Cells, Batteries and Electronic Devices

Abstract

The embodiments of the present application provide a battery cell, a battery and an electronic device, which are applied in the field of electronic technology. The battery cell includes a battery cell shell and a bare battery cell, the bare battery cell is located in the battery cell shell, the battery cell shell includes a shell body and a shape memory layer, the shape memory layer is located on either side of the shell body or sandwiched between the film layers included in the shell body. Among them, the shape memory layer has an initial shape and a deformed shape, the initial shape is the memory shape restored when the temperature of the shape memory layer drops below the low-temperature phase memory temperature; the shape memory layer is used to apply a restraining force to the bare battery cell in the process of recovering from the deformed shape to the initial shape. Therefore, the embodiments of the present application provide a shape memory layer in the battery cell shell, and use the shape memory characteristics of the shape memory layer to apply a restraining force to the bare battery cell to suppress the expansion of the battery cell, improve the problem of excessive expansion thickness of the battery cell, and reduce the decay rate of the battery cell capacity.

Description

Technical Field

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

[0002] Lithium-ion batteries have been widely used in electronic devices such as mobile phones and laptops due to their advantages such as light weight, small size, high operating voltage, high energy density, high output power and high charging efficiency.

[0003] During the charge and discharge process of the battery cell in the lithium-ion battery, the negative electrode active material will repeatedly embed and extract lithium ions, causing the negative electrode active material to deform in volume. Taking the negative electrode active material as a silicon-based material as an example, the silicon-based material will produce a huge volume deformation, which will lead to the rapid attenuation of the battery cell capacity and the problem of excessive expansion thickness of the battery cell. Summary of the invention

[0004] The embodiments of the present application provide a battery cell, a battery, and an electronic device, which exert a restraining force on a bare battery cell through the shape memory characteristics of a shape memory layer in a battery cell casing, so as to reduce the decay rate of the battery cell capacity and inhibit the expansion of the battery cell.

[0005] In the first aspect, the embodiment of the present application proposes a battery cell, comprising: a battery cell shell, the battery cell shell comprising a shell body and a shape memory layer, the shape memory layer being located on either side of the shell body or sandwiched between film layers included in the shell body; a bare battery cell, located in the battery cell shell. The shape memory layer has an initial shape and a deformed shape, the initial shape being the memory shape restored when the temperature of the shape memory layer drops below the low temperature phase memory temperature; the shape memory layer is used to apply a restraining force to the bare battery cell during the process of recovering from the deformed shape to the initial shape.

[0006] In this way, by setting a shape memory layer in the battery cell shell, the shape memory characteristics of the shape memory layer can be used to apply a binding force to the bare battery cell in the process of recovering from the deformed shape to the initial shape. Therefore, during the cycle operation of the battery cell, the shape memory layer will continue to be in the process of recovering from the deformed shape to the initial shape, so that the shape memory layer can provide a stable and continuous binding force to the bare battery cell to slow down the volume deformation of the negative electrode active material, thereby inhibiting the expansion of the battery cell and improving the problem of excessive expansion thickness of the battery cell; and, by providing a stable and continuous binding force to the bare battery cell by the shape memory layer, the contact of the negative electrode active material can also be made closer, so as to inhibit the increase of the porosity of the negative electrode sheet in the battery cell, reduce the possibility of pulverization of the negative electrode active material or falling off from the negative electrode current collector, ensure the transmission path of lithium ions, and thus reduce the decay rate of the battery cell capacity.

[0007] In a possible implementation, the shell body includes a composite film, and the composite film includes a first film layer, a second film layer, and a third film layer stacked in sequence, and the first film layer, the second film layer, and the third film layer are sequentially arranged close to the bare battery core; wherein the material of the second film layer includes a metal material, and the first film layer, the second film layer, and the third film layer are film layers of different materials. In this way, the composite film can be used to encapsulate the bare battery core, and the weight of the composite film is relatively light, so the mass energy density of the battery core can be further reduced.

[0008] In a possible implementation, the shape memory layer is located on the side of the third film layer close to the bare cell. In this way, the shape memory layer is located on the side of the composite film close to the bare cell, which provides a possible location for the shape memory layer, making the structure of the cell shell more diverse.

[0009] In a possible implementation, the shape memory layer is located on the side of the first film layer away from the bare battery core. In this way, the shape memory layer is located on the side of the composite film away from the bare battery core, which provides another possible location for the shape memory layer, making the structure of the battery core shell more diverse.

[0010] In a possible implementation, the shape memory layer is located between the second film layer and the third film layer. In this way, the shape memory layer is sandwiched between the film layers included in the composite film, which provides another possible location for the shape memory layer, making the structure of the battery cell housing more diverse.

[0011] In a possible implementation, the shell body includes a metal shell, and the shape memory layer is located on a side of the metal shell close to the bare battery cell. In this way, the bare battery cell can be packaged with a metal shell, and its packaging reliability is relatively high and the structure is relatively simple.

[0012] In a possible implementation, the battery cell housing further includes an anti-corrosion layer, and the anti-corrosion layer is located between the shape memory layer and the bare battery cell. Thus, by providing the anti-corrosion layer between the shape memory layer and the bare battery cell, the corrosion of the shape memory layer by the electrolyte can be prevented.

[0013] In a possible implementation, the initial shape includes a plane or a shape corresponding to a pit with a first depth; the deformed shape includes a shape corresponding to a pit with a second depth, and the second depth is greater than the first depth. In this way, the shape memory layer can exert a restraining force on the bare battery cell during the process of recovering from the deformed shape to the initial shape.

[0014] In a possible implementation, the shape memory layer includes a first shape memory portion and a second shape memory portion connected to each other. The first shape memory portion has a pit, which is recessed from the second shape memory portion to the first shape memory portion, and the pit corresponding to the first shape memory portion is used to form a receiving cavity, which is used to accommodate a bare battery cell; or, the second shape memory portion has a pit, which is recessed from the first shape memory portion to the second shape memory portion, and the pit corresponding to the second shape memory portion is used to form a receiving cavity, which is used to accommodate a bare battery cell; or, both the first shape memory portion and the second shape memory portion have pits, the pit corresponding to the first shape memory portion is recessed from the second shape memory portion to the first shape memory portion, the pit corresponding to the second shape memory portion is recessed from the first shape memory portion to the second shape memory portion, and the pit corresponding to the first shape memory portion and the pit corresponding to the second shape memory portion are used together to form a receiving cavity, which is used to accommodate a bare battery cell. In this way, several different pit structures of the shape memory layer are provided, making the specific structure of the shape memory layer more diversified.

[0015] In a possible implementation, the shape memory layer also has a high-temperature phase memory shape, which is a memory shape restored when the temperature of the shape memory layer rises to above the high-temperature phase memory temperature; wherein the high-temperature phase memory temperature is greater than or equal to the low-temperature phase memory temperature, and the high-temperature phase memory shape is the same as the deformed shape. In this way, the shape memory layer can be a two-way shape memory layer, so that the shape memory layer has a relatively good deformation recovery ability.

[0016] In a possible implementation, the shape memory layer is used to form a deformed shape during the punching and forming process of the battery cell shell; or the shape memory layer is used to form a deformed shape during the punching and forming process of the battery cell shell and the hot pressing process of the battery cell. In this way, there is no need to provide an additional heating process to make the shape memory layer form the deformed shape, thereby simplifying the manufacturing process of the battery cell.

[0017] In a possible implementation, the material of the shape memory layer includes a shape memory alloy, and the shape memory alloy includes any one of a nickel-titanium alloy, a copper-nickel alloy, a copper-titanium alloy, a copper-aluminum alloy, a copper-zinc alloy, and an iron alloy.

[0018] In a possible implementation, the thickness of the shape memory layer is 5 micrometers to 50 micrometers. Thus, by properly setting the thickness of the shape memory layer, the size of the restraining force provided by the shape memory layer can be specifically changed.

[0019] In a possible implementation, the shape memory layer is a film layer without a hollow area; or the shape memory layer is a film layer with a hollow area, and the hollow area divides the shape memory layer into a preset pattern; the preset pattern includes one or more of a grid pattern, a Chinese-shaped pattern, a cross pattern, a well pattern, and a Chinese-shaped pattern. In this way, by making the shape memory layer into a film layer with a hollow area, it is possible to reduce the material used for the shape memory layer, thereby reducing the production cost of the battery cell.

[0020] In a possible implementation, the battery cell also includes an electrolyte, which is located in the battery cell housing; the bare battery cell includes a positive electrode sheet, a negative electrode sheet and a separator, which is located between the positive electrode sheet and the negative electrode sheet; the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer; the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer, and the material of the negative electrode active material layer includes a silicon-based material. In this way, using a silicon-based material as the negative electrode active material of the battery cell can improve the energy density of the battery cell.

[0021] In a second aspect, an embodiment of the present application provides a battery, comprising a battery protection board and the above-mentioned battery cell, wherein the battery protection board is connected to the battery cell.

[0022] In the third aspect, an embodiment of the present application proposes an electronic device, comprising a shell, a power management module, a charging management module and the above-mentioned battery; wherein a battery compartment is provided in the shell, and the battery is located in the battery compartment; and the battery is respectively connected to the power management module and the charging management module.

[0023] The possible implementation methods of the second and third aspects have effects similar to those of the first aspect and possible designs of the first aspect, and will not be elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram of the three-dimensional structure of an electronic device provided in an embodiment of the present application;

[0025] Figure 2 for Figure 1 A schematic diagram of the exploded structure of the electronic device shown;

[0026] Figure 3 A schematic diagram of the three-dimensional structure of a battery provided in an embodiment of the present application;

[0027] Figure 4 for Figure 3 A schematic diagram of the exploded structure of the battery shown;

[0028] Figure 5 A cross-sectional schematic diagram of a bare battery cell provided in an embodiment of the present application;

[0029] Figure 6 A cross-sectional schematic diagram of a first type of battery cell provided in an embodiment of the present application;

[0030] Figure 7 A cross-sectional schematic diagram of a second battery cell provided in an embodiment of the present application;

[0031] Figure 8 A cross-sectional schematic diagram of a third battery cell provided in an embodiment of the present application;

[0032] Fig. 9 A cross-sectional schematic diagram of a fourth battery cell provided in an embodiment of the present application;

[0033] Fig.10 A cross-sectional schematic diagram of a fifth battery cell provided in an embodiment of the present application;

[0034] Fig.11 A cross-sectional schematic diagram of a sixth battery cell provided in an embodiment of the present application;

[0035] Fig.12 A schematic diagram of the first shape memory layer provided in an embodiment of the present application before and after the pitting deformation;

[0036] Fig.13 A schematic diagram of the second shape memory layer provided in an embodiment of the present application before and after the pitting deformation;

[0037] Fig.14 A schematic diagram of the third shape memory layer provided in an embodiment of the present application before and after the pitting deformation;

[0038] Fig.15 Schematic diagram of the fourth shape memory layer before and after the pit deformation provided in an embodiment of the present application. DETAILED DESCRIPTION

[0039] In order to facilitate the clear description of the technical solutions of the embodiments of the present application, in the embodiments of the present application, the words "first" and "second" are used to distinguish the same items or similar items with basically the same functions and effects. For example, the first chip and the second chip are only used to distinguish different chips, and their order is not limited. Those skilled in the art can understand that the words "first" and "second" do not limit the quantity and execution order, and the words "first" and "second" do not necessarily limit them to be different.

