An electrode assembly, a battery, and an electronic device

Abstract

An electrode assembly (100), a battery, and an electronic device. The electrode assembly (100) is wound by a first pole piece (a), a second pole piece (c), and a separator (b), wherein the separator (b) is disposed between the first pole piece (a) and the second pole piece (c); the electrode assembly (100) includes a planar region (10) and bending regions (20) located on both sides of the planar region (10), and an expansion material layer containing an expandable material is disposed between layers of the bending regions (20). An expansion material layer containing an expandable material is disposed between layers of the bending regions (20). The expandable material in the expansion material layer can be expanded through a certain inducing behavior, so as to fill the gap between the pole pieces in the bending regions (20), thereby improving the consistency of the battery interface.

Description

Technical Field

[0001] Embodiments of the present application relate to the technical field of batteries, and in particular, to an electrode assembly, a battery, and an electronic device. Background Art

[0002] A battery is a device that converts external energy into electrical energy and stores it internally to supply power to external devices when needed, and is increasingly widely used in fields such as consumer electronics, aerospace, energy storage, and new energy vehicles.

[0003] In the process of implementing the present application, the inventors found that at least the following problems exist in the related art: In the existing wound-type battery, since the gap between the electrode sheets in the bent region of the wound electrode core is larger than the gap between the electrode sheets in the flat region, there are differences in the battery interfaces between the bent region and the flat region. As a result, when harsh usage conditions occur, the battery interface in the bent region is more likely to be damaged, affecting the cycle life of the battery. Summary of the Invention

[0004] Embodiments of the present application aim to provide an electrode assembly, a battery, and an electronic device with better battery interface consistency and higher battery stability.

[0005] To solve the above technical problems, one technical solution adopted in the embodiments of the present application is: to provide an electrode assembly, which is wound by a first electrode sheet, a second electrode sheet, and a separator, wherein the separator is disposed between the first electrode sheet and the second electrode sheet;

[0006] The electrode assembly includes a flat region and bent regions on both sides of the flat region, and an expansion material layer is disposed between layers in the bent regions, and the expansion material layer contains an expandable material.

[0007] In some embodiments, the expansion material layer is a liquid-absorbing and expanding adhesive paper.

[0008] In some embodiments, the liquid-absorbing and expanding adhesive paper includes a first base material and a first glue layer disposed on the first base material, and the first base material and / or the first glue layer contains a liquid-absorbing and expanding material.

[0009] In some embodiments, the liquid-absorbing and expanding material includes at least one of polycaprolactam, sodium polyacrylate, and lithium polyacrylate.

[0010] In some embodiments, if the first base material includes the liquid-absorbing and expanding material, the weight ratio of the liquid-absorbing and expanding material in the first base material is 1 / 10 to 1 / 2;

[0011] If the first glue layer includes the liquid-absorbing and expanding material, the weight ratio of the liquid-absorbing and expanding material in the first glue layer is 1 / 10 to 1 / 5.

[0012] In some embodiments, the expansion material layer is a heat-expandable adhesive tape.

[0013] In some embodiments, the heat-expandable adhesive tape includes a second substrate and a second adhesive layer disposed on the second substrate, and the second substrate and / or the second adhesive layer contains a heat-expandable material.

[0014] In some embodiments, the heat-expandable material is a polymer material with a coefficient of thermal expansion greater than (1*10E-4) m / mK.

[0015] In some embodiments, the polymer material includes at least one of polycaprolactam, ethylene-ethyl acrylate, and cellulose acetate.

[0016] In some embodiments, if the second substrate includes the heat-expandable material, the weight ratio of the heat-expandable material in the second substrate is 1 / 10 to 1 / 2;

[0017] If the second adhesive layer includes the heat-expandable material, the weight ratio of the heat-expandable material in the second adhesive layer is 1 / 10 to 1 / 5.

[0018] In some embodiments, the expansion material layer is a first electrically energized expansion material layer, and the first electrically energized expansion material layer is coated on the first surface of the first electrode tab, and the first electrically energized expansion material layer contains an electrically energized expansion material.

