Battery monomer, battery device and electric equipment

Abstract

The invention relates to the technical field of batteries, and discloses a battery monomer, a battery device and electric equipment.The battery monomer comprises a shell and an electrode assembly, the shell is provided with a first wall and a circumferential side wall connected with the first wall, and the first wall is provided with a pressure relief mechanism; the electrode assembly is arranged in the shell, the first wall is located at one end of the electrode assembly, and the circumferential side wall surrounds the outer side of the electrode assembly; a thermal expansion part is arranged on the electrode assembly, a thermal expansion part is arranged on the inner wall surface of the circumferential side wall and / or in the wall body of the circumferential side wall and / or between the circumferential side wall and the electrode assembly, and the thermal expansion part is set to expand under the condition that the temperature is greater than or equal to a preset temperature, so that the electrode assembly and the circumferential side wall are pressed and matched with each other. The possibility that the electrode assembly blocks the pressure relief cavity channel between the first side wall and the electrode assembly and the pressure relief mechanism is reduced, the timeliness of discharging gas and other emissions generated in the battery monomer from the pressure relief mechanism is improved, and the thermal runaway risk of the battery monomer is reduced.

Description

Technical Field

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

[0002] This section merely provides background information related to the present application and is not necessarily prior art.

[0003] A battery device may include one or more battery cells. When a battery device is subjected to external short circuit, overcharge, needle puncture, plate impact, etc., thermal runaway may occur easily. When the degree of thermal runaway is serious, there may even be a risk of explosion. How to reduce the hazards caused by thermal runaway of battery devices is an issue that cannot be ignored in the process of battery technology development. Summary of the invention

[0004] In view of the above problems, the present application provides a battery cell, a battery device and an electrical device to reduce the possibility of causing greater harm to the battery device during thermal runaway.

[0005] The first aspect of the present application provides a battery cell, comprising a shell and an electrode assembly, wherein the shell has a first wall and a circumferential side wall connected to the first wall, and the first wall is provided with a pressure relief mechanism; the electrode assembly is arranged in the shell, wherein the first wall is located at one end of the electrode assembly, and the circumferential side wall surrounds the outside of the electrode assembly, and the electrode assembly comprises a positive electrode, a negative electrode and a separator, wherein the separator is arranged between the negative electrode and the positive electrode, and the separator is used to electrically insulate the adjacent positive electrode and the negative electrode, and to transmit ions between the adjacent positive electrode and the negative electrode, and the positive electrode A thermal expansion portion is provided on the positive electrode, and / or a thermal expansion portion is provided on the negative electrode, and / or a thermal expansion portion is provided on the isolation member, and / or a thermal expansion portion is provided between the positive electrode and the isolation member, and / or a thermal expansion portion is provided between the negative electrode and the isolation member; and a thermal expansion portion is provided on the inner wall surface of the circumferential side wall, and / or a thermal expansion portion is provided in the wall body of the circumferential side wall, and / or a thermal expansion portion is provided between the circumferential side wall and the electrode assembly; the thermal expansion portion is configured to expand when the temperature is greater than or equal to a preset temperature, so that the electrode assembly and the circumferential side wall are pressed against each other.

[0006] In the technical solution of the embodiment of the present application, the temperature at which thermal runaway occurs in the battery cell is usually higher than the preset temperature. When thermal runaway occurs in the battery cell, the temperature of the environment in which the thermal expansion part is located increases, causing the thermal expansion part to swell, and the electrode assembly and the circumferential side walls of the outer shell are pressed against each other. Under the restraining effect of the circumferential side walls, the possibility of the electrode assembly moving toward the first wall is reduced, thereby reducing the possibility of the electrode assembly blocking the pressure relief cavity and the pressure relief mechanism between the first side wall and the electrode assembly, improving the timeliness of the discharge of emissions such as gas generated inside the battery cell from the pressure relief mechanism, reducing the possibility of greater harm to the battery cell due to the accumulation of emissions, and reducing the risk of thermal runaway of the battery cell.

[0007] In addition, the battery cell according to the present application may also have the following additional technical features: In some embodiments of the present application, a discharge channel is provided between the circumferential side wall and the electrode assembly, and the thermal expansion portion is provided to avoid at least a portion of the discharge channel. In the battery cell of this embodiment, the thermal expansion portion is provided to avoid at least a portion of the discharge channel. When thermal runaway occurs in the battery, the emission can flow to the pressure relief mechanism through the emission channel avoided by the thermal expansion portion, which reduces the movement of the electrode assembly and provides the timeliness of emission discharge, reduces the possibility of greater harm to the battery cell due to the accumulation of emission, and reduces the risk of thermal runaway of the battery cell.

[0008] In some embodiments of the present application, the discharge channel includes a first discharge channel, and the first discharge channel is provided on one side of the electrode assembly along the first direction. When the thermal expansion part is expanded, the electrode assembly and the circumferential side wall are pressed against each other along the second direction, and the first direction intersects with the second direction, and the first direction and the second direction both intersect with the arrangement direction of the first wall and the electrode assembly. The direction in which the circumferential side wall and the electrode assembly are pressed against each other (i.e., the second direction) intersects with the first direction, so that in the case of thermal runaway of the battery cell, the first discharge channel provided on the first direction side of the electrode assembly can remain connected, which provides timeliness of emission of emissions while reducing the movement of the electrode assembly, reduces the possibility of greater harm to the battery cell due to the accumulation of emissions, and reduces the risk of thermal runaway of the battery cell.

[0009] In some embodiments of the present application, the electrode assembly includes a straight portion and a curved portion, the circumferential side wall includes a first side wall arranged opposite to the straight portion and a second side wall arranged opposite to the curved portion, the first discharge channel is arranged between the curved portion and the second side wall, the thermal expansion portion is arranged on the first side wall, and / or the thermal expansion portion is arranged between the first side wall and the straight portion, and / or the thermal expansion portion is arranged on the straight portion. When the temperature is greater than or equal to a preset temperature, the expansion of the thermal expansion portion can make the first wall and the straight portion press against each other to restrain the movement of the electrode assembly toward the first wall. Since the straight portion and the first wall corresponding to the area where the thermal expansion portion is located are roughly flat, the probability of the electrode assembly and the circumferential side wall being tightly pressed against each other after the thermal expansion portion is expanded can be increased, and the thermal expansion portion is designed to be more expandable and controllable.

[0010] In some embodiments of the present application, the electrode assembly includes a first side surface and a second side surface, the area of ​​the first side surface is larger than that of the second side surface, the circumferential side wall includes a first side wall and a second side wall, the first side wall and the first side surface are arranged opposite to each other, the second side wall and the second side surface are arranged opposite to each other, the first discharge channel is arranged between the second side wall and the second side wall, the first side wall is provided with the thermal expansion part, and / or the thermal expansion part is provided between the first side wall and the first side surface, and / or the thermal expansion part is provided on the first side surface, and / or the thermal expansion part is provided in the electrode assembly. The thermal expansion part can avoid the first discharge channel between the second side surface and the second side wall, and when the temperature is greater than or equal to the preset temperature, the expansion of the thermal expansion part can make the first wall and the first side surface with a larger area press against each other to restrain the movement of the electrode assembly to the first wall. Since the area of ​​the first side surface and the first wall corresponding to the area where the thermal expansion part is located is larger, the probability of the electrode assembly and the circumferential side wall being tightly pressed against each other after the thermal expansion part is expanded can be increased, and the thermal expansion part is designed to be more expandable and controllable.

[0011] In some embodiments of the present application, the battery cell further comprises an insulating film, the insulating film is coated on the outside of the electrode assembly and is located in the shell, at least a portion of the insulating film between the electrode assembly and the circumferential side wall is provided as the thermal expansion portion and / or the surface of at least a portion of the insulating film between the electrode assembly and the circumferential side wall is provided with the thermal expansion portion. In the case of thermal runaway of the battery cell, the temperature of the environment where the thermal expansion portion on the insulating film is located increases, causing the thermal expansion portion to expand, and the electrode assembly, the insulating film and the circumferential side wall of the shell are pressed against each other. Under the restraining effect of the circumferential side wall, the possibility of the electrode assembly moving toward the first wall is reduced, thereby reducing the possibility of the electrode assembly blocking the pressure relief cavity and the pressure relief mechanism between the first side wall and the electrode assembly, improving the timeliness of the discharge of the gas and other emissions generated inside the battery cell from the pressure relief mechanism, reducing the possibility of greater harm to the battery cell due to the accumulation of emissions, and reducing the risk of thermal runaway of the battery cell.

[0012] In some embodiments of the present application, at least a portion of the insulating film between the electrode assembly and the circumferential side wall is configured as a composite film structure having a thermal expansion substance, and the portion of the insulating film configured as the composite film structure forms the thermal expansion portion. By configuring at least a portion of the insulating film as a composite film structure having a thermal expansion substance, in the event of thermal runaway of the battery cell, the temperature of the environment where the thermal expansion portion is located increases, causing the thermal expansion portion to expand, and the electrode assembly, the insulating film, and the circumferential side wall of the housing are pressed against each other, and under the restraining effect of the circumferential side wall, the possibility of the electrode assembly moving toward the first wall is reduced.

[0013] In some embodiments of the present application, a containing cavity is provided in at least a portion of the film body of the insulating film between the electrode assembly and the circumferential side wall, the heat expansion material is provided in the containing cavity to form the heat expansion part, and the position of the insulating film corresponding to the heat expansion part is set to be able to extend, expand or rupture under the action of the expansion of the heat expansion part. By filling the heat expansion part in the film body of the insulating film to form a composite film structure, in the case of thermal runaway of the battery cell, the temperature of the environment where the heat expansion part is located increases, causing the heat expansion part to expand, and the electrode assembly, the insulating film and the circumferential side wall of the shell are pressed against each other, and under the restraining action of the circumferential side wall, the possibility of the electrode assembly moving toward the first wall is reduced.

[0014] In some embodiments of the present application, at least a portion of at least one of the positive electrode, the negative electrode, and the separator is a composite structure having a thermal expansion material, and the composite structure forms the thermal expansion portion. By having at least one of the positive electrode, the negative electrode, and the separator be a composite structure having a thermal expansion material, when a battery cell undergoes thermal runaway, the temperature of the environment where the thermal expansion portion is located increases, causing the thermal expansion portion of the composite structure to expand, and the electrode assembly, the insulating film, and the circumferential side walls of the housing are pressed against each other, and under the restraining effect of the circumferential side walls, the possibility of the electrode assembly moving toward the first wall is reduced.

[0015] In some embodiments of the present application, at least one of the surface of the positive electrode, the surface of the negative electrode, and the surface of the separator is provided with the thermal expansion portion. By providing the thermal expansion portion on the surface of the positive electrode, the surface of the negative electrode, and / or the surface of the separator, these expansion portions can not only expand when the temperature is greater than or equal to the preset temperature to reduce the possibility of movement of the battery cell, but also reduce the short-circuit sites between the positive electrode and the negative electrode due to their expansion performance, thereby reducing the probability of failure.

[0016] In some embodiments of the present application, the battery cell further includes an insulating film, which is coated on the outside of the electrode assembly and is located inside the shell; the thermal expansion portion is formed on the circumferential side wall by coating, and / or the thermal expansion portion is formed on the insulating film by coating, and / or the thermal expansion portion is formed on the electrode assembly by coating. In this embodiment, the thermal expansion portion is formed by coating, which is convenient to process and is not likely to affect the performance of the carrier (circumferential side wall, insulating film, outer surface of the electrode assembly, positive electrode, negative electrode or separator).

[0017] In some embodiments of the present application, the material of the thermal expansion part includes an adhesive and a thermal expansion substance.

[0018] In some embodiments of the present application, the heat expansion portion includes a flexible sleeve and a heat expansion substance, and the flexible sleeve is coated on the outside of the heat expansion substance.

[0019] In some embodiments of the present application, the heat expansion portion includes a heat expansion material, and the heat expansion material includes calcium gluconate; and / or the preset temperature ranges from 80°C to 130°C.

