Battery cell and electric equipment

Abstract

The invention provides a battery cell and electric equipment. The battery cell comprises a shell, an electrode assembly and a current collecting component, the electrode assembly is accommodated in the shell and comprises a main body part and a rubbing part connected with the main body part; the current collecting component is arranged in the shell, the rubbing part is arranged between the current collecting component and the main body part in the axial direction of the electrode assembly, and the current collecting component is electrically connected with the rubbing part; wherein the current collecting component comprises a first area welded with the rubbing part and a second area not welded with the rubbing part, the first area and the second area are not overlapped in the axial direction of the electrode assembly, the battery cell comprises a conductive layer, and the conductive layer is at least partially located between the second area and the rubbing part in the axial direction and is connected with the second area and the rubbing part. According to the present invention, the over-current capability and the connection stability between the current collecting member and the kneading part can be easily improved, the charge-discharge rate of the battery cell can be easily improved, the heat conduction and heat dissipation of the battery cell between the current collecting member and the kneading part can be easily achieved, the internal temperature rise can be reduced, and the safety performance of the battery cell can be easily improved.

Description

Technical Field

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

[0002] At present, with the rapid development of new energy technology, battery cells have been widely used in electronic equipment, electric vehicles, electric two-wheeled vehicles, power tools and other fields. As the application of battery cells becomes more and more extensive, higher requirements are placed on the safety performance of battery cells. Summary of the invention

[0003] The embodiments of the present application provide a battery cell and an electrical device to improve the safety performance of the battery cell.

[0004] In the first aspect, an embodiment of the present application provides a battery cell, the battery cell comprising a shell, an electrode assembly and a current collecting member; the electrode assembly is accommodated in the shell, the electrode assembly comprising a main body and a flattened portion connected to the main body; the current collecting member is arranged in the shell, along the axial direction of the electrode assembly, the flattened portion is arranged between the current collecting member and the main body, and the current collecting member is electrically connected to the flattened portion; wherein the current collecting member comprises a first area welded to the flattened portion and a second area not welded to the flattened portion, along the axial direction of the electrode assembly, the first area and the second area do not overlap, the battery cell also comprises a conductive layer, along the axial direction of the electrode assembly, the conductive layer is at least partially located between the second area and the flattened portion and connects the second area with the flattened portion.

[0005] In one or more optional embodiments above, the current collecting component includes a first area welded to the flattened portion and a second area not welded to the flattened portion, and the second area and the flattened portion are connected through a conductive layer, that is, the flattened portion and a partial area of ​​the current collecting component are welded, and the flattened portion and a partial area of ​​the current collecting component are connected through a conductive layer. Compared with the case where the flattened portion and the current collecting component are only connected by welding, the first area of ​​the current collecting component and the flattened portion are welded, and the second area of ​​the current collecting component and the flattened portion are connected through a conductive layer, which increases the connection area between the flattened portion and the current collecting component, is conducive to improving the current flow capacity and connection stability between the current collecting component and the flattened portion, is conducive to improving the charge and discharge rate of the battery cell, and improves the conductivity and safety performance of the battery cell. Compared with the case where the flattened portion and the current collecting component are only connected by welding, the welding area and the conductive layer between the current collecting component and the flattened portion are equivalent to forming two parallel current paths, which reduces the internal resistance of the battery cell and can reduce the internal consumption of the battery cell. In addition, a conductive layer is provided between the flattened portion and the current collecting member, which is also beneficial to heat conduction and heat dissipation of the battery cell between the current collecting member and the flattened portion, reduces the temperature rise inside the battery cell, and improves the safety performance of the battery cell.

[0006] In some embodiments of the first aspect of the present application, in a projection plane perpendicular to the axial direction of the electrode assembly, the area of ​​the overlapping region of the projection of the current collecting member and the projection of the flattened portion is S, and the sum of the areas of the projections of all the first regions is S. 1 , 0.1≤S 1 / S≤0.8.

[0007] In one or more optional embodiments above, the sum of the projection areas of all the first regions in the projection plane perpendicular to the axial direction of the electrode assembly is S 1 The ratio of the area S of the overlapping area between the projection of the current collecting member and the projection of the flattened portion is greater than or equal to 0.1, which is beneficial to improving the current carrying capacity and connection stability between the current collecting member and the flattened portion, improving the charge and discharge rate of the battery cell, improving the conductivity and safety performance of the battery cell, and reducing the connection area between the current collecting member and the conductive layer, so that the conductive layer occupies less space in the battery cell shell, which is beneficial to improving the energy density of the battery cell. By projecting the area S of the first region in the projection plane perpendicular to the axial direction of the electrode assembly 1 The ratio of the area S of the overlapping area of ​​the projection of the current collecting member and the projection of the flattened portion is less than or equal to 0.8, so that the second area of ​​the current collecting member has a sufficient area, and a sufficient area is reserved for the conductive layer to connect the second area and the flattened portion, which is beneficial to reducing the internal resistance of the battery cell, thereby reducing the internal friction of the battery cell, and is also beneficial to the heat conduction and heat dissipation of the battery cell between the current collecting member and the flattened portion, reducing the internal temperature rise of the battery cell, and improving the safety performance of the battery cell. Therefore, 0.1≤S 1 / S≤0.8, which not only makes the battery cell have a higher energy density, but also makes the battery cell have better safety performance.

[0008] In some embodiments of the first aspect of the present application, the thickness of the conductive layer is less than or equal to 1 mm.

[0009] In one or more of the above optional embodiments, the thickness of the conductive layer is less than or equal to 1 mm, so that the conductive part occupies less space inside the shell, which is conducive to the battery cell having a higher energy density.

[0010] In some embodiments of the first aspect of the present application, the first region is welded to the flattened portion to form a welding portion, the conductive layer includes a first part and a second part, and when observed along the axial direction of the electrode assembly, the projection of the first part is located in the first region, at least a portion of the first part is embedded in the welding portion, and the projection of the second part is located in the second region.

[0011] In one or more of the above optional embodiments, the projection of the first part of the conductive layer is located in the first area, and at least a part of the first part is embedded in the welding part, which is beneficial to filling the gap in the welding part, improving the connection stability between the current collecting component and the flattened part, and improving the conductivity between the current collecting component and the flattened part.

[0012] In some embodiments of the first aspect of the present application, a thickness of the second portion is greater than a thickness of the first portion.

[0013] In one or more of the above optional embodiments, the thickness of the second part connected to the flattened part by the conductive layer is greater than the thickness of the first part projected in the first area, so that the thickness of the second part can match the distance between the second area and the flattened part in the axial direction of the electrode assembly, so that the second area and the flattened part have better electrical connection stability, and the thickness of the first part can better adapt to the gap in the welding part, thereby better filling the gap in the welding part, improving the connection stability between the current collecting component and the flattened part and the conductivity between the current collecting component and the flattened part.

