Polymer coating, electrode plate, isolating membrane, battery and electric device

Abstract

The invention discloses a polymer coating, an electrode plate, an isolating membrane, a battery and an electric device. The polymer coating comprises a binder and a liquid absorbent, the binder is prepared from at least one of polyvinylidene fluoride, a vinylidene fluoride-hexafluoropropylene copolymer, a vinylidene fluoride-trifluoroethylene copolymer, a vinylidene fluoride-tetrafluoroethylene copolymer, a vinylidene fluoride-trifluorochlor oethylene copolymer and a polyacrylic acid polymer; the liquid absorbing agent comprises at least one of a polyacrylate electrolyte, a polyether electrolyte, a polycarbonate electrolyte, a polycarboxylate electrolyte, a silicon-based electrolyte, polymercaptan, a maleic anhydride electrolyte and a polysulfate electrolyte. The polymer coating has relatively high viscosity and liquid absorption capability, and can improve the liquid retention capability and mechanical strength of the battery when being applied to the battery.

Description

Polymer coatings, electrode sheets, separators, batteries and electrical devices Technical Field

[0001] The present application relates to the field of new energy material technology, in particular to polymer coatings, electrode sheets, isolation membranes, batteries and electrical devices. Background Art

[0002] Batteries, as a new generation of green energy storage and conversion devices, have been widely used in fields such as portable electronic devices and electric vehicles. With the continuous development of new energy technologies, people have placed higher demands on battery performance. Among them, mechanical strength affects the battery's ability to withstand internal short circuits and impact shock. Therefore, high requirements are placed on how to improve the battery's mechanical strength. The above statements are intended only to provide background information related to this application and do not necessarily constitute prior art.

[0003] Summary of the Invention

[0004] In view of the above technical problems, the present application provides a polymer coating, an isolation film, a battery and an electrical device, which can improve the strength of the battery and enhance the battery's ability to resist internal short circuits and impact shocks.

[0005] In a first aspect, the present application provides a polymer coating comprising a binder and a liquid absorbent, wherein the binder comprises at least one of polyvinylidene fluoride, a vinylidene fluoride-hexafluoropropylene copolymer, a vinylidene fluoride-trifluoroethylene copolymer, a vinylidene fluoride-tetrafluoroethylene copolymer, a vinylidene fluoride-chlorotrifluoroethylene copolymer, and a polyacrylic acid polymer; and the liquid absorbent comprises at least one of a polyacrylate electrolyte, a polyether electrolyte, a polycarbonate electrolyte, a polycarboxylate electrolyte, a silicon-based electrolyte, a polythiol, a maleic anhydride electrolyte, and a polysulfate electrolyte. This polymer coating has high viscosity and liquid absorption capacity, and when used in a battery, it can improve the battery's liquid retention capacity and mechanical strength.

[0006] In some embodiments, the weight ratio of the binder to the liquid absorbing agent is 0.5:1-9:1, and can be optionally 1:1-4:1.

[0007] In some embodiments, the polymer coating includes a solvent, which includes one or more of NMP, acetone, and water. The selected solvent is a highly polar solvent that can improve the dissolving power of the polymer and improve the uniformity and stability of the formed polymer coating.

[0008] In some embodiments, the total mass concentration of the binder and the liquid absorbent in the polymer coating is 3%-15%. At this mass concentration, the viscosity of the polymer coating can be increased and the surface tension of the polymer coating can be reduced.

[0009] In a second aspect, the present application provides an application of a polymer coating in a battery. The polymer coating described in any of the above items can be applied to the structure of the battery as a functional coating, which can improve the battery's liquid retention capacity and mechanical strength.

[0010] In some embodiments, a battery includes an electrode sheet and a separator, and the application of the polymer coating as a functional coating on the electrode sheet and / or the separator can improve the mechanical strength of the electrode sheet and / or the separator.

[0011] In a third aspect, the present application provides an electrode sheet, wherein the electrode sheet includes a current collector and a reinforcement layer arranged on the current collector, the reinforcement layer includes a polymer coating, the polymer coating includes a binder and a liquid absorbent, the binder includes polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, and at least one of polyacrylic polymers; the liquid absorbent includes at least one of polyacrylate electrolytes, polyether electrolytes, polycarbonate electrolytes, polycarboxylate electrolytes, silicon-based electrolytes, polythiol, maleic anhydride electrolytes, and polysulfate electrolytes.

[0012] In the technical solution of the embodiments of this application, a reinforcement layer formed by a polymer coating is provided on the current collector of the electrode sheet. The polymers selected are materials with high viscosity and strong liquid absorption capacity. On the one hand, this can improve the bonding force and enhance the bonding strength between the electrode sheet and components such as the separator. On the other hand, the film layer formed by the selected polymer itself has excellent mechanical, thermal, and chemical stability, which can protect the electrode sheet and enhance its mechanical strength. Furthermore, the selected polymer has a certain liquid absorption capacity, which can reduce the risk of leakage in soft-pack batteries.

[0013] In some embodiments, the thickness of the strengthening layer of the electrode sheet is 0.5 μm-15 μm, and optionally 1 μm-5 μm. Within this selected thickness range, the strengthening layer can enhance the strength of the electrode sheet while minimizing the effect of the strengthening layer on the thickness of the electrode sheet. This allows the battery to have a higher energy density while improving mechanical strength.

[0014] In some embodiments, the electrode sheet further includes an active material layer located between the current collector and the reinforcement layer. This layer can coat the active material layer, reducing the likelihood of powder loss. Furthermore, it can enhance the self-supporting rigidity of the electrode sheet, thereby strengthening the electrode sheet.

[0015] In some embodiments, the electrode sheet includes a positive electrode sheet, which includes a positive electrode active material. The positive electrode active material includes one or more of lithium transition metal oxides and modified compounds thereof, olivine-structured lithium-containing phosphates and modified compounds thereof, and spinel-structured lithium-containing phosphates and modified compounds thereof. These materials can all be obtained through commercial channels.

[0016] In some embodiments, the electrode sheet comprises a negative electrode sheet, which includes a negative electrode active material. The negative electrode active material layer comprises a silicon-based material, and the silicon-based material comprises one or more of elemental silicon, silicon-oxygen compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The negative electrode active material can reduce negative electrode impedance, increase electrode capacity, reduce abnormal metal precipitation, and reduce dendrite formation. Covering the active material with a strengthening layer can also reduce volume expansion, thereby extending battery life.

