Secondary battery and electronic device

Abstract

The present application relates to the technical field of batteries, and discloses a secondary battery and an electronic device. The secondary battery comprises a case, an electrode assembly, and a conductive terminal. A first electrode sheet of the electrode assembly comprises a first sub-electrode sheet, the first sub-electrode sheet is located at the outermost side in the thickness direction of the electrode assembly, the surface of the first sub-electrode sheet away from a second electrode sheet is provided with an empty foil region, and the empty foil region is electrically connected to the case. The conductive terminal is insulatedly arranged on the case, and the second electrode sheet of the electrode assembly comprises a tab electrically connected to the conductive terminal. The first electrode sheet comprises a first main body portion and a first extension portion, and the projection of the first extension portion in the thickness direction does not coincide with the tab and the conductive terminal. In the secondary battery, the empty foil region is provided on the surface of the first electrode sheet, and the empty foil region is in contact with the case to form an electrical connection, thereby improving the stability of the connection between the first electrode sheet and the case and reducing the number of conductive terminals. The first electrode sheet is further provided with the first extension portion to increase a coating space of an active material layer, thereby improving the energy density of the secondary battery.

Description

Secondary battery and electronic device

[0001] Cross-reference to Related Applications

[0002] This application claims priority to the Chinese Patent Application No. 202510292786.7, filed on March 12, 2025, and entitled "Secondary battery and electronic device", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] Embodiments of the present application relate to the technical field of battery, and particularly relate to a secondary battery and an electronic device. BACKGROUND

[0004] The existing secondary batteries have the problems of unstable internal structure and low energy density. With the rapid development of new energy technology, secondary batteries have been widely used in mobile phones, tablets, notebook computers, electric vehicles and other fields. The requirements for the quality safety and energy density of secondary batteries are also increasing.

[0005] SUMMARY

[0006] Embodiments of the present application provide a secondary battery and an electronic device, which can improve the structural stability of the secondary battery and improve the energy density of the secondary battery.

[0007] One technical solution adopted by the embodiments of the present application is to provide a secondary battery, which comprises a shell, an electrode assembly and a conductive terminal. The shell is provided with a receiving cavity. The electrode assembly comprises a first pole piece, a second pole piece and a separator, the first pole piece and the second pole piece are arranged alternately in sequence, and the separator is arranged between adjacent first pole pieces and second pole pieces. The first pole piece comprises a first sub-pole piece, the first sub-pole piece is located at the outermost side in the thickness direction of the electrode assembly, and the surface of the first sub-pole piece away from the second pole piece is provided with a hollow foil area, and the hollow foil area is electrically connected with the shell. The conductive terminal is insulated and arranged in the shell, and part of the conductive terminal extends out of the shell, and part of the conductive terminal is located in the receiving cavity. The second pole piece comprises a tab, and the tab is electrically connected with the conductive terminal. Along the length direction of the electrode assembly, the first pole piece comprises a first main body part and a first extension part, along the thickness direction of the electrode assembly, the projection of the first extension part does not overlap with the tab and the conductive terminal, and the length direction of the electrode assembly is perpendicular to the thickness direction of the electrode assembly. The conductive terminal extending out of the shell is to expose the conductive terminal out of the shell to facilitate electrical connection with the external circuit. In terms of height, the conductive terminal can exceed the outer surface of the shell or not exceed the outer surface, such as being flush with the outer surface of the shell or being lower than the outer surface of the shell. The secondary battery of the present application is provided with a hollow foil area on the surface of the first pole piece, the hollow foil area is in contact with the shell to form an electrical connection, which can improve the stability of the connection between the first pole piece and the shell, reduce the number of conductive terminals, release more space in the receiving cavity, increase the first extension part of the first pole piece to increase the coating space of the active material layer, and further improve the energy density of the secondary battery.

[0008] In some embodiments, the first pole piece further comprises at least one second sub-pole piece. The first sub-pole piece and the second sub-pole piece are independent of each other and are electrically connected after being stacked in the thickness direction of the electrode assembly, or the first pole piece is integrally formed and is formed into the first sub-pole piece and the second sub-pole piece after being continuously folded.

[0009] In some embodiments, the surfaces of the first sub-pole piece away from the second pole piece are all hollow foil areas, so as to increase the contact area between the first pole piece and the shell, increase the transmission path of the current, and further reduce the impedance to reduce the energy consumption.

[0010] In some embodiments, the secondary battery comprises conductive glue, the conductive glue is arranged between the hollow foil area and the shell, and the conductive glue electrically connects the hollow foil area and the shell. The conductive glue helps to fill the small gap between the hollow foil area and the shell, so as to enhance the stability and conductivity of the connection between the two.

[0011] In some embodiments, the hollow foil area is provided with a conductive protrusion, and the conductive protrusion electrically connects the hollow foil area and the shell. The conductive protrusion helps to improve the conductivity between the first pole piece and the shell.

[0012] In some embodiments, the second tab further comprises a second main portion and a second extension portion along the length direction of the electrode assembly, and the tab is connected to the second main portion. The projection of the first extension portion covers the projection of the second extension portion along the thickness direction of the electrode assembly. The first tab is directly electrically connected to the shell without the need of the adapter terminal, which releases more space in the accommodation cavity. The first tab can increase the first extension portion to increase the space for coating the active material layer of the first tab, and the second tab can increase the second extension portion to increase the space for coating the active material layer of the second tab, thereby improving the energy density of the secondary battery.

[0013] In some embodiments, the first tab comprises two first sub tabs, and the two first sub tabs are respectively arranged at the two outermost sides in the thickness direction of the electrode assembly, which can increase the contact area between the first tab and the shell, increase the current transmission path, further reduce the impedance to reduce the energy consumption, and additionally reduce the insulation requirement between the second tab and the shell.

[0014] In some embodiments, the empty foil area comprises a first area and a second area, the first area is located on the surface of one of the first sub tabs away from the second tab, and the second area is located on the surface of the other first sub tab away from the second tab, so that the first area and the second area are respectively located at the two outermost sides in the thickness direction of the electrode assembly. The electrode assembly further comprises a conductive member, and the conductive member comprises a first conductive layer and a second conductive layer. The first conductive layer is arranged between the first area and the shell and electrically connects the first area and the shell, and the second conductive layer is arranged between the second area and the shell and electrically connects the second area and the shell.

