An alkali metal battery cell, an alkali metal battery, and an electric device

Abstract

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

Description

Technical Field

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

[0002] With the continuous development of new energy technologies, power batteries are widely used in various consumer electronics products, electric vehicles, aerospace, and other fields. A battery includes a single cell, which in turn includes electrode components and an electrolyte. The electrode components include a positive electrode, a negative electrode, and a separator. To improve the stability of the components within a single cell, adhesive tape is typically used to fix them. However, when the tape is immersed in the electrolyte for extended periods, the adhesive is easily hydrolyzed and destroyed. This not only reduces the tape's bonding strength, leading to decreased battery mechanical stability, but may also cause side reactions, affecting the battery's cycle and storage performance. The above statements are for informational purposes only and do not necessarily constitute prior art. Summary of the Invention

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

[0004] To address the aforementioned technical problems, this application provides a technical solution: an alkali metal battery cell comprising an electrode assembly and an adhesive tape; the adhesive tape partially covers the surface of the electrode assembly; the adhesive tape includes an adhesive, which may be one or more of rubber-based adhesives and tert-butyl ester adhesives. In this embodiment, the selected rubber-based adhesive exhibits stable performance and strong alkali resistance, making it relatively stable in the alkali metal battery system and less prone to hydrolysis; the selected tert-butyl ester adhesive has a large steric hindrance of the tert-butyl group, making it less prone to hydrolysis in an alkaline environment. By selecting rubber-based adhesives and tert-butyl ester adhesives as the adhesive layer, the stability of the tape in the alkali metal battery system can be improved.

[0005] In one embodiment, the rubber-based adhesive includes ethylene propylene diene monomer (EPDM) rubber; the tert-butyl acrylate adhesive includes one or more of tert-butyl acrylate and tert-butyl methacrylate. In this embodiment, the selected EPDM rubber exhibits stable properties and strong alkali resistance, making it relatively stable in alkaline electrolyte systems and less prone to hydrolysis. The tert-butyl groups in the selected tert-butyl acrylate and tert-butyl methacrylate have significant steric hindrance, making the tert-butyl acrylate adhesive less prone to hydrolysis in alkaline environments. By selecting EPDM rubber, tert-butyl acrylate, and tert-butyl methacrylate as adhesives for the adhesive layer, the stability of the tape in the electrolyte can be improved.

[0006] In one embodiment, the tape includes a base layer and an adhesive layer, with the adhesive layer located on one side of the base layer. By weight, the adhesive layer comprises 1%-15% adhesive, 1%-15% tackifying resin, 0.1%-10% green pigment, and 75%-95% polyethylene terephthalate. This configuration enables the tape to have strong adhesion, improves the stability of the fixed structure, and is less prone to hydrolysis in the electrolyte. For example, the adhesive content can be 1%, 3%, 5%, 7%, 9%, 10%, 13%, 15%, etc. A higher adhesive content increases adhesive strength; however, excessive adhesive can lead to side reactions after prolonged immersion in the electrolyte, affecting the battery's cycle and storage performance.

[0007] In one embodiment, the thickness of the substrate is 2-12 μm; for example, it can be 2 μm, 4 μm, 6 μm, 8 μm, 10 μm, 12 μm, etc. The substrate can be a polyimide (PI) material. The substrate can provide support and adhesion for the adhesive, while protecting the adhesive and preventing it 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. A thicker adhesive layer can improve the bonding stability of the tape, but it will increase the total amount of adhesive and cause side reactions after immersion in electrolyte, affecting the cycle and storage performance of the battery; a thinner adhesive layer will lead to a decrease in adhesion.

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

[0010] In one embodiment, when alkali metal battery cells are stored at 25°C, the storage period of the battery cells exceeds 360 days when the internal pressure of the battery cells reaches 0.60 MPa. In this embodiment, by selecting a more stable adhesive tape, 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, under charge-discharge conditions at 25°C, the gas production of a single alkali metal battery cell is less than 0.06 ml / Ah / cycle. In this embodiment, by selecting a more stable tape, side reactions in the battery system are reduced, the amount of gas produced is decreased, and the battery's safety and cycle life are improved.

