Alkali metal battery monomer, alkali metal battery and electric equipment

Abstract

The invention discloses an alkali metal battery monomer, an alkali metal battery and electric equipment. The alkali metal battery monomer comprises an electrode assembly and an adhesive tape, the adhesive tape partially covers the surface of the electrode assembly; the adhesive tape comprises an adhesive, and the adhesive comprises one or more of a rubber adhesive and a tert-butyl ester adhesive. The selected rubber adhesive is stable in performance and strong in alkali resistance, is relatively stable in an alkali metal battery system, and is not easy to hydrolyze; according to the selected tert-butyl ester adhesive, the steric hindrance of tert-butyl in the adhesive is relatively large, so that the tert-butyl ester adhesive is not easy to hydrolyze in an alkaline environment. By selecting a rubber adhesive and a tert-butyl ester adhesive as the adhesive of the adhesive layer, the stability of the adhesive tape in an alkali metal battery system can be improved.

Description

Technical Field

[0001] The present application relates to the field of new energy technology, and in particular to alkali metal battery cells, alkali metal batteries and electrical equipment. Background Art

[0002] With the continuous development of new energy technologies, power batteries are widely used in various consumer electronic products, electric vehicles, aerospace and other fields. The battery includes a battery cell, and the battery cell includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode plate, a negative electrode plate and a separator. In order to improve the stability of each component in the battery cell, tape is usually used to fix the components. However, when the tape is immersed in the electrolyte for a long time, the adhesive of the tape is easily destroyed by hydrolysis, which will not only reduce the adhesive fixation of the tape, resulting in reduced mechanical stability of the battery, but may also produce side reactions, affecting the battery's cycle and storage performance. The above statements are only used to provide background technical information related to this application and do not necessarily constitute prior art. Summary of the invention

[0003] The main technical problem solved by the present application is to provide an alkali metal battery cell, an alkali metal battery and an electrical device, which can improve the stability of the tape in the alkali metal system.

[0004] In order to solve the above technical problems, a technical solution adopted in the present application is: to provide an alkali metal battery cell, the alkali metal battery cell includes an electrode assembly and a tape; the tape partially covers the surface of the electrode assembly; the tape includes an adhesive, and the adhesive includes one or more of a rubber adhesive and a tert-butyl ester adhesive. In this embodiment, the selected rubber adhesive has stable performance, strong alkali resistance, is relatively stable in the alkali metal battery system, and is not easy to hydrolyze; the selected tert-butyl ester adhesive has a large steric hindrance of the tert-butyl group in the adhesive, so that the tert-butyl ester adhesive is not easy to hydrolyze in an alkaline environment. By selecting a rubber adhesive or a tert-butyl ester adhesive as the adhesive of the adhesive layer, the stability of the tape in the alkali metal battery system can be improved.

[0005] In one embodiment, the rubber adhesive includes EPDM rubber; the tert-butyl ester adhesive includes one or more of tert-butyl acrylate and tert-butyl methacrylate. In this embodiment, the selected EPDM rubber has stable performance, strong alkali resistance, is relatively stable in an alkaline electrolyte system, and is not easily hydrolyzed; the tert-butyl group in the selected tert-butyl acrylate and tert-butyl methacrylate has a large steric hindrance, making the tert-butyl ester adhesive not easily hydrolyzed in an alkaline environment. By selecting EPDM rubber, tert-butyl acrylate, and tert-butyl methacrylate as the adhesive of the adhesive layer, the stability of the tape in the electrolyte can be improved.

[0006] In one embodiment, the adhesive tape includes a base layer and an adhesive layer, the adhesive layer is located on one side of the base layer, and the adhesive layer includes 1%-15% adhesive, 1%-15% tackifying resin, 0.1%-10% green pigment, and 75%-95% polyethylene terephthalate by mass. Through this arrangement, the adhesive tape can have relatively strong adhesion, improve the stability of the fixed structure, and is not easy to hydrolyze in the electrolyte. For example, the content of the adhesive can be 1%, 3%, 5%, 7%, 9%, 10%, 13%, 15%, etc. A high content of adhesive can improve the adhesive strength, but too much adhesive will cause side reactions after being immersed in the electrolyte for a long time, affecting the circulation and storage performance of the battery.

[0007] In one embodiment, the thickness of the base layer is 2-12 μm; for example, it can be 2 μm, 4 μm, 6 μm, 8 μm, 10 μm, 12 μm, etc. The base layer can be a polyimide (PI) material. The base layer can provide support and adhesion for the adhesive, while protecting the adhesive and preventing the adhesive from direct contact with the electrolyte to a certain extent.

[0008] In one embodiment, the thickness of the adhesive layer is 2-8 μm. For example, it can be 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, etc. The thicker the adhesive layer, the better the bonding stability of the tape. However, it will increase the total amount of adhesive and cause side reactions after soaking in electrolyte, affecting the cycle and storage performance of the battery. If the adhesive layer is too thin, the bonding performance will decrease.

[0009] In one embodiment, when the alkali metal battery cell is charged and discharged at 25°C and the internal pressure of the battery cell reaches 0.35 MPa, the number of cycles of the battery cell is greater than 200. In this embodiment, by selecting a tape with more stable performance, the side reactions in the battery system are reduced, the amount of gas generated is reduced, and the battery charge and discharge cycle performance is improved.

