienna Ab initio Simulation Package (VASP). The Perdew-Burke-Ernzerhof (PBE) algorithm is used to approximate the exchange-related functionals. The interaction between electrons and the core is studied using the projection-enhanced wave (PAW) method. The transition metals in the core material are corrected using Hubbard U parameters.

[0126] The adsorption energy formula is as follows:

[0127] E add1 = E1 - E2 - E3, where E1 is the energy of the core and the outer shell, E2 is the energy of the core, and E3 is the energy of the outer shell. add1 This represents the adsorption energy between the coating layer and the core.

[0128] E add2 =E4-E5-E6, where E4 is the energy of the core and the ethylene carbonate compound, E5 is the energy of the core, and E6 is the energy of the ethylene carbonate compound. add2 This represents the adsorption energy between the ethylene carbonate compound and the core.

[0129] In some embodiments, the core includes a positive electrode active material, which may include one or more of the following: spinel-structured lithium manganese oxide, layered lithium-containing transition metal oxide, and lithium-containing phosphate.

[0130] Optionally, the spinel-structured lithium manganese oxide may include one or more of LiMn2O4 and its doped materials. The doping element in the LiMn2O4 doped material may be doped at at least one of the Li, Mn, and O sites. The doping element may include, but is not limited to, one or more of Mg, Fe, Al, Co, Zn, Ni, Pt, Ni, Sb, Te, Ti, V, Mo, Nb, B, Si, Ge, Sn, F, S, and Cl.

[0131] Spinel-structured lithium manganese oxide is a promising low-cost, high-energy-density cathode active material. However, spinel-structured lithium manganese oxide has numerous surface oxygen defects and low stability. The Mn content in the bulk phase of spinel-structured lithium manganese oxide during battery charging... 3+ It readily undergoes a disproportionation reaction to generate Mn 4+ and Mn 2+ And the generated Mn 2+ It will dissolve in the electrolyte, Mn 2+ Further reduction reactions and deposition can occur on the negative electrode surface, thereby damaging the structure of the solid electrolyte interfacial film and affecting lithium-ion transport. During battery charging, the entire Mn-O structure of spinel-structured lithium manganese oxide loses electrons. Due to the loss of some electrons, the oxidation activity of oxygen atoms increases, making it easier for oxygen vacancies to be generated in the positive electrode active material, reducing the coordination number of Mn atoms, thus leading to decreased Mn atom stability and increased Mn dissolution. After the oxygen atoms on the surface of the spinel-structured lithium manganese oxide lose some electrons, their oxidation activity increases, making it easier to oxidize the electrolyte. This leads to the generation of H+ at the positive electrode. + H2 is also generated on the surface of the negative electrode, which increases the amount of gas produced by the battery and affects its storage performance. During battery charging, the spinel structure of lithium manganese oxide is also accompanied by the distortion and destruction of its crystal structure, which leads to reduced structural stability, increased difficulty in lithium ion insertion and extraction, and increased capacity decay.

[0132] Currently, methods to improve the stability of spinel-structured lithium manganese oxides, such as oxide coating, increasing grain size, and bulk doping, can enhance the stability of batteries at room temperature. However, their effects on long-term stability and long-term stability at high temperatures are limited. For example, conventional oxide coating materials, due to uneven coating, are prone to hydrogen transfer from organic solvents in the electrolyte. This weakens the Mn-O bond interaction on the surface of the positive electrode active material. Under the catalysis of Mn ions, the electrolyte is more likely to undergo side reactions with the positive electrode surface, leading to insufficient long-term battery stability. Furthermore, the long-term stability of batteries at high temperatures (especially high-temperature cycling performance and high-temperature storage performance) is not positively correlated with the stability at room temperature (e.g., room-temperature cycling performance and room-temperature storage performance). In other words, even if the room-temperature cycling performance or room-temperature storage performance of the battery is significantly improved by modifying the spinel-structured lithium manganese oxide, the high-temperature cycling performance and high-temperature storage performance may still not improve or may even deteriorate.

[0133] The coating material of the composite cathode material provided in this application embodiment can form directional adsorption with spinel-structured lithium manganese oxide, thereby improving the surface stability of spinel-structured lithium manganese oxide and reducing the interaction between spinel-structured lithium manganese oxide and electrolyte, thus improving the long-term stability of the battery under high temperature environment, and enabling the battery to have good high-temperature cycle performance and high-temperature storage performance.

[0134] Optionally, the layered lithium-containing transition metal oxide may include one or more of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their respective doped materials. The doping element in the lithium nickel cobalt manganese oxide doping material may be doped at at least one of the Li, Ni, Co, Mn, and O sites. The doping element in the lithium nickel cobalt aluminum oxide doping material may be doped at at least one of the Li, Ni, Co, Al, and O sites. The doping element may include, but is not limited to, one or more of Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, B, N, F, S, and Cl.

[0135] Optionally, the lithium-containing phosphate may include one or more of lithium iron phosphate, lithium manganese iron phosphate, and their respective doped materials. The doping element in the lithium iron phosphate doped material may be doped at at least one of the Li, Fe, P, and O sites. The doping element in the lithium manganese iron phosphate doped material may be doped at at least one of the Li, Fe, Mn, P, and O sites. The doping element may include, but is not limited to, one or more of Nb, Zr, Zn, Cu, Cr, Mg, V, Ti, F, S, and Cl.

[0136] In some embodiments, the coating layer may include boric acid, an organic compound of formula (1) to formula (3), and one or more of their respective alkali metal salts.

[0137]

[0138]

[0139] R1, R2, and R3 independently comprise C1-C20 chain alkane groups, C1-C20 oxochain alkane groups, 3-8 membered cyclic alkane groups, 3-8 membered oxochain alkane groups, C2-C20 chain alkenyl groups, C2-C20 oxochain alkenyl groups, 3-8 membered cyclic alkenyl groups, C2-C20 chain alkyne groups, C2-C20 oxochain alkyne groups, 3-8 membered cyclic alkyne groups, 6-18 membered aromatic hydrocarbon groups, 6-18 membered aryloxy groups, 5-12 membered heteroaromatic hydrocarbon groups, and the aforementioned groups being modified by R. a One or more of the substituted groups, in combination.

[0140] R4 includes single bonds, C1-C20 subchain alkane groups, C1-C20 oxoheterochain alkane groups, 3-8 membered subcyclic alkane groups, 3-8 membered oxoheterochain alkane groups, C2-C20 subchain olefin groups, C2-C20 oxoheterochain olefin groups, 3-8 membered subcyclic olefin groups, C2-C20 subchain alkyne groups, C2-C20 oxoheterochain alkyne groups, 3-8 membered subcyclic alkyne groups, 6-18 membered aromatic hydrocarbon groups, 5-12 membered heteroaromatic hydrocarbon groups, and the aforementioned groups being R a One or more of the substituted groups, in combination.

[0141] R a It includes one or more combinations of halogen atoms, hydroxyl groups, amino groups, phenyl groups, cyclohexyl groups, C1-C6 chain alkane groups and their halogenated groups, C2-C6 chain olefin groups and their halogenated groups, C1-C6 oxochain alkane groups and their halogenated groups, and C2-C6 oxochain olefin groups and their halogenated groups.

[0142] When the organic compounds shown in formulas (1) to (3) are within the above range, they are conducive to the formation of good adsorption between the coating material and the core material, thereby improving the surface stability of the core material, reducing the interaction between the core material and the electrolyte, and thus improving the high-temperature cycle performance and high-temperature storage performance of the battery.

[0143] In some embodiments, R1, R2, and R3 independently comprise C1-C10 chain alkane groups, C1-C10 oxachain alkane groups, 3-8 membered cyclic alkane groups, 3-8 membered oxachain alkane groups, C2-C10 chain alkenyl groups, C2-C10 oxachain alkenyl groups, 3-8 membered cyclic alkenyl groups, C2-C10 chain alkyne groups, C2-C10 oxachain alkyne groups, 3-8 membered cyclic alkyne groups, 6-10 membered aromatic hydrocarbon groups, 6-10 membered aryloxy groups, 5-10 membered heteroaromatic hydrocarbon groups, and the aforementioned groups are separated by R. a One or more of the substituted groups, in combination.

[0144] When R1, R2, and R3 are within the above range, the steric hindrance of organic compound molecules can be further reduced, the battery interface impedance can be reduced, the adsorption between organic compound molecules and core materials can be further enhanced, the surface stability of core materials can be further improved, the interaction between core materials and electrolyte can be further reduced, and the high-temperature cycle performance and high-temperature storage performance of the battery can be further improved.

[0145] In some embodiments, R4 includes a single bond, a C1-C10 subchain alkane group, a C1-C10 oxoheterochain alkane group, a 3-8 member subcyclic alkane group, a 3-8 member oxoheterochain alkane group, a C2-C10 subchain olefin group, a C2-C10 oxoheterochain olefin group, a 3-8 member subcyclic olefin group, a C2-C10 subchain alkyne group, a C2-C10 oxoheterochain alkyne group, a 3-8 member subcyclic alkyne group, a 6-10 member aromatic hydrocarbon group, a 5-10 member heteroaromatic hydrocarbon group, and the aforementioned groups being R a One or more of the substituted groups, in combination.

