Battery module, battery pack and electric device

Abstract

Disclosed in the present application are a battery module, a battery pack and an electric device. The battery module comprises a battery cell stack and a restraint assembly, wherein the cell stack comprises a plurality of battery cells and a piezoelectric expansion member; and the restraint assembly is wound around the battery cell stack along the circumference of the battery cell stack, such that the restraint assembly can provide over the entire circumference of the battery cell stack a restraint force acting on the battery cell stack, and thus the restraint force applied by the restraint assembly on the battery cell stack is greater. In this way, even if the expansion force of the battery cell stack is relatively great, the restraint assembly can still ensure interface requirements for battery cells in the battery cell stack. The piezoelectric expansion member may be energized and expand to press against the battery cells, thereby providing a restraint force acting on the battery cells.

Description

Battery modules, battery packs and electrical equipment

[0001] This application claims priority to Chinese Patent Application No. 202520538470.7, filed on March 25, 2025, entitled “Battery Module, Battery Pack and Electrical Equipment”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of battery technology, and more specifically, to a battery module, a battery pack, and an electrical device. Background Technology

[0003] During the cyclic charging and discharging process, the cells within the battery pack transition between low and high charge levels. Consequently, the internal chemical reactions within the cells cause them to expand or contract. The simultaneous expansion of multiple cells in the battery pack generates significant expansion forces. To ensure the interface requirements of the cells during charge-discharge cycles, an anti-expansion structure is needed to resist these expansion forces and reduce the degree of cell expansion deformation.

[0004] Currently, the anti-expansion structure of battery packs uses a structure in which a metal tension plate is connected to the end plate of the battery pack. This structure has relatively low restraint force and cannot meet the anti-expansion requirements of battery packs with large expansion forces. Summary of the Invention

[0005] The purpose of this application is to provide a battery module, battery pack, and electrical device to solve the problem of low restraint force in the current anti-expansion structure of battery packs.

[0006] In a first aspect, this application provides a battery module, including:

[0007] A battery cell stack includes a plurality of battery cells and a piezoelectric expander, wherein the plurality of battery cells and the piezoelectric expander are stacked along a first direction, and the piezoelectric expander is configured to expand upon being energized to compress the battery cells;

[0008] A restraint assembly is disposed around the cell stack in the circumferential direction.

[0009] In some embodiments, the first direction is the thickness direction of the battery cell.

[0010] In some embodiments, the piezoelectric expansion member forms a third orthographic projection on the cell in the first direction, the third orthographic projection being located within the cell.

[0011] In some embodiments, there are multiple piezoelectric expansion elements, and all of the multiple piezoelectric expansion elements are arranged along a first direction.

[0012] In some embodiments, the cell stack further includes a second electrical connector connected to a plurality of the piezoelectric expansion elements.

[0013] In some embodiments, the second electrical connector is also electrically connected to the battery cell, so that all of the plurality of piezoelectric expansion elements are electrically connected to the battery cell.

[0014] In some embodiments, the piezoelectric expansion member is disposed between at least a portion of the adjacent cells in a plurality of the battery cells.

[0015] In some embodiments, the piezoelectric expansion member is provided with a positive terminal connector and a negative terminal connector, and there are two second electrical connectors, with the positive terminal connector connected to one of the second electrical connectors and the negative terminal connector connected to the other second electrical connector.

[0016] In some embodiments, the positive and negative terminals are located at both ends of the piezoelectric expansion member along the second direction, and two second electrical connectors are also located at both ends of the piezoelectric expansion member along the second direction, the second direction intersecting the first direction.

[0017] In some embodiments, the restraint assembly forms a first orthographic projection on the surface of the cell stack, and the surface of the cell stack covers the first orthographic projection.

[0018] In some embodiments, the restraint assembly includes a plurality of restraint wires, which are spaced apart.

[0019] Alternatively, multiple restraint wires may be arranged adjacent to each other;

[0020] Alternatively, at least some of the multiple restraint wires may be stacked together.

[0021] In some embodiments, the restraint wire is a carbon fiber wire and / or a metal wire.

[0022] In some embodiments, the cross-sectional area of ​​the restraint assembly in the first direction satisfies: S1≥F / (2×Rm);

[0023] Wherein, S1 is the cross-sectional area of ​​the restraint assembly in the first direction, F is the preset restraint force acting on the battery cell stack, and Rm is the tensile strength of the restraint wire in the first direction.

[0024] In some embodiments, the cell stack further includes at least one end plate, which is stacked on the cell along the first direction, and the at least one end plate is located outside the outermost cell among the plurality of cells.

[0025] In some embodiments, the piezoelectric expansion member is disposed between the end plate and the adjacent battery cell.

[0026] In some embodiments, the end plate has an arc surface on the side opposite to the battery cell.

[0027] In some embodiments, the end plate includes an abutting portion and a winding portion, the abutting portion abutting against the battery cell, the two ends of the winding portion extending in the direction of extension being respectively connected to the abutting portion, and a cavity being formed between the winding portion and the abutting portion.

[0028] In some embodiments, the end plate further includes a support portion located in the cavity and connected to the abutment portion and the winding portion.

[0029] In some embodiments, the end plate forms a second orthographic projection on the cell along the first direction, and the second orthographic projection is covered by the cell.

[0030] In some embodiments, the second orthographic projection coincides with the battery cell.

[0031] In some embodiments, at least two end plates are located at both ends of the cell stack along the first direction, a plurality of cells are electrically connected, a plurality of cells are electrically connected to at least two end plates, and at least two end plates respectively form the positive terminal and the negative terminal of the cell stack.

[0032] In some embodiments, the cell stack further includes a first electrical connector connected to the plurality of cells and the two end plates.

[0033] In some embodiments, the first electrical connector includes a plurality of electrical connection portions, the electrical connection portions connecting adjacent battery cells, and the electrical connection portions connecting the end plate and adjacent battery cells.

[0034] In some embodiments, positive and negative connection portions are respectively provided on opposite sides of the two end plates, and the positive and negative connection portions are electrically connected to the corresponding end plates.

[0035] In some embodiments, the battery module further includes a positive electrode connection portion and a negative electrode connection portion, both of which are electrically connected to the battery cell. The positive electrode connection portion and the negative electrode connection portion respectively constitute the positive electrode connection end and the negative electrode connection end of the battery cell stack.

[0036] In some embodiments, the positive electrode connection is electrically connected to one of the outermost cells of the plurality of cells, and the negative electrode connection is electrically connected to another of the outermost cells of the plurality of cells.

[0037] Secondly, this application also provides a battery pack, including a tray and the battery module described above, wherein the tray has a battery cavity and the battery module is disposed within the battery cavity.

[0038] In some embodiments, along the first direction, the battery cavity has two opposing abutting inner walls, and the opposite sides of the restraint assembly abut against the two abutting inner walls respectively.

[0039] In some embodiments, the battery pack further includes a detection element and a control element, the detection element being electrically connected to the control element, and the control element being electrically connected to the piezoelectric expansion element;

[0040] The detection element is configured to detect the expansion of the battery cell, and the control element controls the degree of expansion of the piezoelectric expansion element according to the expansion of the battery cell.

[0041] In some embodiments, the detection element is configured to detect parameters of the battery cell, and the detection element determines the degree of expansion of the battery cell based on the parameters of the battery cell.

[0042] Thirdly, this application also provides an electrical device, including the battery module described above, or including the battery pack described above.

[0043] This application provides a battery module in which multiple battery cells are stacked along a first direction, resulting in a compact overall structure of the cell stack. A restraining component is wound around the cell stack circumferentially, providing restraining force in all circumferential directions, thus increasing the restraining force exerted by the restraining component on the cell stack. This ensures that even with significant expansion forces within the cell stack, the restraining component maintains the interface requirements of the cells. Simultaneously, a piezoelectric expander can expand upon electrical current to compress the cells, providing additional restraining force. The combined restraining forces from the restraining component and the piezoelectric expander work together to more effectively suppress the expansion tendency of the cells, resulting in a more stable cell structure.