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

[0013] In one embodiment, the electrolyte of the alkali metal battery cell 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 production can be reduced.

[0014] In one embodiment, the cathode material of the alkali metal battery cell includes one or more of the following: polyanionic cathode materials, phosphate cathode materials, sulfate cathode materials, silicate cathode materials, and borate cathode materials. By selecting these types of electrode materials, the electrode materials exhibit good stability, fewer side reactions in the battery system, and reduced gas production in the battery.

[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 possess 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 performance and high capacity.

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

[0018] To address the aforementioned technical problems, another technical solution adopted in this application is to provide an alkali metal battery, comprising any of the aforementioned alkali metal battery cells. The resulting battery exhibits strong mechanical stability and high cycle and storage performance.

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

[0020] To address the aforementioned technical problems, another technical solution adopted in this application is to provide an electrical device comprising the aforementioned alkali metal battery. This electrical device possesses at least the same advantages as the battery, enhancing the safety of the device.

[0021] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

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

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

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

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

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

[0028] Figure 6 This is a schematic diagram of gas production data for 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 Cap; 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 Implementation

[0031] To make the objectives, technical solutions, and effects of this application clearer and more explicit, the embodiments of the technical solutions of this application will be described in detail below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of this application, and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0033] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces), unless otherwise explicitly specified.

[0034] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0035] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0036] Quantities, ratios, and other numerical values ​​are presented in range format in this document. It should be understood that this range format is for convenience and brevity and should be interpreted flexibly to include not only numerical values ​​explicitly specified as range limits, but also all individual numerical values ​​or subranges covered within the range, as if each numerical value and subrange were explicitly specified.

[0037] Unless otherwise specified, all steps of this application may 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 steps (b) and (a) performed sequentially, or steps (a) and (b) may be 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 steps (a), (c), and (b), or 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. However, lithium resources are limited and prices are rising, necessitating the development of new energy storage devices that are abundant in resources and inexpensive. To obtain high-capacity lithium-ion batteries, metallic materials with high storage capacity, such as silicon (4200 mAh / g) and tin (990 mAh / g), are used as negative electrode active materials through alloying with lithium. However, when metals such as silicon and tin are used as negative electrode active materials, their volume expands to approximately four times during charging with lithium alloying, and then contracts again during discharging. Due to the repeated large volume changes of the electrode components during charging / discharging, the active material gradually micronizes and detaches from the electrode, resulting in a rapid decrease in capacity and making it difficult to ensure stability and reliability.

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

[0040] This application provides an electrochemical device, which includes any device that performs an electrochemical reaction. Specific examples of such devices include alkali metal batteries, such as sodium metal batteries, lithium metal batteries, potassium metal batteries, etc.

[0041] Please refer to Figure 1 , Figure 1This is an exploded structural diagram of a battery according to one or more embodiments. The battery 100 includes a housing 10 and a battery cell 20, the battery cell 20 being housed within the housing 10. The housing 10 provides a accommodating space for the battery cell 20, and the housing 10 can adopt various structures. In some embodiments, the housing 10 may include a first portion 11 and a second portion 12, the first portion 11 and the second portion 12 overlapping each other, together defining a accommodating space for accommodating the battery cell 20. The second portion 12 may be a hollow structure with one open end, and the first portion 11 may be a plate-like structure, covering the open side of the second portion 12 so that the first portion 11 and the second portion 12 together define the accommodating space; alternatively, the first portion 11 and the second portion 12 may both be hollow structures with one open side, the open side of the first portion 11 covering the open side of the second portion 12. Of course, the housing 10 formed by the first portion 11 and the second portion 12 can be of various shapes, such as a cylinder, a cuboid, etc.