[0146] When R4 is within the above range, it can further reduce the steric hindrance of organic compound molecules, reduce the battery interface impedance, further enhance the adsorption between organic compound molecules and core materials, thereby further improving the surface stability of core materials, further reducing the interaction between core materials and electrolyte, and further improving the high-temperature cycle performance and high-temperature storage performance of the battery.

[0147] In some embodiments, R a It includes one or more combinations of fluorine atoms, chlorine atoms, bromine atoms, hydroxyl groups, amino groups, phenyl groups, cyclohexyl groups, C1-C4 chain alkane groups and their halogenated groups, C2-C4 chain olefin groups and their halogenated groups, C1-C4 oxochain alkane groups and their halogenated groups, and C2-C4 oxochain olefin groups and their halogenated groups.

[0148] In some embodiments, R1, R2, and R3 independently comprise C1-C10 chain alkane groups, C1-C10 oxochain alkane groups, 3-8 membered cyclic alkane groups, 3-8 membered oxocyclic alkane groups, and the aforementioned groups are respectively surrounded by R a One or more of the substituted groups, in combination.

[0149] Optionally, R1, R2, and R3 each independently include a C1-C5 chain alkane group, a C1-C5 oxochain alkane group, a 3-5 membered cyclic alkane group, and the aforementioned groups being replaced by R. a One or more of the substituted groups, in combination.

[0150] Optionally, R a It includes one or more combinations of fluorine atoms, chlorine atoms, bromine atoms, hydroxyl groups, and amino groups.

[0151] When R1, R2, and R3 are within the above range, the steric hindrance of organic compound molecules can be reduced, the battery interface impedance can be reduced, and the adsorption between organic compound molecules and core materials can be further enhanced. This can further improve the surface stability of the core material, further reduce the interaction between the core material and the electrolyte, and further improve the high-temperature cycle performance and high-temperature storage performance of the battery.

[0152] In some embodiments, R4 includes a single bond, a C1-C10 subchain alkane group, a C1-C10 oxyheterochain alkane group, a 3-8 membered subcyclic alkane group, a 3-8 membered oxyheterocyclic alkane group, and the aforementioned groups being R a One or more of the substituted groups, in combination.

[0153] Optionally, R4 includes a single bond, a C1-C5 subchain alkane group, and the aforementioned group being replaced by R. a One or more of the substituted groups, in combination.

[0154] Optionally, R a It includes one or more combinations of fluorine atoms, chlorine atoms, bromine atoms, hydroxyl groups, and amino groups.

[0155] When R4 is within the above range, it can reduce the steric hindrance of organic compound molecules, reduce the battery interface impedance, and further enhance the adsorption between organic compound molecules and core materials. This can further improve the surface stability of core materials, further reduce the interaction between core materials and electrolytes, and further improve the high-temperature cycle performance and high-temperature storage performance of the battery.

[0156] In some embodiments, the coating layer may include one or more of boric acid, organic compounds, and their respective alkali metal salts:

[0157]

[0158]

[0159] Optionally, the coating layer may include one or more of boric acid, organic compounds, and their respective alkali metal salts:

[0160]

[0161] When the coating material is within the above range, it can reduce the battery interface impedance, further enhance the adsorption between the coating material and the core material, thereby further improving the surface stability of the core material, further reducing the interaction between the core material and the electrolyte, and further improving the high-temperature cycle performance and high-temperature storage performance of the battery.

[0162] In some embodiments, R1 includes a C2-C10 chain olefin group, a C2-C10 oxochain olefin group, a C2-C10 chain alkyne group, a C2-C10 oxochain alkyne group, and the aforementioned groups are coated with R. a One or more of the substituted groups, in combination.

[0163] Optionally, R1 includes a C2-C5 chain olefin group, a C2-C5 oxochain olefin group, and the aforementioned groups are replaced by R. a One or more of the substituted groups, in combination.

[0164] Optionally, R a It includes one or more combinations of fluorine atoms, chlorine atoms, bromine atoms, hydroxyl groups, and amino groups.

[0165] When R1 is within the above range, the steric hindrance of organic compound molecules can be reduced, thereby reducing the battery interface impedance. At the same time, the organic compound molecules contain conjugated π bonds, which makes it easier for the organic compound to form a film at the interface, thereby improving the interface stability. This can further enhance the surface stability of the core material, further reduce the interaction between the core material and the electrolyte, and further improve the high-temperature cycle performance and high-temperature storage performance of the battery.

[0166] In some embodiments, R2 and R3 independently comprise C1-C10 chain alkane groups, C1-C10 oxochain alkane groups, 3-8 membered cyclic alkane groups, 3-8 membered oxochain alkane groups, C2-C10 chain alkenyl groups, C2-C10 oxochain alkenyl groups, C2-C10 chain alkyne groups, C2-C10 oxochain alkyne groups, and the aforementioned groups are covered by R. a The substituted group is one or more combinations thereof, and at least one of R2 and R3 includes a C2-C10 chain olefin group, a C2-C10 oxochain olefin group, a C2-C10 chain alkyne group, a C2-C10 oxochain alkyne group, and the aforementioned group is replaced by R a One or more of the substituted groups, in combination.

[0167] Optionally, R2 and R3 independently include C1-C5 chain alkane groups, C1-C5 oxochain alkane groups, C2-C5 chain olefin groups, C2-C5 oxochain olefin groups, C2-C5 chain alkyne groups, C2-C5 oxochain alkyne groups, and the aforementioned groups being converted by R. a The substituted group is one or more of the following combinations, and at least one of R2 and R3 includes a C2-C5 chain olefin group, a C2-C5 oxochain olefin group, and the aforementioned group is replaced by R. a One or more of the substituted groups, in combination.

[0168] Optionally, Ra It includes one or more combinations of fluorine atoms, chlorine atoms, bromine atoms, hydroxyl groups, and amino groups.

[0169] When R2 and R3 are within the above range, the steric hindrance of organic compound molecules can be reduced, thereby reducing the battery interface impedance. At the same time, the organic compound molecules contain conjugated π bonds, which makes it easier for the organic compound to form a film at the interface, thereby improving the interface stability. This can further enhance the surface stability of the core material, further reduce the interaction between the core material and the electrolyte, and further improve the high-temperature cycle performance and high-temperature storage performance of the battery.

[0170] In some embodiments, R4 includes a C2-C10 subchain olefin group, a C2-C10 oxyheterochain olefin group, a C2-C10 subchain alkyne group, a C2-C10 oxyheterochain alkyne group, and the aforementioned groups being R a One or more of the substituted groups, in combination.

[0171] Optionally, R4 includes a C2-C5 subchain olefin group, a C2-C5 oxyheterochain olefin group, and the aforementioned groups are replaced by R. a One or more of the substituted groups, in combination.

[0172] Optionally, R a It includes one or more combinations of fluorine atoms, chlorine atoms, bromine atoms, hydroxyl groups, and amino groups.

[0173] When R4 is within the above range, it can reduce the steric hindrance of organic compound molecules and reduce the battery interface impedance. At the same time, the organic compound molecules contain conjugated π bonds, which makes it easy for organic compounds to form films at the interface, thereby improving the interface stability. This can further enhance the surface stability of the core material, further reduce the interaction between the core material and the electrolyte, and further improve the high-temperature cycle performance and high-temperature storage performance of the battery.

[0174] In some embodiments, the coating layer may include one or more of the following organic compounds and their respective alkali metal salts:

[0175]

[0176] Optionally, the coating layer may include one or more of the following organic compounds and their respective alkali metal salts:

[0177]

[0178] When the coating material is within the above range, it can reduce the battery interface impedance, further improve the surface stability of the core material, further reduce the interaction between the core material and the electrolyte, and further improve the high-temperature cycle performance and high-temperature storage performance of the battery.

[0179] In some embodiments, R1 comprises a 3-8 membered cyclic olefinic group, a 3-8 membered cyclic alkyneic group, a 6-10 membered aromatic hydrocarbon group, a 6-10 membered aryloxy group, a 5-10 membered heteroaromatic hydrocarbon group, and the aforementioned groups being coated with R. a One or more of the substituted groups, in combination.

[0180] Optionally, R1 comprises a 5-6 membered cyclic olefinic group, phenyl, phenoxy, pyridyl, pyrimidinyl, benzodioxane, benzothiophene, triphenylamine, and the aforementioned groups being converted by R. a One or more of the substituted groups, in combination.

[0181] When R1 is within the above range, the organic compound contains conjugated π bonds in its molecular structure, which makes it easier for the organic compound to form a film at the interface, thereby improving the interface stability. This can further enhance the surface stability of the core material, further reduce the interaction between the core material and the electrolyte, and further improve the high-temperature cycle performance and high-temperature storage performance of the battery.

[0182] In some embodiments, R2 and R3 independently comprise C1-C10 chain alkane groups, C1-C10 oxochain alkane groups, 3-8 membered cyclic alkane groups, 3-8 membered oxochain alkane groups, C2-C10 chain alkenyl groups, C2-C10 oxochain alkenyl groups, 3-8 membered cyclic alkenyl groups, C2-C10 chain alkyne groups, C2-C10 oxochain alkyne groups, 3-8 membered cyclic alkyne groups, 6-10 membered aromatic hydrocarbon groups, 6-10 membered aryloxy groups, 5-10 membered heteroaromatic hydrocarbon groups, and the aforementioned groups are separated by R. a The substituted groups are one or more combinations thereof, and at least one of R2 and R3 includes a 3-8 membered cyclic olefinic group, a 3-8 membered cyclic alkynyl group, a 6-10 membered aromatic hydrocarbon group, a 6-10 membered aryloxy group, a 5-10 membered heteroaromatic hydrocarbon group, and the aforementioned groups are replaced by R. a One or more of the substituted groups, in combination.