[0019] In some embodiments, a second electrically energized expansion material layer is disposed between the planar regions, and the second electrically energized expansion material layer is coated on the first surface of the first electrode tab. The first electrically energized expansion material layer and the second electrically energized expansion material layer are of an integral structure and include the same electrically energized expansion material.

[0020] In some embodiments, the first surface is the surface of the first electrode tab away from the center of the electrode assembly.

[0021] In some embodiments, the electrically energized expansion material contains a Si-based material or a Sn-based material.

[0022] In some embodiments, the Si-based material or the Sn-based material is a material with a first efficiency lower than 70%.

[0023] In some embodiments, the thickness of the first electrically energized expansion material layer is less than 10% of the film thickness of the first electrode tab.

[0024] An embodiment of the present application also provides a battery, including: a housing; the above-mentioned electrode assembly, and the electrode assembly is disposed in the housing.

[0025] An embodiment of the present application further provides an electronic device, including: the above-mentioned battery.

[0026] In the embodiment of the present application, an expansion material layer containing an expandable material is provided between layers in the bending area of the electrode assembly. Due to the expansion of the expandable material, the expansion material layer expands, thereby filling the gap between the electrode sheets in the bending area and improving the consistency of the battery interface. Description of the Drawings

[0027] One or more embodiments are exemplarily illustrated by pictures in the corresponding drawings. These exemplary illustrations do not limit the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements. Unless otherwise stated, the drawings in the figures do not constitute a scale limitation.

[0028] Figure 1 It is a schematic structural diagram of an embodiment of the electrode assembly of the present application;

[0029] Figure 2a It is a schematic structural diagram of an embodiment of the electrode assembly of the present application;

[0030] Figure 2b It is a schematic structural diagram of an embodiment of the electrode assembly of the present application;

[0031] Figure 2c It is a schematic structural diagram of an embodiment of the electrode assembly of the present application;

[0032] Figure 3 It is a schematic structural diagram of the liquid-absorbing and expanding adhesive tape in an embodiment of the electrode assembly of the present application;

[0033] Figure 4 It is a flowchart of an embodiment of the preparation method of the electrode assembly of the present application;

[0034] Figure 5 Schematic structural diagram of the heated expanding adhesive tape in an embodiment of the electrode assembly of the present application;

[0035] Figure 6 It is a schematic structural diagram of the first electrode sheet in an embodiment of the electrode assembly of the present application;

[0036] Figure 7 It is a schematic structural diagram of the first electrode sheet in an embodiment of the electrode assembly of the present application;

[0037] Figure 8 It is a schematic structural diagram of an embodiment of the battery of the present application. Detailed Embodiments

[0038] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the following will clearly and completely describe the technical solutions in the embodiments of this application with reference to the accompanying drawings in the embodiments of this application. Apparently, the described embodiments are some, but not all, of the embodiments of this application. It should be understood that the specific embodiments described herein are only used to explain this application and are not used to limit this application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of this application without creative efforts shall fall within the scope of protection of this application.

[0039] It should be noted that when an element is expressed as "fixed to" another element, it can be directly on the other element, or there can be one or more intermediate elements therebetween. When an element is expressed as "connected to" another element, it can be directly connected to the other element, or there can be one or more intermediate elements therebetween. The terms "vertical", "horizontal", "left", "right", and similar expressions used in this specification are only for the purpose of illustration.

[0040] In addition, the technical features involved in the various embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0041] A wound electrode assembly is generally formed by winding a first electrode sheet and a second electrode sheet with opposite polarities, and a separator is provided between the first electrode sheet and the second electrode sheet. Figure 1 A structure of the wound electrode assembly is shown. In Figure 1 the shown structure, the electrode assembly 100 includes a first electrode sheet a, a separator b, and a second electrode sheet c. Among them, the separator b is disposed between the first electrode sheet a and the second electrode sheet c. After the first electrode sheet a, the separator b, and the second electrode sheet c are wound, a planar region 10 and bent regions 20 located on both sides of the planar region 10 are formed. Among them, the first electrode sheet can be an anode electrode sheet, and the second electrode sheet is a cathode electrode sheet; correspondingly, the first electrode sheet can be a cathode electrode sheet, and the second electrode sheet is an anode electrode sheet. Exemplarily, the following will all take the first electrode sheet as the anode electrode sheet and the second electrode sheet as the cathode electrode sheet as an example for illustration.

