Positive pole piece and preparation method thereof, battery monomer, battery and electric device

Abstract

The embodiment of the invention provides a positive pole piece, a preparation method of the positive pole piece, a battery monomer, a battery and a power utilization device. The positive pole piece comprises a positive current collector and a coating, the coating is arranged on the surface of at least one side of the positive current collector, the coating comprises a positive active material and an additive, and the additive comprises metal carbide. According to the technical scheme, the cycle performance and the storage stability of the battery can be improved.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a positive electrode plate and a preparation method thereof, a battery cell, a battery and an electrical device. Background Art

[0002] In recent years, the application scope of secondary batteries has become increasingly wide. They are widely used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields.

[0003] With the great development and wide application of secondary batteries, higher requirements have been put forward for their cycle performance, storage performance and other properties. Therefore, how to improve the cycle performance and storage performance of secondary batteries is a technical problem that needs to be solved urgently. Summary of the invention

[0004] The embodiments of the present application provide a positive electrode plate and a preparation method thereof, a battery cell, a battery and an electrical device. The battery containing the positive electrode plate has improved cycle performance and storage stability.

[0005] In a first aspect, a positive electrode plate is provided, comprising: a positive electrode current collector; a coating, wherein the coating is disposed on a surface of at least one side of the positive electrode current collector, the coating comprising a positive electrode active material and an additive, wherein the additive comprises a metal carbide.

[0006] The present application provides a positive electrode sheet, including a positive electrode current collector and a coating. Specifically, the coating is disposed on the surface of at least one side of the positive electrode current collector, and the coating includes a positive electrode active material and an additive, and the additive includes a metal carbide. The metal carbide can react with water. When the coating of the positive electrode sheet includes a metal carbide, the metal carbide used as an additive can react with trace moisture in the battery and consume the moisture in the battery, thereby improving the reaction of the trace moisture in the battery with the electrolyte components to produce acidic substances (such as HF, organic acid RH). + , H· free radicals, etc.), thereby improving the situation of acidic substances decomposing the interface film, so as to improve the cycle performance and storage stability of the battery. At the same time, metal carbides are inorganic compounds with a small molecular weight. When added to the coating of the positive electrode plate, the increase in the overall mass of the positive electrode plate is small; and when the additives in the embodiments of the present application react chemically with water, a small amount of metal carbides can consume more water, achieving a better dehydration effect, and better improving the cycle performance and storage stability of the battery.

[0007] In a possible implementation, the additive includes at least one of calcium carbide, magnesium carbide, and aluminum carbide.

[0008] Calcium carbide, magnesium carbide and aluminum carbide can all react with water, and a small amount of calcium carbide, magnesium carbide and aluminum carbide can consume a large amount of water, achieving a better water removal effect and better improving the battery's cycle performance and storage stability.

[0009] In a possible implementation, based on the total mass of the coating, the mass content of the additive in the coating ranges from 0.05% to 0.5%.

[0010] If the mass content of the additive in the coating is too low, the additive content is insufficient and only a small amount of water in the battery can be consumed; if the mass content of the additive in the coating is too high, the excess additive leads to material waste and increases the battery mass. Therefore, setting the mass content of the additive in the coating within the above range is conducive to improving the performance of the battery.

[0011] In a possible implementation, the positive electrode active material includes at least one of an olivine structure phosphate material, a spinel material, and a layered transition metal oxide.

[0012] Olivine structure is a crystal structure of materials. Materials with olivine structure have high stability. When applied to battery cells, they can reduce the risk of fire and explosion of battery cells under high temperature and other conditions, which is beneficial to improve the reliability of battery cells. Olivine structure phosphate has the advantages of high theoretical specific capacity, good cycle stability, low cost and environmental friendliness. Spinel is a mineral composed of magnesium aluminum oxide, with tetrahedral and octahedral crystal forms. For example, spinel-type lithium manganese oxide materials have outstanding characteristics such as high specific capacity, low cost and low environmental pollution. Layered transition metal oxides as positive electrode active materials of batteries are a class of oxides with multilayer (generally two-dimensional) structures, which are obtained based on the redox reaction of transition metal cations and lattice oxygen anions, and have high energy and high power density. Layered transition metal oxides can be used as the second active material to increase the energy density of the battery. Olivine structure phosphate materials, spinel materials, and layered transition metal oxides are used as positive electrode active materials, which are beneficial to improve the performance of the battery.

[0013] In a possible implementation, the olivine structure phosphate material includes Li a Fe b M 1-b P 1-m O 4-n, wherein M includes at least one of the other metal elements except Fe, wherein 0≤a≤1.1, 0.3≤b≤1, 0≤m≤0.1, 0≤n≤0.1, optionally, M includes at least one of Mn, Al, Cu, Mg, Zn, Ni, Ti, V, Zr, Co, Ga, Sn, Sb, Nb and Ge, optionally, the olivine structure phosphate material includes at least one of lithium iron phosphate (LiFePO4) and lithium manganese iron phosphate (LiMnFePO4).

[0014] Lithium iron phosphate has the advantages of long cycle life, good thermal stability, and high energy density; lithium iron manganese phosphate also has the advantages of long cycle life and good thermal stability. Lithium iron phosphate and lithium iron manganese phosphate are used as positive electrode active materials to improve the cycle performance, energy density and safety of batteries.

[0015] In a possible implementation, the spinel material includes LiNi c Mn 2-c O4, wherein 0≤c<2, optionally, the spinel material comprises lithium manganate.

[0016] Lithium manganese oxide used as positive electrode active material has the advantages of low price, high potential, environmental friendliness, high safety performance and good rate performance.

