Electrochemical device and electronic device

Abstract

An electrochemical device, comprising a housing, an electrode assembly, an electrolyte, a bonding member, and a first expansion tape. The electrolyte is accommodated within the housing. The electrode assembly comprises a first electrode sheet, a second electrode sheet, and a separator. The electrode assembly is a wound structure wound around a central winding axis and is disposed within the housing. The first electrode sheet comprises a first section, the first section is a tail section of the first electrode sheet and is located at the outermost layer of the electrode assembly. Both an inner surface facing the central winding axis and an outer surface facing away from the central winding axis of the first section are foil-free areas. The first section comprises a terminal end. The bonding member bonds the terminal end and extends beyond the terminal end in a winding direction. The first expansion tape is bonded to the inner surface of the first section; in addition, the outer surface of the first section abuts against the housing by means of the first expansion tape to achieve electrical connection between the first electrode sheet and the housing, thereby facilitating the improvement of the energy density and stability of electrical connection of the electrochemical device. An electronic device applying the electrochemical device is also provided.

Description

Electrochemical devices and electronic devices Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to an electrochemical device and an electronic device having the electrochemical device. Background Art

[0002] Electrochemical devices (such as batteries) are widely used in electronic products such as mobile devices, power tools, and electric vehicles. Traditional hard-shell battery assembly typically involves placing a wound battery cell within a rigid casing. The tab of one electrode (e.g., the negative electrode) is then welded (e.g., laser welded) to the casing to achieve an electrical connection between the electrode and the casing.

[0003] However, the method of welding the tab to the shell reduces the energy density of the battery due to the space occupied. At the same time, since a welding needle needs to be inserted into the winding center of the battery cell to hold the tab against the shell during welding, the above-mentioned electrical connection method between the pole piece and the shell is either prone to unstable electrical connection due to the welding needle being too small, or requires a larger space for the large welding needle, resulting in a reduction in the energy density of the battery, thereby affecting the service life of the battery.

[0004] Summary of the Invention

[0005] Therefore, the present application proposes an electrochemical device that is beneficial for improving energy density and electrical connection stability.

[0006] In addition, the present application also provides an electronic device having the electrochemical device.

[0007] The first aspect of the present application provides an electrochemical device, comprising a shell, an electrode assembly, an electrolyte, an adhesive and a first expansion tape. The electrolyte is contained in the shell. The electrode assembly comprises a first electrode plate, a second electrode plate and an isolation membrane disposed between the first electrode plate and the second electrode plate. The electrode assembly is a winding structure wound around a winding center axis and disposed in the shell. The first electrode plate comprises a first section, which is the tail section of the first electrode plate and is located at the outermost layer of the electrode assembly. The inner surface of the first section facing the winding center axis and the outer surface away from the winding center axis are both empty foil areas. The first section comprises a tail end. The adhesive is bonded to the tail end and extends beyond the tail end in the winding direction to bond to the area of ​​the first electrode plate other than the tail end. The first expansion tape is bonded to the inner surface of the first section, and the outer surface of the first section is abutted against the shell through the first expansion tape to achieve electrical connection between the first electrode plate and the shell.

[0008] The present application uses adhesives to secure the electrode assembly, facilitating placement of the electrode assembly in the housing. By bonding a first expansion tape to the inner surface of the first section, the first expansion tape can abut the outer surface of the first section against the housing after expansion, thereby improving the stability of the electrical connection between the outer surface of the first section and the housing. Furthermore, the electrical connection between the housing and the first electrode piece is achieved by directly abutting the housing with the first section of the first electrode piece, eliminating the need for separate tabs for welding electrical connections to the housing. This not only improves the stability of the electrical connection, but also improves space utilization, thereby facilitating an increase in the overall energy density of the electrochemical device. After the electrochemical device undergoes subsequent charge and discharge cycles, the electrode assembly will further expand, pressing the outer surface of the first section against the housing, further stabilizing the electrical connection between the first electrode piece and the housing.

[0009] In some possible implementations, the adhesive is a conductive adhesive film, and the inner surface of the adhesive facing the winding center axis and the outer surface away from the winding center axis are both conductive and electrically connected, so that the adhesive can fix the electrode assembly to facilitate the placement of the electrode assembly in the shell, and can also contact the shell through the adhesive to further improve the stability of the electrical connection between the shell and the first electrode sheet.

[0010] In some possible implementations, the outermost portion of the electrode assembly is a hollow foil area of ​​the first electrode sheet. This increases the area of ​​the first electrode sheet that can directly contact the housing after the first expansion tape expands and after the electrode assembly further expands after subsequent charge and discharge cycles, thereby further enhancing the stability of the electrical connection between the housing and the first electrode sheet. Furthermore, when the adhesive member is also the aforementioned conductive adhesive film, the entire outer surface of the structure formed by the adhesive member and the electrode assembly can achieve electrical connection between the first electrode sheet and the housing. This means that no matter which area of ​​the structure formed by the adhesive member and the electrode assembly contacts the housing, the electrical connection between the first electrode sheet and the housing is maintained, thereby ensuring the stability of the electrical connection between the housing and the first electrode sheet.

[0011] In some possible implementations, the inner surface of the outermost circle of the first electrode sheet facing the winding center axis is a hollow foil area, and the first expansion tape is bonded to the inner surface of the outermost circle of the first electrode sheet and wrapped around the winding center axis, so that when the first expansion tape expands and during subsequent cyclic charge and discharge processes, the entire circumference of the electrode assembly around the winding center axis can expand outward along the radial direction of the electrode assembly, which is beneficial to balancing the diameter distribution of the electrode assembly in various directions of the surface perpendicular to the winding center axis, and is beneficial to the fixation between the electrode assembly and the shell, thereby further improving the stability of the electrical connection between the first electrode sheet and the shell.

[0012] In some possible implementations, the shell is cylindrical and the electrode assembly is cylindrical. The electrode assembly also includes a pole ear, and the second pole piece has a connection area, and the connection area is connected to the pole ear. The first expansion tape has a first notch, and in the radial direction of the electrode assembly, the first notch corresponds to the connection area. Compared with the flat electrode assembly and shell, the cylindrical electrode assembly matches the cylindrical shell, and when the first expansion tape expands, the expansion force of the entire circumference of the cylinder is more uniform, which is beneficial to improve the stability of the contact between the first pole piece and the shell; at the same time, compared with the expansion force required for the bending area of ​​the flat electrode assembly when it expands, the expansion force required for each area of ​​the cylindrical electrode assembly is smaller, which is beneficial to reduce the pulling force on the area where the first pole piece and the first expansion tape are bonded, and further helps to reduce the risk of the first pole piece tearing or even breaking in the bending area. In addition, since the connection between the connection area and the electrode ear will increase the thickness of the electrode assembly in this area, opening a first notch corresponding to the connection area on the first expansion tape can reduce the thickness of the area corresponding to the electrode assembly and the connection area, which is beneficial to balancing the thickness of each area of ​​the electrode assembly and is beneficial to the stability of the contact between the electrode assembly and the shell.