[0020] In some embodiments of the present application, the preset temperature is 80°C.

[0021] In some embodiments of the present application, the battery cell further includes an insulating film, which is coated on the outside of the electrode assembly and is located in the shell; when the thermal expansion part is expanded, the electrode assembly and the circumferential side wall are pressed against each other along the second direction, and when the temperature is less than the preset temperature, the sum of the gap size between the electrode assembly and the insulating film and the gap size between the insulating film and the circumferential side wall along the second direction is H, and when the temperature is greater than or equal to the preset temperature, the total expansion size of the electrode assembly, the insulating film and the thermal expansion part along the second direction is greater than H, and the second direction intersects with the arrangement direction of the first wall and the electrode assembly. In the case of thermal runaway of the battery cell, the restraining effect of the circumferential side wall on the electrode assembly is improved, and the possibility of the electrode assembly moving toward the first wall is reduced.

[0022] A second aspect of the present application provides a battery device, comprising a plurality of battery cells provided in the present application or any embodiment of the present application.

[0023] The battery device of this embodiment has the same beneficial effects as the battery cell proposed in this application or any embodiment of this application.

[0024] The third aspect of the present application proposes an electrical device, which includes a battery cell proposed in the present application or any embodiment of the present application, or the electrical device includes a battery device proposed in the present application or any embodiment of the present application, and the battery cell is used to store or provide electrical energy.

[0025] The electrical equipment of this embodiment has the same beneficial effects as the battery cell proposed in this application or any embodiment of this application.

[0026] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Moreover, the same reference numerals are used throughout the accompanying drawings to represent the same components. In the accompanying drawings: Figure 1 A schematic diagram of the structure of a vehicle provided in some embodiments of the present application; Figure 2 A schematic diagram of a battery device according to some embodiments of the present application; Figure 3A schematic diagram of a battery cell according to some embodiments of the present application; Figure 4 A schematic cross-sectional view of an electrode assembly according to some embodiments of the present application; Figure 5 A schematic cross-sectional view of an electrode assembly according to some embodiments of the present application; Figure 6 A schematic cross-sectional view of a battery cell according to some embodiments of the present application; Figure 7 for Figure 6 A magnified view of part A; Figure 8 A schematic cross-sectional view of a battery cell according to some embodiments of the present application; Fig. 9 for Figure 8 A magnified view of part B; Fig.10 A schematic cross-sectional view of a battery cell according to some embodiments of the present application; Fig.11 A schematic cross-sectional view of a battery cell according to some embodiments of the present application; Fig.12 A schematic cross-sectional view of a battery cell according to some embodiments of the present application Fig.13 A schematic cross-sectional diagram of an electrode assembly according to some embodiments of the present application; Fig.14 A schematic cross-sectional diagram of an electrode assembly according to some embodiments of the present application; Fig.15 A schematic cross-sectional diagram of an electrode assembly according to some embodiments of the present application; Fig.16 Schematic diagram of the thermal expansion portion of some embodiments of the present application.

[0028] The reference numerals in the specific implementation manner are as follows: 1000, vehicle; 10, battery device; 11, first box; 12, second box; 13, box; 20, controller; 30, motor; 100, battery cell; 110, shell; 111, shell; 1111, circumferential side wall; 1112, first side wall; 1113, second side wall; 112, end cover; 113, first wall; 114, electrode terminal; 115, pressure relief mechanism; 120, electrode assembly; 1201, first side surface; 1202, second side surface; 1203, straight portion; 1204, curved portion; 121, positive electrode; 122, negative electrode; 123, separator; 124, separator; 125, pole ear; 126, current collecting member; 130, insulating protection member; 140, insulating film; 150, thermal expansion portion; 151, thermal expansion material; 152, flexible sleeve; 160, discharge channel; 161, first discharge channel; 162, second discharge channel; X, first direction; Y, second direction; Z, arrangement direction. DETAILED DESCRIPTION

[0029] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0031] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0032] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0033] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0034] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0035] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0036] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0037] With the vigorous development of the new energy industry, the capacity of battery devices is getting larger and larger, and the performance requirements for battery devices are also getting higher and higher. Battery devices usually include one or more battery cells. When the battery cells are in external short circuit, overcharge, needle puncture, plate impact, etc., thermal runaway is easy to occur. A pressure relief mechanism can be set on the outer shell of the battery cell to discharge high-temperature smoke, high-temperature particulate matter and other emissions in time when the battery cell has thermal runaway.

[0038] An insulating protective member is usually provided between the wall of the battery cell housing with a pressure relief mechanism and the electrode assembly. The insulating protective member can support and fix the electrode assembly in the housing so that the electrode assembly can be stably arranged in the housing, and can also isolate the housing from the electrical connection components in the housing to reduce the possibility of short circuit in the battery cell. The insulating protective member is provided with an opening corresponding to the pressure relief mechanism. When the battery cell is in thermal runaway, the opening allows the discharge to reach the pressure relief mechanism smoothly, thereby allowing the pressure relief mechanism to actuate the pressure relief, reducing the extreme situation of battery cell explosion.

[0039] Research has found that when a battery cell experiences thermal runaway, emissions still cannot be discharged in time, leading to more serious hazards such as fire and explosion of the battery cell. Based on the occurrence of this situation, further research has found that during thermal runaway of the battery cell, high temperature environment or high temperature emissions will cause the insulating protective parts to melt, and the insulating protective parts will fail to support the electrode assembly. The electrode assembly may move toward the pressure relief mechanism under the impact of gas and other emissions, blocking the pressure relief cavity or pressure relief mechanism between the electrode assembly and the shell, resulting in the inability to discharge emissions in time and the inability of the battery cell to release pressure in time.

[0040] Based on the above research, in order to alleviate the possibility of causing greater harm during thermal runaway of a battery cell, the present application provides a battery cell having a thermal expansion portion disposed therein. The thermal expansion portion can be configured to expand at a temperature greater than or equal to a preset temperature, so that the electrode assembly and the circumferential side wall are pressed against each other.

[0041] The preset temperature can be set to be lower than the temperature at which the battery undergoes thermal runaway. In the event of thermal runaway of the battery cell, the temperature of the environment where the thermal expansion portion is located increases, causing the thermal expansion portion to expand, and the electrode assembly and the circumferential side wall of the housing are pressed against each other. Under the restraining effect of the circumferential side wall, the possibility of the electrode assembly moving toward the first wall is reduced, reducing the possibility of the electrode assembly moving and blocking the pressure relief mechanism on the first side wall and the pressure relief cavity between the wall where the pressure relief mechanism is located and the electrode assembly, improving the timeliness of the discharge of emissions such as gas generated inside the battery cell from the pressure relief mechanism, reducing the possibility of greater harm to the battery cell due to the accumulation of emissions, and reducing the risk of thermal runaway of the battery cell.

[0042] The battery cells disclosed in the embodiments of the application can be used in electrical equipment, and a power supply system having the battery cells, battery devices, etc. disclosed in the application to form the electrical equipment can be used.

[0043] The embodiment of the present application provides an electric device using a battery device as a power source, and the electric device may be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, a battery car, an electric car, a ship, a spacecraft, etc. Among them, the electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc., and the spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0044] It should be understood that the battery cells or battery devices described in the embodiments of the present application are not limited to the above-described electrical equipment, but can also be applied to all equipment using battery devices. However, for the sake of simplicity, the following embodiments are described using electric vehicles as examples.

[0045] Please refer to Figure 1 , Figure 1 A schematic diagram of the structure of a vehicle provided for some embodiments of the present application. The vehicle 1000 may be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery device 10 is provided inside the vehicle 1000, and the battery device 10 may be provided at the bottom, head or tail of the vehicle 1000. The battery device 10 may be used to power the vehicle 1000, for example, the battery device 10 may be used as an operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 20 and a motor 30, and the controller 20 is used to control the battery device 10 to power the motor 30, for example, for starting, navigating and driving the vehicle 1000.

[0046] In some embodiments of the present application, the battery device 10 can not only serve as an operating power source for the vehicle 1000, but also serve as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0047] The battery apparatus 10 (Battery Apparatus) mentioned in the embodiment of the present application may include one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly (Battery Cell Assembly) may include a plurality of battery cells 100, and the plurality of battery cells 100 are connected in series, in parallel or in mixed connection through a busbar component.

[0048] In some embodiments, a battery cell assembly is generally formed by arranging a plurality of battery cells 100 .

[0049] As an example, the battery cell assembly may be a battery module (Battery Module), and the battery module is formed by arranging and fixing a plurality of battery cells 100 to form an independent module. As an example, the battery module may be formed by bundling a plurality of battery cells 100 by a cable tie.

[0050] In some embodiments, Figure 2 As shown, Figure 2 This is a schematic diagram of a battery device according to some embodiments of the present application. The battery device 10 may be a battery pack, which includes a box 13 and one or more battery cell assemblies, wherein the battery cell assemblies are accommodated in the box 13 .

[0051] As an example, the battery cell assembly may be a battery module, and the battery cell assembly may be accommodated in the box body 13 by fixing the battery module in the box body 13 .

[0052] As an example, the battery cell assembly may also be accommodated in the case 13 by directly fixing the plurality of battery cells 100 to the case 13 .

[0053] As an example, Figure 2 As shown, the box 13 may include a first box 11 and a second box 12. The first box 11 and the second box 12 are buckled together to form a closed space inside the box 13 to accommodate the battery monomer assembly. The closed here means covered or closed, which can be sealed or unsealed. The first box 11 can be a top cover or a bottom plate.

[0054] As an example, the box body 13 may include a top cover, a frame and a bottom plate. The top cover and the bottom plate are respectively connected to the frame, so that a closed space is formed inside the box body 13 to accommodate the battery monomer assembly.

[0055] In some embodiments, the box 13 may be a part of the chassis structure of the vehicle 1000. For example, part of the box 13 may become at least a part of the floor of the vehicle 1000, or part of the box 13 may become at least a part of the cross beam and longitudinal beam of the vehicle 1000.

[0056] In the embodiment of the present application, the battery cell 100 may be a secondary battery. A secondary battery refers to a battery cell 100 that can be continuously used by activating active materials by charging after the battery cell 100 is discharged.

[0057] The battery cell 100 can be a lithium ion battery, a sodium ion battery, a sodium lithium ion battery, a lithium metal battery, a sodium metal battery, a lithium sulfur battery, a magnesium ion battery, a nickel hydrogen battery, a nickel cadmium battery, a lead storage battery, etc., which is not limited in the embodiments of the present application.

[0058] like Figure 3 As shown, Figure 3 This is a schematic diagram of a battery cell according to some embodiments of the present application. The battery cell 100 may include a housing 110 and an electrode assembly 120 . The electrode assembly 120 is disposed in the housing 110 .

[0059] like Figure 4 and Figure 5 As shown, Figure 4 is a cross-sectional schematic diagram of an electrode assembly according to some embodiments of the present application. Figure 5 The cross-sectional schematic diagram of the electrode assembly of some embodiments of the present application, the electrode assembly 120 includes a positive electrode 121, a negative electrode 122 and a separator 123, and the separator 123 is arranged between the negative electrode 122 and the positive electrode 121. During the charge and discharge process of the battery cell 100, active ions (such as lithium ions) are embedded and removed back and forth between the positive electrode 121 and the negative electrode 122. The separator 123 is arranged between the positive electrode 121 and the negative electrode 122, which can prevent the positive and negative electrodes from short-circuiting, and at the same time allow the active ions to pass through.

[0060] In some embodiments, the positive electrode 121 may be a positive electrode sheet, which may include a positive electrode collector and a positive electrode active material disposed on at least one surface of the positive electrode collector.

[0061] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material is disposed on either or both of the two facing surfaces of the positive electrode current collector.

[0062] As an example, the positive electrode current collector may be a metal foil, a conductive polymer material, a carbon material or a composite current collector. For example, as the metal foil, a pure metal, an alloy, a surface-treated metal, including but not limited to stainless steel, copper, aluminum, nickel, titanium or silver, etc., may be used. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0063] As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more.