[0017] In a possible implementation, the layered transition metal oxide includes LiCoO2, LiMnO2, LiNiO2, Li a’ Ni x Co y M 1 1-x-y O 2+d 、zLi2MnO3·(1-z)LiM 2 O2 at least one, wherein M 1 Including at least one of Mn, Zr, Al, B, Ta, Mo, W, Nb, Sb, La, M 2 It includes at least one of Co, Ni, and Mn, 0.5≤x≤1.0, 0≤y<0.5, x+y<1, 0.2≤a'<1.2, -0.02≤d<0.02, 0<z<1, and optionally, the layered transition metal oxide includes lithium nickel cobalt manganese oxide.

[0018] Lithium nickel cobalt manganese oxide used as positive electrode active material has the advantages of high energy density, high voltage platform, good thermal stability and good cycle performance.

[0019] In a possible implementation, based on the total mass of the coating, the mass content of the positive electrode active material in the coating ranges from 93% to 99%.

[0020] Setting the mass content of the positive electrode active material in the coating within the above range is beneficial to improving the performance of the battery.

[0021] In a possible implementation, the coating further includes a conductive agent, and the conductive agent includes at least one of conductive carbon black, superconducting carbon, carbon dots, carbon nanotubes, graphene, and Ketjen black.

[0022] Conductive agents collect microcurrents between active materials to reduce the contact resistance of the electrode and accelerate the movement rate of electrons. They can also effectively increase the migration rate of metal ions in the electrode material, thereby improving the charge and discharge efficiency of the electrode. Due to the unique composition of the carbon structure, carbon material conductive agents have good conductivity. For example, conductive carbon black has low resistance and high conductivity, small particle size, large and rough specific surface area, high structure, clean surface (few compounds), etc. Ketjen black has a unique branched morphology, so it has high conductivity; carbon atoms in carbon nanotubes adopt SP 2 Hybridization, thus having high modulus and high strength, carbon nanotubes also have good flexibility, stretchability and conductivity. Conductive carbon black, superconducting carbon, carbon dots, carbon nanotubes, graphene and Ketjen black as conductive agents can improve the conductivity of batteries.

[0023] In a possible implementation, the coating further includes a binder, and the binder includes at least one of polyvinylidene fluoride, polyacrylonitrile, polyacrylate, polyacrylic acid, and acrylonitrile-acrylate-acrylic acid copolymer.

[0024] The binder can make the active material and the conductive agent bond, enhance the electrical contact between the active material and the conductive agent, and stabilize the structure of the positive electrode. The above substances all have good bonding properties, and can be used as binders to enhance the bonding force between the active material and the conductive agent and the structural stability of the positive electrode.

[0025] In a possible implementation, based on the total mass of the coating, the mass content of the binder in the coating ranges from 1% to 5%.

[0026] Setting the mass content of the binder in the coating within the above range is beneficial to improving the performance of the battery.

[0027] In a possible implementation, the positive electrode plate is used in a lithium-ion battery, which can improve the cycle performance and storage stability of the lithium-ion battery.

[0028] In a second aspect, a method for preparing a positive electrode plate is provided, comprising: providing a positive electrode current collector, and arranging a coating on the positive electrode current collector; wherein the coating is arranged on the surface of at least one side of the positive electrode current collector, the coating comprises a positive electrode active material and an additive, and the additive comprises a metal carbide.

[0029] In a third aspect, a battery cell is provided, comprising the positive electrode plate in the first aspect and any possible implementation thereof.

[0030] In a fourth aspect, a battery is provided, comprising the battery cell described in the third aspect.

[0031] In a fifth aspect, an electrical device is provided, comprising the battery described in the fourth aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without paying creative work.

[0033] Figure 1 A schematic diagram of a positive electrode sheet according to an embodiment of the present application;

[0034] Figure 2 A schematic diagram of a positive electrode sheet according to an embodiment of the present application;

[0035] Figure 3 is a schematic diagram of a battery cell disclosed in an embodiment of the present application;

[0036] Figure 4 is a schematic diagram of the exploded structure of a battery cell disclosed in one embodiment of the present application;

[0037] Figure 5 is a schematic diagram of the exploded structure of a battery disclosed in one embodiment of the present application;

[0038] Figure 6 It is a schematic diagram of an electrical device disclosed in one embodiment of the present application.

[0039] In the drawings, the drawings are not drawn to scale.

[0040] The reference numerals in the specific implementation manner are as follows:

[0041] Positive electrode sheet 1, positive electrode current collector 10, coating 11, battery cell 20, shell 21, electrode assembly 22, cover plate 23, battery 30, box 31. DETAILED DESCRIPTION

[0042] Hereinafter, the embodiments of the positive electrode plate and its preparation method, battery cell, battery and electrical device of the present application are specifically disclosed in detail with appropriate reference to the drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structure are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following descriptions are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0043] In the description of this application, it should be noted that, unless otherwise specified, "multiple" means more than two; the terms "upper", "lower", "left", "right", "inner", "outer", etc., indicating directions or positional relationships, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting this application. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0044] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0045] If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0046] If there is no special explanation, the "include" and "comprising" mentioned in this application represent open-ended. For example, the "include" and "comprising" may mean including or comprising other components not listed.

[0047] If not specifically stated, in this application, the term "and / or" is inclusive. For example, the phrase "A and / or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A and / or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0048] If not otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0049] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0050] A secondary battery is a battery that can be used again after being discharged by recharging the active materials. Usually, a secondary battery includes a positive electrode, a negative electrode, a separator and an electrolyte. During the battery charging and discharging process, active ions are embedded and released back and forth between the positive electrode and the negative electrode. The separator is set between the positive electrode and the negative electrode to play an isolating role. The electrolyte plays the role of conducting ions between the positive electrode and the negative electrode.