[0042] In battery 100, there can be multiple battery cells 20, which can be connected in series, parallel, or in a mixed manner. A mixed connection means that multiple battery cells 20 are connected in both series and parallel configurations. Multiple battery cells 20 can be directly connected in series, parallel, or in a mixed manner, and then the entire assembly of the multiple battery cells 20 is housed within the housing 10. Alternatively, battery 100 can also be composed of multiple battery cells 20 first connected in series, parallel, or in a mixed manner to form a battery module, and then multiple battery modules are connected in series, parallel, or in a mixed manner to form a whole, which is also housed within the housing 10. Battery 100 may also include other structures; for example, it may include a busbar component for electrical connection between the multiple battery cells 20.

[0043] Each battery cell 20 can be a secondary battery or a primary battery. The battery cell 20 can be cylindrical, flat, cuboid, or other shapes.

[0044] Please refer to Figure 2 , Figure 2 This is an exploded structural diagram of a battery cell according to one or more embodiments. Battery cell 20 refers to the smallest unit that makes up the battery. Figure 2 The battery cell 20 includes an end cap 21, a housing 22, an electrode assembly 23, and other functional components.

[0045] End cap 21 refers to a component that covers the opening of housing 22 to isolate the internal environment of battery cell 20 from the external environment. The shape of end cap 21 can be adapted to the shape of housing 22 to fit it. Optionally, end cap 21 can be made of a material with certain hardness and strength (such as aluminum alloy), so that end cap 21 is not easily deformed under pressure and impact, allowing battery cell 20 to have higher structural strength and improved safety performance. Functional components such as electrode terminals 21a can be provided on end cap 21. Electrode terminals 21a can be used for electrical connection with electrode assembly 23 to output or input electrical energy to battery cell 20. In some embodiments, end cap 21 can also be provided with a pressure relief mechanism for releasing internal pressure when the internal pressure or temperature of battery cell 20 reaches a threshold. The material of end cap 21 can also be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this application embodiment does not impose special limitations on this. In some embodiments, an insulating element may be provided on the inner side of the end cap 21. The insulating element can be used to isolate the electrical connection components within the housing 22 from the end cap 21 to reduce the risk of short circuits. For example, the insulating element may be made of plastic, rubber, etc.

[0046] The housing 22 is a component used to cooperate with the end cap 21 to form the internal environment of the battery cell 20. This internal environment can accommodate the electrode assembly 23, electrolyte, and other components. The housing 22 and the end cap 21 can be independent components. An opening can be provided on the housing 22, and the end cap 21 can be used to close the opening to form the internal environment of the battery cell 20. Alternatively, the end cap 21 and the housing 22 can be integrated. Specifically, the end cap 21 and the housing 22 can form a common connecting surface before other components are inserted into the housing. When it is necessary to encapsulate the interior of the housing 22, the end cap 21 closes the housing 22. The housing 22 can be of various shapes and sizes, such as cuboid, cylindrical, hexagonal prism, etc. Specifically, the shape of the housing 22 can be determined according to the specific shape and size of the electrode assembly 23. The material of the housing 22 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. This application embodiment does not impose any special limitations on this.

[0047] Electrode assembly 23 is the component in the battery cell 20 where electrochemical reactions occur. The casing 22 may contain one or more electrode assemblies 23. The electrode assembly 23 is mainly formed by winding or stacking positive and negative electrode plates, and typically a separator is provided between the positive and negative electrode plates. The portions of the positive and negative electrode plates containing active material constitute the main body of the electrode assembly, while the portions of the positive and negative electrode plates without active material each constitute a tab 23a. The positive and negative tabs may be located together at one end of the main body or separately at both ends of the main body. During the charging and discharging process of the battery, the positive and negative active materials react with the electrolyte, and the tabs 23a connect to the electrode terminals to form a current loop.