[0014] In some embodiments of the first aspect of the present application, the current collecting member includes a plurality of first regions and a plurality of second regions, and the first regions and the second regions are alternately arranged along the circumference of the electrode assembly.

[0015] In one or more of the above optional embodiments, the first region and the second region are alternately arranged along the circumference of the electrode assembly, so that the conductive layer and the welding part are alternately arranged along the circumference of the electrode assembly, so that the conductive layer and the welding part are evenly distributed, which is beneficial to improving the conductive performance of the battery cell and improving the uniformity of heat distribution between the flattened part and the current collecting component, and reducing the problem of reduced safety due to local excessive temperature.

[0016] In some embodiments of the first aspect of the present application, at least one of the first region and the second region is annular.

[0017] In one or more of the above optional embodiments, at least one of the first region and the second region is annular, so that the flattened portion and the current collecting member are conveniently electrically connected.

[0018] In some embodiments of the first aspect of the present application, the second region is annular and is arranged around the periphery of the first region.

[0019] In one or more of the above optional embodiments, the second area is arranged around the periphery of the first area, which facilitates the arrangement of a conductive layer between the second area and the flattened portion. The first area and the flattened portion can be welded first, and then the conductive layer is arranged between the second area and the flattened portion. This is beneficial to better stability of the conductive layer between the second area and the flattened portion. In an embodiment where the conductive layer is a conductive adhesive, it is also beneficial for the conductive adhesive to be embedded in the welding portion.

[0020] In some embodiments of the first aspect of the present application, the thermal conductivity of the conductive layer is 2W / (mK)-10W / (mK).

[0021] In one or more of the above optional embodiments, the thermal conductivity of the conductive layer is greater than or equal to 2W / (mK), so that the thermal conductivity of the conductive layer is better, which is beneficial to heat conduction and heat dissipation between the flattened portion and the current collecting structure, reducing the temperature rise inside the battery cell, and improving the safety performance of the battery cell. The thermal conductivity of the conductive layer is less than or equal to 10W / (mK), which is beneficial to reducing costs. Therefore, the thermal conductivity of the conductive layer is 2W / (mK)-10W / (mK), which can not only improve the safety performance of the battery cell, but also reduce the cost of the battery cell.

[0022] In some embodiments of the first aspect of the present application, the conductive layer includes a conductive glue.

[0023] In one or more of the above optional embodiments, the conductive adhesive has the advantages of good conductivity, easy processing, good thermomechanical properties, good aging resistance, and long service life. The conductive layer includes conductive parts, so that the conductive layer has good conductivity, thermomechanical properties, aging resistance, and long service life, thereby improving the conductivity of the battery cell and extending the service life of the battery cell.

[0024] In some embodiments of the first aspect of the present application, the conductive adhesive includes a conductive filler and an adhesive.

[0025] In one or more of the above optional embodiments, the conductive adhesive includes a conductive filler and an adhesive, so that the conductive adhesive has good conductive properties, and both the current collecting component and the flattened portion can be bonded to the conductive adhesive, thereby improving the electrical connection stability between the current collecting component and the conductive layer, and between the flattened portion and the conductive layer.

[0026] In some embodiments of the first aspect of the present application, the conductive filler includes at least one of gold, silver, copper, aluminum, zinc, iron, nickel, graphite, and a conductive polymer compound; the adhesive includes at least one of epoxy resin, silicone resin, polyimide resin, phenolic resin, polyurethane, and acrylic resin.

[0027] In one or more of the above optional embodiments, the conductive filler includes at least one of gold, silver, copper, aluminum, zinc, iron, nickel, graphite, and conductive polymer compounds, which is conducive to improving the conductive performance and heat dissipation capacity of the conductive layer. The adhesive includes at least one of epoxy resin, silicone resin, polyimide resin, phenolic resin, polyurethane, and acrylic resin, which is conducive to having good bonding ability between the conductive layer and the current collecting member, and between the flattened portion and the conductive layer, thereby improving the connection stability.

[0028] In some embodiments of the first aspect of the present application, the electrode assembly includes two flattened portions with opposite polarities, and along the axial direction of the electrode assembly, the two flattened portions are respectively located at opposite ends of the main body; the battery cell includes two current collecting components, each current collecting component is electrically connected to a flattened portion, the first area of ​​each current collecting component is welded to a flattened portion, and the second area of ​​each current collecting component is connected to a flattened portion through at least one conductive layer.

[0029] In one or more of the above optional embodiments, by welding the first area of ​​each current collecting component to a flattened portion, and connecting the second area of ​​each current collecting component to a flattened portion through at least one conductive layer, the charge and discharge rate of the battery cell can be further improved, the conductivity and safety performance of the battery cell can be improved, the internal resistance of the battery cell can be further reduced, the internal friction of the battery cell can be reduced, the internal temperature rise of the battery cell can be further reduced, and the safety performance of the battery cell can be improved.

[0030] In a second aspect, an embodiment of the present application provides an electrical device, comprising a battery cell provided by any embodiment of the first aspect.

[0031] In one or more of the above optional embodiments, the battery cell provided by any embodiment of the first aspect has good conductivity and safety performance, which is beneficial to improving the power reliability and power safety of electrical equipment powered by the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope.

[0033] Figure 1 A cross-sectional view of a battery cell provided in some embodiments of the present application;

[0034] Figure 2 A cross-sectional view of a battery cell provided in some other embodiments of the present application;

[0035] Figure 3 A cross-sectional view of a battery cell provided in some further embodiments of the present application;

[0036] Figure 4 A schematic diagram of the structure of an electrode assembly provided in some embodiments of the present application;

[0037] Figure 5 A schematic diagram of the structure of a positive electrode sheet provided in some embodiments of the present application (the positive electrode tab is a full-tab structure);

[0038] Figure 6 A schematic diagram of the structure of a positive electrode sheet provided in some other embodiments of the present application (the positive electrode tab is a split-type tab structure);

[0039] Figure 7 A schematic diagram of an electrode assembly and a current collecting member connected in some embodiments of the present application;

[0040] Figure 8 A view of the electrode assembly along the axial direction after the flattened portion and the current collecting member are matched according to some embodiments of the present application;

[0041] Fig. 9 A view of the electrode assembly along the axial direction after the flattened portion and the current collecting member are matched with each other in some other embodiments of the present application.

[0042] Icons: 100-battery cell; 10-casing; 11-shell; 111-opening; 12-cover; 20-electrode assembly; 21-positive electrode sheet; 22-negative electrode sheet; 23-separation membrane; 24-positive electrode tab; 25-negative electrode tab; 20a-main body; 20b-flattened portion; 30-electrode terminal; 40-current collecting member; 41-first region; 42-second region; 43-through hole; 50-conductive layer; 51-second part; X-axial direction of electrode assembly; Y-circumferential direction of electrode assembly; Q-welding portion; P-winding center hole. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0044] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application claimed for protection, but merely represents selected embodiments of the present application. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other without conflict.