[0051] Secondary batteries may include lithium-ion batteries, sodium-ion batteries, magnesium-ion batteries, etc. This application takes lithium-ion batteries as an example. Lithium-ion batteries are a typical type of secondary batteries. Since they rely on the chemical reaction of lithium ions being embedded and released between the positive and negative electrodes for charging and discharging, lithium-ion batteries are also called rocking-chair batteries. During the charging process of lithium-ion batteries, lithium ions are released from the positive electrode, moved and embedded in the negative electrode; and during the discharging process, lithium ions are released from the negative electrode, moved and embedded in the positive electrode.

[0052] In recent years, secondary batteries have been greatly developed and widely used in power tools, electronic products, electric vehicles, aerospace and other fields. At the same time, higher requirements are also placed on the volume capacity, energy density, cycle performance and storage stability of secondary batteries.

[0053] During the first charge of a secondary battery, the film-forming additives in the electrolyte will be reduced to form a solid electrolyte interphase (SEI) film on the surface of the electrode. The SEI film can prevent the non-aqueous organic solvent in the electrolyte from further decomposing and form ion channels in the subsequent charge and discharge cycles. However, trace amounts of water in the battery will react with the electrolyte components to generate acidic substances (such as HF, organic acid RH + , H· free radicals, etc.), causing the electrolyte to be continuously consumed, and the acidic substances will corrode and decompose the SEI film, eventually leading to the deterioration of the battery's cycle performance and storage performance.

[0054] In view of this, the embodiment of the present application provides a positive electrode plate, including a positive electrode current collector and a coating disposed on the surface of at least one side of the positive electrode current collector, the coating including a positive electrode active material and an additive, and the additive including a metal carbide. Metal carbide can react with water. When the coating of the positive electrode plate includes metal carbide, the metal carbide used as an additive can react with trace moisture in the battery and consume the moisture in the battery, thereby improving the problem of trace moisture in the battery reacting with electrolyte components to produce acidic substances, thereby improving the situation of acidic substances decomposing the interface film, so as to improve the battery's cycle performance and storage stability. At the same time, metal carbide is an inorganic compound with a small molecular weight. When added to the coating of the positive electrode plate, the increase in the overall mass of the positive electrode plate is small; and when the additive in the embodiment of the present application reacts chemically with water, a small amount of metal carbide can consume more water, achieving a better dehydration effect, and better improving the battery's cycle performance and storage stability.

[0055] Several embodiments of the present application are described in detail below.

[0056] [Positive electrode]

[0057] Figure 1 Schematic diagram of a positive electrode sheet according to an embodiment of the present application. Figure 1 As shown, the positive electrode sheet 1 includes a positive electrode current collector 10 and a coating 11 .

[0058] The coating 11 is disposed on the surface of the positive electrode current collector 10, for example, Figure 1 As shown, along the thickness direction of the positive electrode sheet 1 ( Figure 1 In the z direction), the positive electrode current collector 10 and the coating 11 are arranged in sequence.

[0059] The positive electrode current collector 10 has two surfaces arranged along its thickness direction. Figure 1 As shown, both surfaces of the positive electrode current collector 10 are provided with a coating layer 11 .

[0060] Figure 2 Schematic diagram of a positive electrode sheet of an embodiment of the present application. In some other embodiments, such as Figure 2 As shown, a coating layer 11 is provided on one of two surfaces of the positive electrode current collector 10 that are opposite to each other in the thickness direction.

[0061] The coating layer 11 includes a positive electrode active material and an additive, and the additive includes a metal carbide.

[0062] Metal carbides refer to binary compounds formed by carbon and an element with a smaller or similar electronegativity (except hydrogen). Carbides have a high melting point, and most carbides are obtained by the reaction of carbon and metal at high temperatures. For example, magnesium carbide, calcium carbide, etc.

[0063] In the embodiment of the present application, the positive electrode plate 1 includes a positive electrode current collector 10 and a coating 11. Specifically, the coating 11 is disposed on the surface of at least one side of the positive electrode current collector 10, and the coating 11 includes a positive electrode active material and an additive, and the additive includes a metal carbide. The metal carbide can react with water. When the coating 11 of the positive electrode plate 1 includes a metal carbide, the metal carbide used as an additive can react with trace moisture in the battery and consume the moisture in the battery, thereby improving the reaction of trace moisture in the battery with electrolyte components to produce acidic substances (such as HF, organic acid RH). + , H· free radicals, etc.), thereby improving the situation of acidic substances decomposing the interface film, so as to improve the cycle performance and storage stability of the battery. At the same time, the metal carbide is an inorganic compound with a small molecular weight. When added to the coating 11 of the positive electrode plate 1, the increase in the overall mass of the positive electrode plate 1 is small; and when the additive in the embodiment of the present application reacts chemically with water, a small amount of metal carbide can consume a large amount of water, achieving a better dehydration effect, and better improving the cycle performance and storage stability of the battery.

[0064] In some embodiments, the additive may include at least one of calcium carbide, magnesium carbide, and aluminum carbide.

[0065] Calcium carbide, magnesium carbide and aluminum carbide can all react with water, and a small amount of calcium carbide, magnesium carbide and aluminum carbide can consume a lot of water, achieving a better dehydration effect and better improving the battery's cycle performance and storage stability. For example, magnesium carbide reacts with water to generate magnesium hydroxide and propyne, and the molar ratio of magnesium carbide and water participating in the chemical reaction is 1:4, that is, 1 mole of magnesium carbide can consume 4 moles of water.