[0042] In the current wound electrode assembly, since the gap between the electrode sheets in the bent region 20 is larger than the gap between the electrode sheets in the planar region 10, there are differences in the battery interfaces between the bent region 20 and the planar region 10. During the cyclic use of the battery, the differences in the interfaces will cause the use window of the bent region to be worse than that of the planar region. Furthermore, when severe usage conditions occur, the battery interface in the bent region is more likely to be damaged, affecting the service life or other performance of the battery.

[0043] In order to improve the consistency of the battery interface and the stability of the battery, the embodiment of the present application sets an expansion material layer containing expandable material between the layers of the bending region (i.e., inside the bending region). The expandable material in the expansion material layer can be expanded through certain induced behaviors, thereby filling the gap between the pole pieces in the bending region to improve the consistency of the battery interface.

[0044] Among them, the wound electrode assembly is such as a wound lithium-ion battery cell. In addition to the wound lithium-ion battery cell, the solution provided in the embodiment of the present application is also applicable to other wound electrode assemblies.

[0045] In some embodiments, the expansion material layer may use liquid-absorbing expansion tape, which contains liquid-absorbing expansion material. The liquid-absorbing expansion material expands after absorbing liquid, generating stress, thereby squeezing the pole pieces in the bending area and reducing the gap between the pole pieces.

[0046] The liquid-absorbing swelling adhesive tape can be pasted to any suitable position inside the bending area 20, such as on the anode electrode sheet, the diaphragm and / or the cathode electrode sheet inside the bending area 20. It can be set on one side or both sides of the anode electrode sheet, the diaphragm and / or the cathode electrode sheet. When it is set on one side, it can be set on the side facing the center of the electrode assembly or on the side away from the center of the electrode assembly. When it is set on the side facing the center of the electrode assembly, the stress generated by the expansion of the expandable material is from the inside to the outside, and the extrusion effect is better.

[0047] Figure 2a The sticking positions of the liquid swelling adhesive tape are schematically shown, wherein 21a is the negative electrode single-sided film area inside the bending area (the negative electrode corresponds to the anode in the battery, and the positive electrode corresponds to the cathode), 21b is the positive electrode empty foil area, 21c is the negative electrode empty foil area, and 21d is the positive electrode film area. The liquid swelling adhesive tape can be stuck to one or more of the above sticking positions. Figure 2b The schematic diagram shows that the liquid-swelling adhesive tape 21 is pasted on the negative electrode single-sided film area 21a. Figure 2c A schematic diagram showing the liquid swelling adhesive tape 21 being pasted on the positive electrode empty foil area 21b is shown.

[0048] In one embodiment, if Figure 3 As shown, the liquid-swellable adhesive tape includes a first substrate 212 and a first glue layer 211 disposed on the first substrate 212. The liquid-swellable material can be added to the first substrate 212 or to the first glue layer 211. Of course, the liquid-swellable material can also be added to both the first substrate 212 and the first glue layer 211.

[0049] Specifically, in some embodiments, the liquid-absorbing swelling material includes at least one of polycaprolactam, sodium polyacrylate and lithium polyacrylate. Polymer materials such as polycaprolactam, sodium polyacrylate and lithium polyacrylate can absorb small molecule solvents into the crystal structure by utilizing the polyanion characteristics in the crystal structure. When the above polymer materials are added to the liquid-absorbing swelling adhesive tape, when the electrolyte is injected, small molecule solvents such as ethylene carbonate (EC) can be absorbed by the above polymer materials. After the polymer absorbs the liquid, the volume expands, thereby squeezing the pole pieces in the bending area and reducing the gap between the pole pieces.

[0050] The above-mentioned polymer material is stable in an acidic or alkaline environment, will not produce side reactions with the electrolyte, has a stable structure, exists stably within the operating voltage range of the battery, and can significantly change in volume after absorbing liquid; moreover, due to the stress between molecules, the solvent molecules will not be released in reverse when under pressure, but when the concentration of solvent molecules in the electrolyte is lower than that in the polymer, the polymer will actively release the solvent molecules, thereby achieving the effect of retaining the electrolyte.