[0015] In some embodiments, the electrode assembly comprises a first side portion, a second side portion, a third side portion and a fourth side portion. The first side portion and the second side portion are arranged opposite to each other along the length direction of the electrode assembly, and the tab extends from the first side portion. The third side portion and the fourth side portion are arranged opposite to each other along the width direction of the electrode assembly, and the width direction of the electrode assembly, the length direction of the electrode assembly and the thickness direction of the electrode assembly are perpendicular to each other.

[0016] In some embodiments, the conductive member is arranged along the length direction of the electrode assembly around the first region, the first side portion and the second region, and the conductive member further comprises a third conductive layer located at the first side portion and connected to one of the first conductive layer and one of the second conductive layer. The first conductive layer, the second conductive layer and the third conductive layer form a U-shaped structure to bind the first tab, the second tab and the separator in the thickness direction of the electrode assembly. And / or, the conductive member is arranged along the length direction of the electrode assembly around the first region, the second side portion and the second region, and the conductive member further comprises a fourth conductive layer located at the second side portion and connected to one of the first conductive layer and one of the second conductive layer. The first conductive layer, the second conductive layer and the fourth conductive layer form a U-shaped structure to bind the first tab, the second tab and the separator in the thickness direction of the electrode assembly.

[0017] In some embodiments, the length L1 of the first conductive layer satisfies: 0mm < L1≤ 100mm, and the width K1 of the first conductive layer and the width K3 of the electrode assembly satisfy: 0mm≤ K3-K1≤ 100mm. And / or, the length L2 of the second conductive layer satisfies: 0mm < L2≤ 100mm, and the width K2 of the second conductive layer and the width K3 of the electrode assembly satisfy: 0mm≤ K3-K2≤ 100mm. By setting the length of the first conductive layer and / or the length of the second conductive layer within the above range, the conductive member can effectively bind the electrode assembly, effectively electrically connect the first tab and the shell, and also not excessively increase the overall weight of the secondary battery. Preferably, 1mm≤ L1≤ 5mm, 1mm≤ K3-K1≤ 3mm; and / or, 1mm≤ L2≤ 5mm, 1mm≤ K3-K2≤ 3mm.

[0018] In some embodiments, the conductive member is arranged along the width direction of the electrode assembly around the first region, the third side portion and the second region, and the conductive member further comprises a fifth conductive layer located at the third side portion and connected to one of the first conductive layer and one of the second conductive. The first conductive layer, the second conductive layer and the fifth conductive layer form a U-shaped structure to bind the first tab, the second tab and the separators in the thickness direction of the electrode assembly, and / or the conductive member is arranged along the width direction of the electrode assembly around the first region, fourth side portion and second region, and the conductive member further comprises a sixth conductive layer located at the fourth side portion and connected to one of the first conductive layer and one of the second conductive layers. The first conductive layer, the second conductive layer and the sixth conductive layer form a U-shaped structure to bind the first tab, the second tab and the spacer in the thickness direction of the electrode assembly.

[0019] In some embodiments, the length L1 of the first conductive layer and the width K3 of the electrode assembly satisfy: 1mm≤ K3-L1≤ 100mm, and the width K1 of the first conductive layer and the K1≤100mm. And / or, the length L2 of the second conductive layer and the width K3 of the electrode assembly satisfy: 0mm≤K3-L2≤100mm, the width K2 of the second conductive layer and the width K3 of the electrode assembly satisfy: 0mm≤K3-K2≤100mm. K2≤100mm. The above settings can make the first conductive layer and / or the second conductive layer cover the surface of the electrode assembly as much as possible in the width direction, increase the binding and fixing effect on the electrode assembly, and at the same time make the area of the first conductive layer and / or the second conductive layer larger, which is beneficial to enhancing the conductive performance between the shell and the first tab.

[0020] Preferably, 1mm≤K3-L1≤10mm, 1mm≤K3-K2≤10mm. K1≤5mm; and / or, 1mm≤K3-L2≤10mm, 1mm≤K3-K2≤10mm. K2≤5mm.

[0021] In some embodiments, the conductive member includes a conductive agent and a binder; the conductive agent includes at least one of silver powder, copper powder, nickel powder, carbon black, graphene; and the binder includes at least one of epoxy resin, polyurethane, and acrylate. By mixing the conductive agent and the binder to form the conductive member, the conductive member has good adhesion and good conductivity.

[0022] In some embodiments, the thickness H of the conductive member satisfies: 0um<H≤500um. By setting the thickness of the conductive member within the above range, the conductive member can have better conductivity, and can effectively fix the electrode assembly, reduce the space occupied by the accommodation cavity in the shell, and improve the energy density of the secondary battery. In some embodiments, the thickness H of the conductive member satisfies: 5um≤H≤30um. By setting H≥5um, the conductivity of the conductive member can be further improved; by setting H≤30um, the energy density of the secondary battery can be further improved while ensuring that the conductive member has better conductivity.

[0023] In some embodiments, the first tab is an anode tab, and the second tab is a cathode tab. By connecting the anode tab to the shell, the shell corresponds to a hard steel shell, which has higher strength and better wear resistance and impact resistance.

[0024] Another technical solution adopted by the embodiments of the present application is to provide an electronic device including the secondary battery.

[0025] The beneficial effects of the embodiments of the present application are that: the secondary battery of the embodiments of the present application sets the first area on the surface of the first sub-pole piece away from the second sub-pole piece in the first pole piece, and makes the first area contact with the shell to form an electrical connection. Compared with the structure of the prior art using a relay terminal, the structure of the embodiments of the present application can improve the stability of the connection between the first sub-pole piece and the shell, the contact area between the first area and the shell is larger, the impedance is reduced to reduce the energy consumption, in addition, the first pole piece is directly electrically connected with the shell, and does not need to be connected through a relay terminal, the first pole piece can increase the first extension part to increase the space of the first pole piece coated with the active material layer, thereby improving the energy density of the secondary battery. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the specific embodiments of the present application, the drawings needed in the specific embodiment description will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, each element or part is not necessarily drawn according to the actual proportion.