[0044] In the battery pack provided in this application, the tray can be used to support and install the battery modules, and the tray can also protect the battery modules to a certain extent, so as to make the structure of the battery pack more stable.

[0045] The electrical equipment provided in this application, including the battery module or battery pack mentioned above, makes the electrical equipment safer and more reliable during operation. Attached Figure Description

[0046] Figure 1 is a schematic diagram of the battery module provided in an embodiment of this application;

[0047] Figure 2 is a schematic diagram of the restraint assembly of the battery module provided in an embodiment of this application;

[0048] Figure 3 is a magnified view of area A in Figure 2;

[0049] Figure 4 is a schematic diagram of the positive and negative terminals of the piezoelectric expansion component of the battery module provided in the embodiment of this application;

[0050] Figure 5 is a schematic diagram of the restraint wires of the battery module provided in the embodiment of this application;

[0051] Figure 6 is a schematic diagram of the piezoelectric expansion component of the battery module provided in the embodiment of this application disposed on the end plate;

[0052] Figure 7 is a schematic diagram of three piezoelectric expansion elements disposed on the end plate in the battery module provided in the embodiment of this application;

[0053] Figure 8 is a schematic diagram of the first electrical connector of the battery module provided in an embodiment of this application;

[0054] Figure 9 is a magnified view of area B in Figure 8;

[0055] Figure 10 is a schematic diagram of the positive electrode connection of the battery module provided in the embodiment of this application connected to the end plate;

[0056] Figure 11 is a schematic diagram of the positive electrode connection portion of the battery module provided in an embodiment of this application;

[0057] Figure 12 is a magnified view of region C in Figure 11;

[0058] Figure 13 is a schematic diagram of the battery pack provided in an embodiment of this application;

[0059] Figure 14 is a schematic diagram showing the connection between the control component and the detection component of the battery pack provided in an embodiment of this application;

[0060] Figure 15 is a schematic diagram of the electrical equipment provided in the embodiments of this application.

[0061] Reference numerals: 10-Battery module; 20-Battery pack; 30-Electrical device; 100-Cell stack; 110-Cell; 111-Taper; 120-End plate; 121-Abutting part; 122-Winding part; 123-Supporting part; 130-First electrical connector; 131-Electrical connection part; 140-Piezoelectric expansion element; 141-Positive connector; 142-Negative connector; 150-Positive connection part; 160-Negative connection part; 170-Second electrical connector; 200-Constraint assembly; 210-Constraint wire; 220-First restraint part; 230-Second restraint part; 300-Tray; 310-Battery cavity; 311-Inner wall support; 400-Detection element; 500-Control element. Detailed Implementation

[0062] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0063] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0064] During the cyclic charging and discharging process, the cells within the battery pack transition between low and high charge levels. Consequently, the internal chemical reactions within the cells cause them to expand or contract. The simultaneous expansion of multiple cells in the battery pack generates significant expansion forces. To ensure the interface requirements of the cells during charge-discharge cycles, an anti-expansion structure is needed to resist these expansion forces and reduce the degree of cell expansion deformation.

[0065] Currently, the anti-expansion structure of battery packs adopts a structure in which a metal pull plate is threadedly connected to the end plate of the battery pack. The restraining force of this structure is entirely provided by the connection between the pull plate and the end plate. However, the threaded connection between the pull plate and the end plate cannot provide a large restraining force, resulting in a small restraining force in this structure, which cannot meet the anti-expansion requirements of battery packs with large expansion forces.

[0066] To overcome the shortcomings of existing technologies, this application proposes a battery module in which multiple battery cells are stacked along a first direction, resulting in a compact overall structure of the cell stack. A restraint component is wound around the cell stack circumferentially, providing restraint forces in all circumferential directions, thus increasing the restraint force exerted on the cell stack. This ensures that even with significant expansion forces, the restraint component maintains the interface requirements of the cells within the stack. A piezoelectric expander expands upon energization, compressing the cell and providing restraint forces. The combined restraint forces from the restraint component and the piezoelectric expander work together to more effectively suppress cell expansion. The degree of expansion of the piezoelectric expander can be finely adjusted based on the voltage input, allowing for precise control of the restraint forces acting on the cell, resulting in a more stable cell structure and ultimately a stable battery module structure.

[0067] In the battery pack proposed in this application, the tray can be used to support and install the battery modules, and the tray can also protect the battery modules to a certain extent, so as to make the structure of the battery pack more stable.

[0068] The electrical equipment proposed in this application, including the battery module or battery pack mentioned above, makes the electrical equipment safer and more reliable during operation.

[0069] The contents of this application will now be described in detail with reference to the accompanying drawings, so that those skilled in the art can have a clearer and more detailed understanding of the contents of this application.

[0070] This application discloses a battery module, as shown in Figures 1 and 2, including a cell stack 100 and a restraint assembly 200. This battery module 10 can be applied to a battery pack or electrical device.

[0071] The cell stack 100 includes multiple cells 110, which can be stacked along a first direction, i.e., the X direction in Figure 1. This allows the multiple cells 110 to be arranged more centrally, making the structure of the cell stack 100 more compact. The multiple cells 110 increase the capacity of the cell stack 100, thereby increasing the capacity of the battery module 10 of this application.

[0072] The battery cell 110 has a tab 111 on one side. The tab 111 is a component that connects the battery cell 110 to an external electrical connection component. The tab 111 may include a positive tab and a negative tab, which can constitute the positive and negative terminals of the battery cell 110. Specifically, one end of the tab 111 extends into the interior of the battery cell 110, and the other end of the tab 111 extends into the exterior of the battery cell 110.

[0073] In this configuration, a tab 111 is provided on one side of the battery cell 110 along a second direction, which intersects with the first direction. The second direction is the Y direction in Figure 1. In this way, the battery cell 110 and the tab 111 can be distributed along the second direction, so that the tab 111 is located at the end of the battery cell 110. Correspondingly, when multiple battery cells 110 are stacked along the first direction, the tab 111 will not affect the stacking of multiple battery cells 110, making the structure of the battery cell stack 100 more compact.

[0074] The restraint component 200 is circumferentially wound around the cell stack 100 along the second direction, so that the restraint component 200 can be pressed onto the cell stack 100. The restraint component 200 can form a restraining force acting towards the cell stack 100. This restraining force can, to a certain extent, counteract the expansion force generated by the cell 110 during charging and discharging, so that the part of the cell stack 100 wound by the restraint component 200 is restricted within the restraint component 200, avoiding excessive deformation and expansion of the cell 110 in the cell stack 100, ensuring the interface requirements of the cell 110 during charging and discharging, and making the battery module 10 of this application more stable and reliable.

[0075] The restraint component 200 is wound around the cell stack 100, so that the restraint component 200 can provide restraint force on the cell stack 100 in the circumferential direction, thereby making the restraint force exerted by the restraint component 200 on the cell stack 100 greater. In this way, even if the expansion force of the cell stack 100 is large, the restraint component 200 can still ensure the interface requirements of the cells 110 in the cell stack 100.

[0076] Furthermore, since the restraint component 200 can be wound around the cell stack 100, the restraint component 200 is a deformable structural component. The restraint component 200 has a more sufficient and tighter contact with the cell stack 100, thereby making the restraint force of the restraint component 200 on the cell stack 100 greater, making the battery module 10 more stable and safer during charging and discharging.