[0051] In one embodiment, if the liquid-absorbing and swelling material is added to the first substrate 212, the weight ratio of the liquid-absorbing and swelling material in the first substrate 212 is preferably maintained at 1 / 10 to 1 / 2; if the liquid-absorbing and swelling material is added to the first glue layer, the weight ratio of the liquid-absorbing and swelling material in the first glue layer is preferably maintained at 1 / 10 to 1 / 5.

[0052] The electrode assembly comprising the liquid-swelling adhesive tape may be prepared by any suitable preparation method, and one preparation method is described below by way of example. Figure 4 As shown, the details are as follows:

[0053] 101: coating a first material on a current collector of a first pole piece once, and coating a second material on a current collector of a second pole piece once, wherein the first pole piece, the diaphragm, and the second pole piece each include at least one first position.

[0054] Anode material is coated on the current collector of the anode electrode sheet, and cathode material is coated on the current collector of the cathode electrode sheet. The first position is used to set the expansion material layer, and the first position can be set in the negative electrode single-sided film area 21a, the positive electrode empty foil area 21b, the negative electrode empty foil area 21c or the positive electrode film area 21d. The plane area and the bending area of ​​the wound electrode assembly need to be estimated in advance according to the size of the anode electrode sheet, the diaphragm or the cathode electrode sheet, so that the first position is located in the bending area. Figure 2a , Figure 2b and Figure 2c Several possible positions of the first position are shown.

[0055] The anode material is, for example, artificial graphite or natural graphite, and the cathode material is, for example, ternary polymer, lithium cobalt oxide or lithium iron phosphate.

[0056] 102: A swelling material layer is provided at at least one of the first positions of the first electrode sheet after the first coating, the separator, and / or the second electrode sheet after the first coating.

[0057] When the swelling material layer uses a liquid-absorbing swelling adhesive tape, the liquid-absorbing swelling adhesive tape is pasted at one or more first positions. Among them, a liquid-absorbing swelling adhesive tape can be obtained by adding a liquid-absorbing swelling material to the base material and / or the glue layer of the existing adhesive tape.

[0058] 103: The first electrode sheet, the separator, and the second electrode sheet are stacked in sequence to form a stacked sheet.

[0059] 104: The stacked sheet is wound to form an electrode assembly, and the first electrode sheet, the separator, and the second electrode sheet in the electrode assembly each include at least one plane and at least one bent surface.

[0060] After winding the stacked sheet, Figure 1 the shown planar region 10 and bent region 20 are formed. The surfaces of the anode electrode sheet, the separator, and the cathode electrode sheet in the planar region are not bent into a plane, and the surfaces in the bent region are bent into bent surfaces. The first position can cover at least a part of the bent surface, for example, cover the entire curved surface of the bent surface, or cover the central region of the bent surface, or cover any other suitable region of the bent surface.

[0061] 105: The electrode assembly is encapsulated in a housing.

[0062] 106: The swelling material layer of the electrode assembly is subjected to a swelling treatment, and the electrode assembly is subjected to a pressing treatment. The pressing direction of the pressing treatment is perpendicular to the plane.

[0063] When the swelling material layer uses a liquid-absorbing swelling adhesive tape, the swelling treatment is to inject electrolyte into the housing. After the liquid-absorbing swelling adhesive tape absorbs liquid and bulges, a pressure is applied to the housing in a direction perpendicular to the plane, so that the bulging stress is released to the side, thereby achieving the purpose of reducing the gap between the electrode sheets. Among them, the housing can be pressed by a fixture to apply pressure to the housing.

[0064] That is, first, the anode electrode sheet and the cathode electrode sheet are subjected to the first coating, the first position is estimated, one or more first positions are selected to paste the liquid-absorbing swelling adhesive tape, then stacked and wound to form an electrode assembly, and then the electrode assembly is placed in the housing, electrolyte is injected, and pressure is applied to the housing.

[0065] In some other embodiments, the swelling material layer can use a heat-expandable adhesive tape. The heat-expandable adhesive tape contains a heat-expandable material. After the heat-expandable material is heated, it expands and generates stress, thereby squeezing the electrode sheets in the bent region and reducing the gap between the electrode sheets.