[0027] FIG. 1 is a partial cross-sectional view of a secondary battery of the prior art.

[0028] FIG. 2 is a cross-sectional view of a secondary battery of the embodiments of the present application.

[0029] FIG. 3 is a cross-sectional view of an electrode assembly of the secondary battery of the embodiments of the present application along A-A in FIG. 2.

[0030] FIG. 4 is a cross-sectional view of a first pole piece of an electrode assembly of the secondary battery of the embodiments of the present application along A-A in FIG. 2.

[0031] FIG. 5 is a schematic view of a first current collector of the secondary battery of the embodiments of the present application.

[0032] FIG. 6 is a cross-sectional view of a second pole piece of an electrode assembly of the secondary battery of the embodiments of the present application along A-A in FIG. 2.

[0033] FIG. 7 is a schematic view of a second current collector of the secondary battery of the embodiments of the present application.

[0034] FIG. 8 is a cross-sectional view of the secondary battery of the embodiments of the present application with a conductive piece.

[0035] FIG. 9 is a cross-sectional view of the secondary battery of the embodiments of the present application along B-B in FIG. 8.

[0036] FIG. 10 is a schematic view of an electrode assembly of the secondary battery of the embodiments of the present application around the conductive piece in the length direction.

[0037] FIG. 11 is another schematic view of an electrode assembly of the secondary battery of the embodiments of the present application around the electrically conductive piece in the length direction.

[0038] Fig. 12 is a sectional view of the secondary battery of the embodiment of the application along C-C in Fig. 10.

[0039] Fig. 13 is a schematic view of the electrode assembly of the secondary battery of the embodiment of the application around the conductive member in the width direction.

[0040] Fig. 14 is another schematic view of the electrode assembly of the secondary battery of the embodiment of the application around the conductive member in the width direction.

[0041] Fig. 15 is a sectional view of the secondary battery of the embodiment of the application along D-D in Fig. 13.

[0042] Reference Signs in the Detailed Description of the Invention

[0043] 100, secondary battery;

[0044] 10, case; 11, accommodation chamber;

[0045] 20, electrode assembly; 21, first electrode sheet; 211, first sub-electrode sheet; 212, second sub-electrode sheet; 213, empty foil region; 2131, first region; 2132, second region; 214, first current collector; 2141, first main portion; 2142, first extension portion; 215, first active material layer; 22, second electrode sheet; 221, tab; 222, second current collector; 2221, second main portion; 2222, second extension portion; 223, second active material layer; 23, separator; 24, first side portion; 25, second side portion; 26, third side portion; 27, fourth side portion;

[0046] 30, conductive terminal; X, length direction; Y, width direction; Z, thickness direction;

[0047] 40, conductive member; 41, first conductive layer; 42, second conductive layer; 43, third conductive layer; 44, fourth conductive layer; 45, fifth conductive layer; 46, sixth conductive layer. Embodiments of the Invention

[0048] For the purpose of facilitating the understanding of the present application, the present application will be described in more detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or one or more intervening elements can be present therebetween. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or one or more intervening elements can be present therebetween. The terms "upper", "lower", "inner", "outer", "vertical", "horizontal", and the like as used in the present specification indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are merely used for the purpose of facilitating the description of the present application and simplifying the description, and therefore should not be construed as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the present application. In addition, the terms "first", "second", and the like are merely used for the purpose of description and should not be construed as indicating or implying relative importance.

[0049] Unless otherwise defined, all technical and scientific terms used in the present specification are intended to have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used in the specification of the present application are merely for the purpose of describing specific embodiments and are not intended to limit the present application. The term "and / or" used in the present specification includes any and all combinations of one or more of the associated listed items.

[0050] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as there is no conflict.

[0051] Referring to FIG. 1, in the prior art, a secondary battery 100A includes a case 10A and an electrode assembly 20A, the electrode assembly 20A including a positive electrode tab, a separator, and a negative electrode tab arranged in a stack or wound, the positive electrode tab being provided with a positive electrode tab, the negative electrode tab being provided with a negative electrode tab, a plurality of positive electrode tabs being gathered and welded to a positive electrode adapter terminal 30A, a plurality of negative electrode tabs being gathered and welded to a negative electrode adapter terminal 40A, the positive electrode adapter terminal 30A and the negative electrode adapter terminal 40A extending out of the case 10A to form the positive electrode and the negative electrode of the secondary battery 100A, respectively. The above structure of the secondary battery 100A in the prior art at least has the following problems, first, the welding of the tab to the adapter terminal is prone to cracking at the welding site and breaking of the tab, second, the positive electrode adapter terminal and the negative electrode adapter terminal occupy a relatively large space inside the case, a space 11A needs to be reserved between the electrode assembly 20A and the case 10A to accommodate the positive electrode adapter terminal and the negative electrode adapter terminal, resulting in waste of internal space and low energy density of the secondary battery 100A.

[0052] To solve the above problems, the application provides a secondary battery 100 embodiment, by changing the connection mode of the electrode assembly 20 and the shell 10, specifically, one of the electrode plates in the electrode assembly 20 is extended out of the shell 10 through the conductive terminal 30 to form one electrode of the secondary battery 100, for example, the negative electrode (positive electrode), and the other electrode plate in the electrode assembly 20 is directly electrically connected with the shell 10, so that the shell 10 forms the other electrode of the secondary battery 100, for example, the positive electrode (negative electrode), which reduces the number of conductive terminals 30, releases more space inside the shell 10 to accommodate the electrode plate, improves the energy density of the secondary battery 100, and directly electrically connects the electrode plate with the shell 10, without welding, effectively reducing the risk of poor contact between the electrode plate and the shell 10 caused by the fracture of the electrode plate, thereby improving the stability of the internal structure of the secondary battery 100 and enhancing its anti-falling and anti-impact ability.

