Battery monomer, battery device and electric device

Abstract

The invention provides a battery monomer, a battery device and a power utilization device, and belongs to the technical field of batteries. Wherein the battery monomer comprises a positive electrode plate, a positive electrode film layer of the positive electrode plate comprises a positive electrode additive, and the positive electrode additive comprises a first polymer and a second polymer; the first polymer comprises a fluorine-containing olefin polymer; the second polymer comprises an anchoring group G and a flexible chain segment, the anchoring group G contains at least one of carboxyl, sulfonic acid group, phosphate group, amide group and ester group, and the main chain of the flexible chain segment contains at least one of carbon-carbon single bond, carbon-oxygen single bond, ether bond, ester bond and amido bond. Through cooperation of the first polymer and the second polymer, the stability of the small-particle-size positive electrode active material slurry can be improved.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a battery cell, a battery device, and an electrical device. Background Technology

[0002] Driven by the need for longer battery life, the particle size of the positive electrode active material in batteries is constantly decreasing. This is because reducing the particle size of the positive electrode active material can increase the specific surface area and shorten the diffusion distance of active ions, thereby helping to improve energy density.

[0003] However, the smaller the particle size of the positive electrode active material, the higher its surface energy, which makes it difficult for the positive electrode active material to disperse in the solvent, and the stability of the formed positive electrode slurry is poor, making it prone to gelation.

[0004] Although there are solutions in related technologies to improve stability by increasing the molecular weight of the binder, high molecular weight binders have higher viscosity and the problem of slurry gelation still occurs. Summary of the Invention

[0005] In view of the above problems, this application provides a battery cell, a battery device, and an electrical device, which aims to improve the problem of poor stability of small-particle-size positive electrode active material slurry.

[0006] In a first aspect, this application provides a battery cell including a positive electrode sheet, the positive electrode sheet including a positive electrode film layer, the positive electrode film layer including a positive electrode additive, and the positive electrode additive including a first type of polymer and a second type of polymer;

[0007] The first type of polymers includes fluorinated olefin polymers;

[0008] The second type of polymer includes an anchoring group G and a flexible segment. The anchoring group G includes at least one of carboxyl, sulfonic acid, phosphate, amide, and ester groups. The main chain of the flexible segment includes at least one of carbon-carbon single bonds, carbon-oxygen single bonds, ether bonds, ester bonds, and amide bonds.

[0009] In the technical solution of this application, the first type of polymer acts as a binder, which can firmly bond the positive electrode active material and the conductive agent, and can adhere the mixed system formed by the positive electrode active material and the conductive agent to the current collector, thereby reducing the separation and detachment of the positive electrode film layer. The second type of polymer contains anchoring groups and flexible segments. The anchoring groups can enhance the adsorption capacity between the polymer and the surface of different particles, and improve the dispersion performance; the flexible segments play a steric hindrance role, which can reduce the re-agglomeration of powder after dispersion. Therefore, this application can improve the stability of small-particle-size positive electrode active material slurry.

[0010] In some embodiments, the flexible segment further includes at least one branch, which includes at least one of carbon chain, benzene ring, acid anhydride, polyether, and cyclic ether.

[0011] In the technical solution of this application, the cooperation between the branches and the main chain of the flexible chain segment can enhance the slippage ability between particles. When the positive electrode film layer is coated onto the positive electrode current collector with a high compaction density, it can increase the flexibility of the formed positive electrode sheet, thereby improving the problem of unevenness in the cross-section when the film roll is cut. When forming a stacked battery, it can reduce the risk of puncturing the separator at the unevenness of the cut edge, thereby improving the stability of the battery.

[0012] In some embodiments, the structural formula of the second type of polymer is shown in formula (I):

[0013]

[0014] In the technical solution of this application, the introduction of rigid structures such as benzene rings and acid anhydrides into the side chains of the second type of polymer can enhance the ability of the second type of polymer to embed into the first type of polymer, thereby reducing the crystallinity of the first type of polymer and thus enhancing the flexibility of the positive electrode sheet; using ethylene oxide and anchoring groups as end caps can improve the dispersion ability of particles and enhance the flexibility of the formed positive electrode sheet.

[0015] In some embodiments, the anchoring group G is a group represented by formula (II) or formula (III):

[0016] Equation (II)

[0017] Equation (III);

[0018] Wherein, the C n It is an alkyl carbon chain, wherein R" includes hydrogen atoms, C1-C 12 Alkyl carbon chain, C1-C 12 Alkyl alcohols, C1-C 12 At least one of alkyl hydroxylamines.

[0019] In the technical solution of this application, the anchoring group G includes an ester group or a sulfonic acid group. The ester group has a certain polarity, which allows it to interact with polar groups or charged sites on the particle surface, thereby establishing a connection between the polymer and the particles and enhancing the adsorption force. The sulfonic acid group can form hydrogen bonds with polar groups (such as hydroxyl and amino groups) on the particle surface, thereby making the polymer and particles tightly bound and enhancing the adsorption effect. On the other hand, the sulfonic acid group can provide a certain steric hindrance, thereby reducing the phenomenon of particle aggregation and precipitation.