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

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

[0050] In one embodiment, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. 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 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 the following: polyanionic positive electrode materials, phosphate-based positive electrode materials, sulfate-based positive electrode materials, silicate-based positive electrode materials, and borate-based positive electrode materials. For example, among the positive electrode active materials for sodium metal batteries, polyanionic compounds are primarily based on phosphoric acid and fluorophosphoric acid. Among phosphoric acid-based compounds, Na... x1 Fe y1 P m1 O n1Sodium iron phosphate has attracted widespread attention due to its high capacity and voltage platform. For example, sodium iron phosphate, with its high capacity, can provide high energy density for sodium metal batteries; sodium iron pyrophosphate, with its high voltage platform, can provide high 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 and 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 lithium metal batteries can 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), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated 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 selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0054] A negative electrode typically includes a negative current collector, or includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector, the negative electrode film layer including a negative electrode active material.

[0055] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode film layer can be disposed on either 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, copper foil may be used as the metal foil. The composite current collector may include a polymeric material substrate and a metal layer formed on at least one surface of the polymeric material substrate. The composite current collector can be obtained by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymeric material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

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

[0058] In one embodiment, the negative electrode active material may be a negative electrode active material known in the art for use in sodium batteries. As an example, the negative electrode active material may include at least one of the following materials: carbon-based materials, alloy materials, titanium-based materials, sodium metal, carbon-based materials deposited with sodium metal, composite materials containing sodium metal, alloy materials containing sodium metal, etc. The aforementioned carbon-based materials include, but are not limited to, graphite, soft carbon, hard carbon, carbon microspheres, carbon fibers, carbon nanotubes, and conductive carbon. The aforementioned alloy materials include, but are not limited to, sodium-tin alloys, sodium-germanium alloys, and sodium-antimony alloys. The aforementioned titanium-based materials include, but are not limited to, titanium dioxide, titanates, and titanium phosphates. This 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 alloys, potassium metal, or potassium alloys.

[0059] The electrolyte acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific restrictions on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte can be liquid, gel, or entirely solid.

[0060] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution 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(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium difluorooxalateborate, lithium tetrafluoroborate, and lithium trifluoromethanesulfonate.

[0062] In one embodiment, the solvent includes one or more solvents selected from chain ethers, diethylene glycol dimethyl ether and its derivatives, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, and cyclic ethers. Specifically, it includes dimethyl ether (DME), diethylene glycol dimethyl ether, diethylene glycol diethyl ether, tetraethylene glycol dimethyl ether, 2,2,2,2-trifluoroethyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, methyltrifluoroethyl 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 also include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

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

[0065] In one embodiment, the material of the separator can be selected from at least one of glass fiber, nonwoven 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.

[0066] In one embodiment, large-area tape is often used in alkali metal battery cells to bond and fix electrode plates, tabs, etc. That is, alkali metal battery cells also include tape, which partially covers the surface of the electrode assembly for fixing the electrode assembly. For example, it can be used as terminating tape to fix the ends of electrode plates in a wound battery; it can also be used as protective tape to cover the tab solder marks and protect them. Furthermore, it can also be used to fix and connect two adjacent battery cells.

[0067] Currently, commonly used adhesive tapes contain polymethyl methacrylate (PMMA), polyethyl acrylate (PEMA), polypropyl acrylate (PPA), polybutyl acrylate (butyl acrylate), polypentyl acrylate (PMA), and polyoctyl acrylate (OCA). However, the electrolyte system of alkali metal batteries is alkaline. When the tape is immersed in the electrolyte for a long time, these esters are prone to saponification under strongly alkaline conditions, leading to hydrolysis, as detailed below:

[0068]

[0069] Hydrolysis not only causes the tape to turn black but also generates a large amount of gas, affecting the cycle and storage performance of individual battery cells. Blue adhesive will develop bubbles and easily turn black over time.

[0070] Please see Figure 3 , Figure 3 This is a schematic diagram of the structure of an adhesive tape according to one or more embodiments. This application provides an adhesive tape 40 for alkali metal batteries. The tape 40 includes a base layer 41 and an adhesive layer 43. The adhesive layer 43 is located on one side of the base layer 41 and includes an adhesive, which includes one or more of rubber-based adhesives and tert-butyl ester adhesives.