[0064] In some embodiments, the negative electrode 122 may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0065] As an example, the negative electrode current collector may be a metal foil, a conductive polymer material, a carbon material or a composite current collector. For example, as the metal foil, a pure metal, an alloy, a surface-treated metal, including but not limited to stainless steel, copper, aluminum, nickel, nickel, titanium or silver, etc., may be used. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0066] As an example, the negative electrode sheet may include a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector.

[0067] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material is disposed on either or both of the two facing surfaces of the negative electrode current collector.

[0068] As an example, the negative electrode active material may adopt the negative electrode active material known in the art for the battery cell 100. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc.

[0069] In some embodiments, the negative electrode 122 may be a foam metal. The foam metal may be foam nickel, foam copper, foam aluminum, foam alloy, foam carbon, etc. When the foam metal is used as the negative electrode sheet, the surface of the foam metal may not be provided with a negative electrode active material, but of course, a negative electrode active material may also be provided.

[0070] As an example, a negative electrode active material may be filled and / or deposited in the negative electrode current collector.

[0071] In some embodiments, the material of the positive electrode current collector may be aluminum, and the material of the negative electrode current collector may be copper.

[0072] In some embodiments, the isolation member 123 is an isolation membrane 124. The present application has no particular limitation on the type of the isolation membrane 124, and any known isolation membrane 124 with a porous structure having good chemical stability and mechanical stability can be selected.

[0073] As an example, the main material of the separator 124 can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramics. The separator 124 can be a single-layer film or a multi-layer composite film, without special restrictions. When the separator 124 is a multi-layer composite film, the materials of each layer can be the same or different, without special restrictions. The separator 123 can be a separate component located between the positive and negative electrodes 122, or it can be attached to the surface of the positive and negative electrodes 122. An inorganic particle coating, an organic particle coating, or an organic / inorganic composite coating can also be coated on the surface of the separator 124.

[0074] In some embodiments, the separator 123 is a solid electrolyte. The solid electrolyte is disposed between the positive electrode 121 and the negative electrode 122 and plays the role of transmitting ions and isolating the positive and negative electrodes 122 at the same time.

[0075] The electrode assembly 120 may be a wound structure, a laminated structure, or a mixed structure of a wound structure and a laminated structure.

[0076] In some embodiments, Figure 4 As shown, the electrode assembly 120 is a winding structure. The positive electrode sheet and the negative electrode sheet are wound into a winding structure.

[0077] In some embodiments, Figure 5 As shown, the electrode assembly 120 is a laminated structure. As an example, a plurality of positive electrode sheets and a plurality of negative electrode sheets can be provided respectively, and the plurality of positive electrode sheets and the plurality of negative electrode sheets can be alternately stacked.

[0078] In some embodiments, the shape of the electrode assembly 120 may be cylindrical, flat, or polygonal.

[0079] In some embodiments, the electrode assembly 120 is provided with tabs 125, which can conduct current from the electrode assembly 120. The tabs 125 include a positive tab and a negative tab.

[0080] The battery cell 100 also includes an electrolyte, which is disposed in the housing 110 and serves to conduct ions between the positive and negative electrodes 122. The present application has no specific restrictions on the type of electrolyte, which can be selected according to needs. The electrolyte can be liquid, gel or solid.

[0081] The housing 110 may be a steel housing, an aluminum housing, a plastic housing (such as polypropylene), a composite metal housing (such as a copper-aluminum composite housing 110), or an aluminum-plastic film. In some embodiments, the housing 110 may be a sealed structure or a non-sealed structure. As an example, when the housing 110 is a non-sealed structure, the housing 110 serves to protect the electrode assembly 120, and a sealed bag is further included between the housing 110 and the electrode assembly 120, and the sealed bag is used to encapsulate the electrode assembly 120 and the electrolyte. Specifically, the sealed bag may be a bag-shaped insulating member or an aluminum-plastic film. When the housing 110 is a sealed structure, it is used to encapsulate components such as the electrode assembly 120 and the electrolyte.

[0082] As an example, the battery cell 100 can be a cylindrical battery cell, a prismatic battery cell, a soft-pack battery cell or a battery cell of other shapes. The prismatic battery cell includes a square shell battery cell, a blade-shaped battery cell, a polygonal battery, such as a hexagonal battery, etc. There is no special limitation in the present application.

[0083] In some embodiments, the housing 110 includes an end cap 112 and a shell 111. The shell 111 is provided with an opening, and the end cap 112 is provided to cover the opening. The shell 111 may be provided with one or more openings. One or more end caps 112 may also be provided.

[0084] In some embodiments, at least one electrode terminal 114 is disposed on the housing 110, and the electrode terminal 114 is electrically connected to the electrode tab 125. The electrode terminal 114 may be directly connected to the electrode tab 125, or may be indirectly connected to the electrode tab 125 through the current collecting member 126. The electrode terminal 114 may be disposed on the end cap 112, or may be disposed on the housing 111.

[0085] In some embodiments, a pressure relief mechanism 115 is disposed on the housing 110 . The pressure relief mechanism 115 is used to discharge the internal gas of the battery cell 100 .

[0086] As an example, when the internal pressure or temperature of the battery cell 100 reaches a predetermined threshold, it is actuated to release the internal pressure or temperature. When the internal pressure or temperature of the battery cell 100 reaches a predetermined threshold, the pressure relief mechanism 115 performs an action or a weak structure provided in the pressure relief mechanism 115 is destroyed, thereby forming an opening or channel for the internal pressure or temperature to be released. The threshold design varies according to different design requirements. The threshold may depend on one or more materials of the positive electrode sheet, the negative electrode sheet, the electrolyte, and the separator 123 in the battery cell 100.

[0087] As an example, the pressure relief mechanism 115 may be integrally formed with the housing 110 .

[0088] As an example, the pressure relief mechanism 115 may also be separately provided and connected to the housing 110 .

[0089] As an example, the pressure relief mechanism 115 may be disposed on the end cover 112 .

[0090] The "actuation" mentioned in this application means that the pressure relief mechanism 115 is in action or activated to a certain state, so that the internal pressure and temperature of the battery cell 100 can be released. The action produced by the pressure relief mechanism 115 may include but is not limited to: the components in the pressure relief mechanism 115 move to form a discharge channel, at least a part of the pressure relief mechanism 115 ruptures, breaks, is torn or opened, and so on. When the pressure relief mechanism 115 is actuated, the high-temperature and high-pressure substances inside the battery cell 100 will be discharged from the actuated part as emissions. In this way, the battery cell 100 can be depressurized and cooled under controllable pressure or temperature, thereby avoiding potential more serious accidents.

[0091] In some embodiments, when the housing 110 is a non-sealed structure, the pressure relief mechanism 115 can be configured as a through hole to discharge the gas inside the battery cell 100 .

[0092] The emissions from the battery cells 100 mentioned in the present application include, but are not limited to: electrolyte, dissolved or split positive and negative electrode sheets, fragments of the separator 123, high-temperature and high-pressure gases generated by the reaction, flames, and the like.

[0093] The battery cell 100 may further include an insulating film 140, which may be coated on the outside of the electrode assembly 120 and located inside the housing 110, and may contact the inner wall surface of the housing 110. The insulating film 140 may be a MYLAR film, i.e., a polyester film, which is a film structure formed by a tough polyester polymer and has good insulation and heat resistance. The insulating film 140 may also serve as a protective layer for the electrode cell, effectively preventing leakage of substances inside the battery cell 100, and the insulating film 140 may serve as an isolation layer, effectively isolating the electrode assembly 120 from the housing 110, and reducing the short circuit phenomenon inside the battery cell 100.

[0094] The battery cell 100 may further include an insulating protective member 130, which may be located between the wall (e.g., the end cap 112) of the housing 110 provided with the pressure relief mechanism 115 and the electrode assembly 120. The insulating protective member 130 may be a plastic member, which may be prefabricated from plastic or assembled from various plastic parts, and the material is an insulating material. The insulating protective member 130 may also be a member of other materials, such as a rubber member. The insulating protection part 130 has two main functions. First, it can be used to isolate the electrical connection components in the outer shell 110 from the outer shell 110 (specifically the end cover 112) to reduce the risk of short circuit. Second, it can effectively support the end face of the electrode assembly 120. After the electrode assembly 120 is assembled into the shell and the end cover 112 is welded, the internal winding core of the electrode assembly 120 is in a state of slight pressure, and the electrode assembly 120 will also be in a vibrating environment during loading and use. If the electrode assembly 120 is not restrained enough, it will easily affect the life of the winding core or cause a short circuit. Therefore, the insulating protection part 130 needs to effectively support the end face of the winding core to reduce the possibility of the electrode assembly 120 moving up and down.

[0095] The insulating protection member 130 may be provided with openings corresponding to the pressure relief mechanism 115 , so that the discharge can flow to the pressure relief mechanism 115 through the openings.

[0096] A pressure relief cavity may be provided between the insulating protection member 130 and the electrode assembly 120 . When thermal runaway occurs in the battery cell 100 , the exhaust therein may flow from the pressure relief cavity to the pressure relief mechanism 115 .

[0097] A gap may be provided between the electrode assembly 120 and the housing 110 , and the gap may serve as a pressure relief passage. When thermal runaway occurs in the battery cell 100 , emissions away from the pressure relief mechanism 115 may flow from the pressure relief passage to the pressure relief mechanism 115 .

[0098] like Figure 3 As shown, combined with Figures 6 to 10 As shown, Figure 6 A schematic cross-sectional view of a battery cell according to some embodiments of the present application is shown in FIG. Figure 7 for Figure 6 A magnified view of part A. Figure 8 A schematic cross-sectional view of a battery cell according to some embodiments of the present application is shown in FIG. Fig. 9 for Figure 8 The enlarged view of part B, Fig.10The present invention provides a cross-sectional schematic diagram of a battery cell proposed in some embodiments of the present invention. The present embodiment provides a battery cell 100, including a housing 110 and an electrode assembly 120. The housing 110 has a first wall 113 and a circumferential side wall 1111 connected to the first wall 113. The first wall 113 is provided with a pressure relief mechanism 115. The electrode assembly 120 is disposed in the housing 110, wherein the first wall 113 is located at one end of the electrode assembly 120, and the circumferential side wall 1111 surrounds the electrode assembly. The outer side of 120; the inner wall surface of the circumferential side wall 1111 is provided with a thermal expansion portion 150, and / or the thermal expansion portion 150 is provided in the wall body of the circumferential side wall 1111, and / or the thermal expansion portion 150 is provided between the circumferential side wall 1111 and the electrode assembly 120, and / or the thermal expansion portion 150 is provided on the electrode assembly 120, and the thermal expansion portion 150 is configured to expand when the temperature is greater than or equal to a preset temperature, so that the electrode assembly 120 and the circumferential side wall 1111 are pressed against each other.

[0099] The first wall 113 is one of the walls of the housing 110 . The circumferential side wall 1111 is a wall circumferentially arranged around the first wall 113 . One end of the circumferential side wall 1111 (one axial end of the circumferential side wall 1111 itself) is connected to the first wall 113 .

[0100] Exemplarily, the first wall 113 may be the end cover 112 of the housing 110 , and the circumferential side wall 1111 is disposed between the end cover 112 and the bottom wall of the housing 110 .

[0101] Exemplarily, the first wall 113 may also be the bottom wall of the shell 111 , and the circumferential side wall 1111 is disposed between the end cover 112 of the housing 110 and the bottom wall.

[0102] Exemplarily, the first wall 113 may also be one of the side walls of the housing 110 , and the two side walls connected to the side wall, the end cover 112 , and the bottom wall are sequentially connected end to end to form a circumferential side wall 1111 .

