Secondary battery and electric device
By designing the folded part and the empty foil area in the first electrode sheet of the secondary battery, the problems of breakage and space occupation during the formation of the ear beam are solved, and the electrical connection stability and energy density are improved.
Patent Information
- Application Number
- CN202411983286.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-31
- Publication Date
- 2025-03-18
AI Technical Summary
The existing secondary batteries are prone to fracture of the anode ear during the formation of the ear beam, resulting in poor electrical connection between the shell and the anode electrode sheet, and the ear beam occupies the shell space, reducing the energy density.
A secondary battery is designed, and its first electrode sheet includes a first current collector and a first active material layer. The folded portion of the first current collector reduces the space occupied by the pole ear group inside the shell through the alternately connected straight sections and bent sections, and is directly electrically connected to the shell through the empty foil area to increase the contact area.
The stability of the electrical connection between the housing and the first electrode sheet is improved, the space occupied by the electrode group is reduced, and the energy density of the secondary battery is improved.
Smart Images
Figure CN119650974A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of energy storage technology, and in particular to a secondary battery and electrical equipment. Background Art
[0002] In the prior art, a steel case battery includes a housing and an electrode assembly, wherein the electrode assembly includes an anode electrode sheet, a cathode electrode sheet and a diaphragm, wherein the diaphragm separates the anode electrode sheet from the cathode electrode sheet. In order to lead the electrical properties of the anode electrode sheet to the housing, the anode electrode sheet is provided with a plurality of anode tabs, and the plurality of anode tabs need to be gathered to form a tab bundle. Summary of the invention
[0003] For secondary batteries in the prior art, the inventors found that multiple anode tabs need to be bent and then stacked together to form a tab group, and then the tab group is welded to form a tab bundle. In this process, the anode tab is prone to breakage, especially when the number of anode tabs is large, the anode tab is bent more and more easily broken, resulting in poor electrical connection between the shell and the anode pole piece. In addition, the multiple anode tabs are gathered together to form a tab bundle and electrically connected to the shell, which requires a certain space inside the shell, resulting in a loss of energy density of the secondary battery.
[0004] In view of the above situation, it is necessary to provide a secondary battery, which is beneficial to improving the stability of the electrical connection between the shell and the first pole piece and is beneficial to improving the energy density.
[0005] The first aspect of the present application provides a secondary battery, comprising a housing and an electrode assembly, wherein the electrode assembly is contained in the housing. The electrode assembly comprises a first electrode sheet, a second electrode sheet and a diaphragm, wherein the second electrode sheet has an opposite polarity to the first electrode sheet, and the diaphragm separates the first electrode sheet from the second electrode sheet. The first electrode sheet comprises a first current collector and a first active material layer, wherein the first current collector comprises a first section, a folding portion and a second section, wherein the first section and the second section are electrically connected to the folding portion. The first active material layer is disposed on one side of the first section and the second section facing the folding portion, and on two sides of the folding portion oppositely disposed along a first direction, wherein the first direction is parallel to the thickness direction of the electrode assembly. An empty foil area is disposed on one side of the first section facing away from the folding portion, and the empty foil area of the first section is electrically connected to the housing. The folding portion comprises a straight section and a bent section connected alternately. Along the first direction, the second electrode sheet is disposed between the first section and the folding portion, between the second section and the folding portion, and between two adjacent straight sections.
[0006] The folded portion of the first current collector includes straight sections and bent sections that are alternately connected, so that two adjacent straight sections can be electrically connected through the bent sections, which is beneficial to reducing the space occupied by the tab group inside the shell, thereby facilitating improving the energy density of the secondary battery. The first section and the second section are electrically connected to the folded portion, and the first section is electrically connected to the shell, which is beneficial to increasing the contact area between the first pole piece and the shell. Compared with the first pole piece being electrically connected to the shell through the tab group, the empty foil area of the first section is electrically connected to the shell, which enables the first pole piece to be directly electrically connected to the shell, which is beneficial to alleviating the poor electrical connection between the first pole piece and the shell, thereby facilitating improving the stability of the electrical connection between the shell and the first pole piece.
[0007] In one or more of the above embodiments, the first pole piece is an anode pole piece, and the second pole piece is a cathode pole piece.
[0008] In the above embodiment, compared with the case where the first pole piece is a cathode pole piece, the first pole piece is an anode pole piece, which is beneficial to reduce the potential difference between the first pole piece and the shell, thereby helping to reduce the risk of electrochemical corrosion in the electrolyte. In addition, if the first pole piece is a cathode pole piece and is electrically connected to the shell, the requirements for the shell are higher. For example, if the cathode pole piece is made of conventional aluminum material, the shell needs to be an aluminum shell, and the strength of the aluminum shell is relatively low. Under the same strength requirements for the shell, the aluminum shell needs to be thicker. Therefore, compared with the case where the first pole piece is a cathode pole piece, the first pole piece is an anode pole piece, which is beneficial to reduce the loss of energy density of the secondary battery.
[0009] In one or more of the above embodiments, along the first direction, the projection of the straight segment covers the projection of the second pole piece.
[0010] In the above embodiment, the first pole piece can be made to exceed the second pole piece in a direction perpendicular to the first direction, and since the first pole piece is electrically connected to the shell, this helps to reduce the risk of short circuit caused by the second pole piece contacting the shell. In addition, when the first pole piece is an anode pole piece and the second pole piece is a cathode pole piece, it helps to reduce the possibility of lithium deposition.
[0011] In one or more of the above embodiments, a side of the second section facing away from the folded portion is provided with an empty foil area, and the empty foil area of the second section is electrically connected to the housing.