[0010] In one embodiment, when the alkali metal battery cell is stored at 25°C and the internal pressure of the battery cell reaches 0.60 MPa, the storage days of the battery cell are greater than 360 days. In this embodiment, by selecting a tape with more stable performance, the side reactions in the battery system are reduced, the amount of gas generated is reduced, and the battery storage performance is improved.

[0011] In one embodiment, the gas generation of the alkali metal battery monomer is less than 0.06 ml / Ah / cycle during charge and discharge at 25° C. In this embodiment, by selecting a tape with more stable performance, the side reactions in the battery system are reduced, the amount of gas generated is reduced, and the safety and cycle life of the battery are improved.

[0012] In one embodiment, the gas generation of the alkali metal battery monomer is less than 0.04 ml / Ah / day when stored at 25° C. In this embodiment, by selecting a tape with more stable performance, the side reactions in the battery system are reduced, the amount of gas generated is reduced, and the safety and storage performance of the battery are improved.

[0013] In one embodiment, the electrolyte of the alkali metal battery monomer includes one or more solvents selected from chain ethers, ethylene glycol dimethyl ether and its derivatives, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, and cyclic ethers. By selecting these solvents as the electrolyte system solvent, side reactions in the electrolyte system can be reduced and battery gas generation can be reduced.

[0014] In one embodiment, the positive electrode material of the alkali metal battery monomer includes one or more of a polyanion positive electrode material, a phosphate positive electrode material, a sulfate positive electrode material, a silicate positive electrode material, and a borate positive electrode material. By selecting these types of electrode materials, the electrode material has good stability, less side reactions in the battery system, and reduced battery gas production.

[0015] In one embodiment, the negative electrode material of the alkali metal battery cell includes one or more of conductive carbon, graphite, hard carbon, and carbon nanotubes. These negative electrode materials are selected because they have good surface structure, stable chemical properties, and good electrical conductivity.

[0016] In one embodiment, the negative electrode active material of the alkali metal battery cell is sodium metal. In this embodiment, the battery is a sodium metal battery system, which has stable system performance and high battery capacity.

[0017] In one embodiment, the tape at least partially covers the electrode tab weld mark to protect the electrode tab weld mark.

[0018] To solve the above technical problems, another technical solution adopted by the present application is to provide an alkali metal battery, the alkali metal battery comprising any of the above alkali metal battery monomers. The obtained battery has strong mechanical stability and high cycle and storage performance.

[0019] In one embodiment, the adhesive tape is used to bond and fix adjacent alkali metal battery cells to improve the stability of the battery.

[0020] To solve the above technical problems, another technical solution adopted by the present application is to provide an electrical device, which includes the above alkali metal battery. The electrical device has at least the same advantages as the battery and can enhance the safety of the electrical device.

[0021] 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

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 is a schematic diagram of an exploded structure of a battery according to one or more embodiments;

[0024] Figure 2 is a schematic diagram of an exploded structure of a battery cell according to one or more embodiments;

[0025] Figure 3 is a schematic diagram of the structure of an adhesive tape according to one or more embodiments;

[0026] Figure 4 is a schematic diagram of the structure of an adhesive tape according to one or more embodiments;

[0027] Figure 5 is a schematic structural diagram of a vehicle according to one or more embodiments;

[0028] Figure 6 Schematic diagram of gas production data of Example 1 and Comparative Example 1.

[0029] 1000, vehicle; 300, motor; 200, controller; 100, battery; 10, housing; 11, first part; 12, second part; 20, battery cell; 21, end cover; 21a, electrode terminal; 22, housing; 23, electrode assembly.

[0030] 40. Adhesive tape; 41. Base layer; 43. Adhesive layer; 431. Middle area; 433. Edge area. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and effect of the present application clearer and more specific, the following will describe the embodiments of the technical solution of the present application 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 used as examples, and cannot be used to limit the scope of protection of the present application.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field 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" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0033] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, 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 groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces), unless otherwise clearly and specifically defined.

[0034] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0035] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0036] Amounts, ratios and other numerical values ​​are presented herein in a range format. It should be understood that such a range format is for convenience and brevity and should be flexibly interpreted to include not only the values ​​explicitly specified as range limits, but also all individual values ​​or sub-ranges encompassed within the range, as if each value and sub-range were explicitly specified.

[0037] If there is no special explanation, all steps of the present application can be performed sequentially, randomly, or in parallel, 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, or may be steps (a) and (b) performed simultaneously in parallel. For example, the method may also include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0038] With the development of new energy vehicles and large-scale energy storage, the demand for traditional lithium-ion batteries is increasing, but the reserves of lithium resources are limited and the price is gradually rising. Therefore, it is necessary to develop new energy storage devices with abundant resources and low prices. In order to obtain lithium-ion batteries with high capacity, metal materials such as silicon (4200mAh / g) and tin (990mAh / g) with high storage capacity characteristics by alloying reaction with lithium are used as negative electrode active materials. However, when metals such as silicon and tin are used as negative electrode active materials, their volume expands to about 4 times during the charging process of alloying with lithium, and shrinks again during the discharge process. Due to the large volume change of the electrode assembly repeatedly occurring during the charge / discharge process, the active material gradually micronizes and falls off the electrode, so the capacity decreases rapidly, making it difficult to ensure stability and reliability.