[0013] In some possible implementations, the first expansion tape has a second notch. In the radial direction of the electrode assembly, the second notch corresponds to the connection region, and the second notch and the first notch are located on opposite sides of the connection region. The first and second notches located radially on opposite sides of the connection region can help reduce the thickness of the electrode assembly corresponding to the connection region, thereby further balancing the thickness of various regions of the electrode assembly and further improving the stability of the contact between the electrode assembly and the housing.

[0014] In some possible implementations, the first pole piece also includes a second section, the second section is located in the secondary outer circle of the first pole piece, and the second section is stacked and adjacent to the first section. No second pole piece is provided between the first section and the second section, which is beneficial to reducing the thickness of the area corresponding to the electrode assembly and the first section, thereby balancing the thickness of each area of ​​the electrode assembly, improving the stability of the contact between the electrode assembly and the shell, and reducing the risk of short-circuiting of the positive and negative poles of the outer layer of the electrode assembly under the action of a larger expansion pressure.

[0015] In some possible implementations, the end of the separator is located between the first expansion tape and the second section. When the first expansion tape expands, its expansion force can compress the end of the separator, thereby restraining the end of the separator, thereby reducing the risk of shrinkage of the end section of the separator. If the first expansion tape is double-sided tape, the first expansion tape can further adhere to the end of the separator, further inhibiting shrinkage and further reducing the corresponding risk.

[0016] In some possible implementations, the first expansion tape is single-sided tape. In the winding direction, the tail end of the first expansion tape extends beyond the tail end of the separator. This not only saves separator film and reduces costs, but also allows the expansion force of the first expansion tape to compress the tail end of the separator film, thereby restraining the tail end and reducing the risk of separator film shrinkage. Using single-sided tape as the first expansion tape helps reduce excessive pulling on the separator film during expansion, thereby reducing the risk of separator film tearing.

[0017] In some possible implementations, the shell is cylindrical, the electrode assembly is cylindrical, and the first expansion tape overlaps with the adhesive in the radial direction of the electrode assembly. If the adhesive is too firmly bonded, the outermost ring of the first electrode piece may easily develop a small gap at the edge or even break due to the expansion force of the first expansion tape when it expands. However, the first expansion tape overlaps with the adhesive in the radial direction of the electrode assembly. At this time, when the first expansion tape expands, it can exert an outward force on the area of ​​the adhesive piece that overlaps with the first expansion tape, which is conducive to loosening the bond between the area of ​​the adhesive piece that does not overlap with the first expansion tape and the first electrode piece, thereby helping to reduce the binding force of the adhesive piece on the electrode assembly. While helping to reduce the risk of the outermost ring of the first electrode piece breaking, it also helps to facilitate close contact between the outermost ring of the first electrode piece and the shell, thereby helping to improve the stability of the electrical connection between the first electrode piece and the shell.

[0018] In some possible implementations, the adhesive is a single-sided adhesive, which is beneficial for reducing the obstruction of loosening caused by the adhesion between the adhesive and the shell when the wound electrode assembly has a certain tendency to loosen under the action of expansion, thereby facilitating the stability of the electrical connection between the first electrode and the shell.

[0019] In some possible implementations, in the winding direction, the tail end of the first pole piece extends beyond the tail end of the first expansion tape. This is beneficial for reducing the risk of breakage of the outermost circle of the first pole piece and the close contact between the outermost circle of the first pole piece and the shell, and is further beneficial for improving the adverse effects caused by inaccurate positioning of the first pole piece during continuous production.

[0020] In some possible implementations, the adhesive member includes a first end and a second end spaced apart in a winding direction, wherein the second end extends beyond the tail end of the first pole piece in the winding direction. In the winding direction, the first end is spaced apart from the tail end of the first pole piece by a distance L, wherein the distance between the tail end of the first expansion tape and the tail end of the first pole piece is less than or equal to L / 2. This helps to further improve the adverse effects caused by inaccurate positioning of the first pole piece during continuous production, further reduces the risk of fracture of the outermost circle of the first pole piece, and further ensures close contact between the outermost circle of the first pole piece and the housing.

[0021] In some possible implementations, in the winding direction, the tail end of the first expansion tape exceeds the tail end of the first pole piece or the tail end of the first expansion tape is flush with the tail end of the first pole piece. The first pole piece also includes a third section, which is the head section of the first pole piece. The surface of the third section facing the winding center axis is an empty foil area and is also bonded with a second expansion tape. First of all, the arrangement of the above-mentioned first expansion tape and the second expansion tape is conducive to reducing the adverse effects of inaccurate cutting positioning during continuous production (that is, first laying the expansion tape on the continuous empty foil area, and then cutting the empty foil area). Products with expansion tapes at both the head section and the tail section and the expansion tapes at least flush with the tail end of the first pole piece are easier to obtain during continuous production than products with expansion tapes only at the tail section. In addition, the fact that the tail end of the first expansion tape is at least flush with the tail end of the first pole piece is also conducive to reducing the impact of burrs on the edge of the first pole piece. In addition, the force exerted by the second expansion tape bonded to the head section of the first pole piece after expansion can further increase the interaction between the first pole piece, the isolation membrane and the second pole piece, so as to enhance the tightness of the contact interface between the first pole piece and the isolation membrane located in the inner layer of the electrode assembly and the contact interface between the second pole piece and the isolation membrane.

[0022] In some possible implementations, the electrode assembly has a center hole, and along the direction of the winding center axis, the projection of the winding center axis is located within the projection of the center hole. The electrochemical device also includes an insulating support member, which is at least partially arranged in the center hole. On the one hand, it is conducive to compressing the first electrode piece, the isolation membrane and the second electrode piece. On the other hand, it can also support the first expansion tape and the electrode assembly to expand outward along the radial direction of the electrode assembly when the first expansion tape expands and when the electrode assembly expands during subsequent cyclic charge and discharge, thereby helping to improve the stability of the electrical connection between the first electrode piece and the shell.

[0023] In some possible implementations, the material of the insulating support may include at least one of polypropylene or polyethylene, which can provide good supporting effects while also helping to reduce costs.