[0066] In some embodiments, based on the total mass of the coating 11 , the mass content of the additive in the coating 11 ranges from 0.05% to 0.5%.

[0067] Specifically, the mass content of the additive in the coating 11 may be 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, or a value between any two of the above values.

[0068] If the mass content of the additive in the coating 11 is too low, the additive content is insufficient and only a small amount of water in the battery can be consumed; if the mass content of the additive in the coating 11 is too high, the excess additive leads to material waste and increases the battery mass. Therefore, setting the mass content of the additive in the coating 11 within the above range is conducive to improving the performance of the battery.

[0069] In some embodiments, the positive electrode active material includes at least one of an olivine structure phosphate material, a spinel material, and a layered transition metal oxide.

[0070] Olivine structure is a crystal structure of materials. Materials with olivine structure have high stability. When applied to battery cells, they can reduce the risk of fire and explosion of battery cells under high temperature and other conditions, which is beneficial to improve the reliability of battery cells. Olivine structure phosphate has the advantages of high theoretical specific capacity, good cycle stability, low cost and environmental friendliness. Spinel is a mineral composed of magnesium aluminum oxide, with tetrahedral and octahedral crystal forms. For example, spinel-type lithium manganese oxide materials have outstanding characteristics such as high specific capacity, low cost and low environmental pollution. Layered transition metal oxides as positive electrode active materials of batteries are a class of oxides with multilayer (generally two-dimensional) structures, which are obtained based on the redox reaction of transition metal cations and lattice oxygen anions, and have high energy and high power density. Layered transition metal oxides can be used as the second active material to increase the energy density of the battery. Olivine structure phosphate materials, spinel materials, and layered transition metal oxides are used as positive electrode active materials, which are beneficial to improve the performance of the battery.

[0071] Optionally, in some embodiments, the olivine structure phosphate material includes Li a Fe b M 1-b P 1-m O 4-n , wherein M includes at least one of the other metal elements except Fe, wherein 0≤a≤1.1, 0.3≤b≤1, 0≤m≤0.1, 0≤n≤0.1, and optionally, M includes at least one of Mn, Al, Cu, Mg, Zn, Ni, Ti, V, Zr, Co, Ga, Sn, Sb, Nb and Ge.

[0072] Optionally, the olivine structure phosphate material includes at least one of LiFePO4 and LiMnFePO4.

[0073] LiFePO4 has the advantages of long cycle life, good thermal stability, and high energy density; LiMnFePO4 also has the advantages of long cycle life and good thermal stability. Lithium iron phosphate and lithium manganese iron phosphate are used as positive electrode active materials to improve the cycle performance, energy density and safety of batteries.

[0074] Optionally, in some embodiments, the spinel material includes LiNi c Mn 2-c O4, where 0≤c<2.

[0075] Optionally, the spinel material includes lithium manganate. Lithium manganate used as a positive electrode active material has the advantages of low price, high potential, environmental friendliness, high safety performance, and good rate performance.

[0076] Optionally, in some embodiments, the layered transition metal oxide includes LiCoO2, LiMnO2, LiNiO2, Li a’ Ni x Co y M 1 1-x-y O 2+d 、zLi2MnO3·(1-z)LiM 2 O2, wherein M 1 Including at least one of Mn, Zr, Al, B, Ta, Mo, W, Nb, Sb, La, M 2 The invention comprises at least one of Co, Ni and Mn, 0.5≤x≤1.0, 0≤y<0.5, x+y<1, 0.2≤a'<1.2, -0.02≤d<0.02, 0<z<1.

[0077] Optionally, the layered transition metal oxide includes lithium nickel cobalt manganese oxide, such as Li(Ni 0.6 Co 0.2 Mn 0.2 ) 1.15 O2, for example, Li(Ni 0.5 Co 0.2 Mn 0.3 ) 1.07 O2.

[0078] Lithium nickel cobalt manganese oxide used as positive electrode active material has the advantages of high energy density, high voltage platform, good thermal stability and good cycle performance.

[0079] It should be understood that the above-mentioned LiFePO4, LiMnFePO4, lithium manganese oxide, and lithium nickel cobalt manganese oxide are only exemplary illustrations of the substances used as positive electrode active materials in the embodiments of the present application. The positive electrode active materials may include the above-mentioned substances, but are not limited to the above-mentioned substances. For example, the positive electrode active materials may also include lithium nickel phosphate, lithium cobalt phosphate, etc.

[0080] In addition, the battery will be accompanied by Li deintercalation and consumption during the charge and discharge process, and the molar content of Li is different when the battery is discharged to different states. In the list of positive electrode active materials in this application, the molar content of Li is the initial state of the material, that is, the state before feeding. The positive electrode active material is used in the battery system, and the molar content of Li will change after charge and discharge cycles.

[0081] In the list of positive electrode active materials in this application, the molar content of O is only a theoretical value. The release of oxygen from the lattice will cause the molar content of oxygen to change, and the actual molar content of O will fluctuate.

[0082] It should be understood that the value of the mass content of the additive in the coating 11 is related to the type of the positive electrode active material in the coating 11 (that is, it is related to the type of the battery system). For example, when the positive electrode active material in the coating 11 is an olivine structure phosphate material, the olivine structure phosphate material absorbs relatively more water, so the mass content of the additive in the coating 11 is relatively high, which can be 0.3% to 0.5%; for another example, when the positive electrode active material in the coating 11 is a spinel material or a layered transition metal oxide, the spinel material and the layered transition metal oxide absorb relatively less water, so the mass content of the additive in the coating 11 is relatively low, which can be 0.05% to 0.15%.