[0077] Specifically, the circumferential direction of the second direction is perpendicular to the second direction in its plane, and the circumferential direction of the second direction is rotated around the second direction. By winding the restraint assembly 200 around the cell stack 100 along the circumferential direction of the second direction, the restraint assembly 200 can avoid the tab 111 on one side of the cell 110. In this way, when the restraint assembly 200 is set, the tab 111 will not interfere with the restraint assembly 200, and the restraint assembly 200 can fully contact and cooperate with the surface of the cell 110 in the circumferential direction of the second direction, so that the restraint force of the restraint assembly 200 on the cell stack 100 is more sufficient, making the battery module 10 more stable and safer during charging and discharging.

[0078] Specifically, the restraint assembly 200 forms a first orthographic projection on the surface of the cell stack 100 in the direction toward the cell stack 100. The first orthographic projection is the projection area formed by the portion of the restraint assembly 200 and the cell stack 100 opposite to each other. Correspondingly, the first orthographic projection can be distributed on the surface of each cell 110, with the first orthographic projection located on one side of the surface of the cell 110 and the tab 111 located on the other side of the surface of the cell 110. In this way, the first orthographic projection of the restraint assembly 200 and the tab 111 are located on different sides of the surface of the cell 110, so that the restraint assembly 200 and the tab 111 of the cell 110 have a certain distance between them, and the restraint assembly 200 and the tab 111 will not interfere with each other.

[0079] Specifically, when the restraint assembly 200 is wound around the cell stack 100, it does not obstruct or contact the tab 111, allowing the tab 111 to be exposed on the surface of the cell 110. The tab 111 can be easily connected to other electrical connection components, enabling the cell 110 to be charged or discharged to the outside. Correspondingly, the tab 111 does not affect the winding path of the restraint assembly 200, allowing the restraint assembly 200 to be fully wound around one side of the cell 110, resulting in more sufficient contact between the restraint assembly 200 and the cell stack 100. This leads to a greater restraining force exerted by the restraint assembly 200 on the cell stack 100, making the structure of the cell stack 100 more stable during charging and discharging.

[0080] In addition, when preparing the battery module 10 of this application, it is necessary to wind the restraint component 200 around the cell stack 100 so that the tab 111 will not interfere with the restraint component 200 being wound around the cell stack 100, thereby making it more convenient for the restraint component 200 to be wound around the cell stack 100.

[0081] Referring to Figures 2 and 3, the cell stack 100 also includes a piezoelectric expansion member 140, which can be stacked on the cell 110 along a first direction. By inputting a voltage to the piezoelectric expansion member 140, the piezoelectric expansion member 140 can expand to compress the cell 110, thereby providing a restraining force to the cell 110. Furthermore, by adjusting the magnitude of the voltage input to the piezoelectric expansion member 140, the magnitude of the compressing force exerted by the piezoelectric expansion member 140 on the cell 110 can be adjusted, thereby allowing for more precise adjustment of the restraining force acting on the cell 110.

[0082] When the battery cell 110 tends to expand during charging and discharging, its temperature will increase accordingly. The higher the temperature of the battery cell 110, the greater the heat generated, and the greater the expansion tendency of the battery cell 110. Accordingly, the expansion degree of the piezoelectric expansion element 140 can be increased by adjusting the voltage supplied to it. This results in a greater restraining force exerted by the piezoelectric expansion element 140 on the battery cell 110, thus better suppressing the expansion tendency of the battery cell 110.

[0083] When the temperature of the battery cell 110 is relatively low, the heat generated is smaller, and the expansion tendency of the battery cell 110 is relatively smaller. Correspondingly, the expansion degree of the piezoelectric expansion element 140 can be further reduced by adjusting the voltage supplied to it. In this way, the restraining force of the piezoelectric expansion element 140 on the battery cell 110 can be balanced with the expansion force of the battery cell 110, thereby better suppressing the expansion tendency of the battery cell 110. This avoids excessive restraining force exerted by the piezoelectric expansion element 140 on the battery cell 110, which could damage the battery cell 110, thus protecting the battery cell 110.

[0084] In this way, the magnitude of the restraining force on the cell 110 can be changed in real time according to the actual situation of the cell 110, so that the cell 110 is safer and more stable during the charging and discharging process, thereby making the battery module of this application safer and more stable during the charging and discharging process.

[0085] Specifically, the piezoelectric expansion element 140 can be made of piezoelectric materials, specifically piezoelectric ceramics.

[0086] In some embodiments, the first direction can be set as the thickness direction of the cell 110, wherein the thickness direction of the cell 110 is the X direction in Figure 1, and the cell 110 also has a length direction and a width direction. Multiple cells 110 can also be electrically connected, specifically in series, thus increasing the capacity of the battery module 10 of this application. It should be understood that the cell 110 can have a structure similar to a thin plate, making the length and width dimensions of the cell 110 larger than its thickness dimension. The ratio of the length, width, and thickness dimensions of the cell stack 100 formed by stacking multiple cells 110 along the thickness direction is smaller. This avoids the cell stack 100 being too large in a single direction, effectively reducing the ratio of the length, width, and thickness of the cell stack 100, thus making the structure of the cell stack 100 compact.

[0087] The second direction is perpendicular to the first direction, so that the direction from the tab 111 to the cell 110 is perpendicular to the first direction, that is, the direction from the tab 111 to the cell 110 is perpendicular to the thickness direction of the cell 110. Accordingly, the tab 111 is located on the surface of the cell 110 facing the surface perpendicular to the first direction.

[0088] It should be understood that among the various surfaces of the battery cell 110, the surface facing the same direction as the first direction is the large surface of the battery cell 110, and the area of ​​the large surface of the battery cell 110 is relatively larger than the area of ​​the other side surfaces of the battery cell 110. During the charging and discharging process, the expansion force of the battery cell 110 is mainly along the first direction, making the expansion tendency of the large surface the greatest. That is, the expansion of the battery cell 110 is mainly manifested in the expansion of the large surfaces on opposite sides of the battery cell 110 in opposite directions. Correspondingly, the overall expansion trend of the battery cell stack 100 is mainly formed along the positive and negative directions of the first direction.

[0089] In this application, the direction of the restraining force generated by the restraining component 200 on the cell stack 100 includes a first direction, so that the restraining force of the restraining component 200 on the cell stack 100 can suppress the tendency of the cell stack 100 to expand in both directions along the first direction, thereby suppressing the main expansion trend of the cell stack 100, so that the cell stack 100 can have better structural stability in the first direction.

[0090] Furthermore, it should be understood that, since the restraint assembly 200 is wound around the cell stack 100, the restraint assembly 200 can also exert a force on the cell stack 100 in a direction simultaneously perpendicular to the first direction and the second direction. Specifically, the restraint assembly 200 can also be pressed onto the surface of the cell stack 100 that is perpendicular to the first direction and does not have tabs 111, thereby allowing the restraint assembly 200 to suppress the expansion deformation of the cell stack 100 in the direction perpendicular to the first direction.

[0091] In some embodiments, referring to FIG1, the number of piezoelectric expansion elements 140 in this application can be set to multiple, and the multiple piezoelectric expansion elements 140 are stacked along a first direction. At least two of the multiple piezoelectric expansion elements 140 are stacked, and these two piezoelectric expansion elements 140 can deliver different voltages, that is, some piezoelectric expansion elements 140 have a larger voltage and other piezoelectric expansion elements 140 have a smaller voltage. Of course, some piezoelectric expansion elements 140 can also deliver the same voltage.

[0092] Due to the different voltages of some piezoelectric expansion elements 140, the expansion degrees of each piezoelectric expansion element 140 differ. However, because the two stacked piezoelectric expansion elements 140 are interconnected, they cannot expand or contract freely; instead, they are mutually constrained. Due to this mutual constraint, the piezoelectric expansion element 140 with the higher voltage expands more, while the piezoelectric expansion element 140 with the lower voltage expands less. This difference in expansion causes the stacked piezoelectric expansion elements 140 to bend and deform in a direction perpendicular to the first direction. Specifically, the piezoelectric expansion element 140 with the higher voltage expands outward, causing the overall structure formed by the stacked piezoelectric expansion elements 140 to bend outward. The piezoelectric expansion element 140 with the lower voltage contracts inward, further exacerbating the outward bending tendency of the overall structure formed by the stacked piezoelectric expansion elements 140. The overall structure formed by the stacked piezoelectric expansion members 140 exerts a greater restraining force on the battery cell 110, thereby more effectively suppressing the expansion tendency of the battery cell 110 in the first direction.