[0024] In some possible implementations, the first electrode sheet is a negative electrode sheet, which includes a negative electrode current collector, which is copper foil, and the shell is a steel shell. Since the expansion of the electrode assembly itself during the subsequent charge and discharge cycles of the electrochemical device is the main process, the active material in the negative electrode sheet expands the most, and when it expands, it will generate an extension force along the surface direction of the negative electrode current collector. Copper foil as a negative electrode current collector has high tensile strength and low resistivity, which helps to reduce the risk of current collector tearing and reduce the contact resistance between the negative electrode current collector and the shell. The steel shell helps to reduce the risk of electrochemical corrosion. In summary, the above design helps to extend the service life of the electrochemical device.

[0025] In some possible implementations, the first expandable tape has a thickness of 10 μm to 50 μm, and the negative electrode plate further includes a negative active layer comprising a silicon material, wherein the weight percentage of silicon in the negative active layer is 3% to 100%. This specific thickness of the first expandable tape helps ensure the expansion of the first expandable tape during formation (i.e., activation of the electrochemical device), thereby ensuring electrical connection between the first electrode plate and the housing, while also reducing the impact of excessive thickness of the first expandable tape on the energy density of the electrochemical device. Silicon material expands significantly during the cyclic charge and discharge process of the electrochemical device. Therefore, a negative active layer having a silicon material content within a specific range helps ensure the expansion of the negative active layer, i.e., the expansion of the electrode assembly itself, during cyclic charge and discharge, thereby improving the stability of the electrical connection between the first electrode plate and the housing during subsequent use of the electrochemical device.

[0026] In some possible implementations, the first expansion tape is made of at least one of polyisoprene, polybutadiene, or thermoplastic polyurethane elastomer, and further comprises at least one of acrylic glue, rubber, or silicone. Polyisoprene, polybutadiene, or thermoplastic polyurethane elastomers expand rapidly and at a high rate after being infiltrated with electrolyte, and this expansion does not subsequently reduce their volume, thereby ensuring the stability of the electrical connection between the first electrode piece and the housing. The acrylic glue, rubber, or silicone serves as an adhesive material to bond the at least one of polyisoprene, polybutadiene, or thermoplastic polyurethane elastomer to form a film layer, and also serves to bond the first electrode piece.

[0027] In some possible implementations, the conductive adhesive film includes an adhesive layer matrix and a conductor, the conductor is dispersed in the adhesive layer matrix, bonding with the electrode assembly is achieved through the adhesive layer matrix, and electrical connection between the first electrode in contact with the conductive adhesive film and the shell can be achieved through the conductor.

[0028] In some possible implementations, the adhesive layer matrix includes at least one of silicone rubber, polyurethane rubber, chloroprene rubber, hot melt adhesive, or tackifying resin, and the conductor includes at least one of gold, silver, copper, aluminum, nickel, or graphite. The use of such an adhesive layer matrix can maintain high adhesion in an electrolyte environment and is not susceptible to changes in electrolyte composition, thereby facilitating the preservation of the capacity and cycle life of the electrochemical device. Furthermore, the aforementioned conductors all have good electrical conductivity, thereby facilitating the stability of the electrical connection between the first electrode and the housing.

[0029] The present application also provides an electronic device comprising a main body and the electrochemical device. The electronic device is powered by the electrochemical device, and the electrochemical device has high reliability and service life, thereby extending the service life of the electronic device and reducing its use cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] FIG1A is a schematic structural diagram of an electrochemical device provided in one embodiment of the present application.

[0031] FIG1B is an exploded view of an electrochemical device provided in one embodiment of the present application.

[0032] FIG2 is a cross-sectional view of the electrochemical device shown in FIG1A along line II-II.

[0033] FIG3 is a cross-sectional view of an electrochemical device along line II-II provided in another embodiment of the present application.

[0034] FIG. 4 is a cross-sectional view of the electrochemical device shown in FIG. 1A taken along line II-II in one embodiment.

[0035] FIG. 5 is a cross-sectional view of the electrochemical device shown in FIG. 1A taken along line II-II in one embodiment.

[0036] FIG6 is a cross-sectional view of the electrochemical device shown in FIG1A taken along line II-II in one embodiment.

[0037] FIG. 7 is a cross-sectional view of the electrochemical device shown in FIG. 1A taken along line II-II in one embodiment.

[0038] FIG8 is a cross-sectional view of the electrochemical device shown in FIG1A taken along line II-II in one embodiment.

[0039] FIG. 9 is a cross-sectional view of the electrochemical device shown in FIG. 1A taken along line II-II in one embodiment.

[0040] FIG. 10 is a cross-sectional view of the electrochemical device shown in FIG. 1A taken along line II-II in one embodiment.

[0041] FIG11 is a schematic structural diagram of an electronic device according to an embodiment of the present application.

[0042] The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present application are described clearly and in detail below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present application. The terms used in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application.

[0044] Below, embodiments of the present application will be described in detail. However, the present application may be embodied in many different forms and should not be construed as limited to the exemplary embodiments illustrated herein. Rather, these exemplary embodiments are provided to make the present application thorough and detailed for those skilled in the art.

[0045] In addition, for the sake of brevity and clarity, the size or thickness of various components or layers may be exaggerated in the accompanying drawings. Throughout the text, the same numerical value refers to the same element. As used herein, the terms "and / or" and "and / or" include any and all combinations of one or more related enumerated items. In addition, it should be understood that when element A is referred to as "connecting" element B, element A can be directly connected to element B, or there may be an intermediate element C and element A and element B can be indirectly connected to each other.

[0046] Further, when describing embodiments of the present application, the use of “may” refers to “one or more embodiments of the present application.”

[0047] The technical terms used herein are for the purpose of describing specific embodiments and are not intended to limit this application. As used herein, the singular is intended to include the plural, unless the context clearly indicates otherwise. It should be further understood that the term "comprising", when used in this specification, refers to the presence of the described features, values, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, values, steps, operations, elements, components and / or combinations thereof.

[0048] Spatial related terms, such as "on" etc., can be used herein for convenient description, to describe the relationship between an element or feature and another element (multiple elements) or feature (multiple features) as illustrated in the figure. It should be understood that, in addition to the directions described in the figure, spatial related terms are intended to include different directions of equipment or devices in use or operation. For example, if the equipment in the figure is turned over, the elements described as "above" or "on" other elements or features will be oriented "below" or "below" other elements or features. Therefore, the exemplary term "on" can include the direction above and below. It should be understood that although the terms first, second, third, etc. can be used herein to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are used to distinguish an element, component, region, layer or part from another element, component, region, layer or part. Therefore, the first element, component, region, layer or part discussed below can be referred to as the second element, component, region, layer or part, without departing from the teachings of the exemplary embodiments.