[0083] In some embodiments, based on the total mass of the coating 11 , the mass content of the positive electrode active material in the coating 11 ranges from 93% to 99%.

[0084] Specifically, the mass content of the positive electrode active material in the coating layer 11 can be 93%, 94%, 95%, 95.5%, 96%, 97%, 98%, 99%, or a value between any two of the above values.

[0085] The mass content of the positive electrode active material in the coating layer 11 is set within the above range, which is beneficial to improving the performance of the battery.

[0086] In some embodiments, the coating 11 may further include a conductive agent.

[0087] Optionally, the conductive agent includes at least one of conductive carbon black, superconducting carbon, carbon dots, carbon nanotubes, graphene, and Ketjen black.

[0088] Conductive agents collect microcurrents between active materials to reduce the contact resistance of the electrode and accelerate the movement rate of electrons. They can also effectively increase the migration rate of metal ions in the electrode material, thereby improving the charge and discharge efficiency of the electrode. Due to the unique composition of the carbon structure, carbon material conductive agents have good conductivity. For example, conductive carbon black has the advantages of low resistance and high conductivity, small particle size, large and rough specific surface area, high structure, and clean surface (few compounds); Ketjen black has a unique branched morphology and thus has high conductivity; carbon atoms in carbon nanotubes adopt SP2 hybridization, so they have high modulus and high strength. Carbon nanotubes also have good flexibility, stretchability and conductivity. Conductive carbon black, superconducting carbon, carbon dots, carbon nanotubes, graphene and Ketjen black can be used as conductive agents to improve the conductivity of batteries.

[0089] In some embodiments, the coating 11 may further include a binder.

[0090] Optionally, the binder includes at least one of polyvinylidene fluoride, polyacrylonitrile, polyacrylate, polyacrylic acid, and acrylonitrile-acrylate-acrylic acid copolymer.

[0091] The binder can bond the active material to the conductive agent, enhance the electrical contact between the active material and the conductive agent, and stabilize the structure of the positive electrode sheet 1. The above substances all have good bonding properties, and can be used as a binder to enhance the bonding force between the active material and the conductive agent and the structural stability of the positive electrode sheet 1.

[0092] In some embodiments, based on the total mass of the coating 11 , the mass content of the binder in the coating 11 ranges from 1% to 5%.

[0093] Specifically, the mass content of the binder in the coating 11 may be 1%, 2%, 2.5%, 3%, 4%, 4.5%, 5%, or a value between any two of the above values.

[0094] The mass content of the binder in the coating layer 11 is set within the above range, which is beneficial to improving the performance of the battery.

[0095] In some embodiments, the positive electrode plate 1 can be used in lithium-ion batteries to improve the cycle performance and storage stability of lithium-ion batteries.

[0096] [Method for preparing positive electrode sheet]

[0097] The method for preparing a positive electrode plate comprises: providing a positive electrode current collector, and arranging a coating on the positive electrode current collector.

[0098] The coating is disposed on the surface of at least one side of the positive electrode current collector, and the coating includes a positive electrode active material and an additive, and the additive includes a metal carbide.

[0099] The positive electrode sheet prepared by the above preparation method is used in batteries to improve the cycle performance and storage stability of the batteries.

[0100] [Negative electrode]

[0101] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material.

[0102] As an example, the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.

[0103] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, copper foil may be used. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0104] In some embodiments, the negative electrode active material may adopt the negative electrode active material for the battery known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0105] In some embodiments, the negative electrode film layer may further include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).

[0106] In some embodiments, the negative electrode film layer may further include a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

[0107] In some embodiments, the negative electrode film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0108] In some embodiments, the negative electrode sheet can be prepared in the following manner: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0109] [Electrolytes]

[0110] The electrolyte plays the role of conducting ions between the positive electrode and the negative electrode. The present application has no specific restrictions on the type of electrolyte, which can be selected according to needs. For example, the electrolyte can be liquid, gel or all-solid.

[0111] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.

[0112] In some embodiments, the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0113] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane sulfone, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0114] In some embodiments, the electrolyte may further include additives, such as negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.

[0115] [Isolation film]

[0116] In some embodiments, the battery cell further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical stability and mechanical stability can be selected.

[0117] In some embodiments, the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The isolation membrane can be a single-layer film or a multi-layer composite film, without particular limitation. When the isolation membrane is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0118] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly by a winding process or a lamination process.

[0119] The battery cell, battery and electrical device of the present application are described below with reference to the accompanying drawings.

[0120] The embodiment of the present application also provides a battery cell. Generally, a battery cell includes a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator. During the battery charging and discharging process, active ions are embedded and released back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte plays the role of conducting ions between the positive electrode sheet and the negative electrode sheet. The separator is arranged between the positive electrode sheet and the negative electrode sheet, mainly to prevent the positive and negative electrodes from short-circuiting, while allowing ions to pass through.

[0121] It should be understood that the "embedding" process described in this application refers to the process in which active ions are embedded in the positive electrode active material or the negative electrode active material due to an electrochemical reaction, and the "extraction" and "de-embedding" processes described in this application refer to the process in which active ions are extracted from the positive electrode active material or the negative electrode active material due to an electrochemical reaction.

[0122] In some embodiments, the battery cell may include an outer packaging, which may be used to encapsulate the electrode assembly and the electrolyte.

[0123] In some embodiments, the outer packaging of the battery cell may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the battery cell may also be a soft package, such as a bag-type soft package. The material of the soft package may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0124] The present application has no particular limitation on the shape of the battery cell, which may be cylindrical, square or any other shape. Figure 3 The battery cell 20 is a square structure as an example.