[0066] For the pasting position of the heat-expandable adhesive tape, please refer to the liquid-absorbing expandable adhesive tape, which will not be elaborated here. The difference between the two is that the heat-expandable material is used instead of the liquid-absorbing expandable material.

[0067] In one of the embodiments, as Figure 5 shown, the heat-expandable adhesive tape includes a second substrate 214 and a second glue layer 213 provided on the second substrate 214. The heat-expandable material can be added to the second substrate 214 or the second glue layer 213. Of course, the heat-expandable material can also be added to both the second substrate 214 and the second glue layer 213.

[0068] Specifically, in some of the embodiments, the heat-expandable material can be a polymer material with a coefficient of thermal expansion greater than (1*10E-4) m / mK. For example, at least one of polycaprolactam, ethylene-ethyl acrylate, and cellulose acetate.

[0069] The above polymer materials are stable in an acidic or alkaline environment, will not undergo side reactions with the electrolyte, have a stable structure, exist stably within the battery operating voltage range, and their volume can change significantly after heating. After heating, the polymer expands in volume, achieving the effect of extruding and bending the pole pieces within the bending area and reducing the gap between the pole pieces. When the temperature decreases, the shape of the heat-expandable adhesive tape is fixed, which can maintain the gap in the bending area without repeating, and at the same time, the rigid stress after shaping can reduce the risk of battery deformation.

[0070] In one of the embodiments, if the heat-expandable material is added to the second substrate 214, the weight ratio of the heat-expandable material in the second substrate 214 is preferably maintained at 1 / 10 to 1 / 2; if the heat-expandable material is added to the second glue layer, the weight ratio of the heat-expandable material in the second glue layer is preferably maintained at 1 / 10 to 1 / 5.

[0071] The above electrode assembly including the heat-expandable adhesive tape can also be obtained through Figure 4 the preparation method shown below. Taking one of the embodiments as an example for specific description. First, perform a primary coating on the anode pole piece and the cathode pole piece, estimate the first position, select one or more first positions to paste the heat-expandable adhesive tape, then stack and wind to form an electrode assembly, and then place the electrode assembly into the housing and inject the electrolyte. Heat the housing and apply pressure to the housing. When heated, the heat-expandable material in the heat-expandable adhesive tape expands due to heat, and the pressure applied to the housing causes the expansion stress to be released to the side of the electrode assembly, achieving the effect of reducing the gap in the bending area. Among them, the heat-expandable adhesive tape can be obtained by adding the heat-expandable material to the substrate and / or the glue layer of the existing adhesive tape.

[0072] In some other embodiments, the expansion material layer can use an electrified expansion material layer, which contains an electrified expansion material. When the electrified expansion material is electrified, it expands, generates stress, thereby extruding the electrode tab in the bending area, and can reduce the gap between the electrode tabs.

[0073] In some of these embodiments, the electrified expansion material can be provided only on the first electrode tab in the bending area, that is, as Figure 6 shown, only a discontinuous first electrified expansion material layer 21 is provided on the first electrode tab a. The discontinuous first electrified expansion material layer can be formed by intermittently coating the electrified expansion material on the first electrode tab a. In this embodiment, the first electrified expansion material layer can cover at least a part of the bent surface of the first surface of the first electrode tab, for example, cover the entire curved surface of the bent surface, or cover the central area of the bent surface.

[0074] In some other embodiments, for the convenience of preparation, as Figure 7 shown, a continuous electrified expansion material layer can also be provided on the first electrode tab a, that is, a first electrified expansion material layer is provided on the first electrode tab in the bending area, and a second electrified expansion material layer is provided on the first electrode tab in the planar area layer. The first electrified expansion material layer and the second electrified expansion material layer are an integral structure and include the same electrified expansion material. The first electrified expansion material layer and the second electrified expansion material layer form a complete expansion material layer 21. The continuously provided electrified expansion material layer can be formed by continuously coating the electrified expansion material on the first electrode tab.

[0075] Among them, the first electrified expansion material layer or the second electrified expansion material layer can be provided on one or both sides of the first electrode tab. When provided on one side, it can be provided on the first surface of the first electrode tab, and the first surface is the surface of the first electrode tab away from the center of the electrode assembly. The electrified expansion material provided on the first surface can form an outward molecular force when electrified, which has a better extrusion effect compared to forming an inward molecular force on the other surface.

