Battery cell, battery, electric device, and method for manufacturing battery cell

Abstract

The application relates to a battery monomer, a battery, a power utilization device and a method for preparing a battery monomer. The battery monomer comprises: an electrode assembly, the electrode assembly can be switched from a first mode to a second mode, the volume of the electrode assembly in the first mode is smaller than the volume in the second mode; a shell for accommodating the electrode assembly; a cover assembly for closing an open opening of the shell; wherein the shell comprises a side wall part and a bottom wall part connected with the side wall part, at least one of the side wall part and the bottom wall part is provided with a recess recessed in a direction away from the electrode assembly on one side of the electrode assembly, and the electrode assembly partially extends into an inner cavity of the recess in the second mode. The battery monomer provided by the application has a higher energy density and is more optimized in performance.

Description

Technical Field

[0001] This application relates to the field of energy storage technology, and in particular to a battery cell, a battery, an electrical device, and a method for preparing a battery cell. Background Technology

[0002] Batteries are widely used in electronic devices such as mobile phones, laptops, electric vehicles, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and power tools, etc.

[0003] In the development of battery technology, besides improving the safety performance of individual battery cells, energy density is also a crucial consideration. Therefore, how to improve the energy density of individual battery cells is a pressing issue that needs to be addressed in battery technology. Summary of the Invention

[0004] This application provides a battery cell, a battery, an electrical device, and a method for preparing a battery cell. The battery cell has a high energy density and optimizes the performance of the battery cell.

[0005] On one hand, according to an embodiment of this application, a battery cell is provided, including: an electrode assembly, which can be switched from a first form to a second form, the volume of the electrode assembly in the first form being smaller than the volume in the second form; a housing for accommodating the electrode assembly; and a cover assembly for closing the open opening of the housing; wherein the housing includes a side wall portion and a bottom wall portion connected to the side wall portion, at least one of the side wall portion and the bottom wall portion having a recessed portion recessed in a direction away from the electrode assembly on the side facing the electrode assembly, and the electrode assembly partially extending into the inner cavity of the recess in the second form.

[0006] In the above technical solution, the housing includes a sidewall portion and a bottom wall portion connected to the sidewall portion. At least one of the sidewall portion and the bottom wall portion has a recessed portion on the side facing the electrode assembly, which is recessed away from the electrode assembly, allowing the electrode assembly to partially extend into the cavity of the recess in the second configuration. In other words, by providing a recess on the sidewall or bottom wall portion of the housing to increase the volume of the housing for accommodating the electrode assembly, when the electrode assembly expands from the first configuration to the second configuration, the increased volume can extend into the cavity of the recess. Without reducing the volume of the electrode assembly, the recess formed on the housing can absorb the deformation of the electrode assembly, ensuring both the safety performance of the battery cell during operation and maintaining the energy density of the battery cell, thus optimizing the performance of the battery cell.

[0007] According to one aspect of the embodiments of this application, the minimum distance between the electrode assembly and the bottom wall of the recess in the second configuration is less than the minimum distance between the electrode assembly and the bottom wall of the recess in the first configuration.

[0008] In the above technical solution, the electrode assembly can be located within the cavity of the recess in the first configuration, or it can be located outside the cavity of the recess. In the second configuration, it partially extends into the cavity of the recess. When the electrode assembly is in the second configuration, the portion of the electrode assembly extending into the cavity of the recess ensures the deformation requirements of the electrode assembly while allowing the recess to accommodate the increased volume of the electrode assembly after deformation. This allows the electrode assembly to adapt to deformation without reducing its volume, thus ensuring the safety performance and energy density of the battery cell.

[0009] According to one aspect of the embodiments of this application, the recess is formed by removing a portion of the housing by a predetermined depth through the inner surface of the housing.

[0010] The above configuration ensures the accommodating requirements of the electrode assembly in the second configuration, facilitates the formation of the recess, and meets the requirement of increased internal accommodating space.

[0011] According to one aspect of the embodiments of this application, the sidewall portion includes two first sidewall portions and two second sidewall portions, the two first sidewall portions are spaced apart and disposed opposite to each other, the two second sidewall portions are spaced apart and disposed opposite to each other, each second sidewall portion is connected to the two first sidewall portions respectively, and at least one first sidewall portion or at least one second sidewall portion is provided with a recess.

[0012] With the above-described design, when the electrode assembly, whether of a wound or stacked structure, expands, at least a portion of the electrode assembly can extend into the recess, ensuring the deformation requirements of the electrode assembly and guaranteeing the safety performance of the battery cell during operation. Simultaneously, it eliminates the need to reduce the volume of the battery cell to accommodate its deformation, thereby increasing the energy density of the battery cell.

[0013] According to one aspect of the embodiments of this application, each of the first sidewall portions is provided with a recess, and / or each of the second sidewall portions is provided with a recess.

[0014] By providing recesses on both first sidewalls, the space of the housing in the arrangement direction of the two first sidewalls is effectively increased. When the electrode assembly deforms in the second configuration and in the arrangement direction of the two first sidewalls, the recesses on the two first sidewalls can accommodate the increased volume of the electrode assembly due to expansion. This not only ensures the safety performance of the battery cell but also further improves the energy density of the battery cell.

[0015] By providing recesses on both second sidewalls, the space of the housing in the arrangement direction of the two second sidewalls is effectively increased. This allows the energy density of the battery cell to be increased by accommodating the expanded volume of the electrode assembly when the electrode assembly deforms in the second configuration and in the arrangement direction of the two second sidewalls.

[0016] According to one aspect of the embodiments of this application, the electrode assembly is a wound structure, the electrode assembly includes a straight portion and an arc-shaped bending portion, the arc-shaped bending portion has a top region disposed opposite to the straight portion, a first sidewall portion faces the top region and is provided with a recess, the orthographic projection of the top region on the first sidewall portion is located on the bottom wall of the recess, so that in a second form, the top region is located in the inner cavity of the recess.

[0017] During the deformation process of the electrode assembly, the top region of its arc-shaped bend will expand. By providing a recess with the first sidewall facing the top region, the orthographic projection of the top region on the first sidewall is located on the bottom wall of the recess. In the second form, the top region is located in the inner cavity of the recess. This allows the step formed by the sidewall of the recess and the surface of the housing facing the electrode assembly to avoid the top region of the arc-shaped bend, preventing interference of the electrode assembly at the step after the electrode assembly expands, thus preventing lithium plating problems from occurring in the electrode assembly.

[0018] According to one aspect of the embodiments of this application, the bottom wall of the recess is provided with a groove, which is configured to crack when the pressure of the gas inside the housing reaches a threshold, so as to discharge the gas to the outside of the housing.