[0125] In some embodiments, reference Figure 4, the outer packaging may include a shell 21 and a cover plate 23. Among them, the shell 21 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 21 has an opening connected to the receiving cavity, and the cover plate 23 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can form an electrode assembly 22 through a winding process or a lamination process. The electrode assembly 22 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 22. The number of electrode assemblies 22 contained in the battery cell 20 can be one or more, and those skilled in the art can select according to specific actual needs.

[0126] In some embodiments, the battery 30 may include a plurality of battery cells 20. For example, Figure 5 , which is a schematic diagram of the structure of a battery 30 according to an embodiment of the present application, wherein the battery 30 may include a plurality of battery cells 20. The battery 30 may also include a box 31, wherein the box 31 is a hollow structure, and the plurality of battery cells 20 are accommodated in the box 31. For example, the plurality of battery cells 20 are connected in parallel, in series, or in a mixed combination and then placed in the box 31.

[0127] Optionally, the battery 30 may also include other structures, which are not described one by one here. For example, the battery 30 may also include a busbar component, which is used to realize electrical connection between multiple battery cells 20, such as parallel connection, series connection or mixed connection. Specifically, the busbar component can realize electrical connection between the battery cells 20 by connecting the electrode terminals of the battery cells 20. Furthermore, the busbar component can be fixed to the electrode terminals of the battery cells 20 by welding. The electrical energy of multiple battery cells 20 can be further led out through the box body 31 through a conductive mechanism. Optionally, the conductive mechanism may also belong to the busbar component.

[0128] According to different power requirements, the number of battery cells 20 can be set to any value. Multiple battery cells 20 can be connected in series, parallel or hybrid to achieve a larger capacity or power. Since the number of battery cells 20 included in each battery 30 may be large, for ease of installation, the battery cells 20 can be grouped, and each group of battery cells 20 constitutes a battery module. The number of battery cells 20 included in the battery module is not limited and can be set according to demand. The battery can include multiple battery modules, which can be connected in series, parallel or hybrid.

[0129] In addition, the present application also provides an electric device, which includes at least one of the battery cells, battery modules or batteries provided in the present application. The battery cells, battery modules or batteries can be used as the power source of the electric device, and can also be used as the energy storage unit of the electric device. The electric device may include mobile devices (such as mobile phones, 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., but are not limited thereto.

[0130] As the electrical device, a battery cell, a battery module or a battery can be selected according to its usage requirements.

[0131] Figure 6 The power consumption device is taken as an example. The power consumption device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. In order to meet the high power and high energy density requirements of the power consumption device for battery cells, batteries or battery modules can be used.

[0132] As another example, the device may be a mobile phone, a tablet computer, a notebook computer, etc. The device is usually required to be light and thin, and a battery cell may be used as a power source.

[0133] [Example]

[0134] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If no specific techniques or conditions are indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0135] 1. Preparation of positive electrode sheet

[0136] Positive electrode sheet 1: The positive electrode active material LiFePO4, the additive calcium carbide, the conductive agent conductive carbon black, and the binder polyvinylidene fluoride (PVDF) are dissolved in a solvent N-methylpyrrolidone (NMP) in a mass ratio of 94.95%:0.05%:2.5%:2.5%, and after stirring and mixing evenly, the mixture is coated on an aluminum foil, dried in an oven, and cold pressed and punched to obtain a positive electrode sheet 1.

[0137] Positive electrode sheet 2: The preparation of positive electrode sheet 2 is similar to that of positive electrode sheet 1, except that in positive electrode sheet 2, the mass ratio of positive electrode active material LiFePO4, additive calcium carbide, conductive agent conductive carbon black, and binder PVDF is 94.7%:0.3%:2.5%:2.5%.

[0138] Positive electrode sheet 3: The preparation of positive electrode sheet 3 is similar to that of positive electrode sheet 1, except that in positive electrode sheet 3, the mass ratio of positive electrode active material LiFePO4, additive calcium carbide, conductive agent conductive carbon black, and binder PVDF is 94.5%:0.5%:2.5%:2.5%.

[0139] Positive electrode sheet 4: The preparation of positive electrode sheet 4 is similar to that of positive electrode sheet 1, except that in positive electrode sheet 4, the mass ratio of positive electrode active material LiFePO4, additive calcium carbide, conductive agent conductive carbon black, and binder PVDF is 94.0%:1.0%:2.5%:2.5%.

[0140] Positive electrode sheet 5: The preparation of positive electrode sheet 5 is similar to that of positive electrode sheet 1, except that the additive in positive electrode sheet 5 is magnesium carbide.

[0141] Positive electrode sheet 6: The preparation of positive electrode sheet 6 is similar to that of positive electrode sheet 2, except that the additive in positive electrode sheet 6 is magnesium carbide.

[0142] Positive electrode sheet 7: The preparation of positive electrode sheet 7 is similar to that of positive electrode sheet 3, except that the additive in positive electrode sheet 7 is magnesium carbide.

[0143] Positive electrode plate 8: The preparation of positive electrode plate 8 is similar to that of positive electrode plate 4, except that the additive in positive electrode plate 8 is magnesium carbide.

[0144] Positive electrode sheet 9: The preparation of positive electrode sheet 9 is similar to that of positive electrode sheet 1, except that the additive in positive electrode sheet 9 is aluminum carbide.

[0145] Positive electrode sheet 10: The preparation of the positive electrode sheet 10 is similar to that of the positive electrode sheet 2, except that the additive in the positive electrode sheet 10 is aluminum carbide.

[0146] Positive electrode sheet 11: The preparation of the positive electrode sheet 11 is similar to that of the positive electrode sheet 3, except that the additive in the positive electrode sheet 11 is aluminum carbide.

