Secondary battery and electric device

Abstract

The invention provides a secondary battery and an electric device. The secondary battery comprises a pole piece, the pole piece comprises a current collector and a film layer arranged on at least one side of the current collector, the current collector comprises a metal current collector base material and a bottom coating layer arranged on at least one side of the metal current collector base material, the bottom coating layer comprises an inorganic oxide, and the film layer comprises an aqueous binder.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a secondary battery and an electrical device. Background Art

[0002] As energy and environmental issues become increasingly prominent, the new energy industry has received increasing attention. Secondary batteries, due to their high energy density and excellent cycle performance, have been widely used in recent years in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, and other fields.

[0003] Electrode sheets are important components of secondary batteries. Improving the quality of electrode sheets and further improving the performance of secondary batteries is a technical problem that needs to be solved urgently in this field. Summary of the Invention

[0004] The present application has been made in view of the above-mentioned problems, and an object of the present application is to provide a secondary battery with improved performance.

[0005] A first aspect of the present application provides a secondary battery, comprising a pole piece, the pole piece comprising a current collector and a film layer arranged on at least one side of the current collector, the current collector comprising a current collector substrate and a primer layer arranged on at least one side of the current collector substrate, the primer layer comprising an inorganic oxide, and the film layer comprising an aqueous binder.

[0006] Inorganic oxides have a high density and better affinity with metal current collector substrates. Compared to active materials (such as soft or hard carbon) or conductive agents (such as conductive carbon) commonly used in film layers, they are less likely to shrink or displace under the surface tension of the slurry. They can effectively improve the coating quality of the basecoat layer and achieve successful coating of liquid slurries with a large surface energy difference with the current collector substrate on the surface of the current collector substrate. Aqueous slurries containing aqueous binders have high surface tension, and when coated on current collector substrates, they often suffer from large surface energy differences and poor coating quality. Including inorganic oxides in the basecoat layer can especially solve the problem of poor compatibility between aqueous slurries and current collector substrates, improving the coating quality of aqueous slurries on current collector substrates.

[0007] In any embodiment, the inorganic oxide includes one or more of aluminum oxide, boehmite, magnesium oxide, iron oxide, silicon oxide, and zirconium oxide.

[0008] In any embodiment, based on the total mass of the primer layer, the inorganic oxide accounts for 30% to 60% by mass.

[0009] The basecoat layer contains inorganic oxides within the above mass range, which can not only improve the coating quality of the electrode, but also improve the bonding strength of the electrode, reduce the elongation of the electrode during cold pressing, and effectively control the current collector resistance while taking into account the electrochemical performance of the battery.

[0010] In any embodiment, the volume distribution particle size Dv50 of the inorganic oxide is less than 2 um.

[0011] The inorganic oxide with a volume distribution particle size within the above range can be closely attached to the metal current collector substrate, thereby improving the molding quality of the base coating and the pole piece.

[0012] In any embodiment, the primer layer further includes a particulate binder, and the particulate binder includes one or more of styrene-butadiene rubber and acrylic rubber.

[0013] The particulate binder is water-and-oil amphiphilic and exhibits better water resistance than linear binders that have a strong affinity for water solvents, allowing the primer layer to remain stable during the coating process of the upper film layer containing the active substance, further enhancing the role of the primer layer in improving the coating quality.

[0014] In any embodiment, the particulate binder accounts for 10% to 40% by mass based on the total mass of the primer layer.

[0015] The basecoat layer contains a particulate binder within the above mass range, which can not only improve the coating quality of the electrode, but also improve the bonding strength of the electrode, and can also effectively control the collector resistance while taking into account the electrochemical performance of the battery.

[0016] In any embodiment, the base coating further comprises a dispersant comprising one or more polyacrylic acid polymers.

[0017] Polyacrylic acid polymers are linear polymers that can be fully dispersed in the solvent to achieve coating of inorganic oxides, reduce the agglomeration of inorganic oxides, effectively disperse the inorganic oxides, assist the inorganic oxides to fully exert their effectiveness, further improve the molding quality of the primer layer, improve the coating quality and bonding strength of the pole piece, and reduce the elongation of the pole piece during cold pressing.

[0018] In any embodiment, based on the total mass of the primer layer, the mass proportion of the dispersant is 1%-8%, optionally 1%-5%.

[0019] Dispersants with a mass content within this range can not only effectively improve the bonding strength between the membrane layer and the current collector, but also reduce the adverse effects of reduced water resistance of the primer layer caused by excessively high acrylic acid content, thereby comprehensively improving the molding quality of the pole piece.

[0020] In any embodiment, the primer layer further comprises one or more of a conductive agent, a thickener, and a wetting agent.

[0021] Conductive agents can minimize the negative impact of the basecoat on the current collector's conductivity while also maintaining optimal battery electrochemical performance. Thickeners improve the dispersion of the conductive agent while reducing the sedimentation of the conductive agent and inorganic oxides, thereby enhancing the stability of the basecoat slurry and expanding the process window. Wetting agents improve the wetting of the film slurry on the current collector containing the oil film, facilitating the coating of the basecoat slurry onto the metal current collector substrate.

[0022] In any embodiment, the conductive agent includes one or more of Super-P, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers; and / or the thickener includes one or more of sodium carboxymethyl cellulose, sodium alginate, xanthan gum, and carrageenan; and / or the wetting agent includes one or more of polyoxyethylene surfactants, polyether silicone surfactants, non-ionic fluorocarbon polymer surfactants, and acetylene surfactants.

[0023] In any embodiment, based on the total mass of the primer layer, the mass proportion of the conductive agent is 10%-40%; the mass proportion of the thickener is 0.5%-4%; and the mass proportion of the wetting agent is 0.2%-1%.

[0024] In any embodiment, the primer layer has a thickness of 0.5 μm to 3 μm.

[0025] A primer layer with a thickness within an appropriate range can balance the molding quality and electrochemical performance of the battery.

[0026] In any embodiment, the current collector substrate is a metal current collector substrate, and the metal current collector substrate is prepared by a calendering method.