[0040] It should be noted that in the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0041] In the embodiments of the present application, "at least one" refers to one or more, and "plurality" refers to two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, c can be single or multiple.

[0042] With the continuous development of lithium battery technology, lithium-ion batteries have been widely used in electronic devices such as mobile phones and laptops due to their advantages of light weight, small size, high operating voltage, high energy density, large output power and high charging efficiency. Lithium-ion batteries can provide power for electronic devices, allowing them to work normally.

[0043] In some lithium-ion battery cells, the negative electrode active material in the negative electrode sheet can be made of carbon-based materials, such as graphite. However, the theoretical maximum capacity of graphite is 372 mAh / g, which limits the capacity of the battery cell. As users have higher and higher requirements for the capacity of battery cells, battery cells using carbon-based materials as negative electrode active materials are gradually unable to meet market demand.

[0044] The theoretical gram capacity of silicon-based materials is much greater than that of carbon-based materials. For example, the theoretical gram capacity of silicon-based materials can be 4200mAh / g. Therefore, with the development of lithium-ion batteries, the negative electrode active materials in the battery cells of lithium-ion batteries have gradually evolved from carbon-based materials to silicon-based materials. Silicon-based materials have higher gram capacity, higher volumetric capacity, suitable lithium insertion potential and low cost, which can improve the energy density of lithium-ion batteries.

[0045] During the charge and discharge process of the battery cell, the silicon-based material will repeatedly embed and extract lithium ions. Specifically, during the charging process of the battery cell, the lithium ions in the positive active material of the positive electrode sheet of the battery cell are extracted, and the lithium ions move to the negative electrode sheet of the battery cell through the electrolyte. The lithium ions that reach the negative electrode sheet will be embedded in the silicon-based material of the negative electrode sheet; during the discharge process of the battery cell, the lithium ions embedded in the silicon-based material of the negative electrode sheet of the battery cell are extracted, and the lithium ions move to the positive electrode sheet of the battery cell through the electrolyte. The lithium ions that reach the positive electrode sheet will be re-embedded in the positive active material of the positive electrode sheet.

[0046] However, in the process of repeated embedding and extraction of lithium ions, silicon-based materials will produce huge volume deformation. For example, the full charge expansion rate of pure silicon material reaches 380%, which will lead to the problem of excessive expansion thickness of the battery cell. Moreover, when silicon-based materials produce huge volume deformation, the silicon particles in the silicon-based materials will also break, which will increase the porosity of the negative electrode sheet and even cause the silicon-based materials to pulverize or fall off the negative electrode current collector, ultimately leading to the problem of rapid capacity decay of the battery cell.

[0047] It should be noted that the cell capacity can also reflect the cell cycle performance to a certain extent. The cell cycle performance can refer to the number of cycles of the cell, that is, the number of charge and discharge times when the current cell capacity decreases to a certain specified value (such as 80%) of the initial capacity. Therefore, the rapid cell capacity decay also indicates a sharp decline in the cell cycle performance to a certain extent.

[0048] In related technologies, such as power cells in the field of electric vehicles, since the space for placing power cells is relatively large, some power cells may use composite metal splints as brackets to apply restraint force to the power cells to reduce the capacity attenuation rate of the power cells and inhibit the expansion of the power cells.

[0049] However, for the battery cells installed in electronic devices, such as consumer battery cells, the requirements for volume energy density and mass energy density are relatively high. If the battery cells installed in the electronic device also use composite metal splints to apply restraining force, due to the relatively large weight and volume of the composite metal splints, this will cause the weight and volume of the battery cells in the electronic device to be relatively large, and then cause the volume energy density and mass energy density of the battery cells installed in the electronic device to be significantly reduced. Therefore, the above-mentioned method of applying restraining force in power battery cells using composite metal splints is not suitable for battery cells installed in electronic devices.

[0050] Among them, volume energy density refers to the electric energy released per average unit volume of the battery cell, and mass energy density refers to the electric energy released per average unit mass of the battery cell.

[0051] Based on this, the embodiment of the present application provides a battery cell, a battery and an electronic device, wherein the battery cell includes a battery cell shell and a bare battery cell, wherein the bare battery cell is located in the battery cell shell, and the battery cell shell includes a shell body and a shape memory layer, wherein the shape memory layer is located on either side of the shell body or sandwiched between the film layers included in the shell body. The shape memory layer has an initial shape and a deformed shape, wherein the initial shape is a memory shape restored when the temperature of the shape memory layer drops below the low-temperature phase memory temperature; and the shape memory layer is used to apply a restraining force to the bare battery cell during the process of restoring from the deformed shape to the initial shape.

[0052] Therefore, by setting a shape memory layer in the battery cell shell, the shape memory characteristics of the shape memory layer can be used to apply a binding force to the bare battery cell in the process of recovering from the deformed shape to the initial shape. In this way, during the cycle operation of the battery cell (i.e., during the charging and discharging process of the battery cell), the shape memory layer will continue to be in the process of recovering from the deformed shape to the initial shape, so that the shape memory layer can provide a stable and continuous binding force to the bare battery cell to slow down the volume deformation of the negative electrode active material, thereby inhibiting the expansion of the battery cell and improving the problem of excessive expansion thickness of the battery cell; and, by providing a stable and continuous binding force to the bare battery cell by the shape memory layer, the contact of the negative electrode active material can also be made closer, so as to inhibit the increase of the porosity of the negative electrode sheet, reduce the possibility of pulverization of the negative electrode active material or falling off from the negative electrode current collector, ensure the transmission path of lithium ions, and thus reduce the decay rate of the battery cell capacity.

[0053] In addition, since the mass and volume of the shape memory layer are relatively small, the mass and volume of the battery cell will not increase significantly when the shape memory layer is provided in the battery cell casing, so that the volume energy density and mass energy density of the battery cell will not decrease significantly.

[0054] In summary, the embodiments of the present application suppress the expansion of the battery cell to improve the problem of excessive expansion thickness of the battery cell and reduce the attenuation rate of the battery cell capacity without significantly reducing the volume energy density and mass energy density of the battery cell.

[0055] The embodiment of the present application provides an electronic device, which can be any device including a battery. Specifically, the electronic device includes but is not limited to a mobile phone, a tablet computer, a notebook computer, a wearable device (such as a smart watch, a smart bracelet, etc.), an e-book reader, a laptop computer, a personal digital assistant (PDA), a personal computer, a virtual reality (VR) device, an augmented reality (AR) device, a camera, and an in-vehicle device. The embodiment of the present application does not limit the specific technology and specific device form used by the electronic device.

[0056] For example, Figure 1 A schematic diagram of the three-dimensional structure of an electronic device provided in an embodiment of the present application, Figure 2 for Figure 1 The exploded structure diagram of the electronic device shown is shown. Figure 1 and Figure 2 As shown, taking the electronic device as a mobile phone as an example, the electronic device may include a display screen 10 , a housing 20 and a battery 30 , and the display screen 10 is mounted on the housing 20 .

[0057] The display screen 10 is used to realize the display function. The display screen 10 can be a liquid crystal display (LCD), an organic light-emitting diode (OLED) display screen, an active-matrix organic light-emitting diode or an active-matrix organic light-emitting diode (AMOLED) display screen, a flexible light-emitting diode (FLED) display screen, a Miniled display screen, a MicroLed display screen, a Micro-oled display screen, a quantum dot light-emitting diode (QLED) display screen, etc.

[0058] The housing 20 includes a frame 21, a back cover 22, and a middle plate 23. The frame 21 is located between the display screen 10 and the back cover 22, and the frame 21 is fixed to the back cover 22. In some embodiments, the frame 21 and the back cover 22 can be an integrally formed structure to enhance the compactness of the electronic device and reduce the possibility of the electronic components inside the electronic device being damaged due to the detachment of the back cover 22 when the electronic device falls. In other embodiments, the frame 21 can also be fixed to the back cover 22 by gluing or other means to facilitate the repair or replacement of electronic components such as batteries and motherboards inside the electronic device, thereby increasing the flexibility of use of the electronic device.

[0059] Furthermore, the display screen 10 can be fixed on the frame 21. Exemplarily, the display screen 10 can be fixed on the frame 21 by gluing or other means. In this way, the display screen 10, the frame 21 and the back cover 22 can be surrounded to form an internal accommodation space of the electronic device, and the internal accommodation space is used to accommodate electronic components such as the middle plate 23, the battery 30, the camera module and the main board.

[0060] The middle plate 23 is located in the internal accommodation space of the electronic device and is fixed to the inner surface of the frame 21. Exemplarily, the middle plate 23 is fixed to the frame 21 by welding, or the middle plate 23 and the frame 21 are integrally formed. The middle plate 23 can be used as a supporting structure inside the electronic device, and can be used to support electronic components such as a camera module and a motherboard.

[0061] A battery compartment 24 is provided in the housing 20, and the battery compartment 24 is used to accommodate the battery 30, that is, the battery 30 can be located in the battery compartment 24. The battery compartment 24 has an opening. For example, the middle plate 23 and the frame 21 can be spliced ​​to define a battery compartment 24 with an opening. The opening of the battery compartment 24 is arranged close to the rear cover 22, and the opening of the battery compartment 24 can be covered by the rear cover 22.

[0062] In some embodiments, the main board can be located between the middle board 23 and the back cover 22, and the main board is located on one side of the battery compartment 24 (such as Figure 2 In addition, a charging management module and a power management module may be provided on the main board, and the battery 30 is electrically connected to the power management module and the charging management module, respectively.

