Battery and battery preparation method

Abstract

The present application provides a battery and a method for preparing the battery. The battery comprises: a housing including a first accommodating cavity, the first accommodating cavity including a first opening; a cover plate sealing the first opening; and a first winding core assembly, comprising, within the first accommodating cavity: a first laminated winding core including a first winding core body and a first winding core tab connected to the first winding core body; a second laminated winding core including a second winding core body and a second winding core tab connected to the second winding core body; and a connecting piece having one end connected to the first winding core tab and the second winding core tab and the other end connected to the cover plate, wherein the first winding core tab and the second winding core tab are respectively connected to different portions of the connecting piece.

Description

Technical Field

[0001] The present invention relates to the field of batteries, and in particular to a battery and a method for preparing the battery. Background Art

[0002] Range is a limiting factor for consumers choosing new energy vehicles. This concern has been a recurring topic in recent years. Further improving the range of new energy vehicles requires increasing the battery capacity of the vehicle. For battery manufacturers, this means providing products with higher energy density and higher volume density while ensuring safety to meet market demand.

[0003] The mainstream power battery types in the industry are prismatic, pouch, and cylindrical. Prismatic batteries account for 85% of the total installed capacity in the current power battery market, thanks to their module assembly efficiency and cost advantages. Prismatic battery cells can be either wound or laminated.

[0004] Due to its inherent structural characteristics, wound-structured cells cannot fully utilize the internal space of the cell like laminated cells. This disadvantage is particularly prominent in large-sized cells. Therefore, applying laminated-structured wound-structured cells to large-sized cells is an existing design idea to increase the energy density of battery cells.

[0005] Typically, the number of tab layers in a laminated core is twice that of the wound core during production, and the number of tab layers in large-size cells often exceeds 50. In the current production process, when the number of overlapping tab layers between two cores exceeds 100, existing ultrasonic welding technology cannot guarantee the quality of the tabs. Furthermore, when the laminate thickness is large, the length of the tab increases significantly, affecting the yield rate of the core tab segments. Summary of the Invention

[0006] In order to solve the above problems, the present invention discloses a battery and a method for preparing the battery.

[0007] The battery disclosed in the present application includes: a shell, including a first accommodating cavity, the first accommodating cavity including a first opening; a cover plate, closing the first opening; and a first core assembly, in the first accommodating cavity, including: a first laminated core, including a first core body and a first core tab connected to the first core body, a second laminated core, including a second core body and a second core tab connected to the second core body, and a connecting piece, one end of which is connected to the first core tab and the second core tab, and the other end is connected to the cover plate, wherein the first core tab and the second core tab are respectively connected to different parts of the connecting piece.

[0008] In some embodiments, the first core tab and the second core tab are both in sheet shape; and the first core tab and the second core tab are at least partially in contact with each other.

[0009] In some embodiments, the connecting piece includes a first connecting portion, a second connecting portion and a third connecting portion, and the first connecting portion, the second connecting portion and the third connecting portion are connected in sequence, wherein: the first connecting portion is connected to the cover plate; the second connecting portion is connected to the first core electrode; and the third connecting portion is connected to the second core electrode.

[0010] In some embodiments, the second connecting portion includes a second surface; the third connecting portion includes a third surface, the third surface faces the second surface and is spaced apart from the second surface; and the first core tab and the second core tab are located between the second surface and the third surface, the first core tab is connected to the second surface, and the second core tab is connected to the third surface.

[0011] In some embodiments, the connecting piece is in a Z-folded shape.

[0012] In some embodiments, the first connection portion, the second connection portion, and the third connection portion can be flattened to the same plane.

[0013] In some embodiments, when the first connection portion, the second connection portion, and the third connection portion are flattened to the same plane, the connection piece is L-shaped.

[0014] In some embodiments, the connecting piece is connected to the cover plate by laser welding, and the connecting piece is connected to the first winding core tab and the second winding core tab by ultrasonic welding.