[0039] Compared with the above-mentioned negative electrode active materials, alkali metals such as lithium, sodium and potassium have higher specific capacity, especially metallic lithium, whose theoretical specific capacity is as high as 3860mAh / g and the electrode potential is as low as -3.04V (relative to H2 / H+). Therefore, the development of alkali metal batteries with metal as negative electrode has once again attracted the attention of scientific researchers.

[0040] The present application provides an electrochemical device, which includes any device that undergoes an electrochemical reaction. Specific examples thereof include alkali metal batteries, which may be sodium metal batteries, lithium metal batteries, potassium metal batteries, and the like.

[0041] Please refer to Figure 1 , Figure 11 is a schematic diagram of the exploded structure of a battery according to one or more embodiments. The battery 100 includes a box body 10 and a battery cell 20, and the battery cell 20 is accommodated in the box body 10. Among them, the box body 10 is used to provide a storage space for the battery cell 20, and the box body 10 can adopt a variety of structures. In some embodiments, the box body 10 may include a first part 11 and a second part 12, and the first part 11 and the second part 12 cover each other, and the first part 11 and the second part 12 jointly define a storage space for accommodating the battery cell 20. The second part 12 may be a hollow structure with one end open, and the first part 11 may be a plate-like structure, and the first part 11 covers the open side of the second part 12, so that the first part 11 and the second part 12 jointly define a storage space; the first part 11 and the second part 12 may also be hollow structures with one side open, and the open side of the first part 11 covers the open side of the second part 12. Of course, the box body 10 formed by the first part 11 and the second part 12 may be in a variety of shapes, such as a cylinder, a cuboid, etc.

[0042] 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 mixed connection. A mixed connection means that the multiple battery cells 20 are both connected in series and in parallel. The multiple battery cells 20 may be directly connected in series, in parallel, or in a mixed connection, and then the whole formed by the multiple battery cells 20 is accommodated in the box 10; of course, the battery 100 may also be a battery module formed by connecting multiple battery cells 20 in series, in parallel, or in a mixed connection, and then the multiple battery modules are connected in series, in parallel, or in a mixed connection to form a whole, and accommodated in the box 10. The battery 100 may also include other structures, for example, the battery 100 may also include a busbar component for realizing electrical connection between the multiple battery cells 20.

[0043] Each battery cell 20 may be a secondary battery or a primary battery. The battery cell 20 may be cylindrical, flat, rectangular or in other shapes.

[0044] Please refer to Figure 2 , Figure 2 2 is a schematic diagram of the exploded structure of a battery cell according to one or more embodiments. A battery cell 20 refers to the smallest unit that constitutes a battery. Figure 2 The battery cell 20 includes an end cover 21, a shell 22, an electrode assembly 23 and other functional components.

[0045] The end cap 21 refers to a component that covers the opening of the shell 22 to isolate the internal environment of the battery cell 20 from the external environment. Without limitation, the shape of the end cap 21 can be adapted to the shape of the shell 22 to match the shell 22. Optionally, the end cap 21 can be made of a material with a certain hardness and strength (such as aluminum alloy), so that the end cap 21 is not easily deformed when squeezed and collided, so that the battery cell 20 can have a higher structural strength and the safety performance can also be improved. Functional components such as electrode terminals 21a can be provided on the end cap 21. The electrode terminal 21a can be used to electrically connect to the electrode assembly 23 for outputting or inputting electrical energy of the battery cell 20. In some embodiments, the end cap 21 can also be provided with a pressure relief mechanism for releasing the internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold. The material of the end cap 21 can also be a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiments of the present application do not impose special restrictions on this. In some embodiments, an insulating member may be provided inside the end cap 21, and the insulating member may be used 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 plastic, rubber, or the like.

[0046] The shell 22 is a component used to cooperate with the end cap 21 to form the internal environment of the battery cell 20, wherein the formed internal environment can be used to accommodate the electrode assembly 23, the electrolyte and other components. The shell 22 and the end cap 21 can be independent components, and an opening can be set on the shell 22, and the internal environment of the battery cell 20 is formed by covering the opening with the end cap 21 at the opening. Without limitation, the end cap 21 and the shell 22 can also be integrated. Specifically, the end cap 21 and the shell 22 can form a common connection surface before other components are put into the shell, and when the interior of the shell 22 needs to be encapsulated, the end cap 21 covers the shell 22. The shell 22 can be of various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shape of the shell 22 can be determined according to the specific shape and size of the electrode assembly 23. The material of the shell 22 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiment of the present application does not impose any special restrictions on this.

[0047] The electrode assembly 23 is a component in the battery cell 20 where electrochemical reactions occur. One or more electrode assemblies 23 may be included 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 tab and the negative tab 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 tab 23a connects the electrode terminals to form a current loop.

[0048] In one embodiment, the positive electrode sheet includes a positive electrode current collector and a positive electrode active layer disposed on at least one side of the positive electrode current collector, and the positive electrode active layer includes a positive electrode active material.