[0027] The metal current collector substrate prepared by the calendering method is low-cost and can further reduce the overall cost of the battery. However, after calendering, an oil film inevitably remains on the surface of the metal current collector substrate. This application is particularly suitable for this type of metal current collector substrate, comprehensively reducing the cost of secondary batteries.

[0028] In any embodiment, the current collector substrate has a dyne value of 20-35 mN / cm.

[0029] Water has a dyne value greater than 70 mN / cm, and the dyne value difference between the aqueous slurry and the metal current collector substrate is significant, making it difficult to achieve uniform coating on the surface. The present embodiment can effectively improve the coating quality of the aqueous slurry on the metal current collector substrate, which is beneficial for broadening the range of current collector substrates available and further reducing battery costs.

[0030] In any embodiment, the current collector substrate includes a metal current collector substrate, and the metal current collector substrate includes at least one of copper foil, aluminum foil, stainless steel foil, titanium foil, and nickel foil.

[0031] In any embodiment, the membrane layer further includes a negative electrode active material, which includes one or more of hard carbon, soft carbon, graphite, and silicon; and / or the aqueous binder includes one or more of styrene-butadiene rubber (SBR) and acrylic rubber.

[0032] In any embodiment, the secondary battery includes one or more of a sodium secondary battery and a lithium secondary battery.

[0033] In any embodiment, the secondary battery includes a sodium ion battery, and the single cell of the sodium ion battery includes: a battery case, an opening is provided at the upper portion of the battery case; a top cover assembly, the top cover assembly is provided at the opening of the battery case, the top cover assembly is sealed and electrically connected to the battery case; and an electrode assembly, the electrode assembly is used for electrical connection, the electrode assembly is provided on the top cover assembly; wherein the top cover assembly includes a top cover plate, and the electrode assembly and the top cover plate are constructed as a single integral component made of metal aluminum or alloy aluminum.

[0034] This sodium-ion battery achieves an optimized design of the battery top cover assembly while maintaining battery performance. By integrating the electrode assembly into the top cover assembly, it is constructed as a single integral component made of metal aluminum or alloy aluminum, which can reduce the number of structural parts and further reduce manufacturing costs. At the same time, it can achieve a charged connection between the battery housing and the electrode assembly, reducing the possibility of corrosion of the battery housing.

[0035] A second aspect of the present application provides an electric device, comprising the secondary battery of any embodiment.

[0036] A third aspect of the present application provides a current collector, comprising a current collector substrate and a primer layer disposed on at least one side of the current collector substrate, wherein the primer layer comprises an inorganic oxide.

[0037] In any embodiment, the inorganic oxide includes one or more of aluminum oxide, boehmite, magnesium oxide, iron oxide, silicon oxide, and zirconium oxide.

[0038] In any embodiment, the primer layer further includes a particulate binder, and the particulate binder includes one or more of styrene-butadiene emulsion and acrylic emulsion.

[0039] In any embodiment, the base coating further comprises a dispersant comprising one or more polyacrylic acid polymers.

[0040] In any embodiment, the current collector substrate is a metal current collector substrate, and the dyne value of the metal current collector substrate is 20-35 mN / m.

[0041] In any embodiment, the current collector substrate is a metal current collector substrate, and the metal current collector substrate comprises aluminum foil. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 Schematic diagram of a secondary battery according to one embodiment of the present application.

[0043] Figure 2 yes Figure 1 FIG. 1 is an exploded view of a secondary battery according to an embodiment of the present application.

[0044] Figure 3 Schematic diagram of a battery module according to one embodiment of the present application.

[0045] Figure 4 Schematic diagram of a battery pack according to one embodiment of the present application.

[0046] Figure 5 yes Figure 4 An exploded view of a battery pack according to an embodiment of the present application is shown.

[0047] Figure 6 FIG. 1 is a schematic diagram of an electrical device using a secondary battery according to an embodiment of the present application as a power source.

[0048] Description of reference numerals:

[0049] 1 battery pack; 2 upper case; 3 lower case; 4 battery module; 5 secondary battery; 51 housing; 52 electrode assembly; 53 top cover assembly. DETAILED DESCRIPTION

[0050] Below, the embodiments of the secondary battery and electrical device of the present application are described in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structure are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0051] The "ranges" disclosed herein are defined in terms of lower and upper limits. A given range is defined by selecting a lower limit and an upper limit, and the selected lower and upper limits define the boundaries of the particular range. Ranges defined in this manner are generally inclusive and can be combined arbitrarily, meaning that any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if the minimum range values ​​listed are 1 and 2, and if the maximum range values ​​listed are 3, 4, and 5, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise specified, the numerical range "ab" is an abbreviation for any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed herein, and "0-5" is merely an abbreviation for these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0052] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0053] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0054] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0055] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0056] Unless otherwise specified, the term "or" is used in this application to be inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied if any of the following conditions are met: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0057] As the demand for battery cost reduction increases, the urgency of using low-cost current collector substrates continues to increase. However, low-cost current collector substrates often use low-cost production processes during the manufacturing process, such as the calendaring method. During the rolling process, a layer of oil film is coated on the surface of the current collector substrate to reduce surface damage to the substrate. However, the oil film on the surface of the current collector substrate is not easy to remove, so when the aqueous slurry is applied to the surface of the current collector substrate, it cannot fully infiltrate the surface of the current collector substrate, resulting in difficulty in coating the aqueous slurry on the surface of the current collector substrate. Taking sodium secondary batteries as an example, since sodium ions do not react with aluminum metal to alloy like lithium ions, there are more types of negative electrode current collector materials to choose from. For example: the negative electrode of a sodium ion battery can use low-cost foils such as aluminum foil to replace the copper foil that is widely used in the existing technology to achieve further cost reduction. As an example, if the aluminum foil is prepared by the calendaring method, a layer of oil film will remain on the surface of the aluminum foil, making it difficult to coat the negative electrode aqueous slurry on its surface and it cannot be used for the negative electrode sheet.