[0015] In some embodiments, the first core electrode tab includes a first core positive electrode tab and a first core negative electrode tab, the second core electrode tab includes a second core positive electrode tab and a second core negative electrode tab, and the connecting piece includes a positive electrode connecting piece and a negative electrode connecting piece; the first core positive electrode tab and the second core positive electrode tab are respectively connected to different parts of the positive electrode connecting piece; and the first core negative electrode tab and the second core negative electrode tab are respectively connected to different parts of the negative electrode connecting piece.

[0016] In some embodiments, at least one of the positive electrode connecting plate and the negative electrode connecting plate is provided with a flow hole.

[0017] In some embodiments, the positive electrode connecting sheet is a single-layer aluminum sheet or aluminum alloy sheet, or a composite structure including more than one layer of aluminum sheet or aluminum alloy sheet.

[0018] In some embodiments, the negative electrode connecting sheet is a single-layer copper sheet or copper alloy sheet, or a composite structure including more than one layer of copper sheet or copper alloy sheet.

[0019] In some embodiments, the battery further includes a second winding core assembly, and the structure of the second winding core assembly is symmetrical to that of the first winding core assembly.

[0020] In some embodiments, the connecting piece of the second core assembly and the connecting piece of the first core assembly are respectively connected to different areas of the cover plate.

[0021] The battery preparation method disclosed in the present application includes: providing a first laminate core and a second laminate core, wherein the first laminate core includes a first core body and a first core tab connected to the first core body, and the second laminate core includes a second core body and a second core tab connected to the second core body; providing a connecting piece, the connecting piece includes a first connecting portion, a second connecting portion and a third connecting portion, and the first connecting portion, the second connecting portion and the third connecting portion are connected in sequence; connecting the first core tab and the second core tab to the second connecting portion and the third connecting portion respectively; folding the second connecting portion and the third connecting portion along their connection parts so that the first core tab and the second core tab are fitted together to generate a first core assembly; providing a cover plate; connecting the cover plate to the first connecting portion of the connecting piece; providing a shell, the shell including a first accommodating cavity; placing the first core assembly into the first accommodating cavity; and assembling the cover plate to the shell.

[0022] In some embodiments, the method further includes: generating a second core assembly, the structure of the second core assembly being symmetrical to that of the first core assembly; and connecting the cover plate to a connecting piece of the second core assembly.

[0023] In some embodiments, a connection position between the connecting piece of the first winding core assembly and the cover plate is different from a connection position between the connecting piece of the second winding core assembly and the cover plate.

[0024] In some embodiments, the method further includes: bending the first connecting portion and the second connecting portion along their connecting portions.

[0025] In some embodiments, the connecting piece is connected to the cover plate by laser welding, and the connecting piece is connected to the first winding core tab and the second winding core tab by ultrasonic welding.

[0026] In summary, the present application provides a battery and a method for preparing the battery. The battery and the method for preparing the battery described in the present application are:

[0027] First, by connecting the core tabs of the first laminated core 410 (i.e., the first core tab 412) and the core tabs of the second laminated core 420 (i.e., the second core tab 422) to different locations on the connecting sheet 430 (i.e., the second connecting portion 432 and the third connecting portion 433), the core tabs of the first laminated core 410 and the core tabs of the second laminated core 420 do not need to be stacked for welding, which reduces the difficulty of welding and effectively ensures that the number of ultrasonic welding layers does not exceed the equipment limit.

[0028] Secondly, the first connecting portion 431, the second connecting portion 432, and the third connecting portion 433 are folded in sequence, thereby connecting the tabs of the first and second laminated cores 410, 420 to the electrode 330 and effectively utilizing the space inside the housing 200, thereby improving the energy density of the battery 100.