[0049] As an example, the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer can be disposed on any one or both of the two opposite surfaces of the positive electrode current collector.

[0050] In one embodiment, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0051] Positive electrode active materials include one or more of polyanion positive electrode materials, phosphate positive electrode materials, sulfate positive electrode materials, silicate positive electrode materials, and borate positive electrode materials. For example, among the positive electrode active materials of sodium metal batteries, the polyanion compounds that are more studied are compounds based on phosphoric acid and fluorophosphate. Among the compounds based on phosphoric acid, Na x1 Fe y1 P m1 O n1It has received extensive attention due to its high capacity and voltage platform. For example, sodium iron phosphate with a high capacity can provide a higher energy density for sodium metal batteries; sodium iron pyrophosphate with a higher voltage platform can provide a higher rate performance for sodium metal batteries. Polyanionic compounds include one or more of sodium vanadium trifluorophosphate Na3V2(PO4)2F3, sodium vanadium fluorophosphate NaVPO4F, sodium vanadium phosphate Na3V2(PO4)3, Na4Fe3(PO4)2P2O7, NaFePO4, and Na3V2(PO4)3. Prussian blue compounds are NaxMM(CN)6, where M, M are one or more of Fe, Mn, Co, Ni, Cu, Zn, Cr, Ti, V, Zr, and Ce, and 0<x≤2. The positive electrode active material in the lithium metal battery may include at least one of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, or lithium manganese iron phosphate.

[0052] In one embodiment, the positive electrode film layer may further include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

[0053] In one embodiment, the positive electrode film layer includes a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0054] The negative electrode sheet generally includes a negative electrode current collector, or includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material.

[0055] As an example, the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer may be disposed on any one or both of the two opposite surfaces of the negative electrode current collector.

[0056] In one embodiment, the negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, a copper foil may be used. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be obtained by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0057] In a sodium metal battery, the negative electrode plate of the battery is the negative electrode current collector, that is, the negative electrode current collector directly serves as the negative electrode plate. This type of battery can also be called a "negative electrode-free battery". During the charging process, sodium ions released from the positive electrode active material are deposited on the negative electrode current collector to form sodium metal (that is, the negative electrode active material is sodium metal). In other embodiments, in order to ensure the normal use of the negative electrode plate or to facilitate the deposition of sodium metal on the negative electrode current collector, a conductive film layer can be deposited on the negative electrode current collector.

[0058] In one embodiment, the negative electrode active material may adopt the negative electrode active material for sodium batteries known in the art. As an example, the negative electrode active material may include at least one of the following materials: a carbon-based material, an alloy material, a titanium-based material, sodium metal, a carbon-based material deposited with sodium metal, a composite material containing sodium metal, an alloy material containing sodium metal, and the like. The above-mentioned carbon-based materials include but are not limited to graphite, soft carbon, hard carbon, carbon microspheres, carbon fibers, carbon nanotubes, and conductive carbon. The above-mentioned alloy materials include but are not limited to sodium-tin alloys, sodium-germanium alloys, and sodium-antimony alloys. The above-mentioned titanium-based materials include but are not limited to titanium dioxide, titanates, and titanium phosphates. The present application may also use other materials that can be used as negative electrode active materials for sodium batteries. These negative electrode active materials may be used alone or in combination of two or more materials. The negative electrode material may also be lithium metal, lithium alloy, potassium metal, or potassium alloy.

[0059] The electrolyte plays the role of conducting ions between the positive electrode and the negative electrode. The present application has no specific restrictions on the type of electrolyte, which can be selected according to needs. For example, the electrolyte can be liquid, gel or all-solid.

[0060] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.

[0061] In one embodiment, the electrolyte salt includes sodium hexafluorophosphate (NaPF6), sodium bis(fluorosulfonyl)imide (NaFSI), sodium trifluoromethanesulfonate, sodium sulfide (Na2S), etc. The lithium salt includes at least one of lithium perchlorate, lithium hexafluoroarsenate, lithium hexafluorophosphate, lithium bis(trifluoromethylsulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium difluorooxalatoborate, lithium tetrafluoroborate, and lithium trifluoromethanesulfonate.

[0062] In one embodiment, the solvent includes one or more solvents selected from chain ethers, ethylene glycol dimethyl ether and its derivatives, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, and cyclic ethers, including dimethyl ether (DME), diethylene glycol dimethyl ether, diethylene glycol diethyl ether, tetraethylene glycol dimethyl ether, 2,2,2,2-trifluoroethyl ether, ethylene glycol diethyl ether, triethylene glycol dimethyl ether, methyl trifluoroethyl carbonate (FEMC), dioxolane (DOL), acetonitrile (AN), fluorobenzene, triethyl phosphate (TEP), sulfolane, 2-methyltetrahydrofuran, tetrahydrofuran, dimethyl sulfoxide, N,N-dimethylacetamide, etc.

[0063] In one embodiment, the electrolyte may further include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.

[0064] In one embodiment, the isolation membrane can be any known porous structure isolation membrane with good chemical stability and mechanical stability.