[0071] In this embodiment, the selected rubber-based adhesive exhibits stable performance and strong alkali resistance, making it relatively stable in alkali metal battery systems and less prone to hydrolysis. The selected tert-butyl ester adhesive has significant steric hindrance of the tert-butyl group, further reducing its susceptibility to hydrolysis in alkaline environments. By selecting rubber-based and tert-butyl ester adhesives as the adhesive layer, the stability of the adhesive layer in alkali metal battery systems can be improved. The tape provided in this application shows no significant surface changes after prolonged use, demonstrating stable performance.

[0072] In one embodiment, the rubber-based adhesive includes ethylene propylene diene monomer (EPDM) rubber; the tert-butyl ester-based adhesive includes one or more of tert-butyl acrylate and tert-butyl methacrylate.

[0073] In this embodiment, the selected EPDM rubber exhibits stable performance and strong alkali resistance, making it relatively stable in the alkaline electrolyte system of alkali metal batteries and less prone to hydrolysis. The tert-butyl groups in the selected tert-butyl acrylate and tert-butyl methacrylate have significant steric hindrance, further reducing the likelihood of hydrolysis in alkaline environments. By selecting EPDM rubber, tert-butyl acrylate, and tert-butyl methacrylate as adhesives for the adhesive layer, the stability of the adhesive layer in the electrolyte can be improved.

[0074] In one embodiment, the adhesive layer comprises, by weight parts, 1%-15% adhesive, 1%-15% tackifying resin, 0.1%-10% green pigment, and 75%-95% polyethylene terephthalate. This configuration enables the tape to have strong adhesion, improves the stability of the fixed structure, and is less prone to hydrolysis 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, and hydrogenated / modified resin; for example, at least one of hydrogenated petroleum resin, hydrogenated rosin resin, and hydrogenated terpene resin.

[0076] In one embodiment, the adhesive content can be 1%, 3%, 5%, 7%, 9%, 11%, 13%, 15%, etc., or a range of any two of the above values, such as 1%-3%, 3%-5%, 5%-7%, 7%-11%, 11%-15%, etc. By controlling the adhesive content, the adhesiveness of the tape can be adjusted. While maintaining adhesiveness, the use of adhesive can be minimized to reduce 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 of any two of the above values, such as 1%-3%, 3%-5%, 5%-7%, 7%-11%, 11%-15%, etc. The tackifying resin includes room-temperature solid tackifying resin and room-temperature liquid tackifying resin. The room-temperature solid tackifying resin is rosin, terpene resin, C5 or C9 petroleum resin, or hydrogenated / modified resin.

[0078] The content of green pigment can be 0.1%, 0.5%, 1%, 3%, 5%, 7%, 9%, 10%, etc., or a range of any two of the above values, such as 0.1%-0.5%, 0.5%-1%, 1%-3%, 3%-5%, 5%-7%, 7%-10%, etc. Green pigments can be cobalt green, zinc oxide, zirconium oxide, etc.

[0079] The content of poly(ethylene terephthalate) can be 75%, 80%, 85%, 90%, 95%, etc., or a range of any two of the above values, such as 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 acidic material added can 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 a range of any two of the above values, such as 1%-3%, 3%-5.5%, 5.5%-7%, 7%-10%, etc. By adding the acidic material, the alkali in the electrolyte can be neutralized when the adhesive layer is eroded by the electrolyte, reducing the risk of hydrolysis of the adhesive when exposed to 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 ammonium polyphosphate material can also have a flame-retardant effect, reducing the risk of battery cell ignition. The selected 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 water generated in the electrolyte to form stable compounds, playing a "water-removing" role and reducing the risk of water corrosion of the electrode active materials.