[0147] Positive electrode sheet 12: The preparation of the positive electrode sheet 12 is similar to that of the positive electrode sheet 4, except that the additive in the positive electrode sheet 12 is aluminum carbide.

[0148] Positive electrode sheet 13: The preparation of positive electrode sheet 13 is similar to that of positive electrode sheet 1, except that positive electrode sheet 13 does not contain additives, and the mass ratio of positive electrode active material LiFePO4, conductive agent conductive carbon black, and binder PVDF is 95%:2.5%:2.5%.

[0149] Positive electrode sheet 14: The preparation of the positive electrode sheet 14 is similar to that of the positive electrode sheet 2, except that the additive in the positive electrode sheet 14 is potassium perfluorooctane sulfonate.

[0150] The prepared positive electrode sheet was tested for moisture: the positive electrode sheet was placed in a 100°C vacuum oven, baked for 6h and 12h respectively, and naturally cooled with the oven; 2g of the cold-pressed positive electrode sheet was taken, chopped in an environment with a dew point below -40°C, and placed in a moisture tester (Swiss Metrohm Karl Fischer Moisture Tester), the test temperature of the moisture tester was set to 170°C, heated for 10min, and then the moisture content of the positive electrode sheet was tested. The results are shown in Table 1.

[0151] 2. Preparation of lithium-ion batteries

[0152] [Example 1]

[0153] (1) Positive electrode

[0154] The positive electrode sheet adopts the positive electrode sheet 1 prepared as above.

[0155] (2) Preparation of negative electrode sheet

[0156] Graphite, conductive carbon black, sodium carboxymethyl cellulose and polystyrene-butadiene rubber are dispersed in a solvent deionized water in a mass ratio of 96%:1%:1%:2%, and after being stirred and mixed evenly, the mixture is coated on a copper foil, dried in an oven, and cold-pressed and punched to obtain a negative electrode sheet.

[0157] (3) Preparation of isolation membrane

[0158] Conventional polypropylene film was used as the isolation film.

[0159] (4) Preparation of electrolyte

[0160] In an argon atmosphere glove box with a water content of <10ppm, fully dried lithium hexafluorophosphate (LiPF6) was dissolved in a mixed solvent of ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) in a volume ratio of 20:20:60, and then the additive vinylene carbonate (VC) was added and mixed evenly to obtain an electrolyte. The concentration of the lithium salt was 1 mol / L.

[0161] (5) Assembly of lithium-ion battery: stack the positive electrode sheet 1, the separator, and the negative electrode sheet in order, so that the separator is between the positive electrode sheet 1 and the negative electrode sheet to play an isolating role, and then wind them to obtain an electrode assembly; place the electrode assembly in a battery casing, inject electrolyte after drying, and then undergo formation, standing and other processes to obtain a lithium-ion battery 1, which is Example 1.

[0162] [Example 2-12, Comparative Example 1-2]

[0163] The preparation methods of the lithium-ion batteries of Examples 2-12 and Comparative Examples 1-2 are similar to those of the lithium-ion battery of Example 1, except that different positive electrode sheets are used (among which, Examples 1-12 respectively use positive electrode sheets 1-12, and Comparative Examples 1-2 respectively use positive electrode sheets 13-14), as shown in Table 1 for details.

[0164] Next, the battery performance testing process is described.

[0165] 3. Battery performance test

[0166] (1) 55℃ high temperature cycle test

[0167] Place the battery in a constant temperature box at 55°C, first charge the lithium-ion battery to 3.65V at a constant current of 2A; further charge at a constant voltage of 3.65V to a current of 250mA, and let it rest for 5 minutes; then discharge the lithium-ion battery to 2.5V at a constant current of 2A, and let it rest for 5 minutes; this is a charge and discharge cycle process, and the discharge capacity this time is the discharge capacity of the first cycle. The lithium-ion battery is subjected to multiple cycle charge and discharge tests in the above manner, and the discharge capacity of the 500th cycle is detected, and the capacity retention rate of the lithium-ion battery after the cycle is calculated by the following formula. The capacity retention rate of the battery after 500 cycles (%) = [discharge capacity of the 500th cycle / discharge capacity of the first cycle] × 100%.

[0168] (2) 55℃ high temperature storage test

[0169] At room temperature of 25℃, the lithium-ion battery is first charged to 3.65V at a constant current of 2A; further charged to a current of 250mA at a constant voltage of 3.65V and rested for 5min; then the lithium-ion battery is discharged to 2.5V at a constant current of 2A and rested for 5min; the lithium-ion battery is charged to 3.65V at a constant current of 2A again; and charged to a current of 250mA at a constant voltage of 3.65V again, and the lithium-ion battery is fully charged, with an initial full charge capacity of Q.

[0170] The fully charged lithium-ion battery was placed in a 55° C. constant temperature box for 7 days.

[0171] The lithium-ion battery that had been left standing for 7 days was then left standing at room temperature of 25°C for 4 hours. After the battery temperature returned to room temperature of 25°C, the lithium-ion battery was discharged to 2.5V at a constant current of 2A, and the discharge capacity Q1 of the lithium-ion battery was detected. The battery was left standing for 5 minutes.

[0172] Then the lithium-ion battery is charged to 3.65V at a constant current of 2A; charged to a current of 250mA at a constant voltage of 3.65V and left to rest for 5 minutes; and then the lithium-ion battery is discharged to 2.5V at a constant current of 5A, and the discharge capacity Q2 of the lithium-ion battery is obtained by detection.

[0173] After the battery is stored at a high temperature of 55°C for 7 days, the capacity retention rate (%) = [Q1 / Q] × 100%; the capacity recovery rate (%) = [Q2 / Q] × 100%.