[0065] In one embodiment, the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The isolation membrane can be a single-layer film or a multi-layer composite film, without particular limitation. When the isolation membrane is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0066] In one embodiment, a large-area tape is often used in an alkali metal battery cell to bond and fix the electrode plates, tabs, etc. That is, the alkali metal battery cell also includes a tape, and the tape partially covers the surface of the electrode assembly and is used to fix the electrode assembly. For example, it is used as a termination tape to fix the end of the electrode plate in a wound battery; it can also be used as a protective tape to cover the tab weld mark and protect the tab weld mark. Furthermore, it can also be used to fix and connect two adjacent battery cells.

[0067] At present, the adhesives commonly used in adhesive tapes include polymethyl acrylate, polyethyl acrylate, polypropyl acrylate, polybutyl acrylate, polypentyl acrylate, polyoctyl acrylate, etc. However, the electrolyte system of alkali metal batteries is alkaline. When the adhesive tape is immersed in the electrolyte for a long time, these ester substances are prone to saponification reaction under strong alkaline conditions and then hydrolyze, as follows:

[0068]

[0069] After hydrolysis, not only will the tape turn black, but it will also produce a large amount of gas, which will affect the cycle and storage performance of the battery cells. Blue glue will produce bubbles and turn black easily after being used for a long time.

[0070] See also Figure 3 , Figure 3 Schematic diagram of the structure of an adhesive tape according to one or more embodiments. The present application provides an adhesive tape 40 for an alkali metal battery, the adhesive tape 40 comprises a base layer 41 and an adhesive layer 43, the adhesive layer 43 is located on one side of the base layer 41, and the adhesive layer 43 comprises an adhesive, and the adhesive comprises one or more of a rubber adhesive and a tert-butyl ester adhesive.

[0071] In this embodiment, the selected rubber adhesive has stable performance, strong alkali resistance, is relatively stable in the alkali metal battery system, and is not easy to hydrolyze; the selected tert-butyl ester adhesive has a large steric hindrance of the tert-butyl group in the adhesive, which makes the tert-butyl ester adhesive not easy to hydrolyze in an alkaline environment. By selecting rubber adhesives and tert-butyl ester adhesives as adhesives for the adhesive layer, the stability of the adhesive layer in the alkali metal battery system can be improved. The tape provided in this application has no obvious changes on the surface after long-term use and has stable performance.

[0072] In one embodiment, the rubber adhesive includes EPDM rubber; the tert-butyl ester adhesive includes one or more of tert-butyl acrylate and tert-butyl methacrylate.

[0073] In this embodiment, the selected EPDM rubber has stable performance and strong alkali resistance, is relatively stable in the alkaline electrolyte system of the alkali metal battery, and is not easy to hydrolyze; the tert-butyl group in the selected tert-butyl acrylate and tert-butyl methacrylate has a large steric hindrance, so that the tert-butyl ester adhesive is not easy to hydrolyze in an alkaline environment. By selecting EPDM rubber, tert-butyl acrylate, and tert-butyl methacrylate as the adhesive of the adhesive layer, the stability of the adhesive layer in the electrolyte can be improved.

[0074] In one embodiment, the adhesive layer includes 1%-15% adhesive, 1%-15% tackifying resin, 0.1%-10% green pigment, and 75%-95% polyethylene terephthalate by weight. This configuration can make the adhesive tape have a relatively strong adhesiveness, improve the stability of the fixed structure, and not easily hydrolyze in the electrolyte.

[0075] The base material includes polyethylene (PE) and polyimide (PI). The tackifying resin includes rosin, terpene resin, C5 or C9 petroleum resin, hydrogenated / modified resin, such as at least one of hydrogenated petroleum resin, hydrogenated rosin resin, and hydrogenated terpene resin.

[0076] In one embodiment, the content of the adhesive may be 1%, 3%, 5%, 7%, 9%, 11%, 13%, 15%, etc. or a range consisting of any two of the above values, for example, 1%-3%, 3%-5%, 5%-7%, 7%-11%, 11%-15%, etc. By controlling the content of the adhesive, the adhesiveness of the tape can be regulated. On the basis of maintaining the adhesiveness, the use of the adhesive can be minimized to reduce the interaction with the electrolyte and the generation of gas, etc.

[0077] The content of the tackifying resin can be 1%, 3%, 5%, 7%, 9%, 11%, 13%, 15%, etc. or a range consisting of any two of the above values, for example, 1%-3%, 3%-5%, 5%-7%, 7%-11%, 11%-15%, etc. The tackifying resin includes a room temperature solid tackifying resin and a room temperature liquid tackifying resin, wherein the room temperature solid tackifying resin is rosin, terpene resin, C5 or C9 petroleum resin, hydrogenated / modified resin.

[0078] The content of green pigment can be 0.1%, 0.5%, 1%, 3%, 5%, 7%, 9%, 10%, etc. Or it can be a range consisting of any two of the above values, for example, 0.1%-0.5%, 0.5%-1%, 1%-3%, 3%-5%, 5%-7%, 7%-10%, etc. The green pigment can be cobalt green, zinc flower, zirconium oxide, etc.

[0079] The polyethylene terephthalate content may be 75%, 80%, 85%, 90%, 95%, etc., or a range consisting of any two of the above values, for example, 75%-80%, 80%-85%, 85%-90%, 90%-95%, etc.