[0049] In this application, the relationship between parameter values ​​that is greater than, less than, or not equal to the design relationship needs to exclude the reasonable error of the measuring equipment.

[0050] 1A to 2 , an embodiment of the present application provides an electrochemical device 100 comprising a housing 10, an electrode assembly 20, an electrolyte (not shown), an adhesive member 40, and a first expansion tape 50. The electrode assembly 20, the electrolyte, the adhesive member 40, and the first expansion tape 50 are contained within the housing 10.

[0051] 1A and 1B , in some embodiments, the housing 10 is a hard housing, and the housing 10 includes a conductive material, such as but not limited to aluminum, steel, etc. In some embodiments, specifically, the housing 10 may be a steel shell or an aluminum shell.

[0052] The housing 10 may include a first wall 11, a second wall 13, and a connecting wall 15 connecting the periphery of the first wall 11 and the periphery of the second wall 13. The first wall 11, the second wall 13, and the connecting wall 15 cooperate to form a storage cavity 10a. The connecting wall 15 may be made of a conductive material. The first wall 11 and the second wall 13 may be made of a conductive material or a non-conductive material. In some embodiments, the first wall 11 and the connecting wall are integrally formed. In some embodiments, a pole 17 may be provided on the second wall 13, and when the second wall 13 is conductive, the pole 17 and the second wall 13 may be electrically insulated.

[0053] Referring to Figure 2 , the electrode assembly 20 includes a first electrode sheet 21, a second electrode sheet 23, and a separator 25 disposed between the first electrode sheet 21 and the second electrode sheet 23. The first electrode sheet 21, the separator 25, and the second electrode sheet 23 are stacked sequentially and wound along a winding direction D around a winding axis O, so that the electrode assembly 20 forms a wound structure wound around the winding axis O. The electrode assembly 20 is disposed within the storage cavity 10a. The separator 25 prevents direct contact between the first electrode sheet 21 and the second electrode sheet 23, thereby preventing a short circuit in the electrode assembly 20. As shown in Figure 2 , the winding axis O is perpendicular to the paper, and the winding direction D is the direction of counterclockwise rotation about the winding axis O as shown in Figure 2 . In other embodiments, the winding direction D may also be a clockwise direction, as shown in Figure 1B . In this application, the electrode assembly 20 has a radial direction, where the radial direction refers to the direction of a straight line passing through the winding axis O within any cross-section of the electrode assembly perpendicular to the winding axis O.

[0054] The electrode assembly 20 can be roughly cylindrical (as shown in Figures 2 and 1B), flat (as shown in Figure 3), or other regular or irregular shapes. Correspondingly, the shell 10 roughly matches the shape of the electrode assembly 20. For example, as shown in Figure 2, when the electrode assembly 20 is roughly cylindrical, the shell 10 is also roughly cylindrical. For another example, as shown in Figure 3, when the electrode assembly 20 is roughly flat, the shell 10 is also roughly flat. In the present application, as shown in Figure 3, the flat electrode assembly is an electrode assembly structure that is common in the art and includes a straight portion and a bent portion connected to opposite ends of the straight portion. Below, the subsequent description will be based on the example of the cylindrical electrode assembly 20 and the cylindrical shell 10.

[0055] As shown in Figure 2, the first electrode sheet 21 includes a first section 211, which serves as the tail section of the first electrode sheet 21 and is located at the outermost layer of the electrode assembly 20, wherein the inner surface 211a of the first section 211 facing the winding center axis O and the outer surface 211b facing away from the winding center axis O are both hollow foil areas. In the present application, the hollow foil area is the area on the surface of the current collector that is not coated with the active material layer, that is, the first electrode sheet 21 includes the first current collector 21a and the first active material layer 21b, wherein the tail section of the first current collector 21a is the first section 211. The outermost layer of the electrode assembly 20, that is, the structure located at the outermost side of the electrode assembly 20 along the winding direction D, can be composed of the same structure, such as a pole sheet, or can be composed of a pole sheet and a separator. The first section 211 includes a tail end 211c, which is the tail end of the first pole sheet 21 in the winding direction D.

[0056] The electrode assembly 20 is located in the receiving cavity 10 a , wherein the outermost layer of the electrode assembly 20 faces the connecting wall 15 , that is, the outer surface 211 b of the first section 211 faces the connecting wall 15 .

[0057] The adhesive member 40 adheres to the tail end 211c and extends beyond the tail end 211c in the winding direction D to adhere to the area of ​​the first electrode sheet 21 excluding the tail end 211c, thereby maintaining the electrode assembly 20 in a wound state. The adhesive member 40 includes a first end 41 and a second end 43 spaced apart in the winding direction D. The second end 43 extends beyond the tail end 211c of the first electrode sheet 21 in the winding direction D. In some embodiments, the adhesive member 40 may span the tail end 211c in the winding direction D, with the first end 41 located on the outer surface 211b of the first segment 211.

[0058] The first expandable adhesive tape 50 is bonded to the inner surface 211a of the first section 211. After expansion, the first expandable adhesive tape 50 causes the outer surface 211b of the first section 211 to abut against the connecting wall 15 of the housing 10, thereby achieving electrical connection between the first electrode piece 21 and the housing 10. Specifically, to facilitate placement of the electrode assembly 20 within the receiving cavity 10a, the volume of the electrode assembly 20 is typically smaller than the volume of the receiving cavity 10a, i.e., there is typically a gap between the electrode assembly 20 and the connecting wall 15 of the housing 10. However, after being soaked by the electrolyte, the first expandable adhesive tape 50 expands, causing the region of the electrode assembly 20 where the first expandable adhesive tape 50 is located to expand outward in the radial direction, thereby abutting the first section 211 against the connecting wall 15 of the housing 10, thereby achieving electrical connection between the first electrode piece 21 and the housing 10. In addition, by directly connecting the housing 10 and the first electrode piece 21 through the first section 211 and the connecting wall 15 of the housing 10, there is no need to separately weld the electrode tab to the housing 10 (for example, the second wall 13 as the bottom wall) for electrical connection. This not only helps to improve the stability of the electrical connection, but also helps to improve space utilization and thus improve the overall energy density of the electrochemical device. Furthermore, after the electrochemical device undergoes cyclic charge and discharge, the electrode assembly 20 will further expand, thereby pressing the outer surface 211b of the first section 211 against the connecting wall 15 of the housing 10, thereby making the electrical connection between the first electrode piece 21 and the housing 10 more stable. It should be noted that in order to more clearly present the positional relationship of the various components in the drawings, the outer surface 211b is not placed in close contact with the connecting wall of the housing 10.