[0045] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0046] In the description of the embodiments of the present application, it should be noted that the indicated orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the application is usually placed when in use, or the orientation or positional relationship commonly understood by those skilled in the art, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0047] At present, judging from the development of the market situation, the application of battery cells is becoming more and more extensive. Battery cells are widely used in electric vehicles such as electric bicycles, electric motorcycles, electric vehicles, as well as electric tools, drones, energy storage equipment and other fields. With the continuous expansion of the application field of battery cells, the market demand is also constantly expanding, and the requirements for battery cell safety are becoming higher and higher.

[0048] The battery cells include stacked battery cells and wound battery cells. For the wound battery cells, the pole ears of the electrode assemblies of the battery cells are flattened to form flattened parts, which are welded to the current collecting components through the flattened parts to lead out the electrodes. However, the flattened parts are formed by flattening, so that the connecting surface between the flattened parts and the current collecting components is not a plane but an uneven surface. The surfaces of the current collecting components and the flattened parts cannot be completely fitted together, resulting in poor electrical conductivity and thermal conductivity after the current collecting components are welded to the flattened parts, thereby reducing the safety performance of the battery cells.

[0049] Based on the above considerations, in order to improve the safety performance of the battery cell, an embodiment of the present application provides a battery cell, the battery cell includes a shell, an electrode assembly and a current collecting component; the electrode assembly is accommodated in the shell, and the electrode assembly includes a main body and a flattened portion connected to the main body; the current collecting component is arranged in the shell, and along the axial direction of the electrode assembly, the flattened portion is arranged between the current collecting component and the main body, and the current collecting component is electrically connected to the flattened portion; wherein the current collecting component includes a first area welded to the flattened portion and a second area not welded to the flattened portion, and along the axial direction of the electrode assembly, the first area and the second area do not overlap, and the battery cell also includes a conductive layer, and along the axial direction of the electrode assembly, the conductive layer is at least partially located between the second area and the flattened portion and connects the second area with the flattened portion.

[0050] The current collecting member includes a first area welded to the flattened portion and a second area not welded to the flattened portion, and the second area and the flattened portion are connected through a conductive layer, that is, the flattened portion and a part of the current collecting member are welded, and the flattened portion and a part of the current collecting member are connected through a conductive layer. Compared with the case where the flattened portion and the current collecting member are connected only by welding, the first area of ​​the current collecting member and the flattened portion are welded, and the second area of ​​the current collecting member and the flattened portion are connected through a conductive layer, which increases the connection area between the flattened portion and the current collecting member, is conducive to improving the current flow capacity and connection stability between the current collecting member and the flattened portion, is conducive to improving the charge and discharge rate of the battery cell, and improves the conductivity and safety performance of the battery cell. Compared with the case where the flattened portion and the current collecting member are connected only by welding, the welding area and the conductive layer are equivalent to forming two parallel current paths between the current collecting member and the flattened portion, which reduces the internal resistance of the battery cell and can reduce the internal consumption of the battery cell. In addition, a conductive layer is provided between the flattened portion and the current collecting member, which is also beneficial to heat conduction and heat dissipation of the battery cell between the current collecting member and the flattened portion, reduces the temperature rise inside the battery cell, and improves the safety performance of the battery cell.

[0051] The battery cell disclosed in the embodiment of the present application can be used in, but not limited to, electric two-wheeled vehicles, electric tools, drones, energy storage devices and other electrical equipment. The battery cell with the working condition of the present application can also be used as a power supply system for electrical equipment, which is conducive to improving the safety performance of the battery cell.

[0052] The embodiment of the present application provides an electric device using a battery cell as a power source, and the electric device may be, but is not limited to, electronic equipment, electric tools, electric vehicles, drones, and energy storage devices. Among them, electronic equipment may include mobile phones, tablets, laptops, etc., electric tools may include electric drills, electric saws, etc., and electric vehicles may include electric cars, electric motorcycles, electric bicycles, etc.

[0053] like Figure 1 , Figure 2 As shown, an embodiment of the present application provides a battery cell 100 , which includes a housing 10 and an electrode assembly 20 , wherein the electrode assembly 20 is accommodated in the housing 10 .

[0054] The housing 10 forms a storage space. The storage space can be used to store the electrode assembly 20, electrolyte, etc. The housing 10 can be a hard shell, such as a steel shell or an aluminum shell, forming a steel shell battery cell or an aluminum shell battery cell. The housing 10 can also be formed of a softer material, such as an aluminum-plastic film or a steel-plastic film, forming a soft-pack battery cell.

[0055] The housing 10 may include a shell 11 and a cover 12. The shell 11 has an opening 111 at at least one end. The cover 12 is used to cover the opening 111 of the shell 11, so that the shell 11 and the cover 12 define a receiving space together. Figure 1As shown, along the axial direction X of the electrode assembly, an opening 111 is formed at one end of the shell 11, and the shell 11 has a bottom wall opposite to the cover 12. The cover 12 is insulated and provided with an electrode terminal 30. The electrode terminal 30 can also be called a pole. Figure 2 , Figure 3 As shown, along the axial direction X of the electrode assembly, openings 111 are formed at both ends of the shell 11, and the outer shell 10 includes two covers 12, which respectively cover the two openings 111, and at least one of the two covers 12 is insulated and provided with an electrode terminal 30. Figure 2 FIG. 2 shows a case where both cover bodies 12 are insulated and provided with electrode terminals 30 . Figure 3 FIG. 2 shows a case where two end caps are insulated and provided with electrode terminals 30 .

[0056] like Figure 4 As shown, the electrode assembly 20 includes a separator 23 , a positive electrode sheet 21 , another separator 23 and a negative electrode sheet 22 .

[0057] The positive electrode sheet 21 includes a positive current collector and a positive active material layer. The positive active material layer is provided on at least one side of the positive current collector. For lithium-ion batteries, the material of the positive current collector may be aluminum. The positive active material layer may be lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganese oxide, etc. The positive current collector may be a composite current collector or a non-composite current collector.

[0058] The negative electrode sheet 22 includes a negative electrode current collector and a negative electrode active material layer. The negative electrode active material layer is provided on at least one side of the negative electrode current collector. For lithium-ion batteries, the material of the negative electrode current collector may be copper. The negative electrode current collector may be a composite current collector or a non-composite current collector. The negative electrode active material may be a carbon material or a silicon material, etc.