[0029] Again, the first core tab 412 and the second core tab 422 are arranged in the space formed after the second connecting portion 432 and the third connecting portion 433 are folded: on the one hand, the space is effectively utilized; on the other hand, the second connecting portion 432 and the third connecting portion 433 confine the first core tab 412 and the second core tab 422 in the space, which can protect, support and fix the first core tab 412 and the second core tab 422, and can also prevent the first core tab 412 and the second core tab 422 from loosening. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic diagram of the appearance of a battery provided according to an embodiment of the present application is shown;

[0031] Figure 2 A schematic structural diagram of a housing provided according to an embodiment of the present application is shown;

[0032] Figure 3 A schematic structural diagram of a cover plate and a first winding core assembly according to an embodiment of the present application is shown;

[0033] Figure 4 Shown Figure 3 Detailed view of area A in the middle;

[0034] Figure 5A and Figure 5B 1. A front view and a left view of a first laminated core provided according to an embodiment of the present application are respectively shown;

[0035] Figure 6A and Figure 6B Schematic diagrams of the structure of a flattened negative electrode connecting sheet and a flattened positive electrode connecting sheet provided in accordance with an embodiment of the present application are respectively shown;

[0036] Figure 7A 、 7B 7C respectively show a right side view, a front view, and a top view of a bent negative electrode connecting piece according to an embodiment of the present application;

[0037] Figure 8A 、 8B 8C respectively show a front view, a top view, and a left view of a positive electrode connecting sheet after being bent according to an embodiment of the present application;

[0038] Figure 9A and Figure 9B A three-dimensional view of a bent negative electrode connecting piece and a three-dimensional view of a bent positive electrode connecting piece provided in accordance with an embodiment of the present application are respectively shown;

[0039] Figure 10 A flow chart of a battery preparation method according to an embodiment of the present application is shown;

[0040] Figure 11A and Figure 11B The right side view and the front view respectively show the placement positions of a first laminated core, a second laminated core, and a connecting sheet provided in accordance with an embodiment of the present application;

[0041] Figure 12A and Figure 12B A right side view and a front view are respectively shown after the side surface of a first laminated core and the side surface of a second laminated core are laminated together according to an embodiment of the present application;

[0042] Figure 12C An axonometric view of a first laminate core and a second laminate core after laminating the side thereof according to an embodiment of the present application is shown;

[0043] Figure 12D A schematic structural diagram of a first winding core assembly after the winding core tab is bent according to an embodiment of the present application is shown;

[0044] Figure 13A A schematic structural diagram of a cover plate provided according to an embodiment of the present application is shown;

[0045] Figure 13B and Figure 13C A front view and a bottom view respectively show the placement positions of a cover plate, a first winding core assembly, and a second winding core assembly provided according to an embodiment of the present application; and

[0046] Figure 14 An axonometric view of an assembly after the side of a first core assembly is bonded to the side of a second core assembly according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0047] The following description provides specific application scenarios and requirements of the present invention, with the purpose of enabling those skilled in the art to make and use the contents of the present invention. Various local modifications to the disclosed embodiments will be apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present application. Therefore, the present application is not limited to the embodiments shown, but is intended to be of the widest scope consistent with the claims.

[0048] The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting.

[0049] These and other features of the present application, as well as the operation and function of the related elements of the structure, and the economy of assembly and manufacture of the components, can be significantly improved in view of the following description. Reference is made to the accompanying drawings, all of which form a part of this application. However, it should be clearly understood that the drawings are for illustration and description purposes only and are not intended to limit the scope of this application.

[0050] The following description may significantly improve these and other features of the present application, as well as the operation and function of the related elements of the structure, and the economic efficiency of the assembly and manufacture of the components. All of which are incorporated herein by reference in their entirety into the accompanying drawings, which form a part of this application. However, it should be expressly understood that the drawings are for illustration and description purposes only and are not intended to limit the scope of this application. It should also be understood that the drawings are not drawn to scale.

[0051] Figure 1 The figure shows a schematic diagram of the appearance of a battery 100 provided according to an embodiment of the present application. The battery 100 can be a lithium-ion battery or a hydrogen fuel cell. The battery 100 can be used in various fields, such as a mobile phone battery, a computer battery, a car battery, a drone battery, a ship battery, etc. Specifically, the battery 100 can include a housing 200, a cover plate 300, and a first winding core assembly 400 ( Figure 1 not shown).