[0017] In a fourth aspect, the present application provides an isolation membrane, wherein the isolation membrane includes a base membrane and a reinforcement layer disposed on the base membrane, the reinforcement layer including a polymer coating, the polymer coating including a binder and a liquid absorbent, the binder including at least one of polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, and polyacrylic acid polymers; and the liquid absorbent including at least one of polyacrylate electrolytes, polyether electrolytes, polycarbonate electrolytes, polycarboxylate electrolytes, silicon-based electrolytes, polythiol, maleic anhydride electrolytes, and polysulfate electrolytes. The isolation membrane is provided with a reinforcement layer formed by the polymer coating, and the polymer selected is a material with high viscosity and strong liquid absorption capacity. On the one hand, it can improve the bonding force between the isolation membrane and components such as electrode sheets and enhance the bonding strength; on the other hand, the film layer formed by the selected polymer itself has excellent mechanical stability, thermal stability, and chemical stability, which can protect the isolation membrane, enhance the mechanical strength of the isolation membrane, make the isolation membrane less likely to be punctured, and reduce the risk of electrode sheet short circuit. Furthermore, the selected polymer has a certain liquid absorption capacity, which can reduce the leakage risk of the soft-pack battery.

[0018] In some embodiments, the thickness of the separator's reinforcement layer is 0.5 μm to 15 μm, optionally 1 μm to 5 μm. Within this selected thickness range, the separator's strength is enhanced while minimizing the effect of the reinforcement layer on the separator's thickness. This allows the battery to have a higher energy density while improving mechanical strength.

[0019] In some embodiments, the separator is made of one or more materials selected from polyethylene, polypropylene, non-woven fabric, and polyvinylidene fluoride. The porosity of polyethylene, polypropylene, non-woven fabric, and polyvinylidene fluoride facilitates ion transport between the positive and negative electrodes and provides the separator with sufficient air permeability.

[0020] In a fifth aspect, the present application provides a battery comprising any of the aforementioned electrode sheets or any of the aforementioned separators. The battery provided herein may include a strengthening layer provided on the positive and / or negative electrode sheets, or on the separator. The strengthening layer can enhance the mechanical strength of the battery, reduce the risk of internal short circuits, improve its resistance to impact and shock, and extend its service life. It can also improve the battery's ability to retain liquid.

[0021] In some embodiments, a battery comprises a stacked positive electrode sheet, a separator, and a negative electrode sheet; a strengthening layer is provided on the side of the negative electrode sheet facing the separator. In this embodiment, the strengthening layer can be provided only on the side of the negative electrode sheet facing the separator. This layer can form a protective layer on the surface of the negative electrode sheet, thereby increasing its strength and reducing the risk of short circuits between the positive and negative electrodes. It can also reduce the volume expansion rate of the negative electrode while increasing energy density.

[0022] In some embodiments, the battery further includes an electrolyte, including a gel electrolyte. By using a gel electrolyte, the polymer coating on the electrode sheet or separator absorbs and swells, and then forms a condensed state when stimulated by light, heat, electricity, or other factors. This condensed state further enhances the battery's liquid retention capacity and reduces the risk of leakage.

[0023] In some embodiments, the electrolyte includes monomers and initiators. The monomers include one or more of methyl methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, n-butyl methacrylate, butyl acrylate, n-octyl methacrylate, n-octyl acrylate, vinyl acetate, vinylene carbonate, vinyl ethylene carbonate, triethylene glycol dimethacrylate, diethylene glycol dimethacrylate, ethylene glycol dimethacrylate, allyl methacrylate, divinylbenzene, polyvinyl alcohol, and styrene. The initiator includes one or more of persulfate, azo initiator, and organic peroxide initiator. The addition of the monomers and initiator can combine with the liquid electrolyte to form a gel electrolyte. Specifically, the monomers and liquid electrolyte produce a gelation reaction through the initiator to form a gel electrolyte, thereby improving the stability of the electrolyte.

[0024] In a sixth aspect, the present application provides an electrical device comprising any of the above batteries. Since the device of the present application comprises the battery provided by the present application, it has at least the same advantages as the battery.

[0025] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0027] FIG1 is a schematic structural diagram of a vehicle according to one or more embodiments;

[0028] FIG2 is a schematic diagram of an exploded structure of a battery according to one or more embodiments;

[0029] FIG3 is a schematic diagram of an exploded structure of a battery cell according to one or more embodiments;

[0030] FIG4 is a schematic structural diagram of an electrode sheet according to one or more embodiments;

[0031] FIG5 is a schematic structural diagram of an electrode sheet according to one or more embodiments;

[0032] FIG6 is a schematic structural diagram of an isolation membrane according to one or more embodiments;

[0033] FIG. 7 is a schematic structural diagram of an electrode assembly according to one or more embodiments. DETAILED DESCRIPTION

[0034] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0036] In the description of the embodiments of the present application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two), similarly, "multiple groups" refers to more than two (including two), and "multiple pieces" refers to more than two (including two), unless otherwise clearly and specifically defined.

[0037] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0038] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0039] With the widespread use of electrical devices, people are increasingly demanding higher performance, especially in terms of battery stability and capacity. They expect batteries to have excellent overall performance in all aspects. A battery's mechanical properties can affect its overall performance. Insufficient mechanical strength can reduce the battery's ability to withstand shock and vibration, leading to significant damage after an impact. Insufficient mechanical strength of the battery's electrodes and separators can easily damage the battery, causing short circuits and potentially harming the system. Consequently, there are high demands for improving the battery's mechanical strength.

[0040] In order to solve the above technical problems, this application starts from the various components in the battery, improves the strength of the components themselves, and at the same time strengthens the bonding force between the components to improve the mechanical strength of the battery as a whole; thereby improving the ability to resist internal short circuits and impact shocks.

[0041] The electrode sheets, separators, and polymer coatings disclosed in the embodiments of this application can be used in batteries. The batteries disclosed in the embodiments of this application can be used in electrical devices that use batteries as power sources or in various energy storage systems that use batteries as energy storage elements. Electrical devices can include, but are not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, and the like.

[0042] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electric device according to one or more embodiments.

[0043] Please refer to Figure 1, which is a schematic structural diagram of a vehicle according to one or more embodiments. The vehicle 1000 can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000, and the battery 100 can be provided at the bottom, head or tail of the vehicle 1000. The battery 100 can be used to power the vehicle 1000. For example, the battery 100 can serve as an operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to power the motor 300, for example, for starting, navigating and driving the vehicle 1000.