[0020] In some embodiments, the anchoring group G is a group represented by formula (IV) or formula (V):

[0021]

[0022] Wherein, R" includes hydrogen atoms, C1-C 12 Alkyl carbon chain, C1-C 12 Alkyl alcohols, C1-C 12 At least one of alkyl hydroxylamines.

[0023] In the technical solution of this application, the anchoring group G contains a phosphate ester group. The phosphate ester group can make the polymer and particles tightly bonded through electrostatic attraction and hydrogen bonding, thereby enhancing the adsorption force and improving the dispersibility and stability of the slurry. In addition, the phosphate ester group can also provide a certain steric hindrance. This steric hindrance effect can keep the particles in a dispersed state under the action of the polymer.

[0024] In some embodiments, the anchoring group G is a group represented by formula (VI) or formula (VII):

[0025]

[0026] Wherein, R3 and R5 are both C1-C 12 Alkylhydroxylamine, R4 includes a hydrogen atom, C1-C 12 Alkyl carbon chain, C1-C 12 At least one of alkyl alcohols.

[0027] In the technical solution of this application, the anchoring group G contains a diamide group or a diester group. The amide group can bind the polymer and particles tightly through hydrogen bonding, electrostatic attraction and van der Waals forces.

[0028] In some embodiments, the polymer monomers of the first type of polymer include at least one of the compounds shown in formula (VIII) and formula (IX):

[0029]

[0030]

[0031] Both R1 and R2 include hydrogen atoms and C1-C atoms. 12 Alkyl carbon chain, C1-C 12 The alkyl group contains at least one of the following: a benzene ring carbon chain, a polyether segment, or a polyoxyethylene ether-polyoxypropylene ether copolymer segment.

[0032] In the technical solution of this application, the polymer monomer of the fluorinated olefin polymer can be at least one of vinylidene fluoride, vinylidene fluoride derivatives, and hexafluoropropylene. R1 and R2 of the vinylidene fluoride derivatives can be at least one of alkyl carbon chains, alkyl carbon chains containing benzene rings, polyether segments, and polyoxyethylene ether-polyoxypropylene ether copolymer segments. The introduction of the above groups can increase the adhesion between particles and between particles and the positive electrode current collector, reduce the sliding resistance between particle molecules, and improve the flexibility of the electrode.

[0033] In some embodiments, the positive electrode additive accounts for 0.01%-3% of the mass of the positive electrode film.

[0034] In the technical solution of this application, a low content of positive electrode additives can meet the requirements for improving the stability of positive electrode slurry, which can increase the loading of positive electrode active materials and thus improve the energy density of the battery. In addition, a low content of positive electrode additives can reduce the cycle DC resistance (DCR) of the battery cell, thereby improving the cycle and storage life of the cell.

[0035] In some embodiments, the first type of polymer accounts for 0.5%-1.1% of the mass of the positive electrode film layer; and / or, the second type of polymer accounts for 0.16%-0.36% of the mass of the positive electrode film layer.

[0036] In the technical solution of this application, limiting the mass ratio of the first type of polymer and the second type of polymer to a low range can further improve the loading and energy density of the positive electrode active material.

[0037] In some embodiments, the coating thickness of the positive electrode film is 100μm-120μm.

[0038] In the technical solution of this application, the loading of positive electrode active material can be increased by thick coating of positive electrode film layer. In addition, positive electrode film layer contains positive electrode additives, which can improve the flexibility of electrode sheet and reduce cracking and detachment on the basis of thick coating.

[0039] Secondly, this application provides a battery device including any of the aforementioned battery cells.

[0040] Thirdly, this application provides an electrical device, including the aforementioned battery device.

[0041] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0042] Figure 1This is a schematic diagram of the vehicle structure in some embodiments of this application;

[0043] Figure 2 This is an exploded view of the battery device in some embodiments of this application;

[0044] Figure 3 This is a schematic diagram of the structure of a single battery cell in some embodiments of this application;

[0045] Figure 4 This is a schematic diagram showing the exploded structure of a single battery cell in some embodiments of this application.

[0046] Explanation of reference numerals in the attached figures:

[0047] 1000 vehicles;

[0048] Battery unit 100, controller 200, motor 300;

[0049] Box 10, Part 11, Part 2 12;

[0050] Battery cell 20, end cap 21, casing 22, cell assembly 23. Detailed Implementation

[0051] The following embodiments are only used to illustrate the technical solutions of this application more clearly, and are therefore only examples and should not be used to limit the scope of protection of this application.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0053] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0054] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0055] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0056] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces). The term "at least one" refers to one or more.

[0057] The particle size of the positive electrode active material affects the energy density of the battery. When the particle size of the positive electrode active material decreases, on the one hand, it can increase the specific surface area of ​​the positive electrode active material. The increase in specific surface area means that more active material surface is exposed in the electrolyte, which can fully contact the electrolyte, thus providing more reaction sites for electrochemical reactions. This makes the insertion and extraction reactions of active ions at the electrode and electrolyte interface easier and faster, thereby increasing the charge and discharge capacity of the battery cell and thus increasing the energy density. On the other hand, the smaller particle size of the positive electrode active material can shorten the diffusion distance of active ions, thereby accelerating the diffusion rate of active ions. This allows more active ions to participate in the reaction in the same amount of time, improving the rate performance and energy output efficiency of the battery cell, which helps to increase the energy density.