[0103] The thermal expansion part 150 may be made of a material including a thermal expansion substance 151, and the thermal expansion part 150 is configured to expand when the temperature is greater than or equal to a preset temperature, which means that the thermal expansion part 150 can expand rapidly when the temperature is equal to the preset temperature, and can also increase rapidly when the temperature is greater than the preset temperature. The thermal expansion substance 151 may be insoluble in the electrolyte, and the volume of the thermal expansion substance 151 expands rapidly after being heated (when the preset temperature is reached or exceeds the preset temperature). When the battery cell 100 is in normal use, the temperature of the battery cell 100 is lower than the preset temperature, the thermal expansion part 150 maintains a natural state or a slightly deformed state based on thermal expansion and contraction, there is a pressure relief cavity between the first wall 113 and the electrode assembly 120, the pressure relief mechanism 115 of the first wall 113 is in a closed state, and the battery cell 100 can maintain normal operation; when the battery cell 100 has thermal runaway, the temperature of the battery cell 100 will exceed (greater than or equal to) the preset temperature, at this time, the gas and other emissions inside the battery cell 100 flow to the pressure relief mechanism 115 through the pressure relief cavity, the pressure relief mechanism 115 is actuated, and the thermal expansion part 150 will expand rapidly and greatly, thereby limiting the electrode assembly 120 from moving under the impact of the emissions. Exemplarily, the thermal expansion part 150 can be a thermal expansion material 151 that undergoes chemical reaction under high temperature, causing the thermal expansion part 150 to expand.

[0104] It can be understood that the rapid expansion of the thermal expansion portion 150 means that the expansion amount of the thermal expansion portion 150 at a preset temperature or above the preset temperature is much greater than the expansion amount of the thermal expansion portion 150 at a temperature below the preset temperature.

[0105] Exemplarily, a thermal expansion portion 150 is provided in the wall body of the circumferential side wall 1111. The inner wall surface at the corresponding position of the wall body and the thermal expansion portion 150 can expand or rupture inwardly under the action of the expansion of the thermal expansion portion 150. For example, the circumferential side wall 1111 can be partially made into a hollow structure, and the thermal expansion material 151 is filled in the hollow structure to form the thermal expansion portion 150, and the wall surface of the surrounding hollow structure facing the electrode assembly 120 is set to expand or rupture. The inner wall surface at the corresponding position of the wall body and the thermal expansion portion 150 can expand or rupture inwardly under the action of the expansion of the thermal expansion portion 150, which means that the inner wall surface can expand synchronously toward the electrode assembly 120 when the thermal expansion portion 150 expands, or the inner wall surface can rupture when the thermal expansion portion 150 expands, thereby increasing the possibility of normal expansion of the thermal expansion portion 150 and reducing the possibility of the thermal expansion portion 150 not expanding adaptively due to the binding effect of the nasal mucus.

[0106] For example, Figure 6 and Figure 7As shown, the inner wall surface of the circumferential side wall 1111 (the surface facing the electrode assembly 120) is provided with a thermal expansion portion 150, and the inner wall surface of the circumferential side wall 1111 can be partially coated with a thermal expansion material 151 to form a thermal expansion material layer, which serves as the thermal expansion portion 150. Optionally, the thermal expansion portion 150 can be arranged in a circle along the circumference of the circumferential side wall 1111.

[0107] For example, Fig.10 As shown, the thermal expansion part 150 may be disposed on the electrode assembly 120 .

[0108] Exemplarily, the outer side of the electrode assembly 120 is provided with an insulating film 140, and the insulating film 140 is arranged in the housing 110, such as Figure 8 and Fig. 9 As shown, the thermal expansion part 150 may be disposed on the insulating film 140 so that the thermal expansion part 150 is located between the electrode assembly 120 and the housing 110. Optionally, the thermal expansion part 150 may be disposed on the outer surface of the insulating film 140 and arranged along the circumference of the insulating film 140.

[0109] Exemplarily, the heat expansion portion 150 may be formed by directly coating a material including the heat expansion substance 151 on the inner wall surface of the housing 110 , the insulating film 140 , or the electrode assembly 120 .

[0110] Exemplarily, the thermal expansion part 150 may also be formed by encapsulating a material including the thermal expansion substance 151 in a flexible sleeve 152 to form an expandable capsule, and then setting the expandable capsule on the housing 111, the insulating film 140 or the electrode assembly 120. It should be noted that when the thermal expansion part 150 is set on the ion movement path of the battery cell 100, for example, when the thermal expansion part 150 is set on the pole piece and the separator 123 (separation film 124) of the lithium-ion battery cell 100, the thermal expansion part 150 can be set so as not to affect the normal movement of lithium ions during the charging and discharging process of the battery cell 100.

[0111] Exemplarily, when the thermal expansion part 150 is disposed on the isolation member 123 (isolation film 124), the porosity of the isolation film 124 is greater than or equal to 20%, and specifically can be about 20% to 50%. The porosity of the isolation film 124 refers to the ratio of the volume of the voids of the isolation film 124 to the total volume of the isolation film 124, the coating layer on the isolation film 124, and the thermal expansion part 150 on the isolation film 124.

[0112] Exemplarily, the heat expansion substance 151 may be calcium gluconate.

[0113] When the temperature is greater than or equal to the preset temperature, the thermal expansion part 150 can be set to expand in one or several directions, or the thermal expansion part 150 can be set to expand freely. In particular, when the temperature of the battery cell 100 is greater than or equal to the preset temperature (at this time, it can be considered that the temperature of the thermal expansion part 150 is greater than or equal to the preset temperature), the thermal expansion part 150 can expand to make the electrode assembly 120 and the circumferential side wall 1111 press against each other in at least one direction (roughly parallel to one of the directions of the first wall 113). When the battery cell 100 is in normal use, there may be a gap between the electrode assembly 120 and the circumferential side wall 1111, and the expansion size of the thermal expansion part 150 in at least one direction (roughly parallel to one of the directions of the first wall 113) may not be less than the gap size between the electrode assembly 120 and the circumferential side wall 1111 in the current state.

[0114] The mutual press fit between the electrode assembly 120 and the circumferential side wall 1111 means that there is a fastening force between the circumferential side wall 1111 and the electrode assembly 120, so that the electrode assembly 120 and the circumferential side wall 1111 can be tightly matched. Optionally, the electrode assembly 120 can directly contact the circumferential side wall 1111 to generate a fastening force, and the electrode assembly 120 and the circumferential side wall 1111 can also indirectly contact each other through the thermal expansion part 150 or the insulating film 140 to generate a fastening force that presses against each other. When the electrode assembly 120 and the circumferential side wall 1111 are pressed against each other, the electrode assembly 120 can be in close contact with the circumferential side wall 1111 (specifically, the electrode assembly 120 and the insulating film 140 can be in close contact with the circumferential side wall 1111 together), so that the electrode assembly 120 is restrained by the circumferential side wall 1111, and the electrode assembly 120 is restricted from moving toward the first wall 113.

[0115] The preset temperature is a pre-set temperature, which is the critical temperature at which the thermal expansion part 150 undergoes a significant expansion. During design, it can be determined based on the temperature at which the battery cell 100 undergoes thermal runaway and the temperature of the battery cell 100 in normal use. The preset temperature can be set to be greater than the maximum temperature of the battery cell 100 in normal use and less than or equal to the minimum temperature at which the battery cell 100 undergoes thermal runaway. The maximum temperature of the battery cell 100 in normal use and the minimum temperature at which the battery cell 100 undergoes thermal runaway can be obtained through experiments during the design phase of the battery cell 100. According to the corresponding preset temperature, the expansion requirement of the thermal expansion part 150 at the preset temperature can be met by adjusting the material ratio and other adaptability of the thermal expansion part 150.

[0116] The temperature at which thermal runaway occurs in the battery cell 100 of the embodiment of the present application is usually higher than the preset temperature. When thermal runaway occurs in the battery cell 100, the temperature of the environment in which the thermal expansion portion 150 is located increases, causing the thermal expansion portion 150 to expand, and the electrode assembly 120 and the circumferential side wall 1111 of the outer shell 110 are pressed against each other. Under the restraining effect of the circumferential side wall 1111, the possibility of the electrode assembly 120 moving toward the first wall 113 is reduced, thereby reducing the possibility of the electrode assembly 120 blocking the pressure relief cavity between the first side wall 1112 and the electrode assembly 120 and the pressure relief mechanism 115, improving the timeliness of the discharge of emissions such as gas generated inside the battery cell 100 from the pressure relief mechanism 115, reducing the possibility of greater harm to the battery cell 100 due to the accumulation of emissions, and reducing the risk of thermal runaway of the battery cell 100.

[0117] According to some embodiments of the present application, optionally, Fig.10 As shown, combined with Figure 11 to Figure 12 As shown, Fig.11 A schematic cross-sectional view of a battery cell according to some embodiments of the present application is shown in FIG. Fig.12 This is a schematic cross-sectional diagram of a battery cell proposed in some embodiments of the present application. A discharge channel 160 is provided between the circumferential side wall 1111 and the electrode assembly 120 , and the thermal expansion portion 150 is configured to avoid a portion of the discharge channel 160 .

[0118] The discharge channel 160 between the circumferential side wall 1111 and the electrode assembly 120 may be formed by a gap between the outer peripheral surface of the electrode assembly 120 (the circumferential outer side surface of the electrode assembly 120) and the circumferential side wall 1111. The discharge cavity may be connected to the interior of the housing 110. Specifically, the discharge cavity may be connected to the region of the electrode assembly 120 away from the first wall 113 and the region of the electrode assembly 120 close to the first wall 113 inside the housing 110. When thermal runaway occurs in the battery cell 100, the discharge at one end away from the first wall 113 may flow to the pressure relief cavity through the discharge channel 160, and then flow to the pressure relief mechanism 115.

[0119] Exemplarily, any position of the outer peripheral surface of the electrode assembly 120 can be clearance-fitted with the circumferential side wall 1111 to form the emission channel 160, and the thermal expansion portion 150 can be set to correspond to a local position of the circumference of the electrode assembly 120. In this way, the thermal expansion portion 150 can avoid part of the emission channel 160. When the thermal expansion portion 150 expands at a temperature greater than or equal to a preset temperature, the emission channel 160 staggered from the thermal expansion portion 150 can maintain the passing performance of the emission, and the position of the electrode assembly 120 corresponding to the thermal expansion portion 150 can be pressed and fitted with the circumferential side wall 1111 to restrain the electrode assembly 120 and reduce the possibility of movement of the electrode assembly 120.

[0120] Exemplarily, the outer circumferential surface of the electrode assembly 120 and a local position of the circumferential side wall 1111 are provided with the exhaust channels 160 , and the thermal expansion portion 150 may be staggered with all the exhaust channels 160 to avoid all the exhaust channels 160 .

[0121] In the battery cell 100 of this embodiment, the thermal expansion portion 150 is configured to avoid at least a portion of the emission channel 160. When thermal runaway occurs in the battery, the emissions can flow to the pressure relief mechanism 115 through the emission channel 160 avoided by the thermal expansion portion 150. While reducing the movement of the electrode assembly 120, the timeliness of emission discharge is provided, the possibility of greater harm to the battery cell 100 due to the accumulation of emissions is reduced, and the risk of thermal runaway of the battery cell 100 is reduced.

[0122] According to some embodiments of the present application, optionally, the discharge channel 160 includes a first discharge channel 161, and the first discharge channel 161 is provided on one side of the electrode assembly 120 along the first direction X. When the thermal expansion portion 150 is expanded, the electrode assembly 120 and the circumferential side wall 1111 are pressed against each other along the second direction Y. The first direction X intersects with the second direction Y, and the first direction X and the second direction Y intersect at the arrangement direction Z of the first wall 113 and the electrode assembly 120, respectively.

[0123] Exemplarily, the first direction X and the second direction Y are both substantially perpendicular to the first wall 113 and the arrangement direction Z of the electrode assembly 120, that is, the first direction X and the second direction Y are both substantially parallel to the first wall 113. The first direction X and the second direction Y may be substantially perpendicular.

[0124] The first exhaust channel 161 may be a region corresponding to the first direction X of the electrode assembly 120 among all the exhaust channels 160 .

[0125] For example, the first exhaust passage 161 may be disposed at a corner of the curved portion 1204 .