[0183] Optionally, R2 and R3 independently include C1-C5 chain alkane groups, C1-C5 oxochain alkane groups, C2-C5 chain olefin groups, C2-C5 oxochain olefin groups, 3-6 membered cyclic olefin groups, C2-C5 chain alkyne groups, C2-C5 oxochain alkyne groups, 3-6 membered cyclic alkyne groups, 6-10 membered aromatic hydrocarbon groups, 6-10 membered aryloxy groups, 5-10 membered heteroaromatic hydrocarbon groups, and the aforementioned groups being converted by R. aA combination of one or more of the substituted groups, and at least one of R2 and R3 includes a phenyl group and the aforementioned group is replaced by R. a One or more of the substituted groups, in combination.

[0184] When R2 and R3 are within the above range, the organic compound contains conjugated π bonds in its molecular structure, which makes it easier for the organic compound to form a film at the interface, thereby improving the interface stability. This can further enhance the surface stability of the core material, further reduce the interaction between the core material and the electrolyte, and further improve the high-temperature cycle performance and high-temperature storage performance of the battery.

[0185] In some embodiments, R4 comprises a 3-8 membered subcyclic olefinic group, a 3-8 membered subcyclic alkyneic group, a 6-10 membered aromatic hydrocarbonic group, a 5-10 membered heteroaromatic hydrocarbonic group, and the aforementioned groups being replaced by R. a One or more of the substituted groups, in combination.

[0186] Optionally, R4 includes phenyl, biphenyl, and the aforementioned groups being replaced by R. a One or more of the substituted groups, in combination.

[0187] When R4 is within the above range, the organic compound contains conjugated π bonds in its molecular structure, which makes it easier for the organic compound to form a film at the interface, thereby improving the interface stability. This can further enhance the surface stability of the core material, further reduce the interaction between the core material and the electrolyte, and further improve the high-temperature cycle performance and high-temperature storage performance of the battery.

[0188] In some embodiments, the coating layer may include one or more of the following organic compounds and their respective alkali metal salts:

[0189]

[0190]

[0191]

[0192] Optionally, the coating layer may include one or more of the following organic compounds and their respective alkali metal salts:

[0193]

[0194] When the coating material is within the above range, it can further improve the surface stability of the core material, further reduce the interaction between the core material and the electrolyte, and further improve the high-temperature cycle performance and high-temperature storage performance of the battery.

[0195] In some embodiments, the covering layer includes a first covering layer material and a second covering layer material.

[0196] The first coating material may include boric acid, organic compounds of formulas (1) to (3) above, and one or more of their respective alkali metal salts.

[0197] R1, R2, and R3 independently include C1-C10 chain alkane groups, C1-C10 oxochain alkane groups, 3-8 membered cyclic alkane groups, 3-8 membered oxocyclic alkane groups, and the aforementioned groups being replaced by R. a One or more of the substituted groups, in combination.

[0198] Optionally, R1, R2, and R3 each independently include a C1-C5 chain alkane group, a C1-C5 oxochain alkane group, a 3-5 membered cyclic alkane group, and the aforementioned groups being replaced by R. a One or more of the substituted groups, in combination.

[0199] Optionally, R a It includes one or more combinations of fluorine atoms, chlorine atoms, bromine atoms, hydroxyl groups, and amino groups.

[0200] R4 includes single bonds, C1-C10 subchain alkane groups, C1-C10 oxoheterochain alkane groups, 3-8 membered subcyclic alkane groups, 3-8 membered oxoheterocyclic alkane groups, and the aforementioned groups being R a One or more of the substituted groups, in combination.

[0201] Optionally, R4 includes a single bond, a C1-C5 subchain alkane group, and the aforementioned group being replaced by R. a One or more of the substituted groups, in combination.

[0202] Optionally, R a It includes one or more combinations of fluorine atoms, chlorine atoms, bromine atoms, hydroxyl groups, and amino groups.

[0203] Optionally, the first coating material may include one or more of boric acid, organic compounds, and their respective alkali metal salts:

[0204]

[0205]

[0206] Alternatively, the first coating material may include one or more of boric acid, organic compounds, and their respective alkali metal salts:

[0207]

[0208]

[0209] The second coating material may include one or more of the organic compounds shown in formulas (1) to (3) and their respective alkali metal salts.

[0210] R1 includes C2-C10 chain olefin groups, C2-C10 oxochain olefin groups, C2-C10 chain alkyne groups, C2-C10 oxochain alkyne groups, 3-8 membered cyclic olefin groups, 3-8 membered cyclic alkyne groups, 6-10 membered aromatic hydrocarbon groups, 6-10 membered aryloxy groups, 5-10 membered heteroaromatic hydrocarbon groups, and the aforementioned groups being R a One or more of the substituted groups, in combination.

[0211] Optionally, R1 includes C2-C5 chain olefins, C2-C5 oxochain olefins, 5-6 membered cyclic olefins, phenyl, phenoxy, pyridyl, pyrimidinyl, benzodioxane, benzothiophene, triphenylamine, and the aforementioned groups being converted by R. a One or more of the substituted groups, in combination.

[0212] Optionally, R a It includes one or more combinations of fluorine atoms, chlorine atoms, bromine atoms, hydroxyl groups, and amino groups.

[0213] R2 and R3 independently comprise C1-C10 chain alkane groups, C1-C10 oxochain alkane groups, 3-8 membered cyclic alkane groups, 3-8 membered oxochain alkane groups, C2-C10 chain alkenyl groups, C2-C10 oxochain alkenyl groups, 3-8 membered cyclic alkenyl groups, C2-C10 chain alkyne groups, C2-C10 oxochain alkyne groups, 3-8 membered cyclic alkyne groups, 6-10 membered aromatic hydrocarbon groups, 6-10 membered aryloxy groups, 5-10 membered heteroaromatic hydrocarbon groups, and the aforementioned groups being converted by R. a The substituted group is one or more combinations thereof, and at least one of R2 and R3 includes a C2-C10 chain olefin group, a C2-C10 oxochain olefin group, a C2-C10 chain alkyne group, a C2-C10 oxochain alkyne group, a 3-8 membered cyclic olefin group, a 3-8 membered cyclic alkyne group, a 6-10 membered aromatic hydrocarbon group, a 6-10 membered aryloxy group, a 5-10 membered heteroaromatic hydrocarbon group, and the aforementioned group is replaced by R a One or more of the substituted groups, in combination.

[0214] Optionally, R2 and R3 independently include C1-C5 chain alkane groups, C1-C5 oxochain alkane groups, C2-C5 chain olefin groups, C2-C5 oxochain olefin groups, 3-6 membered cyclic olefin groups, C2-C5 chain alkyne groups, C2-C5 oxochain alkyne groups, 3-6 membered cyclic alkyne groups, 6-10 membered aromatic hydrocarbon groups, 6-10 membered aryloxy groups, 5-10 membered heteroaromatic hydrocarbon groups, and the aforementioned groups being converted by R. aThe substituted group is one or more of the following combinations, and at least one of R2 and R3 includes a C2-C5 chain olefin group, a C2-C5 oxochain olefin group, a phenyl group, and the aforementioned group is replaced by R. a One or more of the substituted groups, in combination.

[0215] Optionally, R a It includes one or more combinations of fluorine atoms, chlorine atoms, bromine atoms, hydroxyl groups, and amino groups.

[0216] R4 includes C2-C10 subchain olefinic groups, C2-C10 oxoheterochain olefinic groups, C2-C10 subchain alkynyl groups, C2-C10 oxoheterochain alkynyl groups, 3-8 membered subcyclic olefinic groups, 3-8 membered subcyclic alkynyl groups, 6-10 membered aromatic hydrocarbon groups, 5-10 membered heteroaromatic hydrocarbon groups, and the aforementioned groups being R a One or more of the substituted groups, in combination.

[0217] Optionally, R4 includes a C2-C5 subchain olefin group, a C2-C5 oxyheterochain olefin group, a phenyl group, a biphenyl group, and the aforementioned groups being replaced by R. a One or more of the substituted groups, in combination.

[0218] Optionally, R a It includes one or more combinations of fluorine atoms, chlorine atoms, bromine atoms, hydroxyl groups, and amino groups.

[0219] Optionally, the second coating material may include one or more of the following organic compounds and their respective alkali metal salts:

[0220]

[0221]

[0222]

[0223] Alternatively, the second coating material may include one or more of the following organic compounds and their respective alkali metal salts:

[0224]

[0225]

[0226] The coating layer comprises both a first coating material and a second coating material. The first coating material has low steric hindrance, which can reduce the interfacial impedance of the battery. The second coating material contains conjugated π bonds in its molecular structure, which facilitates the formation of organic compounds at the interface, thereby improving interfacial stability. Therefore, when the coating layer comprises both a first coating material and a second coating material, the battery can exhibit better high-temperature cycle performance and high-temperature storage performance.