[0019] By incorporating scoring grooves, when the internal pressure of the casing reaches a threshold, the casing can tear at the scoring grooves, releasing the gas inside and preventing excessive pressure from causing the casing to burst, thus improving the safety performance of the battery cell. Furthermore, since the scoring grooves are located on the bottom wall of the recess, which is formed by at least one of the sidewall and bottom wall portions having a recessed section facing away from the electrode assembly, the thickness of the bottom wall of the recess is less than the thickness of the walls in other areas of the casing. When the internal pressure of the battery cell becomes too high, the weaker areas will crack pre-crack. Therefore, placing the scoring grooves on the bottom wall of the recess facilitates tearing of the scoring grooves when the internal pressure reaches a threshold, ensuring the safety performance of the battery cell.

[0020] Furthermore, since the recess is located on the bottom or side wall of the housing, when the battery cell is inverted and the cover assembly is facing down, such as when a car is in motion, the groove is less likely to be scratched, thus preventing damage and ensuring the lifespan of the battery cell.

[0021] According to one aspect of the embodiments of this application, the groove is formed by the bottom wall of the recess facing the inner surface of the electrode assembly and recessing in a direction away from the electrode assembly; or, the groove is formed by the bottom wall of the recess facing away from the outer surface of the electrode assembly and recessing in a direction closer to the electrode assembly.

[0022] According to one aspect of the embodiments of this application, the groove includes a first groove that extends along a straight line trajectory or an arc trajectory.

[0023] The groove adopts the above-mentioned structure, which is conducive to molding and allows the casing to crack at the first groove when the internal pressure exceeds the threshold, which facilitates the release of gas and ensures the safety of the battery cell.

[0024] According to one aspect of the embodiments of this application, the groove further includes a second groove that extends along a straight trajectory, and the first groove and the second groove are intersecting.

[0025] By setting a second groove, when the pressure inside the casing exceeds a threshold, the casing can be torn open at both the first and second grooves to release the gas inside, thus ensuring the safety performance of the battery cell.

[0026] According to one aspect of the embodiments of this application, both the first groove and the second groove extend along a straight trajectory, the extension direction of the first groove is perpendicular to the extension direction of the second groove, and the first groove and the second groove together form a "T" shaped pattern or a "+" shaped pattern.

[0027] According to one aspect of the embodiments of this application, the groove further includes a third groove and a fourth groove, the third groove and the fourth groove being spaced apart and relatively distributed, and the third groove and the fourth groove being intersected with the first groove respectively.

[0028] With the above settings, when the pressure inside the casing exceeds the threshold, it can be torn open at the first, third, and fourth grooves to release the gas inside the casing and ensure the safety performance of the battery cell.

[0029] According to one aspect of the embodiments of this application, the third groove and the fourth groove both extend along a straight trajectory. The third groove is disposed at one end of the first groove in its own extension direction and is connected to the first groove. The fourth groove is disposed at the other end of the first groove in its extension direction and is connected to the first groove. The first groove, the third groove and the fourth groove together form a "U" shaped pattern.

[0030] According to one aspect of the embodiments of this application, the groove includes a pair of groove units arranged in a symmetrical and spaced apart. Each groove unit includes a fifth groove and a sixth groove. One end of the fifth groove intersects with one end of the sixth groove. In the pair of groove units, the fifth groove of one unit is spaced apart from the fifth groove of the other unit and extends toward each other. The sixth groove of one unit is spaced apart from the sixth groove of the other unit and extends in the same direction.

[0031] With the above settings, when the internal pressure of the casing exceeds the threshold, it can tear open at the fifth and sixth grooves of each grooved unit to release the gas inside the casing and ensure the safety performance of the battery cell.

[0032] In another aspect, an embodiment of this application provides a battery, which includes the aforementioned battery cell.

[0033] In another aspect, an electrical device is provided according to an embodiment of this application, wherein the battery described above is included, and the battery is used to provide electrical energy.

[0034] In another aspect, according to embodiments of this application, a method for preparing a battery cell is provided, comprising:

[0035] An electrode assembly is provided, which can be switched from a first form to a second form, and the volume of the electrode assembly in the first form is smaller than the volume in the second form.

[0036] A housing is provided, and an electrode assembly is inserted into the housing through an opening in the housing. The housing includes a side wall portion and a bottom wall portion connected to the side wall portion. At least one of the side wall portion and the bottom wall portion has a recessed portion on the side facing the electrode assembly, which is recessed away from the electrode assembly. In a second configuration, the electrode assembly partially extends into the cavity of the recess.

[0037] Provide a cover assembly to seal the opening.

[0038] In another aspect, according to embodiments of this application, an apparatus for preparing a battery cell is provided, comprising: a first assembly device configured to provide an electrode assembly, the electrode assembly being switchable from a first form to a second form, the volume of the electrode assembly in the first form being smaller than the volume in the second form; a second assembly device configured to provide a housing, wherein the electrode assembly is inserted into the housing through an opening in the housing, the housing including a side wall portion and a bottom wall portion connected to the side wall portion, at least one of the side wall portion and the bottom wall portion having a recessed portion recessed in a direction away from the electrode assembly on the side facing the electrode assembly, the electrode assembly partially extending into the cavity of the recess in the second form; and a third assembly device configured to provide a cover assembly, thereby sealing the opening with the cover assembly.

[0039] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0040] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0041] Figure 1 This application provides structural schematic diagrams of vehicles for some embodiments;

[0042] Figure 2 This application provides schematic diagrams of the battery structure for some embodiments.

[0043] Figure 3 An exploded view of a battery cell provided in some embodiments of this application;

[0044] Figure 4 A front view of a battery cell provided in some embodiments of this application;

[0045] Figure 5 for Figure 4 A cross-sectional view along the AA direction;

[0046] Figure 6 for Figure 5 Enlarged view at point B in the middle;

[0047] Figure 7 A partial enlarged view of a battery cell provided for other embodiments of this application;

[0048] Figure 8 A partial enlarged view of a battery cell provided for some embodiments of this application;

[0049] Figure 9 This is a side view of a battery cell according to some embodiments of this application;

[0050] Figure 10 for Figure 9 A cross-sectional view along the CC direction;

[0051] Figure 11 This is an isometric view of a battery cell according to some embodiments of this application;

[0052] Figure 12 This is an isometric view of a battery cell according to some embodiments of this application;

[0053] Figure 13 This is an isometric view of a battery cell according to some embodiments of this application;

[0054] Figure 14 This is an isometric view of a battery cell according to some embodiments of this application;

[0055] Figure 15 This is a flowchart illustrating a method for preparing a battery cell according to some embodiments of this application.