[0052] Figure 2 A schematic structural diagram of a housing 200 provided according to an embodiment of the present application is shown.

[0053] refer to Figure 2 The shell 200 may include a accommodating chamber 210. The first core assembly 400 is accommodated in the accommodating chamber 210. The accommodating chamber 210 is used to accommodate the first core assembly 400 and provide effective restraint and protection for the first core assembly 400. The shell 200 may be made of a conductive metal material. For example, aluminum, aluminum alloy, and the like. The shell 200 may be sealed and connected to the cover plate 300 by welding. The shell 200 may also be sealed and connected to the cover plate 300 by other means. The accommodating chamber 210 may include a first opening 211.

[0054] Figure 3 A structural schematic diagram of a cover plate 300 and a first winding core assembly 400 provided according to an embodiment of the present application is shown. Figure 4 Shown Figure 3 Detailed view of area A in the middle.

[0055] refer to Figure 3 and Figure 4 The first core assembly 400 may be disposed in the accommodating chamber 210 . The first core assembly 400 may include a first laminate core 410 , a second laminate core 420 , and a connecting sheet 430 .

[0056] The first laminate core 410 and the second laminate core 420 are connected in series or in parallel to form a first core assembly 400 .

[0057] Figure 5A and Figure 5B 1 and 2 show a front view and a left view of a first laminate core 410 according to an embodiment of the present application. The first laminate core 410 may include a first core body 411 and a first core tab 412 located on the first core body 411 .

[0058] The first core body 411 may include at least one positive electrode sheet, at least one separator and at least one negative electrode sheet. The first core body 411 is formed by stacking the at least one positive electrode sheet, the at least one separator and the at least one negative electrode sheet in sequence. The stacking structure may be a Z-shaped stacking structure, that is, the separator separates adjacent positive and negative electrode sheets in a Z shape, and each stacking structure includes a positive electrode sheet and a negative electrode sheet, and the separator can separate and coat the positive and negative electrode sheets. With the Z-shaped stacking, the internal structure of the first core body 411 is consistent, and the thickness of each part is also consistent accordingly. Therefore, the thickness of the first core body 411 is easier to control. At the same time, the Z-shaped stacking structure makes the internal structure of the first core body 411 consistent, so the positive and negative electrode reaction rates at different positions inside the first core body 411 are relatively consistent, and the first core body 411 is not easy to deform.

[0059] In some embodiments, the first winding core body 411 includes more than 30 consecutive stacked structures including positive electrode sheets, separators, and negative electrode sheets. Optionally, the first winding core body 411 includes at least 50 consecutive stacked structures including positive electrode sheets, separators, and negative electrode sheets.

[0060] The outermost layer of the first winding core body 411 may be wrapped with an insulating film to prevent the first winding core body 411 from directly contacting the housing 200 .

[0061] The first winding core tab 412 is located on the first winding core body 411. In some embodiments, the first winding core tab 412 is located at one end of the first winding core body 411. In some embodiments, the first winding core tab 412 can be located near the edge of the first winding core body 411 facing the surface 406 of the cover plate 300 (e.g., Figure 5B shown).

[0062] refer to Figure 5A The first wound electrode tab 412 may include a first wound negative electrode tab 412 - 1 and a first wound positive electrode tab 412 - 2 .

[0063] The first core positive electrode tab 412-2 includes one or more positive electrode tabs. The first ends of the one or more positive electrode tabs are connected together. After the first ends of the one or more positive electrode tabs are connected together, they are connected to the positive electrode connecting sheet. The connection can be made by welding. Connecting the first ends of the one or more positive electrode tabs together can be used to ensure that the one or more positive electrode tabs will not become loose during the transfer process and can be effectively welded to the positive electrode connecting sheet. The second ends of the one or more positive electrode tabs are respectively connected to the one or more positive electrode sheets in the first core body 411; the connection can be an integrated connection; for example, the aluminum foil partially coated with the positive electrode material is cut using a mold to obtain a sheet that includes both the positive electrode sheet and the positive electrode tab.