[0053] In some embodiments, referring to FIGS. 1-4, the secondary battery 100 includes a shell 10, an electrode assembly 20, and a conductive terminal 30. The shell 10 is provided with a receiving cavity 11, and the electrode assembly 20 is arranged in the receiving cavity 11. The receiving cavity 11 has an electrolyte therein, so that the electrode assembly 20 can perform an electrochemical reaction. The electrode assembly 20 has a length direction X, a width direction Y, and a thickness direction Z perpendicular to each other. The electrode assembly 20 includes a first electrode plate 21, a second electrode plate 22, and a separator 23. The first electrode plate 21 and the second electrode plate 22 are arranged alternately in sequence, and the separator 23 is arranged between adjacent first electrode plates 21 and second electrode plates 22 to insulate the first electrode plates 21 and the second electrode plates 22 and prevent them from directly contacting and short-circuiting. The polarity of the first electrode plate 21 and the polarity of the second electrode plate 22 are opposite, one of which is an anode plate, and the other is a cathode plate.

[0054] The first electrode plate 21 includes a first sub-electrode plate 211, which is located at the outermost side of the electrode assembly 20 in the thickness direction Z of the electrode assembly 20, and the surface of the first sub-electrode plate 211 away from the second sub-electrode plate 212 is provided with a hollow foil area 213. The hollow foil area 213 is electrically connected with the shell 10, for example, the hollow foil area 213 is directly abuttingly connected with the shell 10, or the hollow foil area 213 is indirectly connected with the shell 10 through other structures with conductive properties, so that the first electrode plate 21 is electrically connected with the shell 10, and the shell 10 forms one electrode of the secondary battery 100. It can be understood that the number of the first sub-electrode plate 211 in the first electrode plate 21 can be 1 or 2.

[0055] The conductive terminal 30 is insulatedly arranged in the shell 10, and part of the conductive terminal 30 protrudes out of the shell 10, and part of the conductive terminal 30 is located in the accommodation cavity 11. The second tab 22 includes a tab 221, and the tab 221 is electrically connected with the conductive terminal 30. The conductive terminal 30 constitutes another electrode of the secondary battery 100. In some embodiments, the conductive terminal 30 can be a pole, or a transition piece with a thickness greater than that of the tab, or the tab directly protrudes out of the shell 10, and the tab constitutes the conductive terminal 30, or any two or more combinations of the pole, the transition piece and the tab constitute the conductive terminal 30 in the application.

[0056] Please refer to FIG. 4 and FIG. 5, along the length direction X of the electrode assembly 20, the first tab 21 includes a first main body part 2141 and a first extension part 2142. Along the thickness direction Z of the electrode assembly 20, the projection of the first extension part 2142 does not overlap with the tab 221 and the conductive terminal 30. The length direction X of the electrode assembly 20 is perpendicular to the thickness direction Z of the electrode assembly 20.

[0057] Compared with the structure of adopting two conductive terminals in the prior art, the above structure of the secondary battery 100 in the embodiment of the application can improve the stability of the connection between the first tab 21 and the shell 10, and the contact area between the empty foil area 213 and the shell 10 is larger, which reduces the impedance to reduce the energy consumption. In addition, the first tab 21 is directly electrically connected with the shell 10, and does not need to be connected through a transition terminal, which releases more space in the accommodation cavity 11. The first tab 21 can increase the first extension part 2142 to increase the space of the first tab 21 for coating the active material layer, thereby improving the energy density of the secondary battery 100.

[0058] In some embodiments, the first tab 21 further includes at least one second sub-tab 212, wherein the polarity of the second sub-tab 212 is the same as that of the first sub-tab 211, that is, both are anode tabs or both are cathode tabs. As an example, the first sub-tab 211 and the second sub-tab 212 are independent sub-tabs, which are electrically connected after being stacked in the thickness direction Z of the electrode assembly 20 to jointly constitute the above-mentioned first tab 21. As another example, the first tab 21 is a long strip integrally formed structure, and the first tab 21 is connected and folded to form the first sub-tab 211 and the second sub-tab 212.

[0059] Referring to FIG. 4, when the first tab 21 is a continuously folded structure, the first tab 21 includes a long strip-shaped first current collector 214 and a first active material layer 215 spacedly coated on the first current collector 214, and the first tab 21 is continuously folded at the spacing of the first active material layer 215 to form a first sub-tab 211 and a plurality of second sub-tabs 212. Among them, the first sub-tab 211 and the plurality of second sub-tabs 212 each have a first main body part 2141 and a first extension part 2142, and between the first sub-tab 211 and the plurality of second sub-tabs 212 in the thickness direction Z of the first tab 21, there is a space for the second tab 22 to be stacked.

[0060] In some embodiments, the surface of the first sub-tab 211 away from the second tab 22 is a hollow foil area 213, that is, the surface of the first sub-tab 211 away from the second tab 22 is not coated with an active material layer, so as to increase the contact area of the first tab 21 with the shell 10, increase the transmission path of the current, further reduce the impedance to reduce the energy consumption.

[0061] In some embodiments, the secondary battery 100 includes conductive glue, which is arranged between the hollow foil area 213 and the shell 10, and electrically connects the hollow foil area 213 and the shell 10. The conductive glue helps to fill the small gap between the hollow foil area 213 and the shell 10, so as to enhance the stability and conductivity of the connection between the two.

[0062] In some embodiments, the hollow foil area 213 is provided with a conductive protrusion, which electrically connects the hollow foil area 213 and the shell 10. The forming mode of the conductive protrusion on the first sub-tab 211 includes but is not limited to laser texturing, so that the surface of the current collector of the first sub-tab 211 produces burrs, and the surface roughness of the conductive protrusion area is greater than that of the remaining area; or, by stamping the current collector of the first sub-tab 211 to make it locally protrude. Of course, in other embodiments, the conductive protrusion and the conductive glue can be arranged on the hollow foil area 213 at the same time.