[0059] The separator 23 insulates and separates the positive electrode sheet 21 and the negative electrode sheet 22 to reduce the risk of short circuit of the battery cell 100. The material of the separator 23 may include polypropylene (PP) or polyethylene (PE).

[0060] The electrode assembly 20 is a wound structure. Specifically, the positive electrode sheet 21, the separator 23, the negative electrode sheet 22 and another separator 23 are stacked and then wound to form an electrode assembly 20 with a wound structure; or, the separator 23, the positive electrode sheet 21, another separator 23 and the negative electrode sheet 22 are stacked and then wound to form an electrode assembly 20 with a wound structure. The wound electrode assembly 20 can be a flat wound electrode assembly 20 or a cylindrical electrode assembly 20. In the embodiment where the electrode assembly 20 is a cylindrical structure, the battery cell 100 can be a cylindrical battery cell 100 or a columnar battery cell 100. Figure 1FIG. 4 shows a case where the battery cell 100 is a cylindrical battery cell. Figure 2 , the electrode assembly 20 is shown as a cylindrical structure.

[0061] The electrode assembly 20 further includes a positive electrode tab 24 and a negative electrode tab 25. The positive electrode tab 24 is electrically connected to the positive electrode sheet 21, and the negative electrode tab 25 is electrically connected to the negative electrode sheet 22. Along the axial direction X of the electrode assembly, the positive electrode tab 24 and the negative electrode tab 25 can be located at the same end of the electrode assembly 20, and the positive electrode tab 24 and the negative electrode tab 25 can also be located at opposite ends of the electrode assembly 20, respectively.

[0062] The electrode assembly 20 includes a main body 20a and a flattened portion 20b connected to the main body 20a. The electrode assembly 20 may include two flattened portions 20b, and the two flattened portions 20b have opposite polarities. Along the axial direction X of the electrode assembly, the two flattened portions 20b may be located at the same end of the main body 20a, or at two opposite ends of the main body 20a.

[0063] Among them, the positive electrode sheet 21, the negative electrode sheet 22 and the separator 23 are wound to form the main body 20a of the electrode assembly 20. The positive electrode tab 24 is formed into a flattened portion 20b by a flattening process. The negative electrode tab 25 is formed into another flattened portion 20b by a flattening process. If the positive electrode tab 24 and the negative electrode tab 25 are located at the same end of the electrode assembly 20, then along the axial direction X of the electrode assembly, the two flattened portions 20b are located at the same end of the main body 20a. If the positive electrode tab 24 and the negative electrode tab 25 are located at opposite ends of the electrode assembly 20, then along the axial direction X of the electrode assembly, the two flattened portions 20b are respectively located at opposite ends of the main body 20a.

[0064] The positive electrode tab 24 and the negative electrode tab 25 may be a full tab structure. The positive electrode tab 24 and the negative electrode tab 25 may also be a split tab structure formed by die-cutting a substrate. Figure 5 2 shows the case where the positive electrode tab 24 is a full tab. Figure 6 The structure of the full-tab negative electrode tab 25 can refer to the structure of the full-tab positive electrode tab 24, and the structure of the split-tab negative electrode tab 25 can refer to the structure of the split-tab positive electrode tab 24.

[0065] The battery cell 100 further includes a current collecting member 40 disposed in the housing 10 . Along the axial direction X of the electrode assembly, the flattened portion 20 b is disposed between the current collecting member 40 and the main body 20 a , and the current collecting member 40 is electrically connected to the flattened portion 20 b .

[0066] The battery cell 100 may include one current collecting member 40, and one of the two flattened portions 20b is connected to the one current collecting member 40. The other flattened portion 20b may be directly connected to other components, such as the housing 10.

[0067] In other embodiments, Figure 7 As shown, the battery cell 100 includes two current collecting members 40, each current collecting member 40 is electrically connected to one of the flattened portions 20b, and each current collecting member 40 is connected to one of the flattened portions 20b.

[0068] In an embodiment where the battery cell 100 includes a current collecting member 40, the housing 10 includes a housing 11 and a cover 12. Along the first direction, an opening 111 is formed at one end of the housing 11, and the cover 12 covers the opening 111. The cover 12 is provided with an electrode terminal 30, and the electrode terminal 30 is insulated and arranged on the cover 12. One flattened portion 20b can be electrically connected to the electrode terminal 30 through the current collecting member 40, and the other flattened portion 20b can be connected to the housing 10 (e.g., the housing 11). Figure 1 As shown, in an embodiment where the battery cell 100 includes two current collecting members 40 , one flattened portion 20 b may be electrically connected to the electrode terminal 30 through the current collecting member 40 , and the other flattened portion 20 b may be connected to the housing 10 (eg, the shell 11 ) through the other current collecting member 40 .

[0069] The housing 10 includes a shell 11 and two covers 12. Along a first direction, openings 111 are formed at opposite ends of the shell 11, and each cover 12 covers one opening 111. Figure 2 As shown, one cover 12 may be insulated and provided with an electrode terminal 30, while the other cover 12 may not be provided with an electrode terminal 30. In an embodiment where the battery cell 100 includes a current collecting member 40, one flattened portion 20b may be electrically connected to the electrode terminal 30 through the current collecting member 40, and the other flattened portion 20b may be connected to the housing 10 (e.g., the cover 12). Figure 2 As shown, in an embodiment where the battery cell 100 includes two current collecting members 40 , one flattened portion 20 b may be electrically connected to the electrode terminal 30 through the current collecting member 40 , and the other flattened portion 20 b may be connected to the housing 10 (eg, the cover 12 ) through another current collecting member 40 .

[0070] Of course, if Figure 3 As shown, both covers 12 may also be provided with electrode terminals 30 , which are insulated and arranged on the corresponding covers 12 , and the two flattened portions 20 b may be electrically connected to the electrode terminals 30 of the two covers 12 through two current collecting members 40 , respectively.

[0071] The current collecting member 40 includes a first region 41 welded to the flattened portion 20b and a second region 42 not welded to the flattened portion 20b, and along the axial direction X of the electrode assembly, the first region 41 and the second region 42 do not overlap, and the battery cell 100 also includes a conductive layer 50, and along the axial direction X of the electrode assembly, the conductive layer 50 is at least partially located between the second region 42 and the flattened portion 20b and connects the second region 42 and the flattened portion 20b.

[0072] The first region 41 and the flattened portion 20b may be welded by laser welding, ultrasonic welding, etc. The first region 41 and the flattened portion 20b are welded to form a welded portion Q.

[0073] The second region 42 and the flattened portion 20b are electrically connected via the conductive layer 50. The conductive layer 50 and the second region 42 may be in contact connection. The conductive layer 50 and the second region 42 may also be connected in a certain connection manner, such as an adhesive connection. The conductive layer 50 and the flattened portion 20b may be in contact connection. The conductive layer 50 and the flattened portion 20b may also be connected in a certain connection manner, such as an adhesive connection.