[0058] Based on the above mechanism, in order to improve the energy density of battery cells, the particle size of positive electrode active materials is becoming smaller and smaller, even reaching the nanometer level. However, the problem that arises is that the smaller the particle size, the higher the surface energy, which makes the positive electrode active material difficult to disperse in solvents, and the resulting positive electrode slurry has poor stability and is prone to gelation.

[0059] Related technologies increase the molecular weight of binders to the million level to address issues of poor dispersibility and stability. High molecular weight binders exhibit stronger intermolecular forces, enabling them to better bind particles such as positive electrode active materials and conductive agents together. This stronger binding effect can, to some extent, create a relatively stable structure between particles, reducing particle aggregation and thus improving dispersion performance. Furthermore, the longer molecular chains of high molecular weight binders can create a greater steric hindrance effect in the slurry, reducing particle aggregation and further contributing to improved dispersion. However, high molecular weight binders also have high viscosity, making slurry gelation a common problem.

[0060] To this end, a battery cell is designed and disclosed, wherein the positive electrode film layer includes a positive electrode additive, which includes a first type of polymer and a second type of polymer; the first type of polymer includes a fluorinated olefin polymer; the second type of polymer includes an anchoring group G and a flexible segment, wherein the anchoring group G contains at least one of carboxyl group, sulfonic acid group, phosphate ester group, amide group, and ester group, and the main chain of the flexible segment contains at least one of carbon-carbon single bond, carbon-oxygen single bond, ether bond, ester bond, and amide bond.

[0061] In such battery cells, the first type of polymer acts as a binder, firmly bonding the positive electrode active material and the conductive agent, and adhering the mixture formed by the positive electrode active material and the conductive agent to the current collector, thereby reducing the separation and detachment of the positive electrode film. The second type of polymer contains anchoring groups and flexible segments. The anchoring groups enhance the adsorption capacity between the polymer and the surfaces of different particles, improving dispersion performance; the flexible segments act as steric hindrance, reducing the re-agglomeration of powder after dispersion.

[0062] The battery cells disclosed in this application can be used, but are not limited to, in electrical devices such as vehicles, ships, or aircraft. The battery cells can be either secondary or primary batteries. A power system for such an electrical device can also be composed of a battery assembly using the battery devices disclosed in this application.

[0063] This application provides an electrical device that uses a battery as a power source. The electrical device can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0064] For ease of explanation, the following embodiments will be described using a vehicle 1000 as an example of an electrical device according to an embodiment of this application.

[0065] Reference Figure 1 As shown, vehicle 1000 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A battery device 100 is installed inside vehicle 1000, and the battery device 100 can be located at the bottom, front, or rear of vehicle 1000. The battery device 100 can be used to power vehicle 1000; for example, the battery device 100 can serve as the operating power source for vehicle 1000. Vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery device 100 to supply power to the motor 300, for example, to meet the power needs of vehicle 1000 during starting, navigation, and driving.

[0066] In some embodiments of this application, the battery device 100 can not only serve as the operating power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0067] Reference Figure 2 As shown, the battery device 100 may include a housing 10 and a battery cell 20, with the battery cell 20 housed within the housing 10. The housing 10 provides a space for the battery cell 20 and can have various structures. In some embodiments, the housing 10 may include a first portion 11 and a second portion 12, which overlap each other, collectively defining a space for accommodating the battery cell 20. The second portion 12 may be a hollow structure with one open end, and the first portion 11 may be a plate-like structure, covering the open side of the second portion 12 so that the first portion 11 and the second portion 12 together define the space. Alternatively, both the first portion 11 and the second portion 12 may be hollow structures with one open side, with the open side of the first portion 11 covering the open side of the second portion 12. Of course, the housing 10 formed by the first portion 11 and the second portion 12 can have various shapes, such as a cylinder, a cuboid, etc.

[0068] In the battery device 100, there can be multiple battery cells 20, which can be connected in series, parallel, or in a mixed manner. A mixed connection means that multiple battery cells 20 are connected in both series and parallel configurations. Multiple battery cells 20 can be directly connected in series, parallel, or in a mixed manner, and then the entire assembly of the multiple battery cells 20 is housed within the housing 10. Alternatively, the battery device 100 can also consist of multiple battery cells 20 first connected in series, parallel, or in a mixed manner to form battery modules, and then these battery modules are connected in series, parallel, or in a mixed manner to form a whole, which is also housed within the housing 10. The battery 100 may also include other structures; for example, the battery device 100 may also include a busbar component for electrical connection between the multiple battery cells 20.

[0069] The battery cell 20 can be a lithium-ion battery, a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited to these. The battery cell 20 can be cylindrical, flat, cuboid, or other shapes.

[0070] refer to Figure 3 and 4 As shown, the battery cell 20 refers to the smallest unit that makes up a battery. The battery cell 20 includes an end cap 21, a housing 22, a cell assembly 23, and other functional components.