[0064] The first winding core negative electrode tab 412-1 includes one or more negative electrode tabs. The first ends of the one or more negative electrode tabs are connected together. After the first ends of the one or more negative electrode tabs are connected together, they are connected to the negative electrode connecting piece. The connection can be made by welding. Connecting the first ends of the one or more negative electrode tabs together can be used to ensure that the one or more negative electrode tabs will not become loose during the transfer process and can be effectively welded to the negative electrode connecting piece. The second ends of the one or more negative electrode tabs are respectively connected to the one or more negative electrode sheets in the first winding core body 411; the connection can be an integrated connection; for example, a copper foil partially coated with a negative electrode material is cut using a mold to obtain a pole piece that includes both a negative electrode sheet and a negative electrode tab.

[0065] Continue to refer Figure 3 and Figure 4 , the structure of the second laminate core 420 is the same as or similar to that of the first laminate core 410. The second laminate core 420 may include a second core body 421 and a second core tab 422 located on the second core body 421. In some embodiments, the second core tab 422 is located at one end of the second core body 421. In some embodiments, the second core tab 422 may be disposed at a position close to the edge of the surface of the second core body 421 facing the cover plate 300. In some embodiments, the position of the second core tab 422 in the second laminate core 420 may be symmetrical to the position of the first core tab 412 in the first laminate core 410 (e.g. Figure 4 shown).

[0066] Continue to refer Figure 3 and Figure 4 The cover plate 300 can be assembled with the housing 200 and close the first opening 211 of the accommodating cavity 210. The closed space formed by assembling the cover plate 300 with the housing 200 can completely enclose the first winding core assembly 400.

[0067] refer to Figure 1 The cover 300 may be provided with a post 330. The post 330 may include a negative post 331 and a positive post 332. The post 330 may be made of a conductive material. The post 330 is the contact point for the battery 100 to electrically connect to an external device and perform charging and discharging.

[0068] refer to Figure 3 and Figure 4 After the cover 300 is assembled with the shell 200, one end of the pole 330 is exposed on the outermost side of the battery 100; the other end of the pole 330 is on the inner side of the battery 100 and is electrically connected to the first winding core tab 412 and the second winding core tab 422 through the connecting piece 430.

[0069] Continue to refer Figure 1 , an injection hole 310 can be provided on the cover plate 300. After the cover plate 300 is assembled to the shell 200, the electrolyte can be injected into the interior of the accommodating cavity 210 through the injection hole 310. The electrolyte can be in liquid state and fill the accommodating cavity 210. The positive electrode sheet, the negative electrode sheet and the diaphragm are immersed in the electrolyte. Taking lithium-ion batteries as an example, the functions of the electrolyte are: on the one hand, the electrolyte can provide some active lithium ions, and the some active lithium ions are used as conductive ions during the charging and discharging process; on the other hand, the electrolyte can provide ion channels, and the ion channels allow lithium ions to move freely inside the shell 200.

[0070] Continue to refer Figure 3 and Figure 4 , an insulating material 320 may be further provided on the cover plate 300. The insulating material 320 may be provided between the cover plate 300 and the first winding core assembly 400. The insulating material 320 may prevent the cover plate 300 and the first winding core assembly 400 from direct contact, thereby improving safety.

[0071] One end of the connecting piece 430 is connected to the first winding tab 412 and the second winding tab 422, and the other end is connected to the cover plate 300. The connecting piece 430 can be made of a conductive material. The connecting piece 430 can ensure electrical connectivity between the pole 330 and the first winding tab 412 and the second winding tab 422.

[0072] According to the battery 100 described in this application, the first core tab 412 and the second core tab 422 are respectively connected to different parts of the connecting sheet 430. In this way, by connecting the core tab of the first laminated core 410 (i.e., the first core tab 412) and the core tab of the second laminated core 420 (i.e., the second core tab 422) to different parts of the connecting sheet 430 (i.e., the second connecting portion 432 and the third connecting portion 433), the core tabs of the first laminated core 410 and the core tabs of the second laminated core 420 do not need to be stacked for welding, which reduces the difficulty of welding and solves the technical problem to be solved by this application.