[0059] Since the first expandable tape 50 generates an extension force along the surface direction of the component to which it is bonded when it expands, the first expandable tape 50 is directly bonded to the inner surface 211a of the first segment 211 instead of the first active material layer 21b. This reduces the risk of the first active material layer 21b being peeled off due to the extension force. In addition, compared to the first active material layer 21b, the first segment 211, as part of the first current collector 21a, has a higher tear resistance when subjected to the extension force, thereby further reducing the adverse effects of the first expandable tape 50 on the performance of the electrochemical device.

[0060] In addition, compared with the flat electrode assembly and shell, the cylindrical electrode assembly 20 matches the cylindrical shell 10, and the expansion force of the entire circumference of the cylinder is more uniform when the first expansion tape 50 expands, which is beneficial to improving the stability of the contact between the first electrode piece 21 and the connecting wall 15 of the shell 10; at the same time, compared with the expansion force required for the bending area of ​​the flat electrode assembly when it expands, the expansion force required for each area of ​​the cylindrical electrode assembly 20 is smaller, which is beneficial to reducing the pulling force on the area where the first electrode piece 21 and the first expansion tape 50 are bonded, and thus helps to reduce the risk of tearing or even breaking the bending area of ​​the first electrode piece 21.

[0061] In some embodiments, the first electrode sheet 21 may further be a negative electrode sheet, in which case the first active material layer 21b is a negative active layer, and the first current collector 21a is a negative current collector, which may be copper foil. Since copper foil has high tensile strength and low resistivity as a current collector, it helps reduce the risk of current collector tearing when subjected to the aforementioned tensile force and reduces the contact resistance between the current collector and the housing. Accordingly, the housing 10 may be a steel shell, which helps reduce the risk of electrochemical corrosion. The above design overall helps extend the service life of the electrochemical device 100.

[0062] The first active material layer 21b may comprise a silicon material. Since silicon material has a high expansion rate during the cyclic charge and discharge process of the electrochemical device, the use of a first active material layer 21b containing a silicon material is beneficial for ensuring the expansion effect of the first active material layer 21b, that is, the expansion effect of the electrode assembly 20 itself, during the cyclic charge and discharge process, thereby facilitating the improvement of the stability of the electrical connection between the first electrode plate 21 and the connecting wall 15 of the housing 10 during subsequent use of the electrochemical device 100. In some embodiments, the weight percentage of silicon in the first active material layer 21b may be 3% to 100%. By ensuring the silicon content, the expansion effect of the electrode assembly 20 itself is ensured, thereby further improving the stability of the electrical connection between the first electrode plate 21 and the connecting wall 15 of the housing 10 during subsequent use of the electrochemical device 100.

[0063] In other embodiments, the first electrode sheet 21 may also be a positive electrode sheet, the first current collector 21 a may include aluminum foil, and the housing 10 may be an aluminum shell.

[0064] The thickness of the first expansion tape 50 can be 10 μm to 50 μm, which is beneficial for ensuring the expansion effect of the first expansion tape 50 during formation (i.e., activation of the electrochemical device) to facilitate the electrical connection between the first electrode 21 and the housing 10, while reducing the impact of the excessive thickness of the first expansion tape 50 on the energy density of the electrochemical device 100.

[0065] The material of the first expansion tape 50 may include, but is not limited to, at least one of polyisoprene, polybutadiene, or thermoplastic polyurethane elastomer, and may also include, but is not limited to, at least one of acrylic glue, rubber, or silicone. Polyisoprene, polybutadiene, or thermoplastic polyurethane elastomers can rapidly expand and have a high expansion rate after being soaked in electrolyte, and this expansion is not easily reduced in volume, thereby ensuring the stability of the electrical connection between the first electrode piece 21 and the connecting wall 15 of the housing 10. Acrylic glue, rubber, or silicone acts as an adhesive material to bond at least one of polyisoprene, polybutadiene, or thermoplastic polyurethane elastomer to form a film layer, and also serves to bond the first electrode piece 21. The first expansion tape 50 may be single-sided or double-sided adhesive.

[0066] In some embodiments, the adhesive member 40 may be a single-sided tape. In this case, it can reduce the situation where the adhesive member 40 simultaneously adheres to the electrode assembly 20 and the connecting wall 15 of the housing 10. When the electrode assembly 20 expands during subsequent charge and discharge cycles of the electrochemical device, the expansion can cause the adhesive member 40 to loosen. Reducing the adhesion between the adhesive member 40 and the connecting wall 15 of the housing 10 helps reduce the adhesive member 40's resistance to loosening the electrode assembly 20, thereby facilitating contact between the outermost layer of the electrode assembly 20 and the connecting wall 15 of the housing 10, thereby facilitating the stable electrical connection between the outer surface 211b of the first segment 211 and the housing 10. In other embodiments, the adhesive member 40 may also be a double-sided tape. Furthermore, in order to improve the stability of the electrical connection between the electrode assembly 20 and the shell 10, the adhesive 40 can also be a conductive adhesive film, wherein the inner surface 40a of the adhesive 40 facing the winding center axis O and the outer surface 40b away from the winding center axis O are both conductive, and there is electrical conduction between the inner surface 40a and the outer surface 40b, so that the adhesive 40 can fix the electrode assembly 20 to facilitate the placement of the electrode assembly 20 in the shell 10, and can also contact the connecting wall 15 of the shell 10 through the conductive adhesive 40 to further improve the stability of the electrical connection between the shell 10 and the first electrode plate 21.

[0067] In some embodiments, the conductive adhesive film may specifically include an adhesive layer matrix and a conductor. The adhesive layer matrix may include an adhesive material to achieve adhesion of the conductive adhesive film, while the conductor is dispersed in the adhesive layer matrix and contacts each other to achieve electrical conductivity. The adhesive layer matrix may include, but is not limited to, at least one of silicone rubber, polyurethane rubber, chloroprene rubber, hot melt adhesive, or tackifying resin. The use of such an adhesive layer matrix can maintain high adhesion in an electrolyte environment and is not susceptible to changes in electrolyte composition, thereby ensuring that the capacity and cycle life of the electrochemical device are not affected. The conductor may include, but is not limited to, at least one of gold, silver, copper, aluminum, nickel, or graphite. All of these conductors have good electrical conductivity, which helps ensure the stability of the electrical connection between the first electrode 21 and the housing 10.