[0093] In some embodiments, referring to FIG1, among the plurality of piezoelectric expansion elements 140 stacked sequentially along a first direction, the voltage of any one piezoelectric expansion element 140 is higher or lower than the voltage of the piezoelectric expansion elements 140 on opposite sides. That is, along the first direction, the voltage of the plurality of sequentially stacked piezoelectric expansion elements 140 alternates between increasing and decreasing. This allows for more precise bending deformation of the overall structure formed by the plurality of sequentially stacked piezoelectric expansion elements 140, thereby providing a more precise restraint force acting on the battery cell 110.

[0094] In some embodiments, referring to FIG1, the piezoelectric expansion member 140 of this application forms a third orthographic projection on the battery cell 110 along the first direction. The third orthographic projection is covered by the battery cell 110, that is, the third orthographic projection can be located within the large surface of the end side of the battery cell 110 in the first direction. In this way, the side of the piezoelectric expansion member 140 facing the battery cell 110 is in contact with the battery cell 110. Correspondingly, the battery cell 110 can be supported in the opposite direction on the side of the piezoelectric expansion member 140 facing the battery cell 110, making the structure of the piezoelectric expansion member 140 more stable. In addition, the material used for the piezoelectric expansion member 140 can be reduced, thereby reducing the manufacturing cost of the battery module 10 of this application.

[0095] In some embodiments, referring to FIG1, the piezoelectric expansion member 140 forms a third orthographic projection on the cell 110 along the first direction, which can coincide with the cell 110. In this way, the third orthographic projection can just cover the end of the cell 110 along the first direction, so that the piezoelectric expansion member 140 can fully cover the cell 110, so that the force generated by the piezoelectric expansion member 140 expanding when energized can fully act on each part of the large surface of the cell 110 in the first direction.

[0096] In addition, in other embodiments, the area of ​​the piezoelectric expansion member 140 forming the third orthographic projection on the cell 110 along the first direction can be set to be smaller than the area of ​​the end of the cell 110 in the first direction. This can save the material used for the piezoelectric expansion member 140, thereby reducing the cost of the battery module 10 of this application.

[0097] In some embodiments, referring to FIG3, the cell stack 100 of this application may further include a second electrical connector 170, which is connected to a plurality of piezoelectric expansion members 140 and can also be connected to a plurality of cell 110. Thus, the cell 110 can supply power to the piezoelectric expansion members 140 through the second electrical connector 170, allowing the piezoelectric expansion members 140 to expand and deform under current, thereby providing a restraining force to the cell 110. The second electrical connector 170 can be connected to a power distribution device, which can control the expansion degree of the piezoelectric expansion members 140 according to the expansion degree of the cell 110, so that the piezoelectric expansion members 140 can provide different magnitudes of restraining force.

[0098] In some embodiments, the second electrical connector 170 can be electrically connected to the battery cell 110. By providing the second electrical connector 170, multiple piezoelectric expansion members 140 can be electrically connected to the battery cell 110. In this way, multiple piezoelectric expansion members 140 do not need to be separately provided with a structure for being electrically connected to the battery cell 110, which can reduce the number of electrical connection parts 131 and simplify the structure of the battery module 10 of this application.

[0099] In some embodiments, referring to FIG4, the piezoelectric expansion member 140 of this application may further include a positive terminal connector 141 and a negative terminal connector 142. The positive terminal connector 141 and the negative terminal connector 142 are the positive and negative terminals of the piezoelectric expansion member 140, and the piezoelectric expansion member 140 is connected to the second electrical connector 170 through the positive terminal connector 141 and the negative terminal connector 142, thereby enabling the piezoelectric expansion member 140 to be connected to the second electrical connector 170.

[0100] In some embodiments, referring to FIG4, the positive electrode connector 141 and the negative electrode connector 142 of the piezoelectric expansion member 140 in this application may be disposed at both ends of the piezoelectric expansion member 140 along a second direction. The second direction is perpendicular to the first direction. Specifically, the piezoelectric expansion member 140 may also be a thin sheet structure, and the first direction is the thickness direction of the piezoelectric expansion member 140. By disposing the positive electrode connector 141 and the negative electrode connector 142 at both ends of the piezoelectric expansion member 140 along the second direction, the positive electrode connector 141 and the negative electrode connector 142 can be prevented from occupying space in the first direction, thereby making the structure of the cell stack 100 more compact.

[0101] Furthermore, by positioning the positive terminal 141 and the negative terminal 142 at both ends of the piezoelectric expansion member 140 along the second direction, it is possible to prevent the positive terminal 141 and the negative terminal 142 from being blocked by adjacent cells 110 or piezoelectric expansion members 140, so that the positive terminal 141 and the negative terminal 142 can be more easily connected to the second electrical connector 170.

[0102] The number of second electrical connectors 170 can also be set to two, and the two second electrical connectors 170 can be respectively disposed at both ends of the piezoelectric expansion member 140 along the second direction. One of the second electrical connectors 170 can be connected to the positive terminal connectors 141 of the multiple piezoelectric expansion members 140, and the other second electrical connector 170 can be connected to the negative terminal connectors 142 of the multiple piezoelectric expansion members 140.

[0103] In some embodiments, referring to FIG2, the restraint assembly 200 of this application may include a first restraint portion 220 and a second restraint portion 230. The first restraint portion 220 is connected to the second restraint portion 230, and the second restraint portion 230 is opposite to both ends of the cell stack 100 in a first direction. The first restraint portion 220 is disposed along the first direction such that the surface of the first restraint portion 220 faces the outer wall perpendicular to the first direction. The second restraint portion 230 may be pressed onto both ends of the cell stack 100 in the first direction, thereby suppressing the expansion deformation of the cell stack 100 in both directions of the first direction. Since the second restraint portion 230 is connected to the first restraint portion 220, the first restraint portion 220 can also suppress the expansion deformation of the cell stack 100 in both directions of the first direction. Furthermore, the first restraint portion 220 can also suppress the expansion deformation of the cell stack 100 in directions perpendicular to both the first and second directions.

[0104] In some embodiments, referring to FIG1, the surface of the cell stack 100 of this application covers the first orthographic projection, such that the entire first orthographic projection is located on the surface of the cell stack 100. This makes the entire restraint component 200 wrapped around the surface of the cell stack 100, thereby saving the material used for the restraint component 200 and reducing the manufacturing cost of the battery module 10 of this application.

[0105] In some embodiments, referring to FIG5, the restraint assembly 200 of this application may include multiple restraint wires 210, each of which is a long, thin, filamentous structure. All multiple restraint wires 210 are wound around the cell stack 100. Each of the multiple restraint wires 210 can generate a restraining force on the cell stack 100, and the restraining forces generated by the multiple restraint wires 210 on the cell stack 100 can be superimposed to form the restraining force generated by the restraint assembly 200 on the cell stack 100.

[0106] By setting the restraint assembly 200 to include multiple restraint wires 210, such that the diameter of each restraint wire 210 is relatively small, the process of winding each restraint wire 210 around the cell stack 100 can be relatively simpler, thereby reducing the manufacturing process cost of the battery module 10 of this application.

[0107] Multiple restraint wires 210 can be wound at intervals around the cell stack 100. Correspondingly, the number of restraint wires 210 is relatively smaller, and the material of the restraint wires 210 can be a material with higher tensile strength. This can reduce the amount of restraint wires 210 used, thereby reducing the cost of the battery module 10 of this application.