[0063] The charging management module is used to receive charging input from a charger. The charger can be a wireless charger or a wired charger. In some wired charging embodiments, the charging management module can receive charging input from a wired charger through a universal serial bus (USB) interface. In some wireless charging embodiments, the charging management module can receive wireless charging input through a wireless charging coil of an electronic device. While the charging management module is charging the battery 30, it can also power the electronic device through the power management module.

[0064] The power management module is used to receive input from the battery 30 and / or the charging management module to power the electronic components in the electronic device, such as the display screen 10, the camera module, the main board, and the speaker module. The power management module can also be used to monitor parameters such as battery capacity, battery cycle number, battery health status (leakage, impedance), etc. In other embodiments, the power management module and the charging management module can also be set in the same device.

[0065] In the embodiment of the present application, the battery 30 may include but is not limited to a nickel-cadmium battery, a nickel-metal hydride battery, a lithium-ion battery, or other types of batteries. In addition, the number of the battery 30 in the embodiment of the present application may be multiple or one, and the specific number and arrangement of the battery 30 in the embodiment of the present application may be set according to actual needs. In the following description, the battery 30 is described as a lithium-ion battery, and the lithium-ion battery may be a liquid lithium-ion battery, a solid lithium-ion battery, or a semi-solid lithium-ion battery.

[0066] For example, Figure 3 A schematic diagram of the three-dimensional structure of a battery provided in an embodiment of the present application, Figure 4 for Figure 3 The exploded structure of the battery is shown in Figure 1. Figure 3 and Figure 4As shown, the battery 30 includes a battery cell 31 and a battery protection board 32 , and the battery protection board 32 is electrically connected to the battery cell 31 .

[0067] The battery protection board 32 may be an integrated circuit board that protects the battery cell 31 and is used to prevent the battery cell 31 from overcharging, overdischarging, overcurrent, short circuit, and ultra-high temperature charging and discharging. The battery protection board 32 may realize electrical connection between the battery cell 31 and the main board.

[0068] The battery cell 31 includes a battery cell housing 311, a bare battery cell 312 and an electrolyte (not shown). The battery cell housing 311 contains an electrolyte, that is, the electrolyte is located in the battery cell housing 311. In addition, the bare battery cell 312 is located in the battery cell housing 311 and is immersed in the electrolyte.

[0069] The cell casing 311 refers to the portion of the cell 31 used to encapsulate and protect the bare cell 312 and the electrolyte. The shape of the cell casing 311 includes but is not limited to a cuboid, a cylinder or other special-shaped structures.

[0070] The bare cell 312 may be a wound bare cell or a stacked bare cell, which is not limited in the embodiment of the present application.

[0071] Figure 5 A cross-sectional schematic diagram of a bare battery cell is shown. Figure 5 As shown, the bare cell 312 is formed by stacking and winding a positive electrode sheet 3121, a separator 3123, a negative electrode sheet 3122 and a separator 3123 in sequence.

[0072] That is, the bare cell 312 includes a positive electrode sheet 3121, a negative electrode sheet 3122 and a separator 3123, wherein the separator 3123 is located between the positive electrode sheet 3121 and the negative electrode sheet 3122, and the separator 3123 can separate the positive electrode sheet 3121 from the negative electrode sheet 3122, and play the role of insulation isolation, thereby preventing the two electrodes from directly contacting each other and causing a short circuit. The separator 3123 can be a polyolefin porous membrane.

[0073] The positive electrode sheet 3121 includes a positive electrode current collector 31211 and a positive electrode active material layer 31212. The positive electrode active material layer 31212 may be located on one surface of the positive electrode current collector 31211 or on two oppositely disposed surfaces of the positive electrode current collector 31211. Figure 5 The description is made by taking the case where the positive electrode active material layer 31212 is located on one surface of the positive electrode current collector 31211 as an example.

[0074] The material of the positive electrode current collector 31211 may be aluminum. The material of the positive electrode active material layer 31212 is a positive electrode active material, which can provide the insertion and extraction of lithium ions and improve the conductivity of lithium ions. For example, compounds that can insert lithium ions, such as lithium oxides and composite oxides thereof, may be selected as positive electrode active materials. These compounds may include metal lithium oxides, such as at least one of lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium manganese oxide (LiMn2O4), lithium iron phosphate, lithium nickel cobalt manganese oxide, and lithium nickel cobalt aluminum oxide.

[0075] The negative electrode sheet 3122 includes a negative electrode current collector 31221 and a negative electrode active material layer 31222. The negative electrode active material layer 31222 may be located on one surface of the negative electrode current collector 31221 or on two oppositely disposed surfaces of the negative electrode current collector 31221. Figure 5 The description is made by taking the case where the negative electrode active material layer 31222 is located on one surface of the negative electrode current collector 31221 as an example.

[0076] The material of the negative electrode current collector 31221 may be copper. The material of the negative electrode active material layer 31222 is a negative electrode active material, which may include but is not limited to a silicon-based material. Taking the negative electrode active material as a silicon-based material as an example, that is, the negative electrode sheet 3122 of the bare battery cell 312 includes a silicon-based material. In some embodiments, the silicon-based material may include at least one of elemental silicon, silicon alloy, silicon oxide, and silicon carbon.

[0077] The electrolyte exists in the gap of the bare battery 312 inside the battery shell 311, and is used as a carrier for transmitting lithium ions in the battery 31. The electrolyte is generally prepared from raw materials such as high-purity organic solvents, electrolyte lithium salts, and necessary additives under certain conditions and in a certain proportion.

[0078] In addition, the bare cell 312 may further include a first pole tab 313 and a second pole tab 314 , one of the first pole tab 313 and the second pole tab 314 being a positive pole tab, and the other being a negative pole tab.

[0079] Exemplarily, one end of the first pole tab 313 is electrically connected to the positive electrode collector 31211 of the positive electrode sheet 3121. Specifically, the first pole tab 313 can be connected to the positive electrode collector 31211 of the positive electrode sheet 3121 by welding, pressing, etc. Correspondingly, one end of the second pole tab 314 can also be electrically connected to the negative electrode collector 31221 of the negative electrode sheet 3122. Specifically, the second pole tab 314 can be connected to the negative electrode collector 31221 of the negative electrode sheet 3122 by welding, pressing, etc.

[0080] Furthermore, the other ends of the first electrode tab 313 and the second electrode tab 314 can pass through the battery cell housing 311 and extend out of the battery cell housing 311 , and be electrically connected to the battery protection board 32 .

[0081] Combine the following Figures 6 to 11 The schematic cross-sectional views of several battery cells shown in the figure illustrate in detail the specific structure of the battery cell housing 311 in the embodiment of the present application.

[0082] For example, Figure 6 The cross-sectional schematic diagram of the first battery cell provided in the embodiment of the present application is shown in FIG. Figure 6 As shown, the battery cell housing 311 includes a housing body 3111 and a shape memory layer 3112 .

[0083] In some embodiments, the housing body 3111 includes a composite film, and the composite film includes a first film layer 31111, a second film layer 31112, and a third film layer 31113 that are sequentially stacked, and the first film layer 31111, the second film layer 31112, and the third film layer 31113 are sequentially arranged close to the bare battery core 312. That is, the second film layer 31112 is located on a side of the first film layer 31111 close to the bare battery core 312, and the third film layer 31113 is located on a side of the second film layer 31112 close to the bare battery core 312.

[0084] The material of the second film layer 31112 includes a metal material, and the first film layer 31111, the second film layer 31112 and the third film layer 31113 are film layers made of different materials.

[0085] The first film layer 31111 has the functions of protecting against pollution, corrosion and external damage; the material of the first film layer 31111 can be at least one of polyamide (or nylon), polyolefin, polycarbonate and fluororesin. The second film layer 31112 is used to block moisture and air; the material of the second film layer 31112 can be metal or metal alloy, such as the metal can be any one of aluminum, iron, silver, copper, nickel, manganese, tin, titanium, zirconium and vanadium. The third film layer 31113 can also be called a sealing layer, which has the function of sealing and preventing the electrolyte from corroding the second film layer 31112; the material of the third film layer 31113 can be at least one of polyethylene, polypropylene, esters of polyethylene or polypropylene, and ion crosslinked products of polyethylene and polypropylene.

[0086] Exemplarily, the composite film may be an aluminum-plastic film, the second film layer 31112 in the aluminum-plastic film is an aluminum layer, the first film layer 31111 in the aluminum-plastic film may be a nylon layer, and the third film layer 31113 in the aluminum-plastic film may be a polypropylene layer.

[0087] like Figure 6As shown, the shape memory layer 3112 is located on the side of the third film layer 31113 close to the bare battery core 312. In this way, the shape memory layer 3112 can be used as an inner wrapping layer of the bare battery core 312, and is located on the side of the composite film close to the bare battery core 312.

[0088] Taking the bare cell 312 as a rectangular parallelepiped as an example, the bare cell 312 may include six surfaces. The six surfaces of the bare cell 312 may be provided with a shape memory layer 3112; or, the shape memory layer 3112 may be provided on four of the surfaces of the bare cell 312, and the shape memory layer 3112 may not be provided on the remaining two surfaces, and the surfaces not provided with the shape memory layer 3112 include: the surface on the side where the tabs of the bare cell 312 extend and the surface opposite to the surface on the side where the tabs extend.

[0089] During the manufacturing process of the battery cell 31, the shell body 3111 may be punched using a punching process, so that the shell body 3111 has a receiving cavity for receiving the bare battery cell 312. Therefore, in the embodiment of the present application, the shell body 3111 may be punched while the shape memory layer 3112 is punched, so that the shape memory layer 3112 is deformed to form a deformed shape, and the deformed shape is also used to form the receiving cavity.

[0090] Before the shell body 3111 and the shape memory layer 3112 are punched, the shell body 3111 and the shape memory layer 3112 are separately provided, and the shape memory layer 3112 is in the initial shape. The shell body 3111 and the shape memory layer 3112 may be stacked together and then punched; or, the shell body 3111 and the shape memory layer 3112 may be punched separately and then stacked together.

[0091] After the shell body 3111 and the shape memory layer 3112 are punched, the battery shell 311 can have a cavity for accommodating the bare battery 312. Then, the prepared bare battery 312 can be placed in the cavity of the battery shell 311 and then packaged. The packaged battery 31 will be processed by a hot pressing process later.

[0092] In some embodiments, the packaged battery cell 31 is placed in a hot pressing forming cabinet, and the forming temperature and forming pressure parameters of the forming cabinet are set, such as the forming temperature is 50° C. to 80° C., and the forming pressure is 0.5 MPa to 1 MPa. Therefore, during the hot pressing forming process, due to the effects of temperature and pressure, the shape memory layer 3112 can also be further made to maintain a high temperature memory process to further maintain the deformed shape.