[0044] In some embodiments of the present application, the battery 100 can serve not only as an operating power source for the vehicle 1000, but also as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0045] Please refer to Figure 2, which is a schematic diagram of an exploded structure of a battery according to one or more embodiments. Battery 100 includes a housing 10 and battery cells 20, with battery cells 20 housed within housing 10. Housing 10 provides storage space for battery cells 20 and can have various structures. In some embodiments, housing 10 can include a first portion 11 and a second portion 12, which overlap each other and together define a storage space for battery cells 20. Second portion 12 can be a hollow structure with one end open. First portion 11 can be a plate-like structure, overlapping the open side of second portion 12, so that the first and second portions 11 and 12 together define a storage space. Alternatively, first portion 11 and second portion 12 can each be a hollow structure with one end open, with the open side of first portion 11 overlapping the open side of second portion 12. Housing 10 formed by first portion 11 and second portion 12 can have various shapes, such as a cylinder or a rectangular parallelepiped.

[0046] In the battery 100, there may be multiple battery cells 20, and the multiple battery cells 20 may be connected in series, in parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections among the multiple battery cells 20. The multiple battery cells 20 may be directly connected in series, in parallel, or in a hybrid connection, and then the entire battery cell 20 may be housed within the housing 10. Alternatively, the battery 100 may be constructed by first connecting multiple battery cells 20 in series, in parallel, or in a hybrid connection to form a battery module, which is then connected in series, in parallel, or in a hybrid connection to form a complete battery module, and then housed within the housing 10. The battery 100 may also include other structures, such as a busbar assembly for electrically connecting the multiple battery cells 20.

[0047] Each battery cell 20 may be a secondary battery or a primary battery, and may also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 20 may be cylindrical, flat, rectangular, or in other shapes.

[0048] Please refer to Figure 3, which shows an exploded view of a battery cell according to one or more embodiments. A battery cell 20 is the smallest unit of a battery. As shown in Figure 3, a battery cell 20 includes an end cap 21, a housing 22, an electrode assembly 23, and other functional components.

[0049] The end cap 21 is a component that covers the opening of the housing 22 to isolate the internal environment of the battery cell 20 from the external environment. The shape of the end cap 21 can be adapted to the shape of the housing 22 to fit the housing 22. Optionally, the end cap 21 can be made of a material with a certain hardness and strength (such as an aluminum alloy). This prevents the end cap 21 from deforming when subjected to compression or collision, thereby providing the battery cell 20 with greater structural strength and improved safety. The end cap 21 can be provided with functional components such as electrode terminals 21a. The electrode terminals 21a can be used to electrically connect to the electrode assembly 23 for inputting or outputting electrical energy from the battery cell 20. In some embodiments, the end cap 21 can also be provided with a pressure relief mechanism for relieving internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold. The end cap 21 can also be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this embodiment of the present application does not impose any particular limitations on this. In some embodiments, an insulating member may be provided inside the end cap 21 to isolate the electrical connection components in the housing 22 from the end cap 21 to reduce the risk of short circuit. For example, the insulating member may be made of plastic, rubber, or the like.

[0050] The housing 22 is a component that cooperates with the end cap 21 to form the internal environment of the battery cell 20. This internal environment can be used to accommodate the electrode assembly 23, electrolyte, and other components. The housing 22 and end cap 21 can be separate components. An opening can be provided in the housing 22, and the end cap 21 is placed over the opening to form the internal environment of the battery cell 20. Alternatively, the end cap 21 and housing 22 can be integrated. Specifically, the end cap 21 and housing 22 can form a common connection surface before other components are inserted into the housing. When the interior of the housing 22 needs to be enclosed, the end cap 21 is placed over the housing 22. The housing 22 can have a variety of shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, or a hexagonal prism. Specifically, the shape of the housing 22 can be determined based on the specific shape and size of the electrode assembly 23. The housing 22 can be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this embodiment of the present application does not impose any particular limitations on this.

[0051] The electrode assembly 23 is a component in the battery cell 100 where electrochemical reactions occur. One or more electrode assemblies 23 may be contained in the housing 22. The electrode assembly 23 is mainly formed by winding or stacking positive and negative electrode sheets, and a separator is usually provided between the positive and negative electrode sheets. The parts of the positive and negative electrode sheets with active materials constitute the main body of the electrode assembly, and the parts of the positive and negative electrode sheets without active materials each constitute a tab 23a. The positive and negative electrode tabs may be located together at one end of the main body or respectively at both ends of the main body. During the charge and discharge process of the battery, the positive active material and the negative active material react with the electrolyte, and the tabs 23a connect the electrode terminals to form a current loop.

[0052] The present application provides a polymer coating, which includes a binder and a liquid absorbent, wherein the binder includes at least one of polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, and polyacrylic acid polymer; and the liquid absorbent includes at least one of polyacrylate electrolytes, polyether electrolytes, polycarbonate electrolytes, polycarboxylate electrolytes, silicon-based electrolytes, polythiol, maleic anhydride electrolytes, and polysulfate electrolytes.

[0053] This polymer coating has excellent firmness and adhesion, and can be used as a coating for electrode plates and / or separators, which can improve the mechanical strength of positive plates, negative plates, or separators. Furthermore, this polymer coating helps absorb and retain electrolytes. When used in soft-pack batteries, this polymer coating can reduce the risk of electrolyte leakage. When used on positive plates, negative plates, or separators, it improves the strength of the positive plates, negative plates, or separators, increasing the strength of the battery cells, compensating for the insufficient strength of the soft-pack battery shell itself, and improving the overall mechanical strength of the soft-pack battery.

[0054] In some embodiments, polymer coating can include vinylidene fluoride-hexafluoropropylene copolymer and polycarbonate electrolyte.Or polymer coating can include vinylidene fluoride-chlorotrifluoroethylene copolymer and polyacrylate electrolyte.Or polymer coating can include vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer and polyacrylate electrolyte.Or polymer coating can include vinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer and polyacrylate electrolyte and polycarboxylate electrolyte etc.More specifically, polymer coating can include vinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP) and polycarbonate glycol.Or polymer coating can include vinylidene fluoride-trifluoroethylene copolymer (PVDF-TrFE) and polymethacrylate.

[0055] In some embodiments, the weight ratio of the binder to the liquid absorbing agent is 0.5:1-9:1, optionally 1:1-4:1. Specifically, it can be 0.5:1, 0.9:1, 1:1, 1.1:1, 1.5:1, 1.8:1, 2.2:1, 2.7:1, 3.0:1, 3.3:1, 3.6:1, 3.9:1, 4.0:1, 4.1:1, 4.5:1, 5.0:1, 5.6:1, 6.0:1, 6.5:1, 7.1:1, 7.5:1, 8.3:1, 9:1, etc. The above-mentioned ranges may also be used, for example, 0.5:1-0.9:1, 0.9:1-1.1:1, 1.1:1-3.9:1, 1.5:1-3.3:1, 1.8:1-3.0:1, 1.5:1-2.7:1, 2.2:1-2.7:1, 2.7:1-3.9:1, 3.0:1-3.6:1, 4.5:1-6.3:1, 5.0:1-8.0:1, 5.5:1-7.7:1, 7.2:1-8.7:1, 6.0:1-3.9:1, etc. The polymer coating includes a binder and a liquid absorbent in this weight ratio, which can better achieve excellent firmness, adhesion and liquid retention. When used as a coating for an electrode plate and / or a separator, it can improve the mechanical strength of the positive electrode plate, the negative electrode plate or the separator. This will improve the battery's liquid retention capacity and mechanical strength.