[0056] 1000 - Vehicles;

[0057] 100 - Battery; 200 - Controller; 300 - Motor;

[0058] 10-Box body; 11-First part; 12-Second part;

[0059] 20-cell battery;

[0060] 21-Shell;

[0061] 211-Side wall portion; 2111-First side wall portion; 2112-Second side wall portion;

[0062] 212 - Bottom wall portion;

[0063] 213 - Recess; 2131 - Bottom wall; 2132 - Side wall;

[0064] 214 - Scratching groove; 2141 - First groove; 2142 - Second groove; 2143 - Third groove; 2144 - Fourth groove; 2145 - Groove unit; 2145a - Fifth groove; 2145b - Sixth groove;

[0065] 22-Electrode assembly; 22a-Positive electrode tab; 22b-Negative electrode tab; 221-Straight section; 222-Curved bend section; 2221-Top region;

[0066] 23-Cover assembly; 231-Positive electrode terminal; 232-Negative electrode terminal.

[0067] In the accompanying drawings, the same parts use the same reference numerals. The drawings are not drawn to scale. Detailed Implementation

[0068] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0069] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0070] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0071] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0072] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0073] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0074] In this application, "multiple" means two or more (including two).

[0075] In this application, the battery cell may include lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries, or magnesium-ion batteries, etc., and the embodiments of this application are not limited to these. The battery cell may be cylindrical, flat, cuboid, or other shapes, etc., and the embodiments of this application are not limited to these. Battery cells are generally divided into three types according to their packaging method: cylindrical battery cells, square battery cells, and pouch battery cells, and the embodiments of this application are not limited to these.

[0076] The battery mentioned in the embodiments of this application refers to a single physical module comprising one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in this application may include a battery module or a battery pack. A battery generally includes a housing for encapsulating one or more battery cells. The housing prevents liquids or other foreign matter from affecting the charging or discharging of the battery cells.

[0077] A battery cell includes an electrode assembly, which consists of a positive electrode, a negative electrode, and a separator. The battery cell primarily functions by the movement of metal ions between the positive and negative electrodes. The positive electrode includes a positive current collector and a positive active material layer. The positive active material layer is coated on the surface of the positive current collector, and the uncoated positive current collector protrudes beyond the coated one, serving as the positive electrode tab. Taking a lithium-ion battery as an example, the positive current collector can be made of aluminum, and the positive active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The negative electrode includes a negative current collector and a negative active material layer. The negative active material layer is coated on the surface of the negative current collector, and the uncoated negative current collector protrudes beyond the coated one, serving as the negative electrode tab. The negative electrode current collector can be made of copper, and the negative electrode active material can be carbon or silicon, etc. To ensure that a large current can pass through without melting, there are multiple positive electrode tabs stacked together, and there are multiple negative electrode tabs stacked together. The separator can be made of PP (polypropylene) or PE (polyethylene), etc. In addition, the electrode assembly can be a wound structure or a stacked structure, and the embodiments of this application are not limited to these.

[0078] The development of battery technology must take into account multiple design factors, such as safety, cycle life, discharge capacity, charge / discharge rate and other performance parameters. In addition, the energy density of the battery also needs to be considered.

[0079] When a battery cell is working, its electrode assembly expands. To ensure the safety of the electrode assembly, its volume is usually reduced and spaced apart from the inside of the casing. This allows the electrode assembly to expand and deform during operation without breaking the casing and causing it to explode, thus ensuring its safety.

[0080] The inventors discovered that while reducing the size of the electrode assembly can ensure the safety of the battery cell during operation, it also has corresponding drawbacks. The main issue is that the reduction in the size of the electrode assembly will lead to a decrease in the energy density of the battery cell, thus affecting the performance of the battery cell.

[0081] Therefore, embodiments of this application provide a battery cell whose electrode assembly can be switched from a first form to a second form, with the volume of the electrode assembly in the first form being smaller than that in the second form. At least one of the side wall portion and the bottom wall portion of the housing has a recessed portion that is recessed away from the electrode assembly on the side facing the electrode assembly, and the electrode assembly in the second form partially extends into the cavity of the recessed portion. By providing a recessed portion that is recessed away from the electrode assembly on at least one of the side wall portion and the bottom wall portion of the housing on the side facing the electrode assembly, the internal accommodating space of the housing can be increased. Without reducing the volume of the electrode assembly, the deformation of the electrode assembly can be absorbed by the recessed portion formed on the housing, thus ensuring both the safety performance of the battery cell during operation and maintaining the energy density of the battery cell, thereby optimizing the performance of the battery cell.

[0082] The battery cells described in the embodiments of this application are applicable to batteries and electrical devices and equipment that use batteries.

[0083] Electrical devices and equipment can include vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools, etc. Vehicles can be gasoline-powered cars, natural gas-powered cars, or new energy vehicles; new energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This application does not impose special limitations on the above-mentioned electrical equipment.

[0084] For ease of explanation, the following embodiments will use a vehicle as an example of an electrical device.

[0085] Please refer to Figure 1 , Figure 1 The diagram below illustrates the structure of a vehicle 1000 according to some embodiments of this application. A battery 100 is disposed inside the vehicle 1000, and the battery 100 may be located at the bottom, front, or rear of the vehicle 1000. The battery 100 can be used to power the vehicle 1000; for example, the battery 100 can serve as the operating power source for the vehicle 1000.

[0086] The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to supply power to the motor 300, for example, for the power needs of the vehicle 1000 during startup, navigation and driving.

[0087] In some embodiments of this application, the battery 100 can not only serve as the operating power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0088] Please refer to Figure 2 , Figure 2 The present invention provides a schematic diagram of the structure of a battery 100 according to some embodiments. The battery 100 includes a housing 10 and a battery cell 20. The housing 10 is used to house the battery cell 20.

[0089] The housing 10 is a component that houses the battery cell 20, providing a space for the battery cell 20. The housing 10 can adopt various structures. In some embodiments, the housing 10 may include a first part 11 and a second part 12, which overlap each other to define a space for accommodating the battery cell 20. The first part 11 and the second part 12 can have various shapes, such as a cuboid or a cylinder. The first part 11 can be a hollow structure open on one side, and the second part 12 can also be a hollow structure open on one side, with the open side of the second part 12 overlapping the open side of the first part 11, thus forming a housing 10 with a accommodating space. Alternatively, the first part 11 can be a hollow structure open on one side, and the second part 12 can be a plate-like structure, with the second part 12 overlapping the open side of the first part 11, thus forming a housing 10 with a accommodating space. The first part 11 and the second part 12 can be sealed using a sealing element, such as a sealing ring or sealant.

[0090] In battery 100, there can be one or more battery cells 20. If there are multiple battery cells 20, they can be connected in series, parallel, or in a mixed manner. A mixed connection means that multiple battery cells 20 are connected in both series and parallel. Alternatively, multiple battery cells 20 can be first connected in series, parallel, or in a mixed manner to form a battery module, and then multiple battery modules can be connected in series, parallel, or in a mixed manner to form a whole, which is then housed within the housing 10. Another option is that all battery cells 20 can be directly connected in series, parallel, or in a mixed manner, and then the whole consisting of all battery cells 20 is housed within the housing 10.