[0058] A first aspect of the present application provides a secondary battery, comprising a pole piece, the pole piece comprising a current collector and a film layer arranged on at least one side of the current collector, the current collector comprising a current collector substrate and a primer layer arranged on at least one side of the current collector substrate, the primer layer comprising an inorganic oxide, and the film layer comprising an aqueous binder.

[0059] Inorganic oxides are inorganic compounds composed of oxygen atoms and one or more metal or non-metal elements.

[0060] The inorganic oxides in the primer layer can be tested using any known testing method. For example, the decomposition products in the film layer can be analyzed for phase using Raman spectroscopy, X-ray diffractometer, transmission electron microscope, or other testing instruments; or analyzed for composition using energy dispersive spectroscopy.

[0061] A water-based binder refers to a binder that uses an aqueous medium as a dispersant. Therefore, a film layer including a water-based binder is often prepared using an aqueous slurry. Water-based binders are divided into linear binders and particulate binders based on the dispersed morphology of the binder in the solvent. Linear binders have a linear morphology in the solvent and can achieve polymer chain extension in the solvent, so they are coated on the active materials in the film layer. Examples include, but are not limited to, polyacrylic acid and polymethyl acrylate. Particulate binders refer to binders that have a dot-like morphology in the solvent, mostly latex particles. Examples include, but are not limited to, styrene-butadiene rubber and propylene rubber.

[0062] Inorganic oxides have a high density and better affinity with the current collector substrate. Compared with the active materials (such as soft carbon or hard carbon) or conductive agents (such as conductive carbon) commonly used in the film layer, they are not easy to shrink or displace under the surface tension of the slurry, which can effectively improve the coating quality of the base coating.

[0063] The surface tension of the aqueous slurry including the aqueous binder is large, and when it is coated on the current collector substrate, there are often problems such as large surface energy differences and poor coating quality. Including inorganic oxides in the primer layer can especially solve the problem of poor compatibility between the aqueous slurry and the current collector substrate, and improve the coating quality of the aqueous slurry on the current collector substrate. It can be understood that the pole piece here can be a positive pole piece or a negative pole piece, and the embodiments of the present application can achieve corresponding technical effects for different battery systems. As an example, for the positive pole piece using an aqueous film slurry, the current collector provided in the embodiments of the present application can also provide improved pole piece coating quality. It should be noted that the secondary battery here is not limited to sodium secondary batteries, but also includes lithium secondary batteries.

[0064] It is understood that the material of the current collector is not particularly limited, as long as it does not cause chemical changes in the secondary battery and is conductive. The current collector includes metal foil with a pure metal content of 95% or more, such as at least one of copper foil, aluminum foil, stainless steel foil, titanium foil, and nickel foil. It also includes alloy foil containing at least two main elements, such as copper, aluminum, nickel, titanium, and iron. It can also include copper, aluminum-cadmium alloy, iron, or stainless steel surface-treated with carbon, nickel, titanium, silver, copper, etc. In addition, fine concave and convex surfaces can be formed to enhance the bonding with the negative electrode active material. The current collector can be used in various forms, such as films, sheets, foils, meshes, porous bodies, foams, and non-woven fabrics.

[0065] In some embodiments, the inorganic oxide includes one or more of aluminum oxide, boehmite, magnesium oxide, iron oxide, silicon oxide, and zirconium oxide.

[0066] In some embodiments, the inorganic oxide includes one or more of alumina and boehmite.

[0067] The above two inorganic oxides have better adhesion on aluminum foil, which can further improve the molding quality and bonding strength of the electrode.

[0068] In some embodiments, the inorganic oxide accounts for 30% to 60% by weight based on the total weight of the undercoat layer.

[0069] In some embodiments, based on the total mass of the undercoat layer, the mass proportion of the inorganic oxide may be 30%, 35%, 40%, 45%, 50%, 55%, 60% or any range therebetween.

[0070] The basecoat layer contains inorganic oxides within the above mass range, which can not only improve the coating quality of the electrode, but also improve the bonding strength of the electrode, reduce the elongation of the electrode during cold pressing, and effectively control the current collector resistance while taking into account the electrochemical performance of the battery.

[0071] In some embodiments, the volume distribution particle size Dv50 of the inorganic oxide is less than 2 um.

[0072] The volume distribution particle size Dv50 refers to the particle size corresponding to when the cumulative volume distribution percentage reaches 50% from the small particle size side in the particle size volume distribution diagram.

[0073] The volume distribution particle size Dv50 can be measured by any method known in the art. As an example, it can be measured with reference to GB / T19077-2016 particle size distribution laser diffraction method using a Mastersizer 2000E laser particle size analyzer from Malvern Instruments Ltd., UK.

[0074] The inorganic oxide with a volume distribution particle size within the above range can be closely attached to the metal current collector substrate, thereby improving the molding quality of the base coating and the pole piece.

[0075] In some embodiments, the primer layer further includes a particulate binder, and the particulate binder includes one or more of styrene-butadiene rubber and acrylic rubber.

[0076] A particulate binder refers to a binder that presents a dot-like morphology in the base coat. This type of binder generally presents a granular distribution in the solvent, and is mostly latex particles.

[0077] Styrene butadiene rubber (SBR) is also known as polystyrene butadiene copolymer.

[0078] Acrylate rubber is an elastomer obtained by copolymerizing acrylates as the primary monomer. The primary monomers include methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate. In some embodiments, the acrylate rubber includes styrene acrylic rubber (SAR), also known as styrene acrylic copolymer.

[0079] The particulate binder is water-and-oil amphiphilic and exhibits better water resistance than linear binders that have a strong affinity for water solvents, allowing the primer layer to remain stable during the coating process of the upper film layer containing the active substance, further enhancing the role of the primer layer in improving the coating quality.

[0080] In some embodiments, the particulate binder comprises acrylic rubber.

[0081] Compared with other particulate binders, acrylic rubber has stronger adhesion to the metal current collector substrate, which can further improve the coating quality and bonding strength of the electrode.

[0082] In some embodiments, the particulate binder accounts for 10% to 40% by mass based on the total mass of the primer layer.