[0227] In some embodiments, the coating layer may include one or more of boric acid, organic compounds of formula (1) and formula (3), and their respective alkali metal salts.

[0228] When the coating material is within the above range, the coating material and the core material can form a better adsorption effect, which can further improve the surface stability of the core material, further reduce the interaction between the core material and the electrolyte, and further improve the high-temperature cycle performance and high-temperature storage performance of the battery.

[0229] In some embodiments, the coating layer may include one or more of the organic compound of formula (3) and its alkali metal salt.

[0230] Optionally, the coating material may include one or more of the following organic compounds and their respective alkali metal salts:

[0231]

[0232]

[0233] When the coating material is within the above range, the coating material and the core material can form a better adsorption effect, which can further improve the surface stability of the core material, further reduce the interaction between the core material and the electrolyte, and further improve the high-temperature cycle performance and high-temperature storage performance of the battery.

[0234] In some embodiments, the weight content of the coating layer can be 0.01%-1%, based on the total weight of the composite cathode material, and can be, for example, 0.01%, 0.02%, 0.05%, 0.1%, 0.15%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, or any range of the above values.

[0235] Optionally, the weight content of the coating layer can be 0.1%-0.5%.

[0236] When the weight content of the coating layer is within the above range, it can enhance the adsorption between the coating layer material and the core material, improve the surface stability of the core material, reduce the interaction between the core material and the electrolyte, and also enable the composite cathode material to have a higher specific capacity.

[0237] In some embodiments, the coating layer may be located on 80%-100% of the surface of the core. This can enhance the adsorption between the coating layer material and the core material, improve the surface stability of the core material, and reduce the interaction between the core material and the electrolyte.

[0238] In some embodiments, the volumetric particle size Dv50 of the composite cathode material can be 3 μm-18 μm, and optionally 5 μm-10 μm. When the volumetric particle size Dv50 of the composite cathode material is within the above range, it is beneficial to improve the transport performance of ions and electrons, thereby improving the cycle performance and / or rate performance of the battery.

[0239] The volumetric distribution particle size Dv50 of composite cathode materials has a well-known meaning in the art, representing the particle size corresponding to a cumulative volume distribution percentage of 50%, and can be determined using instruments and methods known in the art. For example, it can be conveniently determined using a laser particle size analyzer according to GB / T 19077-2016. The testing instrument can be the Mastersizer 2000E laser particle size analyzer from Malvern Instruments Ltd., UK.

[0240] [Preparation Method]

[0241] This application also provides a method for preparing the above-mentioned composite cathode material.

[0242] The method includes the following steps: providing a core material, wherein the core material includes a positive electrode active material; providing a coating material, wherein the coating material includes one or more of boric acid, an organic compound having a -B-OH group, an organic compound having a -B-(OH)2 group, and their respective alkali metal salts; stirring and mixing the core material and the coating material uniformly in the presence of a solvent, and drying to obtain a composite positive electrode material, wherein the composite positive electrode material includes a core and a coating layer located on at least a portion of the surface of the core.

[0243] The method for preparing composite cathode materials provided in this application is simple, low-cost, and suitable for large-scale production.

[0244] In some embodiments, the temperature at which the core material and the coating material are stirred and mixed in the presence of a solvent can be 0°C-100°C, and optionally 50°C-80°C.

[0245] In some embodiments, the stirring time for mixing the core material and the coating material in the presence of a solvent can be 0.5h-12h, or optionally 1h-6h.

[0246] In some embodiments, when the core material and the coating material are stirred in the presence of a solvent, the solvent may include one or more of water, alcohol, ether, ester, and ketone.

[0247] Optionally, the alcohol includes, but is not limited to, one or more of ethanol, methanol, and isopropanol.

[0248] Optionally, the ether includes, but is not limited to, diethyl ether.

[0249] Optionally, the ester includes, but is not limited to, one or more of methyl acetate, ethyl acetate, and propyl acetate.

[0250] Optionally, the ketone includes, but is not limited to, one or more of acetone and methyl ethyl ketone.

[0251] There are no particular limitations on the drying temperature and time, as long as the solvent can be removed. In some embodiments, the drying temperature can be 40°C-80°C, optionally 50°C-60°C. In some embodiments, the drying time can be 4h-24h, optionally 6h-12h.

[0252] The core material can be obtained commercially or prepared according to methods known in the art. In some embodiments, the step of providing a spinel-structured lithium manganese oxide includes the following steps: preparing an aqueous solution of a lithium source, a metal source, and optionally a dopant element source; adding a complexing agent to the obtained aqueous solution to perform a complexation reaction to obtain a gel precursor; and sintering the obtained gel precursor to obtain the core material.

[0253] In some embodiments, the lithium source may be one or more of lithium acetate, carbonate, nitrate, sulfate, hydroxide, and oxide.

[0254] In some embodiments, the metal source includes a manganese source. The manganese source may be one or more of manganese acetate, carbonate, nitrate, sulfate, hydroxide, and oxide.

[0255] In some embodiments, the optional dopant source includes, but is not limited to, one or more of the following: acetate, carbonate, nitrate, sulfate, hydroxide, and oxide of the dopant element.

[0256] In some embodiments, the complexing agent may include, but is not limited to, one or more of citric acid, oxalic acid, glutamic acid, polyvinylidene fluoride, and polyacrylamide.

[0257] In some embodiments, the temperature at which the complexing agent is added to the resulting aqueous solution to carry out the complexing reaction can be 40°C-100°C.

[0258] In some embodiments, the pH value at which the complexing agent is added to the resulting aqueous solution for the complexation reaction can be 7-11.

[0259] In some embodiments, the step of sintering the obtained gel precursor includes a first sintering process and a second sintering process.

[0260] Optionally, the temperature of the first sintering process can be 500℃-800℃.

[0261] Optionally, the sintering time for the first stage can be 6-10 hours.

[0262] Optionally, the temperature of the second sintering process can be 200℃-600℃.

[0263] Optionally, the second sintering process can take 3-6 hours.

[0264] [Positive electrode plate]

[0265] This application also provides a positive electrode sheet.

[0266] The positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector. The positive electrode film layer includes the composite positive electrode material described above or the composite positive electrode material prepared by the method described above in this application.

[0267] In some embodiments, the weight content of the composite cathode material in the cathode film layer can be 50%-99%, optionally 80%-99%, based on the total weight of the cathode film layer.

[0268] The positive current collector has two surfaces opposite each other in its thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0269] In some embodiments, the positive electrode film may optionally include a positive electrode conductive agent. As an example, the positive electrode conductive agent may include, but is not limited to, one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0270] In some embodiments, the positive electrode film layer may optionally include a positive electrode binder. As an example, the positive electrode binder may include, but is not limited to, one or more of the following: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resins, styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, waterborne acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0271] In some embodiments, the positive current collector may be a metal foil or a composite current collector. An example of a metal foil is aluminum foil. The composite current collector may include a polymeric material substrate and a metal material layer formed on at least one surface of the polymeric material substrate. As an example, the metal material may include, but is not limited to, one or more of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As an example, the polymeric material substrate may include, but is not limited to, one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0272] In some embodiments, the positive electrode sheet can be prepared by dispersing a composite positive electrode active material, an optional positive electrode conductive agent, an optional positive electrode binder, and any other components in a solvent and stirring until homogeneous to form a positive electrode slurry; coating the positive electrode slurry onto at least one surface of a positive electrode current collector; and obtaining the positive electrode sheet through processes such as drying and cold pressing. The solvent can be N-methylpyrrolidone (NMP), but is not limited thereto.

[0273] In some embodiments, the positive electrode sheet can also be prepared by the following method: providing a positive electrode slurry, the positive electrode slurry comprising the positive electrode active material as described above; coating the positive electrode slurry onto at least one surface of a positive electrode current collector, and drying to obtain a positive electrode film layer; immersing the positive electrode film layer in a solution comprising the coating layer material as described above, and drying to obtain a positive electrode sheet. This allows the coating layer as described above to be formed on at least a portion of the surface of the positive electrode active material. Optionally, the positive electrode film layer is immersed in a solution comprising the coating layer material as described above, and then dried at 40°C-80°C for 4h-24h to obtain the positive electrode sheet. The positive electrode slurry may also include a positive electrode conductive agent, a positive electrode binder, and any other components. The solvent in the positive electrode slurry may be N-methylpyrrolidone (NMP), but is not limited thereto.

[0274] In some embodiments, the positive electrode sheet can also be prepared by the following method: providing a positive electrode slurry, the positive electrode slurry comprising the above-described positive electrode active material and coating material; coating the positive electrode slurry onto at least one surface of the positive electrode current collector, and drying to obtain the positive electrode sheet. This forms the above-described coating layer on at least a portion of the surface of the positive electrode active material. The positive electrode slurry may also include a positive electrode conductive agent, a positive electrode binder, and any other components. The solvent in the positive electrode slurry may be N-methylpyrrolidone (NMP), but is not limited thereto.

[0275] [Negative electrode plate]

[0276] Each battery cell includes a negative electrode. The structure and composition of the negative electrode can be selected according to the type of battery cell, and the embodiments of this application are not limited in this regard.