[0076] Specifically, in some of these embodiments, the electrified expansion material contains a Si-based or Sn-based material. The expansion rate of the Si-based or Sn-based material is much larger than that of the graphite material. Selecting a Si-based or Sn-based material with a large expansion rate but poor cycle performance is more conducive to the shaping of the battery after the first charge. Among them, the Si-based or Sn-based material can be a single substance of Si and Sn or their alloy.

[0077] In some of these embodiments, the Si-based or Sn-based material is a material with a first efficiency lower than 70%. The first efficiency is the ratio of the reversible charge and discharge amount after charging to the total charging amount. The first efficiency of the material can be achieved by doping or coating the crystal structure during the material synthesis process. The lower the first efficiency, the more conducive to shaping. Selecting a material with a lower first efficiency is more conducive to the shaping of the battery after charging.

[0078] In one embodiment, the thicknesses of the first electro-thermal expansion material layer and the second electro-thermal expansion layer are less than 10% of the diaphragm thickness of the first electrode tab, and the thickness range is 1 - 20 μm.

[0079] The above-mentioned electrode assembly containing electro-thermal expansion material can be obtained by Figure 4 the preparation method shown below. Taking one embodiment as an example for specific illustration. First, perform a primary coating on the anode tab and the cathode tab. When the electro-thermal expansion material is only arranged in the bending area, first estimate the first position on the first surface of the first electrode tab, and select one or more first positions to intermittently perform a secondary coating of the electro-thermal expansion material. When the electro-thermal expansion material is arranged in both the bending area and the flat area, directly perform a secondary coating of the electro-thermal expansion material on the first surface of the first electrode tab after the primary coating. Then laminate and wind to form an electrode assembly, and then place the electrode assembly into a housing and inject an electrolyte. Charge the electrode assembly, and apply pressure to the housing during the charging process. When charging, the electro-thermal expansion material expands due to heat, and the pressure applied to the housing causes the expansion stress to be released to the side of the electrode assembly, achieving the effect of reducing the gap in the bending area. After charging activation and shaping are completed, perform a degassing treatment to obtain the electrode assembly.

[0080] Among them, since the activity of the material in the secondary coating is lower than that of the material in the primary coating, the contents of the conductive agent and the binder in the material of the secondary coating need to be higher than those of the material in the primary coating. For example, the ratio of the slurry, conductive agent, and binder in the secondary coating is 90:5:5, and the ratio of the slurry, conductive agent, and binder in the primary coating is 98:1:1.

[0081] The embodiment of the present application also provides a battery, as Figure 8 shown, the battery includes a housing 200 and an electrode assembly 100. Among them, the electrode assembly 100 can adopt the electrode assembly in any of the above embodiments to improve the consistency of the battery interface. For the specific structure, composition, and effects of the electrode assembly in the embodiment of the present application, please refer to the above embodiments and will not be elaborated here.

[0082] The embodiment of the present application also provides an electronic device including the above-mentioned battery. Since the above-mentioned battery is adopted in this electronic device, the battery has a longer service life and better battery stability. The electronic device in the embodiment of the present application exists in various forms, including but not limited to:

[0083] (1) Mobile communication devices: Such devices are characterized by having mobile communication functions and mainly aim to provide voice and data communication. Such terminals include: smart phones (such as iPhone), multimedia phones, functional phones, and low-end phones, etc.

[0084] (2) Ultra-mobile personal computer devices: These devices fall within the category of personal computers, have computing and processing capabilities, and generally also have the feature of mobile Internet access. Such terminals include: PDA, MID, and UMPC devices, etc., such as the iPad.

[0085] (3) Portable entertainment devices: These devices can display and play multimedia content. Such devices include: audio and video players (such as the iPod), handheld game consoles, e-books, and smart toys and portable in-vehicle navigation devices.

[0086] (4) Servers: Devices that provide computing services. The composition of a server includes a processor, hard disk, memory, system bus, etc. Servers are similar to general computer architectures, but due to the need to provide highly reliable services, they have higher requirements in terms of processing power, stability, reliability, security, scalability, manageability, etc.