[0068] Silicone rubber is primarily composed of siloxane chains containing methyl groups and a small amount of vinyl groups. Phenyl, trifluoropropyl, and cyano groups may also be introduced. Silicone rubber is divided into heat-vulcanized (high-temperature vulcanized silicone HTV) and room-temperature vulcanized (RTV) types. RTV types are further divided into polycondensation and addition reaction types. Heat-vulcanized silicone rubber is used in greater quantities and is further divided into methyl silicone rubber (MQ), methyl vinyl silicone rubber (VMQ, the most widely used and most widely available product), and methyl vinyl phenyl silicone rubber PVMQ (low-temperature and radiation-resistant). Other types include nitrile silicone rubber and fluorosilicone rubber. Polyurethane rubber (PU) is a series of elastomeric materials with a high concentration of carbamate groups in the polymer backbone. It is actually polyurethane rubber, also known as PU, urethane rubber, or polyurethane elastomer. In addition to carbamate groups, the polymer chain also contains ester, ether, urea, aromatic, and aliphatic chains. It is typically formed by the reaction of oligomeric polyols, polyisocyanates, and chain extenders. Polyurethane rubbers vary in structure and type depending on the raw materials used, their proportions, reaction methods, and conditions. Neoprene, also known as chloroprene rubber, is a synthetic rubber produced by α-polymerization of chloroprene (2-chloro-1,3-butadiene). Specific types include CR122, CR232, CR24412442, and CR321322. Hot melt adhesive is a plastic adhesive whose physical state changes with temperature within a certain temperature range, while its chemical properties remain unchanged. It is non-toxic, odorless, and environmentally friendly. The product itself is a solid, making it easy to package, transport, and store. It is solvent-free, pollution-free, and non-toxic. It also features a simple production process, high added value, and high bonding strength and speed. Tackifying resins are small molecule compounds that increase the adhesiveness of rubber materials, particularly surface adhesiveness. These small molecules typically have molecular weights ranging from several hundred to ten thousand and possess high glass transition temperatures. Based on their source and synthesis routes, they can be broadly categorized into two main groups: natural products and their derivatives, and synthetic resins. Tackifying resins are primarily used for polymer modification and are widely used in adhesives, coatings, inks, rubber compounds, asphalt modifiers, and polyolefin modifiers.

[0069] The conductor may be in the form of, but not limited to, at least one of conductive particles, conductive fibers, or conductive sheets.

[0070] As shown in FIG4 , in some embodiments, the outermost portion of the electrode assembly 20 is a hollow foil area of ​​the first electrode sheet 21. This increases the area of ​​the first electrode sheet 21 that can directly contact the connecting wall 15 of the housing 10 after the first expansion tape 50 expands and after subsequent charge and discharge cycles, regardless of the shape of the expanded electrode assembly 20. This helps further enhance the stability of the electrical connection between the housing 10 and the first electrode sheet 21. When the adhesive member 40 is the aforementioned conductive adhesive film, the entire outer surface of the structure formed by the adhesive member 40 and the electrode assembly 20 is made of a conductive material. This allows for electrical connection between the first electrode sheet 21 and the connecting wall 15 of the housing 10. Regardless of which area of ​​the structure formed by the adhesive member 40 and the electrode assembly 20 contacts the connecting wall 15 of the housing 10, the electrical connection between the first electrode sheet 21 and the housing 10 is maintained, thereby ensuring the stability of the electrical connection between the housing 10 and the first electrode sheet 21.

[0071] Please refer to Figure 4. The inner surface of the outermost circle of the first electrode sheet 21 facing the winding center axis O may be a hollow foil area. As shown in Figure 4, the first section 211 may be arranged around the winding center axis O for at least one circle. In the present application, the outermost circle refers to the area of ​​the membrane, such as the first electrode sheet 21, which is wound around the winding center axis O from its tail end 211c in the direction opposite to the winding direction D. The outermost circle of the first electrode sheet 21 includes two ends in the winding direction D, and the two ends (one end is the tail end 211c, and the other end is the starting end of the outermost circle) overlap in the radial direction of the electrode assembly 20. It can be understood that the secondary outer circle refers to the area where the starting end of the outermost circle is wound around the winding center axis O in the direction opposite to the winding direction D. In this way, the two ends of each circle of the membrane in the winding direction D overlap in the radial direction of the electrode assembly 20.

[0072] The first expansion tape 50 is bonded to the inner surface of the outermost circle of the first electrode piece 21 and can be wound around the winding center axis O for one circle, so that when the first expansion tape 50 expands and during subsequent cyclic charge and discharge processes, the electrode assembly 20 can expand outward in the radial direction of the electrode assembly 20 around the winding center axis O. This is beneficial to balancing the diameter distribution of the electrode assembly 20 in various directions of the surface perpendicular to the winding center axis O, and is beneficial to pressing the entire outer side of the electrode assembly 20 with the adhesive 40 against the connecting wall 15 of the shell 10, thereby facilitating the fixation between the electrode assembly 20 and the shell 10, and further improving the stability of the electrical connection between the first electrode piece 21 and the shell 10.

[0073] Referring to FIG. 1B , the electrode assembly 20 further includes a tab 26. The second electrode sheet 23 has a connection region 23a. One end of the tab 26 is connected to the electrode post 17, and the other end is connected to the connection region 23a. The connection between the tab 26 and the connection region 23a is typically achieved by welding, or alternatively, by bonding with a conductive adhesive. The connection between the tab 26 and the connection region 23a is typically covered with insulating tape (not shown). Therefore, it can be seen that the connection between the tab 26 and the connection region 23a increases the thickness of the electrode assembly 20 in that region. In some embodiments, referring to FIG. 5 , the first expansion tape 50 may have a first notch 51. In the radial direction of the electrode assembly 20, the first notch 51 overlaps and corresponds to the connection region 23a. This reduces the thickness of the electrode assembly 20 in the region corresponding to the connection region 23a, facilitating balancing the thickness of various regions of the electrode assembly 20 and enhancing the stability of the contact between the electrode assembly 20 and the connecting wall 15 of the housing 10.

[0074] In some embodiments, referring to FIG6 , the first expansion tape 50 may further include a second notch 53. In the radial direction of the electrode assembly 20, the second notch 53 is stacked and corresponds to the connection region 23a, and the second notch 53 and the first notch 51 are located on opposite sides of the connection region 23a, respectively. This can help reduce the thickness of the region of the electrode assembly 20 corresponding to the connection region 23a, thereby further balancing the thickness of various regions of the electrode assembly 20 and further improving the stability of the contact between the electrode assembly 20 and the connection wall 15 of the housing 10.