[0071] End cap 21 refers to a component that covers the opening of housing 22 to isolate the internal environment of battery cell 20 from the external environment. The shape of end cap 21 can be adapted to the shape of housing 22 to fit it. Optionally, end cap 21 can be made of a material with certain hardness and strength (such as aluminum alloy), so that end cap 21 is not easily deformed under pressure or impact, allowing battery cell 20 to have higher structural strength. Functional components such as electrode terminals can be provided on end cap 21. Electrode terminals can be used for electrical connection with cell assembly 23 to output or input electrical energy to battery cell 20. In some embodiments, end cap 21 can also be provided with a pressure relief mechanism for releasing internal pressure when the internal pressure or temperature of battery cell 20 reaches a threshold. The material of end cap 21 can also be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this application embodiment does not impose any special limitations on this. In some embodiments, an insulating element may be provided on the inner side of the end cap 21. The insulating element can be used to isolate the electrical connection components within the housing 22 from the end cap 21 to reduce the risk of short circuits. For example, the insulating element may be made of plastic, rubber, etc.

[0072] The housing 22 is a component used to cooperate with the end cap 21 to form the internal environment of the battery cell 20. This internal environment can accommodate the cell assembly 23, electrolyte, and other components. The housing 22 and the end cap 21 can be independent components. An opening can be provided on the housing 22, and the end cap 21 can be used to close the opening to form the internal environment of the battery cell 20. Alternatively, the end cap 21 and the housing 22 can be integrated. Specifically, the end cap 21 and the housing 22 can form a common connecting surface before other components are inserted into the housing. When it is necessary to encapsulate the interior of the housing 22, the end cap 21 closes the housing 22. The housing 22 can be of various shapes and sizes, such as cuboid, cylindrical, hexagonal prism, etc. Specifically, the shape of the housing 22 can be determined according to the specific shape and size of the cell assembly 23. The material of the housing 22 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. This application embodiment does not impose any special limitations on this.

[0073] The cell assembly 23 is the component in the battery cell 20 where the electrochemical reaction occurs. The casing 22 may contain one or more cell assemblies 23. The cell assembly 23 is mainly formed by winding or stacking positive and negative electrode sheets, and typically a separator is provided between the positive and negative electrode sheets. The portions of the positive and negative electrode sheets containing active material constitute the main body of the cell assembly, while the portions without active material each constitute a tab. The positive and negative tabs may be located together at one end of the main body or separately at both ends of the main body. During the charging and discharging process of the battery, the positive and negative active materials react with the electrolyte, and the tabs connect to the electrode terminals to form a current loop.

[0074] Of course, in some other embodiments, the battery cell 20 can also be directly installed in the battery pack or integrated with the chassis / body.

[0075] According to some embodiments of this application, this application provides a battery cell including a positive electrode sheet, the positive electrode sheet including a positive electrode film layer, the positive electrode film layer including a positive electrode additive, the positive electrode additive including a first type of polymer and a second type of polymer; the first type of polymer includes a fluorinated olefin polymer; the second type of polymer includes an anchoring group G and a flexible segment, the anchoring group G including at least one of carboxyl group, sulfonic acid group, phosphate ester group, amide group, and ester group, and the main chain of the flexible segment including at least one of carbon-carbon single bond, carbon-oxygen single bond, ether bond, ester bond, and amide bond.

[0076] Typically, a battery cell includes a positive electrode, a negative electrode, an electrolyte, and a separator. During charging and discharging, active ions move back and forth between the positive and negative electrodes, inserting and releasing. The electrolyte acts as a conductor of ions between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, primarily prevents short circuits while allowing ions to pass through.

[0077] The positive electrode includes a positive current collector and the aforementioned positive electrode film layer, with the positive electrode film layer disposed on at least one surface of the positive current collector. In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be formed by forming a metal material (aluminum, aluminum 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.).

[0078] In addition to the aforementioned positive electrode additives, the positive electrode film also includes a positive electrode active material. When the battery cell is a lithium-ion battery, the positive electrode active material can be a known positive electrode active material for lithium-ion batteries. As an example, the positive electrode active material may include at least one of the following materials: lithium phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNiO2). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05 At least one of O2 and its modified compounds. Examples of lithium phosphates with an olivine structure include, but are not limited to, lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0079] In some embodiments, the positive electrode film layer may optionally include a binder. As an example, the binder may include at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0080] In some embodiments, the positive electrode film may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0081] The negative electrode includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector. In some embodiments, the negative current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can 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.).

[0082] In some embodiments, the negative electrode active material may be a negative electrode active material known in the art for use in batteries. 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, and 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, this application is not limited to these materials, and other conventional 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.

[0083] In some embodiments, the negative electrode film layer may optionally 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).

[0084] In some embodiments, the negative electrode film may optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0085] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0086] The electrolyte acts as a conductor of ions between the positive and negative electrodes. In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent. Exemplarily, the electrolyte salt may 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 difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate. The solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0087] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve the overcharge performance of individual battery cells, additives that improve the high-temperature or low-temperature performance of individual battery cells, etc.

[0088] The material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film; there are no particular restrictions. When the separator is a multi-layer composite film, the materials of each layer can be the same or different; there are no particular restrictions.

[0089] For the design of positive electrode additives in the positive electrode film, the first type of polymer includes fluorinated olefin polymers. Fluorinated olefin polymers refer to polymers formed by the polymerization of olefins with fluorine substituents. Fluorinated olefin polymers have good bonding properties and can firmly bond particles such as positive electrode active materials and conductive agents. They can also firmly bond the mixture of positive electrode active materials and conductive agents to the current collector, thereby reducing the separation and detachment of the positive electrode film.