[0093] Therefore, in the embodiment of the present application, the shape memory layer 3112 is used to form the deformed shape during the punching and forming process of the battery cell housing 311 and the hot pressing process of the battery cell 31 .

[0094] That is to say, the embodiment of the present application can utilize the punching and forming process and the hot pressing process in the production process of the battery cell 31 as the high-temperature memory process of the shape memory layer 3112 to form the deformed shape, without the need to provide an additional heating treatment process to make the shape memory layer 3112 form the deformed shape, thereby simplifying the production process of the battery cell 31.

[0095] Of course, the embodiment of the present application can also form the deformed shape only during the punching and forming process of the battery cell housing 311, rather than during the hot pressing process of the battery cell 31, to further enable the shape memory layer 3112 to maintain the deformed shape. In this way, the shape memory layer is used to form the deformed shape during the punching and forming process of the battery cell housing 311.

[0096] Combine the following Figures 12 to 15 The schematic diagrams of several shape memory layers before and after the pitting deformation are shown, which illustrate in detail several different initial shapes and deformed shapes of the shape memory layer 3112 in the embodiment of the present application.

[0097] For example, Fig.12 This is a schematic diagram of the first shape memory layer provided in the embodiment of the present application before and after the pitting deformation. Fig.12 As shown, the shape memory layer 3112 may include a first shape memory film 31121 and a second shape memory film 31122 , and the shape memory layer 3112 is manufactured by the first shape memory film 31121 and the second shape memory film 31122 .

[0098] like Fig.12 As shown in (a) , the initial shapes of the first shape memory film 31121 and the second shape memory film 31122 are both planar.

[0099] During the manufacturing process of the battery cell 31, the housing body 3111 may also include a first housing (not shown). Fig.12 ) and a second housing (not shown in Fig.12 As shown in FIG. 1 , the second shell and the second shape memory film 31122 are stacked together and punched, so that the second shell and the second shape memory film 31122 are deformed. Fig.12As shown in (b), the second shape memory film 31122 after deformation has a pit, and the depth of the pit is the second depth h2; correspondingly, the second shell after deformation also has a pit, and the pit corresponding to the second shell and the pit corresponding to the second shape memory film 31122 are consistent in shape, depression direction, etc., and the pit corresponding to the second shell and the pit corresponding to the second shape memory film 31122 are stacked together.

[0100] Since the shape memory layer 3112 can be located on the inner side of the shell body 3111, after the second shell and the second shape memory film 31122 are punched to form a pit, the bare cell 312 can be placed in the pit corresponding to the second shape memory film 31122. Then, the first shape memory film 31121 and the first shell are sequentially covered on the bare cell 312. For example, if both the first shell and the second shell are aluminum-plastic films, and the inner layer of the aluminum-plastic film is a polypropylene layer, the polypropylene layer can be melted by heating to bond, so that the first shape memory film 31121 and the second shape memory film 31122 form the shape memory layer 3112, and the first shell and the second shell form the shell body 3111. Fig.12 Reference numeral 40 shown in (b) indicates a position where the polypropylene layer is melt-bonded.

[0101] Since the shape memory layer 3112 is made by the first shape memory film 31121 and the second shape memory film 31122, the initial shape of the shape memory layer 3112 includes a plane shape, and the deformed shape of the shape memory layer 3112 includes a shape corresponding to the pit having the second depth h2. At this time, the pit corresponding to the second shape memory film 31122 is recessed in the direction from the first shape memory film 31121 to the second shape memory film 31122.

[0102] like Fig.12 As shown in (c) in FIG. 1 , after the battery cell 31 is placed in the electronic device, during the charging and discharging process of the electronic device, that is, under normal working conditions, the shape memory layer 3112 will be Fig.12 The deformed shape shown in (b) is oriented as shown in Fig.12 In the process of recovery, the shape memory layer 3112 will exert a restraining force on the bare battery cell 312, and the direction of the restraining force applied can be as follows: Fig.12 The direction of the arrow shown in (c).

[0103] In some other embodiments, the first shell and the first shape memory film 31121 may be stacked together to perform a punching process, so that the first shell and the first shape memory film 31121 are deformed. The deformed first shape memory film 31121 has a pit, and the depth of the pit is the second depth h2; accordingly, the deformed first shell also has a pit, and the pit corresponding to the first shell and the pit corresponding to the first shape memory film 31121 are consistent in shape and depression direction, and the pit corresponding to the first shell and the pit corresponding to the first shape memory film 31121 are stacked together.

[0104] Since the shape memory layer 3112 can be located on the inner side of the shell body 3111, after the first shell and the first shape memory film 31121 are punched to form a pit, the bare cell 312 can be placed in the pit corresponding to the first shape memory film 31121. Then, the second shape memory film 31122 and the second shell are sequentially covered on the bare cell 312. For example, if both the first shell and the second shell are aluminum-plastic films, and the inner layer of the aluminum-plastic film is a polypropylene layer, the polypropylene layer can be melted by heating to bond, so that the first shape memory film 31121 and the second shape memory film 31122 form the shape memory layer 3112, and the first shell and the second shell form the shell body 3111.

[0105] Therefore, the initial shape of the shape memory layer 3112 includes a plane shape, and the deformed shape of the shape memory layer 3112 includes a shape corresponding to the pit having the second depth h2. At this time, the pit corresponding to the first shape memory film 31121 is recessed in the direction from the second shape memory film 31122 to the first shape memory film 31121.

[0106] In some other embodiments, a single shape memory film (such as the first shape memory film 31121 or the second shape memory film 31122) and a single shell (such as the first shell or the second shell) can also be used to manufacture the obtained battery cell 31. Taking the single shape memory film as the first shape memory film 31121 and the single shell as the first shell as an example, the first shell and the first shape memory film 31121 can be stacked together for punching, so that the first shell and the first shape memory film 31121 are deformed. The deformed first shape memory film 31121 has a pit, and the depth of the pit is the second depth h2; accordingly, the deformed first shell also has a pit.

[0107] Since the shape memory layer 3112 can be located on the inner side of the shell body 3111, after the first shell and the first shape memory film 31121 are punched to form a pit, the bare cell 312 can be placed in the pit corresponding to the first shape memory film 31121. Then, the first shape memory film 31121 and the first shell are folded in half, so that part of the first shape memory film 31121 and part of the first shell are sequentially covered on the bare cell 312. For example, if the first shell is an aluminum-plastic film and the inner layer of the aluminum-plastic film is a polypropylene layer, the polypropylene layer can be melted by heating for bonding, so that the folded first shape memory film 31121 forms the shape memory layer 3112, and the folded first shell forms the shell body 3111.

[0108] For example, Fig.13 This is a schematic diagram of the second shape memory layer provided in the embodiment of the present application before and after the pitting deformation. Fig.13 As shown, the shape memory layer 3112 may include a first shape memory film 31121 and a second shape memory film 31122 , and the shape memory layer 3112 is manufactured by the first shape memory film 31121 and the second shape memory film 31122 .

[0109] like Fig.13 As shown in (a), the initial shape of the first shape memory film 31121 is a plane, and the initial shape of the second shape memory film 31122 is a shape corresponding to a pit having a first depth h1.

[0110] During the manufacturing process of the battery cell 31, the housing body 3111 may also include a first housing (not shown). Fig.13 ) and a second housing (not shown in Fig.13 As shown in FIG. 1 , the second shell and the second shape memory film 31122 are stacked together and punched, so that the second shell and the second shape memory film 31122 are deformed. Fig.13 As shown in (b), the second shape memory film 31122 after deformation has a pit, and the depth of the pit is the second depth h2; correspondingly, the second shell after deformation also has a pit, and the pit corresponding to the second shell and the pit corresponding to the second shape memory film 31122 are consistent in shape, depression direction, etc., and the pit corresponding to the second shell and the pit corresponding to the second shape memory film 31122 are stacked together.

[0111] Since the shape memory layer 3112 can be located on the inner side of the shell body 3111, after the second shell and the second shape memory film 31122 are punched to form a pit, the bare cell 312 can be placed in the pit corresponding to the second shape memory film 31122. Then, the first shape memory film 31121 and the first shell are sequentially covered on the bare cell 312. For example, if both the first shell and the second shell are aluminum-plastic films, and the inner layer of the aluminum-plastic film is a polypropylene layer, the polypropylene layer can be melted by heating to bond, so that the first shape memory film 31121 and the second shape memory film 31122 form the shape memory layer 3112, and the first shell and the second shell form the shell body 3111. Fig.13 Reference numeral 40 shown in (b) indicates a position where the polypropylene layer is melt-bonded.

[0112] Since the shape memory layer 3112 is made by the first shape memory film 31121 and the second shape memory film 31122, the initial shape of the shape memory layer 3112 includes a shape corresponding to the pit with the first depth h1, and the deformed shape of the shape memory layer 3112 includes a shape corresponding to the pit with the second depth h2, and the second depth h2 is greater than the first depth h1. At this time, the pit corresponding to the second shape memory film 31122 is recessed in the direction from the first shape memory film 31121 to the second shape memory film 31122.

[0113] like Fig.13 As shown in (c) in FIG. 1 , after the battery cell 31 is placed in the electronic device, during the charging and discharging process of the electronic device, that is, under normal working conditions, the shape memory layer 3112 will be Fig.13 The deformed shape shown in (b) is oriented as shown in Fig.13 In the process of recovery, the shape memory layer 3112 will exert a restraining force on the bare battery cell 312, and the direction of the restraining force applied can be as follows: Fig.13 The direction of the arrow shown in (c).

[0114] It should be noted that, in the embodiment of the present application, the first shell and the first shape memory film 31121 may be punched to form a pit respectively, and after the bare cell 312 is placed in the pit corresponding to the first shape memory film 31121, the second shape memory film 31122 and the second shell are sequentially covered on the bare cell 312. Alternatively, a single shape memory film and a single shell may be punched to form a pit respectively, and after the bare cell 312 is placed in the pit corresponding to the shape memory film, the shape memory film and the shell are folded in half and covered on the bare cell 312.