[0087] (5) Other devices that may use batteries.

[0088] The above are only the embodiments of the present application, and do not limit the patent scope of the present application. Any equivalent structural or equivalent process transformations made by using the content of the specification and drawings of the present application, or directly or indirectly applied in other related technical fields, are equally included in the patent protection scope of the present application.

[0089] Finally, it should be noted that: The above embodiments are only used to illustrate the technical solutions of the present application, rather than limiting them; under the idea of the present application, the technical features in the above embodiments or different embodiments can also be combined, and the steps can be implemented in any order, and there are many other variations in different aspects of the present application as described above. For the sake of brevity, they are not provided in detail; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An electrode assembly, which is formed by winding a first pole piece, a second pole piece and a separator, wherein, The separator is disposed between the first electrode and the second electrode; The electrode assembly includes a planar region and bent regions on both sides of the planar region. An expansion material layer is disposed between layers of the bent regions, and the expansion material layer contains an expandable material; Wherein, the expansion material layer is a liquid-absorbing and expanding adhesive tape; or, the expansion material layer is a heat-expanding adhesive tape; or, the expansion material layer is a first electrically conductive expanding material layer, and the first electrically conductive expanding material layer is coated on a first surface of the first electrode, and the first electrically conductive expanding material layer contains an electrically conductive expanding material.

2. The electrode assembly according to claim 1, wherein The liquid-absorbing and expanding adhesive tape includes a first substrate and a first glue layer disposed on the first substrate, and the first substrate and / or the first glue layer contains a liquid-absorbing and expanding material.

3. The electrode assembly according to claim 2, characterized in that, The liquid-absorbing and expanding material includes at least one of polycaprolactam, sodium polyacrylate, and lithium polyacrylate.

4. The electrode assembly according to claim 2 or 3, characterized in that If the first substrate includes the liquid-absorbing and expanding material, the weight ratio of the liquid-absorbing and expanding material in the first substrate is 1 / 10 to 1 / 2; If the first glue layer includes the liquid-absorbing and expanding material, the weight ratio of the liquid-absorbing and expanding material in the first glue layer is 1 / 10 to 1 / 5.

5. The electrode assembly according to claim 1, wherein The heat-expanding adhesive tape includes a second substrate and a second glue layer disposed on the second substrate, and the second substrate and / or the second glue layer contains a heat-expanding material.

6. The electrode assembly according to claim 5, characterized in that, The heat-expanding material is a polymer material with a coefficient of thermal expansion greater than (1*10E-4) m / mK.

7. The electrode assembly according to claim 6, wherein The polymer material includes at least one of polycaprolactam, ethylene-ethyl acrylate, and cellulose acetate.

8. The electrode assembly according to any one of claims 5-7, characterized in that, If the second substrate includes the heat-expanding material, the weight ratio of the heat-expanding material in the second substrate is 1 / 10 to 1 / 2; If the second glue layer includes the heat-expanding material, the weight ratio of the heat-expanding material in the second glue layer is 1 / 10 to 1 / 5.

9. The electrode assembly according to claim 1, characterized in that, A second electrically conductive expanding material layer is disposed between layers of the planar region, and the second electrically conductive expanding material layer is coated on the first surface of the first electrode. The first electrically conductive expanding material layer and the second electrically conductive expanding material layer are an integral structure and include the same electrically conductive expanding material.

10. The electrode assembly according to claim 1 or 9, characterized in that, The first surface is the surface of the first electrode away from the center of the electrode assembly.

11. The electrode assembly according to any one of claims 1, 9 - 10, characterized in that, The electrically conductive expanding material contains a Si-based material or a Sn-based material.

12. The electrode assembly according to claim 11, wherein, The Si-based material or the Sn-based material is a material with a first efficiency lower than 70%.

13. The electrode assembly according to any one of claims 1, 9 - 10, characterized in that, The thickness of the first electrically conductive expanding material layer is less than 10% of the film thickness of the first electrode.

14. A battery, comprising: A housing; The electrode assembly according to any one of claims 1-13, and the electrode assembly is disposed in the housing.

15. An electronic device, comprising: The battery according to claim 14.

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