[0063] In some embodiments, referring to FIGS. 3 and 4, the first tab 21 includes two first sub-tabs 211, which are respectively arranged on the two outermost sides of the electrode assembly 20 in the thickness direction Z of the electrode assembly 20. Both of the two outermost sides of the electrode assembly 20 in the thickness direction Z are provided with the first sub-tab 211, and both are electrically connected with the shell 10. On the one hand, it can increase the contact area of the first tab 21 with the shell 10, increase the transmission paths of the current, further reduce the impedance to reduce the energy consumption, on the other hand, it can reduce the insulation requirement between the outer side of the electrode assembly 20 and the shell 10. If the outermost sides of the electrode assembly 20 are the first tab 21 and the second tab 22 respectively, insulation measures need to be added between the second tab 22 and the shell 10.

[0064] It can be understood that the number of the second sub-tab 212 in the first tab 21 can be 0, 1, 2, …, both sides of the second sub-tab 212 are coated with the first active material layer 215, and the first sub-tab 211 is coated with the first active material layer 215 on the surface facing the second sub-tab 212, and the surface away from the second sub-tab 212 can be partially provided with the first active material layer 215 or not provided with the first active material layer 215.

[0065] For the second tab 22 described above, please refer to FIGS. 6 and 7, the second tab 22 includes a tab 221, a second current collector 222, and a second active material layer 223. The second active material layer 223 is coated on both sides of the second current collector 222, and the tab 221 is welded to the second current collector 222, or in other embodiments, the second current collector 222 forms the tab 221 by cutting. In the length direction X of the electrode assembly 20, the second tab 22 includes a second main body part 2221 and a second extension part 2222, and the tab 221 is connected to the second main body part 2221. When the number of the second tab 22 is multiple, the multiple tabs 221 are gathered and electrically connected to the conductive terminal 30.

[0066] Please refer to FIG. 3, in the thickness direction Z of the electrode assembly 20, the first main body part 2141 and the second main body part 2221 are arranged in a stacked manner, and the projection of the first extension part 2142 covers the projection of the second extension part 2222. In the prior art, since the first tab 21 needs to be provided with a relay terminal to be connected to the shell 10, there is space between the electrode assembly 20 and the shell 10 to accommodate the relay terminal. In the present application, the first tab 21 is provided with the empty foil area 213 to be electrically connected to the shell 10, and no space is reserved to accommodate the relay terminal, so that the first tab 21 can be provided with the first extension part 2142 on the basis of the existing structure, and the second tab 22 can be correspondingly provided with the second extension part 2222. The first extension part 2142 and the second extension part 2222 are correspondingly arranged, so that the first active material layer 215 on the first extension part 2142 and the second active material layer 223 on the second extension part 2222 can have an electrochemical reaction, thereby improving the energy density of the secondary battery 100.

[0067] In some embodiments, the first tab 21 is an anode tab, and the second tab 22 is a cathode tab. By connecting the anode tab to the shell 10, the shell 10 corresponds to a hard steel shell, which has higher strength and better wear resistance and impact resistance.

[0068] In some embodiments, referring to FIGS. 8 and 9, the secondary battery 100 includes the conductive member 40 disposed between the first tab 21 and the case 10 to electrically connect the first tab 21 and the case 10. The empty foil region 213 includes a first region 2131 located on a surface of one of the first sub tabs 211 away from the second tab 22 and a second region 2132 located on a surface of the other first sub tab 211 away from the second tab 22, such that the first region 2131 and the second region 2132 are respectively located at two outermost sides in the thickness direction Z of the electrode assembly 20.

[0069] The conductive member 40 includes a first conductive layer 41 disposed between the case 10 and the first region 2131, and the first conductive member 40 bonds the first region 2131 and an inner wall of the case 10 to electrically connect the first region 2131 and the case 10. The first conductive layer 41 helps fill a small gap between the first region 2131 and the case 10 to increase the stability of the connection therebetween and reduce the contact interface impedance of the first region 2131 and the inner wall of the case 10, and the conductive member 40 has good electrical conductivity to enhance the electrical conductivity of the first region 2131 and the case 10.

[0070] In some embodiments, the conductive member 40 further includes a second conductive layer 42 disposed between the case 10 and the second region 2132, and the second conductive member 40 bonds the second region 2132 and an inner wall of the case 10 to electrically connect the second region 2132 and the case 10. The second conductive layer 42 helps fill a small gap between the second region 2132 and the case 10 to increase the stability of the connection therebetween and reduce the contact interface impedance of the second region 2132 and the inner wall of the case 10, and the conductive member 40 has good electrical conductivity to enhance the electrical conductivity of the second region 2132 and the case 10.

[0071] In some embodiments, referring to FIG. 10, the electrode assembly 20 after the lamination of the laminated sheets has a substantially cuboid structure, and the electrode assembly 20 includes a first side 24, a second side 25, a third side 26, and a fourth side 27. The first side 24 and the second side 25 are oppositely disposed in the length direction X of the electrode assembly 20, and the tab 221 extends from the first side 24. The third side 26 and the fourth side 27 are oppositely disposed in the width direction Y of the electrode assembly 20. The conductive member 40 can be wound in the length direction X of the electrode assembly 20 to bundle and fix the electrode assembly 20 in the length direction X, and / or the conductive member 40 can be wound in the width direction Y of the electrode assembly 20 to bundle and fix the electrode assembly 20 in the width direction Y to enhance the structural strength of the electrode assembly 20.