[0108] At least some of the multiple restraint wires 210 can be stacked, resulting in a relatively larger number of restraint wires 210. The restraint wires 210 can be made of materials with higher tensile strength, which can enhance the restraint force of the restraint assembly 200. Alternatively, the restraint wires 210 can be made of materials with relatively lower tensile strength to reduce the cost of the battery module 10 of this application.

[0109] Specifically, the tensile strength and quantity of the restraint wires 210 can be flexibly determined according to the expansion force of the battery cell 110, so as to ensure that the restraint force of the restraint assembly 200 on the battery cell stack 100 can fully suppress the expansion trend of the battery cell 110 while keeping costs lower.

[0110] Multiple restraint wires 210 can also be arranged adjacently, that is, multiple restraint wires 210 can be arranged sequentially along multiple directions, and adjacent restraint wires 210 can be in contact or not in contact.

[0111] In some embodiments, the restraint wire 210 of this application has a cross-section in the first direction. Specifically, when the restraint wire 210 is cylindrical, the cross-section in the first direction is the cross-section along the axial direction of the restraint wire 210, and the cross-section in the first direction is circular. Correspondingly, the area of ​​the cross-section of the restraint wire 210 in the first direction determines the thickness of the restraint wire 210. The larger the area of ​​the cross-section of the restraint wire 210 in the first direction, the thicker the restraint wire 210, and the greater the restraining force exerted by the restraint wire 210 on the cell stack 100. The smaller the area of ​​the cross-section of the restraint wire 210 in the first direction, the thinner the restraint wire 210, and the smaller the restraining force exerted by the restraint wire 210 on the cell stack 100. The sum of the cross-sectional areas of multiple restraint wires 210 in the first direction constitutes the cross-sectional area of ​​the restraint assembly 200 in the first direction.

[0112] The cross-section of the restraint assembly 200 in the first direction satisfies the following formula:

[0113] S1≥F / (2×Rm).

[0114] Wherein, S1 is the cross-sectional area of ​​the restraint component 200 in the first direction, and F is the preset restraint force acting on the cell stack 100. When the restraint force of the restraint component 200 acting on the cell stack 100 is greater than or equal to the preset restraint force, the expansion degree of the cell 110 is less than the preset degree, so that the cell 110 can be charged and discharged safely and reliably. If the restraint force of the restraint component 200 acting on the cell stack 100 is less than F, then the restraint component 200 cannot sufficiently suppress the expansion trend of the cell 110, and the expansion degree of the cell 110 is greater than the preset degree, then the safety risk of the cell 110 during the charging and discharging process is greater. Rm is the tensile strength of the restraint wire 210 in the first direction. Since the restraint assembly 200 is wound around the cell stack 100, the portions of the restraint assembly 200 located on opposite sides of the cell stack 100 can provide restraint force acting on the cell stack 100. Therefore, 2 in the formula means that the portions of the restraint assembly 200 located on opposite sides of the cell stack 100 can provide restraint force acting on the cell stack 100.

[0115] Specifically, Rm is determined by the material of the restraint wire 210, and the value of S1 obtained by the above formula is the minimum cross-sectional area required by the restraint assembly 200 in the first direction when the battery module 10 of this application is safely and reliably charged and discharged. Specifically, the larger the cross-sectional area of ​​the restraint assembly 200 in the first direction, the greater the restraining force it can provide. In addition, the minimum diameter of a single restraint wire 210 can be obtained according to the number of restraint wires 210 included in the restraint assembly 200.

[0116] Furthermore, it should be understood that F in the above formula can also be obtained by the preset pressure acting on the end of the cell 110 along the first direction, and the area of ​​the end of the cell 110 in the first direction. The preset pressure is the minimum pressure acting on the cell 110 in the first direction required for the battery module 10 to operate safely and reliably. Specifically, F = P * S², where P is the preset pressure acting on the end of the cell 110 in the first direction, and S² is the area of ​​the end of the cell 110 in the first direction.

[0117] For example, when Rm is 2000MPa and F is 10MPa, the area ratio of S1 to S2 is 1:400. Therefore, the ratio of the cross-sectional area of ​​the restraint assembly 200 in the first direction to the area of ​​the end of the cell 110 in the first direction must be at least 1:400 to ensure that the restraint force provided by the restraint assembly 200 can meet the interface requirements of the cell 110 during the charging and discharging process.

[0118] It should also be understood that the aforementioned F can be measured experimentally using other testing equipment. Specifically, pressure can be applied to both opposite sides of the cell stack 100 using a pressurizing device, and the cell stack 100 can be charged and discharged. The pressure applied to both opposite sides of the cell stack 100 by the pressurizing device can be adjusted. By applying different magnitudes of pressure to both opposite sides of the cell stack 100 and measuring the degree of expansion of the cell stack 100 under different pressure magnitudes, the minimum pressure required for the cell stack 100 to maintain a preset expansion range can be determined, thereby obtaining the minimum restraint force F required for the cell stack 100 to maintain structural stability.

[0119] In some embodiments, referring to FIG1, the cell stack 100 of this application may further include at least one end plate 120. Specifically, there are two end plates 120, both of which are stacked on the cell 110 along the first direction, and the two end plates 120 are located on opposite sides of the two outermost cells 110. The two end plates 120 can clamp the multiple cells 110, thus preventing the ends of the cells 110 from being exposed in the first direction, and serving the purpose of protecting and limiting the cells 110.

[0120] It should be understood that, because the restraint wire 210 of the restraint assembly 200 is relatively thin, if the restraint wire 210 is directly wound around the end of the battery cell 110 along the first direction, it will create a large pressure on the end of the battery cell 110, which could easily damage the battery cell 110. Therefore, the restraint assembly 200 is also wound around the end plate 120. The end plate 120 can separate the restraint assembly 200 from the end of the battery cell 110 along the first direction, preventing the restraint assembly 200 from being directly pressed onto the end of the battery cell 110 along the first direction, so as to avoid excessive pressure on the end of the battery cell 110 and damage to the battery cell 110.

[0121] When there is only one end plate 120, the end plate 120 can be stacked on any side of the cell stack 100 along the first direction.

[0122] In some embodiments, referring to Figures 6 and 7, the piezoelectric expansion member 140 may be disposed between the end plate 120 and the adjacent cell 110, so that the piezoelectric expansion member 140 can be connected to the end plate 120 and abut against the cell 110, so that the piezoelectric expansion member 140 is installed stably.

[0123] The piezoelectric expansion element 140 can also be disposed between adjacent cells 110, so that the restraining force generated by the thermal expansion of the piezoelectric expansion element 140 can also act on the cell 110. Specifically, a piezoelectric expansion element 140 can be disposed between each group of adjacent cells 110 so that the restraining force acting on each cell 110 can be finely adjusted.

[0124] In some embodiments, referring to Figures 1 and 2, the surface of the end plate 120 facing away from the cell 110 can be configured to have an arc surface, and the restraint assembly 200, when wound around the end plate 120, contacts the side of the end plate 120 facing away from the cell 110. By configuring the surface of the end plate 120 facing away from the cell 110 as an arc surface, the restraint force exerted by the restraint assembly 200 on the end plate 120 can be evenly diffused, making the restraint force distribution of the restraint assembly 200 on the end plate 120 more uniform, thereby making the restraint force exerted by the restraint assembly 200 on the cell stack 100 more uniformly distributed. In this way, the restraint assembly 200 can better provide the cell stack 100 with a restraint force that can suppress the expansion deformation of the cell stack 100.

[0125] In addition, the surface of the end plate 120 facing away from the cell 110 can be configured to have an arc surface, which can also avoid sharp structures on the side of the end plate 120 facing away from the cell 110, thereby fully converting the restraining force provided by the restraining wire 210 into stress along the axial direction of the restraining wire 210, thereby avoiding the restraining wire 210 from being subjected to large shear stress and reducing the risk of the restraining wire 210 breaking.