[0277] In some embodiments, the negative electrode sheet may include a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector and comprising a negative electrode active material. For example, the negative current collector has two surfaces opposite each other in its thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative current collector.

[0278] The negative electrode active material can be one or more materials known in the art, including but not limited to natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. Silicon-based materials can include, but are not limited to, one or more of elemental silicon, silicon oxide, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials can include, but are not limited to, one or more of elemental tin, tin oxide, and tin alloys. This application is not limited to these materials; other conventionally known materials that can be used as negative electrode active materials for secondary batteries can also be used. These negative electrode active materials can be used alone or in combination of two or more.

[0279] In some embodiments, the negative electrode film layer may optionally include a negative electrode conductive agent. As an example, the negative electrode conductive agent may include, but is not limited to, one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0280] In some embodiments, the negative electrode film layer may optionally include a negative electrode binder. As an example, the negative electrode binder may include, but is not limited to, one or more of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, waterborne acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0281] In some embodiments, the negative electrode film layer may optionally include other additives. As an example, other additives may include thickeners, such as sodium carboxymethyl cellulose (CMC), PTC thermistor materials, etc.

[0282] The negative electrode film is typically formed by coating a negative electrode slurry onto a negative electrode current collector, followed by drying and cold pressing. The negative electrode slurry is usually formed by dispersing the negative electrode active material, optional negative electrode conductive agent, optional negative electrode binder, and other optional additives in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP) or deionized water, but is not limited to these.

[0283] The negative electrode sheet does not exclude other additional functional layers besides the negative electrode film layer. For example, in some embodiments, the negative electrode sheet may also include a conductive undercoat layer (e.g., composed of a conductive agent and an adhesive) sandwiched between the negative electrode current collector and the negative electrode film layer and disposed on the surface of the negative electrode current collector; in some embodiments, the negative electrode sheet may also include a protective layer covering the surface of the negative electrode film layer.

[0284] In some embodiments, the negative electrode sheet may include a negative current collector and a metal layer disposed on at least one surface of the negative current collector. The metal material in the metal layer may include one or more of elemental lithium and lithium alloys. The lithium alloy may be an alloy formed by metallic lithium with other metallic or non-metallic elements. As an example, other metallic elements in the lithium alloy may include one or more of tin, zinc, magnesium, silver, gold, gallium, indium, and platinum, and non-metallic elements in the lithium alloy may include one or more of boron, carbon, and silicon.

[0285] In some embodiments, the negative electrode may be a lithium sheet (foil) or a lithium alloy sheet (foil).

[0286] In some embodiments, the negative electrode may include a negative current collector to assemble a negative electrode-free battery cell.

[0287] In some embodiments, the negative electrode current collector may include a metal foil, a three-dimensional porous current collector, or a composite current collector. Examples of metal foils include copper foil, copper alloy foil, nickel foil, and nickel alloy foil. Examples of three-dimensional porous current collectors include copper mesh, nickel mesh, copper foam, and nickel foam. The composite current collector may include a polymer material substrate and a metal material layer formed on at least one surface of the polymer material substrate. Examples of metal materials include, but are not limited to, one or more of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. Examples of polymer material substrates include, but are not limited to, one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0288] [Electrolytes]

[0289] A single battery cell includes an electrolyte. This application does not impose specific limitations on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte may include one or more selected from solid electrolytes and liquid electrolytes (i.e., electrolyte solutions).

[0290] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.

[0291] In some embodiments, as an example, the electrolyte salt may include, but is not limited to, one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodioxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0292] In some embodiments, the solvent may include, but is not limited to, one or more of ester solvents, sulfone solvents, and ether solvents. For example, the solvent may include, but is not limited to, one or more of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butyl ester carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

[0293] In some embodiments, the electrolyte may optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature performance, additives that improve battery low-temperature power performance, etc.

[0294] [Isolation membrane]

[0295] Battery cells using electrolytes, as well as some battery cells using solid electrolytes, also include a separator. The separator is placed between the positive and negative electrodes, primarily to prevent internal short circuits.

[0296] This application does not impose any particular restrictions on the type of separator membrane; any known porous separator membrane with good chemical and mechanical stability can be selected.

[0297] In some embodiments, the material of the separator may include, but is not limited to, one or more of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer may be the same or different.

[0298] The methods for preparing a single battery cell are well known. In some embodiments, a positive electrode, a separator, a negative electrode, and an electrolyte can be assembled to form a single battery cell. As an example, the positive electrode, separator, and negative electrode can be wound and / or stacked to form an electrode assembly. The electrode assembly is then placed in an outer package, dried, and injected with the electrolyte. After encapsulation, settling, and formation processes, a single battery cell is obtained. Multiple single battery cells can be further connected in series, parallel, or a combination thereof to form a battery module. Multiple battery modules can also be connected in series, parallel, or a combination thereof to form a battery pack. In some embodiments, multiple single battery cells can also be directly assembled into a battery pack.

[0299] Electrical appliances

[0300] This application also provides an electrical device, which includes a battery provided in this application embodiment. The battery is used to provide electrical energy. The battery can be used as the power source of the electrical device or as the energy storage unit of the electrical device. The electrical device can be, but is not limited to, mobile devices (such as mobile phones, tablets, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0301] Electrical devices can choose the specific type of battery according to their usage needs, such as individual battery cells, battery modules, or battery packs.

[0302] Figure 6 This is a schematic diagram of an example electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the device's requirements for high power and high energy density, a battery pack or battery module can be used.

[0303] Another example of an electrical device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a single battery cell as their power source.

[0304] Example

[0305] The following embodiments describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0306] Example 1

[0307] (1) Preparation of composite cathode materials

[0308] Lithium nitrate and manganese nitrate were prepared into an aqueous solution with a molar concentration of 0.5 mol / L according to the target product LiMn2O4. Polyacrylamide complexing agent was added to the above aqueous solution to carry out a complexation reaction, and the temperature of the complexation reaction was controlled at 70℃ and the pH value was controlled at 9 until a gel precursor was obtained. The gel precursor was sintered at 650℃ for 8 h and then sintered at 400℃ for 5 h to obtain LiMn2O4.

[0309] Boric acid was added to an aqueous ethanol solution and stirred until a clear boric acid solution was obtained. The boric acid solution was then mixed with the obtained LiMn2O4 at 60°C for 1 hour with a boric acid coating amount of 0.15% (based on the total weight of the prepared composite cathode material) to obtain a mixed solution. The mixed solution was dried at 80°C for 8 hours to evaporate the solvent, thereby obtaining LiMn2O4 with a boric acid coating layer.

[0310] (2) Preparation of positive electrode sheet

[0311] The above-mentioned composite cathode material is mixed with acetylene black and PVDF at a weight ratio of 8:1:1. Then, an appropriate amount of NMP is added and stirred thoroughly to form a uniform cathode slurry. The cathode slurry is coated onto the cathode current collector aluminum foil, and then dried and cold-pressed to obtain the cathode sheet.

[0312] (3) Battery manufacturing

[0313] In an argon-atmosphere glove box, a lithium sheet was used as the counter electrode, a 1 mol / L LiPF6 solution in a 1:1 volume ratio of ethylene carbonate (EC) and diethyl carbonate (DEC) was used as the electrolyte, and a 12 μm thick polypropylene film was used as the separator. Together with the positive electrode sheet prepared above, they were assembled into a CR2030 coin cell in a coin cell box.

[0314] Examples 2 to 38

[0315] Except for the different types of coating materials used in the preparation of the composite cathode material, the battery fabrication process is the same as in Example 1. Specific parameters are detailed in Table 1.

[0316] The molecular structures of each coating material in Table 1 are shown below.

[0317]

[0318]

[0319]

[0320]

[0321] Examples 39 to 43

[0322] Except for the difference in the weight content of the coating material in the preparation of the composite cathode material, the battery preparation process is the same as in Example 2. Specific parameters and test results are detailed in Table 1.

[0323] Examples 44 to 48

[0324] Except for the difference in the weight content of the coating material in the preparation of the composite cathode material, the battery preparation process is the same as in Example 14. Specific parameters and test results are detailed in Table 1.

[0325] Examples 49 to 53

[0326] Except for the difference in the weight content of the coating material in the preparation of the composite cathode material, the battery preparation process is the same as in Example 33. Specific parameters and test results are detailed in Table 1.

[0327] Comparative Example 1

[0328] Except for the different preparation process of the composite cathode material, the battery preparation process is the same as that in Example 1.

[0329] (1) Preparation of composite cathode materials

[0330] Lithium nitrate and manganese nitrate were prepared into an aqueous solution with a molar concentration of 0.5 mol / L according to the target product LiMn2O4. Polyacrylamide complexing agent was added to the above aqueous solution to carry out a complexation reaction, and the temperature of the complexation reaction was controlled at 70℃ and the pH value was controlled at 9 until a gel precursor was obtained. The gel precursor was sintered at 650℃ for 8 h and then sintered at 400℃ for 5 h to obtain LiMn2O4.

[0331] Comparative Example 2

[0332] Except for the different preparation process of the composite cathode material, the battery preparation process is the same as that in Example 1.