[0072] In some embodiments, referring to FIGS. 10-12, the conductive member 40 is wrapped around the first region 2131, the first side 24, and the second region 2132 in the length direction X of the electrode assembly 20. Specifically, the conductive member 40 further includes a third conductive layer 43 located on the first side 24 and connected to one of the first conductive layer 41 and one of the second conductive layer 42. The first conductive layer 41, the second conductive layer 42, and the third conductive layer 43 form a U-shaped structure to bind the first tab 21, the second tab 22, and the separator 23 in the thickness direction Z of the electrode assembly 20. In some embodiments, the conductive member 40 is wrapped around the first region 2131, the second side 25, and the second region 2132 in the length direction X of the electrode assembly 20, and the conductive member 40 further includes a fourth conductive layer 44 located on the second side 25 and connected to one of the first conductive layer 41 and one of the second conductive layer 42. The

[0073] It is worth mentioning that in the embodiments where the first side 24 of the electrode assembly 20 has the third conductive layer 43 and the second side 25 has the fourth conductive layer 44, the first region 2131 can have one first conductive layer 41 connected to the third conductive layer 43 and the fourth conductive layer 44, or the first region 2131 can have two first conductive layers 41 spaced apart in the length direction X, one of which is connected to the third conductive layer 43 and the other of which is connected to the fourth conductive layer 44. Similarly, the second region 2132 can have one second conductive layer 42 connected to the third conductive layer 43 and the fourth conductive layer 44, or the second region 2132 can have two second conductive layers 42 spaced apart in the length direction X, one of which is connected to the third conductive layer 43 and the other of which is connected to the fourth conductive layer 44. The first conductive layer 41, the second conductive layer 42, the third conductive layer 43, and the fourth conductive layer 44 form a closed loop structure to bind the electrode assembly 20 in the length direction X. Of course, in other embodiments, as shown in FIG. 1, the number of first conductive layers 41 on the first region 2131 can be three or more, and correspondingly, the number of second conductive layers 42 on the second region 2132 and the number of fourth conductive layers 44 correspond to the number of first conductive layers 41.

[0074] In some embodiments, referring to FIGS. 10 and 11, when the conductive member 40 is wound along the length direction X of the electrode assembly 20, the length LI of the first conductive layer 41 satisfies: 0mm < LI ≤ 100mm, and / or the length L2 of the second conductive layer 42 satisfies: 0mm < L2 ≤ 100mm, along the length direction X of the electrode assembly 20. By setting the length LI of the first conductive layer 41 and / or the length L2 of the second conductive layer 42 within the above range, the conductive member 40 can effectively electrically connect the first tab 21 and the housing 10 while effectively binding and fixing the electrode assembly 20 without excessively increasing the overall weight of the secondary battery 100. In some embodiments, the length LI of the first conductive layer 41 satisfies: 1mm ≤ LI ≤ 5mm, and / or the length L2 of the second conductive layer 42 satisfies: 1mm ≤ L2 ≤ 5mm.

[0075] Along the width direction Y of the electrode assembly 20, the width K1 of the first conductive layer 41 and the width K3 of the electrode assembly 20 satisfy: 0mm ≤ K3-K1 ≤ 100mm; and / or the width K2 of the second conductive layer 42 and the width K3 of the electrode assembly 20 satisfy: 0mm ≤ K3-K2 ≤ 100mm. By establishing a relationship between the width K1 of the first conductive layer 41 and / or the width K2 of the second conductive layer 42 and the width K3 of the electrode assembly 20 such that the difference between them is within the range of 0mm to 100mm, the first conductive layer 41 and / or the second conductive layer 42 can cover the surface of the electrode assembly 20 as much as possible in the width direction Y, increasing the binding and fixing effect on the electrode assembly 20, while making the area of the first conductive layer 41 and / or the second conductive layer 42 larger, which is conducive to enhancing the conductive performance between the housing 10 and the first tab 21. In some embodiments, the width K1 of the first conductive layer 41 and the width K3 of the electrode assembly 20 satisfy: 1mm ≤ K3-K1 ≤ 3mm; and the width K2 of the second conductive layer 42 and the width K3 of the electrode assembly 20 satisfy: 1mm ≤ K3-K2 ≤ 3mm.

[0076] In some embodiments, referring to FIGS. 13-15, the conductive member 40 is wrapped around the first region 2131, the third side 26, and the second region 2132 in the width direction Y of the electrode assembly 20. Specifically, the conductive member 40 further includes a fifth conductive layer 45 located on the third side 26 and connected to one of the first conductive layer 41 and one of the second conductive layer 42. The first conductive layer 41, the second conductive layer 42, and the fifth conductive layer 45 form a U-shaped structure to bind the first tab 21, the second tab 22, and the separator 23 in the thickness direction Z of the electrode assembly 20. In some embodiments, the conductive member 40 is wrapped around the first region 2131, the fourth side 27, and the second region 2132 in the width direction Y of the electrode assembly 20, and the conductive member 40 further includes a sixth conductive layer 46 located on the fourth side 27 and connected to one of the first conductive layer 41 and one of the second conductive layer 42. The first conductive layer 41, the second conductive layer 42, and the sixth conductive layer 46 form a U-shaped structure to bind the first tab 21, the second tab 22, and the separator 23 in the thickness direction Z of the electrode assembly 20.

[0077] It is worth noting that in embodiments where the third side 26 of the electrode assembly 20 has the fifth conductive layer 45 and the fourth side 27 has the sixth conductive layer 46, the first region 2131 can have one first conductive layer 41 connected to the fifth conductive layer 45 and the sixth conductive layer 46, or the first region 2131 can have two first conductive layers 41 spaced apart in the width direction Y, one connected to the fifth conductive layer 45 and the other connected to the sixth conductive layer 46. Similarly, the second region 2132 can have one second conductive layer 42 connected to the fifth conductive layer 45 and the sixth conductive layer 46, or the second region 2132 can have two second conductive layers 42 spaced apart in the length direction X, one connected to the fifth conductive layer 45 and the other connected to the sixth conductIVE layer 46. The first conductive layer 41, the second conductive layer 42, the fifth conductive layer 45, and the sixth conductive layer 46 form a closed loop structure to bind the electrode assembly 20 in the width direction Y.