[0115] Understandably, Fig.13The initial shape of the shape memory layer 3112 in the embodiment is the shape corresponding to the pit having the first depth h1, relative to Fig.12 In the manner that the initial shape of the shape memory layer 3112 is planar, Fig.13 The restraining force exerted by the shape memory layer 3112 on the bare battery cell 312 will be less than Fig.12 The shape memory layer 3112 in the bare battery cell 312 exerts a restraining force on the bare battery cell 312. In actual use, a plane shape or a shape corresponding to a pit with a first depth h1 can be selected as the initial shape of the shape memory layer 3112 according to factors such as the expansion rate of the bare battery cell 312 and the compaction of the pole piece in the bare battery cell 312.

[0116] In summary, combined Fig.12 and Fig.13 Correspondingly, the shape memory layer 3112 may include a first shape memory portion and a second shape memory portion connected to each other. The first shape memory portion is a first shape memory film 31121, and the second shape memory portion is a second shape memory film 31122; or, the first shape memory portion and the second shape memory portion are formed by folding the same shape memory film (such as the first shape memory film 31121 or the second shape memory film 31122) in half.

[0117] The first shape memory portion has a pit, which is sunken from the second shape memory portion to the direction of the first shape memory portion, and the pit corresponding to the first shape memory portion is used to form a receiving cavity, and the receiving cavity is used to receive the bare battery cell 312. Alternatively, the second shape memory portion has a pit, which is sunken from the first shape memory portion to the direction of the second shape memory portion, and the pit corresponding to the second shape memory portion is used to form a receiving cavity, and the receiving cavity is used to receive the bare battery cell 312.

[0118] For example, Fig.14 This is a schematic diagram of the third shape memory layer provided in the embodiment of the present application before and after the pitting deformation. Fig.14 As shown, the shape memory layer 3112 may include a first shape memory film 31121 and a second shape memory film 31122 , and the shape memory layer 3112 is manufactured by the first shape memory film 31121 and the second shape memory film 31122 .

[0119] like Fig.14 As shown in (a) , the initial shapes of the first shape memory film 31121 and the second shape memory film 31122 are both planar.

[0120] During the manufacturing process of the battery cell 31, the housing body 3111 may also include a first housing (not shown). Fig.14 ) and a second housing (not shown in Fig.14As shown in the figure, the first shell and the first shape memory film 31121 can be stacked together and punched, so that the first shell and the first shape memory film 31121 are deformed, and the second shell and the second shape memory film 31122 can be stacked together and punched, so that the second shell and the second shape memory film 31122 are also deformed.

[0121] like Fig.14 As shown in (b), the deformed first shape memory film 31121 has a pit, and the deformed first shell also has a pit. The pit corresponding to the first shell is consistent with the pit corresponding to the first shape memory film 31121 in shape and depression direction, and the pit corresponding to the first shell is stacked with the pit corresponding to the first shape memory film 31121. In addition, the deformed second shape memory film 31122 has a pit, and the deformed second shell also has a pit. The pit corresponding to the second shell is consistent with the pit corresponding to the second shape memory film 31122 in shape and depression direction, and the pit corresponding to the second shell is also stacked with the pit corresponding to the second shape memory film 31122.

[0122] Since the shape memory layer 3112 can be located on the inner side of the shell body 3111, after the first shell and the first shape memory film 31121, and the second shell and the second shape memory film 31122 are punched to form pits, the bare battery cell 312 can be placed in the pit corresponding to the first shape memory film 31121 or the second shape memory film 31122.

[0123] Taking the bare cell 312 placed in the pit corresponding to the second shape memory film 31122 as an example, the first shape memory film 31121 and the first shell can be sequentially covered on the bare cell 312, and the pit corresponding to the first shape memory film 31121 is arranged opposite to the pit corresponding to the second shape memory film 31122. Taking the first shell and the second shell as an example, both of which are aluminum-plastic films, and the inner layer of the aluminum-plastic film is a polypropylene layer, the polypropylene layer can be melted by heating for bonding, so that the first shape memory film 31121 and the second shape memory film 31122 form a shape memory layer 3112, and the first shell and the second shell form a shell body 3111. Fig.14 Reference numeral 40 shown in (b) indicates a position where the polypropylene layer is melt-bonded.

[0124] Since the shape memory layer 3112 is made by the first shape memory film 31121 and the second shape memory film 31122, the initial shape of the shape memory layer 3112 includes a plane shape, and the deformed shape of the shape memory layer 3112 includes a shape corresponding to a pit having a second depth h2. Specifically, the sum of the depth of the pit corresponding to the first shape memory film 31121 and the depth of the pit corresponding to the second shape memory film 31122 is equal to the second depth h2. For example, the depth of the pit corresponding to the first shape memory film 31121 can be h2 / 2, and the depth of the pit corresponding to the second shape memory film 31122 can also be h2 / 2.

[0125] At this time, the pit corresponding to the first shape memory film 31121 is recessed in the direction from the second shape memory film 31122 to the first shape memory film 31121 , and the pit corresponding to the second shape memory film 31122 is recessed in the direction from the first shape memory film 31121 to the second shape memory film 31122 .

[0126] like Fig.14 As shown in (c) in FIG. 1 , after the battery cell 31 is placed in the electronic device, during the charging and discharging process of the electronic device, that is, under normal working conditions, the shape memory layer 3112 will be Fig.14 The deformed shape shown in (b) is oriented as shown in Fig.14 In the process of recovery, the shape memory layer 3112 will exert a restraining force on the bare battery cell 312, and the direction of the restraining force applied can be as follows: Fig.14 The direction of the arrow shown in (c).

[0127] In other embodiments, a single shape memory film (such as the first shape memory film 31121 or the second shape memory film 31122) and a single shell (such as the first shell or the second shell) can also be used to manufacture the obtained battery cell 31. Taking the single shape memory film as the first shape memory film 31121 and the single shell as the first shell as an example, the first shell and the first shape memory film 31121 can be stacked together for punching, so that the first shell and the first shape memory film 31121 are deformed. The deformed first shape memory film 31121 has two pits set at intervals, and the deformed first shell also has two pits set at intervals.

[0128] Since the shape memory layer 3112 can be located on the inner side of the shell body 3111, after the first shell and the first shape memory film 31121 are punched to form two spaced pits, the bare cell 312 can be placed in any pit corresponding to the first shape memory film 31121. Then, the first shape memory film 31121 and the first shell are folded in half, so that another pit corresponding to the first shape memory film 31121 and another pit corresponding to the first shell are sequentially covered on the bare cell 312. For example, if the first shell is an aluminum-plastic film and the inner layer of the aluminum-plastic film is a polypropylene layer, the polypropylene layer can be melted by heating for bonding, so that the folded first shape memory film 31121 forms the shape memory layer 3112, and the folded first shell forms the shell body 3111.

[0129] For example, Fig.15 This is a schematic diagram of the fourth shape memory layer provided in the embodiment of the present application before and after the pitting deformation. Fig.15 As shown, the shape memory layer 3112 may include a first shape memory film 31121 and a second shape memory film 31122 , and the shape memory layer 3112 is manufactured by the first shape memory film 31121 and the second shape memory film 31122 .

[0130] like Fig.15 As shown in (a), the initial shape of the first shape memory film 31121 is a shape corresponding to a pit with a depth of h1 / 2, and the initial shape of the second shape memory film 31122 is also a shape corresponding to a pit with a depth of h1 / 2.

[0131] During the manufacturing process of the battery cell 31, the housing body 3111 may also include a first housing (not shown). Fig.15 ) and a second housing (not shown in Fig.15 As shown in the figure, the first shell and the first shape memory film 31121 can be stacked together and punched, so that the first shell and the first shape memory film 31121 are deformed, and the second shell and the second shape memory film 31122 can be stacked together and punched, so that the second shell and the second shape memory film 31122 are deformed.

[0132] like Fig.15As shown in (b), the deformed first shape memory film 31121 has a pit, and the deformed first shell also has a pit. The pit corresponding to the first shell is consistent with the pit corresponding to the first shape memory film 31121 in shape and depression direction, and the pit corresponding to the first shell is stacked with the pit corresponding to the first shape memory film 31121. In addition, the deformed second shape memory film 31122 has a pit, and the deformed second shell also has a pit. The pit corresponding to the second shell is consistent with the pit corresponding to the second shape memory film 31122 in shape and depression direction, and the pit corresponding to the second shell is also stacked with the pit corresponding to the second shape memory film 31122.

[0133] Since the shape memory layer 3112 can be located on the inner side of the shell body 3111, after the first shell and the first shape memory film 31121, and the second shell and the second shape memory film 31122 are punched to form pits, the bare battery cell 312 can be placed in the pit corresponding to the first shape memory film 31121 or the second shape memory film 31122.

[0134] Taking the bare cell 312 placed in the pit corresponding to the second shape memory film 31122 as an example, the first shape memory film 31121 and the first shell can be sequentially covered on the bare cell 312, and the pit corresponding to the first shape memory film 31121 is arranged opposite to the pit corresponding to the second shape memory film 31122. Taking the first shell and the second shell as an example, both of which are aluminum-plastic films, and the inner layer of the aluminum-plastic film is a polypropylene layer, the polypropylene layer can be melted by heating for bonding, so that the first shape memory film 31121 and the second shape memory film 31122 form a shape memory layer 3112, and the first shell and the second shell form a shell body 3111. Fig.15 Reference numeral 40 shown in (b) indicates a position where the polypropylene layer is melt-bonded.

[0135] Since the shape memory layer 3112 is made by the first shape memory film 31121 and the second shape memory film 31122, the initial shape of the shape memory layer 3112 includes a shape corresponding to the pit having the first depth h1, and the deformed shape of the shape memory layer 3112 includes a shape corresponding to the pit having the second depth h2. Specifically, after the first shape memory film 31121 and the second shape memory film 31122 are punched, the sum of the depth of the pit formed by the first shape memory film 31121 and the depth of the pit formed by the second shape memory film 31122 is equal to the second depth h2.

[0136] At this time, the pit corresponding to the first shape memory film 31121 is recessed in the direction from the second shape memory film 31122 to the first shape memory film 31121 , and the pit corresponding to the second shape memory film 31122 is recessed in the direction from the first shape memory film 31121 to the second shape memory film 31122 .

[0137] like Fig.15 As shown in (c) in FIG. 1 , after the battery cell 31 is placed in the electronic device, during the charging and discharging process of the electronic device, that is, under normal working conditions, the shape memory layer 3112 will be Fig.15 The deformed shape shown in (b) is oriented as shown in Fig.15 In the process of recovery, the shape memory layer 3112 will exert a restraining force on the bare battery cell 312, and the direction of the restraining force applied can be as follows: Fig.15 The direction of the arrow shown in (c).