[0012] In the above embodiment, the first section and the second section are both electrically connected to the housing, which can shorten the current path, reduce the internal resistance of the secondary battery, and help improve the charge and discharge rate of the secondary battery.
[0013] In one or more of the above embodiments, the first section is disconnected from the starting section of the folded portion, and the second section is disconnected from the ending section of the folded portion.
[0014] In the above embodiment, when preparing the electrode assembly, it is convenient to set the first active material layer on the side of the first section facing the folding portion, and set the empty foil area on the side of the first section away from the folding portion, which is beneficial to improve the preparation efficiency of the electrode assembly.
[0015] In one or more of the above embodiments, the starting section and the ending section of the folding portion are both straight sections, and along the first direction, the starting section and the ending section of the folding portion are respectively located at two ends of the folding portion. The first section, the second section, and the starting section and the ending section of the folding portion are all provided with a first pole lug, the first pole lug of the first section is directly connected to and electrically connected with the first pole lug of the starting section of the folding portion, and the first pole lug of the second section is directly connected to and electrically connected with the first pole lug of the ending section of the folding portion.
[0016] In the above embodiment, the first pole ear can conveniently establish an electrical connection between the first section and the starting section of the folding portion, and an electrical connection between the second section and the ending section of the folding portion, and the first pole ear can avoid the second pole piece arranged between the first section and the folding portion, and between the second section and the folding portion, which is beneficial to reduce the risk of short circuit.
[0017] In one or more of the above embodiments, the diaphragm includes a first diaphragm, a second diaphragm, a third diaphragm and a fourth diaphragm, the first diaphragm and the second diaphragm are respectively arranged on two opposite sides of the straight section along the first direction, the third diaphragm is arranged between the first section and the second pole piece, and the fourth diaphragm is arranged between the second section and the second pole piece. In the folded portion, the first diaphragm and the second diaphragm are each continuous at the bent section.
[0018] In the above embodiment, in the bending section, the first diaphragm and the second diaphragm can also separate the second pole piece from the first pole piece, which is beneficial to reduce the risk of short circuit caused by contact between the second pole piece and the first pole piece.
[0019] In one or more of the above embodiments, the starting section and the ending section of the folding portion are both bent sections, and along the first direction, the starting section and the ending section of the folding portion are respectively located at two ends of the folding portion. The first section is integrally formed with the starting section of the folding portion, and the second section is integrally formed with the ending section of the folding portion.
[0020] In the above embodiment, the first section and the folding portion, the second section and the folding portion, and the two adjacent straight sections can be electrically connected through the bent section, which is beneficial to further reduce the space occupied by the tab group inside the shell compared to the first section and the second section being electrically connected to the folding portion through the first tab, thereby further improving the energy density of the secondary battery. In addition, compared to the first section and the second section being electrically connected to the folding portion through the first tab, the first section and the starting section of the folding portion are integrally formed, and the second section and the ending section of the folding portion are integrally formed, which is beneficial to further alleviate the poor electrical connection between the first pole piece and the shell, thereby further improving the stability of the electrical connection between the shell and the first pole piece.
[0021] In one or more of the above embodiments, the diaphragm includes a first diaphragm and a second diaphragm, and the first diaphragm and the second diaphragm are respectively arranged on two opposite sides of the folding portion along the first direction. The first diaphragm and the second diaphragm are each continuous at the bending section.
[0022] In the above embodiment, in the bending section, the first diaphragm and the second diaphragm can also separate the second pole piece from the first pole piece, which is beneficial to reduce the risk of short circuit caused by contact between the second pole piece and the first pole piece.
[0023] In one or more of the above embodiments, the secondary battery further comprises a conductive member, which is disposed between the housing and the first section and / or the second section along the first direction. The empty foil area of the first section and / or the empty foil area of the second section is electrically connected to the housing through the conductive member.
[0024] In the above embodiments, the conductive member is used to facilitate the convenience of electrical connection between the first section and / or the second section and the housing.
[0025] In one or more of the above embodiments, the conductive member includes a protrusion, and the protrusion is integrally formed with the housing.
[0026] The above embodiment is helpful to reduce the space required for the conductive member in the housing, thereby helping to reduce the loss of secondary battery energy density caused by the provision of the conductive member.
[0027] In one or more of the above embodiments, the conductive member includes a metal spring sheet, and along the first direction, the metal spring sheet is in a compressed state between the housing and the first section and / or the second section.
[0028] In the above embodiment, the metal spring has a small resistance, which is beneficial to improve the electrical conduction efficiency between the first section and / or the second section and the housing. In addition, the metal spring in a compressed state can abut against the housing and the first section and / or the second section, respectively, which is beneficial to improve the stability of the electrical connection between the first section and / or the second section and the housing.
[0029] In one or more of the above embodiments, the conductive member includes conductive glue, and the empty foil area of the first section and / or the empty foil area of the second section are bonded to the housing through the conductive glue.
[0030] In the above embodiments, the first section and / or the second section are electrically connected and bonded to the outer shell by conductive glue, which can reduce the possibility of movement of the electrode assembly relative to the outer shell, and is beneficial to reducing the risk of deformation of the outer shell due to falling, etc., resulting in failure of the electrical connection between the outer shell and the first section and / or the second section.
[0031] In one or more of the above embodiments, the bending section is not provided with the first active material layer.
[0032] The above embodiment is helpful to reduce the space occupied by the first active material layer, and is helpful to further improve the energy density of the secondary battery.