[0083] In some embodiments, the mass proportion of the particulate binder based on the total mass of the primer layer can be 10%, 15%, 20%, 25%, 30%, 35%, 40%, or any range therebetween.

[0084] The basecoat layer contains a particulate binder within the above mass range, which can not only improve the coating quality of the electrode, but also improve the bonding strength of the electrode, and can also effectively control the collector resistance while taking into account the electrochemical performance of the battery.

[0085] In some embodiments, the base coating further comprises a dispersant comprising one or more polyacrylic acid polymers.

[0086] Polyacrylic acid polymers refer to polymers obtained by polymerizing acrylic acid or acrylic acid derivatives as monomers or copolymerizing them with other unsaturated compounds. It is understood that polyacrylic acid polymers can include both homopolymers and copolymers.

[0087] In some embodiments, the polyacrylic polymer includes one or more of polyacrylic acid, polymethacrylic acid, polyacrylamide, poly(acrylic acid-acrylamide), poly(acrylic acid-acrylonitrile), and poly(acrylic acid-acrylonitrile-acrylamide).

[0088] Polyacrylic acid polymers are linear polymers that can be fully dispersed in the solvent to achieve coating of inorganic oxides, reduce the agglomeration of inorganic oxides, effectively disperse the inorganic oxides, assist the inorganic oxides to fully exert their effectiveness, further improve the molding quality of the primer layer, improve the coating quality and bonding strength of the pole piece, and reduce the elongation of the pole piece during cold pressing.

[0089] In some embodiments, based on the total mass of the primer layer, the mass proportion of the dispersant is 1%-8%.

[0090] In some embodiments, based on the total mass of the primer layer, the mass proportion of the dispersant can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8% or any range therebetween.

[0091] Dispersants with a mass content within this range can not only effectively improve the bonding strength between the membrane layer and the current collector, but also reduce the adverse effects of reduced water resistance of the primer layer caused by excessively high acrylic acid content, thereby comprehensively improving the molding quality of the pole piece.

[0092] In some embodiments, the base coating further comprises one or more of a thickener, a conductive agent, and a wetting agent.

[0093] In some embodiments, the conductive agent includes one or more of Super-P, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0094] The conductive agent can minimize the negative impact of the undercoat layer on the conductivity of the current collector while taking into account the electrochemical performance of the battery.

[0095] In some embodiments, the thickener includes one or more of sodium carboxymethyl cellulose, sodium alginate, xanthan gum, and carrageenan.

[0096] On the one hand, the thickener is beneficial to improving the dispersion of the conductive agent, and on the other hand, it can reduce the sedimentation of the conductive agent and inorganic oxides, which is beneficial to improving the stability of the base coating slurry and expanding the process window.

[0097] In some embodiments, the wetting agent includes one or more of polyoxyethylene surfactants, polyether silicone surfactants, nonionic fluorocarbon polymer surfactants, and acetylene surfactants.

[0098] The wetting agent is helpful to improve the wetting of the film layer slurry on the current collector containing the oil film, so as to facilitate the coating of the primer slurry on the metal current collector substrate.

[0099] In some embodiments, based on the total mass of the primer layer, the mass proportion of the conductive agent is 10%-40%; the mass proportion of the thickener is 0.5%-4%; and the mass proportion of the wetting agent is 0.2%-1%.

[0100] In some embodiments, based on the total mass of the primer layer, the mass proportion of the conductive agent may be 10%, 20%, 30%, 40% or any range therebetween.

[0101] In some embodiments, based on the total mass of the base coating, the mass proportion of the thickener can be selected to be 0.5%, 1%, 2%, 3%, 4% or any range therebetween.

[0102] In some embodiments, the mass proportion of the wetting agent may be 0.2%, 0.4%, 0.6%, 0.8%, 1% or any range therebetween.

[0103] In some embodiments, the primer layer has a thickness of 0.5 μm to 3 μm.

[0104] In some embodiments, the thickness of the primer layer may be 0.5 μm, 1 μm, 2 μm, 3 μm, or any range therebetween.

[0105] A primer layer with a thickness within an appropriate range can balance the molding quality and electrochemical performance of the battery.

[0106] In some embodiments, the primer layer can be prepared by the following method: mixing an inorganic oxide and a dispersant in an aqueous solvent, stirring evenly, adding a thickener, and then successively adding a conductive agent, a binder, and a wetting agent to form a primer slurry; coating the primer slurry on a metal current collector substrate, and after drying, cold pressing and other processes, a current collector containing the primer layer can be obtained.

[0107] In some embodiments, the film layer further includes a negative electrode active material, and the negative electrode active material includes one or more of hard carbon, soft carbon, graphite, and silicon.

[0108] In some embodiments, the aqueous binder includes one or more of styrene-butadiene rubber (SBR) and acrylic rubber.

[0109] The above-mentioned particulate binder is different from linear binders such as polyacrylic acid. It can effectively alleviate the gel phenomenon of the membrane slurry and improve the brittleness problem of the membrane layer. The improvement effect is particularly significant for the slurry of negative electrode active materials including hard carbon, soft carbon, graphite, etc.

[0110] In some embodiments, the current collector substrate is a metal current collector substrate, and the metal current collector substrate is prepared by a calendering method.

[0111] The metal current collector substrate prepared by the calendering method is low-cost and can further reduce the overall cost of the battery. However, after calendering, an oil film inevitably remains on the surface of the metal current collector substrate. This application is particularly suitable for this type of metal current collector substrate, comprehensively reducing the cost of secondary batteries.

[0112] In some embodiments, the current collector substrate has a dyne value of 20-35 mN / m.

[0113] In some embodiments, the dyne value of the current collector substrate may be 20 mN / m, 25 mN / m, 30 mN / m, 35 mN / m, or any range therebetween.

[0114] The dyne value, also known as the surface tension coefficient, primarily describes the magnitude of surface tension, or the force per unit length between adjacent portions of a liquid surface. The dyne value can be used to measure the wettability of a current collector substrate; higher dyne values ​​indicate better wettability. The dyne value can be determined by any known method in the art. For example, a dyne pen can be used to measure the surface of a current collector substrate.