[0138] It should be noted that a single shape memory film and a single shell can also be used for punching processing to form two spaced-apart pits, and the bare battery cell 312 can be placed in any one of the pits of the shape memory film. Then, the shape memory film and the shell can be folded in half so that the other pit of the shape memory film and the other pit of the shell are sequentially covered on the bare battery cell 312.

[0139] Understandably, Fig.15 The initial shape of the shape memory layer 3112 in the embodiment is the shape corresponding to the pit having the first depth h1, relative to Fig.14 In the manner that the initial shape of the shape memory layer 3112 is planar, Fig.15 The restraining force exerted by the shape memory layer 3112 on the bare battery cell 312 will be less than Fig.14 The shape memory layer 3112 in the structure exerts a binding force on the bare battery cell 312.

[0140] In summary, combined Fig.14 and Fig.15 Correspondingly, the shape memory layer 3112 may include a first shape memory portion and a second shape memory portion connected to each other. The first shape memory portion is a first shape memory film 31121, and the second shape memory portion is a second shape memory film 31122; or, the first shape memory portion and the second shape memory portion are formed by folding the same shape memory film (such as the first shape memory film 31121 or the second shape memory film 31122) in half.

[0141] Among them, both the first shape memory part and the second shape memory part have pits, the pit corresponding to the first shape memory part is recessed in the direction from the second shape memory part to the first shape memory part, and the pit corresponding to the second shape memory part is recessed in the direction from the first shape memory part to the second shape memory part; and the pit corresponding to the first shape memory part and the pit corresponding to the second shape memory part are used together to form a accommodating cavity, which is used to accommodate the bare battery cell 312.

[0142] It should be noted that Figures 12 to 15 Only the specific structure composition and formation process of the shape memory layer 3112 are shown, and the specific structure composition and formation process of the shell body 3111 are not shown. The specific structure composition and formation process of the shell body 3111 can be referred to above. Figures 12 to 15 The corresponding text description.

[0143] For example, Figure 7 This is a cross-sectional schematic diagram of the second battery cell provided in the embodiment of the present application. Figure 7 As shown, the battery cell shell 311 includes a shell body 3111, a shape memory layer 3112 and an anti-corrosion layer 3113, and the anti-corrosion layer 3113 is located between the shape memory layer 3112 and the bare battery cell 312, that is, the anti-corrosion layer 3113 is located on the side of the shape memory layer 3112 close to the bare battery cell 312.

[0144] Among them, the material of the anti-corrosion layer 3113 can be a polymer material, such as at least one of polypropylene (PP), polyethylene terephthalate (PET), polyvinychloride (PVC), polyethylene (PE) and polyimide (PI).

[0145] By providing an anti-corrosion layer 3113 between the shape memory layer 3112 and the bare battery cell 312 , the shape memory layer 3112 can be prevented from being corroded by the electrolyte.

[0146] It should be noted that Figure 7 The battery cell 31 shown is Figure 6 The difference between the battery cell 31 shown is that Figure 7 In the battery cell 31 shown, an anti-corrosion layer 3113 is added between the shape memory layer 3112 and the bare battery cell 312. Figure 7 The remaining structures in the battery cell 31 shown are similar to those in FIG. Figure 6 The rest of the structure of the battery cell 31 is the same as that of the battery cell 31 shown. Figure 6 The corresponding description will not be repeated here to avoid repetition.

[0147] For example, Figure 8 This is a cross-sectional schematic diagram of a third type of battery cell provided in an embodiment of the present application. Figure 8 As shown, the battery cell housing 311 includes a housing body 3111 and a shape memory layer 3112 .

[0148] In some embodiments, the shell body 3111 includes a composite film, which includes a first film layer 31111, a second film layer 31112 and a third film layer 31113 stacked in sequence, and the first film layer 31111, the second film layer 31112 and the third film layer 31113 are arranged in sequence close to the bare battery cell 312.

[0149] like Figure 8 As shown, the shape memory layer 3112 is located on the side of the first film layer 31111 away from the bare battery core 312. In this way, the shape memory layer 3112 can be used as an outer wrapping layer of the bare battery core 312, and is located on the side of the composite film away from the bare battery core 312.

[0150] It should be noted that Figure 8 The battery cell 31 shown is Figure 6 The difference between the battery cell 31 shown is that Figure 8 The shape memory layer 3112 in the battery cell 31 shown is located on the side of the first film layer 31111 away from the bare battery cell 312, and Figure 6 The shape memory layer 3112 in the battery cell 31 shown is located on the side of the third film layer 31113 close to the bare battery cell 312. In addition, Figure 8 The remaining structures in the battery cell 31 shown are similar to those in FIG. Figure 6 The rest of the structure of the battery cell 31 shown is the same. For a detailed description of the housing body 3111 and the shape memory layer 3112, please refer to Figure 6 The corresponding description will not be repeated here to avoid repetition.

[0151] For example, Fig. 9 This is a cross-sectional schematic diagram of the fourth battery cell provided in the embodiment of the present application. Fig. 9 As shown, the battery cell housing 311 includes a housing body 3111 and a shape memory layer 3112 .

[0152] In some embodiments, the shell body 3111 includes a composite film, which includes a first film layer 31111, a second film layer 31112 and a third film layer 31113 stacked in sequence, and the first film layer 31111, the second film layer 31112 and the third film layer 31113 are arranged in sequence close to the bare battery cell 312.

[0153] like Fig. 9 As shown, the shape memory layer 3112 is located between the second film layer 31112 and the third film layer 31113. In this way, the shape memory layer 3112 can be used as an interlayer of the composite film.

[0154] Exemplarily, the composite film may be an aluminum-plastic film, the second film layer 31112 in the aluminum-plastic film is an aluminum layer, the first film layer 31111 in the aluminum-plastic film may be a nylon layer, the third film layer 31113 in the aluminum-plastic film may be a polypropylene layer, and the shape memory layer 3112 is located between the aluminum layer and the polypropylene layer.

[0155] Since the second film layer 31112 is used to block moisture, the embodiment of the present application sets the shape memory layer 3112 between the second film layer 31112 and the third film layer 31113, and the second film layer 31112 can block moisture to prevent moisture from oxidizing and corroding the shape memory layer 3112. If the shape memory layer 3112 is set between the first film layer 31111 and the second film layer 31112, the second film layer 31112 cannot block moisture from the shape memory layer 3112, and moisture from the outside will cause oxidation and corrosion to the shape memory layer 3112.

[0156] In addition, in the embodiment of the present application, the shape memory layer 3112 is disposed between the second film layer 31112 and the third film layer 31113 , and the third film layer 31113 can also prevent the shape memory layer 3112 from being corroded by the electrolyte.

[0157] It should be noted that Fig. 9 The battery cell 31 shown is Figure 6 The difference between the battery cell 31 shown is that Fig. 9 The shape memory layer 3112 in the battery cell 31 shown is located between the second film layer 31112 and the third film layer 31113, and Figure 6 The shape memory layer 3112 in the battery cell 31 shown is located on the side of the third film layer 31113 close to the bare battery cell 312. In addition, Fig. 9 The remaining structures in the battery cell 31 shown are similar to those in FIG. Figure 6 The rest of the structure of the battery cell 31 shown is the same. For a detailed description of the housing body 3111 and the shape memory layer 3112, please refer to Figure 6 The corresponding description will not be repeated here to avoid repetition.

[0158] For example, Fig.10 This is a cross-sectional schematic diagram of the fifth battery cell provided in the embodiment of the present application. Fig.10 As shown, the battery cell housing 311 includes a housing body 3111 and a shape memory layer 3112 .

[0159] In some embodiments, the housing body 3111 includes a metal housing. The material of the metal housing includes a metal material or a metal alloy material, the metal may be copper, iron, aluminum or the like, and the metal alloy material may be steel or aluminum alloy or the like.

[0160] For example, if the material of the metal shell is aluminum, the metal shell can also be called an aluminum shell; or, if the material of the metal shell is steel, the metal shell can also be called a steel shell, and further, the steel shell can be a stainless steel shell.

[0161] like Fig.10 As shown, the shape memory layer 3112 is located on one side of the metal shell close to the bare battery core 312. In this way, the shape memory layer 3112 can be used as an inner wrapping layer of the bare battery core 312.

[0162] It should be noted that Fig.10 The battery cell 31 shown is Figure 6 The difference between the battery cell 31 shown is that Fig.10 The shell body 3111 of the battery cell 31 shown is a metal shell. Figure 6 The shell body 3111 in the battery cell 31 shown is a composite film. In addition, Fig.10 The remaining structures in the battery cell 31 shown are similar to those in FIG. Figure 6 The rest of the structure of the battery cell 31 shown is the same. For a detailed description of the shape memory layer 3112, please refer to Figure 6 The corresponding description will not be repeated here to avoid repetition.

[0163] For example, Fig.11 This is a cross-sectional schematic diagram of the sixth battery cell provided in the embodiment of the present application. Fig.11 As shown, the battery cell shell 311 includes a shell body 3111, a shape memory layer 3112 and an anti-corrosion layer 3113, and the anti-corrosion layer 3113 is located between the shape memory layer 3112 and the bare battery cell 312, that is, the anti-corrosion layer 3113 is located on the side of the shape memory layer 3112 close to the bare battery cell 312.

[0164] By providing an anti-corrosion layer 3113 between the shape memory layer 3112 and the bare battery cell 312 , the shape memory layer 3112 can be prevented from being corroded by the electrolyte.

[0165] It should be noted that Fig.11 The battery cell 31 shown is Fig.10 The difference between the battery cell 31 shown is that Fig.11 In the battery cell 31 shown, an anti-corrosion layer 3113 is added between the shape memory layer 3112 and the bare battery cell 312. Fig.11 The remaining structures in the battery cell 31 shown are similar to those in FIG. Fig.10 The remaining structures of the battery cell 31 shown are the same.

[0166] In summary, the shape memory layer 3112 can be located on any side of the shell body 3111 or sandwiched between the film layers included in the shell body 3111. Figure 6 , Figure 7 , Fig.10 and Fig.11 As shown, the shape memory layer 3112 is located on one side of the housing body 3111 close to the bare battery core 312. Figure 8 As shown, the shape memory layer 3112 is located on the side of the housing body 3111 away from the bare battery core 312. Fig. 9 As shown, the shell body 3111 includes a composite film, which includes a first film layer 31111, a second film layer 31112 and a third film layer 31113 stacked in sequence, and the shape memory layer 3112 is sandwiched between the second film layer 31112 and the third film layer 31113.