[0074] The conductive layer 50 may be partially located between the second region 42 and the flattened portion 20 b , or the conductive layer 50 may be entirely located between the second region 42 and the flattened portion 20 b .

[0075] The current collecting member 40 includes a first area 41 welded to the flattened portion 20b and a second area 42 not welded to the flattened portion 20b, the second area 42 and the flattened portion 20b are connected through the conductive layer 50, that is, the flattened portion 20b and a partial area of ​​the current collecting member 40 are welded, and the flattened portion 20b and a partial area of ​​the current collecting member 40 are connected through the conductive layer 50. Compared with the case where the flattened portion 20b and the current collecting member 40 are only connected by welding, the first area 41 of the current collecting member 40 is welded to the flattened portion 20b, and the second area 42 of the current collecting member 40 is connected to the flattened portion 20b through the conductive layer 50, which increases the connection area between the flattened portion 20b and the current collecting member 40, which is beneficial to improving the current passing capacity and connection stability between the current collecting member 40 and the flattened portion 20b, and is beneficial to improving the charge and discharge rate of the battery cell 100, and improving the conductivity and safety performance of the battery cell 100. Compared with the case where the flattened portion 20b and the current collecting member 40 are connected only by welding, the welding area and the conductive layer 50 form two parallel current paths between the current collecting member 40 and the flattened portion 20b, which reduces the internal resistance of the battery cell 100 and can reduce the internal friction of the battery cell 100. In addition, the conductive layer 50 is arranged between the flattened portion 20b and the current collecting member 40, which is also beneficial to the heat conduction and heat dissipation of the battery cell 100 between the current collecting member 40 and the flattened portion 20b, reduces the internal temperature rise of the battery cell 100, and improves the safety performance of the battery cell 100.

[0076] like Figure 7As shown, the electrode assembly 20 includes two flattened portions 20b with opposite polarities, and along the axial direction X of the electrode assembly, the two flattened portions 20b are respectively located at opposite ends of the main body 20a; the battery cell 100 includes two current collecting components 40, each current collecting component 40 is electrically connected to a flattened portion 20b, the first area 41 of each current collecting component 40 is welded to a flattened portion 20b, and the second area 42 of each current collecting component 40 is connected to a flattened portion 20b through at least one conductive layer 50.

[0077] By welding the first area 41 of each current collecting component 40 to a flattened portion 20 b, and connecting the second area 42 of each current collecting component 40 to a flattened portion 20 b through at least one conductive layer 50, the charge and discharge rate of the battery cell 100 can be further improved, the conductivity and safety performance of the battery cell 100 can be improved, the internal resistance of the battery cell 100 can be further reduced, the internal friction of the battery cell 100 can be reduced, the internal temperature rise of the battery cell 100 can be further reduced, and the safety performance of the battery cell 100 can be improved.

[0078] In some embodiments, in the projection plane perpendicular to the axial direction X of the electrode assembly, the area of ​​the overlapping region of the projection of the current collecting member 40 and the projection of the flattened portion 20b is S, and the sum of the projection areas of all the first regions 41 is S. 1 , 0.1≤S 1 / S≤0.8.

[0079] In the projection plane perpendicular to the axial direction X of the electrode assembly, the projection area of ​​the current collecting member 40 may be greater than, less than, or equal to the projection area of ​​the flattened portion 20b. In the embodiment where the projection area of ​​the current collecting member 40 is smaller than the projection area of ​​the flattened portion 20b, the projection of the current collecting member 40 may be completely within the projection range of the flattened portion 20b, and the projection area of ​​the current collecting member 40 is S. In the embodiment where the projection area of ​​the current collecting member 40 is larger than the projection area of ​​the flattened portion 20b, the projection of the flattened portion 20b may be completely within the projection range of the current collecting member 40, and the projection area of ​​the flattened portion 20b is S.

[0080] For example, S 1 / S can be 0.1, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, etc.

[0081] The projection area S of the first region 41 is in the projection plane perpendicular to the axial direction X of the electrode assembly. 1The ratio of the area S of the overlapping area between the projection of the current collecting member 40 and the projection of the flattened portion 20b is greater than or equal to 0.1, which is beneficial to improving the current carrying capacity and connection stability between the current collecting member 40 and the flattened portion 20b, and is beneficial to improving the charge and discharge rate of the battery 100, improving the conductivity and safety performance of the battery 100, and can also reduce the connection area between the current collecting member 40 and the conductive layer 50, so that the conductive layer 50 occupies less space in the battery cell 100 housing 10, which is beneficial to improving the energy density of the battery 100. By in the projection plane perpendicular to the axial direction X of the electrode assembly, the projection area S of the first region 41 is 1 The ratio of the area S of the overlapping area of ​​the projection of the current collecting member 40 and the projection of the flattened portion 20b is less than or equal to 0.8, so that the second area 42 of the current collecting member 40 has a sufficient area, and a sufficient area is reserved for the conductive layer 50 to connect the second area 42 and the flattened portion 20b, which is beneficial to reducing the internal resistance of the battery cell 100, thereby reducing the internal friction of the battery cell 100, and is also beneficial to the heat conduction and heat dissipation of the battery cell 100 between the current collecting member 40 and the flattened portion 20b, reducing the internal temperature rise of the battery cell 100, and improving the safety performance of the battery cell 100. Therefore, 0.1≤S 1 / S≤0.8, which not only enables the battery cell 100 to have a higher energy density, but also enables the battery cell 100 to have better safety performance.

[0082] In some embodiments, the thickness of conductive layer 50 is less than or equal to 1 mm.

[0083] The thickness of the conductive layer 50 may be the dimension of the conductive layer 50 in the thickness direction of the electrode assembly 20. The thickness of the conductive layer 50 at any position is less than or equal to 1 mm. Figure 7 As shown, the thickness of the conductive layer 50 is H, where H≤1 mm.

[0084] The conductive layer 50 may be a structure of uniform thickness, that is, the thickness of any position of the conductive layer 50 is the same.

[0085] The conductive layer 50 may also be a non-uniform thickness structure, that is, the thicknesses of at least two locations of the conductive layer 50 are different.

[0086] Illustratively, the thickness of the conductive layer 50 may be 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, etc.

[0087] The thickness of the conductive layer 50 is less than or equal to 1 mm, so that the conductive component occupies less space inside the housing 10 , which is beneficial for the battery cell 100 to have a higher energy density.

[0088] like Figure 7As shown, in some embodiments, the first region 41 is welded to the flattened portion 20b to form a welding portion Q, and the conductive layer 50 includes a first part (not shown in the figure) and a second part 51. When observed along the axial direction X of the electrode assembly, the projection of the first part is located in the first region 41, at least a portion of the first part is embedded in the welding portion Q, and the projection of the second part 51 is located in the second region 42.