[0174] The battery performances of Examples 1-12 and Comparative Examples 1-2 prepared were tested according to the above method. The results are shown in Table 1.

[0175] Table 1: Product parameters and performance test results of comparative examples and different embodiments

[0176]

[0177]

[0178] From the comparison of the results of comparative example 1-2 and example 1-12, it can be seen that by adding metal carbide additives to the coating of the positive electrode plate, the moisture content of the positive electrode plate is reduced more after being baked in the oven, and the corresponding lithium-ion battery has better cycle performance and storage stability.

[0179] From the comparison of the results of Examples 1-4, the comparison of the results of Examples 5-8, and the comparison of the results of Examples 9-12, it can be seen that within a certain range, the higher the additive content in the coating of the positive electrode sheet, the better the corresponding cycle performance and storage stability of the lithium-ion battery. When the additive content in the coating of the positive electrode sheet reaches a certain value, as the additive content increases, the performance improvement effect of the lithium-ion battery changes little. For example, in Example 4 relative to Example 3, the mass content of the additive in the coating is increased from 0.5% to 1.0%, and the cycle performance and storage stability of the lithium-ion battery are improved to a certain extent, but the improvement effect is not obvious. At the same time, since the additive content is doubled, the mass content of the positive electrode active material is reduced, which will reduce the energy density of the lithium-ion battery. Similarly, for example, Example 8 relative to Example 7 and Example 12 relative to Example 11. In the embodiments of the present application, under the same other conditions, the mass content of the additive in the coating of the positive electrode sheet is in the range of 0.05% to 0.5%, and the corresponding cycle performance and storage stability of the lithium-ion battery are significantly improved.

[0180] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and the same effect as the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A positive electrode sheet, characterized in that: include: Positive electrode current collector; A coating layer is disposed on a surface of at least one side of the positive electrode current collector, the coating layer comprises a positive electrode active material and an additive, and the additive comprises a metal carbide.

2. The positive electrode sheet according to claim 1, characterized in that: The additive includes at least one of calcium carbide, magnesium carbide and aluminum carbide.

3. The positive electrode sheet according to claim 1 or 2, characterized in that: Based on the total mass of the coating, the mass content of the additive in the coating ranges from 0.05% to 0.5%.

4. The positive electrode sheet according to any one of claims 1 to 3, characterized in that: The positive electrode active material includes at least one of an olivine structure phosphate material, a spinel material, and a layered transition metal oxide.

5. The positive electrode sheet according to claim 4, characterized in that: The olivine structure phosphate material includes Li a Fe b M 1-b P 1-m O 4-n , wherein M includes at least one of the other metal elements except Fe, wherein 0≤a≤1.1, 0.3≤b≤1, 0≤m≤0.1, 0≤n≤0.1, optionally, M includes at least one of Mn, Al, Cu, Mg, Zn, Ni, Ti, V, Zr, Co, Ga, Sn, Sb, Nb and Ge, optionally, the olivine structure phosphate material includes at least one of lithium iron phosphate and lithium manganese iron phosphate.

6. The positive electrode sheet according to claim 4 or 5, characterized in that: The spinel material includes LiNi c Mn 2-c O4, wherein 0≤c<2, optionally, the spinel material comprises lithium manganate.

7. The positive electrode sheet according to any one of claims 4 to 6, characterized in that: The layered transition metal oxides include LiCoO2, LiMnO2, LiNiO2, Li a’ Ni x Co y M 1 1-x-y O 2+d 、zLi2MnO3·(1-z)LiM 2 O2 at least one, wherein M 1 Including at least one of Mn, Zr, Al, B, Ta, Mo, W, Nb, Sb, La, M 2 The layered transition metal oxide comprises at least one of Co, Ni and Mn, 0.5≤x≤1.0, 0≤y<0.5, x+y<1, 0.2≤a'<1.2, -0.02≤d<0.02, 0<z<1, and optionally, the layered transition metal oxide comprises Li(Ni 0.6 Co 0.2 Mn 0.2 ) 1.15 O2、Li(Ni 0.5 Co 0.2 Mn 0.3 ) 1.07 At least one of O2.

8. The positive electrode sheet according to any one of claims 1 to 7, characterized in that: Based on the total mass of the coating, the mass content of the positive electrode active material in the coating ranges from 93% to 99%.

9. The positive electrode sheet according to any one of claims 1 to 8, characterized in that: The coating further comprises a conductive agent, and the conductive agent comprises at least one of conductive carbon black, superconducting carbon, carbon dots, carbon nanotubes, graphene, and Ketjen black.

10. The positive electrode sheet according to any one of claims 1 to 9, characterized in that: The coating layer further includes a binder, and the binder includes at least one of polyvinylidene fluoride, polyacrylonitrile, polyacrylate, polyacrylic acid, and acrylonitrile-acrylate-acrylic acid copolymer.

11. The positive electrode sheet according to claim 10, characterized in that: Based on the total mass of the coating, the mass content of the binder in the coating ranges from 1% to 5%.

12. A method for preparing a positive electrode sheet, characterized in that: include: Providing a positive electrode current collector, and disposing a coating on the positive electrode current collector; The coating is disposed on the surface of at least one side of the positive electrode current collector, and the coating comprises a positive electrode active material and an additive, wherein the additive comprises a metal carbide.

13. A battery cell, characterized in that: The invention comprises a positive electrode sheet according to any one of claims 1 to 11.

14. A battery, characterized in that: Comprising the battery cell according to claim 13.

15. An electrical device, characterized in that: Comprising a battery according to claim 14.

Images