[0091] Please refer to Figures 3 to 6 As shown, Figure 3 This is an exploded view of a battery cell 20 provided in some embodiments of this application. Figure 4 This is a front view of a battery cell 20 provided in some embodiments of this application. Figure 5 For along Figure 4 Sectional view along the AA direction. Figure 6 for Figure 5 Enlarged view of section B in the middle.

[0092] The battery cell 20 includes a housing 21, an electrode assembly 22, and a cover assembly 23. The housing 21 is used to house the electrode assembly 22, which can be switched from a first form to a second form. The volume of the electrode assembly 22 in the first form is smaller than that in the second form. The cover assembly 23 is used to close the open opening of the housing 21. The housing 21 includes a side wall portion 211 and a bottom wall portion 212 connected to the side wall portion 211. At least one of the side wall portion 211 and the bottom wall portion 212 has a recess 213 on the side facing the electrode assembly 22, which is recessed away from the electrode assembly 22. In the second form, the electrode assembly 22 partially extends into the cavity of the recess 213.

[0093] The housing 21 is a component used to house the electrode assembly 22. The housing 21 can be a hollow structure with an opening at one end. The housing 21 can be of various shapes, such as a cylinder or a cuboid. The housing 21 can be made of various materials, such as copper, iron, aluminum, steel, or aluminum alloy.

[0094] The portion of housing 21 that is disposed opposite to cover assembly 23 may be its bottom wall portion 212, and the portion of housing 21 that connects the bottom wall portion 212 and cover assembly 23 may be the side wall portion 211 of housing 21.

[0095] A recess 213 may be provided on the side wall portion 211 of the housing 21, or on the bottom wall portion 212 of the housing 21. Alternatively, a recess 213 may be provided on both the side wall portion 211 and the bottom wall portion 212 of the housing 21.

[0096] The recess 213 may be recessed into the side of the inner wall surface facing the electrode assembly 22, away from the electrode assembly 22, formed by the side wall portion 211 and / or the bottom wall portion 212. The thickness of the bottom wall 2131 of the recess 213 is less than the wall thickness of the housing 21.

[0097] The electrode assembly 22 within the housing 21 can be one or more. For example, such as Figure 3 As shown, there are multiple electrode assemblies 22, which are stacked in layers.

[0098] Electrode assembly 22 is the component in the battery cell 20 where the electrochemical reaction takes place. Electrode assembly 22 may include a positive electrode, a negative electrode, and a separator. Electrode assembly 22 can be a wound structure formed by winding the positive electrode, separator, and negative electrode, or a stacked structure formed by arranging the positive electrode, separator, and negative electrode in layers.

[0099] The positive electrode may include a positive current collector and positive active material layers coated on opposite sides of the positive current collector. The negative electrode may include a negative current collector and negative active material layers coated on opposite sides of the negative current collector. The electrode assembly 22 has a positive electrode tab 22a and a negative electrode tab 22b. The positive electrode tab 22a may be a portion of the positive electrode that is not coated with a positive active material layer, and the negative electrode tab 22b may be a portion of the negative electrode that is not coated with a negative active material layer.

[0100] The electrode assembly 22 can be in the form of the battery cell 20 in a state where it has not expanded. The electrode assembly 22 can be in the form of the battery cell 20 in an operating state and when it has expanded.

[0101] The volume of electrode assembly 22 is the volume of its outer contour. For example, if its outer contour is a square, then the volume is the product of its length, width, and height, which can be determined according to the structural form of electrode assembly 22.

[0102] The cover assembly 23 is a component that closes the opening of the housing 21 to isolate the internal environment of the battery cell 20 from the external environment. The cover assembly 23 and the housing 21 together define a sealed space for accommodating the electrode assembly 22, electrolyte, and other components.

[0103] The shape of the cover assembly 23 can be adapted to the shape of the housing 21. For example, if the housing 21 is a cuboid structure, the cover assembly 23 can be a rectangular plate structure adapted to the housing 21. Alternatively, if the housing 21 is a cylindrical structure, the cover assembly 23 can be a circular plate structure adapted to the housing 21. The end cap can also be made of various materials, such as copper, iron, aluminum, steel, or aluminum alloy. The material of the end cap can be the same as or different from the material of the housing 21.

[0104] Electrode terminals can be provided on the cover assembly 23. These terminals are used for electrical connection with the electrode assembly 22 to output electrical energy from the battery cell 20. The electrode terminals may include a positive electrode terminal 231 and a negative electrode terminal 232. The positive electrode terminal 231 is used for electrical connection with the positive electrode tab 22a, and the negative electrode terminal 232 is used for electrical connection with the negative electrode tab 22b. The positive electrode terminal 231 and the positive electrode tab 22a can be directly or indirectly connected, as can the negative electrode terminal 232 and the negative electrode tab 22b.

[0105] The battery cell 20 provided in this application embodiment has a housing 21 including a side wall portion 211 and a bottom wall portion 212 connected to the side wall portion 211. At least one of the side wall portion 211 and the bottom wall portion 212 has a recess 213 recessed in a direction away from the electrode assembly 22 on the side facing the electrode assembly 22, so that the electrode assembly 22 partially extends into the inner cavity of the recess 213 in a second configuration. That is, by providing the recess 213 on the side wall portion 211 and / or the bottom wall portion 212 of the housing 21 to increase the volume of the housing 21 for accommodating the electrode assembly 22, when the electrode assembly 22 expands and switches from the first configuration to the second configuration, the increased volume of the expanded portion can extend into the inner cavity of the recess 213. Without reducing the volume of the electrode assembly 22, the deformation of the electrode assembly 22 can be absorbed by the recess 213 formed on the housing 21, which can ensure the safety performance of the battery cell 20 during operation, and at the same time ensure the energy density of the battery cell 20, thus optimizing the performance of the battery cell 20.

[0106] In some embodiments, the minimum distance between the electrode assembly 22 and the bottom wall 2131 of the recess 213 in the second configuration is less than the minimum distance between the electrode assembly 22 and the bottom wall 2131 of the recess 213 in the first configuration.

[0107] The recess 213 includes a bottom wall 2131 and a side wall 2132. The bottom wall 2131 is disposed facing the electrode assembly 22, and the side wall 2132 is disposed intersecting with the bottom wall 2131. The bottom wall 2131 and the side wall 2132 of the recess 213 together enclose the inner cavity of the recess.