[0033] The second aspect of the present application provides an electric device, including the secondary battery of the first aspect of the present application. In the secondary battery, the electrical connection between the housing and the first electrode sheet is stable, which is conducive to improving the stability of the electric device during use. The secondary battery has a high energy density, which is conducive to improving the endurance of the electric device. BRIEF DESCRIPTION OF THE DRAWINGS
[0034] Figure 1 A front view of a secondary battery provided in accordance with an embodiment of the present application.
[0035] Figure 2 A top view of a secondary battery provided in accordance with an embodiment of the present application.
[0036] Figure 3 For the first embodiment of this application Figure 1 Cross-section along the midline AA.
[0037] Figure 4 For the first embodiment of this application Figure 2 Cross-section along section line BB.
[0038] Figure 5 The second embodiment of this application is Figure 1 Cross-section along the midline AA.
[0039] Figure 6 The second embodiment of this application is Figure 2 Cross-section along section line BB.
[0040] Figure 7 For an embodiment of the present application Figure 2 Cross-section along the center line CC.
[0041] Figure 8 An overall schematic diagram of an electrical device provided in one embodiment of the present application.
[0042] Main component symbols 1000, electrical equipment; 100, secondary battery; 10, outer shell; 101, receiving cavity; 11, shell; 111, bottom wall; 112, side wall; 12, shell cover; 20, electrode assembly; 21, first pole piece; 211, first current collector; 2111, first section; 2112, folding portion; 2112a, straight section; 2112b, bent section; 2113, second section; 212, first active material layer; 22, second pole piece; 221, second current collector; 222, second active material layer; 23, diaphragm; 231, first diaphragm; 232, second diaphragm; 233, third diaphragm; 234, fourth diaphragm; 30, first pole ear; 40, second pole ear; 50, pole ear bundle; 60, pole column; 70, insulating member; X, first direction; Y, second direction. DETAILED DESCRIPTION
[0043] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.
[0044] It should be noted that when an element is considered to be "connected" to another element, it may be directly connected to the other element or there may be a centrally disposed element at the same time. When an element is considered to be "disposed on" another element, it may be directly disposed on the other element or there may be a centrally disposed element at the same time.
[0045] Unless otherwise specified, the term "plurality" as used herein means two or more than two.
[0046] The terms "first", "second", etc. are only used to distinguish different objects and shall not be understood as indicating or implying relative importance or implying the quantity, specific order or primary and secondary relationship of the indicated technical features.
[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which the present application belongs. The terms used herein in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more related listed items.
[0048] It should be understood that, considering the actual processing tolerance factors, in the technical solution of the present application, when the two elements are arranged parallel / vertically and in the same direction, there may be a certain angle between the two elements, and a tolerance of 0-±10% is allowed between the two elements. A tolerance of 0-±10% is allowed between the two elements greater than, equal to or less than.
[0049] The embodiment of the present application provides a secondary battery, including a shell and an electrode assembly, wherein the electrode assembly is accommodated in the shell. The electrode assembly includes a first electrode sheet, a second electrode sheet and a diaphragm, wherein the second electrode sheet has a polarity opposite to that of the first electrode sheet, and the diaphragm separates the first electrode sheet from the second electrode sheet. The first electrode sheet includes a first current collector and a first active material layer, wherein the first current collector includes a first section, a folding portion and a second section, wherein the first section and the second section are electrically connected to the folding portion. The first active material layer is disposed on one side of the first section and the second section facing the folding portion, and on two sides of the folding portion oppositely disposed along a first direction, wherein the first direction is parallel to the thickness direction of the electrode assembly. An empty foil area is disposed on one side of the first section away from the folding portion, and the empty foil area of the first section is electrically connected to the shell. The folding portion includes a straight section and a bent section connected alternately. Along the first direction, the second electrode sheet is disposed between the first section and the folding portion, between the second section and the folding portion, and between two adjacent straight sections.
[0050] In the secondary battery of the present application, the folded portion of the first current collector includes straight sections and bent sections that are alternately connected, so that two adjacent straight sections can be electrically connected through the bent sections, which is beneficial to reducing the space occupied by the tab group inside the shell, thereby facilitating improving the energy density of the secondary battery. The first section and the second section are electrically connected to the folded portion, and the first section is electrically connected to the shell, which is beneficial to increasing the contact area between the first pole piece and the shell. Compared with the first pole piece being electrically connected to the shell through the tab group, the empty foil area of the first section is electrically connected to the shell, which enables the first pole piece to be directly electrically connected to the shell, which is beneficial to alleviating the poor electrical connection between the first pole piece and the shell, thereby facilitating improving the stability of the electrical connection between the shell and the first pole piece.
[0051] Some embodiments of the present application will be described below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.
[0052] See also Figures 1 to 6 An embodiment of the present application provides a secondary battery 100 , including a housing 10 and an electrode assembly 20 , wherein the electrode assembly 20 is accommodated in the housing 10 .
[0053] In some embodiments, the housing 10 is provided with a receiving cavity 101 , and the electrode assembly 20 is disposed in the receiving cavity 101 .
[0054] In some embodiments, the housing 10 includes a shell 11 and a shell cover 12 . The shell 11 is recessed in a direction away from the shell cover 12 . The shell cover 12 is connected to the shell 11 to form a receiving cavity 101 .
[0055] In some embodiments, the housing 10 is a metal housing, and the material of the housing 10 includes at least one of steel alloy, aluminum alloy and copper alloy. The material of the housing 11 and the housing cover 12 includes at least one of steel alloy, aluminum alloy and copper alloy. In some embodiments, the housing cover 12 is welded to the housing 11.
[0056] In some embodiments, the housing 11 includes a bottom wall 111 and a side wall 112 . The side wall 112 is disposed around the periphery of the bottom wall 111 , and the housing cover 12 covers the side wall 112 .