[0126] Exemplarily, the exhaust channel 160 may further include a second exhaust channel 162 located at one side of the electrode assembly 120 in the second direction Y.

[0127] The direction in which the circumferential side wall 1111 and the electrode assembly 120 are pressed against each other (i.e., the second direction Y) intersects with the first direction X. Thus, in the event of thermal runaway of the battery cell 100, the first discharge channel 161 disposed on the first direction X side of the electrode assembly 120 can remain connected, thereby reducing the movement of the electrode assembly 120 and providing timeliness of emission discharge, thereby reducing the possibility of greater harm to the battery cell 100 due to the accumulation of emissions and reducing the risk of thermal runaway of the battery cell 100.

[0128] According to some embodiments of the present application, optionally, Figures 3 to 5 , Figures 10 to 12 As shown, the electrode assembly 120 includes a straight portion 1203 and a curved portion 1204, the circumferential side wall 1111 includes a first side wall 1112 arranged opposite to the straight portion 1203 and a second side wall 1113 arranged opposite to the curved portion 1204, the first discharge channel 161 is arranged between the curved portion 1204 and the second side wall 1113, a thermal expansion portion 150 is arranged on the first side wall 1112, and / or a thermal expansion portion 150 is arranged between the first side wall 1112 and the straight portion 1203, and / or a thermal expansion portion 150 is arranged on the straight portion 1203.

[0129] Figure 4 The dotted line in may represent a boundary between the straight portion 1203 and the curved portion 1204 .

[0130] The straight portion 1203 of the electrode assembly 120 is a portion extending substantially in a straight line, and the curved portion 1204 of the electrode assembly 120 is a portion extending in a curved manner. The straight portion 1203 and the curved portion 1204 of the electrode assembly 120 may be arranged and connected to each other along a direction Z perpendicular to the first wall 113 and the electrode assembly 120. For example, the straight portion 1203 and the curved portion 1204 of the electrode assembly 120 may be arranged and connected to each other in sequence along a first direction X. The first side wall 1112 of the housing 110 is adjacent to and connected to the second side wall 1113.

[0131] For example, Figures 3 to 5 , and combined with Figures 10 to 12 As shown, the battery cell 100 may be a square shell battery cell, and the shape of its shell 110 and electrode assembly 120 are both roughly square, and the thickness surface of the battery cell 100 is set as an arc surface, and the width surface of the battery cell 100 is set as a plane. The area corresponding to the plane of the electrode assembly 120 is a straight line portion 1203, and the area corresponding to the arc surface of the electrode assembly 120 is a curved portion 1204. The first side wall 1112 of the circumferential side wall 1111 can be set as a plane wall, and the second side wall 1113 can be set as an arc wall.

[0132] It should be noted that, in some other embodiments, the width surface of the battery cell 100 may also be set as an arc surface, while the thickness surface of the battery cell 100 is set as a flat surface.

[0133] For example, a thermal expansion portion 150 may be disposed within the wall of the first side wall 1112. Fig.11 As shown, a thermal expansion portion 150 may also be disposed on the inner wall surface of the first side wall 1112 (the side surface of the first side wall 1112 facing the electrode assembly 120 ).

[0134] For example, Fig.12As shown, a thermal expansion portion 150 may be provided at a portion of the insulating film 140 between the first side wall 1112 and the straight portion 1203 . The thermal expansion portion 150 may be provided in the film body of the insulating film 140 or on a surface on any side of the insulating film 140 .

[0135] For example, Fig.10 As shown, the region where the straight portion 1203 of the electrode assembly 120 is formed may be provided with a thermal expansion portion 150. Optionally, the thermal expansion portion 150 may be provided on the outer peripheral surface of the straight portion 1203 of the electrode assembly 120 (refer to the first side surface 1201). The thermal expansion portion 150 may also be provided on the separator 123, the positive electrode 121 and / or the negative electrode 122 of the electrode assembly 120 corresponding to the straight portion 1203, or between the separator 123 and the positive electrode 121, or between the separator 123 and the negative electrode 122.

[0136] In the battery cell 100 of this embodiment, the curved portion 1204 of the electrode assembly 120 and the second side wall 1113 of the housing 110 are curved, so the first discharge channel 161 between the two is easier to form and easier to maintain the passability of the discharge. The thermal expansion portion 150 is arranged on the first side wall 1112, or between the first side wall 1112 and the straight portion 1203, or on the straight portion 1203. The thermal expansion portion 150 can avoid the first discharge channel 161 between the curved portion 1204 and the second side wall 1113. When the temperature is greater than or equal to the preset temperature, the thermal expansion portion 150 expands to make the first wall 113 and the straight portion 1203 press against each other to restrain the electrode assembly 120 from moving toward the first wall 113. Since the straight portion 1203 and the first wall 113 corresponding to the area where the thermal expansion portion 150 is located are roughly flat, the probability of the electrode assembly 120 and the circumferential side wall 1111 being tightly pressed together after the thermal expansion portion 150 expands can be increased, and the thermal expansion portion 150 is designed to be more expandable and controllable.

[0137] According to some embodiments of the present application, optionally, Figure 3 , Figures 10 to 12 As shown, the electrode assembly 120 includes a first side surface 1201 and a second side surface 1202, the area of ​​the first side surface 1201 is larger than that of the second side surface 1202, the circumferential side wall 1111 includes a first side wall 1112 and a second side wall 1113, the first side wall 1112 and the first side surface 1201 are arranged opposite to each other, the second side wall 1113 and the second side surface 1202 are arranged opposite to each other, the first discharge channel 161 is arranged between the second side surface 1202 and the second side wall 1113, the first side wall 1112 is provided with a thermal expansion portion 150, and / or the thermal expansion portion 150 is provided between the first side wall 1112 and the first side surface 1201, and / or the thermal expansion portion 150 is provided on the first side surface 1201, and / or the thermal expansion portion 150 is provided in the electrode assembly 120.

[0138] The first side surface 1201 and the second side surface 1202 of the electrode assembly 120 may be two adjacent and interconnected side surfaces of the electrode assembly 120 , the first side surface 1201 may be a width surface of the electrode assembly 120 , and the second side surface 1202 may be a thickness surface of the electrode assembly 120 .

[0139] For example, Figure 3 , Figures 10 to 12 As shown, the second side surface 1202 can be set as an arc surface, so that the area of ​​the electrode assembly 120 corresponding to the second side surface 1202 can also be roughly understood as the curved portion 1204; the first side surface 1201 can be set as a plane, so that the area of ​​the electrode assembly 120 corresponding to the first side surface 1201 can be roughly understood as the straight portion 1203. In this exemplary manner, the first side wall 1112 corresponding to the first side surface 1201 and the first side wall 1112 corresponding to the straight portion 1203 are the same side wall, and the second side wall 1113 corresponding to the second side surface 1202 and the second side wall 1113 corresponding to the curved portion 1204 are the same side wall.

[0140] It should be noted that, in some other embodiments, the first side surface (width surface) of the battery cell 100 can also be set as an arcuate surface, and the second side surface (thickness surface) of the battery cell 100 can be set as a plane. In this case, the first side wall corresponding to the first side surface and the first side wall corresponding to the straight portion can be different side walls, and the second side wall corresponding to the second side surface and the second side wall corresponding to the curved portion can be different side walls.

[0141] In the battery cell 100 of this embodiment, the heat expansion part 150 is arranged on the first side wall 1112, and / or between the first side wall 1112 and the first side surface 1201, and / or in the first side surface 1201 and / or in the electrode assembly 120. The heat expansion part 150 can avoid the first exhaust channel 161 between the second side surface 1202 and the second side wall 1113. When the temperature is greater than or equal to the preset temperature, the heat expansion part 150 expands so that the first wall 113 and the first side surface 1201 with a larger area can be pressed against each other to restrain the electrode assembly 120 from moving toward the first wall 113. Since the area of ​​the first side surface 1201 and the first wall 113 corresponding to the area where the heat expansion part 150 is located is larger, the probability of the electrode assembly 120 and the circumferential side wall 1111 being tightly pressed against each other after the heat expansion part 150 expands can be increased, and the heat expansion part 150 is designed to be more expandable and controllable.

[0142] According to some embodiments of the present application, optionally, Figure 3 , and combined with Figure 8 , Fig. 9 and Fig.12As shown, the battery cell 100 also includes an insulating film 140, which is coated on the outside of the electrode assembly 120 and is located in the outer shell 110, and at least a portion of the film body of the insulating film 140 located between the electrode assembly 120 and the circumferential side wall 1111 is set as a thermal expansion portion 150 and / or the surface of at least a portion of the film body of the insulating film 140 located between the electrode assembly 120 and the circumferential side wall 1111 is set with a thermal expansion portion 150.

[0143] Exemplarily, the insulating film 140 is located in the film body between the electrode assembly 120 and the circumferential side wall 1111, and the surface facing the electrode assembly 120 may be provided with a thermal expansion portion 150, and the surface facing away from the electrode assembly 120 (the surface facing the housing 110) may also be provided with a thermal expansion portion 150. For example, the surface of the insulating film 140 facing the electrode assembly 120 and / or the surface of the insulating film 140 facing away from the electrode assembly 120 is coated with a thermal expansion material 151 to form a thermal expansion material layer, and the thermal expansion material layer serves as the thermal expansion portion 150. In this way, the insulating film 140 as a whole can also be considered as a composite film structure.

[0144] Exemplarily, the film body of the insulating film 140 located between the electrode assembly 120 and the circumferential side wall 1111 may be configured as a composite film structure having a thermal expansion substance 151 .

[0145] In the battery cell 100 of the embodiment of the present application, when thermal runaway occurs in the battery cell 100, the temperature of the environment in which the heat expansion portion 150 on the insulating film 140 is located increases, causing the heat expansion portion 150 to swell, and the electrode assembly 120, the insulating film 140 and the circumferential side wall 1111 of the outer shell 110 are pressed and fitted against each other. Under the restraining effect of the circumferential side wall 1111, the possibility of the electrode assembly 120 moving toward the first wall 113 is reduced, thereby reducing the possibility of the electrode assembly 120 blocking the pressure relief cavity between the first side wall 1112 and the electrode assembly 120 and the pressure relief mechanism 115, improving the timeliness of the discharge of emissions such as gas generated inside the battery cell 100 from the pressure relief mechanism 115, reducing the possibility of greater harm to the battery cell 100 due to the accumulation of emissions, and reducing the risk of thermal runaway of the battery cell 100.

[0146] According to some embodiments of the present application, optionally, at least a portion of the insulating film 140 located between the electrode assembly 120 and the circumferential side wall 1111 is configured as a composite film structure having a thermal expansion substance 151 , and the composite film structure forms a thermal expansion portion 150 .

[0147] The composite film structure of the film body of the insulating film 140 can meet the performance requirements of the battery cell 100 in a normal use state, and can expand when the temperature is greater than or equal to a preset temperature.

[0148] For example, the thermal expansion material 151 may be mixed with other materials forming the insulating film 140 and then processed to form a composite film structure.

[0149] For example, the heat expansion material 151 and other materials forming the insulating film 140 may be coated layer by layer, and different materials may form a composite film structure with a layer structure.

[0150] For example, a receiving cavity may be provided on the film body of the insulating film 140 , and the heat expansion material 151 may be filled into the receiving cavity to form a composite film structure.

[0151] The battery cell 100 of the present embodiment, by setting the film body of the insulating film 140 at least partially as a composite film structure having a heat-expanding material 151, when the battery cell 100 has a thermal runaway, the temperature of the environment where the heat-expanding portion 150 is located increases, causing the heat-expanding portion 150 to expand, and the electrode assembly 120, the insulating film 140 and the circumferential side wall 1111 of the shell 110 are pressed against each other. Under the restraining effect of the circumferential side wall 1111, the possibility of the electrode assembly 120 moving toward the first wall 113 is reduced, thereby reducing the possibility of the electrode assembly 120 blocking the pressure relief cavity between the first side wall 1112 and the electrode assembly 120 and the pressure relief mechanism 115, improving the timeliness of the discharge of emissions such as gas generated inside the battery cell 100 from the pressure relief mechanism 115, reducing the possibility of greater harm to the battery cell 100 due to the accumulation of emissions, and reducing the risk of thermal runaway of the battery cell 100.