[0056] In some embodiments, the polymer coating includes a solvent, and the solvent includes one or more of nitrogen-methyl pyrrolidone, acetone, and water. First, the polymer can be dissolved in highly polar solutions, such as nitrogen-methyl pyrrolidone, acetone, and water, at relatively low temperatures. The high solubility of nitrogen-methyl pyrrolidone, acetone, and water for the polymer improves the uniformity, adhesion, and storage stability of the resulting polymer coating. Furthermore, nitrogen-methyl pyrrolidone, acetone, and water do not chemically react with the polymer components provided in the above-described embodiments, thereby improving the stability of the polymer coating. Furthermore, the coating has requirements for the solvent's evaporation rate. If the solvent evaporates too quickly, the coating will neither level nor sufficiently wet the electrode sheet or isolation membrane, resulting in poor adhesion and cohesion. A solvent that evaporates too quickly can also cause water vapor on the surface of the electrode sheet or isolation membrane to condense due to cooling, causing the coating to turn white. If the solvent evaporates too slowly, not only will the drying time be delayed, but the coating will also sag and become very thin. Strongly polar solvents like NMP, acetone, and water have a moderate evaporation rate, neither too fast nor too slow, allowing for better control of coating fluidity. Furthermore, as highly polar solvents, NMP, acetone, and water have low resistivity, minimizing the impact on ion permeability of the electrode or separator.

[0057] In some embodiments, the total mass concentration of the binder and the liquid absorbing agent in the polymer coating is 3%-15%. That is, the mass concentration of the polymer (including the binder and the liquid absorbing agent) in the polymer coating is 3%-15%. Specifically, it can be 3.0%, 3.2%, 4.5%, 5.3%, 8.7%, 10.4%, 11.6%, 13.4%, 14.7%, or 15%. It can also be the range formed above, for example, it can be 3.0%-5.3%, 4.5%-8.7%, 5.3%-10.4%, 8.7%-10.4%, 5.3%-8.7%, 10.4%-13.4%, 11.6%-14.7%, or 13.4%-15%. The content of the polymer can affect the cohesiveness and surface tension of the polymer coating. The appropriate mass concentration can improve the cohesiveness of the polymer coating and reduce the surface tension of the polymer coating. Among them, if the polymer mass concentration is too large, the surface tension of the polymer coating will be greater, and if the polymer mass concentration is too small, the cohesiveness function required by the polymer coating cannot be achieved. By setting the polymer mass concentration to 3%-15%, the effect of surface tension on the polymer coating can be reduced on the basis of improving the adhesion of the polymer coating.

[0058] The polymer coating disclosed in the embodiments of the present application can be applied to the battery field as a coating for the electrode sheets and separators of the battery to enhance the performance of the electrode sheets and separators.

[0059] Please refer to FIG. 4 , which is a schematic structural diagram of an electrode sheet according to one or more embodiments.

[0060] According to some embodiments of the present application, an electrode sheet 30 is provided, which includes a current collector 31 and a reinforcement layer 32 arranged on the current collector 31. The reinforcement layer 32 includes a polymer coating, and the polymer coating includes a binder and a liquid absorbent. The binder includes at least one of polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, and polyacrylic acid polymer; the liquid absorbent includes at least one of polyacrylate electrolytes, polyether electrolytes, polycarbonate electrolytes, polycarboxylate electrolytes, silicon-based electrolytes, polythiol, maleic anhydride electrolytes, and polysulfate electrolytes.

[0061] In this embodiment, a reinforcement layer 32 is provided on the current collector 31. The reinforcement layer 32 includes a polymer coating. The selected polymer is a highly viscous material. On the one hand, its viscosity can improve the bonding force between the electrode sheet 30 and components such as the isolation membrane, and enhance the bonding strength between the components; on the other hand, the film layer formed by the selected polymer itself has excellent mechanical stability, thermal stability, and chemical stability, which can protect the electrode sheet 30 and enhance the mechanical strength of the electrode sheet 30. Specifically, when the polymer coating is formed, a portion of the polymer coating solution can penetrate into the surface pores of the electrode sheet, and then heated and compacted, which will enhance the rigidity of the electrode sheet like tree roots binding the soil. Furthermore, the selected polymer has a certain liquid absorption capacity, which can reduce the risk of leakage of soft-pack batteries. Therefore, the introduction of the polymer coating can improve battery performance in many aspects.

[0062] Specifically, the polymer coating includes a binder and a liquid absorbent. The binder includes at least one of polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, and polyacrylic acid polymers; the liquid absorbent includes at least one of polyacrylate electrolytes, polyether electrolytes, polycarbonate electrolytes, polycarboxylate electrolytes, silicon-based electrolytes, polythiol, maleic anhydride electrolytes, and polysulfate electrolytes. The binder or liquid absorbent can be a single polymer, a mixture of any two polymers, or a mixture of three or more polymers. For example, the polymer coating can include vinylidene fluoride-hexafluoropropylene copolymer and a polycarbonate electrolyte. Or the polymer coating can include vinylidene fluoride-chlorotrifluoroethylene copolymer and a polyacrylate electrolyte. Or the polymer coating can include vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, and a polyacrylate electrolyte. Or the polymer coating can include vinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, a polyacrylate electrolyte, and a polycarboxylate electrolyte. More specifically, the polymer coating may include a vinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP) and polycarbonate diol. Alternatively, the polymer coating may include a vinylidene fluoride-trifluoroethylene copolymer (PVDF-TrFE) and polymethacrylate. The polymer mixing method is not limited here.

[0063] In some embodiments, the thickness of the strengthening layer 32 of the electrode sheet 30 is 0.5 μm-15 μm. Optionally, the thickness of the strengthening layer 32 is 1.0 μm-5.0 μm. Specifically, the thickness may be 0.96 μm, 3.0 μm, 5.3 μm, 8.2 μm, 10.1 μm, 11.5 μm, 13.6 μm, 14.8 μm; or combinations thereof, such as 0.96-3.0 μm, 1.30-3.2 μm, 4.59 μm-10.1 μm, 5.67 μm-11.4 μm, 8.32 μm-12.5 μm, 9.14 μm-14.9 μm, 10.8 μm-13.8 μm, and 12.3 μm-13.9 μm. If the strengthening layer 32 is too thin, it will not achieve the desired strengthening effect. If the strengthening layer 32 is too thick, the total thickness of the electrode sheet 30 will increase, affecting the energy density of the battery. By setting the thickness of the strengthening layer 32 to 0.5μm-15μm, the effect of the strengthening layer 32 on the thickness of the electrode sheet 30 can be minimized while enhancing the performance of the electrode sheet 30. This allows the battery to have a higher energy density while improving mechanical strength.