[0333] (1) Preparation of composite cathode materials

[0334] Lithium nitrate and manganese nitrate were prepared into an aqueous solution with a molar concentration of 0.5 mol / L according to the target product LiMn2O4. Polyacrylamide complexing agent was added to the above aqueous solution to carry out a complexation reaction, and the temperature of the complexation reaction was controlled at 70℃ and the pH value at 9 until a gel precursor was obtained. The gel precursor was mixed with a 0.5% (w / w) boric acid aqueous solution and sintered at 650℃ for 8 h, then sintered at 400℃ for 5 h to obtain boron oxide-coated LiMn2O4. The boron oxide coating amount was 0.1%, based on the total weight of the prepared composite cathode material.

[0335] Comparative Example 3

[0336] Except for the different preparation process of the composite cathode material, the battery preparation process is the same as that in Example 1.

[0337] (1) Preparation of composite cathode materials

[0338] Lithium nitrate and manganese nitrate were prepared into an aqueous solution with a molar concentration of 0.5 mol / L according to the target product LiMn2O4. Polyacrylamide complexing agent was added to the above aqueous solution to carry out a complexation reaction, and the temperature of the complexation reaction was controlled at 70℃ and the pH value was controlled at 9 until a gel precursor was obtained. The gel precursor was sintered at 650℃ for 8 h and then sintered at 400℃ for 5 h to obtain LiMn2O4.

[0339] Trimethyl borate was added to ethanol and stirred until a clear trimethyl borate ethanol solution was obtained. The trimethyl borate ethanol solution was mixed with the obtained LiMn2O4 at 60°C for 1 h with a trimethyl borate coating amount of 0.1% (based on the total weight of the prepared composite cathode material) to obtain a mixed solution. The mixed solution was dried at 80°C for 8 h to evaporate the solvent and obtain LiMn2O4 with a trimethyl borate coating layer.

[0340] Test section

[0341] (1) Initial discharge specific capacity and initial coulombic efficiency test

[0342] At 25°C, the coin cell prepared above was charged at a constant current of 0.1C to a voltage of 4.5V, and then charged at a constant voltage to a current of 0.05C. After standing for 5 minutes, the coin cell was discharged at a constant current of 0.1C to a voltage of 3.0V to obtain the initial charging capacity and initial discharging capacity of the coin cell.

[0343] The initial discharge capacity (mAh / g) of the composite cathode material = the initial discharge capacity of the coin cell / the mass of the composite cathode material.

[0344] The initial coulombic efficiency of a coin cell = initial discharge capacity of the coin cell / initial charge capacity of the coin cell.

[0345] (2) High-temperature cycling performance test

[0346] At 45°C, the prepared coin cell was charged at a constant current of 1C to a voltage of 4.5V, and then charged at a constant voltage to a current of 0.05C. After standing for 5 minutes, the coin cell was discharged at a constant current of 1C to a voltage of 3.0V. This constitutes one charge-discharge cycle. The discharge capacity of this cycle is the discharge capacity of the first cycle. The battery was cycled 100 times in the above manner. The capacity retention rate (%) of the coin cell after 100 cycles = discharge capacity of 100 cycles / discharge capacity of the first cycle.

[0347] (3) Mn dissolution test after cycling

[0348] After 100 cycles, the coin cell was disassembled, the negative electrode was removed, and dried. The amount of Mn dissolved, i.e., the weight content of Mn in the negative electrode, was then measured using inductively coupled plasma atomic emission spectrometry (ICP). The testing standard was based on EPA-6010D-2014. An Agilent ICP-OES 730 inductively coupled plasma atomic emission spectrometer was used as the testing instrument.

[0349] (4) High-temperature storage performance test

[0350] At 25°C, the coin cell prepared above was charged at a constant current of 1C to a voltage of 4.5V, and then charged at a constant voltage to a current of 0.05C. After standing for 5 minutes, the coin cell was discharged at a constant current of 1C to a voltage of 3.0V to obtain the discharge capacity of the coin cell before storage.

[0351] At 25°C, the coin cell battery is charged at a constant current of 1C to a voltage of 4.5V, and then charged at a constant voltage to a current of 0.05C. At this point, the coin cell battery is in a fully charged state (100% SOC). The fully charged coin cell battery is stored in a constant temperature chamber at 45°C for 60 days. The coin cell battery is then removed and discharged at a constant current of 1C to a voltage of 3.0V to obtain the discharge capacity of the coin cell battery after storage.

[0352] 60-day capacity retention rate of button cell batteries (%) = discharge capacity after storage / discharge capacity before storage.

[0353] For each of the above performance tests, five coin cells were used for testing, and the average value of the test results was taken. The test results are shown in Table 1.

[0354] Table 1

[0355]

[0356]

[0357] As can be seen from the test results of Examples 1 to 38 and Comparative Example 1, the composite cathode material provided in this application can enable the battery to have high initial coulombic efficiency, high initial discharge specific capacity, and good high-temperature cycle performance and high-temperature storage performance.

[0358] The test results of Comparative Examples 1 and 2 show that traditional oxide coating materials cannot effectively improve the long-term stability of batteries under high-temperature conditions. This is because traditional oxide coating materials are physical coatings, which cannot passivate the low-coordinate oxygen atoms and transition metal atoms on the surface of the core material. This is not conducive to reducing the interaction between the core material and the electrolyte, and thus not conducive to reducing the side reactions at the cathode-electrolyte interface. At the same time, the uneven coating of traditional oxide coating materials makes it easy for H to transfer from the organic solvent in the electrolyte. This weakens the Mn-O bond interaction on the surface of the cathode active material. Under the catalysis of Mn ions, the electrolyte is more likely to undergo side reactions with the cathode surface, resulting in insufficient long-term stability of the battery under high-temperature conditions.

[0359] The test results of Comparative Examples 1 and 3 show that the trimethyl borate coating layer cannot effectively improve the long-term stability of the battery under high-temperature conditions. This is because the steric hindrance effect of the methoxy groups in the molecular structure of trimethyl borate is large, and the mutual repulsion effect between the methoxy groups results in a low coverage of the coating layer on the core surface. The exposed core surface will be in direct contact with the electrolyte, thereby increasing the side reactions at the cathode-electrolyte interface. In addition, the amount of Mn dissolved during cycling is also relatively high.

[0360] As can be seen from the test results of Examples 2, 39 to 43, the performance of the battery can be further improved by further adjusting the coating weight content of the coating layer.

[0361] As can be seen from the test results of Examples 14 and 44 to 48, the performance of the battery can be further improved by further adjusting the coating weight content of the coating layer.

[0362] As can be seen from the test results of Examples 33, 49 to 53, the performance of the battery can be further improved by further adjusting the coating weight content of the coating layer.

[0363] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A composite cathode material, characterized in that, The composite cathode material includes a core and a coating layer located on at least a portion of the surface of the core; The core includes a positive electrode active material; The coating layer comprises one or more of boric acid, an organic compound having a -B-OH group, an organic compound having a -B-(OH)2 group, and their respective alkali metal salts, and the adsorption energy between the coating layer and the core is greater than the adsorption energy between the ethylene carbonate compound and the core.

2. The composite cathode material according to claim 1, characterized in that, The coating layer is a monolayer; and / or, The thickness of the coating layer is 0.2nm-3nm.

3. The composite cathode material according to any one of claims 1-2, characterized in that, The positive electrode active material includes one or more of the following: spinel-structured lithium manganese oxide, layered lithium-containing transition metal oxide, and lithium-containing phosphate.

4. The composite cathode material according to claim 3, characterized in that, The spinel-structured lithium manganese oxide includes one or more of LiMn2O4 and its doped materials.

5. The composite cathode material according to claim 3, characterized in that, The layered lithium-containing transition metal oxides include one or more of lithium nickel cobalt manganese oxides, lithium nickel cobalt aluminum oxides, and their respective doped materials.

6. The composite cathode material according to claim 3, characterized in that, The lithium-containing phosphate includes one or more of lithium iron phosphate, lithium manganese iron phosphate, and their respective doping materials.

7. The composite cathode material according to any one of claims 1-6, characterized in that, The coating layer comprises one or more of boric acid, organic compounds of formulas (1) to (3), and their respective alkali metal salts; Equation (1) Equation (2) Equation (3), R1, R2, and R3 independently comprise C1-C20 chain alkane groups, C1-C20 oxochain alkane groups, 3-8 membered cyclic alkane groups, 3-8 membered oxochain alkane groups, C2-C20 chain alkenyl groups, C2-C20 oxochain alkenyl groups, 3-8 membered cyclic alkenyl groups, C2-C20 chain alkyne groups, C2-C20 oxochain alkyne groups, 3-8 membered cyclic alkyne groups, 6-18 membered aromatic hydrocarbon groups, 6-18 membered aryloxy groups, 5-12 membered heteroaromatic hydrocarbon groups, and the aforementioned groups being modified by R. a One or more of the substituted groups; R4 includes single bonds, C1-C20 subchain alkane groups, C1-C20 oxoheterochain alkane groups, 3-8 membered subcyclic alkane groups, 3-8 membered oxoheterochain alkane groups, C2-C20 subchain olefin groups, C2-C20 oxoheterochain olefin groups, 3-8 membered subcyclic olefin groups, C2-C20 subchain alkyne groups, C2-C20 oxoheterochain alkyne groups, 3-8 membered subcyclic alkyne groups, 6-18 membered aromatic hydrocarbon groups, 5-12 membered heteroaromatic hydrocarbon groups, and the aforementioned groups being R a One or more of the substituted groups; R a It includes one or more combinations of halogen atoms, hydroxyl groups, amino groups, phenyl groups, cyclohexyl groups, C1-C6 chain alkane groups and their halogenated groups, C2-C6 chain olefin groups and their halogenated groups, C1-C6 oxochain alkane groups and their halogenated groups, and C2-C6 oxochain olefin groups and their halogenated groups.