[0126] Specifically, the side surface of the end plate 120 facing away from the battery cell 110 can be configured to have a continuous arc surface, that is, the side surface of the end plate 120 facing away from the battery cell 110 is a circular arc segment, so that when the restraint wire 210 is wound on the end plate 120, it can fully contact the side surface of the end plate 120 facing away from the battery cell 110.

[0127] The surface of the end plate 120 facing away from the cell 110 can also be configured as a multi-segment arc surface, which can also avoid sharp structures on the side of the end plate 120 facing away from the cell 110.

[0128] In some embodiments, referring to Figures 1, 6, and 7, to allow the surface of the end plate 120 facing away from the battery cell 110 to be configured as an arc surface, the end plate 120 includes an abutment portion 121 and a winding portion 122. The abutment portion 121 abuts against the end of the battery cell 110 in a first direction. The winding portion 122 is connected to the abutment portion 121, and the winding portion 122 is located on the side of the abutment portion 121 facing away from the battery cell 110; correspondingly, the surface of the winding portion 122 facing away from the abutment portion 121 has an arc surface structure.

[0129] Specifically, the side of the abutment portion 121 facing the battery cell 110 is flat, allowing the abutment portion 121 to fully contact the end of the battery cell 110 in the first direction, thus making the restraining force exerted by the abutment portion 121 on the battery cell 110 more uniform. The restraint assembly 200 is wound around the surface of the winding portion 122 facing away from the abutment portion 121. The connection between the winding portion 122 and the abutment portion 121 can be set as an arc transition, which can avoid sharp structures at the connection between the winding portion 122 and the abutment portion 121. Correspondingly, the shear stress on the restraint wire 210 at the connection between the winding portion 122 and the abutment portion 121 can be reduced, further reducing the risk of the restraint wire 210 breaking.

[0130] In some embodiments, referring to Figures 1, 6, and 7, the two ends of the winding portion 122 in this application can be connected to the two ends of the abutment portion 121 in its extending direction, respectively, and a cavity 124 is formed between the winding portion 122 and the abutment portion 121. Specifically, the middle section of the winding portion 122 in its extending direction has a gap with the abutment portion 121 to form the cavity 124. This reduces the amount of material used in the preparation of the end plate 120, thereby reducing the weight of the end plate 120 and lowering its manufacturing cost.

[0131] The end plate 120 of this application also includes a support portion 123, which is located in the cavity 124 between the abutment portion 121 and the winding portion 122. The two ends of the support portion 123 are respectively connected to the abutment portion 121 and the winding portion 122. The support portion 123 can support the winding portion 122 and prevent the winding portion 122 from deforming towards the abutment portion 121 after being restrained by the restraining force of the restraining component 200, thereby enabling the end plate 120 as a whole to maintain better structural strength.

[0132] Specifically, one end of the support portion 123 can be connected to the middle portion of the abutment portion 121, and the other end of the support portion 123 can be connected to the middle portion of the winding portion 122, thereby making the supporting force of the support portion 123 on the winding portion 122 more balanced. The number of support portions 123 can also be multiple, with each support portion 123 located in the gap between the abutment portion 121 and the winding portion 122, and both ends of each support portion 123 connected to the abutment portion 121 and the winding portion 122 respectively. All the support portions 123 can support the winding portion 122, thereby further preventing the winding portion 122 from deforming towards the abutment portion 121 after being restrained by the restraining force of the restraining component 200, resulting in better overall structural strength of the end plate 120.

[0133] One end of each of the multiple support portions 123 can be connected to the middle part of the abutment portion 121, and the other end of each of the multiple support portions 123 can be arranged at intervals along the circumference of the winding portion 122. In this way, the multiple support portions 123 are arranged radially along the arc surface of the winding portion 122 on the side opposite to the abutment portion 121, so that the winding portion 122 is supported by the support portions 123 more evenly.

[0134] In some embodiments, referring to FIG1, the end plate 120 of this application forms a second orthographic projection on the cell 110 along a first direction. The second orthographic projection is covered by the cell 110, that is, the second orthographic projection can be located inside the end of the cell 110 in the first direction. In this way, the side of the end plate 120 facing the cell 110 is in contact with the cell 110. Correspondingly, the cell 110 can be supported in the opposite direction on the side of the end plate 120 facing the cell 110, making the structure of the end plate 120 more stable. In addition, the material used in the end plate 120 can be reduced, thereby reducing the manufacturing cost of the battery module 10 of this application.

[0135] In some embodiments, referring to FIG1, the end plate 120 forms a second orthographic projection on the cell 110 along the first direction, which can coincide with the cell 110. In this way, the second orthographic projection can just cover the end of the cell 110 along the first direction, so that the end plate 120 can fully cover the cell 110 to avoid the end of the cell 110 being exposed in the first direction. The end plate 120 can fully protect the cell 110.

[0136] Furthermore, the overlap between the end plate 120 and the end of the battery cell 110 in the first direction allows for a continuous transition at the connection between the end plate 120 and the adjacent battery cell 110, preventing sharp structures from appearing at the connection. This reduces the shear stress on the restraint wire 210 at the connection between the end plate 120 and the adjacent battery cell 110 when the restraint wire 210 passes through it, thereby lowering the risk of breakage.

[0137] In addition, in other embodiments, the area of ​​the second orthographic projection formed by the end plate 120 on the cell 110 along the first direction can be set to be smaller than the area of ​​the end of the cell 110 in the first direction. This can save the material used in the end plate 120, thereby reducing the cost of the battery module 10 of this application.

[0138] In some embodiments, referring to FIG1, after the multiple cells 110 of this application are connected in series, the cell stack 100 also needs to be provided with a positive terminal and a negative terminal, so that the multiple cells 110 of the cell stack 100 can be connected to an external electrical connection structure to enable the cells 110 to be charged and discharged. When the number of end plates 120 in this application is two, both end plates 120 can be electrically connected to the cells 110, and the two end plates 120 can serve as the positive terminal and the negative terminal of the cell stack 100, respectively. The external electrical connection structure can be electrically connected to the two end plates 120 to realize the electrical connection between the cell stack 100 and the external electrical connection structure.

[0139] By connecting the end plate 120 to the external electrical connection structure, it is not necessary to set up additional components for electrically connecting the cell 110 to the external electrical connection structure, thereby reducing the number of components in the battery module 10 of this application, simplifying the structure of the battery module 10, and reducing the cost of the battery module 10.

[0140] Specifically, in order to make the end plate 120 conductive, the end plate 120 is made of metal, which also gives the end plate 120 better structural strength. When the restraining force of the restraining component 200 is applied to the end plate 120, the end plate 120 can maintain structural stability and reliability.

[0141] In other embodiments, when there are two or more end plates 120, two of the end plates 120 can be electrically connected to the cell stack 100, while the other end plates 120 can be configured not to be electrically connected to the cell stack 100. Alternatively, all end plates 120 can be electrically connected to the cell stack 100, with two end plates 120 serving as the positive and negative terminals of the cell stack 100, respectively.

[0142] In some embodiments, referring to Figures 8 and 9, in order to make the multiple battery cells 110 electrically connectable, the battery cell stack 100 of this application may also be provided with a first electrical connector 130. The first electrical connector 130 is connected to the multiple battery cells 110 and two end plates 120. The multiple battery cells 110 can be electrically connected through the first electrical connector 130, and the end plates 120 can also be electrically connected to the battery cells 110 through the first electrical connector 130.

[0143] Specifically, the first electrical connector 130 can connect the tabs 111 of multiple battery cells 110 and connect the tabs 111 of the battery cells 110 to the end plate 120, thereby realizing the electrical connection between the multiple battery cells 110 and the end plate 120.