[0082] In one embodiment, the adhesive layer further includes 5%-15% of a binder. The amount of binder added can 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 a range of any two of the above values, such as 5%-8%, 8%-10%, 10%-12%, 12%-15%, etc. The binder includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin. The selected binder is originally used in the positive electrode active layer and the negative electrode active layer, which can enhance the adhesion of the adhesive layer while not easily causing side reactions with the electrolyte.

[0083] Please see Figure 4 , Figure 4 This is a schematic diagram of the structure of an adhesive tape according to one or more embodiments. In one embodiment, the adhesive layer 43 includes an edge region 433 and a middle region 431, with the edge region 433 located at least on opposite sides of the middle region 431. An acidic material and / or adhesive is distributed in the edge region 433. The middle region 431 and the edge region 433 are relative concepts, used only to divide the tape into regions, and do not indicate primary or secondary regions. The erosion of the tape by the electrolyte begins from the edge. Modifying the adhesive layer in the edge region using acidic materials and adhesives can slow down the rate at which the electrolyte erodes into the adhesive layer, while the middle region still retains sufficient tack, improving the stability of the fixation.

[0084] In one embodiment, in the width direction (X direction shown in the figure), the length of the intermediate region 431 is L1, and the total length of the edge regions 433 is L2, where 0 < L2 / L1 < 0.2. The edge regions 433 are divided into multiple areas by the intermediate region 431, and the length of the edge region 433 is the sum of the lengths of all the edge regions, i.e., L2 = L21 + L22. L1 / L2 can be 0.05, 0.08, 0.10, 0.12, 0.15, 0.17, 0.20, etc., or a range consisting of any two of the above values, such as 0-0.20, 0.05-0.10, 0.10-0.15, 0.15-0.17, 0.17-0.20, etc. This arrangement reduces the risk of the adhesive being eroded and hydrolyzed by the electrolyte while maintaining the adhesive stability of the tape.

[0085] In one embodiment, the thickness of the base layer is 12-40 μm; for example, it can be 12 μm, 15 μm, 18 μm, 22 μm, 28 μm, 32 μm, 35 μm, 38 μm, 40 μm, etc., or a range consisting of any two of the above values, such as 12-18 μm, 18-28 μm, 28-35 μm, 35-40 μm, etc. This setting can improve the adhesive 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 a range consisting of any two of the above values, such as 10-15 μm, 15-18 μm, 18-25 μm, 25-28 μm, 28-30 μm, etc. This setting improves the adhesive stability of the tape.

[0087] In the above embodiments, the provided 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 electrode assemblies, such as fixing the ends of a wound electrode assembly; the tape is also used to protect the tab solder marks; the tape can also be used to fix and connect multiple battery cells or to bundle and fix battery cells.

[0089] In one embodiment, when charged and discharged at 25°C, the internal pressure of the alkali metal battery cell reaches 0.35 MPa, and the number of cycle times of the battery cell is greater than 200 cycles (Cls). Optionally, the number of cycle times 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 tape provided in this application. The tape used is relatively stable in the alkaline electrolyte system, not easily hydrolyzed, reducing the occurrence of side reactions, resulting in less gas production in the battery, and improving the safety and cycle life of the battery.

[0090] In one embodiment, when stored at 25°C, the internal pressure of the alkali metal battery cell reaches 0.60 MPa, and the storage period of the battery cell is greater than 360 days. Optionally, the storage period is 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 in this application. The tape used is relatively stable in the alkaline electrolyte system, not easily hydrolyzed, reducing the occurrence of side reactions, resulting in less gas production in the battery, and improving the safety and storage performance of the battery.

[0091] In one embodiment, under charge-discharge conditions at 25°C, the gas production of a single alkali metal battery cell is less than 0.06 ml / Ah / cycle. Optionally, it is less than 0.055 ml / Ah / cycle, less than 0.050 ml / Ah / cycle, less than 0.040 ml / Ah / cycle, or less than 0.030 ml / Ah / cycle. In this embodiment, by selecting a more stable tape, side reactions in the battery system are reduced, the amount of gas produced is reduced, and the battery safety and cycle life are improved.