[0108] The minimum distance between the electrode assembly 22 and the bottom wall 2131 can be understood as the minimum vertical distance between the side surface of the electrode assembly 22 facing the recess 213 and the bottom wall 2131 of the recess 213.

[0109] With the above configuration, the electrode assembly 22 can be located within the cavity of the recess 213 in the first configuration, or it can be located outside the cavity of the recess 213, with a portion extending into the cavity of the recess 213 in the second configuration. When the electrode assembly 22 is in the second configuration, the portion of the electrode assembly 22 extending into the cavity of the recess 213 ensures that the deformation requirements of the electrode assembly 22 are met, while the recess 213 can accommodate the increased volume of the electrode assembly 22 after deformation. This allows the electrode assembly 22 to adapt to deformation without reducing its volume, thus ensuring the safety performance and energy density of the battery cell 20.

[0110] In some embodiments, the recess 213 is formed by removing a portion of the housing 21 by a predetermined depth through the inner surface of the housing 21.

[0111] Removing a portion of the housing 21 to a predetermined depth to form a recess 213 can be understood as forming the recess by removing a portion of the material from the flat bottom wall portion 212 and / or side wall portion 211 of the housing 21 through cutting or other methods.

[0112] The recess 213 adopts the above-described manner, which can not only ensure the accommodation requirements of the electrode assembly 22 in the second form, but also facilitate the formation of the recess 213 and ensure the increased accommodation space inside the housing 21.

[0113] In some embodiments, the sidewall portion 211 includes two first sidewall portions 2111 and two second sidewall portions 2112, the two first sidewall portions 2111 are spaced apart and disposed opposite to each other, the two second sidewall portions 2112 are spaced apart and disposed opposite to each other, each second sidewall portion 2112 is connected to the two first sidewall portions 2111 respectively, and at least one first sidewall portion 2111 or at least one second sidewall portion 2112 is provided with a recess 213.

[0114] The size of the first sidewall portion 2111 can be larger than the size of the second sidewall portion 2112, or it can be smaller than the size of the second sidewall portion 2112. The two first sidewall portions 2111 and the two second sidewall portions 2112 can be together to form a rectangle.

[0115] A recess 213 may be provided on one of the two first sidewall portions 2111, or a recess 213 may be provided on both first sidewall portions 2111.

[0116] A recess 213 may be provided on one of the two second sidewall portions 2112, or a recess 213 may be provided on both second sidewall portions 2112.

[0117] By providing a recess 213 in at least one first sidewall portion 2111 or at least one second sidewall portion 2112, when the electrode assembly 22, whether in a wound or stacked structure, expands, at least a portion of the electrode assembly 22 can extend into the recess 213, ensuring the deformation requirements of the electrode assembly 22 and guaranteeing the safety performance of the battery cell 20 during operation. Simultaneously, it eliminates the need to reduce the volume of the battery cell 20 to accommodate its deformation, thereby increasing the energy density of the battery cell 20.

[0118] In some embodiments, recesses 213 may be provided on both first sidewall portions 2111. The recesses 213 on the two first sidewall portions 2111 may have the same or different dimensions.

[0119] The number of recesses 213 on the first sidewall portion 2111 and the second sidewall portion 2112 can both be one, or they can both be two or more. The specific number can be determined based on the number of electrode assemblies 22 included in the battery cell 20 and the structural form of the electrode assemblies 22.

[0120] When the battery cell 20 is in operation, its electrode assembly 22 deforms in all directions as it expands. By providing recesses 213 on both first sidewall portions 2111, the space of the housing 21 in the arrangement direction of the two first sidewall portions 2111 is effectively increased. This allows the electrode assembly 22 to accommodate the increased volume of the electrode assembly 22 when it deforms in the second configuration and in the arrangement direction of the two first sidewall portions 2111. This ensures the safety performance of the battery cell 20 and further improves the energy density of the battery cell 20.

[0121] Please refer to Figure 7 , Figure 7 This is a partially enlarged view of a battery cell provided in some other embodiments of this application. In some embodiments, recesses 213 may be provided on both second sidewall portions 2112, and the dimensions of the recesses 213 on the two second sidewall portions 2112 may be the same or different.

[0122] By providing recesses 213 on both second sidewall portions 2112, the space of the housing 21 in the arrangement direction of the two second sidewall portions 2112 is effectively increased. This allows the electrode assembly 22 to accommodate the increased volume of the electrode assembly 22 when it deforms in the second configuration and in the arrangement direction of the two second sidewall portions 2112. This ensures the safety performance of the battery cell 20 and further improves the energy density of the battery cell 20.

[0123] Please refer to Figure 8 , Figure 8 This is a partial enlarged view of a battery cell provided in some embodiments of this application. In some embodiments, the battery cell 20 provided in this application has an electrode assembly 22 with a wound structure. The electrode assembly 22 includes a straight portion 221 and an arc-shaped bending portion 222. The arc-shaped bending portion 222 has a top region 2221 disposed opposite to the straight portion 221. A first sidewall portion 2111 faces the top region 2221 and is provided with a recess 213. The orthographic projection of the top region 2221 on the first sidewall portion 2111 is located on the bottom wall 2131 of the recess 213, so that in a second configuration, the top region 2221 is located in the inner cavity of the recess 213.

[0124] For a wound structure, during the winding process, it includes a straight section 221 in the middle and bent sections on both sides of the straight section 221. The bent sections can be arc-shaped and protrude in a direction away from the straight section 221.

[0125] The top region 2221 of the arc-shaped bend 222 can be understood as the region furthest from the straight portion 221 in vertical distance. Since the top region 2221 of the arc-shaped bend 222 will expand during the deformation of the electrode assembly 22, by providing a recess 213 with the first sidewall portion 2111 facing the top region 2221, the orthographic projection of the top region 2221 onto the first sidewall portion 2111 is located on the bottom wall 2131 of the recess 213. This ensures that in the second configuration, the top region 2221 of the electrode assembly 22 is located within the cavity of the recess 213. This allows the step formed by the sidewall of the recess 213 and the surface of the housing 21 facing the electrode assembly 22 to avoid the top region 2221 of the arc-shaped bend 222, preventing interference at the step after the electrode assembly 22 expands and thus avoiding lithium plating problems.

[0126] In some embodiments, recesses 213 may be provided on both first sidewall portions 2111. Since the electrode assembly 22 adopts a wound structure, arc-shaped bends 222 are provided on both sides of the straight portion 221. The recesses 213 provided on each first sidewall portion 2111 can accommodate the expansion and deformation of each arc-shaped bend 222, ensuring the safety performance and energy density of the battery cell 20.