[0144] In some embodiments, referring to Figures 8 and 9, the first electrical connector 130 may include a plurality of electrical connection portions 131, which can connect to the tabs 111 of adjacent battery cells 110 and connect the end plate 120 to adjacent battery cells 110. Specifically, when the number of battery cells 110 is at least three, the three battery cells 110 can be electrically connected to adjacent battery cells 110 through two electrical connection portions 131. The two end plates 120 are respectively electrically connected to adjacent battery cells 110 through two electrical connection portions 131.

[0145] The electrical connection portion 131 can be connected to the tab 111 of the adjacent battery cell 110 by welding, so as to ensure a reliable connection between the electrical connection portion 131 and the tab 111 of the battery cell 110. The electrical connection portion 131 can also be connected to the end plate 120 and the tab 111 of the adjacent battery cell 110 by welding, so as to ensure a reliable connection between the electrical connection portion 131 and the end plate 120 and the tab 111 of the battery cell 110.

[0146] It should be noted that the electrical connection portion 131 and the electrode tab 111 are located on the same side of the battery cell 110, so that the electrical connection portion 131 and the electrode tab 111 can be arranged close to each other, making it convenient to connect the electrical connection portion 131 and the electrode tab 111. In addition, the electrical connection portion 131 and the first orthographic projection can be located on different sides of the surface of the battery cell 110, thereby avoiding mutual interference between the electrical connection portion 131 and the restraint assembly 200.

[0147] In some embodiments, referring to Figures 8 and 9, in order for the two end plates 120 to constitute the positive and negative connection terminals of the cell stack 100, one of the end plates 120 may be electrically connected to the first electrical connection portion 131 corresponding to the adjacent cell 110. This allows the end plate 120 to be electrically connected to the adjacent cell 110, thereby enabling the end plate 120 to serve as the positive connection terminal of the cell stack 100. The other end plate 120 may be electrically connected to the first electrical connection portion 131 corresponding to the adjacent cell 110. This allows the end plate 120 to be electrically connected to the adjacent cell 110, thereby enabling the end plate 120 to serve as the negative connection terminal of the cell stack 100.

[0148] Referring to Figure 10, the cell stack 100 further includes a positive electrode connection portion 150 and a negative electrode connection portion 160. The positive electrode connection portion 150 is electrically connected to one of the two end plates 120. The other end plate 120 is provided with the negative electrode connection portion 160, and the negative electrode connection portion 160 is electrically connected to the end plate 120. The positive electrode connection portion 150 and the negative electrode connection portion 160 are located on opposite sides of the two end plates 120. The positive electrode connection portion 150 and the negative electrode connection portion 160 can be connected to an external electrical connection structure, so that the cell stack 100 can be connected to an external electrical connection structure through the positive electrode connection portion 150 and the negative electrode connection portion 160.

[0149] The positive electrode connection portion 150 can be integrally formed with the corresponding end plate 120 to ensure a stable and reliable connection between the positive electrode connection portion 150 and the end plate 120. Specifically, the end plate 120 can be integrally formed with the positive electrode connection portion 150 during the fabrication process, thus eliminating the need for additional assembly of the positive electrode connection portion 150 and the end plate 120.

[0150] The negative electrode connection portion 160 can be integrally formed with the corresponding end plate 120 to ensure a stable and reliable connection between the negative electrode connection portion 160 and the end plate 120. Specifically, the end plate 120 and the negative electrode connection portion 160 can be integrally formed during the fabrication of the end plate 120, thus eliminating the need for additional assembly of the negative electrode connection portion 160 and the end plate 120.

[0151] In some embodiments, referring to Figures 11 and 12, the positive electrode connection portion 150 and the negative electrode connection portion 160 of the cell stack 100 of this application may also be configured to be electrically connected to the cell 110. The positive electrode connection portion 150 may serve as the positive electrode connection terminal of the cell stack 100, and the negative electrode connection portion 160 may serve as the negative electrode connection terminal of the cell stack 100.

[0152] In some embodiments, referring to Figures 11 and 12, the positive electrode connection 150 may be configured to connect to one of the plurality of electrical connection portions 131, thereby enabling the positive electrode connection 150 to be electrically connected to the battery cell 110 corresponding to that electrical connection portion 131. Similarly, the negative electrode connection 160 may be configured to connect to another of the plurality of electrical connection portions 131, thereby enabling the negative electrode connection 160 to be electrically connected to the battery cell 110 corresponding to that electrical connection portion 131. Correspondingly, the end plate 120 is non-conductive, and the material of the end plate 120 need not be metal, thereby reducing the manufacturing cost of the end plate 120.

[0153] Specifically, the positive electrode connection portion 150 and the negative electrode connection portion 160 can be located adjacent to both sides of the cell stack 100 in the first direction, and the positive electrode connection portion 150 and the negative electrode connection portion 160 are electrically connected to the two outermost cells 110 located in the first direction of the cell stack 100. The positive electrode connection portion 150 and the negative electrode connection portion 160 can also be distributed along the second direction on both sides of the cell stack 100.

[0154] In some embodiments, at least a portion of the end plate 120 of this application may also be a thermally expandable structure, the end plate 120 being used to expand under heat to compress the battery cell 110. When the temperature of the end plate 120 increases, the end plate 120 expands toward the battery cell 110, so that the end plate 120 can provide a restraining force to the battery cell 110, thereby more precisely adjusting the restraining force acting on the battery cell 110.

[0155] When the battery cell 110 is charged and discharged and has a tendency to expand, the temperature of the battery cell 110 will increase accordingly. The heat of the battery cell 110 can be transferred to the end plate 120, so that the part of the end plate 120 that is a thermal expansion structure can be heated and expand towards the battery cell 110. This allows the end plate 120 to provide a restraining force acting on the battery cell 110, so as to more fully suppress the expansion force of the battery cell 110.

[0156] Specifically, the abutment portion 121 in the end plate 120 can be a thermally expanding structural component, and the winding portion 122 of the end plate 120 can be a non-thermally expanding structural component, so that the winding portion 122 can better support the restraint assembly 200.

[0157] Based on the battery module 10 described above, this application also proposes a battery pack 20, as shown in Figure 13, including a tray 300 and the battery module 10 described above. The tray 300 is the basic component of the battery pack 20 of this application. The tray 300 can provide a mounting base for at least some other components of the battery pack 20 and serves to protect those components. The tray 300 can be made of metal, giving it better structural strength, thus improving its durability and reliability. Alternatively, some parts of the tray 300 can be made of polymer materials, allowing it to maintain a certain structural strength while remaining relatively lightweight.

[0158] The tray 300 has a battery cavity 310, which is a cavity-shaped structure within the tray 300. The battery module 10 can be disposed within the battery cavity 310 of the tray 300, thereby allowing the battery module 10 to be fixedly installed within the tray 300. The tray 300 also has an opening communicating with the battery cavity 310, through which the battery module 10 can be installed and removed from within the tray 300.

[0159] In some embodiments, referring to FIG13, the battery cavity 310 has two opposing abutting inner walls 311 along the first direction, and the opposite sides of the restraint assembly 200 abut against the two abutting inner walls 311 respectively. In this way, the tray 300 can also provide a restraining force acting on the cell stack 100 to more fully suppress the expansion tendency of the cell 110 along the first direction.

[0160] In some embodiments, referring to FIG14, the battery pack of this application may also include a detection element 400 and a control element 500, wherein the detection element 400 and the control element 500 are electrically connected, and the control element 500 is electrically connected to the piezoelectric expansion element 140.

[0161] Multiple piezoelectric expansion elements 140 can be connected via a second piezoelectric connector 170 and then electrically connected to the control element 500.

[0162] In some embodiments, the detection element 400 is configured to detect parameters of the battery cell 110, and the detection element 400 determines the degree of expansion of the battery cell 110 based on the parameters of the battery cell 110. The parameters of the battery cell 110 include at least one of the battery cell 110's state of charge, battery cell 110's state of health, battery cell 110's voltage, and battery cell 110's current. Specifically, the control element 500 can be a low-voltage module of the battery pack 20.