[0089] The projection of the second portion 51 is located in the second region 42 , and the second portion 51 connects the second region 42 and the flattened portion 20 b .

[0090] The projection of the first part of the conductive layer 50 is located in the first area 41, and at least a part of the first part is embedded in the welding portion Q, which is beneficial to filling the gap of the welding portion Q, improving the connection stability between the current collecting component 40 and the flattened portion 20b and the conductivity between the current collecting component 40 and the flattened portion 20b.

[0091] In some embodiments, the thickness of the second portion 51 is greater than the thickness of the first portion, that is, the conductive layer 50 has a non-uniform thickness structure.

[0092] The thickness of the second part 51 connecting the second part 51 and the flattened portion 20b through the conductive layer 50 is greater than the first part projected on the first area 41, so that the thickness of the second part 51 can match the distance between the second area 42 and the flattened portion 20b in the axial direction X of the electrode assembly, so that the second area 42 and the flattened portion 20b have better electrical connection stability, and the thickness of the first part can better adapt to the gap in the welding portion Q, thereby better filling the gap in the welding portion Q, improving the connection stability between the current collecting component 40 and the flattened portion 20b and the conductivity between the current collecting component 40 and the flattened portion 20b.

[0093] There are many ways to arrange the first area 41 and the second area 42. For example, Figure 8 As shown, in some embodiments, the current collecting member 40 includes a plurality of first regions 41 and a plurality of second regions 42 , and along the circumferential direction Y of the electrode assembly, the first regions 41 and the second regions 42 are alternately arranged.

[0094] In the embodiment where the current collecting member 40 includes a plurality of first regions 41, S 1 It should be the sum of the projected areas of all first regions 41 in the axial direction X perpendicular to the electrode assembly.

[0095] The shape of the first region 41 and the shape of the second region 42 can be various, for example, the shape of the first region 41 and the shape of the second region 42 can be circular, rectangular, elliptical, triangular, etc. Figure 8As shown, the shape of the first region 41 and the shape of the second region 42 may be fan-shaped. The central angle corresponding to the first region 41 and the central angle corresponding to the second region 42 may be the same or different. The current collecting member 40 has a through hole 43 corresponding to the winding center hole P of the electrode assembly 20, and the first region 41 and the second region 42 are alternately arranged around the through hole 43.

[0096] Along the circumferential direction Y of the electrode assembly, the first regions 41 and the second regions 42 are alternately arranged, which means that along the circumferential direction Y of the electrode assembly, a second region 42 is arranged between two adjacent first regions 41, a first region 41 is arranged between two adjacent second regions 42, and the adjacent first regions 41 and second regions 42 are connected.

[0097] By alternately arranging the first region 41 and the second region 42 along the circumferential direction Y of the electrode assembly, the conductive layer 50 and the welding portion Q are alternately arranged along the circumferential direction Y of the electrode assembly, so that the conductive layer 50 and the welding portion Q are evenly distributed, which is beneficial to improving the conductive performance of the battery cell 100 and improving the uniformity of heat distribution between the flattened portion 20b and the current collecting component 40, and reducing the problem of reduced safety due to local excessive temperature.

[0098] In some other embodiments, at least one of the first region 41 and the second region 42 is annular.

[0099] The first region 41 may be annular, the second region 42 may be annular, or both the first region 41 and the second region 42 may be annular. Fig. 9 As shown, the first region 41 and the second region 42 are both annular, and the first region 41 and the second region 42 are both arranged around the winding center hole P of the electrode assembly 20 .

[0100] Since at least one of the first region 41 and the second region 42 is annular, electrical connection between the flattened portion 20 b and the current collecting member 40 is facilitated.

[0101] Furthermore, if Fig. 9 As shown, the second area 42 is annular and is arranged around the outer periphery of the first area 41 .

[0102] Along the radial direction of the electrode assembly 20 , the outer edge of the second region 42 is the outer edge of the current collecting member 40 , and the inner edge of the second region 42 is connected to the outer edge of the first region 41 .

[0103] By surrounding the second area 42 on the periphery of the first area 41, it is convenient to set the conductive layer 50 between the second area 42 and the flattened portion 20b, and the first area 41 and the flattened portion 20b can be welded first, and then the conductive layer 50 is set between the second area 42 and the flattened portion 20b, which is beneficial to better stability of the conductive layer 50 between the second area 42 and the flattened portion 20b. In the embodiment where the conductive layer 50 is a conductive adhesive, it is also beneficial for the conductive adhesive to be embedded in the welding portion Q.

[0104] Of course, in other embodiments, the first region 41 may also be annular, and the first region 41 is disposed around the outer periphery of the second region 42 .

[0105] In some embodiments, the thermal conductivity of the conductive layer 50 is 2 W / (mK)-10 W / (mK).

[0106] The thermal conductivity is a physical quantity that measures the thermal conductivity of the conductive layer 50 . The larger the value, the better the thermal conductivity of the conductive layer 50 . Conversely, the smaller the value, the worse the thermal conductivity of the conductive layer 50 .

[0107] The thermal conductivity of the conductive layer 50 can be 2W / (mK), 2.5W / (mK), 3W / (mK), 3.5W / (mK), 4W / (mK), 4.5W / (mK), 5W / (mK), 5.5W / (mK), 6W / (mK), 6.5W / (mK), 7.5W / (mK), 8W / (mK), 8.5W / (mK), 9W / (mK), 9.5W / (mK), 10W / (mK), etc.

[0108] The thermal conductivity of the conductive layer 50 is greater than or equal to 2W / (mK), so that the thermal conductivity of the conductive layer 50 is better, which is beneficial to heat dissipation between the flattened portion 20b and the current collector, reducing the temperature rise inside the battery cell 100, and improving the safety performance of the battery cell 100. The thermal conductivity of the conductive layer 50 is less than or equal to 10W / (mK), which is beneficial to reducing costs. Therefore, the thermal conductivity of the conductive layer 50 is 2W / (mK)-10W / (mK), which can not only improve the safety performance of the battery cell 100, but also reduce the cost of the battery cell 100.

[0109] In some embodiments, the conductive layer 50 includes a conductive glue.

[0110] Conductive glue is an adhesive with a certain conductivity after curing or drying. The conductive glue can be bonded to the flattened portion 20b, and the conductive glue can be bonded to the current collecting member 40, which can improve the electrical connection stability between the flattened portion 20b and the current collecting member 40. The conductive glue has fluidity before curing or drying. The conductive glue before curing or drying is filled between the second area 42 and the flattened portion 20b. Relying on its fluidity, the conductive glue can fully fill the pores between the current collecting member 40 and the flattened portion 20b, such as filling it into the gap of the welding portion Q, so that when observing along the axial direction X of the electrode assembly, a part of the conductive glue is projected in the second area 42, and a part of the conductive glue is projected in the first area 41 and embedded in the gap of the welding portion Q.