[0127] When the electrode assembly 22 has a wound structure, it is not limited to providing recesses 213 only on the two first sidewall portions 2111, but also on the two second sidewall portions 2112. Since the flat portion 221 of the electrode assembly 22 of the battery cell 20 will also expand when it is working, that is, the expansion of the large surface area, by providing recesses 213 on the two second sidewall portions 2112, the expansion of the flat portion 221 of the electrode assembly 22 can be accommodated, thereby improving the safety performance and energy density of the battery cell 20.

[0128] It is understood that the winding structure of the electrode assembly 22 is only an optional implementation method, but is not limited to the above method. In some other embodiments, the electrode assembly 22 can also be a stacked structure. When it is a stacked structure, a recess 213 can also be provided on at least one first sidewall portion 2111 and / or at least one second sidewall portion 2112 to adapt to the deformation requirements of the electrode assembly 22 when switching to the second form.

[0129] It is understood that the battery cell 20 provided in the above embodiments is illustrated by setting the recess 213 in the side wall portion 211 as an example, which is an optional implementation. In some other embodiments, the bottom wall portion 212 of the housing 21 may also be provided with a recess 213, so that the end of the electrode assembly 22 facing away from the cover assembly 23 extends into the recess 213 on the bottom wall portion 212 of the housing 21. This can also increase the internal accommodating space of the housing 21, ensuring that the electrode assembly 22 has the expansion and deformation requirements when switching from the first form to the second form during operation of the battery cell 20, thus ensuring safety performance. At the same time, it can also ensure the energy density of the battery cell 20 and optimize the performance of the battery cell 20.

[0130] Within the battery cell 20, repeated charge-discharge cycles lead to side reactions that continuously generate gas, creating internal pressure. As this pressure increases, the gas between the electrodes cannot be expelled in time, affecting lithium-ion insertion and extraction, and consequently increasing the risk of lithium plating. To ensure the safety of the battery cell 20, a venting structure is typically incorporated to remove the gas generated within it, thus guaranteeing its safety.

[0131] In some embodiments, the bottom wall of the recess 213 of the battery cell 20 provided in this application embodiment is provided with a groove 214. The groove 214 is configured to crack when the pressure of the gas inside the housing 21 reaches a threshold, so as to discharge the gas to the outside of the housing 21.

[0132] Please refer to Figure 9 as well as Figure 10 , Figure 9 This is a side view of a battery cell according to some embodiments of this application. Figure 10 for Figure 9 A cross-sectional view along the CC direction. The groove 214 can be located on the bottom wall 2131 of the recess 213 facing the inner wall surface of the electrode assembly 22, or it can be located on the bottom wall 2131 of the recess 213 away from the outer wall surface of the electrode assembly 22. The depth of the groove 214 is less than the wall thickness of the bottom wall 2131 of the recess 213.

[0133] By providing the groove 214, when the pressure inside the casing 21 reaches a threshold, it can tear through the groove 214 to release the gas inside the casing 21, preventing the casing 21 from bursting due to excessive pressure and improving the safety performance of the battery cell 20. Furthermore, since the groove 214 is located on the bottom wall 2131 of the recess 213, which is formed by at least one of the side wall portion 211 and the bottom wall portion 212 being recessed away from the electrode assembly 22, the thickness of the bottom wall 2131 of the recess 213 is less than the thickness of the walls in other areas of the casing 21. When the pressure inside the battery cell 20 is too high, the weaker areas will crack pre-crack. Therefore, by providing the groove 214 on the bottom wall 2131 of the recess 213, when the pressure inside the casing 21 reaches a threshold, it is easier for the groove 214 to tear, ensuring the safety performance of the battery cell 20.

[0134] Furthermore, since the recess 213 is provided on the bottom wall portion 212 or the side wall portion 211 of the housing 21, when the battery cell 20 is inverted and the cover assembly 23 is facing down, such as when a car is in motion, the groove 214 is not easily scratched, making it less prone to damage and ensuring the service life of the battery cell 20.

[0135] In some embodiments, when both the side wall portion 211 and the bottom wall portion 212 of the housing 21 are provided with recesses 213, a scoring groove 214 may be provided on each recess 213. Of course, a scoring groove 214 may also be provided only on the recesses 213 of the side wall portion 211 or the bottom wall portion 212.

[0136] In some embodiments, the groove 214 is formed by the bottom wall 2131 of the recess 213 facing the inner surface of the electrode assembly 22 and recessing in a direction away from the electrode assembly 22. Of course, in some embodiments, the groove 214 may also be formed by the bottom wall 2131 of the recess 213 facing away from the outer surface of the electrode assembly 22 and recessing in a direction closer to the electrode assembly 22.

[0137] By recessing the bottom wall 2131 of the recess 213 towards the inner surface of the electrode assembly 22 or away from the outer surface of the electrode assembly 22, the wall thickness of the area corresponding to the recess 213 and the groove 214 is less than the wall thickness of other areas of the recess 213. When the internal pressure of the housing 21 is too high, the area corresponding to the bottom wall 2131 of the recess 213 and the groove 214 will tear first, which is conducive to the discharge of gas and avoids the housing 21 of the battery cell 20 from cracking.

[0138] In some embodiments, the groove 214 includes a first groove 2141, which extends along a straight line or an arc.

[0139] The first groove 2141 can extend in any direction on the bottom wall 2131 of the recess 213. When the first groove 2141 extends along a straight trajectory, it can form a straight groove.

[0140] Of course, the first groove 2141 can also extend along the arc trajectory to form an arc-shaped groove. The formed arc-shaped groove can be a circular arc groove or an elliptical arc groove.

[0141] The groove 214 adopts the above-mentioned structure, which is conducive to molding and allows the first groove 2141 to crack when the pressure inside the housing 21 exceeds the threshold, which is conducive to the discharge of gas and ensures the safety of the battery cell 20.

[0142] Please refer to Figure 11 , Figure 11 This is an isometric view of a battery cell according to some embodiments of this application. In some embodiments, the groove 214 further includes a second groove 2142, which extends along a straight trajectory, and the first groove 2141 and the second groove 2142 are intersected.

[0143] Both the first groove 2141 and the second groove 2142 can extend along a straight line or along an arc. Of course, in some embodiments, one of the first groove 2141 and the second groove 2142 can extend along a straight line and the other extends along an arc.

[0144] The angle between the first groove 2141 and the second groove 2142 in the extending direction can be an acute angle. Of course, the angle between them can also be 90°, that is, the first groove 2141 and the second groove 2142 can be perpendicular to each other. The lengths of the first groove 2141 and the second groove 2142 can be the same or different.

[0145] By setting the second groove 2142, when the pressure inside the housing 21 is greater than the threshold, it can be torn open at the first groove 2141 and the second groove 2142 to release the gas inside the housing 21, thus ensuring the safety performance of the battery cell 20.