[0115] The dyne value of water is greater than 70mN / m, and the dyne value difference between the aqueous slurry and the above-mentioned current collector substrate is large, making it difficult to achieve uniform coating on the surface. The embodiments of the present application can effectively improve the coating quality of the aqueous slurry on the above-mentioned current collector substrate, which is conducive to broadening the range of current collector substrates available and further reducing battery costs. In some embodiments, the current collector substrate includes a metal current collector substrate, and the metal current collector substrate includes at least one of copper foil, aluminum foil, stainless steel foil, titanium foil, and nickel foil.

[0116] In some embodiments, the metal current collector substrate comprises aluminum foil.

[0117] The aluminum foil will spontaneously generate an aluminum oxide film on its surface, so that the oxide of the primer layer in the embodiment of the present application has a higher affinity with it, which can further improve the coating quality and bonding strength of the electrode.

[0118] In some embodiments, the film layer may further include a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0119] In some embodiments, the film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0120] In some embodiments, the electrode can be prepared by the following method: the components for preparing the electrode, such as active materials, conductive agents, binders and any other components, are dispersed in a solvent (such as deionized water) to form a film slurry; the film slurry is coated on the current collector, and after drying, cold pressing and other processes, the electrode can be obtained.

[0121] In some embodiments, the secondary battery includes one or more of a sodium secondary battery and a lithium secondary battery.

[0122] In some embodiments, the secondary battery is a sodium ion battery, and the electrode is a negative electrode.

[0123] In some embodiments, the secondary battery is a negative electrode-free battery, which may be a sodium negative electrode-free battery or a lithium negative electrode-free battery.

[0124] A negative electrode-free secondary battery refers to a battery that does not actively set a negative electrode active material layer on the negative electrode side during the battery manufacturing process. For example, a metal or carbonaceous active material layer is not set at the negative electrode through coating or deposition to form a negative electrode active material layer during the battery manufacturing process. During the first charge, the active ions on the anode side obtain electrons and are deposited on the surface of the current collector in the form of metal to form a metal phase. During discharge, the metal can be converted into active ions and return to the positive electrode, realizing cyclic charge and discharge. Therefore, a negative electrode-free secondary battery is also a metal battery. Compared with other secondary batteries, a negative electrode-free secondary battery can achieve higher energy density because there is no pre-set negative electrode active material layer.

[0125] Although it is not necessary to set a metal or carbonaceous active material layer by coating or deposition and other processes to form a negative electrode active material layer in a negative electrode-free secondary battery, a primer layer comprising a conductive material is often provided in a negative electrode-free secondary battery to induce deposition. Due to the large difference in surface tension, the coating of the aqueous primer layer of a negative electrode-free secondary battery on a current collector substrate with a low dyne value also has the problem of being difficult to form. The primer layer provided in the embodiment of the present application is also applicable to negative electrode-free secondary batteries, which improves the coating quality, and the inorganic oxide can further play a role in inducing metal deposition, which is conducive to further improving the uniformity of metal deposition.

[0126] In some embodiments, the secondary battery includes a sodium ion battery, and a single cell of the sodium ion battery includes: a battery case having an opening provided at an upper portion thereof; a top cover assembly disposed at the opening of the battery case, the top cover assembly being sealed and electrically connected to the battery case; and an electrode assembly, the electrode assembly being used for electrical connection and disposed on the top cover assembly; wherein the top cover assembly includes a top cover plate, and the electrode assembly and the top cover plate are constructed as a single integral component made of metal aluminum or alloy aluminum.

[0127] This sodium-ion battery achieves an optimized design of the battery top cover assembly while maintaining battery performance. By integrating the electrode assembly into the top cover assembly, it is constructed as a single integral component made of metal aluminum or alloy aluminum, which can reduce the number of structural parts and further reduce manufacturing costs. At the same time, it can achieve a charged connection between the battery housing and the electrode assembly, reducing the possibility of corrosion of the battery housing.

[0128] In some embodiments, the secondary battery further includes a positive electrode plate, the positive electrode plate includes a positive electrode collector and a positive electrode active material layer formed on at least a portion of the surface of the positive electrode collector, the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material may include at least one of a layered transition metal oxide, a polyanionic compound, and a Prussian blue compound.

[0129] The transition metal in the layered transition metal oxide can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. Optionally, the layered transition metal oxide is, for example, NaxMO2, wherein M is one or more of Ti, V, Mn, Co, Ni, Fe, Cr, and Cu, and 0<x≤1.

[0130] Polyanionic compounds can be metal ions, transition metal ions and tetrahedral (YO4) n- A class of compounds with anionic units. The metal ion can be selected from sodium ion, lithium ion, potassium ion, and zinc ion; the transition metal can be selected from at least one of Mg, Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Cr, Nb, Mo, In, Ge, Ga, Sn, Hf, Ta, W, and Pb; Y can be selected from at least one of P, S, and Si; n represents (YO4) n- valence.

[0131] As an optional embodiment of the present application, the chemical formula of the polyanionic compound can be Na x-a A a V y-b M b (PO4) 2-2c (DO4)2 c F z-d Q d, where element A represents an alkali metal element that dopes and replaces Na element, element M represents a metal element that replaces V element, element D represents a doping element that replaces P element, and element Q represents a doping element that replaces F element. The element D includes at least one of Si and S, and the element Q includes at least one of Cl and O; 3.5 ≤ x ≤ 4.5, 0 ≤ a ≤ 0.15x, 0.8 ≤ y ≤ 1.1, 0 ≤ b ≤ 0.3y, 0 ≤ c ≤ 0.15, 0.8 ≤ z ≤ 1.1, 0 ≤ d ≤ 0.2z. Optionally, the element A includes at least one of K and Li; the element M includes at least one of Fe, Cr, Al, Sc, Ga, In, Ti, Zr, Mn, Zn, Ni, Cu, and Co.