[0090] The anchoring groups in the second type of polymers refer to chemical groups that can firmly bind to particles through chemical bonds or intermolecular forces. Anchoring groups can enhance the adsorption capacity between polymers and different particle surfaces, thereby improving dispersion performance.

[0091] A flexible segment refers to a segment of a chain with high flexibility and deformability. The backbone of a flexible segment is the longest continuous chain connecting the repeating units. The backbone of a flexible segment can include at least one of carbon-carbon single bonds, carbon-oxygen single bonds, ether bonds, ester bonds, and amide bonds. Carbon-carbon single bonds can rotate freely, allowing the segment to easily change its shape and conformation, thus exhibiting high flexibility. Carbon-oxygen single bonds are similar, also rotating freely, allowing segments containing carbon-oxygen single bonds to change their shape and conformation to a certain extent, exhibiting flexibility. The bond angle of an ether bond is approximately 110°, which gives it a certain degree of rotatability in space. Compared to other chemical bonds, ether bonds have a relatively long bond length, further increasing their flexibility. Furthermore, the oxygen atom in an ether bond carries two lone pairs of electrons, which can form weak interactions with surrounding atoms or molecules, such as hydrogen bonds. These weak interactions result in a looser electron cloud distribution around the ether bond, increasing its flexibility. Ester bonds are less free to rotate than carbon-carbon single bonds and ether bonds, but they still allow for some bending and twisting of the chain segment, thus exhibiting a certain degree of flexibility. Amide bonds can rotate and bend to some extent, giving chain segments containing amide bonds a certain degree of flexibility, but the flexibility of amide bonds is slightly weaker than that of carbon-carbon single bonds, carbon-oxygen single bonds, ether bonds, and ester bonds.

[0092] Flexible segments can impart good adhesion and flexibility to the cathode film, thereby reducing the occurrence of film cracking and detachment. In addition, flexible segments act as steric hindrance, which can reduce the re-agglomeration of powder after dispersion. Therefore, this application can improve the stability of small-particle-size cathode active material slurry.

[0093] According to some embodiments of this application, the flexible segment further includes at least one branch, which includes at least one of carbon chain, benzene ring, acid anhydride, polyether, and cyclic ether.

[0094] A branch chain is a shorter segment that branches off from the main chain in a flexible chain segment. It can be linear or branched.

[0095] The combination of the side chains and main chains of the flexible segments can enhance the slippage ability between particles. When the positive electrode film layer is coated onto the positive electrode current collector with a high compaction density, it can increase the flexibility of the formed positive electrode sheet, thereby improving the problem of unevenness in the cross-section when the film roll is cut. When forming a stacked battery, it can reduce the risk of puncturing the separator at the uneven cut edge, thereby improving the stability of the battery.

[0096] According to some embodiments of this application, the structural formula of the second type of polymer is shown in formula (I):

[0097]

[0098] The second type of polymer structure contains benzene rings and acid anhydrides in its branched chains. As rigid structures, benzene rings and acid anhydrides can enhance the ability of the second type of polymer to embed into the first type of polymer, thereby reducing the crystallinity of the first type of polymer and thus enhancing the flexibility of the positive electrode sheet. Using ethylene oxide and anchoring groups as end caps can improve the dispersion ability of particles and enhance the flexibility of the formed positive electrode sheet.

[0099] According to some embodiments of this application, the anchoring group G is a group represented by formula (II) or formula (III):

[0100] Equation (II)

[0101] Equation (III);

[0102] Among them, C n It is an alkyl carbon chain, where R" includes hydrogen atoms, C1-C 12 Alkyl carbon chain, C1-C 12 Alkyl alcohols, C1-C 12 At least one of alkyl hydroxylamines.

[0103] The anchoring group G shown in formula (II) contains an ester group with a weight-average molecular weight of 500-5000, while the anchoring group G shown in formula (III) contains a sulfonic acid group with a weight-average molecular weight of 500-2000. The ester group has a certain polarity, which allows it to interact with polar groups or charged sites on the particle surface, thereby establishing a connection between the polymer and the particles and enhancing adsorption. The sulfonic acid group can form hydrogen bonds with polar groups (such as hydroxyl and amino groups) on the particle surface, thus tightly binding the polymer to the particles and enhancing the adsorption effect. Furthermore, the sulfonic acid group can provide steric hindrance, thereby reducing the aggregation and precipitation of particles.

[0104] According to some embodiments of this application, the anchoring group G is a group represented by formula (IV) or formula (V):

[0105]

[0106] Wherein, R" includes hydrogen atoms, C1-C 12 Alkyl carbon chain, C1-C 12 Alkyl alcohols, C1-C 12 At least one of alkyl hydroxylamines.

[0107] The anchoring group G shown in formula (IV) contains phosphate ester groups with a weight-average molecular weight of 500, while the anchoring group G shown in formula (V) also contains sulfonic acid groups with a weight-average molecular weight of 100-2000. The phosphate ester groups can enhance the adsorption force by tightly binding the polymer to the particles through electrostatic attraction and hydrogen bonding, thereby improving the dispersibility and stability of the slurry. Furthermore, the phosphate ester groups can also provide steric hindrance, which helps maintain the dispersion of particles under the influence of the polymer.