[0152] According to some embodiments of the present application, optionally, a accommodating cavity is provided in the portion of the film body of the insulating film 140 located between the electrode assembly 120 and the circumferential side wall 1111, and a heat expansion material 151 is provided in the accommodating cavity to form a heat expansion portion 150, and the positions corresponding to the insulating film 140 and the heat expansion portion 150 are configured to be able to extend, expand or rupture under the action of the expansion of the heat expansion portion 150.

[0153] The membrane body may be provided with an injection hole, through which the heat expansion material 151 may be injected into the accommodating cavity. After the heat expansion material 151 is injected, the injection hole may be sealed by glue or the like.

[0154] Exemplarily, the insulating film 140 may be made into a hollow structure, and a heat expansion material 151 may be filled in the hollow structure to form a heat expansion portion 150. The position corresponding to the insulating film 140 and the heat expansion portion 150 is set to be able to expand or rupture under the effect of the expansion of the heat expansion portion 150, which means that the insulating film 140 may expand synchronously when the heat expansion portion 150 expands, or the insulating film 140 may rupture when the heat expansion portion 150 expands, thereby increasing the possibility of normal expansion of the heat expansion portion 150 and reducing the possibility that the heat expansion portion 150 does not expand adaptively due to the restraining effect of the insulating film 140.

[0155] The battery cell 100 of this embodiment forms a composite membrane structure by filling the thermal expansion part 150 in the membrane body of the insulating film 140. When the battery cell 100 has thermal runaway, the temperature of the environment where the thermal expansion part 150 is located increases, causing the thermal expansion part 150 to expand, and the electrode assembly 120, the insulating film 140 and the circumferential side wall 1111 of the shell 110 are pressed against each other. Under the restraining effect of the circumferential side wall 1111, the possibility of the electrode assembly 120 moving toward the first wall 113 is reduced, thereby reducing the possibility of the electrode assembly 120 blocking the pressure relief cavity between the first side wall 1112 and the electrode assembly 120 and the pressure relief mechanism 115, improving the timeliness of the discharge of emissions such as gas generated inside the battery cell 100 from the pressure relief mechanism 115, reducing the possibility of greater harm to the battery cell 100 due to the accumulation of emissions, and reducing the risk of thermal runaway of the battery cell 100.

[0156] According to some embodiments of the present application, optionally, Figures 13 to 15 As shown, Fig.13 is a schematic cross-sectional diagram of an electrode assembly according to some embodiments of the present application. Fig.14 is a schematic cross-sectional diagram of an electrode assembly according to some embodiments of the present application. Fig.15 This is a cross-sectional schematic diagram of an electrode assembly of some embodiments of the present application, wherein the electrode assembly 120 includes a positive electrode 121, a negative electrode 122 and an isolation member 123, wherein the isolation member 123 is disposed between the negative electrode 122 and the positive electrode 121, and the isolation member 123 is used to electrically insulate adjacent positive electrodes 121 and negative electrodes 122, and to transmit ions between adjacent positive electrodes 121 and negative electrodes 122, wherein a thermal expansion portion 150 is disposed on the positive electrode 121, and / or a thermal expansion portion 150 is disposed on the negative electrode 122, and / or a thermal expansion portion 150 is disposed on the isolation member 123, and / or a thermal expansion portion 150 is disposed between the positive electrode 121 and the isolation member 123, and / or a thermal expansion portion 150 is disposed between the negative electrode 122 and the isolation member 123.

[0157] For example, Fig.13 As shown, the positive electrode 121 may be provided with a thermal expansion portion 150. Optionally, the thermal expansion portion 150 on the positive electrode 121 is provided on the region where the positive electrode 121 forms the straight portion 1203. Naturally, the positive electrode 121 may also selectively provide the thermal expansion portion 150 in other regions.

[0158] For example, Fig.14 As shown, the negative electrode 122 may be provided with a thermal expansion portion 150. Optionally, the thermal expansion portion 150 on the negative electrode 122 is provided on the region where the negative electrode 122 forms the straight portion 1203. Naturally, the negative electrode 122 may also selectively be provided with a thermal expansion portion 150 in other regions.

[0159] For example, Fig.15 As shown, the isolating member 123 may be provided with a thermal expansion portion 150. Optionally, the thermal expansion portion 150 on the isolating member 123 is provided on the region where the isolating member 123 forms the straight portion 1203. Naturally, the isolating member 123 may also selectively provide the thermal expansion portion 150 in other regions.

[0160] For example, Fig.13 As shown, a thermal expansion portion 150 may be disposed between the positive electrode 121 and the separator 123 .

[0161] For example, Fig.14 As shown, a thermal expansion portion 150 may be disposed between the negative electrode 122 and the separator 123 .

[0162] The battery cell 100 of the present embodiment is provided with a heat expansion portion 150 on the electrode assembly 120. When the battery cell 100 has thermal runaway, the temperature of the environment where the heat expansion portion 150 is located increases, causing the heat expansion portion 150 to expand. The electrode assembly 120, the insulating film 140 and the circumferential side wall 1111 of the shell 110 are pressed against each other. Under the restraining effect of the circumferential side wall 1111, the possibility of the electrode assembly 120 moving toward the first wall 113 is reduced, thereby reducing the possibility of the electrode assembly 120 blocking the pressure relief cavity between the first side wall 1112 and the electrode assembly 120 and the pressure relief mechanism 115, improving the timeliness of the discharge of emissions such as gas generated inside the battery cell 100 from the pressure relief mechanism 115, reducing the possibility of greater harm to the battery cell 100 due to the accumulation of emissions, and reducing the risk of thermal runaway of the battery cell 100.

[0163] According to some embodiments of the present application, optionally, at least a portion of at least one of the positive electrode 121 , the negative electrode 122 , and the separator 123 is a composite structure having a thermal expansion material 151 , and the composite structure forms a thermal expansion portion 150 .

[0164] Exemplarily, the positive electrode 121 may be a composite structure having a thermal expansion material 151. For example, the surface of the positive electrode 121 may be provided with a thermal expansion portion 150, for example, the surface of the positive electrode 121 is coated with a thermal expansion material 151 to form a thermal expansion material layer, and the positive electrode 121 of such a structure may be considered as a composite structure having a thermal expansion material 151; for another example, the surface of the positive electrode collector is sequentially coated with a thermal expansion material 151 and a positive electrode active material to form different layer structures, and the positive electrode 121 of such a structure may also be considered as a composite structure having a thermal expansion material 151; for another example, the positive electrode active material and the thermal expansion material 151 are mixed and coated on the positive electrode collector, and the positive electrode 121 may also be considered as a composite structure having a thermal expansion material 151; for another example, the thermal expansion material 151 is filled inside the active material layer of the current collector of the positive electrode 121 or inside the current collector, and the positive electrode 121 may also be considered as a composite structure having a thermal expansion material 151.

[0165] Exemplarily, the negative electrode 122 may be a composite structure having a thermal expansion material 151. For example, the surface of the negative electrode 122 may be provided with a thermal expansion portion 150, for example, the surface of the negative electrode 122 is coated with a thermal expansion material 151 to form a thermal expansion material layer, and the negative electrode 122 of such a structure may be considered as a composite structure having a thermal expansion material 151; for another example, the surface of the negative electrode current collector is sequentially coated with a thermal expansion material 151 and a negative electrode active material to form different layer structures, and the negative electrode 122 of such a structure may also be considered as a composite structure having a thermal expansion material 151; for another example, the negative electrode active material and the thermal expansion material 151 are mixed and coated on the negative electrode current collector, and the negative electrode 122 may also be considered as a composite structure having a thermal expansion material 151; for another example, the thermal expansion material 151 is filled inside the active material layer of the current collector of the negative electrode 122 or inside the current collector, and the negative electrode 122 may also be considered as a composite structure having a thermal expansion material 151.

[0166] Exemplarily, the separator 123 may be a composite structure having a thermal expansion material 151. For example, the surface of the separator 123 may be provided with a thermal expansion portion 150. For example, the surface of the separator 123 is coated with a thermal expansion material 151 to form a thermal expansion material layer. The separator 123 of this structure may be considered to be a composite structure having a thermal expansion material 151. For another example, after the active material of the separator 123 is mixed with the thermal expansion material 151, the separator 123 is processed to form the separator 123. The separator 123 may also be considered to be a composite structure having a thermal expansion material 151. For another example, the inside of the body of the separator 123 is filled with a thermal expansion material 151. The separator 123 may also be considered to be a composite structure having a thermal expansion material 151. The thermal expansion portion 150 is provided on the separator 123, which can not only reduce the possibility of movement of the battery cell 100 by thermal expansion, but also reduce the short-circuit site between the positive electrode 121 and the negative electrode 122 due to the expansion of the separator 123, thereby reducing the failure probability.

[0167] When the surface of the separator 123 is provided with a heat expansion part 150, the heat expansion material 151 can be coated on one side or both sides of the separator 123, and the heat expansion material 151 coated on the surface of the separator 124 can be physically mixed with inorganic and organic particles and then coated on the surface of the separator 124, or an organic polymer material can be used to form a flexible sleeve 152, and the heat expansion particles are coated on the surface of the separator 124. The heat material coated on the surface of the separator 123 can not only expand thermally after being heated to reduce the possibility of movement of the battery cell 100, but also reduce the short-circuit sites between the positive electrode 121 and the negative electrode 122, thereby reducing the failure probability.

[0168] The battery cell 100 of this embodiment has at least one of the positive electrode 121, the negative electrode 122 and the separator 123 as a composite structure having a heat-expanding material 151. When the battery cell 100 has a thermal runaway, the temperature of the environment where the heat-expanding portion 150 is located increases, causing the heat-expanding portion 150 of the composite structure to expand. The electrode assembly 120, the insulating film 140 and the circumferential side wall 1111 of the shell 110 are pressed against each other. Under the restraining effect of the circumferential side wall 1111, the possibility of the electrode assembly 120 moving toward the first wall 113 is reduced, thereby reducing the possibility of the electrode assembly 120 blocking the pressure relief cavity between the first side wall 1112 and the electrode assembly 120 and the pressure relief mechanism 115, improving the timeliness of the discharge of emissions such as gas generated inside the battery cell 100 from the pressure relief mechanism 115, reducing the possibility of greater harm to the battery cell 100 due to the accumulation of emissions, and reducing the risk of thermal runaway of the battery cell 100.

[0169] According to some embodiments of the present application, optionally, a thermal expansion portion 150 is provided on a surface of the positive electrode 121 , a surface of the negative electrode 122 , and a surface of the separator 123 .

[0170] For example, Fig.13 As shown, a thermal expansion portion 150 may be disposed on the surface of the positive electrode 121 , wherein the thermal expansion portion 150 may be disposed on a single side surface or both side surfaces of the positive electrode 121 .

[0171] For example, Fig.14 As shown, a thermal expansion portion 150 may be disposed on the surface of the negative electrode 122 , wherein the thermal expansion portion 150 may be disposed on a single side surface or both side surfaces of the negative electrode 122 .

[0172] For example, Fig.15 As shown, a thermal expansion portion 150 may be disposed on a surface of the isolation member 123 , wherein the thermal expansion portion 150 may be disposed on a single side surface or both sides of the isolation member 123 .

[0173] In this embodiment, thermal expansion parts 150 are provided on the surface of the positive electrode 121, the surface of the negative electrode 122 and / or the surface of the isolation member 123. These expansion parts can not only expand at a temperature greater than or equal to a preset temperature to reduce the possibility of movement of the battery cell 100, but also can reduce the short-circuit points between the positive electrode 121 and the negative electrode 122 due to their expansion performance, thereby reducing the failure probability.

[0174] According to some embodiments of the present application, optionally, the battery cell 100 also includes an insulating film 140, which is coated on the outside of the electrode assembly 120 and is located inside the outer shell 110; a thermal expansion portion 150 is formed on the circumferential side wall 1111, the insulating film 140, and the electrode assembly 120 by coating.