[0080] In one embodiment, the adhesive layer further includes 1%-10% of an acidic material. The amount of the acidic material added may be 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, etc. Or it may be a range consisting of any two of the above values, for example, 1%-3%, 3%-5.5%, 5.5%-7%, 7%-10%, etc. By adding an acidic material, when the electrolyte erodes the adhesive layer, the alkali in the electrolyte can be neutralized, thereby reducing the risk of the adhesive being hydrolyzed when encountering alkali.

[0081] In one embodiment, the acidic material includes one or more of ammonium polyphosphate, antimony chloride, antimony fluoride, zinc chloride, tin chloride, chromium chloride, and aluminum chloride. The selected acidic material ammonium polyphosphate can also have a flame retardant effect, reducing the risk of fire in the battery cell. The selected acidic materials antimony chloride, antimony fluoride, zinc chloride, tin chloride, chromium chloride, and aluminum chloride are metal salts with Lewis acidity, which can not only neutralize the alkali in the electrolyte, but also combine with the water generated in the electrolyte to form a stable compound, play a "water removal" role, and reduce the risk of water corrosion on the electrode active material.

[0082] In one embodiment, the adhesive layer further comprises 5%-15% of a binder, and the amount of the binder added may be 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 15%, etc. Or it may be a range consisting of any two of the above values, for example, 5%-8%, 8%-10%, 10%-12%, 12%-15%, etc. The binder comprises at least one of polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylate resin. The selected binder is a binder originally used in the positive electrode active layer and the negative electrode active layer, which can enhance the viscosity of the adhesive layer while not easily causing side reactions with the electrolyte.

[0083] See also Figure 4 , Figure 4 Schematic diagram of the structure of the tape according to one or more embodiments. In one embodiment, the adhesive layer 43 includes an edge area 433 and a middle area 431, and the edge area 433 is at least located on two opposite sides of the middle area 431, and the acidic material and / or the adhesive are distributed in the edge area 433. The middle area 431 and the edge area 433 are relative concepts, which are only used to divide the area of ​​the tape and have no primary and secondary orientation. The electrolyte erosion of the tape starts from the edge. The use of acidic materials and adhesives to modify the adhesive layer in the edge area can slow down the speed of the electrolyte eroding into the adhesive layer. At the same time, the middle area still retains sufficient viscosity to improve the stability of the fixation.

[0084] In one embodiment, in the width direction (X direction shown in the figure), the length of the middle area 431 is L1, and the total length of the edge area 433 is L2, 0<L2 / L1<0.2. Among them, the edge area 433 is divided into multiple areas by the middle area 431, and the length of the edge area 433 is the sum of the lengths of each edge area, that is, L2=L21+L22. L1 / L2 can be 0.05, 0.08, 0.10, 0.12, 0.15, 0.17, 0.20, etc. Or it can be a range consisting of any two of the above values, for example, 0-0.20, 0.05-0.10, 0.10-0.15, 0.15-0.17, 0.17-0.20, etc. Through this arrangement, the risk of the adhesive being corroded and hydrolyzed by the electrolyte can be reduced while maintaining the bonding stability of the tape.

[0085] In one embodiment, the thickness of the base layer is 12-40 μm, for example, 12 μm, 15 μm, 18 μm, 22 μm, 28 μm, 32 μm, 35 μm, 38 μm, 40 μm, etc. Or it is a range consisting of any two of the above values, for example, 12-18 μm, 18-28 μm, 28-35 μm, 35-40 μm, etc. This configuration can improve the bonding stability of the tape.

[0086] In one embodiment, the thickness of the adhesive layer is 10-30 μm. For example, it can be 10 μm, 12 μm, 15 μm, 18 μm, 22 μm, 25 μm, 28 μm, 30 μm, etc. Or it can be a range consisting of any two of the above values, for example, 10-15 μm, 15-18 μm, 18-25 μm, 25-28 μm, 28-30 μm, etc. This setting can improve the bonding stability of the tape.

[0087] In the above embodiments, the provided adhesive tape has strong alkali resistance, good stability in alkali metal battery electrolyte, and is not easily corroded by the electrolyte. The resulting battery has strong mechanical stability and high cycle and storage performance.

[0088] In one embodiment, the tape is used to adhere and fix the electrode assembly, such as fixing the end of a wound electrode assembly; the tape is also used to protect the electrode tab weld mark; the tape can also be used to fix and connect multiple battery cells and bundle and fix the battery cells.

[0089] In one embodiment, when charging and discharging at 25°C and the internal pressure of the alkali metal battery cell reaches 0.35MPa, the number of cycles of the battery cell is greater than 200 (Cls). Optionally, the number of cycles is greater than 195, 190, 180, 170, 160, 155, etc. In this embodiment, the internal components of the battery cell are fixed by using the adhesive tape provided by the present application. The adhesive tape used is relatively stable in the alkaline electrolyte system, is not easy to hydrolyze, reduces the occurrence of side reactions, reduces the gas production of the battery, and improves the safety and cycle life of the battery.