[0092] In one embodiment, when stored at 25°C, the gas production of the alkali metal battery cell is less than 0.04 ml / Ah / day. Optionally, it is less than 0.035 ml / Ah / day, less than 0.030 ml / Ah / day, less than 0.025 ml / Ah / day, or less than 0.010 ml / Ah / day. In this embodiment, by selecting a more stable tape, 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 application of the electrochemical device of this application is not particularly limited, and it can be used in any electronic device known in the prior art. The battery disclosed in the embodiments of this application can be used in electrical devices that use batteries as a power source or in various energy storage systems that use batteries as energy storage elements. That is, an electrical device is provided. In some embodiments, the electrical device of this application can be used in, but is not limited to, laptops, pen input computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, headsets, video recorders, LCD TVs, portable cleaners, portable CD players, mini CDs, transceivers, electronic notebooks, calculators, memory cards, portable recorders, radios, backup power supplies, motors, automobiles, motorcycles, electric bicycles, bicycles, ships, spacecraft, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, household large-capacity batteries and lithium-ion capacitors, etc.

[0094] Electrical equipment can be equipped with individual battery cells, battery modules, or battery packs depending on its usage requirements.

[0095] Please refer to Figure 5 , Figure 5 This is a schematic diagram of a vehicle according to one or more embodiments. The vehicle 1000 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid electric vehicle, or a range-extended electric vehicle, etc. A battery 100 is disposed inside the vehicle 1000, and the battery 100 can be located at the bottom, front, or rear of the vehicle 1000. The battery 100 can be used to power the vehicle 1000; for example, the battery 100 can serve as the operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to supply power to the motor 300, for example, to meet the power requirements of the vehicle 1000 during startup, navigation, and driving.

[0096] In some embodiments of this application, the battery 100 can not only serve as the operating power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0097] The beneficial effects of this application are further illustrated below with reference to the embodiments.

[0098] To make the technical problems, technical solutions, and beneficial effects solved by the embodiments of this application clearer, the following will provide a more detailed description in conjunction with the embodiments and accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its applications. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0099] Example 1

[0100] 1) Preparation of adhesive tape

[0101] The adhesive layer of the tape consists of 10% EPDM rubber, 10% tackifying resin, 0.5% green pigment, and 79.5% poly(ethylene terephthalate).

[0102] Add 10% tackifying resin, 0.5% green pigment, and 79.5% polyethylene terephthalate polymer powder to a mixing tank. Mix the polymer powder and 10% EPDM rubber binder together and stir thoroughly. Coat the mixed material onto the surface of the PI base film and dry it in an oven after coating.

[0103] 2) Battery manufacturing

[0104] Preparation of positive electrode sheet

[0105] The positive electrode active material NaFePO4, the conductive agent acetylene black, and the binder carboxymethyl cellulose were thoroughly mixed in an appropriate amount of N-methylpyrrolidone (NMP) at a mass ratio of 95:2:3 to form a uniform positive electrode slurry. The positive electrode slurry was 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 was obtained.

[0106] Preparation of negative electrode sheet

[0107] Prepare hard carbon and binder polyvinylidene fluoride (PVDF) in a mass ratio of 60:40. The Dv50 of the hard carbon is 500 nm. Dissolve the hard carbon and binder in a solvent to obtain a conductive coating slurry. Prepare a current collector (copper foil). Coat the conductive coating slurry onto the current collector. After drying, the coating thickness is 2 μm. Obtain the negative electrode sheet through processes such as compaction.

[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 at a mass ratio of 1:3, and sodium hexafluorophosphate (NaPF6) with a concentration of 1.0 mol / L was added. After stirring evenly, an electrolyte was obtained.