[0175] Specifically, the inner wall surface of the circumferential side wall 1111, the surface of the insulating film 140 facing the electrode assembly 120, the surface of the insulating film 140 away from the electrode assembly 120, the outer surface of the insulating film 140 electrode assembly 120 and / or the positive electrode 121, the isolation member 123, and the negative electrode 122 of the electrode assembly 120 can all be coated to form a thermal expansion portion 150.

[0176] Exemplarily, the thermal expansion portion 150 can be formed by coating a binder and a thermal expansion material 151 on the corresponding carrier (circumferential side wall 1111, insulating film 140, outer surface of electrode assembly 120, positive electrode 121, negative electrode 122 or separator 123). The binder and the thermal expansion material 151 can be mixed and then coated to form an expansion material layer, or the adhesive can be coated first and then the thermal expansion material 151 can be coated on the binder. The main function of the binder is to fix the thermal expansion material 151. The thermal expansion material 151 can be coated directly, or the thermal expansion material 151 can be wrapped by a flexible sleeve 152 and then coated.

[0177] In this embodiment, the thermal expansion portion 150 is formed by coating, which is easy to process and is not likely to affect the performance of the carrier (circumferential side wall 1111, insulating film 140, outer surface of electrode assembly 120, positive electrode 121, negative electrode 122 or separator 123).

[0178] According to some embodiments of the present application, optionally, the material of the thermal expansion part 150 includes an adhesive and a thermal expansion substance 151 .

[0179] The main function of the binder is to fix the thermal expansion material 151. The binder can be glue. The adhesive has a certain high temperature resistance. When the battery cell 100 is in normal use, the adhesive is not easy to fail. When the thermal expansion part 150 is set on the ion movement path of the battery cell 100, the adhesive should not affect the permeability of the ions. The binder and the thermal expansion material 151 can be mixed to form a mixture, and then coated together to form an expansion material layer. The binder can also be coated first to form an adhesive layer, and then the thermal expansion material 151 is coated on the adhesive layer. Among them, the thermal expansion material 151 can be directly coated, or the thermal expansion material 151 can be wrapped by the flexible sleeve 152 and then coated with the binder.

[0180] The heat expansion substance 151 may include calcium gluconate.

[0181] The heat expansion part 150 of the battery cell 100 of this embodiment comprises a binder and a heat expansion material 151 . The heat expansion material 151 can make the heat expansion part 150 expand at a temperature greater than or equal to a preset temperature, and the binder can make the heat expansion part 150 have better fixing stability.

[0182] It should be noted that, in some other embodiments, the thermal expansion portion 150 may not be fixed by a binder. For example, the thermal expansion portion 150 is fixed by the clamping action of adjacent carriers. For example, the thermal expansion portion 150 between the positive electrode 121 and the insulating member 123 may be fixed by the clamping action of the positive electrode 121 and the insulating member 123.

[0183] According to some embodiments of the present application, optionally, Fig.16 As shown, Fig.16 This is a schematic diagram of a heat expansion portion according to some embodiments of the present application. The heat expansion portion 150 includes a flexible sleeve 152 and a heat expansion material 151 . The flexible sleeve 152 is coated on the outside of the heat expansion material 151 .

[0184] The flexible sleeve 152 may be configured to expand outwardly and extend synchronously with the expansion of the heat-expandable substance 151 , or may be configured to rupture when the heat-expandable substance 151 expands, so that the heat-expandable portion 150 may expand when the heat-expandable substance 151 expands.

[0185] The heat expansion part 150 may be wrapped with a plurality of heat expansion materials 151 and a flexible cover 152 .

[0186] The thermal expansion part 150 of the battery cell 100 of this embodiment wraps the thermal expansion material 151 with the flexible sleeve 152, which is easy to process, and the thermal expansion part 150 of this structure can be expanded or ruptured by directional expansion of the flexible sleeve 152, so that the thermal expansion part 150 is concentrated in a specific direction. For example, the expansion coefficient of the flexible sleeve 152 along the second direction Y can be set to be greater than the expansion coefficient of the first direction X. In this way, under the same internal pressure, the amount of expansion of the flexible sleeve 152 in the second direction Y can be greater than the expansion amount in the first direction X, so that the thermal expansion part 150 is mainly deformed in the second direction Y to expand.

[0187] According to some embodiments of the present application, optionally, the heat expansion portion 150 includes a heat expansion substance 151, and the heat expansion substance 151 includes calcium gluconate; and / or, the preset temperature ranges from 80°C to 130°C.

[0188] The preset temperature can be set to 80℃ (degrees Celsius), 81℃, 82℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, 130℃.

[0189] The preset temperature ranges from 80°C to 100°C. When the battery cell 100 is in normal use, the thermal expansion part 150 is not easy to expand and affect the performance of the battery cell 100. When the battery cell 100 has thermal runaway, the thermal expansion part 150 can expand in time to limit the movement of the electrode assembly 120.

[0190] Calcium gluconate, as the thermal expansion material 151, has little effect on the performance of the battery cell 100 and has good thermal expansion. In the battery cell 100 of this embodiment, the thermal expansion material 151 of the thermal expansion part 150 includes calcium gluconate, which can reduce the possibility of the electrode assembly 120 blocking the pressure relief channel between the first side wall 1112 and the electrode assembly 120 and the pressure relief mechanism 115 on the basis of maintaining good performance of the battery cell 100, improve the timeliness of the discharge of the gas and other emissions generated inside the battery cell 100 from the pressure relief mechanism 115, reduce the possibility of greater harm to the battery cell 100 due to the accumulation of emissions, and reduce the risk of thermal runaway of the battery cell 100.

[0191] According to some embodiments of the present application, optionally, the preset temperature is set to 80°C.

[0192] In other words, when the temperature of the thermal expansion part 150 is equal to or greater than 80 degrees, the thermal expansion part 150 will expand rapidly, causing the electrode assembly 120 to press against the circumferential side wall 1111. When the preset temperature is set to 80°C, when the battery cell 100 is in normal use, the thermal expansion part 150 is not likely to expand and affect the performance of the battery cell 100, and when the battery cell 100 has thermal runaway, the thermal expansion part 150 can expand in time to limit the movement of the electrode assembly 120.

[0193] According to some embodiments of the present application, optionally, the battery cell 100 also includes an insulating film 140, which is coated on the outside of the electrode assembly 120 and is located inside the shell 110; when the thermal expansion portion 150 is expanded, the electrode assembly 120 and the circumferential side wall 1111 are pressed against each other along the second direction Y. When the temperature is lower than a preset temperature, the sum of the gap size between the electrode assembly 120 and the insulating film 140 and the gap size between the insulating film 140 and the circumferential side wall 1111 along the second direction Y is H. When the temperature is greater than or equal to the preset temperature, the total expansion size of the electrode assembly 120, the insulating film 140 and the thermal expansion portion 150 along the second direction Y is greater than H, and the second direction Y intersects with the first wall 113 and the arrangement direction Z of the electrode assembly 120.

[0194] The second direction Y of this embodiment may be any direction intersecting with the arrangement direction Z of the first wall 113 and the electrode assembly 120. Figures 3 to 15 As shown, in some implementations, the second direction Y is taken as an example as the thickness direction of the battery cell 100 .

[0195] When the temperature is lower than the preset temperature, the battery cell 100 is in normal use. When the temperature is higher than or equal to the preset temperature, the temperature of the battery cell 100 is usually abnormal, and the battery cell 100 has thermal runaway or has the potential to have thermal runaway.

[0196] In the state of being lower than the preset temperature, along the second direction Y, the gap size between the electrode assembly 120 and the insulating film 140, also H, can be understood as the size of the expandable space of the electrode assembly 120 along the second direction Y. Specifically, it refers to the total size of the gap between the electrode assembly 120 and the shell 110 along the second direction Y, which is equal to the size h1 of the inner wall surface of the shell 110 along the second direction Y minus the size h2 of the electrode assembly 120 itself along the second direction Y (if there are multiple electrode assemblies 120, here is the total size of multiple electrode assemblies 120), minus twice the thickness h3 of the insulating film 140 along the second direction Y. When designing the battery cell 100, the value of H can ignore the thickness h4 of the thermal expansion part 150 along the second direction Y.

[0197] In some other embodiments, when the thermal expansion portion 150 is disposed between the circumferential side wall 1111 and the insulating film 140 or between the insulating film 140 and the electrode assembly 120, in order to accurately calculate the value of H, on the basis of the above, the thickness h4 of the thermal expansion portion 150 along the second direction Y can also be subtracted, that is, H=h1-h2-h3*2-h4. It should also be noted that the value of h4 is the total size of the thermal expansion portion 150 along the second direction Y.

[0198] In the case of a temperature greater than or equal to a preset temperature, the total expansion size of the electrode assembly 120, the insulating film 140 and the thermal expansion portion 150 along the second direction Y can be understood as the sum of the expansion size of the electrode assembly 120 relative to itself in a state less than the preset temperature along the second direction Y, the expansion size of the insulating film 140 relative to itself in a state less than the preset temperature along the second direction Y, and the expansion size of the thermal expansion portion 150 relative to itself in a state less than the preset temperature along the second direction Y. These expansion sizes can be obtained by setting the electrode assembly 120 in an environment equal to or greater than the preset temperature and conducting experiments before designing the battery cell 100, that is, the set size of the thermal expansion portion 150 of the battery cell 100 can be obtained through experiments.

[0199] Optionally, the total expansion size of the electrode assembly 120, the insulating film 140 and the thermal expansion portion 150 along the second direction Y may be 1.05 times, 1.1 times, 1.15 times, 1.2 times, 1.5 times, 2 times, or 3 times of H. The total expansion size of the electrode assembly 120, the insulating film 140 and the thermal expansion portion 150 along the second direction Y may not exceed 5 times of H, so as to reduce the possibility of damage caused by excessive expansion, which may cause serious stress on the housing 110. Optionally, in some implementations, along the second direction Y, the total thickness of the electrode assembly 120 (including the thermal expansion portion 150) is h, the expansion ratio of the thermal expansion portion 150 is β, the original thickness of the thermal expansion portion 150 is t when the temperature is less than the preset temperature, and the expanded thickness of the thermal expansion portion 150 is T when the temperature is greater than or equal to the preset temperature, β=(Tt) / t*100%. The expandable size of the electrode assembly 120 along the second direction Y is H (the calculation formula is the size of the inner wall surface of the shell 110 along the second direction Y minus the size of the electrode assembly 120 itself along the second direction Y (when there are multiple electrode assemblies 120, the size of the electrode assembly 120 itself along the second direction Y is equal to the thickness of one electrode assembly 120 itself multiplied by the number of electrode assemblies 120), and minus the size occupied by the insulating film 140 in the second direction Y). In order to reduce the blockage of the pressure relief mechanism 115 and the exhaust channel caused by upward movement when the battery cell 100 has thermal runaway, the three can satisfy h*β≥1.1H. It should be noted that the upper limit of h*β may be less than or equal to 5 times of H, so as to reduce the possibility of excessive expansion, which may cause the housing 110 to be severely stressed and cause harm.

[0200] In this embodiment, by making the total expansion size of the electrode assembly 120, the insulating film 140 and the thermal expansion part 150 in the second direction Y greater than H, after reaching the preset temperature, the thermal expansion part 150 can expand rapidly so that there is no free gap in the second direction Y of the electrode assembly 120, and the electrode assembly 120 is tightly fitted with the shell 110. In the case of thermal runaway of the battery cell 100, the restraining effect of the circumferential side wall 1111 on the electrode assembly 120 is improved, and the possibility of the electrode assembly 120 moving toward the first wall 113 is reduced, thereby reducing the possibility of the electrode assembly 120 blocking the pressure relief cavity between the first side wall 1112 and the electrode assembly 120 and the pressure relief mechanism 115, improving the timeliness of the discharge of emissions such as gas generated inside the battery cell 100 from the pressure relief mechanism 115, reducing the possibility of greater harm to the battery cell 100 due to the accumulation of emissions, and reducing the risk of thermal runaway of the battery cell 100.