[0108] According to some embodiments of this application, the anchoring group G is a group represented by formula (VI) or formula (VII):

[0109]

[0110] Among them, R3 and R5 are both C1-C 12 Alkylhydroxylamine, R4 includes a hydrogen atom, C1-C 12 Alkyl carbon chain, C1-C 12 At least one of alkyl alcohols.

[0111] The anchoring group G shown in formula (VI) includes a diamide group with a weight-average molecular weight of 100-300, while the anchoring group G shown in formula (VII) includes a diester group with a weight-average molecular weight of 100-2000. The amide group can tightly bind the polymer to the particles through hydrogen bonding, electrostatic attraction, and van der Waals forces.

[0112] According to some embodiments of this application, the polymer monomers of the first type of polymer include at least one of the compounds shown in formula (VIII) and formula (IX):

[0113]

[0114] Both R1 and R2 contain hydrogen atoms and C1-C atoms. 12 Alkyl carbon chain, C1-C 12 The alkyl group contains at least one of the following: a benzene ring carbon chain, a polyether segment, or a polyoxyethylene ether-polyoxypropylene ether copolymer segment.

[0115] The compound represented by formula (VIII) is vinylidene fluoride and its derivatives, and the compound represented by formula (IX) is hexafluoropropylene. That is, the polymer monomer of the fluorinated olefin polymer can be at least one of vinylidene fluoride, vinylidene fluoride derivatives, and hexafluoropropylene. R1 and R2 of the vinylidene fluoride derivative can be at least one of alkyl carbon chains, alkyl carbon chains containing benzene rings, polyether segments, and polyoxyethylene ether-polyoxypropylene ether copolymer segments. The introduction of the above groups can increase the adhesion between particles and between particles and the positive electrode current collector, reduce the sliding resistance between particle molecules, and improve the flexibility of the electrode.

[0116] According to some embodiments of this application, the mass percentage of the positive electrode additive in the positive electrode film layer is 0.01%-3%.

[0117] The mass percentage of the positive electrode additive in the positive electrode film layer is 0.01%-3%, meaning the mass fraction of the positive electrode additive can be any value between 0.01% and 3%. For example, the mass fraction of the positive electrode additive can be 0.01%, 0.03%, 0.05%, 1%, 1.5%, 2%, 2.5%, or 3%. A low content of positive electrode additive can meet the requirements for improving the stability of the positive electrode slurry, thus increasing the loading of the positive electrode active material and thereby improving the energy density of the battery. Furthermore, a low content of positive electrode additive can reduce the cycle DC resistance (DCR) of the battery cell, thereby improving the cell's cycle and storage life.

[0118] According to some embodiments of this application, the mass percentage of the first type of polymer in the positive electrode film layer is 0.5%-1.1%; and / or, the mass percentage of the second type of polymer in the positive electrode film layer is 0.16%-0.36%.

[0119] The mass percentage of the first type of polymer in the positive electrode film layer is 0.5%-1.1%, which means that the mass fraction of the first type of polymer can be any value between 0.5% and 1.1%. For example, the mass fraction of the first type of polymer can be 0.5%, 0.7%, 0.9%, 1.0%, or 1.1%.

[0120] The mass percentage of the second type of polymer in the positive electrode film layer is 0.16%-0.36%, which means that the mass fraction of the second type of polymer can be any value between 0.01% and 0.06%. For example, the mass fraction of the second type of polymer can be 0.16%, 0.20%, 0.23%, 0.25%, 0.30%, or 0.36%.

[0121] Limiting the mass percentage of the first and second polymers to a low range can further improve the loading and energy density of the positive electrode active material.

[0122] According to some embodiments of this application, the coating thickness of the positive electrode film is 100μm-120μm.

[0123] The coating thickness of the positive electrode film is 100μm-120μm, which means that the thickness of the positive electrode film can be any value between 100 and 120. For example, the thickness of the positive electrode film can be 100μm, 102μm, 105μm, 110μm, 115μm or 120μm.

[0124] Thick coating of the positive electrode film can increase the loading of the positive electrode active material. In addition, the positive electrode film contains positive electrode additives, which can improve the flexibility of the electrode sheet and reduce cracking and detachment on the basis of thick coating.

[0125] According to some embodiments of this application, this application also provides a battery device including any of the battery cells described above.

[0126] According to some embodiments of this application, this application also provides an electrical device including the battery device described above.

[0127] Example

[0128] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0129] Example 1

[0130] A battery cell includes a positive electrode, a negative electrode, a separator, and an electrolyte.

[0131] The positive electrode includes a positive current collector and a positive electrode film layer disposed on one side of the positive current collector. The positive current collector is aluminum foil. The positive electrode film layer includes a positive active material, a positive conductive agent, and a positive additive. The positive active material is lithium nickel cobalt manganese oxide, the positive conductive agent is acetylene black, and the positive additive includes a first type of polymer and a second type of polymer. The first type of polymer is polyvinylidene fluoride with a molecular weight of 1.5 million, and the main chain of the second type of polymer is as shown in formula (I), with its anchoring group G being the group shown in formula (II). The mass ratio of lithium nickel cobalt manganese oxide, acetylene black, polyvinylidene fluoride, and the second type of polymer is 96.84:2:0.9:0.26.