[0073] Continue to refer Figure 4 In some embodiments, the connecting piece 430 may include a first connecting portion 431, a second connecting portion 432, and a third connecting portion 433. The first connecting portion 431, the second connecting portion 432, and the third connecting portion 433 may be connected in sequence. The first connecting portion 431 may be connected to the cover plate 300; the second connecting portion 432 may be connected to the first winding tab 412; and the third connecting portion 432 may be connected to the second winding tab 422.

[0074] refer to Figure 4 As shown, the first connecting portion 431, the second connecting portion 432, and the third connecting portion 433 of the connecting piece 430 can be in a Z-folded shape. It should be noted that the Z-folded shape is merely used to represent a folded state, and the size of the folded parts (such as the size of the first connecting portion 431, the second connecting portion 432, and the third connecting portion 433) does not constitute a limitation to the present application, nor does the direction of the Z-folding constitute a limitation to the present application.

[0075] The first connecting portion 431 , the second connecting portion 432 and the third connecting portion 433 are folded in sequence, which effectively utilizes the space inside the shell 200 while connecting the core tabs of the first laminated core 410 and the second laminated core 420 to the pole 330 , thereby improving the energy density of the battery 100 .

[0076] Continue to refer Figure 4 The space formed by folding the second connecting portion 432 and the third connecting portion 433 can partially accommodate the first core tab 412 and the second core tab 423. For example, the second connecting portion 432 can include a second surface S, and the third connecting portion 433 can include a third surface T. After the second connecting portion 432 and the third connecting portion 433 are folded along the fold N, the third surface T faces the second surface S and is spaced apart from the second surface S. The first core tab 412 and the second core tab 422 can be located in the space between the second surface S and the second surface T.

[0077] The first core tab 412 and the second core tab 422 are arranged in the space formed after the second connecting portion 432 and the third connecting portion 433 are folded: on the one hand, the space is effectively utilized; on the other hand, the second connecting portion 432 and the third connecting portion 433 confine the first core tab 412 and the second core tab 422 in the space, which can protect, support and fix the first core tab 412 and the second core tab 422, and can also prevent the first core tab 412 and the second core tab 422 from loosening.

[0078] Furthermore, the first core tab 411 is connected to the second surface S, and the second core tab 421 is connected to the third surface T. In this way, the second surface S and the third surface T, which are two opposing surfaces after the second connecting portion 432 and the third connecting portion 433 are folded, ensure that the first core tab 412 and the second core tab 422 are connected to different locations on the connecting sheet 430.

[0079] For the sake of convenience, in the following description of this application, the connection point between the first connection part 431 and the second connection part 432 is represented as the "first bending part M", and the connection point between the second connection part 432 and the third connection part 433 is represented as the "second bending part N".

[0080] Continue to refer Figure 4 , the first connection portion 431, the second connection portion 432 and the third connection portion 433 can be flattened to the same plane. In some embodiments, when the first connection portion 431, the second connection portion 432 and the third connection portion 433 are flattened to the same plane, the connection piece 430 can be L-shaped.

[0081] The connecting tabs 430 may include a negative electrode connecting tab and a positive electrode connecting tab. For the purpose of distinction, in the following description of this application, the negative electrode connecting tab is marked with "10" and the positive electrode connecting tab is marked with "20".

[0082] As an example, Figure 6A and Figure 6B Schematic diagrams of the structure of a flattened negative electrode connecting sheet 10 and a flattened positive electrode connecting sheet 20 provided in an embodiment of the present application are respectively shown.