[0132] As an optional implementation manner of the present application, the general chemical formula of the polyanionic compound can be Na x R y (PO4)2P2O7, where x = 3.5 - 4.5, y = 2.75 - 3.25, and R includes at least one of Mg, Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Cr, Nb, Mo, In, Ga, Sn, Hf, Ta, W, and Pb.

[0133] As an optional implementation manner of the present application, the general chemical formula of the polyanionic compound can be Na 4+x R 3-y P 4- m O 15 / C; where 0 < x < 0.5, 0 < y ≤ 0.5, 0 < m ≤ 0.2, and R includes at least one of Mg, Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Cr, Nb, Mo, In, Ga, Sn, Hf, Ta, W, and Pb.

[0134] As an optional implementation manner of the present application, the general chemical formula of the polyanionic compound can be Na m Fe x (PO4) y P2O7 / C; where 3.6 ≤ m ≤ 4.4, 2.8 ≤ x ≤ 3, 2 ≤ y ≤ 2.1. The Prussian blue compound can be a kind of compound with sodium ions, transition metal ions, and cyanide ions (CN-). The transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. The Prussian blue compound is, 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.

[0135] In some embodiments, the positive electrode active material layer may further include a conductive agent to improve the conductivity of the positive electrode. The conductive agent may be selected from one or more of Super P, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphite, graphene, and carbon nanofibers.

[0136] In some embodiments, the positive electrode active material layer may further include a binder to firmly bond the positive electrode active material and the optional conductive agent to the positive electrode current collector. The binder may be at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyacrylic acid (PAA), polyvinyl alcohol (PVA), ethylene-vinyl acetate copolymer (EVA), styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), sodium alginate (SA), polymethacrylic acid (PMA), and carboxymethyl chitosan (CMCS).

[0137] In some embodiments, the positive electrode current collector may be a conductive carbon sheet, metal foil, carbon-coated metal foil, porous metal plate, or a composite current collector. The conductive carbon material of the conductive carbon sheet may be selected from one or more of Super P, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphite, graphene, and carbon nanofibers. The metal material of the metal foil, carbon-coated metal foil, and porous metal plate may each be independently selected from at least one of copper, aluminum, nickel, and stainless steel. The composite current collector may be a composite current collector formed by combining a metal foil with a polymer base film.

[0138] In some embodiments, the positive electrode sheet can be prepared by the following method: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0139] [Electrolytes]

[0140] The electrolyte conducts ions between the positive and negative electrodes. This application does not specify the type of electrolyte, and the electrolyte can be selected based on the needs. For example, the electrolyte can be liquid, gel, or solid.

[0141] In some embodiments, the electrolyte is an electrolyte solution comprising an electrolyte salt and a solvent.

[0142] In some embodiments, the electrolyte salt may be selected from at least one of sodium hexafluorophosphate, sodium bis(fluorosulfonyl)imide, sodium bis(trifluoromethanesulfonyl)imide, sodium trifluoromethanesulfonate, sodium tetrafluoroborate, sodium difluorophosphate, sodium perchlorate, and sodium chloride.

[0143] In some embodiments, the electrolyte contains an ester solvent, and the ester solvent contains at least one selected from ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, propylene carbonate, methyl acetate, ethyl propionate, and fluoroethylene carbonate.

[0144] In some embodiments, the electrolyte contains an ether solvent, and the ether solvent includes one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether and crown ether, and optionally includes one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether and tetraethylene glycol dimethyl ether.

[0145] In some embodiments, the electrolyte may further include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, and additives that improve battery high or low temperature performance.

[0146] In some embodiments, the secondary battery further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical and mechanical stability can be selected.

[0147] In some embodiments, 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, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0148] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be formed into an electrode assembly through a winding process or a lamination process.

[0149] In some embodiments, the secondary battery may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte.

[0150] In some embodiments, the outer packaging of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. Alternatively, the outer packaging of the secondary battery can be a soft shell, such as a pouch-type soft shell. The soft shell can be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0151] The present application has no particular restrictions on the shape of the secondary battery, which can be cylindrical, square or any other shape. For example, Figure 1 The secondary battery 5 is a square structure as an example.

[0152] In some embodiments, reference Figure 2 , the outer packaging may include a shell 51 and a cover plate 53. The shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can form an electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.

[0153] In some embodiments, secondary batteries can be assembled into a battery module. The number of secondary batteries contained in the battery module can be one or more. The specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0154] Figure 3 4 is an example of a battery module. Figure 3 In the battery module 4, the plurality of secondary batteries 5 may be arranged in sequence along the length of the battery module 4. Of course, they may also be arranged in any other manner. The plurality of secondary batteries 5 may further be fixed by fasteners.

[0155] Optionally, the battery module 4 may further include a housing having a receiving space, and the plurality of secondary batteries 5 are received in the receiving space.

[0156] In some embodiments, the battery modules described above may also be assembled into a battery pack. The battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art based on the application and capacity of the battery pack.

[0157] Figure 4 and Figure 5 The battery pack 1 is used as an example. Figure 4 and Figure 5 The battery pack 1 may include a battery box and multiple battery modules 4 disposed in the battery box. The battery box includes an upper box body 2 and a lower box body 3. The upper box body 2 can cover the lower box body 3 and form an enclosed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner in the battery box.

[0158] In addition, the present application also provides an electric device, which includes at least one of the secondary battery, battery module, or battery pack provided in the present application. The secondary battery, battery module, or battery pack can be used as a power source for the electric device, and can also be used as an energy storage unit for the electric device. The electric device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but is not limited thereto.

[0159] As the electrical device, a secondary battery, a battery module or a battery pack can be selected according to its usage requirements.

[0160] Figure 6 This is an example of an electric device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the secondary battery, a battery pack or battery module can be used.

[0161] Another example device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is generally required to be lightweight and thin, and may use a secondary battery as a power source.

[0162] Furthermore, the present application also provides a current collector, which includes a metal current collector substrate and a primer layer disposed on at least one side of the metal current collector substrate, wherein the primer layer includes an inorganic oxide.

[0163] It is understood that the current collector includes the current collector characteristics of the secondary battery in any embodiment.