[0132] The negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on one side of the negative current collector. The negative current collector is copper foil. The negative electrode film layer includes a negative electrode active material, a negative electrode conductive agent, a negative electrode binder, and a negative electrode dispersant. The negative electrode active material is artificial graphite, the negative electrode conductive agent is acetylene black, and the negative electrode binder is styrene-butadiene rubber (SBR). The mass ratio of artificial graphite, acetylene black, and styrene-butadiene rubber is 97:2:1.

[0133] The separator is a porous polyethylene polymer film.

[0134] The electrolyte consists of an electrolyte and a solvent. The electrolyte is LiPF6, the solvent system is EC:DEC = 1:1, and the concentration of the electrolyte is 1.0 mol / L.

[0135] Preparation of positive electrode sheet: Lithium nickel cobalt manganese oxide, acetylene black and positive electrode additives are added to N-methylpyrrolidone and stirred evenly to obtain positive electrode slurry; the positive electrode slurry is coated onto aluminum foil with a coating thickness of 110 μm, and then dried and cold pressed to obtain positive electrode sheet.

[0136] Preparation of negative electrode sheet: Add artificial graphite, acetylene black, binder and dispersant to deionized water, stir evenly to obtain negative electrode material, the solid content of negative electrode slurry is 45%; coat the negative electrode slurry onto copper foil, the coating thickness of negative electrode slurry is 98μm, and then dry and cold press to obtain negative electrode sheet.

[0137] The positive electrode, separator, and negative electrode are wound in sequence and according to size to form a cell, which is then encapsulated, injected with electrolyte, formed, and degassed to obtain a battery.

[0138] Example 2

[0139] Unlike Example 1, in this example, the second type of polymer accounts for 0.16% of the mass of the positive electrode film layer, while the remaining components and preparation methods are the same as in Example 1.

[0140] Example 3

[0141] Unlike Example 1, in this example, the second type of polymer accounts for 0.36% of the mass of the positive electrode film layer, while the remaining components and preparation methods are the same as in Example 1.

[0142] Example 4

[0143] Unlike Example 1, the anchoring group G in this example is the group shown in formula (III). The remaining components and preparation methods are the same as in Example 1.

[0144] Example 5

[0145] Unlike Example 1, the anchoring group G in this example is the group shown in formula (IV). The remaining components and preparation methods are the same as in Example 1.

[0146] Example 6

[0147] Unlike Example 1, the anchoring group G in this example is the group shown in formula (V). The remaining components and preparation methods are the same as in Example 1.

[0148] Example 7

[0149] Unlike Example 1, the anchoring group G in this example is the group shown in formula (VI). The remaining components and preparation methods are the same as in Example 1.

[0150] Example 8

[0151] Unlike Example 1, the anchoring group G in this example is the group shown in formula (VII). The remaining components and preparation methods are the same as in Example 1.

[0152] Comparative Example

[0153] Unlike Example 1, the mass ratio of lithium nickel cobalt manganese oxide, acetylene black, and polyvinylidene fluoride in this comparative example is 96.84:2:1.16, meaning that the cathode additive in this comparative example does not include the second type of polymer. The remaining components and preparation methods are the same as in Example 1.

[0154] Performance testing

[0155] Cohesion test: Take a defect-free positive electrode sheet and cut a sample 30mm wide and 100mm long with a blade; attach special double-sided tape to the steel plate, with the tape width 20mm and length 90mm; attach the cut electrode sample to the double-sided tape, with the test surface facing upwards; smoothly adhere a 20mm wide, 80mm longer than the sample length of low-tack green tape to the test surface and roll it three times in the same direction with a pressure roller; fix the end of the steel plate without the electrode sheet attached with the lower clamp of the tensile testing machine, fold the green tape with the cardboard attached upwards, fix it with the upper clamp, and pull at a tensile speed of 10mm / min until it breaks. The maximum value at break is the cohesion. The tensile testing machine is an electronic tensile testing machine, model LXG2-LLCS-0009.

[0156] Brittleness test: Take a defect-free positive electrode sheet and cut it longitudinally into samples with a length × width of 20cm × 2.5cm, with a sample size of 8 pieces. After pre-folding the samples, place them on the test platform and roll them once with a 2kg cylindrical roller. If light is transmitted, the brittleness test is performed once; if not, repeat the reverse folding and rolling. Observe the crease against the light to see if it is translucent or broken, record the actual number of folds, and take the average as the test result.

[0157] Film resistance: After drying, the positive electrode slurry (film layer) is cut into small round pieces with a diameter of 3mm from the left, center, and right sides of the positive electrode. The pieces are then placed at appropriate positions on the probe of an electrode resistance meter for testing. Once the reading stabilizes, the value is taken. Two positions are tested for each small round piece, and the average of six measurements is calculated; this average value is the resistance of the film layer on that electrode. The electrode resistance meter used is a HIOKI BT3563S.