[0083] refer to Figure 6A, the negative electrode connector 10 is in sheet shape after being flattened. The first connecting portion of the negative electrode connector 10 is 11; the second connecting portion of the negative electrode connector 10 is 12; and the third connecting portion of the negative electrode connector 10 is 13. The connection portion between the first connecting portion 11 and the second connecting portion 12 is the first bending portion M-1, and the connection portion between the second connecting portion 12 and the third connecting portion 13 is the second bending portion N-1. The negative electrode connector 10 is roughly L-shaped after being flattened. Of course, in the unfolded state, the negative electrode connector 10 can also be in other shapes, including, but not limited to, T-shape, straight shape, etc. According to the battery 100 described in the present application, the shape of the negative electrode connector 10 after unfolding can be any shape without deviating from the core spirit of the present application. The first connecting portion 11 and the second connecting portion 12 can be bent along the first bending portion M-1. The bending angle can include any value from 0° to 180°. For example, when the bending angle is 180°, the first connecting portion 11 and the second connecting portion 12 are attached, that is, the first connecting portion 11 and the second connecting portion 12 are folded along the first bending portion M-1 (for example, Figure 4 shown).

[0084] As an example, Figure 7A 、 7B 7C respectively show a right side view, a front view and a top view of a negative electrode connecting sheet 10 provided in an embodiment of the present application after being bent 90° along the bending portion M-1.

[0085] The negative electrode connecting sheet 10 can be a single layer of copper sheet or copper alloy sheet. The negative electrode connecting sheet 10 can also be a composite structure including more than one layer of copper sheet or copper alloy sheet. The thickness of the negative electrode connecting sheet 10 is not greater than 2 mm.

[0086] The negative electrode connecting piece 10 connects the negative electrode post of the end cap 300 with the negative electrode tab of the first laminated core 410 (ie, the first core negative electrode tab 412 - 1 ) and the negative electrode tab of the second laminated core 420 (ie, the second core negative electrode tab 422 - 1 ).

[0087] The negative electrode post of the end cap 300 may be connected to the first connecting portion 11 of the negative electrode connecting tab 10 . For example, ultrasonic welding may be used to weld the first connecting portion 11 of the negative electrode connecting tab 10 and the negative electrode post together.

[0088] The negative electrode tab of the first laminated core 410 and the negative electrode tab of the second laminated core 420 can be connected to the second connecting portion 12 and the third connecting portion 13 of the negative electrode connecting sheet 10, respectively. For example, laser welding can be used to weld the negative electrode tab of the first laminated core 410 to the second connecting portion 12 of the negative electrode connecting sheet 10, and to weld the negative electrode tab of the second laminated core 420 to the third connecting portion 13 of the negative electrode connecting sheet 10.

[0089] In this way, the negative electrode ear of the first laminated core 410 and the negative electrode ear of the second laminated core 420 can be connected to different parts of the connecting sheet respectively by using the second connecting portion 12 and the third connecting portion 13 of the negative electrode connecting sheet 10. The negative electrode ear of the first laminated core 410 and the negative electrode ear of the second laminated core 420 do not need to be stacked and welded, which reduces the difficulty of welding.

[0090] refer to Figure 6B , the positive electrode connector 20 is in a sheet shape after being flattened. The first connecting portion of the positive electrode connector 20 is 21; the second connecting portion of the positive electrode connector 20 is 22; and the third connecting portion of the positive electrode connector 20 is 23. The connection point between the first connecting portion 21 and the second connecting portion 22 is the first bending portion M-2, and the connection point between the second connecting portion 22 and the third connecting portion 23 is the second bending portion N-2. The positive electrode connector 20 is roughly L-shaped after being flattened. Of course, in the unfolded state, the positive electrode connector 20 can also be in other shapes, including, but not limited to, T-shape, straight shape, etc. According to the battery 100 described in the present application, the shape of the positive electrode connector 20 after unfolding can be any shape without deviating from the core spirit of the present application. The first connecting portion 21 and the second connecting portion 22 can be bent along the first bending portion M-2. The bending angle can include any value from 0° to 180°. For example, when the bending angle is 180°, the first connecting portion 21 and the second connecting portion 22 are attached, that is, the first connecting portion 21 and the second connecting portion 22 are folded along the first bending portion M-2.