[0090] In one embodiment, when stored at 25°C and the internal pressure of the alkali metal battery cell reaches 0.60 MPa, the storage days of the battery cell are greater than 360 days. Optionally, the storage days are greater than 320 days, 300 days, 280 days, 250 days, 200 days, 150 days, etc. In this embodiment, the internal components of the battery cell are fixed by using the tape provided by the present application. The tape used is relatively stable in the alkaline electrolyte system, is not easy to hydrolyze, reduces the occurrence of side reactions, reduces the gas production of the battery, and improves the safety and storage performance of the battery.

[0091] In one embodiment, the gas production of the alkali metal battery monomer is less than 0.06 ml / Ah / cycle when charging and discharging at 25°C. Optionally, it is less than 0.055 ml / Ah / cycle, less than 0.050 ml / Ah / cycle, less than 0.040 ml / Ah / cycle, and less than 0.030 ml / Ah / cycle. In this embodiment, by selecting a tape with more stable performance, the side reactions in the battery system are reduced, the amount of gas produced is reduced, and the safety and cycle life of the battery are improved.

[0092] In one embodiment, when stored at 25°C, the gas production of the alkali metal battery monomer is less than 0.04 ml / Ah / day. Optionally, less than 0.035 ml / Ah / day, less than 0.030 ml / Ah / day, less than 0.025 ml / Ah / day, less than 0.010 ml / Ah / day. In this embodiment, by selecting a tape with more stable performance, the side reactions in the battery system are reduced, the amount of gas produced is reduced, and the safety and cycle life of the battery are improved.

[0093] In some embodiments, the purpose of the electrochemical device of the present application is not particularly limited, and it can be used for any electronic device known in the prior art. The battery disclosed in the embodiment of the present application can be used for various energy storage systems using batteries as power supplies or using batteries as energy storage elements. That is, a kind of electric device is provided. In some embodiments, the electric device of the present application can be used for, but not limited to, notebook computers, pen-input computers, mobile computers, e-book players, portable phones, portable fax machines, portable copiers, portable printers, head-mounted stereo headphones, video recorders, LCD TVs, portable cleaners, portable CD players, mini-discs, transceivers, electronic notepads, calculators, memory cards, portable recorders, radios, backup power supplies, motors, cars, motorcycles, power-assisted bicycles, bicycles, ships, spacecraft, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, large-scale household batteries and lithium-ion capacitors, etc.

[0094] Electrical equipment can choose battery cells, battery modules or battery packs according to its usage requirements.

[0095] Please refer to Figure 5 , Figure 5 : is a schematic diagram of the structure of a vehicle according to one or more embodiments. The vehicle 1000 may be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may 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 may be provided at the bottom, the head or the tail of the vehicle 1000. The battery 100 may be used to power the vehicle 1000, for example, the battery 100 may be used as an operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300, and the controller 200 is used to control the battery 100 to power the motor 300, for example, for the starting, navigation and working power requirements of the vehicle 1000 during driving.

[0096] In some embodiments of the present application, the battery 100 can not only serve as an operating power source for the vehicle 1000, but also serve 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.

[0097] The beneficial effects of the present application are further illustrated below in conjunction with embodiments.

[0098] 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 the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present application and its applications. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0099] Example 1

[0100] 1) Preparation of tape

[0101] The ingredients of the adhesive layer in the tape include 10% EPDM rubber, 10% tackifying resin, 0.5% green pigment and 79.5% polyethylene terephthalate.

[0102] Add 10% thickening resin, 0.5% green pigment, 79.5% polyethylene terephthalate polymer powder into the mixing tank, mix the polymer powder and 10% adhesive EPDM rubber together and stir thoroughly, apply the mixed material to the surface of the PI base film, and use an oven to dry it after coating.

[0103] 2) Preparation of batteries

[0104] Preparation of positive electrode

[0105] The positive electrode active material NaFePO4, the conductive agent acetylene black, and the binder carboxymethyl cellulose are fully stirred and mixed in a proper amount of N-methylpyrrolidone (NMP) at a mass ratio of 95:2:3 to form a uniform positive electrode slurry; the positive electrode slurry is coated on the surface of the positive electrode current collector aluminum foil, and after drying, cold pressing, and die-cutting, a positive electrode sheet with a thickness of 200 μm is obtained.

[0106] Preparation of negative electrode

[0107] Prepare hard carbon and binder polyvinylidene fluoride (PVDF) with a mass ratio of 60:40, the Dv50 of the hard carbon is 500nm, dissolve the hard carbon and the binder in a solvent to obtain a conductive coating slurry, prepare a current collector (copper foil), and coat the conductive coating slurry on the current collector. After drying, the coating thickness is 2μm, and the negative electrode sheet is obtained through compaction and other processes.

[0108] Preparation of electrolyte

[0109] In an argon-filled glove box with a water content of <1 ppm, diethylene glycol dimethyl ether and tetrahydrofuran were mixed in a mass ratio of 1:3, sodium hexafluorophosphate (NaPF6) with a concentration of 1.0 mol / L was added, and after stirring evenly, an electrolyte was obtained.