[0075] Referring to FIG. 2 , the first electrode piece 21 further includes a second segment 212 located at a secondary outer ring of the first electrode piece 21 . In the radial direction of the electrode assembly 20 , the first segment 211 and the second segment 212 are stacked and adjacent to each other. In some embodiments, as shown in FIG. 2 , the second electrode piece 23 may not extend between the first segment 211 and the second segment 212 , thereby facilitating a reduction in the thickness of the electrode assembly 20 in the region corresponding to the first segment 211 , thereby facilitating a balanced thickness distribution across various regions of the electrode assembly 20 and enhancing the stability of the contact between the electrode assembly 20 and the connecting wall 15 of the housing 10 .

[0076] In some embodiments, the tail end 25a of the isolation film 25 can be located between the first expansion tape 50 and the second section 212. When the first expansion tape 50 expands, its expansion force can compress the tail end 25a of the isolation film 25, thereby restraining the tail end 25a of the isolation film 25 and reducing the risk of shrinkage of the tail section of the isolation film 25. When the first expansion tape 50 is double-sided tape, the first expansion tape 50 can further adhere to the tail end 25a of the isolation film 25, further hindering the shrinkage of the isolation film 25 and further reducing the corresponding risk. When the first expansion tape 50 is single-sided tape, it can help reduce excessive pulling on the isolation film 25 when the first expansion tape 50 expands, thereby reducing the risk of tearing of the isolation film 25.

[0077] In some embodiments, in the winding direction D, the tail end 50a of the first expansion tape 50 may extend beyond the tail end 25a of the isolation film 25. This can save the isolation film 25 to reduce costs. On the other hand, the expansion force of the first expansion tape 50 during expansion can press against the tail end 25a of the isolation film 25 to restrain the tail end 25a of the isolation film 25, thereby reducing the risk of shrinkage of the isolation film 25.

[0078] As shown in Figure 2, the first expandable tape 50 and the adhesive member 40 can overlap in the radial direction of the electrode assembly 20. If the adhesive member 40 is too firmly bonded, the outermost ring of the first electrode plate 21 may easily develop small gaps or even break due to the expansion force of the first expandable tape 50. However, if the first expandable tape 50 overlaps with the adhesive member 40 in the radial direction of the electrode assembly 20, the expansion of the first expandable tape 50 can exert an outward force on the overlapping area of ​​the adhesive member 40, which helps loosen the bond between the non-overlapping area of ​​the adhesive member 40 and the first electrode plate 21. This helps reduce the binding force of the adhesive member 40 on the electrode assembly 20. This not only reduces the risk of breakage of the outermost ring of the first electrode plate 21, but also promotes close contact between the outermost ring of the first electrode plate 21 and the connecting wall 15 of the housing 10, thereby improving the stability of the electrical connection between the first electrode plate 21 and the housing 10.

[0079] As shown in FIG2 , in the winding direction D, the tail end 211 c of the first electrode piece 21 can extend beyond the tail end 50 a of the first expansion tape 50 , which facilitates cutting of the first electrode piece 21 during continuous production and helps reduce the adverse effects caused by inaccurate positioning of the first electrode piece 21 during continuous production.

[0080] Please refer to Figure 2, which defines the distance between the first end 41 of the adhesive member 40 and the tail end 211c of the first pole piece 21 in the winding direction D as L. In some embodiments, under the premise that the first expansion tape 50 overlaps with the adhesive member 40 and the tail end 211c of the first pole piece 21 exceeds the tail end 50a of the first expansion tape 50, the distance between the tail end 50a of the first expansion tape 50 and the tail end 211c of the first pole piece 21 can be less than or equal to L / 2, thereby helping to reduce the adverse effects caused by inaccurate positioning of the first pole piece 21 during continuous production, and further helping to reduce the risk of breakage of the outermost circle of the first pole piece 21 and helping to further ensure close contact between the outermost circle of the first pole piece 21 and the connecting wall 15 of the shell 10.

[0081] In some embodiments, as shown in FIG. 7 , in the winding direction D, the tail end 50a of the first expansion tape 50 may also extend beyond the tail end 211c of the first pole piece 21 or be flush with the tail end 211c of the first pole piece 21 , which is beneficial for reducing the impact of burrs on the edge of the first pole piece 21 .

[0082] As shown in FIG8 , the first electrode sheet 21 further includes a third section 216 serving as a leading section. In some embodiments, the surface of the third section 216 facing the winding axis O may be a hollow foil area and may be adhered with a second expansion tape 60. Referring to FIG1B and FIG8 , since a winding needle is used during winding of the electrode assembly 20 to enhance the winding effect, the electrode assembly 20 typically has a central hole 20a. Along the direction of the winding axis O, the projection of the winding axis O lies within the projection of the central hole 20a. Due to the presence of the central hole 20a, the interfaces of the electrode assembly 20 near the winding axis O are relatively loose and less tight. The presence of the second expansion tape 60, after expansion, further strengthens the interaction between the first electrode sheet 21, the separator 25, and the second electrode sheet 23, thereby enhancing the tightness of the contact interfaces between the first electrode sheet 21 and the separator 25, as well as the contact interfaces between the second electrode sheet 23 and the separator 25, located within the inner layer of the electrode assembly 20.

[0083] In some embodiments, as shown in Figure 8, further, when the tail end 50a of the first expansion tape 50 exceeds the tail end 211c of the first electrode 21 or is flush with the tail end 211c of the first electrode 21, and the second expansion tape 60 is adhered to the surface of the third section 216 facing the winding center axis O, the above-mentioned arrangement of the first expansion tape 50 and the second expansion tape 60 is conducive to reducing the adverse effects of inaccurate cutting positioning during continuous production (that is, first laying the expansion tape on the continuous empty foil area, and then cutting the empty foil area). Products with expansion tapes on both the head section and the tail section and the expansion tapes at least flush with the tail end 211c of the first electrode 21 are easier to obtain during continuous production than products with expansion tapes only on the tail section.

[0084] In other embodiments, as shown in FIG9 , in the winding direction D, the tail end 25 a of the isolation film 25 may extend beyond the tail end 50 a of the first expansion tape 50 or be flush with the tail end 50 a of the first expansion tape 50 , thereby facilitating greater restraint of the isolation film 25 by the expansion force of the first expansion tape 50 during expansion, thereby further reducing the risk of shrinkage of the isolation film 25 .