8. The composite cathode material according to claim 7, characterized in that, R1, R2, and R3 independently comprise C1-C10 chain alkane groups, C1-C10 oxachain alkane groups, 3-8 membered cyclic alkane groups, 3-8 membered oxachain alkane groups, C2-C10 chain alkenyl groups, C2-C10 oxachain alkenyl groups, 3-8 membered cyclic alkenyl groups, C2-C10 chain alkyne groups, C2-C10 oxachain alkyne groups, 3-8 membered cyclic alkyne groups, 6-10 membered aromatic hydrocarbon groups, 6-10 membered aryloxy groups, 5-10 membered heteroaromatic hydrocarbon groups, and the aforementioned groups being modified by R. a One or more of the substituted groups, in combination.

9. The composite cathode material according to claim 7, characterized in that, R4 includes single bonds, C1-C10 subchain alkane groups, C1-C10 oxoheterochain alkane groups, 3-8 membered subcyclic alkane groups, 3-8 membered oxoheterochain alkane groups, C2-C10 subchain olefin groups, C2-C10 oxoheterochain olefin groups, 3-8 membered subcyclic olefin groups, C2-C10 subchain alkyne groups, C2-C10 oxoheterochain alkyne groups, 3-8 membered subcyclic alkyne groups, 6-10 membered aromatic hydrocarbon groups, 5-10 membered heteroaromatic hydrocarbon groups, and the aforementioned groups being R a One or more of the substituted groups, in combination.

10. The composite cathode material according to claim 7, characterized in that, R a It includes one or more combinations of fluorine atoms, chlorine atoms, bromine atoms, hydroxyl groups, amino groups, phenyl groups, cyclohexyl groups, C1-C4 chain alkane groups and their halogenated groups, C2-C4 chain olefin groups and their halogenated groups, C1-C4 oxochain alkane groups and their halogenated groups, and C2-C4 oxochain olefin groups and their halogenated groups.

11. The composite cathode material according to any one of claims 7-10, characterized in that, R1, R2, and R3 independently include C1-C10 chain alkane groups, C1-C10 oxochain alkane groups, 3-8 membered cyclic alkane groups, 3-8 membered oxocyclic alkane groups, and the aforementioned groups being replaced by R. a One or more of the substituted groups; And / or, R4 includes single bonds, C1-C10 subchain alkane groups, C1-C10 oxoheterochain alkane groups, 3-8 membered subcyclic alkane groups, 3-8 membered oxoheterocyclic alkane groups, and the aforementioned groups being R a One or more of the substituted groups; And / or, R a It includes one or more combinations of fluorine atoms, chlorine atoms, bromine atoms, hydroxyl groups, and amino groups.

12. The composite cathode material according to claim 11, characterized in that, R1, R2, and R3 independently include C1-C5 chain alkane groups, C1-C5 oxochain alkane groups, 3-5 membered cyclic alkane groups, and the aforementioned groups being replaced by R. a One or more of the substituted groups, in combination.

13. The composite cathode material according to claim 11, characterized in that, R4 includes a single bond, a C1-C5 subchain alkane group, and the aforementioned group being R a One or more of the substituted groups, in combination.

14. The composite cathode material according to any one of claims 11-13, characterized in that, The coating layer comprises one or more of the following organic compounds and their respective alkali metal salts: 。 15. The composite cathode material according to claim 14, characterized in that, The coating layer comprises one or more of the following organic compounds and their respective alkali metal salts: 。 16. The composite cathode material according to any one of claims 7-10, characterized in that, R1 includes C2-C10 chain olefinic groups, C2-C10 oxochain olefinic groups, C2-C10 chain alkyneic groups, C2-C10 oxochain alkyneic groups, and the aforementioned groups are covered by R. a One or more of the substituted groups; And / or, R2 and R3 independently comprise C1-C10 chain alkane groups, C1-C10 oxochain alkane groups, 3-8 membered cyclic alkane groups, 3-8 membered oxochain alkane groups, C2-C10 chain alkenyl groups, C2-C10 oxochain alkenyl groups, C2-C10 chain alkyne groups, C2-C10 oxochain alkyne groups, and the aforementioned groups being R a The substituted group is one or more combinations thereof, and at least one of R2 and R3 includes a C2-C10 chain olefin group, a C2-C10 oxochain olefin group, a C2-C10 chain alkyne group, a C2-C10 oxochain alkyne group, and the aforementioned group is replaced by R a One or more of the substituted groups; And / or, R4 includes C2-C10 subchain olefinic groups, C2-C10 oxyheterochain olefinic groups, C2-C10 subchain alkyneic groups, C2-C10 oxyheterochain alkyneic groups, and the aforementioned groups are coated with R. a One or more of the substituted groups; And / or, R a It includes one or more combinations of fluorine atoms, chlorine atoms, bromine atoms, hydroxyl groups, and amino groups.

17. The composite cathode material according to claim 16, characterized in that, R1 includes C2-C5 chain olefin groups, C2-C5 oxochain olefin groups, and the aforementioned groups are covered by R. a One or more of the substituted groups, in combination.

18. The composite cathode material according to claim 16, characterized in that, R2 and R3 each independently comprise a C1-C5 chain alkane group, a C1-C5 oxochain alkane group, a C2-C5 chain olefin group, a C2-C5 oxochain olefin group, a C2-C5 chain alkyne group, a C2-C5 oxochain alkyne group, and the aforementioned groups being modified by R. a The substituted group is one or more of the following combinations, and at least one of R2 and R3 includes a C2-C5 chain olefin group, a C2-C5 oxochain olefin group, and the aforementioned group is replaced by R. a One or more of the substituted groups, in combination.

19. The composite cathode material according to claim 16, characterized in that, R4 includes C2-C5 subchain olefin groups, C2-C5 oxyheterochain olefin groups, and the aforementioned groups are covered by R. a One or more of the substituted groups, in combination.

20. The composite cathode material according to any one of claims 16-19, characterized in that, The coating layer comprises one or more of the following organic compounds and their respective alkali metal salts: 。 21. The composite cathode material according to claim 20, characterized in that, The coating layer comprises one or more of the following organic compounds and their respective alkali metal salts: 。 22. The composite cathode material according to any one of claims 7-10, characterized in that, R1 includes 3-8 membered cyclic alkenyl groups, 3-8 membered cyclic alkyne groups, 6-10 membered aromatic hydrocarbon groups, 6-10 membered aryloxy groups, 5-10 membered heteroaromatic hydrocarbon groups, and the aforementioned groups are marked with R. a One or more of the substituted groups; And / or, R2 and R3 independently comprise C1-C10 chain alkane groups, C1-C10 oxochain alkane groups, 3-8 membered cyclic alkane groups, 3-8 membered oxochain alkane groups, C2-C10 chain alkenyl groups, C2-C10 oxochain alkenyl groups, 3-8 membered cyclic alkenyl groups, C2-C10 chain alkyne groups, C2-C10 oxochain alkyne groups, 3-8 membered cyclic alkyne groups, 6-10 membered aromatic hydrocarbon groups, 6-10 membered aryloxy groups, 5-10 membered heteroaromatic hydrocarbon groups, and the aforementioned groups being converted by R. a The substituted groups are one or more combinations thereof, and at least one of R2 and R3 includes a 3-8 membered cyclic olefinic group, a 3-8 membered cyclic alkynyl group, a 6-10 membered aromatic hydrocarbon group, a 6-10 membered aryloxy group, a 5-10 membered heteroaromatic hydrocarbon group, and the aforementioned groups are replaced by R. a One or more of the substituted groups; And / or, R4 includes 3-8 membered subcyclic olefinic groups, 3-8 membered subcyclic alkyneic groups, 6-10 membered aromatic hydrocarbonic groups, 5-10 membered heteroaromatic hydrocarbonic groups, and the aforementioned groups are marked with R. a One or more of the substituted groups, in combination.

23. The composite cathode material according to claim 22, characterized in that, R1 includes 5-6 membered cyclic alkenyl groups, phenyl groups, phenoxy groups, pyridyl groups, pyrimidinyl groups, benzodioxane groups, benzothiophene groups, triphenylamine groups, and the aforementioned groups are marked with R. a One or more of the substituted groups, in combination.

24. The composite cathode material according to claim 22, characterized in that, R2 and R3 independently comprise C1-C5 chain alkane groups, C1-C5 oxochain alkane groups, C2-C5 chain alkenyl groups, C2-C5 oxochain alkenyl groups, 3-6 membered cyclic alkenyl groups, C2-C5 chain alkyne groups, C2-C5 oxochain alkyne groups, 3-6 membered cyclic alkyne groups, 6-10 membered aromatic hydrocarbon groups, 6-10 membered aryloxy groups, 5-10 membered heteroaromatic hydrocarbon groups, and the aforementioned groups being replaced by R. a A combination of one or more of the substituted groups, and at least one of R2 and R3 includes a phenyl group and the aforementioned group is replaced by R. a One or more of the substituted groups, in combination.