[0167] Among them, the shape memory layer 3112 has an initial shape and a deformed shape. The initial shape is the memory shape restored when the temperature of the shape memory layer 3112 drops below the low-temperature phase memory temperature; the shape memory layer 3112 is used to apply a binding force to the bare battery cell 312 during the process of recovering from the deformed shape to the initial shape.

[0168] The bare cell may include a negative electrode active material, which includes but is not limited to a silicon-based material. Therefore, the negative electrode active material may be a silicon-based material or other materials with a high full charge expansion rate.

[0169] Taking the negative electrode active material as a silicon-based material as an example, the embodiment of the present application sets a shape memory layer 3112 in the battery cell housing 311, and utilizes the shape memory characteristics of the shape memory layer 3112. It can apply a restraining force to the bare battery cell 312 during the process of recovering from the deformed shape to the initial shape, so as to slow down the volume deformation of the silicon-based material, thereby suppressing the expansion of the battery cell and improving the problem of excessive expansion thickness of the battery cell; and it can also make the contact of the silicon-based material closer to suppress the increase of the porosity of the negative electrode sheet, reduce the possibility of pulverization of the silicon-based material or falling off the negative electrode current collector, ensure the transmission path of lithium ions, and thus reduce the decay rate of the battery cell capacity.

[0170] In the embodiment of the present application, the shape memory layer 3112 may include a one-way shape memory layer or a two-way shape memory layer. Furthermore, the shape memory layer 3112 may be a temperature-controlled shape memory layer, which may change shape under the control of temperature.

[0171] Specifically, the one-way shape memory layer may be a low-temperature shape memory layer having a low-temperature phase memory shape. After the low-temperature shape memory layer is deformed under the action of an external load, if the low-temperature shape memory layer is cooled so that the temperature of the low-temperature shape memory layer decreases to below the low-temperature phase memory temperature, the shape of the low-temperature shape memory layer will be restored to the low-temperature phase memory shape.

[0172] Taking the shape memory layer 3112 as a low-temperature shape memory layer as an example, the low-temperature phase memory shape is the initial shape in the embodiment of the present application. The low-temperature shape memory layer is heat-treated and trained so that when the temperature of the low-temperature shape memory layer is reduced to below the low-temperature phase memory temperature T1°C, that is, when the temperature of the low-temperature shape memory layer is ≤T1°C, the shape of the low-temperature shape memory layer is fixed to the initial shape. Fig.12 and Fig.14 As shown, the initial shape of the shape memory layer 3112 is planar; or, as Fig.13 and Fig.15 As shown, the initial shape of the shape memory layer 3112 is a shape corresponding to a pit having a first depth h1.

[0173] The two-way shape memory layer has two memory shapes, a high-temperature phase memory shape and a low-temperature phase memory shape. After the two-way shape memory layer is deformed under the action of an external load, if its temperature is changed, when the two-way shape memory layer is heated so that the temperature of the two-way shape memory layer is raised to above the high-temperature phase memory temperature, the shape of the two-way shape memory layer will be restored to the high-temperature phase memory shape; when the two-way shape memory layer is cooled so that the temperature of the two-way shape memory layer is reduced to below the low-temperature phase memory temperature, the shape of the two-way shape memory layer will be restored to the low-temperature phase memory shape.

[0174] Taking the shape memory layer 3112 as a two-way shape memory layer as an example, the low-temperature phase memory shape is the initial shape in the embodiment of the present application, the high-temperature phase memory shape can be the deformed shape in the embodiment of the present application, and the high-temperature phase memory shape can also be any other shape.

[0175] The two-way shape memory layer is heat-treated and trained so that when the temperature of the two-way shape memory layer drops below the low-temperature phase memory temperature T1°C, that is, when the temperature of the two-way shape memory layer is ≤ T1°C, the shape of the two-way shape memory layer is fixed to the initial shape. Fig.12 and Fig.14 As shown, the initial shape of the shape memory layer 3112 is planar; or, as Fig.13 and Fig.15 As shown, the initial shape of the shape memory layer 3112 is a shape corresponding to a pit having a first depth h1.

[0176] The two-way shape memory layer is subjected to heat treatment training, so that when the temperature of the two-way shape memory layer rises to above the high-temperature phase memory temperature T2°C, that is, when the temperature of the two-way shape memory layer is ≥ T2°C, the shape of the two-way shape memory layer is not limited, or the shape of the two-way shape memory layer is a shape corresponding to the pit with the second depth h2. In other words, the high-temperature phase memory shape of the two-way shape memory layer is not limited, or is a shape corresponding to the pit with the second depth h2.

[0177] The second depth h2 is greater than the first depth h1 , the first depth h1 is a value greater than 0, and the second depth h2 is less than the thickness of the battery cell 31 .

[0178] For example, the high temperature phase memory shape of the shape memory layer 3112 may be as follows: Figures 12 to 15 The deformed shape shown is actually a shape corresponding to a pit having a second depth h2.

[0179] Therefore, when the shape memory layer 3112 is a two-way shape memory layer, the shape memory layer 3112 also has a high-temperature phase memory shape, which is a memory shape restored when the temperature of the shape memory layer 3112 rises to above the high-temperature phase memory temperature T2° C. The high-temperature phase memory temperature T2 is greater than or equal to the low-temperature phase memory temperature T1, and the high-temperature phase memory shape of the shape memory layer 3112 and the deformed shape of the shape memory layer 3112 may be the same.

[0180] In some embodiments, the low temperature phase memory temperature T1 may be greater than or equal to 20°C, and the high temperature phase memory temperature T2 may be less than or equal to 100°C.

[0181] In this way, in the embodiment of the present application, the shape memory layer 3112 is deformed during the punching and forming process, and the shape memory layer 3112 is changed into a deformed shape; and, during the hot pressing and forming process, the shape memory layer 3112 can be further made to maintain the deformed shape. After the manufactured battery cell 31 is placed in an electronic device, during the charging and discharging process of the electronic device, that is, under normal operating conditions, the temperature of the shape memory layer 3112 may drop below the low temperature phase memory temperature T1°C, and the shape memory layer 3112 will recover from the deformed shape to the initial shape to apply a restraining force to the bare battery cell 312.

[0182] It should be noted that, during the process of the shape memory layer 3112 in the battery cell 31 recovering from the deformed shape to the initial shape, the shape memory layer 3112 is actually unable to completely recover to the initial shape due to the obstruction of the bare battery cell 312 itself.

[0183] In some embodiments, the material of the shape memory layer 3112 includes a shape memory alloy, and the shape memory alloy includes any one of a nickel-titanium alloy, a copper-nickel alloy, a copper-titanium alloy, a copper-aluminum alloy, a copper-zinc alloy, and an iron alloy.

[0184] In practical applications, the shape memory layer 3112 may be controlled to achieve different deformation degrees by selecting a combination of different shape memory alloy systems and / or changing the proportion of metal components of the same system.

[0185] In some embodiments, the thickness of the shape memory layer 3112 is 5 micrometers to 50 micrometers. For example, the thickness of the shape memory layer 3112 can be 10 micrometers, 20 micrometers, or 30 micrometers.

[0186] In some embodiments, the shape memory layer 3112 is a film layer without hollow regions. Thus, the shape memory layer 3112 in the battery cell 31 is a complete film layer without hollow regions.

[0187] In other embodiments, the shape memory layer 3112 is a film layer with hollow areas, and the hollow areas divide the shape memory layer 3112 into a preset pattern. The preset pattern includes one or more of a grid pattern, a Chinese-shaped pattern, a cross pattern, a well pattern, and a rice-shaped pattern.

[0188] In this way, the shape memory layer 3112 in the battery cell 31 has one or more hollow regions, so that the shape memory layer 3112 has a specific shape. If the shape memory layer 3112 is a film layer with hollow regions, it can reduce the material used for the shape memory layer 3112, thereby reducing the manufacturing cost of the battery cell 31.

[0189] The embodiment of the present application can evaluate and test the cycle performance of the battery cell, the porosity of the negative electrode sheet, and the thickness expansion rate of the battery cell by determining whether a binding force is applied to the bare battery cell. The test results are shown in Table 1 below.

[0190]

[0191] Table 1

[0192] Among them, for the battery sample with binding force applied (whose negative electrode active material can be silicon-based material), the battery capacity is reduced to 82% of the initial capacity when the number of charge and discharge times reaches 700 times (i.e. 700cls), while for the battery sample without binding force applied (whose negative electrode active material can be silicon-based material), the battery capacity is reduced to 65% of the initial capacity when the number of charge and discharge times reaches 700 times. It can be known that the cycle performance of the battery when the binding force is applied to the battery sample is better than the cycle performance of the battery when the binding force is not applied to the battery sample. Therefore, the embodiment of the present application can improve the cycle performance of the battery by applying a binding force to the bare battery.

[0193] Moreover, for the cell sample with restraining force applied, the porosity of the negative electrode sheet is 48.2% when the number of charge and discharge times reaches 700 times, while for the cell sample without restraining force applied, the porosity of the negative electrode sheet is 55.4% when the number of charge and discharge times reaches 700 times. It can be known that the porosity of the negative electrode sheet when restraining force is applied to the cell sample is lower than the porosity of the negative electrode sheet when restraining force is not applied to the cell sample. Therefore, the embodiment of the present application can suppress the increase of the porosity of the negative electrode sheet by applying restraining force to the bare cell.

[0194] In addition, for the battery sample with restraining force applied, the thickness expansion rate is 0 when the number of charge and discharge is 0, the thickness expansion rate is 3.1% when the number of charge and discharge is 1, the thickness expansion rate is 3.6% when the number of charge and discharge reaches 100, the thickness expansion rate is 5.5% when the number of charge and discharge reaches 300, the thickness expansion rate is 7.4% when the number of charge and discharge reaches 500, and the thickness expansion rate is 9.8% when the number of charge and discharge reaches 700. For the battery sample without restraining force applied, the thickness expansion rate is 0 when the number of charge and discharge is 0, the thickness expansion rate is 5.7% when the number of charge and discharge is 1, the thickness expansion rate is 10.6% when the number of charge and discharge reaches 100, the thickness expansion rate is 13.1% when the number of charge and discharge reaches 300, the thickness expansion rate is 16.5% when the number of charge and discharge reaches 500, and the thickness expansion rate is 19.6% when the number of charge and discharge reaches 700. It can be seen that under the same number of charge and discharge times, the thickness expansion rate when the restraining force is applied to the battery sample is lower than the thickness expansion rate when the restraining force is not applied to the battery sample. Therefore, the embodiment of the present application can suppress the expansion of the battery by applying a restraining force to the bare battery.