[0158] 45℃ Cycle Capacity Retention: At 45℃, the battery is charged at a constant current of 1 / 3C to 3.65V, then charged at a constant voltage of 3.65V to a current of 0.05C, left to rest for 10 minutes, and then discharged at 1 / 3C to 2.5V. The resulting capacity is recorded as the initial capacity C0. The above steps are repeated, and the discharge capacity C of the battery after the nth cycle is recorded simultaneously. nThen, the battery capacity retention rate after each cycle is:

[0159] Pn = C n / C0×100%

[0160] During this test, the first loop corresponds to n=1, the second loop corresponds to n=2, ... the 100th loop corresponds to n=100.

[0161] Test Results

[0162] The test results of Examples 1-8 and the comparative examples are shown in Table 1.

[0163] Table 1 Test data for Examples 1-8 and comparative examples

[0164]

[0165]

[0166] As shown in Table 1, the positive electrode slurry in the embodiments of this application did not exhibit gelation after 48 hours of storage, while the positive electrode slurry in the comparative example without the addition of the second type of polymer showed severe gelation after 48 hours. This indicates that the positive electrode additive in this application can significantly improve the stability of the positive electrode slurry. The brittleness of the positive electrode sheet in the embodiments of this application is lower than that in the comparative example, indicating that the positive electrode additive in this application can improve the flexibility of the positive electrode sheet, making it less prone to cracking. Furthermore, the cohesive force of the positive electrode sheet in the embodiments of this application is higher than that in the comparative example, indicating that the bonding force between the positive electrode film layer and the current collector in this application is stronger, and the positive electrode film layer is less prone to problems such as shedding and powdering, thereby improving the cycle life of the battery.

[0167] Table 1 also shows that the film resistance of the positive electrode in this embodiment is as low as 0.51Ω and as high as 0.56Ω. Compared with the film resistance of 0.58Ω in the comparative example, the film resistance in this embodiment is reduced by 3.4%-12%. The capacity retention rate of the battery in this embodiment is as high as 91.7% and as low as 90.41%. Compared with the capacity retention rate of 90.11% in the comparative example, the capacity retention rate of the battery in this embodiment is increased by 0.3%-1.8%. This demonstrates that the additive in this embodiment can reduce film resistance, thereby improving the cycle life of the battery.

[0168] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, comprising a positive electrode sheet, wherein the positive electrode sheet comprises a positive electrode film layer, characterized in that, The positive electrode film layer includes a positive electrode additive, which includes a first type of polymer and a second type of polymer; The first type of polymers includes fluorinated olefin polymers; The second type of polymer includes an anchoring group G and a flexible segment. The anchoring group G includes at least one of carboxyl, sulfonic acid, phosphate, amide, and ester groups. The main chain of the flexible segment includes at least one of carbon-carbon single bonds, carbon-oxygen single bonds, ether bonds, ester bonds, and amide bonds.

2. The battery cell as described in claim 1, characterized in that, The flexible segment further includes at least one branch, which includes at least one of carbon chain, benzene ring, acid anhydride, polyether, and cyclic ether.

3. The battery cell as described in claim 1 or 2, characterized in that, The structural formula of the second type of polymer is shown in formula (I):

4. The battery cell according to any one of claims 1 to 3, characterized in that, The anchoring group G is a group represented by formula (II) or formula (III): Equation (II) Equation (III); Wherein, the C n It is an alkyl carbon chain, wherein R" includes hydrogen atoms, C1-C 12 Alkyl carbon chain, C1-C 12 Alkyl alcohols, C1-C 12 At least one of alkyl hydroxylamines.

5. The battery cell according to any one of claims 1 to 3, characterized in that, The anchoring group G is a group represented by formula (IV) or formula (V): Wherein, R" includes hydrogen atoms, C1-C 12 Alkyl carbon chain, C1-C 12 Alkyl alcohols, C1-C 12 At least one of alkyl hydroxylamines.

6. The battery cell according to any one of claims 1 to 3, characterized in that, The anchoring group G is a group represented by formula (VI) or formula (VII): Wherein, R3 and R5 are both C1-C 12 Alkylhydroxylamine, R4 includes a hydrogen atom, C1-C 12 Alkyl carbon chain, C1-C 12 At least one of alkyl alcohols.

7. The battery cell according to any one of claims 1 to 6, characterized in that, The polymer monomers of the first type of polymer include at least one of the compounds shown in formula (VIII) and formula (IX): Both R1 and R2 include hydrogen atoms and C1-C atoms. 12 Alkyl carbon chain, C1-C 12 The alkyl group contains at least one of the following: a benzene ring carbon chain, a polyether segment, or a polyoxyethylene ether-polyoxypropylene ether copolymer segment.

8. The battery cell according to any one of claims 1 to 7, characterized in that, The positive electrode additive accounts for 0.01%-3% of the mass of the positive electrode film.

9. The battery cell as described in claim 8, characterized in that, The first type of polymer accounts for 0.5%-1.1% of the mass of the positive electrode film; and / or, The second type of polymer accounts for 0.16%-0.36% of the mass of the positive electrode film.

10. The battery cell according to any one of claims 1 to 9, characterized in that, The coating thickness of the positive electrode film is 100μm-120μm.

11. A battery device, characterized in that, Includes the battery cell as described in any one of claims 1 to 10.

12. An electrical appliance, characterized in that, Includes the battery device as described in claim 11.

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