[0064] Please refer to FIG. 5 , which is a schematic structural diagram of an electrode sheet according to one or more embodiments.

[0065] In some embodiments, the electrode sheet 30 further includes an active material layer 34, which is located between the current collector 31 and the reinforcement layer 32. The active material layer 34 includes a positive electrode active material or a negative electrode active material. The reinforcement layer 32 can inhibit the expansion of the active material and reduce the expansion rate.

[0066] The electrode sheet 30 may be a positive electrode sheet, which includes a positive electrode active material. The electrode sheet 30 may be used in lithium batteries, and the positive electrode active material may be one or more of lithium transition metal oxides and their modified compounds, olivine-structured lithium-containing phosphates and their modified compounds, and spinel-structured lithium-containing phosphates and their modified compounds. Examples of lithium transition metal oxides may include, but are not limited to, one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their modified compounds. Examples of olivine-structured lithium-containing phosphates may include, but are not limited to, one or more of lithium iron phosphate, lithium iron phosphate and carbon composites, lithium manganese phosphate, lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, lithium iron manganese phosphate and carbon composites, and their modified compounds. These materials are commercially available. The electrode sheet 30 may be used in sodium batteries, and the positive electrode active material may include, but is not limited to, at least one of sodium transition metal oxides, polyanionic compounds, and Prussian blue compounds. In the sodium transition metal oxide, the transition metal may be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce. Sodium transition metal oxide is, for example, Na x MO2, wherein M is one or more of Ti, V, Mn, Co, Ni, Fe, Cr and Cu, 0<x≤1. The polyanionic compound can be a compound with sodium ions, transition metal ions and tetrahedral (YO4) n- A class of compounds with anionic units. The transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce; Y can be at least one of P, S and Si; n represents (YO4) n- The polyanionic compound can also be a compound with sodium ions, transition metal ions, tetrahedral (YO4) n- A class of compounds containing anion units and halogen anions. The transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; Y can be at least one of P, S, and Si, and n represents (YO4) n- The halogen can be at least one of F, Cl and Br. The polyanionic compound can also be a compound with sodium ions, tetrahedral (YO4) n- Anion unit, polyhedron unit (ZO y )m+ and an optional halogen anion. Y can be at least one of P, S and Si, and n represents (YO4) n- valence state; Z represents a transition metal, which may be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce, and m represents (ZO y ) m+ The halogen can be at least one of F, Cl and Br. Examples of polyanionic compounds are NaFePO4, Na3V2(PO4)3, NaM'PO4F (M' is one or more of V, Fe, Mn and Ni) and Na3(VO y )2(PO4)2F 3-2y (0≤y≤1) at least one. Prussian blue compounds can be sodium ions, transition metal ions and cyanide ions (CN - ) compounds. The transition metal may be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce. Prussian blue compounds are, for example, Na a Me b Me' c (CN)6, wherein Me and Me' are each independently at least one of Ni, Cu, Fe, Mn, Co and Zn, 0<a≤2, 0<b<1, 0<c<1. These materials are commercially available.

[0067] The electrode sheet 30 can be a negative electrode sheet, which includes a negative electrode active material. The negative electrode active material can be one or more of a silicon-based material, a silicon-carbon material, a carbon material, and a selenium-based material. Specifically, it includes one or more of artificial graphite, natural graphite, hard carbon, soft carbon, a silicon-based material, and a tin-based material. The silicon-based material can be selected from one or more of elemental silicon, silicon oxides (such as silicon monoxide), silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The selenium-based material can be selected from one or more of elemental selenium, selenium oxide, and selenium alloys. These materials can all be obtained through commercial channels. The negative electrode active material can reduce the impedance of the negative electrode, increase the electrode capacity, reduce the abnormal precipitation of metals, and reduce dendrites.

[0068] The electrode sheet 30 may further include a binder, a conductive agent, and other optional additives.

[0069] As an example, the conductive agent may be one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, Super P (SP), graphene, and carbon nanofibers.

[0070] As an example, the binder can be one or more of styrene-butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA) and polyvinyl butyral (PVB).

[0071] As an example, other optional auxiliary agents may be thickening and dispersing agents (such as sodium carboxymethyl cellulose CMC-Na), and PTC thermistor materials.

[0072] In this embodiment, by providing a reinforcement layer 32 on the surface of the active material layer 34, a portion of the polymer coating solution can penetrate the pores on the surface of the electrode sheet during the formation of the polymer coating. This dendrite-like structure binds the active layer, much like tree roots bind soil, enhancing the self-supporting rigidity of the electrode sheet. This also improves the bonding strength between the active material layer 34 and the current collector 31, reducing the probability of powder loss.

[0073] Please refer to FIG. 6 , which is a schematic structural diagram of an isolation membrane according to one or more embodiments.

[0074] According to some embodiments of the present application, the present application also provides an isolation film 40, which includes a base film 41 and a reinforcement layer 33 arranged on the base film 41, the reinforcement layer 33 includes a polymer coating, the polymer coating includes a binder and a liquid absorbent, the binder includes polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-trifluorochloroethylene copolymer, and polyacrylic acid polymer at least one; the liquid absorbent includes at least one of polyacrylate electrolytes, polyether electrolytes, polycarbonate electrolytes, polycarboxylate electrolytes, silicon-based electrolytes, polythiol, maleic anhydride electrolytes, and polysulfate electrolytes.

[0075] The separator 40 is positioned between the positive and negative electrodes, acting as an insulating layer to effectively prevent contact between the two electrodes and cause internal short circuits while allowing electrolyte ions to pass through. The performance of the separator 40 directly impacts the mechanical strength and safety of the battery. However, during the winding or stacking process, microcracks may form in the positive and negative electrodes, leading to detachment of the active material layer. This can lead to uneven lithium deposition and, in turn, the formation of dendrites. These dendrites can pierce the separator 40 between the positive and negative electrodes, causing a short circuit and battery failure. A strengthening layer 33 formed from a polymer coating is applied to the separator 40. The polymer is selected to have a high viscosity. This not only improves the bonding strength between the separator and the electrode sheets, but also enhances the bonding strength. Furthermore, the film layer formed by the selected polymer has excellent mechanical, thermal, and chemical stability, protecting the separator and enhancing its mechanical strength, making it less susceptible to puncture and reducing the risk of electrode short circuits. Furthermore, the selected polymer exhibits a certain degree of liquid absorption, which can reduce the risk of leakage in soft-pack batteries.