[0057] See also Figure 3 and Figure 4 The electrode assembly 20 includes a first electrode piece 21 , a second electrode piece 22 and a diaphragm 23 . The second electrode piece 22 has a polarity opposite to that of the first electrode piece 21 . The diaphragm 23 separates the first electrode piece 21 from the second electrode piece 22 .
[0058] In some embodiments, the first electrode sheet 21 includes a first current collector 211 and a first active material layer 212. The first current collector 211 includes a first section 2111, a folded portion 2112, and a second section 2113. The first section 2111 and the second section 2113 are electrically connected to the folded portion 2112. The first active material layer 212 is disposed on one side of the first section 2111 and the second section 2113 facing the folded portion 2112, and on two sides of the folded portion 2112 that are oppositely disposed along a first direction X. The first direction X is parallel to the thickness direction of the electrode assembly 20.
[0059] In some embodiments, the second electrode sheet 22 includes a second current collector 221 and a second active material layer 222 . The second active material layer 222 is disposed on two opposite sides of the second current collector 221 along the first direction X.
[0060] In some embodiments, the first current collector 211 and the second current collector 221 are metal layers. As an illustrative example, the first current collector 211 may be a metal layer including at least one of copper, nickel, tantalum, and titanium, such as a copper foil. The second current collector 221 may be a metal layer including at least one of aluminum, nickel, tantalum, and titanium, such as an aluminum foil.
[0061] In some embodiments, the first active material layer 212 includes a first active material, and the second active material layer 222 includes a second active material. As an illustrative example, the first active material includes at least one of graphite, hard carbon, soft carbon, silicon, silicon-oxygen material, and silicon-carbon material. The second active material includes at least one of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium manganese iron phosphate, or lithium manganese oxide.
[0062] A hollow foil area is provided on one side of the first section 2111 away from the folded portion 2112, and the hollow foil area of the first section 2111 is electrically connected to the housing 10. In some embodiments, the hollow foil area of the first section 2111 is electrically connected to the housing cover 12. The hollow foil area is not provided with the first active material layer 212.
[0063] In some embodiments, the first active material layer 212 may be pre-set on one side of the first section 2111 away from the folded portion 2112, and a hollow foil area is formed by laser cleaning the one side of the first section 2111 away from the folded portion 2112. In this case, a small amount of the first active material may exist in the hollow foil area of the first section 2111 in consideration of the processing error of the actual process.
[0064] In some embodiments, the entire side of the first section 2111 facing away from the folding portion 2112 is provided with an empty foil area, which can make the area of the empty foil area of the first section 2111 larger and help improve the stability of the electrical connection between the empty foil area of the first section 2111 and the shell 10.
[0065] For the convenience of description, the electrical connection between the empty foil area of the first section 2111 and the housing 10 is briefly described as the electrical connection between the first section 2111 and the housing 10 .
[0066] In some embodiments, the secondary battery 100 includes a conductive member (not shown), which is disposed between the housing 10 and the first section 2111 along the first direction X. The first section 2111 is electrically connected to the housing 10 through the conductive member. The conductive member is conducive to improving the convenience of electrical connection between the first section 2111 and the housing 10.
[0067] In some embodiments, the conductive member includes a protrusion, and the protrusion is integrally formed with the housing 10. In this case, it is beneficial to reduce the space required for the conductive member in the housing 10, thereby reducing the loss of energy density of the secondary battery 100 caused by the provision of the conductive member. In some embodiments, a laser roughening process is performed on a side of the housing 10 facing the first section 2111 to form a protrusion on the side of the housing 10 facing the first section 2111.
[0068] In some embodiments, the conductive member includes a metal spring, and the metal spring is in a compressed state between the housing 10 and the first section 2111 along the first direction X. The metal spring has a small resistance, which is beneficial to improving the conductive efficiency between the first section 2111 and the housing 10. In addition, the metal spring in a compressed state can abut against the housing 10 and the first section 2111, respectively, which is beneficial to improving the stability of the electrical connection between the first section 2111 and the housing 10.
[0069] In some embodiments, the conductive member includes a conductive adhesive, and the hollow foil area of the first section 2111 is bonded to the housing 10 via the conductive adhesive. In this case, the first section 2111 is electrically connected and bonded to the housing 10 via the conductive adhesive, which can reduce the possibility of the electrode assembly 20 moving relative to the housing 10, and is conducive to reducing the risk of deformation of the housing 10 due to falling, etc., resulting in failure of the electrical connection between the housing 10 and the first section 2111.
[0070] See also Figure 3 or Figure 5 , the folding portion 2112 includes a straight section 2112a and a bent section 2112b that are alternately connected. In some embodiments, the straight section 2112a and the two adjacent bent sections 2112b connected to the straight section 2112a are roughly in a "Z" shape, wherein the first bent section 2112b connected to the straight section 2112a and the second bent section 2112b are respectively connected to different ends of the straight section 2112a. In some embodiments, the bent section 2112b and the two adjacent straight sections 2112a connected to the bent section 2112b are roughly in a "U" shape, wherein the first straight section 2112a connected to the bent section 2112b and the second straight section 2112a are respectively connected to different ends of the bent section 2112b.
[0071] In some embodiments, the folding portion 2112 includes a starting segment and an ending segment. Along the first direction X, the starting segment and the ending segment of the folding portion 2112 are respectively located at two ends of the folding portion 2112.