[0146] In some embodiments, when the groove 214 includes a second groove 2142, both the first groove 2141 and the second groove 2142 extend along a straight trajectory, the extension direction of the first groove 2141 is perpendicular to the extension direction of the second groove 2142, and the first groove 2141 and the second groove 2142 together form a "+" shaped pattern.

[0147] The above configuration facilitates the formation of the groove 214 and enables the shell 21 to tear open at the first groove 2141 and the second groove 2142 when the pressure inside the shell 21 exceeds the threshold, thus facilitating the discharge of gas.

[0148] It is understood that when the groove 214 includes the first groove 2141 and the second groove 2142, the first groove 2141 and the second groove 2142 are not limited to forming a "+" shaped pattern. In some other embodiments, the first groove 2141 and the second groove 2142 can also form a "T" shaped pattern.

[0149] Please refer to Figure 12 as well as Figure 13 , Figure 12 This is an isometric view of a battery cell according to some embodiments of this application. Figure 13 This is an isometric view of a battery cell according to some embodiments of this application. It is understood that the scoring groove 214 of the battery cell 20 provided in the embodiments of this application is not limited to the form of including a first scoring groove 2141 and a second scoring groove 2142. When including a first scoring groove 2141, the scoring groove 214 may also include a third scoring groove 2143 and a fourth scoring groove 2144. The third scoring groove 2143 and the fourth scoring groove 2144 are spaced apart and relatively distributed, and the third scoring groove 2143 and the fourth scoring groove 2144 are respectively intersecting with the first scoring groove 2141.

[0150] The first groove 2141, the third groove 2143, and the fourth groove 2144 can all extend along a straight trajectory. Of course, the first groove 2141 can also extend along an arc trajectory, and the third groove 2143 and the fourth groove 2144 can extend along a straight trajectory, as long as the discharge requirement can be guaranteed when the pressure inside the housing 21 reaches the threshold.

[0151] With the above settings, when the pressure inside the housing 21 exceeds the threshold, it can be torn open at the first groove 2141, the third groove 2143 and the fourth groove 2144 to release the gas inside the housing 21 and ensure the safety performance of the battery cell 20.

[0152] In some embodiments, according to one aspect of the present application, the third groove 2143 and the fourth groove 2144 both extend along a straight trajectory. The third groove 2143 is disposed at one end of the first groove 2141 in its own extension direction and is connected to the first groove 2141. The fourth groove 2144 is disposed at the other end of the first groove 2141 in its extension direction and is connected to the first groove 2141. The first groove 2141, the third groove 2143 and the fourth groove 2144 are in the form of a "U" shaped pattern.

[0153] The above configuration facilitates the formation of the groove 214 and enables the casing 21 to tear open at the first groove 2141, the third groove 2143 and the fourth groove 2144 when the pressure inside the casing 21 exceeds the threshold, thereby releasing the gas inside the casing 21 and ensuring the safety performance of the battery cell 20.

[0154] It is understood that the above embodiments are all in the form of a combination of a first groove 2141 and a first groove 2142 or a third groove 2143 and a fourth groove 2144. This is an optional embodiment, but is not limited to the above method.

[0155] Please refer to Figure 14 , Figure 14 This is an isometric view of a battery cell according to some embodiments of this application. In some other embodiments, the groove 214 may include a pair of groove units 2145, which are spaced apart and symmetrically distributed. Each groove unit 2145 includes a fifth groove 2145a and a sixth groove 2145b. One end of the fifth groove 2145a intersects with one end of the sixth groove 2145b. In the pair of groove units 2145, the fifth groove 2145a of one unit is spaced apart from the fifth groove 2145a of the other unit and extends toward each other, and the sixth groove 2145b of one unit is spaced apart from the sixth groove 2145b of the other unit and extends in the same direction.

[0156] The groove 214 may include a pair of groove units 2145, or of course, two or more pairs of groove units 2145.

[0157] The extension directions of the fifth groove 2145a and the sixth groove 2145b can intersect or can be perpendicular, and the intersection of the fifth groove 2145a and the sixth groove 2145b can be smoothly transitioned.

[0158] With the above settings, when the internal pressure of the housing 21 exceeds the threshold, it can be torn open at the fifth groove 2145a and the sixth groove 2145b of each groove unit 2145 to release the gas inside the housing 21 and ensure the safety performance of the battery cell 20.

[0159] This application provides a battery, including the battery cell 20 provided in any of the above embodiments.

[0160] This application provides an electrical device, including the battery provided in any of the above embodiments, for providing electrical energy.

[0161] Please refer to Figure 15 , Figure 15 This is a flowchart illustrating a method for preparing a battery cell according to some embodiments of this application. In another aspect, according to an embodiment of this application, a method for preparing a battery cell 20 is provided, comprising:

[0162] S100. Provide an electrode assembly 22, which can be switched from a first form to a second form, and the volume of the electrode assembly 22 in the first form is smaller than the volume in the second form.

[0163] S200, a housing 21 is provided, and an electrode assembly 22 is inserted into the housing 21 through an opening in the housing 21. The housing 21 includes a side wall portion 211 and a bottom wall portion 212 connected to the side wall portion 211. At least one of the side wall portion 211 and the bottom wall portion 212 is provided with a recess 213 on the side facing the electrode assembly 22, which is recessed in a direction away from the electrode assembly 22. In the second configuration, the electrode assembly 22 partially extends into the cavity of the recess 213.

[0164] S300, Provide a cover assembly 23 to cover the opening.

[0165] The method for preparing battery cell 20 provided in this application embodiment can be used to prepare the battery cell 20 provided in the above embodiments. When the electrode assembly 22 expands and switches from the first form to the second form, the increased volume of the prepared battery cell 20 can extend into the inner cavity of the recess 213. Without reducing the volume of the electrode assembly 22, the deformation of the electrode assembly 22 can be absorbed by the recess 213 formed on the housing 21. This ensures the safety performance of the battery cell 20 during operation, while also ensuring the energy density of the battery cell 20 and optimizing the performance of the battery cell 20.

[0166] In another aspect, embodiments of this application also provide an apparatus for preparing a single battery cell 20, comprising:

[0167] The first assembly device is configured to provide an electrode assembly 22, which is capable of switching from a first form to a second form, wherein the volume of the electrode assembly 22 in the first form is smaller than the volume in the second form.

[0168] The second assembly device is configured to provide a housing 21 and insert an electrode assembly 22 into the housing 21 through an opening in the housing 21. The housing 21 includes a side wall portion 211 and a bottom wall portion 212 connected to the side wall portion 211. At least one of the side wall portion 211 and the bottom wall portion 212 has a recess 213 on the side facing the electrode assembly 22, which is recessed in a direction away from the electrode assembly 22. In the second configuration, the electrode assembly 22 partially extends into the cavity of the recess 213.

[0169] The third assembly device is configured to provide a cover assembly 23 and seal the cover assembly 23 over the opening.