[0076] In some embodiments, the thickness of the strengthening layer 33 is 0.5 μm-15 μm, optionally 1 μm-5 μm. Specifically, the thickness may be 0.65 μm, 2.7 μm, 5.0 μm, 7.9 μm, 9.7 μm, 11.2 μm, 13.3 μm, 14.5 μm, or combinations thereof, such as 0.53-3.1 μm, 1.27-2.9 μm, 4.55 μm-9.3 μm, 5.45 μm-11.1 μm, 8.29 μm-12.2 μm, 9.0 μm-14.2 μm, 10.1 μm-13.2 μm, and 12.1 μm-13.3 μm. If the strengthening layer 33 is too thin, the strengthening effect will not be achieved. If the strengthening layer 33 is too thick, the total thickness of the separator 40 will increase, affecting the energy density of the battery. By setting the thickness of the strengthening layer to 0.5 μm-15 μm, the effect of the strengthening layer 33 on the thickness of the isolation membrane 40 can be minimized while strengthening the performance of the isolation membrane 40, so that the battery can have a higher energy density while improving the mechanical strength.

[0077] In some embodiments, the separator 40 is made of one or more materials selected from polyethylene, polypropylene, non-woven fabric, and polyvinylidene fluoride. The porosity of polyethylene, polypropylene, non-woven fabric, and polyvinylidene fluoride is sufficient to facilitate ion transport between the positive and negative electrodes, while also providing a certain degree of air permeability for the separator 40.

[0078] According to some embodiments of the present application, the present application further provides a battery 100, comprising any of the above-mentioned electrode sheets 30, or the above-mentioned separator 40. The present application may provide a strengthening layer 32 on the electrode sheet 30, or a strengthening layer 33 on the separator 40. The strengthening layer can improve the strength of the electrode sheet 30 or the separator 40. By connecting the high-strength electrode sheet 30 or the high-strength separator 40 together through heating and compaction, the mechanical strength of the battery 100 can be improved.

[0079] Please refer to FIG. 7 , which is a schematic structural diagram of an electrode assembly according to one or more embodiments.

[0080] In some embodiments, the battery 100 includes a stacked positive electrode sheet 301, a separator 40, and a negative electrode sheet 302; a strengthening layer 32 is provided on the side of the negative electrode sheet 302 facing the separator 40. The separator 40 is used to isolate the adjacent positive electrode sheets 301 and negative electrode sheets 302. The battery 100 provided in this application can have a strengthening layer 32 provided on the positive electrode sheet 301, a strengthening layer 32 provided on the negative electrode sheet 302, or a strengthening layer 32 provided on both the positive electrode sheet 301 and the negative electrode sheet 302. In addition, a strengthening layer 33 can also be provided on the separator 40. The strengthening layer can improve the inherent strength of the positive electrode sheet 301, the negative electrode sheet 302, or the separator 40, and increase the adhesion between the positive electrode sheet 301, the negative electrode sheet 302, and the separator 40, thereby improving the mechanical strength of the battery and extending the battery life.

[0081] In this embodiment, a strengthening layer 32 can be provided on the side of the negative electrode sheet 302 facing the separator 40 to form a protective layer on the surface of the negative electrode sheet 302, thereby increasing the strength of the negative electrode sheet and reducing the risk of short circuit between the positive and negative electrodes of the battery; at the same time, the energy density can be increased.

[0082] In some embodiments, the battery 100 further includes an electrolyte. The electrolyte acts as a conductive ion between the positive electrode and the negative electrode. The electrolyte may include an electrolyte salt and a solvent. As an example, the electrolyte salt may be selected from one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalatoborate (LiDFOB), lithium dioxalatoborate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorobis(oxalatophosphate) (LiDFOP) and lithium tetrafluorooxalatophosphate (LiTFOP). It can also be one or more of NaPF6 (sodium hexafluorophosphate), NaDFOB (sodium difluorooxalatoborate), NaBF4 (sodium tetrafluoroborate), NaBOB (sodium bisoxalatoborate), NaClO4 (sodium perchlorate), NaAsF6 (sodium hexafluoroarsenate), NaFSI (sodium bis(fluorosulfonyl)imide), NaOTf (sodium trifluoromethylsulfonate) and NaTFSI (sodium bis(trifluoromethylsulfonyl)imide). As an example, the solvent can be selected from one or more of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS) and diethyl sulfone (ESE).

[0083] In some embodiments, the electrolyte comprises a liquid electrolyte, wherein the liquid electrolyte is characterized by stable and reliable electrochemical performance, but generally has problems such as poor safety, insufficient battery hardness, and easy deformation.

[0084] In some embodiments, the electrolyte comprises a gel electrolyte. Gel electrolytes not only possess the high ionic conductivity of liquid electrolytes but also offer excellent processing properties. Gel electrolytes immobilize fluidic solvent molecules within a polymer gel skeleton, maintaining stability when heated at the interface between the positive and negative electrodes, thereby reducing the risk of electrolyte leakage. By using a gel electrolyte, the polymer coating on the electrode sheet or separator absorbs and swells, then forms a condensed state when stimulated by light, heat, electricity, or other factors. This condensed state further enhances the battery's fluid retention and reduces the risk of leakage.

[0085] In some embodiments, the electrolyte includes monomers and initiators. The monomers include one or more of methyl methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, n-butyl methacrylate, butyl acrylate, n-octyl methacrylate, n-octyl acrylate, vinyl acetate, vinylene carbonate, vinyl ethylene carbonate, triethylene glycol dimethacrylate, diethylene glycol dimethacrylate, ethylene glycol dimethacrylate, allyl methacrylate, divinylbenzene, polyvinyl alcohol, and styrene. The initiator includes one or more of persulfate, azo initiator, and organic peroxide initiator. A gel electrolyte is made from a liquid electrolyte, monomers, and initiator. The added monomers are soluble in the liquid electrolyte. The monomers and liquid electrolyte undergo a gelation reaction via the initiator to form the gel electrolyte.

[0086] Specifically, the addition of monomers and initiators, under conditions such as light, heat, and electricity, triggers a gelation reaction, producing a gel electrolyte. The gel electrolyte has strong liquid absorption and retention capabilities, reducing electrolyte leakage.

[0087] The present application provides an electrical device, comprising any one of the above batteries 100. Since the device of the present application comprises the battery provided by the present application, it has at least the same advantages as the battery.