[0072] In some embodiments, the starting section and the ending section of the folding portion 2112 are both straight sections 2112a. In some embodiments, the starting section and the ending section of the folding portion 2112 are both bent sections 2112b. In other embodiments, the starting section of the folding portion 2112 is a straight section 2112a, and the ending section of the folding portion 2112 is a bent section 2112b; or, the starting section of the folding portion 2112 is a bent section 2112b, and the ending section of the folding portion 2112 is a straight section 2112a.
[0073] In some embodiments, the first active material layer 212 is disposed on two opposite sides of the straight section 2112 a along the first direction X.
[0074] Along the first direction X, the second electrode sheet 22 is disposed between the first section 2111 and the folded portion 2112, between the second section 2113 and the folded portion 2112, and between two adjacent straight sections 2112a. In some embodiments, along the first direction X, the diaphragm 23 is disposed between the first active material layer 212 and the second electrode sheet 22, and separates the first active material layer 212 and the second electrode sheet 22.
[0075] In some embodiments, along the first direction X, the projection of the straight section 2112a covers the projection of the second pole piece 22. The first pole piece 21 can be made to exceed the second pole piece 22 along the direction perpendicular to the first direction X. Since the first pole piece 21 is electrically connected to the housing 10, this helps to reduce the risk of a short circuit caused by the second pole piece 22 contacting the housing 10. In addition, when the first pole piece 21 is an anode pole piece and the second pole piece 22 is a cathode pole piece, it helps to reduce the possibility of lithium deposition.
[0076] The folded portion 2112 of the first current collector 211 includes straight sections 2112a and bent sections 2112b that are alternately connected, so that two adjacent straight sections 2112a can be electrically connected through the bent sections 2112b, which is beneficial to reducing the space occupied by the tab group inside the housing 10, thereby facilitating improving the energy density of the secondary battery 100. The first section 2111 and the second section 2113 are electrically connected to the folded portion 2112, and the first section 2111 is electrically connected to the housing 10, which is beneficial to increasing the contact area between the first pole piece 21 and the housing 10. Compared with the first pole piece 21 being electrically connected to the housing 10 through the tab group, the first section 2111 is electrically connected to the housing 10 so that the first pole piece 21 is directly electrically connected to the housing 10, which is beneficial to alleviating the poor electrical connection between the first pole piece 21 and the housing 10, thereby facilitating improving the stability of the electrical connection between the housing 10 and the first pole piece 21.
[0077] In some embodiments, the bending section 2112 b is not provided with the first active material layer 212 , which is beneficial to reducing the space occupied by the first active material layer 212 and further improving the energy density of the secondary battery 100 .
[0078] In some embodiments, a side of the second section 2113 facing away from the folding portion 2112 is provided with an empty foil area, and the empty foil area of the second section 2113 is electrically connected to the outer shell 10. The first section 2111 and the second section 2113 are both electrically connected to the outer shell 10, which can shorten the path of the current, reduce the internal resistance of the secondary battery 100, and help improve the charge and discharge rate of the secondary battery 100. In some embodiments, a side of the second section 2113 facing away from the folding portion 2112 is electrically connected to the shell cover 12.
[0079] In some embodiments, the first active material layer 212 may be pre-set on one side of the second section 2113 away from the folded portion 2112, and a hollow foil area may be formed by laser cleaning the side of the second section 2113 away from the folded portion 2112. In this case, a small amount of the first active material may exist in the hollow foil area of the second section 2113 in consideration of the processing error of the actual process.
[0080] In some embodiments, the entire side of the second section 2113 facing away from the folding portion 2112 is provided with an empty foil area, which can make the area of the empty foil area of the second section 2113 larger and help improve the stability of the electrical connection between the empty foil area of the second section 2113 and the shell 10.
[0081] In some embodiments, along the first direction X, the conductive element is disposed between the housing 10 and the second section 2113. The second section 2113 is electrically connected to the housing 10 via the conductive element. The conductive element is advantageous in improving the convenience of the electrical connection between the second section 2113 and the housing 10.
[0082] In some embodiments, a laser roughening process is performed on a surface of the housing 10 facing the second section 2113 to form a protrusion on the surface of the housing 10 facing the second section 2113 .
[0083] In some embodiments, the conductive member includes a metal spring, and the metal spring is in a compressed state between the housing 10 and the second section 2113 along the first direction X. The metal spring has a small resistance, which is beneficial to improving the conductive efficiency between the second section 2113 and the housing 10. In addition, the metal spring in a compressed state can abut against the housing 10 and the second section 2113, respectively, which is beneficial to improving the stability of the electrical connection between the second section 2113 and the housing 10.
[0084] In some embodiments, the conductive member includes a conductive adhesive, and the hollow foil area of the second section 2113 is bonded to the housing 10 via the conductive adhesive. In this case, the second section 2113 is electrically connected and bonded to the housing 10 via the conductive adhesive, which can reduce the possibility of the electrode assembly 20 moving relative to the housing 10, and is conducive to reducing the risk of deformation of the housing 10 due to falling, etc., resulting in failure of the electrical connection between the housing 10 and the second section 2113.
[0085] In some embodiments, please refer to Figure 3 and Figure 4 The first section 2111, the second section 2113 and the folding portion 2112 are separately arranged, and the folding portion 2112 is integrally formed. The straight section 2112a and the bent section 2112b of the folding portion 2112 are formed by reciprocatingly bending the first current collector 211.
[0086] In some embodiments, see Figure 3 , the first section 2111 is disconnected from the starting section of the folding portion 2112, and the second section 2113 is disconnected from the ending section of the folding portion 2112. When preparing the electrode assembly 20, it is convenient to arrange the first active material layer 212 on the side of the first section 2111 facing the folding portion 2112, and to arrange the empty foil area on the side of the first section 2111 facing away from the folding portion 2112, thereby facilitating improving the preparation efficiency of the electrode assembly 20.