[0164] Example

[0165] Below, the embodiment of the present application is described. The embodiment described below is exemplary and is only used to explain the present application, and is not to be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0166] Example 1

[0167] 1) Preparation of current collector

[0168] Preparation of primer slurry: Take 40 parts of aluminum oxide and 5 parts of polyacrylic acid, mix them in an aqueous solution, stir evenly, and then add 2 parts of thickener CMC-Na to form a uniform and stable aluminum oxide dispersion; after adding 29.7 parts of Super-P and stirring and dispersing evenly, add 28 parts of point adhesive styrene-butadiene emulsion and disperse for 30 minutes, and finally add 0.3 parts of wetting agent polyoxyethylene ether and disperse for 30 minutes to form a primer slurry with a solid content of 18%.

[0169] Coating of primer slurry: The primer slurry was evenly coated on the aluminum metal current collector substrate and dried to obtain the primer layer. The coating mass was 140 mg / 1540.25 mm 2 The dyne value of the aluminum metal current collector substrate is 20-35mN / m.

[0170] 2) Preparation of negative electrode sheet

[0171] The negative electrode active material hard carbon, conductive carbon black, aqueous binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC-Na) are fully stirred in a deionized water solvent system in a mass ratio of 96:2:1:1, and mixed evenly to obtain a negative electrode slurry; the negative electrode slurry is evenly coated on the negative electrode collector prepared in the previous step, and then dried, cold pressed, and cut to obtain a negative electrode sheet.

[0172] The preparation methods of Examples 2-8 are basically the same as those of Example 1, except that the specific components of the primer layer are adjusted, as shown in Table 1. In Example 4, the conductive agent is carbon nanotubes.

[0173] Comparative Example 1

[0174] The negative electrode active material hard carbon, conductive carbon black, binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC-Na) are fully stirred in a deionized water solvent system in a mass ratio of 96:2:1:1, and after mixing evenly, a negative electrode slurry is obtained; the negative electrode slurry is evenly coated on the surface of aluminum foil, and then dried, cold pressed, and cut to obtain a negative electrode sheet.

[0175] The preparation method of Comparative Example 2 is basically the same as that of Example 1, except that the specific components of the primer layer are adjusted, as shown in Table 1.

[0176] Table 1

[0177]

[0178] 2. Battery performance test

[0179] 1. Water resistance test of negative electrode current collector

[0180] The negative electrode current collector coated with the primer layer prepared above was punched using a punching machine to obtain a negative electrode current collector with an area of ​​about 2 mm2 For a sample, evenly apply 0.2g of water to one side of the primer layer and bake at 120°C for 5 minutes. Observe the sample using a CCD microscope. If the current collector substrate is exposed, the sample is considered unqualified. If the film layer tears or the primer layer migrates outward but the substrate is not exposed, the sample is considered qualified. If the film layer does not change significantly, the sample is considered good.

[0181] 2. Negative electrode coating quality test

[0182] Observe the coating quality of the prepared negative electrode sheet; if there is severe edge shrinkage and large-area coating omission, it is judged as unqualified; if there is a small amount of jagged edge shrinkage and a small amount of dot-shaped coating omission, it is judged as qualified; if there is no edge shrinkage and coating omission, and the film surface is flat and uniform, it is judged as good.

[0183] 3. Bond strength test

[0184] According to the test method in the national standard GB T 2791-1995, the peel strength between the negative electrode film layer and the current collector provided with the primer layer was tested.

[0185] 4. Pole elongation test

[0186] Take the negative electrode, remove the tab area, and mark three points horizontally at intervals of three meters along the direction of the electrode. The length of the two marking points is accurate to 0.1mm, and the length of the distance between two adjacent points is recorded as a. Adjust the left and right gaps and the tonnage of the cold press between 20 tons and 79 tons, and adjust the thickness of the cold press to achieve the ideal compaction density of the electrode. The compaction density of the electrode is measured to be 0.95g / cm 3 The length b of the electrode mark after cold pressing is η = (b / a-1) * 100%. Take two sections of each sample, and take three samples. The average of the six data points obtained from the test is used as the electrode elongation.

[0187] 5. Current collector resistance test

[0188] Use a sheet resistance meter (Yuanneng Technology) to test the current collector with primer. Take 5 samples for parallel testing. The average value is the sheet resistance of the current collector.

[0189] 3. Analysis of test results of various embodiments and comparative examples

[0190] Batteries of various examples and comparative examples were prepared according to the above methods, and various performance parameters were measured. The results are shown in Table 2 below.

[0191] Table 2

[0192]

[0193] As can be seen from the comparison of the embodiment and the comparative example, the secondary battery provided by the embodiment of the present application includes an inorganic oxide in the base coating, which can realize the coating of the aqueous film slurry on the surface of the aluminum foil, which is conducive to further reducing the cost of the sodium secondary battery. As can be seen from the comparison between Examples 1, 3, and 4, when the mass proportion of the inorganic oxide in the base coating is 30%-60%, the base coating can not only improve the coating quality of the aqueous slurry on the current collector substrate, but also can improve the mechanical bite force with the film layer by means of the rivet effect between the inorganic oxide and the negative electrode active material, thereby increasing the bonding strength between the film layer and the current collector; it can reduce the driving effect of the film layer extension on the current collector during the cold pressing process, and reduce the elongation rate of the current collector during the cold pressing process.

[0194] Table 3

[0195] Serial number Current collector sheet resistance (mΩ) Example 1 20 Example 2 18 Example 3 12 Example 4 15 Example 5 19 Example 6 24 Example 7 10 Example 8 40

[0196] As can be seen from Table 3, the mass proportion of inorganic oxide is 30%-60%, and the mass proportion of particulate binder is 10%-30%. It can improve the coating quality, bonding strength, and elongation of the electrode while taking into account the resistance, and can also take into account the electrochemical performance of the secondary battery while reducing costs.

[0197] Although the electrode coating quality was improved and qualified in Examples 6 and 7, a small amount of jagged edge shrinkage and a small amount of spot coating omissions appeared in the coating, making it impossible to accurately measure the electrode bonding strength and elongation. Therefore, their performance was not tested.