[0088] In the above embodiments, the electrode sheet provided by the present application is provided with a strengthening layer on the current collector. The polymer coating contained in the strengthening layer has high adhesion, which can improve the strength of the electrode sheet; and a strengthening layer can also be provided on the separator. The polymer coating contained in the strengthening layer has high adhesion, which can improve the strength of the separator and reduce the risk of internal short circuits in the battery; the electrode sheet containing the polymer coating is bonded to the separator, or the electrode sheet is bonded to the separator containing the polymer coating, which can improve the mechanical strength and safety performance of the battery. Furthermore, the polymer coating helps the electrolyte to absorb and retain liquid. When used in a battery, it can reduce the risk of battery electrolyte leakage and improve the safety performance of the battery.

[0089] The beneficial effects of the present application are further illustrated below with reference to the examples.

[0090] In order to make the technical problems, technical solutions and beneficial effects solved by the embodiments of the present application clearer, the following will be further described in detail with reference to the embodiments and drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present application and its applications. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0091] Example 1

[0092] Separately, negative and positive electrodes were prepared. Graphite was used as the active material for the negative electrode, while LiNi8Co1Mn1O4 was used as the active material for the positive electrode. A polymer coating with a thickness of 1μm was applied to both the positive and negative electrodes. A polyethylene separator was also prepared, and a liquid electrolyte was used. The positive, separator, and negative electrodes were stacked, and the electrolyte was injected to form a battery. Multiple charge and discharge cycles were performed, and the battery was tested for compression deformation under a force of 3000N, self-discharge voltage drop, and fluid loss after the case was punctured. The data are shown in Table 1.

[0093] Examples 2-4

[0094] The specific preparation method was essentially the same as in Example 1, except that the polymer coating thicknesses were 3 μm, 5 μm, 15 μm, and 20 μm, respectively. A battery was constructed by stacking the positive electrode sheet, separator, negative electrode sheet, and liquid electrolyte. Multiple charge and discharge cycles were performed, and the battery was tested for extrusion deformation under a force of 3000 N, self-discharge voltage drop, fluid loss after casing puncture, and energy density. The data are shown in Table 1.

[0095] Examples 6-9

[0096] The specific preparation method was essentially the same as that in Example 2, except that the ratios of binder to liquid absorbent in the polymer coating were 0.5:1, 1:1, 4:1, and 9:1, respectively. A battery was constructed by stacking the positive electrode sheet, separator, negative electrode sheet, and liquid electrolyte. Multiple charge and discharge cycles were performed, and the battery was tested for extrusion deformation under a force of 3000 N, self-discharge voltage drop, liquid loss after casing puncture, and energy density. The data are shown in Table 1.

[0097] Example 10

[0098] A negative electrode sheet and a positive electrode sheet were prepared separately. Graphite was used as the active material for the negative electrode, and LiNi8Co1Mn1O4 was used as the active material for the positive electrode. A polyethylene separator was prepared, and a 3μm-thick polymer coating was formed on the separator. A liquid electrolyte was used. The positive electrode sheet, separator, negative electrode sheet, and liquid electrolyte were stacked to form a battery. Multiple charge and discharge cycles were performed, and the battery was tested for compression deformation under a force of 3000N, self-discharge voltage drop, fluid loss after case puncture, and energy density. The data are shown in Table 1.

[0099] Example 11

[0100] The specific preparation method is essentially the same as that of Example 2, except that the electrolyte is a gel electrolyte. A battery is formed by stacking the positive electrode sheet, separator, negative electrode sheet, and liquid electrolyte. Multiple charge and discharge cycles are performed, and the battery is tested for compression deformation under a force of 3000N, spontaneous discharge voltage drop, fluid loss after casing puncture, and energy density. The data are shown in Table 1.

[0101] Example 12

[0102] The specific preparation method is essentially the same as that in Example 2, differing in the composition of the binder and liquid absorbent in the polymer coating. A battery was constructed by stacking the positive electrode sheet, separator, negative electrode sheet, and gel electrolyte. Multiple charge and discharge cycles were performed, and the battery was tested for extrusion deformation under a force of 3000 N, spontaneous discharge voltage drop, fluid loss after casing puncture, and energy density. The data are shown in Table 1.

[0103] Comparative Example 1

[0104] Separately, the negative and positive electrodes were prepared, using graphite as the active material for the negative electrode and LiNi8Co1Mn1O4 as the active material for the positive electrode. A separator was also prepared, made of polyethylene. A liquid electrolyte was used. The positive electrode, separator, negative electrode, and liquid electrolyte were stacked to form a battery. Multiple charge and discharge cycles were performed, and the battery was tested for compression deformation under a force of 3000N, self-discharge voltage drop, fluid loss after case puncture, and energy density. The data are shown in Table 1.

[0105] Comparative Example 2

[0106] Separate negative and positive electrode sheets were prepared, using graphite as the active material for the negative electrode and LiNi8Co1Mn1O4 as the active material for the positive electrode. A polymer coating with a thickness of 1μm was applied to both the positive and negative electrodes, consisting solely of a binder. A separator was prepared, made of polyethylene, and a liquid electrolyte was used as the electrolyte. The positive electrode, separator, negative electrode, and liquid electrolyte were stacked to form a battery. Multiple charge and discharge cycles were performed, and the battery was tested for compression deformation under a force of 3000N, self-discharge voltage drop, fluid loss after case puncture, and energy density. The data are shown in Table 1.

[0107] Comparative Example 3

[0108] Separate negative and positive electrodes were prepared, using graphite as the active material for the negative electrode and LiNi8Co1Mn1O4 as the active material for the positive electrode. A polymer coating with a thickness of 1 μm was applied to both the positive and negative electrodes, containing only a liquid absorbent. A separator was prepared, made of polyethylene, and a liquid electrolyte was used as the electrolyte. The positive electrode, separator, negative electrode, and liquid electrolyte were stacked to form a battery. Multiple charge and discharge cycles were performed, and the battery was tested for compression deformation under a force of 3000 N, self-discharge voltage drop, fluid loss after case puncture, and energy density. The data are shown in Table 1.

[0109] Table 1 Battery parameters of each embodiment and comparative example

[0110] Note: Deformation refers to the deformation under 3000N force; pressure drop refers to the self-discharge voltage drop; fluid loss refers to the fluid loss due to shell puncture.