[0078] In some embodiments, referring to FIG. 13 and FIG. 14, when the conductive member 40 is wrapped around the electrode assembly 20 in the width direction Y, along the length direction X of the electrode assembly 20, the length L1 of the first conductive layer 41 and the width K3 of the electrode assembly 20 satisfy: 0mm≤K3-L1≤100mm, and / or, the length L2 of the second conductive layer 42 and the width K3 of the electrode assembly 20 satisfy: 0mm≤K3-L2≤100mm. When the first tab 21 is continuously folded in the length direction X to form a whole, the first tab 21 is continuous at the first side 24 and the second side 25 of the electrode assembly 20, and the electrolyte solution is less likely to enter the inside of the electrode assembly 20 from the first side 24 and the second side 25 to soak the first active material layer 215 and the second active material layer 223. The first tab 21 is discontinuous at the third side 26 and the fourth side 27 of the electrode assembly 20, and the electrolyte solution is more likely to enter the inside of the electrode assembly 20 from the third side 26 and the fourth side 27 to soak the first active material layer 215 and the second active material layer 223. Therefore, the length L1 of the first conductive layer 41 is not too long, the length L1 of the first conductive layer 41 and the width K3 of the electrode assembly 20 are related to each other so that the length L1 of the first conductive layer 41 is smaller than the width K3 of the electrode assembly 20 by about 0mm to 100mm, the length L2 of the second conductive layer 42 and the width K3 of the electrode assembly 20 are related to each other so that the length L2 of the second conductive layer 42 is smaller than the width K3 of the electrode assembly 20 by about 0mm to 100mm, and thus the third side 26 and the fourth side 27 of the electrode assembly 20 are left with enough space for the electrolyte solution to enter the inside of the electrode assembly 20. In some embodiments, the length L1 of the first conductive layer 41 and the width K3 of the electrode assembly 20 satisfy: 1mm≤K3-L1≤10mm, and / or, the length L2 of the second conductive layer 42 and the width K3 of the electrode assembly 2o satisfy: 1mm≤K3-L2≤10mm.

[0079] Along the width direction Y of the electrode assembly 20, the width K1 of the first conductive layer 41 and the width K3 of the electrode assembly 2o satisfy: 0mm≤K3-2 K1≤100mm; and / or, the width K2 of the second conductive layer 42 and the width K3 of the electrode assembly 200 satisfy: 0mm≤K3-2 K2≤100mm. When K3-2 K1 is 0mm, the first conductive layer 41 on the first region 2131 spreads across the width direction Y of the electrode assembly 20, and similarly, when K3-2 When K2 is 0 mm, the second conductive layer 42 on the second region 2132 completely covers the second region 2132 in the width direction Y of the electrode assembly 20. By establishing a relationship between the width K1 of the first conductive layer 41 and / or the width K2 of the second conductive layer 42 and the width K3 of the electrode assembly 20, and satisfying the above-mentioned range requirements, the conductive element 40 can effectively constrain the electrode assembly 20 in the width direction Y, enhancing the structural stability of the electrode assembly 20. In some embodiments, the width K1 of the first conductive layer 41 and the width K3 of the electrode assembly 20 satisfy: 1 ​​mm ≤ K3 - 2 mm. K1≤5mm; and / or, the width K2 of the second conductive layer 42 and the width K3 of the electrode assembly 20 satisfy: 1mm≤K3-2 K2≤5mm.

[0080] In some embodiments, referring to Figures 12 and 15, the thickness H of the conductive element 40 satisfies: 0 μm < H ≤ 500 μm. By setting the thickness of the conductive element 40 within the above range, the conductive element 40 can possess good conductivity while effectively fixing the electrode assembly 20, reducing the space occupied in the receiving cavity 11 inside the housing 10, and improving the energy density of the secondary battery 100. Preferably, the thickness H of the conductive element 40 satisfies: 5 μm ≤ H ≤ 30 μm. Setting H ≥ 5 μm can further improve the conductivity of the conductive element 40; setting H ≤ 30 μm can further improve the energy density of the secondary battery 100 while ensuring that the conductive element 40 has good conductivity.

[0081] In some embodiments, the conductive element 40 may be a conductive coating, such as the conductive adhesive described above, i.e., the conductive element 40 is formed by coating the surface and sides of the electrode assembly 20 with a molten conductive material and then curing it. In other embodiments, the conductive element 40 may also be a conductive tape, i.e., the conductive element 40 is formed by directly attaching a solid film tape with conductive properties to the surface of the electrode assembly 20.

[0082] In some embodiments, the conductive component 40 includes a conductive agent and a binder; the conductive agent includes at least one selected from silver powder, copper powder, nickel powder, carbon black, and graphene; the binder includes at least one selected from epoxy resin, polyurethane, and acrylate. By mixing the conductive agent and the binder to form the conductive component 40, the conductive component 40 possesses both good adhesive properties and good conductive properties.

[0083] This application also provides an embodiment of an electronic device, which includes a secondary battery 100 for storing and releasing electrical energy. The structure and function of the secondary battery 100 can be found in the above embodiments and will not be repeated here.

[0084] Compared with the structure of adopting two adapter terminals in the prior art, the structure of the secondary battery 100 of the embodiment of the present application can improve the stability of the connection of the first sub-pole piece 211 and the shell 10, the contact area of the first region 2131 and the shell 10 is larger, the impedance is reduced to reduce the energy consumption, in addition, the first pole piece 21 is directly electrically connected with the shell 10, and connection through the adapter terminal is not needed, the available space in the accommodation cavity 11 is increased, the first pole piece 21 can increase the first extension part 2142 to increase the space for coating the active material layer of the first pole piece 21, and then the energy density of the secondary battery 100 is improved.

[0085] The above is only an embodiment of the present application, and does not limit the patent scope of the present application, and any equivalent structure or equivalent flow transformation using the content of the specification and the drawings, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A secondary battery, characterized in that, include: The casing has a receiving cavity; An electrode assembly includes a first electrode, a second electrode, and a diaphragm. The first electrode and the second electrode are alternately arranged in sequence. The diaphragm is disposed between adjacent first and second electrodes. The first electrode includes a first sub-electrode. Along the thickness direction of the electrode assembly, the first sub-electrode is located at the outermost edge of the electrode assembly in the thickness direction. The surface of the first sub-electrode away from the second electrode has an empty foil area. The empty foil area is electrically connected to the housing. A conductive terminal is insulated from the housing, with a portion of the conductive terminal extending out of the housing and a portion of the conductive terminal located within the receiving cavity. The second electrode includes a tab, which is electrically connected to the conductive terminal. Along the length direction of the electrode assembly, the first electrode includes a first main body and a first extension. Along the thickness direction of the electrode assembly, the projection of the first extension does not overlap with the tab and the conductive terminal. The length direction of the electrode assembly is perpendicular to the thickness direction of the electrode assembly.