[0085] Please refer to Figure 1B and Figure 10 in combination. The electrochemical device may further include an insulating support member 70. The insulating support member 70 is inserted into the central hole 20a of the electrode assembly 20 so that the insulating support member 70 is at least partially disposed in the central hole 20a of the electrode assembly 20. On the one hand, this is conducive to compressing the first electrode piece 21, the isolation membrane 25 and the second electrode piece 23. On the other hand, it can also support the first expansion tape 50 and the electrode assembly 20 to expand outward along the radial direction of the electrode assembly 20 when the first expansion tape 50 expands and when the electrode assembly 20 expands during subsequent cyclic charge and discharge processes, thereby facilitating the improvement of the stability of the electrical connection between the first electrode piece 21 and the connecting wall 15 of the shell 10.

[0086] The material of the insulating support member 70 may include but is not limited to at least one of polypropylene or polyethylene, which can provide good supporting effects while also helping to reduce costs.

[0087] The electrochemical device 100 of any of the above embodiments may be applied to an electronic device. As shown in FIG11 , the electronic device 200 further includes a body 201 , and the electrochemical device 100 supplies power to the body 201 .

[0088] The electronic device 200 may be, but is not limited to, an electric toy, an electric vehicle, a mobile phone, a wearable device, a tablet, a computer, a drone, an energy storage device, etc.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. An electrochemical device, wherein: include: case; Adhesive parts; First expansion tape; an electrolyte contained in the housing; as well as an electrode assembly, comprising a first electrode piece, a second electrode piece, and a separator disposed between the first electrode piece and the second electrode piece, the electrode assembly being a wound structure wound around a winding central axis and disposed within the housing; The first electrode sheet includes a first section, which is the tail section of the first electrode sheet and is located at the outermost layer of the electrode assembly. The inner surface of the first section facing the winding center axis and the outer surface facing away from the winding center axis are both hollow foil areas. The first section includes a tail end. The bonding member bonds and fixes the tail end and extends beyond the tail end in the winding direction; The first expansion tape is bonded to the inner surface of the first section, and the outer surface of the first section is abutted against the shell to achieve electrical connection between the first electrode and the shell.

2. The electrochemical device according to claim 1, wherein The bonding member is a conductive adhesive film, and both the inner surface of the bonding member facing the winding central axis and the outer surface of the bonding member facing away from the winding central axis are conductive and electrically connected.

3. The electrochemical device according to any one of claims 1 to 2, wherein: The outermost side of the electrode assembly is the empty foil area of ​​the first pole piece.

4. The electrochemical device according to any one of claims 1 to 3, wherein: The inner surface of the outermost circle of the first pole piece facing the winding central axis is a hollow foil area, and the first expansion tape is adhered to the inner surface of the outermost circle of the first pole piece and wraps around the winding central axis.

5. The electrochemical device according to claim 4, wherein The shell is cylindrical, the electrode assembly is cylindrical, the electrode assembly also includes a pole ear, the second pole piece has a connection area, the connection area is connected to the pole ear, the first expansion tape has a first notch, and in the radial direction of the electrode assembly, the first notch corresponds to the connection area in a stacked manner.

6. The electrochemical device according to claim 5, wherein The first expansion tape has a second notch. In the radial direction of the electrode assembly, the second notch is stacked and corresponds to the connection area, and the second notch and the first notch are respectively located on two opposite sides of the connection area.

7. The electrochemical device according to any one of claims 1 to 6, wherein: The first pole piece further includes a second section, which is located at the secondary outer circle of the first pole piece. The second section is stacked and adjacent to the first section, and the second pole piece is not provided between the first section and the second section.

8. The electrochemical device according to claim 7, wherein The tail end of the isolation film is located between the first expansion tape and the second section.

9. The electrochemical device according to claim 8, wherein The first expansion tape is a single-sided tape, and in the winding direction, the tail end of the first expansion tape exceeds the tail end of the isolation film.

10. The electrochemical device according to any one of claims 1 to 9, wherein The shell is cylindrical, the electrode assembly is cylindrical, and the first expansion tape overlaps with the adhesive member in a radial direction of the electrode assembly.

11. The electrochemical device according to claim 10, wherein The bonding piece is a single-sided adhesive.

12. The electrochemical device according to claim 10 or 11, wherein In the winding direction, the tail end of the first pole piece exceeds the tail end of the first expansion tape.

13. The electrochemical device according to claim 12, wherein The adhesive member includes a first end and a second end spaced apart in the winding direction, the second end extending beyond the tail end of the first pole piece in the winding direction; in the winding direction, the distance between the first end and the tail end of the first pole piece is L, wherein the distance between the tail end of the first expansion tape and the tail end of the first pole piece is less than or equal to L / 2.

14. The electrochemical device according to any one of claims 1 to 11, wherein In the winding direction, the tail end of the first expansion tape exceeds the tail end of the first pole piece or the tail end of the first expansion tape is flush with the tail end of the first pole piece. The first pole piece also includes a third section, which is the head section of the first pole piece. The surface of the third section facing the winding center axis is a hollow foil area and is also bonded with a second expansion tape.

15. The electrochemical device according to any one of claims 1 to 14, wherein The electrode assembly has a central hole. Along the winding central axis, the projection of the winding central axis is located within the projection of the central hole. The electrochemical device further includes an insulating support member, which is at least partially disposed within the central hole.

16. The electrochemical device according to claim 15, wherein The insulating support member may be made of at least one of polypropylene and polyethylene.

17. The electrochemical device according to any one of claims 1 to 16, wherein: The first electrode sheet is a negative electrode sheet, the negative electrode sheet includes a negative electrode current collector, the negative electrode current collector is a copper foil, and the shell is a steel shell.

18. The electrochemical device according to claim 17, wherein The thickness of the first expansion tape is 10 μm to 50 μm. The negative electrode plate further includes a negative electrode active layer. The negative electrode active layer includes silicon material. The weight percentage of silicon in the negative electrode active layer is 3% to 100%.

19. The electrochemical device according to any one of claims 1 to 18, wherein The material of the first expansion tape includes at least one of polyisoprene, polybutadiene or thermoplastic polyurethane elastomer, and the material of the first expansion tape also includes at least one of acrylic glue, rubber or silicone.

20. The electrochemical device according to claim 2, wherein The conductive adhesive film comprises an adhesive layer matrix and a conductor, and the conductor is dispersed in the adhesive layer matrix.

21. The electrochemical device according to claim 20, wherein The adhesive layer matrix includes at least one of silicone rubber, polyurethane rubber, chloroprene rubber, hot melt adhesive or tackifying resin, and the conductor includes at least one of gold, silver, copper, aluminum, nickel or graphite.

22. An electronic device comprising a body, wherein: The electronic device further comprises an electrochemical device according to any one of claims 1 to 21, wherein the electrochemical device supplies power to the body.

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