[0111] As can be seen from the data in Table 1, Comparative Example 1 does not include a polymer coating on the positive electrode, negative electrode, or separator, and the electrolyte is a liquid electrolyte. Comparative Example 2 includes a coating formed from the binder PVDF-HFP on each of the positive and negative electrode sheets, and the electrolyte is a liquid electrolyte. Comparative Example 3 includes a coating formed from the liquid absorbent polycarbonate diol on each of the positive and negative electrode sheets, and the electrolyte is a liquid electrolyte. The batteries of Examples 1-12, in which a polymer coating is provided on the positive electrode, negative electrode, or separator, and the polymer coating includes a binder and a liquid absorbent, show improvements and reductions in the post-cycle extrusion deformation under a force of 3000 N, the self-discharge voltage drop, and the liquid loss after casing puncture compared to Comparative Examples 1, 2, and 3. The batteries of Examples 1-5 include polymer coatings on both the positive and negative electrode sheets, with the coating thickness gradually increasing. In comparison, within a certain coating thickness range, the extrusion deformation under a force of 3000N after the cycle, the self-discharge voltage drop, and the amount of liquid lost after the shell is punctured are all improved, and the values ​​are all reduced; however, if the coating thickness is too large, it will affect the dynamics and energy density of the battery. Therefore, if the coating is too thick, it will have a bad effect. As shown in Example 5, the thickness of the polymer coating is 20μm. Compared with Comparative Example 1, Comparative Example 2, and Comparative Example 3, the extrusion deformation under a force of 3000N after the cycle, the self-discharge voltage drop, and the amount of liquid lost after the shell is punctured are all improved, and the values ​​are all reduced. However, compared with Example 4, the extrusion deformation under a force of 3000N after the cycle, the self-discharge voltage drop, and the amount of liquid lost after the shell is punctured have no obvious improvement effect. Therefore, the thickness of the polymer coating should be reasonably set. In the batteries of Examples 2, 6-9, polymer coatings were applied to the positive and negative electrodes, and the weight ratio of binder to liquid absorbent was gradually increased. In comparison, increasing the binder ratio improved the post-cycle extrusion deformation under a force of 3000 N and the self-discharge voltage drop; however, the amount of liquid lost after shell puncture increased as the amount of liquid absorbent decreased. In Example 10, a polymer coating was applied to the separator. The post-cycle extrusion deformation under a force of 3000 N, the self-discharge voltage drop, and the amount of liquid lost after shell puncture also improved, with the values ​​decreasing. In Example 11, polymer coatings were applied to the positive and negative electrodes, and the electrolyte was a gel electrolyte. The post-cycle extrusion deformation under a force of 3000 N, the self-discharge voltage drop, and the amount of liquid lost after shell puncture also improved, with the values ​​decreasing. This indicates that applying a strengthening layer to the electrode sheets or separator, i.e., adding a polymer coating, or using a gel electrolyte mixed with a polymer coating, enhances liquid absorption and retention, and can improve the mechanical strength and safety of the battery.

[0112] The above is only an implementation method of the present application and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the description and drawings of this application, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A polymer coating, comprising a binder and a liquid absorbent, wherein the binder comprises at least one of polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, and polyacrylic acid polymer; and the liquid absorbent comprises at least one of polyacrylate electrolytes, polyether electrolytes, polycarbonate electrolytes, polycarboxylate electrolytes, silicon-based electrolytes, polythiol, maleic anhydride electrolytes, and polysulfate electrolytes.

2. The polymer coating according to claim 1, wherein The weight ratio of the binder to the liquid absorbing agent is 0.5:1-9:1, and can be optionally 1:1-4:

1.

3. The polymer coating according to claim 1 or 2, wherein: The polymer coating comprises a solvent, and the solvent comprises one or more of nitrogen methyl pyrrolidone, acetone, and water.

4. The polymer coating according to any one of claims 1 to 3, wherein: The total mass concentration of the binder and the liquid absorbing agent in the polymer coating is 3%-15%.

5. Application of a polymer coating in a battery, characterized in that: The polymer coating according to any one of claims 1 to 4 is used as a functional coating in a battery.

6. The use according to claim 5, wherein: The battery comprises an electrode sheet and a separator, and the polymer coating is used as a functional coating of the electrode sheet and / or the separator.

7. An electrode sheet, wherein: The electrode sheet comprises a current collector and a reinforcement layer disposed on the current collector, wherein the reinforcement layer comprises a polymer coating, and the polymer coating comprises the polymer coating according to any one of claims 1 to 4.

8. The electrode sheet according to claim 7, wherein: The thickness of the strengthening layer is 0.5 μm-15 μm, and can be optionally 1 μm-5 μm.

9. The electrode sheet according to claim 7 or 8, wherein: The electrode sheet further includes an active material layer, and the active material layer is located between the current collector and the reinforcement layer.

10. The electrode sheet according to claim 9, wherein: The electrode sheet comprises a positive electrode sheet, and the positive electrode sheet comprises a positive electrode active material, and the positive electrode active material comprises one or more of lithium transition metal oxides and modified compounds thereof, lithium-containing phosphates with an olivine structure and modified compounds thereof, and lithium-containing phosphates with a spinel structure and modified compounds thereof.

11. The electrode sheet according to claim 9, wherein: The electrode sheet comprises a negative electrode sheet, the negative electrode sheet comprises a negative electrode active material, the negative electrode active material layer comprises a silicon-based material, and the silicon-based material comprises one or more of elemental silicon, silicon-oxygen compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys.

12. A separation film, wherein: The isolation film comprises a base film and a reinforcement layer disposed on the base film, wherein the reinforcement layer comprises a polymer coating, and the polymer coating comprises the polymer coating according to any one of claims 1 to 4.

13. The isolation film according to claim 12, wherein: The thickness of the strengthening layer is 0.5 μm-15 μm, and can be optionally 1 μm-5 μm.

14. The isolation film according to claim 12, wherein: The isolation membrane is selected from one or more materials selected from polyethylene, polypropylene, non-woven fabric, and polyvinylidene fluoride.

15. A battery, wherein: It comprises the electrode sheet as described in any one of claims 7 to 11, or the isolation membrane as described in any one of claims 12 to 14.

16. The battery according to claim 15, wherein The battery comprises a positive electrode sheet, a separator and a negative electrode sheet which are stacked; a reinforcement layer is arranged on the side of the negative electrode sheet facing the separator.

17. The battery according to claim 15 or 16, wherein: The battery also includes an electrolyte, and the electrolyte includes a gel electrolyte.

18. The battery according to claim 17, wherein The electrolyte includes monomers and initiators. The monomers include one or more of methyl methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, n-butyl methacrylate, butyl acrylate, n-octyl methacrylate, n-octyl acrylate, vinyl acetate, vinylene carbonate, vinylethylene carbonate, triethylene glycol dimethacrylate, diethylene glycol dimethacrylate, ethylene glycol dimethacrylate, allyl methacrylate, divinylbenzene, polyvinyl alcohol, and styrene. The initiator includes one or more of persulfate, azo initiator, and organic peroxide initiator.

19. An electrical device, wherein: Comprising a battery as claimed in any one of claims 15 to 18.

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