2. The secondary battery according to claim 1, characterized in that, The first electrode also includes at least one second sub-electrode; The first sub-electrode and the second sub-electrode are independent of each other and are electrically connected after being stacked in the thickness direction of the electrode assembly. Alternatively, the first electrode is integrally formed and continuously folded to form the first sub-electrode and the second sub-electrode.

3. The secondary battery according to claim 1 or 2, characterized in that, The surface of the first sub-electrode that is far from the second electrode is the empty foil area.

4. The secondary battery according to any one of claims 1-3, characterized in that, The secondary battery includes a conductive adhesive, which is disposed between the empty foil area and the housing, and the conductive adhesive electrically connects the empty foil area and the housing.

5. The secondary battery according to any one of claims 1-4, characterized in that, The empty foil area is provided with conductive protrusions, which electrically connect the empty foil area and the housing.

6. The secondary battery according to any one of claims 1-5, characterized in that, Along the length of the electrode assembly, the second electrode further includes a second main body and a second extension, and the electrode tab is connected to the second main body; Along the thickness direction of the electrode assembly, the projection of the first extension overlaps the projection of the second extension.

7. The secondary battery according to any one of claims 1-6, characterized in that, The first electrode includes two first sub-electrodes, which are respectively disposed opposite to each other on the two outermost sides of the electrode assembly along the thickness direction of the electrode assembly.

8. The secondary battery according to any one of claims 1-7, characterized in that, The empty foil area includes a first area and a second area. The first area is located on the surface of one of the first sub-electrodes away from the second electrode, and the second area is located on the surface of the other first sub-electrodes away from the second electrode, such that the first area and the second area are located on the two outermost sides of the electrode assembly in the thickness direction. The electrode assembly further includes a conductive element, which includes a first conductive layer and a second conductive layer. The first conductive layer is disposed between the first region and the housing and electrically connects the first region and the housing. The second conductive layer is disposed between the second region and the housing and electrically connects the second region and the housing.

9. The secondary battery according to claim 8, characterized in that, The electrode assembly includes a first side, a second side, a third side, and a fourth side. The first side and the second side are arranged opposite to each other in the length direction of the electrode assembly. The tab extends from the first side. The third side and the fourth side are arranged opposite to each other in the width direction of the electrode assembly. The width direction, the length direction, and the thickness direction of the electrode assembly are all perpendicular to each other.

10. The secondary battery according to claim 9, characterized in that, The conductive element is wound around the first region, the first side and the second region along the length direction of the electrode assembly. The conductive element also includes a third conductive layer, which is located on the first side and is connected to one of the first conductive layers and one of the second conductive layers. And / or, The conductive element is wound around the first region, the second side and the second region along the length direction of the electrode assembly. The conductive element also includes a fourth conductive layer, which is located on the second side and is connected to one of the first conductive layers and one of the second conductive layers.

11. The secondary battery according to any one of claims 8-10, characterized in that, The length L1 of the first conductive layer satisfies: 0mm < L1 ≤ 100mm, and the width K1 of the first conductive layer and the width K3 of the electrode assembly satisfy: 0mm ≤ K3 - K1 ≤ 100mm. And / or, The length L2 of the second conductive layer satisfies: 0mm < L2 ≤ 100mm, and the width K2 of the second conductive layer and the width K3 of the electrode assembly satisfy: 0mm ≤ K3 - K2 ≤ 100mm.

12. The secondary battery according to claim 11, characterized in that, 1mm≤L1≤5mm, 1mm≤K3-K1≤3mm; And / or, 1mm≤L2≤5mm, 1mm≤K3-K2≤3mm.

13. The secondary battery according to claim 9, characterized in that, The conductive element is disposed around the first region, the third side and the second region along the width direction of the electrode assembly. The conductive element further includes a fifth conductive layer, which is located on the third side and is connected to one of the first conductive layers and one of the second conductive layers. And / or, The conductive element is disposed around the first region, the fourth side and the second region along the width direction of the electrode assembly. The conductive element further includes a sixth conductive layer, which is located on the fourth side and is connected to one of the first conductive layers and one of the second conductive layers.

14. The secondary battery according to claim 13, characterized in that, The length L1 of the first conductive layer and the width K3 of the electrode assembly satisfy: 0mm ≤ K3 - L1 ≤ 100mm, and the width K1 of the first conductive layer and the width K3 of the electrode assembly satisfy: 0mm ≤ K3 - 2 K1≤100mm; And / or, The length L2 of the second conductive layer and the width K3 of the electrode assembly satisfy: 0mm ≤ K3 - L2 ≤ 100mm, and the width K2 of the second conductive layer and the width K3 of the electrode assembly satisfy: 0mm ≤ K3 - L2 ≤ 100mm. K2≤100mm.

15. The secondary battery according to claim 14, characterized in that, 1mm≤K3-L1≤10mm,1mm≤K3-2 K1≤5mm; And / or, 1mm≤K3-L2≤10mm,1mm≤K3-2 K2≤5mm.

16. The secondary battery according to any one of claims 8-15, characterized in that, The conductive component includes a conductive agent and a binder; The conductive agent includes at least one of silver powder, copper powder, nickel powder, carbon black, and graphene. The adhesive includes at least one of epoxy resin, polyurethane, and acrylate.

17. The secondary battery according to any one of claims 8-16, characterized in that, The thickness H of the conductive component satisfies: 0um < H ≤ 500um.

18. The secondary battery according to any one of claims 8-17, characterized in that, The thickness H of the conductive component satisfies: 5um ≤ H ≤ 30um.

19. The secondary battery according to any one of claims 1-18, characterized in that, The first electrode is the anode electrode, and the second electrode is the cathode electrode.

20. An electronic device, characterized in that, Includes the secondary battery as described in any one of claims 1-19.

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