[0195] The embodiments of the present application can also simulate and test the expansion rate of the battery cell by using shape memory layers of different materials, shape memory layers of different thicknesses, shape memory layers with different low-temperature phase memory temperatures, shape memory layers with different pit depths in initial shapes, shape memory layers at different positions, and shape memory layers with different pit depths in deformed shapes. The test results are shown in Table 2 below.

[0196]

[0197] Table 2

[0198] Among them, in the battery cell corresponding to Example 1, the material of its shape memory layer is nickel-titanium alloy (Ni-Ti), the thickness of the shape memory layer is 10 microns, the low-temperature phase memory temperature of the shape memory layer is 25°C, the initial shape of the shape memory layer has a pit depth of 2 mm, the shape memory layer is located in the aluminum-plastic film sandwich (that is, located between the aluminum layer and the polypropylene layer), the battery cell is formed at a temperature of 80°C in the hot pressing process, and the deformed shape of the shape memory layer has a pit depth of 4 mm. For the battery cell corresponding to Example 1, its thickness expansion rate is 8% when the number of charge and discharge times reaches 300 times (that is, 300cls).

[0199] In the battery cell corresponding to Example 2, the material of its shape memory layer is copper-titanium alloy (Cu-Ti), the thickness of the shape memory layer is 10 microns, the low-temperature phase memory temperature of the shape memory layer is 25°C, the initial shape of the shape memory layer has a pit depth of 2 mm, the shape memory layer is located in the aluminum-plastic film sandwich (i.e., between the aluminum layer and the polypropylene layer), the battery cell is formed at a temperature of 80°C in the hot pressing process, and the deformed shape of the shape memory layer has a pit depth of 4 mm. For the battery cell corresponding to Example 2, its thickness expansion rate is 8% when the number of charge and discharge times reaches 300 times.

[0200] In the battery cell corresponding to Example 3, the material of its shape memory layer is nickel-titanium alloy, the thickness of the shape memory layer is 30 microns, the low-temperature phase memory temperature of the shape memory layer is 25°C, the initial shape of the shape memory layer has a pit depth of 2 mm, the shape memory layer is located in the aluminum-plastic film sandwich (i.e., between the aluminum layer and the polypropylene layer), the battery cell is formed at a temperature of 80°C in the hot pressing process, and the deformed shape of the shape memory layer has a pit depth of 4 mm. For the battery cell corresponding to Example 3, its thickness expansion rate is 6% when the number of charge and discharge times reaches 300 times.

[0201] In the battery cell corresponding to Example 4, the material of its shape memory layer is nickel-titanium alloy, the thickness of the shape memory layer is 10 microns, the low-temperature phase memory temperature of the shape memory layer is 35°C, the initial shape of the shape memory layer has a pit depth of 3 mm, the shape memory layer is located in the aluminum-plastic film sandwich (i.e., between the aluminum layer and the polypropylene layer), the battery cell is formed at a temperature of 80°C in the hot pressing process, and the deformed shape of the shape memory layer has a pit depth of 6 mm. For the battery cell corresponding to Example 4, its thickness expansion rate is 10% when the number of charge and discharge times reaches 300 times.

[0202] In the battery cell corresponding to Example 5, the material of its shape memory layer is nickel-titanium alloy, the thickness of the shape memory layer is 10 microns, the low-temperature phase memory temperature of the shape memory layer is 35°C, the initial shape of the shape memory layer has a pit depth of 2 mm, the shape memory layer is located in the inner layer of the aluminum-plastic film (i.e., located on the side of the aluminum-plastic film close to the bare battery cell), the battery cell is formed at a temperature of 80°C in the hot pressing process, and the deformed shape of the shape memory layer has a pit depth of 4 mm. For the battery cell corresponding to Example 5, its thickness expansion rate is 6% when the number of charge and discharge times reaches 300 times.

[0203] In the battery cell corresponding to Example 6, the material of its shape memory layer is nickel-titanium alloy, the thickness of the shape memory layer is 10 microns, the low-temperature phase memory temperature of the shape memory layer is 35°C, the initial shape of the shape memory layer has a pit depth of 2 mm, the shape memory layer is located on the outer layer of the aluminum-plastic film (i.e., on the side of the aluminum-plastic film away from the bare battery cell), the battery cell is formed at a temperature of 80°C in the hot pressing process, and the deformed shape of the shape memory layer has a pit depth of 4 mm. For the battery cell corresponding to Example 6, its thickness expansion rate is 8% when the number of charge and discharge times reaches 300 times.

[0204] Therefore, the embodiments of the present application can exert a restraining force on the bare battery cell through the shape memory layer to inhibit the expansion of the battery cell by reasonably selecting the material of the shape memory layer, the thickness of the shape memory layer, the low-temperature phase memory temperature of the shape memory layer, the pit depth of the initial shape of the shape memory layer, the position of the shape memory layer, and the pit depth of the deformed shape of the shape memory layer.

[0205] The above specific implementation methods further illustrate the purpose, technical solutions and beneficial effects of the present application in detail. It should be understood that the above are only specific implementation methods of the present application and are not used to limit the protection scope of the present application. Any modifications, equivalent substitutions, improvements, etc. made on the basis of the technical solutions of the present application should be included in the protection scope of the present application.

Claims

1. A battery cell, characterized in that: include: A battery cell shell, the battery cell shell comprising a shell body and a shape memory layer, wherein the shape memory layer is sandwiched between film layers included in the shell body; A bare battery cell, located in the battery cell housing; Among them, the shape memory layer has an initial shape and a deformed shape, the initial shape is the memory shape restored when the temperature of the shape memory layer drops below the low-temperature phase memory temperature; the deformed shape is the memory shape restored when the temperature of the shape memory layer rises above the high-temperature phase memory temperature; during the charging and discharging process of the electronic device, when the temperature of the shape memory layer drops below the low-temperature phase memory temperature, the shape memory layer recovers from the deformed shape toward the initial shape to apply a binding force to the bare battery cell; the high-temperature phase memory temperature is greater than or equal to the low-temperature phase memory temperature; the low-temperature phase memory temperature is greater than or equal to 20°C, and the high-temperature phase memory temperature is less than or equal to 100°C.

2. The battery cell according to claim 1, characterized in that: The shell body includes a composite film, the composite film includes a first film layer, a second film layer and a third film layer stacked in sequence, and the first film layer, the second film layer and the third film layer are sequentially arranged close to the bare battery core; The material of the second film layer includes a metal material, and the first film layer, the second film layer and the third film layer are film layers made of different materials.

3. The battery cell according to claim 2, characterized in that: The shape memory layer is located on a side of the third film layer close to the bare battery core.

4. The battery cell according to claim 2, characterized in that: The shape memory layer is located on a side of the first film layer away from the bare battery core.

5. The battery cell according to claim 2, characterized in that: The shape memory layer is located between the second film layer and the third film layer.

6. The battery cell according to claim 1, characterized in that: The shell body comprises a metal shell, and the shape memory layer is located on a side of the metal shell close to the bare battery core.

7. The battery cell according to claim 3 or 6, characterized in that: The battery cell casing further includes an anti-corrosion layer, and the anti-corrosion layer is located between the shape memory layer and the bare battery cell.

8. The battery cell according to claim 1, characterized in that: The initial shape includes a plane or a shape corresponding to a pit with a first depth; the deformed shape includes a shape corresponding to a pit with a second depth, and the second depth is greater than the first depth.

9. The battery cell according to claim 8, characterized in that: The shape memory layer includes a first shape memory portion and a second shape memory portion connected to each other; Wherein, the first shape memory part has the pit, the pit is recessed in the direction from the second shape memory part to the first shape memory part, and the pit corresponding to the first shape memory part is used to form a receiving cavity, and the receiving cavity is used to receive the bare battery cell; Alternatively, the second shape memory portion has the pit, the pit is recessed in a direction from the first shape memory portion to the second shape memory portion, and the pit corresponding to the second shape memory portion is used to form a receiving cavity, and the receiving cavity is used to receive the bare battery cell; Alternatively, both the first shape memory portion and the second shape memory portion have the pit, the pit corresponding to the first shape memory portion is recessed in the direction from the second shape memory portion to the first shape memory portion, the pit corresponding to the second shape memory portion is recessed in the direction from the first shape memory portion to the second shape memory portion, and the pit corresponding to the first shape memory portion and the pit corresponding to the second shape memory portion are jointly used to form a accommodating cavity, and the accommodating cavity is used to accommodate the bare battery cell.

10. The battery cell according to claim 1, characterized in that: The shape memory layer is used to form the deformed shape during the punching and forming process of the battery cell shell; Alternatively, the shape memory layer is used to form the deformed shape during the punching and forming process of the battery cell shell and the hot pressing process of the battery cell.

11. The battery cell according to claim 1, characterized in that: The material of the shape memory layer includes a shape memory alloy, and the shape memory alloy includes any one of a nickel-titanium alloy, a copper-nickel alloy, a copper-titanium alloy, a copper-aluminum alloy, a copper-zinc alloy, and an iron alloy.

12. The battery cell according to claim 1, characterized in that: The shape memory layer has a thickness of 5 micrometers to 50 micrometers.

13. The battery cell according to claim 1, characterized in that: The shape memory layer is a film layer without a hollow area; Alternatively, the shape memory layer is a film layer having a hollow area, and the hollow area divides the shape memory layer into a preset pattern; the preset pattern includes one or more of a grid pattern, a U-shaped pattern, a cross pattern, a tic-tac-toe pattern, and a '-shaped' pattern.

14. The battery cell according to claim 1, characterized in that: The battery cell also includes an electrolyte, and the electrolyte is located in the battery cell housing; The bare battery cell includes a positive electrode sheet, a negative electrode sheet and a separator, wherein the separator is located between the positive electrode sheet and the negative electrode sheet; the positive electrode sheet includes a positive electrode collector and a positive electrode active material layer; the negative electrode sheet includes a negative electrode collector and a negative electrode active material layer, wherein the material of the negative electrode active material layer includes a silicon-based material.

15. A battery, characterized in that: It comprises a battery protection board and a battery cell as claimed in any one of claims 1 to 14, wherein the battery protection board is connected to the battery cell.

16. An electronic device, characterized in that: comprising a housing, a power management module, a charging management module and the battery as claimed in claim 15; Wherein, a battery compartment is provided in the shell, and the battery is located in the battery compartment; and the battery is connected to the power management module and the charging management module respectively.

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