[0163] Specifically, the state of charge, health status, voltage, and current of the cell 110 can be comprehensively considered to form a more accurate estimate of the cell 110's expansion. The control unit 500 can control the expansion degree of the piezoelectric expansion member 140 to fully correspond to the expansion of the cell 110. This makes the battery pack of this application safer and more reliable during charging and discharging.

[0164] Referring to Figure 15, based on the battery module 10 or battery pack 20 described above, this application also proposes an electrical device 30, including the battery module 10 or battery pack 20 described above. This electrical device 30 can be a vehicle or an energy storage device.

[0165] In the description of this specification, the references to the terms "embodiment," "example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0166] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A battery module, characterized in that, include: A battery cell stack (100) includes a plurality of battery cells (110) and a piezoelectric expander (140), wherein the plurality of battery cells (110) and the piezoelectric expander (140) are stacked along a first direction, and the piezoelectric expander (140) is configured to expand upon being energized to compress the battery cells (110); A restraint assembly (200) is circumferentially disposed around the cell stack (100).

2. The battery module according to claim 1, characterized in that, The first direction is the thickness direction of the battery cell (110).

3. The battery module according to claim 2, characterized in that, The piezoelectric expansion member (140) forms a third orthographic projection on the cell (110) in the first direction, the third orthographic projection being located within the cell (110).

4. The battery module according to claim 1, characterized in that, The number of the piezoelectric expansion elements (140) is multiple, and the multiple piezoelectric expansion elements (140) are arranged along the first direction.

5. The battery module according to claim 4, characterized in that, The cell stack also includes a second electrical connector (170) connected to a plurality of the piezoelectric expansion elements (140).

6. The battery module according to claim 5, characterized in that, The second electrical connector (170) is also electrically connected to the battery cell (110) so that all of the plurality of piezoelectric expansion elements (140) are electrically connected to the battery cell (110).

7. The battery module according to claim 4, characterized in that, In the plurality of said cells (110), at least a portion of the adjacent cells (110) are provided with the piezoelectric expansion member (140).

8. The battery module according to claim 5, characterized in that, The piezoelectric expansion member (140) is provided with a positive terminal connector (141) and a negative terminal connector (142). There are two second electrical connectors (170). The positive terminal connector (141) is connected to one of the second electrical connectors (170), and the negative terminal connector (142) is connected to the other second electrical connector (170).

9. The battery module according to claim 8, characterized in that, The positive electrode connector (141) and the negative electrode connector (142) are disposed at both ends of the piezoelectric expansion member (140) along the second direction, and two second electrical connectors (170) are also located at both ends of the piezoelectric expansion member (140) along the second direction, the second direction intersecting the first direction.

10. The battery module according to any one of claims 1-9, characterized in that, The restraint assembly (200) forms a first orthographic projection on the surface of the cell stack (100), and the surface of the cell stack (100) covers the first orthographic projection.

11. The battery module according to claim 10, characterized in that, The restraint assembly (200) includes a plurality of restraint wires (210), which are spaced apart. Alternatively, multiple restraint wires (210) may be arranged adjacent to each other; Alternatively, at least some of the multiple restraint wires (210) may be stacked together.

12. The battery module according to claim 11, characterized in that, The restraint wire (210) is a carbon fiber wire and / or a metal wire.

13. The battery module according to claim 12, characterized in that, The cross-sectional area of ​​the restraint component (200) in the first direction satisfies: S1≥F / (2×Rm); Wherein, S1 is the cross-sectional area of ​​the restraint assembly (200) in the first direction, F is the preset restraint force acting on the battery cell stack (100), and Rm is the tensile strength of the restraint wire (210) in the first direction.

14. The battery module according to any one of claims 1-9, characterized in that, The cell stack (100) further includes at least one end plate (120), which is stacked on the cell (110) along the first direction, and the at least one end plate (120) is located outside the outermost cell (110) among the plurality of cells (110).

15. The battery module according to claim 14, characterized in that, The piezoelectric expansion member (140) is disposed between the end plate (120) and the adjacent battery cell (110).

16. The battery module according to claim 15, characterized in that, The end plate (120) has an arc surface on the side opposite to the battery cell (110).

17. The battery module according to claim 16, characterized in that, The end plate (120) includes an abutting part (121) and a winding part (122). The abutting part (121) abuts against the battery cell (110). The two ends of the winding part (122) in the extending direction are respectively connected to the abutting part (121). There is a cavity (124) between the winding part (122) and the abutting part (121).

18. The battery module according to claim 17, characterized in that, The end plate (120) further includes a support portion (123), which is located in the cavity (124) and is connected to the abutment portion (121) and the winding portion (122).

19. The battery module according to claim 14, characterized in that, The end plate (120) forms a second orthographic projection on the cell (110) along the first direction, and the second orthographic projection is covered by the cell (110).

20. The battery module according to claim 19, characterized in that, The second orthographic projection coincides with the battery cell (110).

21. The battery module according to claim 14, characterized in that, At least two end plates (120) are located at both ends of the cell stack (100) along the first direction, and a plurality of cells (110) are electrically connected. The plurality of cells (110) are electrically connected to at least two end plates (120), and the at least two end plates (120) respectively form the positive terminal and the negative terminal of the cell stack (100).

22. The battery module according to claim 20, characterized in that, The cell stack (100) further includes a first electrical connector (130) connected to the plurality of cells (110) and the two end plates (120).

23. The battery module according to claim 22, characterized in that, The first electrical connector (130) includes a plurality of electrical connection portions (131), which connect adjacent battery cells (110) and connect the end plate (120) to the adjacent battery cells (110).

24. The battery module according to claim 22, characterized in that, Positive electrode connection portion (150) and negative electrode connection portion (160) are respectively provided on opposite sides of the two end plates (120), and the positive electrode connection portion (150) and the negative electrode connection portion (160) are electrically connected to the corresponding end plate (120).

25. The battery module according to any one of claims 1-9, characterized in that, The battery module further includes a positive electrode connection part (150) and a negative electrode connection part (160), both of which are electrically connected to the battery cell (110). The positive electrode connection part (150) and the negative electrode connection part (160) respectively constitute the positive electrode connection end and the negative electrode connection end of the battery cell stack (100).

26. The battery module according to claim 25, characterized in that, The positive electrode connection (150) is electrically connected to one of the outermost of the plurality of battery cells (110), and the negative electrode connection (160) is electrically connected to another of the outermost of the plurality of battery cells (110).

27. A battery pack, characterized in that, The device includes a tray (300) and a battery module (10) as claimed in any one of claims 1-26, the tray (300) having a battery cavity (310) and the battery module (10) disposed within the battery cavity (310).

28. The battery pack according to claim 27, characterized in that, Along the first direction, the battery cavity (310) has two opposing abutting inner walls (311), and the opposite sides of the restraint assembly (200) abut against the two abutting inner walls (311) respectively.

29. The battery pack according to claim 28, characterized in that, The battery pack (20) further includes a detection element (400) and a control element (500), the detection element (400) and the control element (500) being electrically connected, and the control element (500) being electrically connected to the piezoelectric expansion element (140); The detection element (400) is configured to detect the expansion of the battery cell (110), and the control element (500) controls the degree of expansion of the piezoelectric expansion element (140) according to the expansion of the battery cell (110).

30. The battery pack according to claim 29, characterized in that, The detection element (400) is configured to detect the parameters of the battery cell (110), and the detection element (400) determines the degree of expansion of the battery cell (110) based on the parameters of the battery cell (110).

31. An electrical device comprising a battery module (10) as claimed in any one of claims 1-26, or comprising a battery pack (20) as claimed in any one of claims 27-30.

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