[0110] Preparation of anode-free sodium metal batteries

[0111] The positive electrode sheet, separator, and negative electrode sheet prepared in the above steps are stacked in order, so that the separator is located between the positive electrode sheet and the negative electrode sheet and can isolate the positive electrode sheet from the negative electrode sheet; then the stacked components are wound to obtain an electrode assembly; the electrode assembly is set in a shell, and the electrolyte is injected after drying; after the formation, standing and other processes, a negative electrode-free sodium metal battery is obtained.

[0112] The difference between Comparative Example 1 and Examples 2-7 and Example 1 is that the composition and content of the adhesive in the tape are different, as shown in Table 1 for details.

[0113] Performance Test:

[0114] (1) Storage of gas production:

[0115] Arrange a pipeline along the sealing nail welding hole of the secondary battery prepared above. The diameter of the pipeline is the same as that of the sealing nail hole. The end of the pipeline is connected to the oil gauge. The battery is clamped with two aluminum plates. The initial clamping force is set to 3000N. Calibrate it three times, each time with an interval of 15 minutes; then fully charge the battery to 100% SOC. The temperature of all batteries must be monitored and the oil gauge pressure must be recorded.

[0116] (2) Circulation gas production:

[0117] Arrange a pipeline along the welding hole of the sealing nail for the secondary battery prepared above. The diameter of the pipeline is the same as that of the sealing nail hole. Connect the oil gauge along the end of the pipeline. The battery is clamped with two aluminum plates. The initial clamp force is set to 3000N and calibrated three times, each time at an interval of 15 minutes. Then the battery is charged and discharged at 1C / 1C. The temperature of all batteries must be monitored and the oil gauge pressure must be recorded.

[0118] Table 1 Condition parameters and performance parameters of each embodiment and comparative example

[0119]

[0120] Note: Content refers to the content of adhesive in the adhesive layer; Thickness refers to the thickness of the adhesive layer in the tape

[0121] Please refer to Table 1 and Figure 6 , Figure 6 Schematic diagram of gas production data of Example 1 and Comparative Example 1. The data show that when the adhesive is a rubber adhesive and a tert-butyl ester adhesive, the gas production of the battery is reduced, and the storage and cycle performance are improved.

[0122] The above description 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 present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. An alkali metal battery cell, characterized in that: include: Electrode assembly; an adhesive tape partially covering a surface of the electrode assembly; The adhesive tape includes an adhesive, and the adhesive includes one or more of a rubber adhesive and a tert-butyl ester adhesive.

2. The alkali metal battery cell according to claim 1, characterized in that: The rubber adhesive includes EPDM rubber; the tert-butyl ester adhesive includes one or more of tert-butyl acrylate and tert-butyl methacrylate.

3. The alkali metal battery cell according to claim 1 or 2, characterized in that: The adhesive tape comprises a base layer and an adhesive layer, wherein the adhesive layer is located on one side of the base layer, and comprises, by weight, 1%-15% of adhesive, 1%-15% of tackifying resin, 0.1%-10% of pigment, and 75%-95% of polyethylene terephthalate.

4. The alkali metal battery cell according to claim 3, characterized in that: The thickness of the base layer is 2-12 μm; and / or The thickness of the adhesive layer is 2-8 μm.

5. The alkali metal battery cell according to any one of claims 1 to 4, characterized in that: When charged and discharged at 25°C, when the internal pressure of the alkali metal battery cell reaches 0.35MPa, the number of cycles of the battery cell is greater than 200; and / or When stored at 25° C., when the internal pressure of the alkali metal battery cell reaches 0.60 MPa, the storage days of the battery cell are greater than 360 days.

6. The alkali metal battery cell according to any one of claims 1 to 5, characterized in that: When charged and discharged at 25°C, the gas production of the alkali metal battery monomer is less than 0.06 ml / Ah / cycle; and / or When stored at 25° C., the gas generation of the alkali metal battery monomer is less than 0.04 ml / Ah / day.

7. The alkali metal battery cell according to any one of claims 1 to 6, characterized in that: The electrolyte of the alkali metal battery monomer includes one or more solvents selected from chain ethers, ethylene glycol dimethyl ether and its derivatives, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, and cyclic ethers.

8. The alkali metal battery cell according to any one of claims 1 to 7, characterized in that: The positive electrode material of the alkali metal battery monomer includes one or more of a polyanion positive electrode material, a phosphate positive electrode material, a sulfate positive electrode material, a silicate positive electrode material, and a borate positive electrode material; and / or The negative electrode material of the alkali metal battery cell includes one or more of conductive carbon, graphite, hard carbon, and carbon nanotubes.

9. The alkali metal battery cell according to any one of claims 1 to 8, characterized in that: The negative electrode active material of the alkali metal battery cell is sodium metal.

10. The alkali metal battery cell according to any one of claims 1 to 9, characterized in that: The adhesive tape at least partially covers the electrode tab weld mark.

11. An alkali metal battery, characterized in that: The invention comprises a plurality of alkali metal battery cells according to any one of claims 1 to 10.

12. The alkali metal battery according to claim 11, characterized in that The alkali metal battery comprises an adhesive tape, and the adhesive tape is used for bonding and fixing adjacent alkali metal battery cells.

13. An electrical equipment, characterized in that: Comprising the alkali metal battery as claimed in claim 11 or 12.

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