[0111] The conductive adhesive has the advantages of good conductivity, easy processing, good thermomechanical properties, good aging resistance, and long service life. The conductive layer 50 includes conductive parts, so that the conductive layer 50 has good conductivity, thermomechanical properties, aging resistance, and long service life, thereby improving the conductive performance of the battery cell 100 and extending the service life of the battery cell 100.

[0112] In some embodiments, the conductive adhesive includes a conductive filler and an adhesive. The adhesive and the conductive filler are mixed to form the conductive adhesive. The conductive adhesive includes the conductive filler and the adhesive, so that the conductive adhesive has good conductivity, and both the current collecting member 40 and the flattened portion 20b can be bonded to the conductive adhesive, thereby improving the electrical connection stability between the current collecting member 40 and the conductive layer 50, and between the flattened portion 20b and the conductive layer 50.

[0113] In some embodiments, the conductive filler includes at least one of gold, silver, copper, aluminum, zinc, iron, nickel, graphite, and a conductive polymer compound. The conductive filler may be one or more of gold, silver, copper, aluminum, zinc, iron, nickel, graphite, and a conductive polymer compound. The conductive filler includes at least one of gold, silver, copper, aluminum, zinc, iron, nickel, graphite, and a conductive polymer compound, which is beneficial to improving the conductive performance and heat conduction and heat dissipation capabilities of the conductive layer 50.

[0114] The adhesive includes at least one of epoxy resin, silicone resin, polyimide resin, phenolic resin, polyurethane, and acrylic resin.

[0115] One of epoxy resin, silicone resin, polyimide resin, phenolic resin, polyurethane, and acrylic resin forms the adhesive, or multiple of epoxy resin, silicone resin, polyimide resin, phenolic resin, polyurethane, and acrylic resin form the adhesive together.

[0116] The adhesive includes at least one of epoxy resin, silicone resin, polyimide resin, phenolic resin, polyurethane, and acrylic resin, which is beneficial for better bonding between the conductive layer 50 and the current collecting member 40, and between the flattened portion 20b and the conductive layer 50, thereby improving connection stability.

[0117] An embodiment of the present application further provides an electrical device, and the electrical device includes the battery cell 100 provided in any of the above embodiments.

[0118] The battery cell 100 provides electrical energy to electrical equipment.

[0119] The battery cell 100 provided in any of the above-mentioned embodiments has good conductivity and safety performance, which is beneficial to improving the power reliability and power safety of the electrical equipment powered by the battery cell 100 .

[0120] AC internal resistance test of battery cell:

[0121] At 25°C, an AC signal of 1kHz was applied to the battery cell, and the AC internal resistance of the battery cell was measured using an internal resistance meter.

[0122] 50% SOC DCR test:

[0123] At 25°C, let the battery stand for 10 minutes, then charge it to 4.3V at 0.2C constant current, and charge it to 0.05C at 4.3V constant voltage; after standing for 60 minutes, discharge it to 50% SOC at 0.2C constant current; after standing for 60 minutes, record the voltage V1; then discharge it at 1C constant current for 30 seconds, and record the voltage V2;

[0124] DCR = current corresponding to (V1-V2) / 1C.

[0125] Tensile strength test of flattened part and current collecting component:

[0126] At 25°C, the battery cells were disassembled to obtain an electrode assembly connected with a current collecting component. One end of the electrode assembly was fixed on one end of a high-speed rail tensile testing machine along the axial direction of the electrode assembly. The current collecting component was pulled at a speed of 20 mm / min using a high-speed rail tensile testing machine Al-7000. The force when the current collecting component and the flattened part of the electrode assembly were pulled apart was recorded, which was the breaking force.

[0127] By comparing the battery cell 100 in which the current collecting member 40 and the flattened portion 20 b are connected only by welding (Comparative Example 1) and the battery cell 100 in which the current collecting member 40 and the flattened portion 20 b are connected by welding and also by the conductive layer 50 (Examples 2-6), the data in Table 1 are obtained:

[0128] Table 1

[0129]

[0130] The difference between the battery cells 100 in Comparative Example 1 and Examples 1 to 6 is that:

[0131] Comparative Example 1:

[0132] The flattened portion 20 b and the current collecting member 40 are connected only by welding.

[0133] Embodiment 1:

[0134] In the electrode assembly 20, only the positive electrode flattened portion 20b and the current collecting component 40 are connected by welding and by conductive glue. The positive electrode flattened portion 20b and the current collecting component 40 are only connected by welding glue. The adhesive material of the conductive glue is epoxy resin, and the conductive and thermal conductive filler is Al powder particles with a particle size of 0.5μm and a filler solid content of 50%.

[0135] Embodiment 2:

[0136] The positive electrode flattened portion 20b of the electrode assembly 20 and the current collecting member 40 are both welded and connected by conductive glue, and the negative electrode flattened portion 20b of the electrode assembly 20 and the current collecting member 40 are both welded and connected by conductive glue. The adhesive material is epoxy resin, the conductive and thermally conductive filler is Al powder particles, the particle size is 0.5μm, and the solid content of the conductive and thermally conductive filler is 50%. The material of the adhesive for the conductive glue set on the negative electrode side is epoxy resin, the conductive and thermally conductive filler is Cu powder particles, the particle size is 0.5μm, and the solid content of the conductive and thermally conductive filler is 50%.

[0137] Embodiment 3:

[0138] The positive electrode flattened portion 20b of the electrode assembly 20 and the current collecting member 40 are connected by welding and by conductive adhesive. The adhesive material of the conductive adhesive on the positive electrode side is epoxy resin, and the conductive and thermal conductive filler is Al powder particles with a particle size of 0.3 μm and a filler solid content of 75%. The negative electrode flattened portion 20b of the electrode assembly 20 and the current collecting member 40 are connected by welding and by conductive adhesive. The binder of the conductive adhesive on the negative electrode side is epoxy resin, and the conductive and thermal conductive filler is Cu powder particles with a particle size of 0.3 μm and a conductive and thermal conductive filler solid content of 75%.

[0139] Embodiment 4:

[0140] The positive electrode flattened portion 20b of the electrode assembly 20 and the current collecting member 40 are connected by welding and by conductive adhesive. The adhesive of the conductive adhesive set on the positive electrode side is epoxy resin, and the conductive and thermal conductive filler is Al powder particles with a particle size of 0.3μm and a conductive and thermal conductive filler solid content of 90%. The negative electrode flattened portion 20b of the electrode assembly 20 and the current collecting member 40 are connected by welding and by conductive adhesive. The adhesive of the conductive adhesive on the negative electrode side is epoxy resin, and the conductive and thermal conductive filler is Cu powder particles with a particle size of 0.3μm and a conductive and thermal conductive filler solid content of 90%.