[0087] In some embodiments, see Figure 3, the starting section and the ending section of the folding portion 2112 are both straight sections 2112a, the first section 2111, the second section 2113, and the starting section and the ending section of the folding portion 2112 are all provided with a first pole ear 30, the first pole ear 30 of the first section 2111 is directly connected and electrically connected to the first pole ear 30 of the starting section of the folding portion 2112, and the first pole ear 30 of the second section 2113 is directly connected and electrically connected to the first pole ear 30 of the ending section of the folding portion 2112. In this case, the electrical connection between the first section 2111 and the starting section of the folding portion 2112 and the electrical connection between the second section 2113 and the ending section of the folding portion 2112 can be conveniently established through the first pole ear 30, and the first pole ear 30 can avoid the second pole piece 22 arranged between the first section 2111 and the folding portion 2112 and between the second section 2113 and the folding portion 2112, which is conducive to reducing the risk of short circuit.
[0088] In some embodiments, the first electrode tab 30 extends out of the first current collector 211 along a second direction Y. The second direction Y is perpendicular to the first direction X.
[0089] In some embodiments, the first tab 30 of the first section 2111 is welded to the first tab 30 of the starting section of the folded portion 2112, and the first tab 30 of the second section 2113 is welded to the first tab 30 of the ending section of the folded portion 2112. This is beneficial to improve the stability of the connection between the two first tabs 30.
[0090] In some embodiments, please refer to Figure 5 and Figure 6 The first current collector 211 is integrally formed, and the first section 2111, the second section 2113, and the straight section 2112a and the bent section 2112b of the folded portion 2112 are formed by reciprocatingly bending the first current collector 2111.
[0091] In some embodiments, see Figure 5 , the starting section and the ending section of the folding portion 2112 are both bent sections 2112b, the first section 2111 is integrally formed with the starting section of the folding portion 2112, and the second section 2113 is integrally formed with the ending section of the folding portion 2112. In this case, the first section 2111 and the folding portion 2112, the second section 2113 and the folding portion 2112, and two adjacent straight sections 2112a can be electrically connected through the bent section 2112b, compared to the first section 2111 and the second section 2113 being electrically connected through the first electrode ear 30 (see Figure 5) is electrically connected to the folding portion 2112, which is beneficial to further reduce the space occupied by the tab group inside the housing 10, thereby further improving the energy density of the secondary battery 100. In addition, compared with the first section 2111 and the second section 2113 being electrically connected to the folding portion 2112 through the first tab 30, the first section 2111 and the starting section of the folding portion 2112 are integrally formed, and the second section 2113 and the ending section of the folding portion 2112 are integrally formed, which is beneficial to further alleviate the poor electrical connection between the first pole piece 21 and the housing 10, thereby further improving the stability of the electrical connection between the housing 10 and the first pole piece 21.
[0092] In some embodiments, the second pole piece 22 is insulated and connected to the housing 10. Figure 7 The second current collector 221 is provided with a second pole tab 40 , which is connected to the second current collector 221 and extends out of the second current collector 221 along the second direction Y. A plurality of second pole tabs 40 are stacked in sequence along the first direction X and welded to form a pole tab bundle 50 .
[0093] In some embodiments, see Figure 7 The secondary battery 100 includes a pole 60 , which is insulated and fixed to the housing 10 , and the tab bundle 50 is bent in a direction opposite to the first direction X and connected to the pole 60 .
[0094] In some embodiments, the tab bundle 50 is connected to the pole 60 via an adapter (not shown), and the adapter is made of one or more conductive materials such as copper, aluminum, nickel, and nickel alloy.
[0095] In some embodiments, the pole 60 is insulated and fixed to the side wall 112 of the housing 11. Figure 7 The secondary battery 100 includes an insulating member 70 , which is disposed on the side wall 112 of the housing 11 . Along the first direction X and the second direction Y, at least a portion of the insulating member 70 is located between the pole 60 and the side wall 112 .
[0096] In some embodiments, the first pole piece 21 is an anode pole piece, and the second pole piece 22 is a cathode pole piece. Compared with the case where the first pole piece 21 is a cathode pole piece, the first pole piece 21 is an anode pole piece, which is beneficial to reduce the potential difference between the first pole piece 21 and the shell 10, thereby reducing the risk of electrochemical corrosion in the electrolyte. In addition, if the first pole piece 21 is a cathode pole piece and is electrically connected to the shell 10, the requirements for the shell 10 are higher. For example, if the cathode pole piece adopts conventional aluminum material, the shell 10 needs to be an aluminum shell, and the strength of the aluminum shell is low. Under the same strength requirements for the shell 10, the aluminum shell needs a greater thickness, so compared with the case where the first pole piece 21 is a cathode pole piece, the first pole piece 21 is an anode pole piece, which is beneficial to reduce the loss of energy density of the secondary battery 100. In some other embodiments, the first pole piece 21 is a cathode pole piece, and the second pole piece 22 is an anode pole piece.
[0097] In some embodiments, along the first direction X, the projection of the anode electrode piece covers the projection of the cathode electrode piece. This is beneficial to reduce the occurrence of lithium deposition and improve the service life of the secondary battery 100. In addition, when the first electrode piece 21 is an anode electrode piece, the contact area of the first electrode piece 21 that can be electrically connected to the housing 10 is larger, which is beneficial to improve the stability of the electrical connection between the first electrode piece 21 and the housing 10.