[0201] like Figure 3 As shown, combined with Figure 6 , Figure 7 and Fig.11As shown, this embodiment provides a battery cell 100, which is a square shell battery cell. The battery cell 100 includes a shell 110, an insulating film 140 and an electrode assembly 120. The insulating film 140 is coated on the outside of the electrode assembly 120 and is located in the shell 110. The shell 110 includes a shell 111 and an end cover 112. The end cover 112 forms a first wall 113, and a pressure relief mechanism 115 is provided on the end cover 112. The electrode assembly 120 is provided in the shell 110 and is located on the bottom side of the end cover 112. The circumferential side wall 1111 of the shell 111 is provided around the outside of the electrode assembly 120. The electrode assembly 120 includes a positive electrode 121, a negative electrode 122 and a separator 124. The separator 124 is disposed between the negative electrode 122 and the positive electrode 121. The separator 124 is used to electrically insulate the adjacent negative electrodes 122 and the negative electrodes 122 and to transmit ions between the adjacent positive electrodes 121 and the negative electrodes 122. The electrode assembly 120 is provided with a first discharge channel 161 on one side along the first direction X (width direction) and a second discharge channel 162 on one side along the second direction Y (thickness direction). The inner wall surface of the circumferential side wall 1111 is coated with a thermal expansion material 151 to form a thermal expansion portion 150, wherein, as Figure 6 and Figure 7 As shown, the heat expansion material 151 on the inner wall surface of the circumferential side wall 1111 can be arranged in a circle, such as Fig.11 As shown, the circumferential side wall 1111 may also be provided with a heat expansion material 151 only on the inner wall surface of the first wall 113 of the straight portion 1203 corresponding to the electrode assembly 120. The heat expansion material 151 includes calcium gluconate. When the heat expansion part 150 is expanded, the electrode assembly 120 and the circumferential side wall 1111 are pressed against each other along the second direction Y. When the temperature is less than the preset temperature, the sum of the gap size between the electrode assembly 120 and the insulating film 140 and the gap size between the insulating film 140 and the circumferential side wall 1111 along the second direction Y is H. When the temperature is greater than or equal to the preset temperature, the total expansion size of the electrode assembly 120, the insulating film 140 and the heat expansion part 150 along the second direction Y is greater than H, so that the heat expansion part 150 is set to expand when the temperature is greater than or equal to the preset temperature, so that the electrode assembly 120 and the circumferential side wall 1111 are pressed against each other along the thickness direction. Wherein, the preset temperature is set to 80°C.

[0202] like Figure 3 As shown, combined with Figure 8 , Fig. 9 and Fig.12As shown, this embodiment provides a battery cell 100, which is different from the battery cell 100 of the previous embodiment in that the surface of the insulating film 140 is coated with a thermal expansion material to form a thermal expansion coating, i.e., a thermal expansion portion 150. The thermal expansion material is coated on at least one surface of the insulating film 140, such as the inner or outer surface or the inner and outer surfaces at the same time, or the thermal expansion material can be built into the film body of the insulating film 140. Figure 8 and Fig. 9 As shown, the insulating film 140 may be provided with a circle of thermal expansion portions 150 along the circumferential direction. Fig.12 As shown, the insulation film 140 may be provided with the thermal expansion portion 150 only in a region corresponding to the straight portion 1203 of the electrode assembly 120 .

[0203] like Figure 3 and Fig.10 As shown, this embodiment provides a battery cell 100, which is configured such that the large surface of the outer side surface of the electrode assembly 120 (which can be understood by referring to the first side surface 1201) is coated with a thermal expansion material to form a thermal expansion coating, i.e., a thermal expansion portion 150. The thermal expansion portion 150 is configured such that the large surface of the electrode assembly 120 faces the side of the circumferential side wall 1111 (the side of the first wall 113), and can also be configured such that the large surface of the electrode assembly 120 faces the side of the inside of the electrode assembly 120.

[0204] like Figure 3 , and combined with Fig.15 As shown, this embodiment provides a battery cell 100. The basic structure of the battery cell 100 of this embodiment is the same as that of the previous embodiment. The difference from the previous embodiment is that a heat expansion material 151 is coated on the isolation film 124 to form a heat expansion portion 150, wherein all surfaces of the two layers of isolation films 124 of the electrode assembly 120 (along the stacking direction, the isolation film 124 is arranged between the positive electrode 121 and the negative electrode 122, and the isolation film 124 is arranged between the negative electrode 122 and the positive electrode 121, so it can be two layers of isolation films 124) , any surface of the two layers of isolation films 124, both surfaces of one of the two isolation films 124, or a single surface can be coated with the heat expansion material 151 to form a heat expansion coating, i.e., the heat expansion portion 150, and the heat expansion portion 150 can face one or both of the positive electrode 121 and the negative electrode 122.

[0205] The embodiment of the present application further provides a battery device 10 , which includes a plurality of battery cells 100 proposed in the present application or any embodiment of the present application.

[0206] The battery device 10 of this embodiment has the same beneficial effects as the battery cell 100 proposed in this application or any embodiment of this application.

[0207] An embodiment of the present application also provides an electrical device, which includes the battery cell 100 proposed in the present application or any embodiment of the present application, or the battery device 10 proposed in the present application or any embodiment of the present application, and the battery cell 100 or the battery device 10 is used to store or provide electrical energy.

[0208] The electric device of this embodiment has the same beneficial effects as the battery cell 100 proposed in this application or any embodiment of this application.

[0209] The above description of each embodiment tends to emphasize the differences between the embodiments, and the same or similar aspects can be referenced to each other. For the sake of brevity, this article will not repeat them. If there is no special explanation, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0210] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; 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, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A battery cell, characterized in that: include: A housing having a first wall and a circumferential side wall connected to the first wall, wherein the first wall is provided with a pressure relief mechanism; An electrode assembly is arranged in the housing, wherein the first wall is located at one end of the electrode assembly, the circumferential side wall surrounds the outside of the electrode assembly, the electrode assembly includes a positive electrode, a negative electrode and a separator, the separator is arranged between the negative electrode and the positive electrode, the separator is used to electrically insulate the adjacent positive electrode from the negative electrode and transmit ions between the adjacent positive electrode and the negative electrode, the positive electrode is provided with a thermal expansion portion, and / or the negative electrode is provided with a thermal expansion portion, and / or the separator is provided with a thermal expansion portion, and / or the positive electrode and the separator are provided with a thermal expansion portion, and / or the negative electrode and the separator are provided with a thermal expansion portion, and / or the negative electrode and the separator are provided with a thermal expansion portion; Furthermore, a thermal expansion portion is provided on the inner wall surface of the circumferential side wall, and / or a thermal expansion portion is provided in the wall body of the circumferential side wall, and / or a thermal expansion portion is provided between the circumferential side wall and the electrode assembly; The thermal expansion portion is configured to expand at a temperature greater than or equal to a preset temperature, so that the electrode assembly and the circumferential side wall are pressed against each other.

2. The battery cell according to claim 1, characterized in that: A discharge channel is provided between the circumferential side wall and the electrode assembly, and the thermal expansion portion is configured to avoid at least a portion of the discharge channel.

3. The battery cell according to claim 2, characterized in that: The discharge channel includes a first discharge channel, and the first discharge channel is arranged on one side of the electrode assembly along the first direction. When the thermal expansion part is expanded, the electrode assembly and the circumferential side wall are pressed against each other along the second direction. The first direction intersects with the second direction, and the first direction and the second direction both intersect with the arrangement direction of the first wall and the electrode assembly.

4. The battery cell according to claim 3, characterized in that: The electrode assembly includes a straight portion and a curved portion, the circumferential side wall includes a first side wall arranged opposite to the straight portion and a second side wall arranged opposite to the curved portion, the first discharge channel is arranged between the curved portion and the second side wall, the thermal expansion portion is arranged on the first side wall, and / or the thermal expansion portion is arranged between the first side wall and the straight portion, and / or the thermal expansion portion is arranged on the straight portion.

5. The battery cell according to claim 3, characterized in that: The electrode assembly includes a first side surface and a second side surface, the area of ​​the first side surface is larger than that of the second side surface, the circumferential side wall includes a first side wall and a second side wall, the first side wall and the first side surface are arranged opposite to each other, the second side wall and the second side surface are arranged opposite to each other, the first exhaust channel is arranged between the second side surface and the second side wall, the first side wall is provided with the thermal expansion portion, and / or the thermal expansion portion is provided between the first side wall and the first side surface, and / or the thermal expansion portion is provided on the first side surface, and / or the thermal expansion portion is provided in the electrode assembly.

6. The battery cell according to claim 1, characterized in that: The battery cell also includes an insulating film, which is coated on the outside of the electrode assembly and located in the outer shell, and at least a portion of the insulating film located between the electrode assembly and the circumferential side wall is configured as the thermal expansion portion and / or the surface of at least a portion of the insulating film located between the electrode assembly and the circumferential side wall is configured with the thermal expansion portion.

7. The battery cell according to claim 6, characterized in that: At least a portion of the insulating film located between the electrode assembly and the circumferential side wall is configured as a composite film structure having a thermal expansion substance, and the composite film structure forms the thermal expansion portion.

8. The battery cell according to claim 7, characterized in that: The insulating film is located in at least a portion of the film body between the electrode assembly and the circumferential side wall and is provided with a accommodating cavity, the accommodating cavity is provided with the thermal expansion material to form the thermal expansion part, and the position corresponding to the insulating film and the thermal expansion part is configured to be able to extend, expand or rupture under the action of the expansion of the thermal expansion part.

9. The battery cell according to claim 1, characterized in that: At least a portion of at least one of the positive electrode, the negative electrode, and the separator is a composite structure having a thermal expansion substance, and the composite structure forms the thermal expansion portion.

10. The battery cell according to claim 1, characterized in that: The thermal expansion portion is provided on at least one of a surface of the positive electrode, a surface of the negative electrode, and a surface of the separator.

11. The battery cell according to any one of claims 1 to 10, characterized in that: The battery cell further includes an insulating film, which is coated on the outside of the electrode assembly and is located inside the housing; The thermal expansion portion is formed on the circumferential side wall by coating, and / or the thermal expansion portion is formed on the insulating film by coating, and / or the thermal expansion portion is formed on the electrode assembly by coating.

12. The battery cell according to any one of claims 1 to 10, characterized in that: The material of the heat expansion part includes a binder and a heat expansion substance.

13. The battery cell according to any one of claims 1 to 10, characterized in that: The heat expansion part comprises a flexible sleeve and a heat expansion material, and the flexible sleeve is coated on the outside of the heat expansion material.

14. The battery cell according to any one of claims 1 to 10, characterized in that: The heat expansion portion includes a heat expansion material, and the heat expansion material includes calcium gluconate; And / or, the preset temperature ranges from 80°C to 130°C.

15. The battery cell according to any one of claims 1 to 10, characterized in that: The preset temperature is 80°C.

16. The battery cell according to any one of claims 1 to 10, characterized in that: The battery cell further includes an insulating film, which is coated on the outside of the electrode assembly and is located inside the housing; When the thermal expansion portion expands, the electrode assembly and the circumferential side wall are pressed against each other along the second direction. When the temperature is lower than the preset temperature, the sum of the gap size between the electrode assembly and the insulating film and the gap size between the insulating film and the circumferential side wall along the second direction is H. When the temperature is greater than or equal to the preset temperature, the total expansion size of the electrode assembly, the insulating film and the thermal expansion portion along the second direction is greater than H, and the second direction intersects with the arrangement direction of the first wall and the electrode assembly.

17. A battery device, characterized in that: The invention comprises a plurality of battery cells according to any one of claims 1 to 16.

18. An electrical equipment, characterized in that: The electrical equipment comprises the battery cell according to any one of claims 1 to 16, or the electrical equipment comprises the battery device according to claim 17, and the battery cell is used to store or provide electrical energy.

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