[0170] The apparatus for preparing battery cells 20 provided in this application embodiment can be used to prepare the battery cells 20 provided in the above embodiments. When the electrode assembly 22 expands and switches from the first form to the second form, the increased volume of the prepared battery cell 20 can extend into the inner cavity of the recess 213. Without reducing the volume of the electrode assembly 22, the deformation of the electrode assembly 22 can be absorbed by the recess 213 formed on the housing 21. This ensures the safety performance of the battery cell 20 during operation, while also ensuring the energy density of the battery cell 20 and optimizing the performance of the battery cell 20.

[0171] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A single battery cell, comprising: An electrode assembly capable of switching from a first form to a second form, wherein the volume of the electrode assembly in the first form is smaller than the volume in the second form; A housing for accommodating the electrode assembly; A cover assembly for closing the open opening of the housing; The housing includes a sidewall portion and a bottom wall portion connected to the sidewall portion. At least one of the sidewall portion and the bottom wall portion has a recessed portion on the side facing the electrode assembly, which is recessed away from the electrode assembly. In the second configuration, the electrode assembly partially extends into the cavity of the recessed portion. The electrode assembly has a wound structure and includes a straight portion and an arc-shaped bend portion. The arc-shaped bend portion has a top region that is disposed away from the straight portion. The sidewall portion faces the top region and has the recessed portion. The orthographic projection of the top region on the sidewall portion is located on the bottom wall of the recessed portion, so that in the second configuration, the top region is located in the cavity of the recessed portion.

2. The battery cell according to claim 1, characterized in that, The minimum distance between the electrode assembly and the bottom wall of the recess in the second configuration is less than the minimum distance between the electrode assembly and the bottom wall of the recess in the first configuration.

3. The battery cell according to claim 1, characterized in that, The recess is formed by removing a portion of the housing by a predetermined depth through the inner surface of the housing.

4. The battery cell according to claim 1, characterized in that, The sidewall portion includes two first sidewall portions and two second sidewall portions. The two first sidewall portions are spaced apart and arranged opposite to each other, and the two second sidewall portions are spaced apart and arranged opposite to each other. Each second sidewall portion is connected to the two first sidewall portions respectively, and at least one first sidewall portion or at least one second sidewall portion is provided with the recess.

5. The battery cell according to claim 4, characterized in that, Each of the first sidewall portions is provided with the recess, and / or each of the second sidewall portions is provided with the recess.

6. The battery cell according to claim 4, characterized in that, The first sidewall faces the top region and is provided with the recess. The orthographic projection of the top region on the first sidewall is located on the bottom wall of the recess, so that in the second configuration, the top region is located in the inner cavity of the recess.

7. The battery cell according to any one of claims 1 to 6, wherein, The bottom wall of the recess is provided with a groove, which is configured to crack when the pressure of the gas inside the housing reaches a threshold, so as to discharge the gas to the outside of the housing.

8. The battery cell according to claim 7, wherein, The groove is formed by the bottom wall of the recess facing the inner surface of the electrode assembly and recessing away from the electrode assembly; or, the groove is formed by the bottom wall of the recess facing away from the outer surface of the electrode assembly and recessing towards the electrode assembly.

9. The battery cell according to claim 8, wherein, The groove includes a first groove, which extends along a straight line or an arc.

10. The battery cell according to claim 9, wherein, The groove also includes a second groove, which extends along a straight path, and the first groove and the second groove are intersecting.

11. The battery cell according to claim 10, wherein, Both the first groove and the second groove extend along a straight trajectory. The extension direction of the first groove is perpendicular to the extension direction of the second groove. The first groove and the second groove together form a "T" shaped pattern or a "+" shaped pattern.

12. The battery cell according to claim 9, wherein, The groove also includes a third groove and a fourth groove, which are spaced apart and relatively distributed, and intersect with the first groove respectively.

13. The battery cell according to claim 12, wherein, The third groove and the fourth groove both extend along a straight trajectory. The third groove is located at one end of the first groove in its extension direction and is connected to the first groove. The fourth groove is located at the other end of the first groove in its extension direction and is connected to the first groove. The first groove, the third groove and the fourth groove together form a "U" shaped pattern.

14. The battery cell according to claim 8, wherein, The groove includes a pair of groove units arranged in a symmetrical and spaced manner. Each groove unit includes a fifth groove and a sixth groove. One end of the fifth groove intersects with one end of the sixth groove. In the pair of groove units, the fifth groove of one unit is spaced apart from the fifth groove of the other unit and extends toward each other. The sixth groove of one unit is spaced apart from the sixth groove of the other unit and extends in the same direction.

15. A battery, wherein, Includes the battery cell as described in any one of claims 1 to 14.

16. An electrical appliance, wherein, Includes the battery as described in claim 15, the battery being used to provide electrical energy.

17. A method for preparing a battery cell, wherein, include: An electrode assembly is provided, which is capable of switching from a first form to a second form, wherein the volume of the electrode assembly in the first form is smaller than the volume in the second form. A housing is provided, into which the electrode assembly is inserted through an opening. The housing includes a sidewall portion and a bottom wall portion connected to the sidewall portion. At least one of the sidewall portion and the bottom wall portion has a recessed portion on the side facing the electrode assembly, which is recessed away from the electrode assembly. In a second configuration, the electrode assembly partially extends into the cavity of the recess. The electrode assembly has a wound structure and includes a straight portion and an arc-shaped bend portion. The arc-shaped bend portion has a top region disposed opposite to the straight portion. The sidewall portion faces the top region and has the recess. The orthographic projection of the top region onto the sidewall portion is located on the bottom wall of the recess, so that in the second configuration, the top region is located within the cavity of the recess. A cover assembly is provided to seal the opening.

18. An apparatus for preparing battery cells, wherein, include: A first assembly device is configured to provide an electrode assembly that can be switched from a first mode to a second mode, wherein the volume of the electrode assembly in the first mode is smaller than the volume in the second mode. A second assembly device is configured to provide a housing, into which the electrode assembly is inserted through an opening in the housing. The housing includes a sidewall portion and a bottom wall portion connected to the sidewall portion. At least one of the sidewall portion and the bottom wall portion has a recessed portion on the side facing the electrode assembly, which is recessed away from the electrode assembly. In a second configuration, the electrode assembly partially extends into the cavity of the recess. The electrode assembly has a wound structure and includes a straight portion and an arc-shaped bend portion. The arc-shaped bend portion has a top region disposed opposite to the straight portion. The sidewall portion faces the top region and has the recess. The orthographic projection of the top region onto the sidewall portion is located on the bottom wall of the recess, so that in the second configuration, the top region is located within the cavity of the recess. A third assembly device is configured to provide a cover assembly that seals the opening.

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