25. The composite cathode material according to claim 22, characterized in that, R4 includes phenyl, biphenyl, and the aforementioned groups being R a One or more of the substituted groups, in combination.

26. The composite cathode material according to any one of claims 22-25, characterized in that, The coating layer comprises one or more of the following organic compounds and their respective alkali metal salts: 。 27. The composite cathode material according to claim 26, characterized in that, The coating layer comprises one or more of the following organic compounds and their respective alkali metal salts: 。 28. The composite cathode material according to any one of claims 7-10, characterized in that, The coating layer includes a first coating layer material and a second coating layer material; The first coating material comprises boric acid, organic compounds of formulas (1) to (3), and one or more of their respective alkali metal salts, and R1, R2, and R3 independently comprise C1-C10 chain alkane groups, C1-C10 oxochain alkane groups, 3-8 membered cyclic alkane groups, 3-8 membered oxocyclic alkane groups, and the aforementioned groups are coated with R a The substituted groups include one or more combinations thereof; R4 includes single bonds, C1-C10 subchain alkane groups, C1-C10 oxoheterochain alkane groups, 3-8 membered subcyclic alkane groups, 3-8 membered oxoheterocyclic alkane groups, and the aforementioned groups being replaced by R. a One or more of the substituted groups; The second coating material comprises one or more of the organic compounds of formulas (1) to (3) and their respective alkali metal salts, and R1 comprises C2-C10 chain olefins, C2-C10 oxochain olefins, C2-C10 chain alkynes, C2-C10 oxochain alkynes, 3-8 membered cyclic olefins, 3-8 membered cyclic alkynes, 6-10 membered aromatic hydrocarbons, 6-10 membered aryloxy groups, 5-10 membered heteroaromatic hydrocarbons, and the aforementioned groups are coated with R. a The substituted groups include one or more combinations thereof; R2 and R3 independently comprise C1-C10 chain alkane groups, C1-C10 oxachain alkane groups, 3-8 membered cyclic alkane groups, 3-8 membered oxachain alkane groups, C2-C10 chain alkenyl groups, C2-C10 oxachain alkenyl groups, 3-8 membered cyclic alkenyl groups, C2-C10 chain alkyne groups, C2-C10 oxachain alkyne groups, 3-8 membered cyclic alkyne groups, 6-10 membered aromatic hydrocarbon groups, 6-10 membered aryloxy groups, 5-10 membered heteroaromatic hydrocarbon groups, and the aforementioned groups being replaced by R a The substituted group is one or more combinations thereof, and at least one of R2 and R3 includes a C2-C10 chain olefin group, a C2-C10 oxochain olefin group, a C2-C10 chain alkyne group, a C2-C10 oxochain alkyne group, a 3-8 membered cyclic olefin group, a 3-8 membered cyclic alkyne group, a 6-10 membered aromatic hydrocarbon group, a 6-10 membered aryloxy group, a 5-10 membered heteroaromatic hydrocarbon group, and the aforementioned group is replaced by R a The substituted group is one or more combinations thereof; R4 includes C2-C10 subchain olefinic groups, C2-C10 oxoheterochain olefinic groups, C2-C10 subchain alkynyl groups, C2-C10 oxoheterochain alkynyl groups, 3-8 membered subcyclic olefinic groups, 3-8 membered subcyclic alkynyl groups, 6-10 membered aromatic hydrocarbon groups, 5-10 membered heteroaromatic hydrocarbon groups, and the aforementioned groups being replaced by R. a One or more of the substituted groups, in combination.

29. The composite cathode material according to claim 28, characterized in that, In the first coating layer material, R1, R2, and R3 independently include C1-C5 chain alkane groups, C1-C5 oxochain alkane groups, 3-5 membered cyclic alkane groups, and the aforementioned groups are covered by R. a One or more of the substituted groups, in combination.

30. The composite cathode material according to claim 28, characterized in that, In the first coating layer material, R4 includes single bonds, C1-C5 subchain alkane groups, and the aforementioned groups are coated with R. a One or more of the substituted groups; R a It includes one or more combinations of fluorine atoms, chlorine atoms, bromine atoms, hydroxyl groups, and amino groups.

31. The composite cathode material according to claim 28, characterized in that, The first coating material includes one or more of the following organic compounds and their respective alkali metal salts: 。 32. The composite cathode material according to claim 31, characterized in that, The first coating material includes one or more of the following organic compounds and their respective alkali metal salts: 。 33. The composite cathode material according to claim 28, characterized in that, In the second coating material, R1 includes C2-C5 chain olefins, C2-C5 oxochain olefins, 5-6 membered cyclic olefins, phenyl, phenoxy, pyridyl, pyrimidinyl, benzodioxane, benzothiophene, triphenylamine, and the aforementioned groups are coated with R. a One or more of the substituted groups, in combination.

34. The composite cathode material according to claim 28, characterized in that, In the second coating material, R2 and R3 independently comprise C1-C5 chain alkane groups, C1-C5 oxochain alkane groups, C2-C5 chain olefin groups, C2-C5 oxochain olefin groups, 3-6 membered cyclic olefin groups, C2-C5 chain alkyne groups, C2-C5 oxochain alkyne groups, 3-6 membered cyclic alkyne groups, 6-10 membered aromatic hydrocarbon groups, 6-10 membered aryloxy groups, 5-10 membered heteroaromatic hydrocarbon groups, and the aforementioned groups are covered by R. a The substituted group is one or more of the following combinations, and at least one of R2 and R3 includes a C2-C5 chain olefin group, a C2-C5 oxochain olefin group, a phenyl group, and the aforementioned group is replaced by R. a One or more of the substituted groups, in combination.

35. The composite cathode material according to claim 28, characterized in that, In the second coating material, R4 includes C2-C5 subchain olefin groups, C2-C5 oxyheterochain olefin groups, phenyl groups, biphenyl groups, and the aforementioned groups coated with R. a One or more of the substituted groups; R a It includes one or more combinations of fluorine atoms, chlorine atoms, bromine atoms, hydroxyl groups, and amino groups.

36. The composite cathode material according to claim 28, characterized in that, The second coating material comprises one or more of the following organic compounds and their respective alkali metal salts: 。 37. The composite cathode material according to claim 36, characterized in that, The second coating material comprises one or more of the following organic compounds and their respective alkali metal salts: 。 38. The composite cathode material according to any one of claims 7-10, characterized in that, The coating layer comprises one or more of the organic compounds shown in formula (3) and their alkali metal salts.

39. The composite cathode material according to claim 38, characterized in that, The coating layer comprises one or more of the following organic compounds and their respective alkali metal salts: 。 40. The composite cathode material according to any one of claims 1-39, characterized in that, The coating layer has a weight content of 0.01%-1%, based on the total weight of the composite cathode material.

41. The composite cathode material according to claim 40, characterized in that, The coating layer has a weight content of 0.1%-0.5%, based on the total weight of the composite cathode material.

42. The composite cathode material according to any one of claims 1-41, characterized in that, The coating layer covers 80%-100% of the surface of the core.

43. A method for preparing the composite cathode material according to any one of claims 1-42, characterized in that, Includes the following steps: A core material is provided, wherein the core material includes a positive electrode active material; A coating material is provided, wherein the coating material comprises one or more of boric acid, an organic compound having a -B-OH group, an organic compound having a -B-(OH)2 group, and their respective alkali metal salts; The core material and the coating material are stirred and mixed evenly in the presence of a solvent, and then dried to obtain a composite cathode material. The composite cathode material includes a core and a coating layer located on at least a portion of the surface of the core, wherein the adsorption energy between the coating layer and the core is greater than the adsorption energy between the ethylene carbonate compound and the core.

44. The method according to claim 43, characterized in that, In the step of mixing the core material and the coating material evenly in the presence of a solvent, and then drying to obtain the composite cathode material... The mixing temperature is 0℃-100℃; The mixing time is 0.5h-12h; The solvent includes one or more of water, alcohol, ether, ester, and ketone; The drying temperature is 40℃-80℃; and / or, The drying time is 4h-24h.

45. The method according to claim 44, characterized in that, The mixing temperature is 50℃-80℃; and / or, The mixing time is 1-6 hours; and / or, The drying temperature is 50℃-60℃; and / or, The drying time is 6-12 hours.

46. ​​A positive electrode sheet, comprising a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector, characterized in that, The positive electrode film layer includes the composite positive electrode material according to any one of claims 1-42 or the composite positive electrode material prepared by the method according to any one of claims 43-45.

47. The positive electrode sheet according to claim 46, characterized in that, The weight content of the composite cathode material in the cathode film is 50%-99%, based on the total weight of the cathode film.

48. The positive electrode sheet according to claim 47, characterized in that, The composite cathode material in the cathode film layer has a weight content of 80%-99%, based on the total weight of the cathode film layer.

49. A battery, characterized in that, Includes the positive electrode sheet as described in any one of claims 46-48.

50. An electrical device, characterized in that, Includes the battery of claim 49, the battery being used to provide electrical energy.

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