[0198] From the comparison between Examples 1, 2, and 5 and Example 6, it can be seen that when the mass proportion of the dispersant is 1%-5% based on the total mass of the primer layer, the interaction force between the water molecules in the aqueous negative electrode membrane slurry and the dispersant polyacrylic acid in the primer layer is maintained at an appropriate level, making it difficult for water molecules to insert between the molecules of the primer layer, the primer layer has good water resistance, and the coating appearance of the electrode is further improved.

[0199] From the comparison between Examples 1, 2, and 8 and Example 7, it can be seen that when the mass proportion of the particulate binder is greater than 10% based on the total mass of the primer layer, the particulate binder can provide sufficient bonding force in the primer layer, making it difficult for water molecules to insert between the molecules of the primer layer. The primer layer has good water resistance, and the coating appearance of the electrode is further improved.

[0200] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A secondary battery, characterized in that: The secondary battery includes a pole piece, which includes a current collector and a film layer arranged on at least one side of the current collector. The current collector includes a current collector substrate and a primer layer arranged on at least one side of the current collector substrate. The primer layer includes an inorganic oxide, and the film layer includes an aqueous binder.

2. The secondary battery according to claim 1, wherein The inorganic oxide includes one or more of aluminum oxide, boehmite, magnesium oxide, iron oxide, silicon oxide, and zirconium oxide.

3. The secondary battery according to claim 1 or 2, characterized in that Based on the total mass of the primer layer, the mass proportion of the inorganic oxide is 30%-60%.

4. The secondary battery according to any one of claims 1 to 3, characterized in that The volume distribution particle size Dv50 of the inorganic oxide is less than 2 μm.

5. The secondary battery according to any one of claims 1 to 4, characterized in that The primer layer further includes a particulate binder, and the particulate binder includes one or more of styrene-butadiene rubber and acrylic rubber.

6. The secondary battery according to claim 5, characterized in that The mass proportion of the particulate binder is 10% to 40% based on the total mass of the primer layer.

7. The secondary battery according to any one of claims 1 to 6, characterized in that The base coating layer further includes a dispersant comprising one or more polyacrylic acid polymers.

8. The secondary battery according to claim 7, wherein: Based on the total mass of the primer layer, the mass proportion of the dispersant is 1%-8%.

9. The secondary battery according to any one of claims 1 to 8, characterized in that Based on the total mass of the primer layer, the mass proportion of the dispersant is 1%-5%.

10. The secondary battery according to claim 8, wherein The primer layer further comprises one or more of a conductive agent, a thickener, and a wetting agent; the conductive agent comprises one or more of Super-P, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers; and / or The thickener includes one or more of sodium carboxymethyl cellulose, sodium alginate, xanthan gum, and carrageenan; and / or The wetting agent includes one or more of polyoxyethylene surfactants, polyether silicone surfactants, nonionic fluorocarbon polymer surfactants, and acetylene surfactants.

11. The secondary battery according to claim 10, wherein Based on the total mass of the primer layer, the mass proportion of the conductive agent is 10%-40%; the mass proportion of the thickener is 0.5%-4%; and the mass proportion of the wetting agent is 0.2%-1%.

12. The secondary battery according to any one of claims 1 to 11, characterized in that: The thickness of the primer layer is 0.5 μm-3 μm.

13. The secondary battery according to any one of claims 1 to 12, characterized in that: The current collector substrate is a metal current collector substrate, and the metal current collector substrate is prepared by a calendering method.

14. The secondary battery according to any one of claims 1 to 13, characterized in that The dyne value of the current collector substrate is 20-35 mN / m.

15. The secondary battery according to any one of claims 1 to 14, characterized in that The current collector substrate includes a metal current collector substrate, and the metal current collector substrate includes at least one of copper foil, aluminum foil, stainless steel foil, titanium foil, and nickel foil.

16. The secondary battery according to any one of claims 1 to 15, characterized in that The film layer further comprises a negative electrode active material, wherein the negative electrode active material comprises one or more of hard carbon, soft carbon, graphite, and silicon; and / or The aqueous binder includes one or more of styrene-butadiene rubber (SBR) and acrylic rubber.

17. The secondary battery according to any one of claims 1 to 16, characterized in that: The secondary battery includes one or more of a sodium secondary battery and a lithium secondary battery.

18. The secondary battery according to any one of claims 1 to 17, characterized in that The secondary battery includes a sodium ion battery, and the monomer of the sodium ion battery includes: A battery housing, wherein an opening is provided at an upper portion of the battery housing; a top cover assembly, the top cover assembly being disposed at the opening of the battery housing, the top cover assembly being sealed and electrically connected to the battery housing; as well as an electrode assembly, the electrode assembly being used for electrical connection and being disposed on the top cover assembly; The top cover assembly includes a top cover plate, and the electrode assembly and the top cover plate are constructed as a single integral component made of metal aluminum or alloy aluminum.

19. An electrical device, characterized in that: The electric device includes the secondary battery according to any one of claims 1 to 18.

20. A current collector, characterized in that: The current collector includes a current collector substrate and a primer layer disposed on at least one side of the current collector substrate, wherein the primer layer includes an inorganic oxide.

21. The current collector according to claim 20, characterized in that The inorganic oxide includes one or more of aluminum oxide, boehmite, magnesium oxide, iron oxide, silicon oxide, and zirconium oxide.

22. The current collector according to claim 20 or 21, characterized in that: The primer layer further includes a particulate binder, and the particulate binder includes one or more of styrene-butadiene emulsion and acrylic emulsion.

23. The current collector according to any one of claims 20 to 22, characterized in that The base coating layer further includes a dispersant comprising one or more polyacrylic acid polymers.

24. The current collector according to any one of claims 20 to 23, characterized in that The current collector substrate is a metal current collector substrate, and the dyne value of the metal current collector substrate is 20-35 mN / m.

25. The current collector according to any one of claims 20 to 24, characterized in that The current collector substrate is a metal current collector substrate, and the metal current collector substrate includes aluminum foil.

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