[0110] Preparation of sodium metal batteries without negative electrodes

[0111] The positive electrode, separator, and negative electrode obtained in the above steps are stacked in sequence, so that the separator is between the positive and negative electrode and can isolate the positive and negative electrode; then the stacked components are wound to obtain an electrode assembly; the electrode assembly is placed in the housing, dried and injected with electrolyte; after formation, settling and other processes, a sodium metal battery without a negative electrode is obtained.

[0112] The difference between Comparative Example 1 and Examples 2-7 and Example 1 lies in the composition and content of the adhesive in the tape, as detailed in Table 1.

[0113] Performance testing:

[0114] (1) Gas generation during storage:

[0115] Arrange the secondary battery prepared above along the sealing nail welding hole with a pipe diameter that is the same as the sealing nail hole. Connect the oil gauge to the end of the pipe. Use two aluminum plates to clamp the battery. Set the initial clamping force to 3000N and calibrate it three times with a 15-minute interval between each time. Then fully charge the battery to 100% SOC. Monitor the temperature of all batteries and record the oil gauge pressure.

[0116] (2) Circulating gas production:

[0117] Arrange the secondary battery prepared above along the sealing nail welding hole to form a pipe with the same pipe diameter as the sealing nail hole. Connect the oil gauge to the end of the pipe. Use two aluminum plates to clamp the battery. Set the initial clamping force to 3000N and calibrate it three times with a 15-minute interval between each time. Then charge and discharge the battery at 1C / 1C. Monitor the temperature of all batteries and record the oil gauge pressure.

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

[0119]

[0120] Note: Content refers to the amount 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 This is a schematic diagram of gas production data for Example 1 and Comparative Example 1. The data shows that when the adhesive is a rubber-based or tert-butyl ester-based adhesive, the gas production of the battery is reduced, and the storage and cycle performance is improved.

[0122] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. An alkali metal battery cell, characterized in that, include: Electrode assembly; Adhesive tape, partially covering the surface of the electrode assembly; The tape includes a base layer and an adhesive layer, the adhesive layer being located on one side of the base layer. By weight, the adhesive layer includes 1%-15% adhesive, 1%-15% tackifying resin, 0.1%-10% pigment, and 75%-95% poly(ethylene terephthalate). The adhesive is a tert-butyl ester adhesive, which includes one or more of tert-butyl acrylate or tert-butyl methacrylate.

2. The alkali metal battery cell according to claim 1, 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.

3. The alkali metal battery cell according to any one of claims 1 to 2, characterized in that, When charged and discharged at 25°C, the internal pressure of the alkali metal battery cell reaches 0.35 MPa, and the number of cycles of the battery cell is greater than 200; and / or When stored at 25°C, the alkali metal battery cell has an internal pressure of 0.60 MPa and can be stored for more than 360 days.

4. The alkali metal battery cell according to any one of claims 1 to 3, characterized in that, Under charge-discharge conditions of 25°C, the gas production rate of the alkali metal battery cell is less than 0.06 ml / Ah / cycle; and / or When stored at 25°C, the gas production of the alkali metal battery cell is less than 0.04 ml / Ah / day.

5. The alkali metal battery cell according to any one of claims 1 to 4, characterized in that, The electrolyte of the alkali metal battery cell includes one or more solvents selected from chain ethers and cyclic ethers.

6. The alkali metal battery cell according to any one of claims 1 to 5, characterized in that, The cathode material of the alkali metal battery cell includes one or more of the following: polyanionic cathode materials, phosphate cathode materials, sulfate cathode materials, silicate cathode materials, and borate cathode materials; 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.

7. The alkali metal battery cell according to any one of claims 1 to 6, characterized in that, The negative electrode active material of the alkali metal battery cell is sodium metal.

8. The alkali metal battery cell according to any one of claims 1 to 7, characterized in that, The tape at least partially covers the electrode tab solder marks.

9. An alkali metal battery, characterized in that, It includes multiple alkali metal battery cells as described in any one of claims 1 to 8.

10. An electrical appliance, characterized in that, Including the alkali metal battery as described in claim 9.

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