[0141] Embodiment 5:

[0142] The positive electrode flattened portion 20b of the electrode assembly 20 and the current collecting member 40 are connected by welding and by conductive adhesive. The adhesive of the conductive adhesive set on the positive electrode side is epoxy resin, and the conductive and thermal conductive filler is graphite particles with a particle size of 0.3 μm and a filler solid content of 50%. The negative electrode flattened portion 20b of the electrode assembly 20 and the current collecting member 40 are connected by welding and by conductive adhesive. The adhesive of the conductive adhesive on the negative electrode side is epoxy resin, and the conductive and thermal conductive filler is graphite particles with a particle size of 0.3 μm and a filler solid content of 50%.

[0143] Embodiment 6:

[0144] The positive electrode flattened portion 20b of the electrode assembly 20 and the current collecting member 40 are connected by welding and by conductive adhesive. The adhesive of the conductive adhesive set on the positive electrode side is epoxy resin, and the conductive and thermal conductive filler is graphene particles with a particle size of 0.3 μm and a filler solid content of 50%. The negative electrode flattened portion 20b of the electrode assembly 20 and the current collecting member 40 are connected by welding and by conductive adhesive. The adhesive of the conductive adhesive on the negative electrode side is epoxy resin, and the conductive and thermal conductive filler is graphene particles with a particle size of 0.3 μm and a filler solid content of 50%.

[0145] Embodiment 7:

[0146] The positive electrode flattened portion 20b of the electrode assembly 20 and the current collecting member 40 are connected by welding and by conductive adhesive. The adhesive of the conductive adhesive set on the positive electrode side is epoxy resin, and the conductive and thermal conductive filler is poly 3,4-ethylenedioxythiophene, and the solid content of the filler is 50%. The negative electrode flattened portion 20b of the electrode assembly 20 and the current collecting member 40 are connected by welding and by conductive adhesive. The adhesive of the conductive adhesive on the negative electrode side is epoxy resin, and the conductive and thermal conductive filler is poly 3,4-ethylenedioxythiophene, and the solid content of the filler is 50%.

[0147] As can be seen from Table 1, from Comparative Example 1 and Examples 2-6, the flattened portion 20b and the current collecting member 40 are connected through the conductive layer 50 and the battery cell 100 connected by welding, compared with the battery cell 100 in which the flattened portion 20b and the current collecting member 40 are only connected by welding, the internal resistance of the battery cell 100 is reduced, and the heat generation of the battery cell 100 can be reduced. Moreover, the flattened portion 20b and the current collecting member 40 are connected through the conductive layer 50 and the battery cell 100 connected by welding, compared with the battery cell 100 in which the flattened portion 20b and the current collecting member 40 are only connected by welding (under the same welding area), the breaking force between the current collecting member 40 and the flattened portion 20b is increased, that is, the connection strength between the current collecting member 40 and the flattened portion 20b is better.

[0148] It can be seen from Examples 2-6 that as long as the current collecting component 40 and the flattened portion 20b are connected via the conductive layer 50 and welding, the breaking force between the current collecting component 40 and the flattened portion 20b is substantially the same even if the material and component content of the conductive adhesive are changed.

[0149] It can be seen from Examples 2 to 4 that as the content of the conductive and thermally conductive filler increases, the internal resistance of the battery cell 100 increases first and then decreases.

[0150] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and changes.

Claims

1. A battery cell, characterized in that: include: shell; An electrode assembly is contained in the housing, and includes a main body and a flattened portion connected to the main body; as well as A current collecting member is disposed in the housing, along the axial direction of the electrode assembly, the flattened portion is disposed between the current collecting member and the main body, and the current collecting member is electrically connected to the flattened portion; In which, the current collecting component includes a first area welded to the flattened portion and a second area not welded to the flattened portion, and along the axial direction of the electrode assembly, the first area and the second area do not overlap, and the battery cell also includes a conductive layer, and along the axial direction of the electrode assembly, the conductive layer is at least partially located between the second area and the flattened portion and connects the second area with the flattened portion.

2. The battery cell according to claim 1, characterized in that: In a projection plane perpendicular to the axial direction of the electrode assembly, an overlapping area of ​​the projection of the current collecting member and the projection of the flattened portion is S, a sum of the projection areas of all the first regions is S1, and 0.1≤S1 / S≤0.

8.

3. The battery cell according to claim 1 or 2, characterized in that: The thickness of the conductive layer is less than or equal to 1 mm.

4. The battery cell according to any one of claims 1 to 3, characterized in that: The first region is welded to the flattened portion to form a welding portion, the conductive layer includes a first part and a second part, and when observed along the axial direction of the electrode assembly, the projection of the first part is located in the first region, at least a part of the first part is embedded in the welding portion, and the projection of the second part is located in the second region.

5. The battery cell according to claim 4, characterized in that: The thickness of the second portion is greater than the thickness of the first portion.

6. The battery cell according to any one of claims 1 to 5, characterized in that: The current collecting member includes a plurality of the first regions and a plurality of the second regions, and the first regions and the second regions are alternately arranged along a circumferential direction of the electrode assembly.

7. The battery cell according to any one of claims 1 to 5, characterized in that: At least one of the first region and the second region is annular.

8. The battery cell according to claim 7, characterized in that: The second area is annular and is arranged around the outer periphery of the first area.

9. The battery cell according to any one of claims 1 to 8, characterized in that: The thermal conductivity of the conductive layer is 2W / (mK)-10W / (mK).

10. The battery cell according to any one of claims 1 to 9, characterized in that: The conductive layer includes conductive glue.

11. The battery cell according to claim 10, characterized in that: The conductive adhesive comprises a conductive filler and an adhesive.

12. The battery cell according to claim 11, characterized in that: The conductive filler includes at least one of gold, silver, copper, aluminum, zinc, iron, nickel, graphite, and a conductive polymer compound; The adhesive includes at least one of epoxy resin, silicone resin, polyimide resin, phenolic resin, polyurethane, and acrylic resin.

13. The battery cell according to any one of claims 1 to 12, characterized in that: The electrode assembly comprises two kneaded flat parts with opposite polarities, and along the axial direction of the electrode assembly, the two kneaded flat parts are respectively located at two opposite ends of the main body; The battery core includes two current collecting members, each of which is electrically connected to one of the flattened portions, the first region of each current collecting member is welded to one of the flattened portions, and the second region of each current collecting member is connected to one of the flattened portions through at least one conductive layer.

14. An electrical device, characterized in that: Comprising a battery cell according to any one of claims 1 to 13.

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