[0098] In some embodiments, along the first direction X, the separator 23 is disposed between the first active material layer 212 and the second active material layer 222 , and separates the first active material layer 212 from the second active material layer 222 .
[0099] In some embodiments, the diaphragm 23 is an insulating film material such as a polyethylene film, a polypropylene film, a polyester film, or a polyimide film.
[0100] In some embodiments, see Figure 3 and Figure 4 , the diaphragm 23 includes a first diaphragm 231, a second diaphragm 232, a third diaphragm 233 and a fourth diaphragm 234. The first diaphragm 231 and the second diaphragm 232 are respectively disposed on two opposite sides of the straight section 2112a along the first direction X, the third diaphragm 233 is disposed between the first section 2111 and the second pole piece 22, and the fourth diaphragm 234 is disposed between the second section 2113 and the second pole piece 22. In some embodiments, the third diaphragm 233 is disposed between the first active material layer 212 of the first section 2111 and the second active material layer 222 of the second pole piece 22, and the fourth diaphragm 234 is disposed between the first active material layer 212 of the second section 2113 and the second active material layer 222 of the second pole piece 22.
[0101] In some embodiments, see Figure 3, when the starting section and the ending section of the folding portion 2112 are both straight sections 2112a, the first diaphragm 231 and the second diaphragm 232 are respectively continuous at the bending section 2112b in the folding portion 2112. In this case, at the bending section 2112b, the first diaphragm 231 and the second diaphragm 232 can also separate the second pole piece 22 from the first pole piece 21, which is conducive to reducing the risk of short circuit caused by the second pole piece 22 contacting the first pole piece 21.
[0102] In some embodiments, see Figure 3 When the starting section and the ending section of the folding portion 2112 are both straight sections 2112a, along the first direction X, the diaphragm 23 between the first section 2111 and the folding portion 2112 is discontinuous, and the diaphragm 23 between the folding portion 2112 and the second section 2113 is discontinuous.
[0103] exist Figure 3 In the illustrated embodiment, along the first direction X, the diaphragm 23 located between the first section 2111 and the folding portion 2112 is the first diaphragm 231 and the third diaphragm 233, and the first diaphragm 231 and the third diaphragm 233 are discontinuous (i.e., not connected); the diaphragm 23 located between the first section 2111 and the folding portion 2112 is the first diaphragm 231 and the fourth diaphragm 234, and the first diaphragm 231 and the fourth diaphragm 234 are discontinuous. In some other embodiments, for example, when the number of straight sections 2112a of the folding portion 2112 is an odd number greater than or equal to three, the diaphragm 23 located between the first section 2111 and the folding portion 2112 is a first diaphragm 231 and a third diaphragm 233, and the first diaphragm 231 and the third diaphragm 233 are discontinuous; the diaphragm 23 located between the first section 2111 and the folding portion 2112 is a second diaphragm 232 and a fourth diaphragm 234, and the second diaphragm 232 and the fourth diaphragm 234 are discontinuous.
[0104] In preparation Figure 3In the electrode assembly 20 of the embodiment shown, the first active material layer 212 can be coated at intervals on two opposite sides of the folded portion 2112 in the flat state along the thickness direction, and the first separator 231 and the second separator 232 can be respectively compounded on two opposite sides of the folded portion 2112 along the thickness direction. The first active material layer 212 can be coated only on one side of the first section 2111 along the thickness direction, and the third separator 233 can be compounded on one side of the first section 2111 coated with the first active material layer 212. The first active material layer 212 can be coated only on one side of the second section 2113 along the thickness direction, and the fourth separator 234 can be compounded on one side of the second section 2113 coated with the first active material layer 212. In this way, when the electrode assembly 20 is prepared, not only can the folding portion 2112 in a flat state be bent back and forth to form a straight section 2112a and a bent section 2112b, but the process step of laser cleaning the first section 2111 and the second section 2113 to remove excess first active material layer 212 can also be reduced, which is beneficial to reducing the preparation cost.
[0105] In some embodiments, see Figure 5 and Figure 6 The diaphragm 23 includes a first diaphragm 231 and a second diaphragm 232 , but does not include a third diaphragm 233 and a fourth diaphragm 234 . The first diaphragm 231 and the second diaphragm 232 are respectively disposed on two opposite sides of the folding portion 2112 along the first direction X.
[0106] In some embodiments, see Figure 5 When the starting section and the ending section of the folding portion 2112 are both the bending section 2112b, the first diaphragm 231 and the second diaphragm 232 are respectively continuous at the bending section 2112b in the folding portion 2112. In this case, in the bending section 2112b, the first diaphragm 231 and the second diaphragm 232 can also separate the second pole piece 22 from the first pole piece 21, which is conducive to reducing the risk of short circuit caused by the second pole piece 22 and the first pole piece 21 contacting each other.
[0107] In some embodiments, see Figure 5 When the starting section and the ending section of the folding portion 2112 are both bent sections 2112b, the starting section and the ending section of the folding portion 2112 facing away from the second pole piece 22 are not provided with a diaphragm 23. This can reduce the space occupied by the diaphragm 23, which is beneficial to improving the energy density of the secondary battery 100.
[0108] See also Figure 5 The first section 2111, the folded portion 2112 and the second section 2113 are respectively parts of the first current collector 211 that are connected in sequence. Figure 5In the electrode assembly 20 of the embodiment shown, the first active material layer 212 can be coated at intervals on both sides of the first current collector 211 in the flat state along the thickness direction thereof, and the first separator 231 and the second separator 232 can be respectively compounded on both sides of the first current collector 211 in the thickness direction thereof. In this way, when the electrode assembly 20 is prepared, the first current collector 211 in the flat state can be reciprocally bent to form the first section 2111, the second section 2113, and the straight section 2112a and the bent section 2112b of the folding portion 2112, and then the first section 2111 and the second section 2113 facing away from the folding portion 2112 are laser cleaned to remove the excess first active material layer 212, which is conducive to improving the preparation efficiency.
[0109] In some other embodiments, the side of the bending section 2112 b facing the second pole piece 22 is not provided with the diaphragm 23 .
[0110] In some embodiments, the secondary battery 100 includes an electrolyte (not shown), which is disposed in the receiving cavity 101. The electrolyte facilitates ion conduction between the first active material layer 212 and the second active material layer 222.
[0111] See also Figure 8 One embodiment of the present application provides an electric device 1000, comprising the secondary battery 100 as described above. In the secondary battery 100, the electrical connection between the housing 10 and the first pole piece 21 is stable, which is beneficial to improving the stability of the electric device 1000 during use. The energy density of the secondary battery 100 is high, which is beneficial to improving the endurance of the electric device 1000. The electric device 1000 includes but is not limited to electronic devices such as mobile phones, tablet computers, and laptop computers.
[0112] In addition, those skilled in the art should recognize that the above embodiments are only used to illustrate the present application, and are not intended to limit the present application. As long as they are within the essential scope of the present application, appropriate changes and modifications to the above embodiments are within the scope disclosed in the present application.
Claims
1. A secondary battery, characterized in that: It comprises a housing and an electrode assembly, wherein the electrode assembly is accommodated in the housing; The electrode assembly includes a first electrode sheet, a second electrode sheet and a diaphragm, the second electrode sheet has an opposite polarity to the first electrode sheet, and the diaphragm separates the first electrode sheet from the second electrode sheet; the first electrode sheet includes a first current collector and a first active material layer, the first current collector includes a first section, a folded portion and a second section, the first section and the second section are electrically connected to the folded portion; the first active material layer is arranged on one side of the first section and the second section facing the folded portion, and on two sides of the folded portion that are oppositely arranged along a first direction, and the first direction is parallel to the thickness direction of the electrode assembly; a hollow foil area is arranged on one side of the first section that is away from the folded portion, and the hollow foil area of the first section is electrically connected to the shell; the folded portion includes alternating straight sections and bent sections; along the first direction, the second electrode sheet is arranged between the first section and the folded portion, between the second section and the folded portion, and between two adjacent straight sections.
2. The secondary battery according to claim 1, characterized in that: The first pole piece is an anode pole piece, and the second pole piece is a cathode pole piece.
3. The secondary battery according to claim 2, characterized in that: Along the first direction, the projection of the straight segment covers the projection of the second pole piece.
4. The secondary battery according to claim 1, characterized in that: A hollow foil area is provided on a side of the second section facing away from the folding portion, and the hollow foil area of the second section is electrically connected to the housing.
5. The secondary battery according to claim 4, characterized in that: The first section is disconnected from the starting section of the folded portion, and the second section is disconnected from the ending section of the folded portion.
6. The secondary battery according to claim 5, characterized in that: The starting section and the ending section of the folding portion are both the straight sections, and along the first direction, the starting section and the ending section of the folding portion are respectively located at two ends of the folding portion; the first section, the second section, and the starting section and the ending section of the folding portion are all provided with a first pole ear, the first pole ear of the first section is directly connected to the first pole ear of the starting section of the folding portion and is electrically conductive, and the first pole ear of the second section is directly connected to the first pole ear of the ending section of the folding portion and is electrically conductive.
7. The secondary battery according to claim 6, characterized in that: The diaphragm includes a first diaphragm, a second diaphragm, a third diaphragm and a fourth diaphragm, the first diaphragm and the second diaphragm are respectively arranged on two surfaces of the straight section that are opposite to each other along the first direction, the third diaphragm is arranged between the first section and the second pole piece, and the fourth diaphragm is arranged between the second section and the second pole piece; in the folding portion, the first diaphragm and the second diaphragm are each continuous at the bending section.
8. The secondary battery according to claim 1 or 4, characterized in that: The starting section and the ending section of the folding portion are both the bending sections. Along the first direction, the starting section and the ending section of the folding portion are respectively located at two ends of the folding portion; the first section is integrally formed with the starting section of the folding portion, and the second section is integrally formed with the ending section of the folding portion.
9. The secondary battery according to claim 8, characterized in that: The diaphragm includes a first diaphragm and a second diaphragm, wherein the first diaphragm and the second diaphragm are respectively arranged on two opposite sides of the folding portion along the first direction; the first diaphragm and the second diaphragm are respectively continuous at the bending section.
10. The secondary battery according to claim 4, characterized in that: The secondary battery further comprises a conductive member, which is arranged between the housing and the first section and / or the second section along the first direction; the empty foil area of the first section and / or the empty foil area of the second section is electrically connected to the housing through the conductive member.
11. The secondary battery according to claim 10, characterized in that: The conductive member includes a protrusion, and the protrusion is integrally formed with the housing.
12. The secondary battery according to claim 11, characterized in that: The conductive member includes a metal spring sheet, and along the first direction, the metal spring sheet is in a compressed state between the housing and the first section and / or the second section.
13. The secondary battery according to claim 11, characterized in that: The conductive member includes conductive adhesive, and the empty foil area of the first section and / or the empty foil area of the second section are bonded to the housing through the conductive adhesive.
14. The secondary battery according to claim 1, characterized in that: The bending section is not provided with the first active material layer.
15. An electrical equipment, characterized in that: The invention comprises the secondary battery according to any one of claims 1 to 14.