[0091] Figure 8A 、 8B 8C respectively show a front view, a top view and a left view of a positive electrode connecting sheet 20 provided in an embodiment of the present application after being bent 90° along its bending portion M-2.

[0092] The positive electrode connecting sheet 20 can be a single layer of aluminum sheet or aluminum alloy sheet. The positive electrode connecting sheet 20 can also be a composite structure including more than one layer of aluminum sheet or aluminum alloy sheet. The thickness of the positive electrode connecting sheet 20 is not greater than 2 mm.

[0093] The positive electrode connecting piece 20 connects the positive electrode post of the end cap 300 with the positive electrode tab of the first laminated core 410 and the positive electrode tab of the second laminated core 420 .

[0094] The positive electrode post of the end cap 300 may be connected to the first connecting portion 21 of the positive electrode connecting sheet 20 . For example, ultrasonic welding may be used to weld the first connecting portion 21 of the positive electrode connecting sheet 20 to the positive electrode post.

[0095] The positive electrode tab of the first laminated core 410 (i.e., the first laminated core positive electrode tab 412-2) and the positive electrode tab of the second laminated core 420 (i.e., the second laminated core positive electrode tab 422-2) can be connected to the second connecting portion 22 and the third connecting portion 23 of the positive electrode connecting sheet 20, respectively. For example, laser welding can be used to weld the positive electrode tab of the first laminated core 410 to the second connecting portion 22 of the positive electrode connecting sheet 20, and to weld the positive electrode tab of the second laminated core 420 to the third connecting portion 23 of the positive electrode connecting sheet 20.

[0096] In this way, the second connecting portion 22 and the third connecting portion 23 of the positive electrode connecting sheet 20 can be used to connect the positive electrode ear of the first laminate core 410 and the positive electrode ear of the second laminate core 420 to different parts of the connecting sheet respectively. The positive electrode ear of the first laminate core 410 and the positive electrode ear of the second laminate core 420 do not need to be stacked and welded, which reduces the difficulty of welding.

[0097] In some embodiments, at least one of the positive electrode connecting sheet 20 and the negative electrode connecting sheet 10 is provided with a flow hole. Figure 8A In the embodiment, a flow hole 24 may be provided on the positive electrode connecting sheet 20. The flow hole 24 may be a through hole. The shape of the flow hole 24 may be any shape. As an example, the flow hole 24 may be circular or square. Of course, the flow hole 24 may also be of other shapes. When the charging and discharging current of the battery 100 is too large or short-circuited, the flow hole 24 may protect the battery cell or charging and discharging equipment of the battery 100. For example, when the circuit current is too large, the current flowing through the edge 25 of the flow hole 24 is too large, and the size of the edge 25 is small. When the current exceeds its melting current, the edge 25 will melt and the circuit will be disconnected, that is, the circuit is protected. The flow hole 24 may be provided at any part of the positive electrode connecting sheet 20. For example, the flow hole 24 may be provided on the first connecting portion 21. Of course, in some embodiments, the flow hole may also be provided on the negative electrode connecting sheet 10.

[0098] As an example, Figure 9A and Figure 9B A three-dimensional view of a bent negative electrode connecting tab 10 and a three-dimensional view of a bent positive electrode connecting tab 20 provided in an embodiment of the present application are respectively shown.

[0099] Continue to refer Figure 3 In some embodiments, the battery 100 may further include a second core assembly 500. The structure of the second core assembly 500 is symmetrical to that of the first core assembly 400. For example, the second core assembly 500 may include a laminated core 510, a laminated core 520, and a connecting sheet 530. For the sake of brevity, the structure of the second core assembly 500 will not be further described here.

[0100] In some embodiments, the connecting piece 530 of the second winding core assembly 500 and the connecting piece 430 of the first winding core assembly 400 are respectively connected to different areas on the pole of the cover plate 300. In this way, the connecting piece 430 and the connecting piece 530 do not need to be stacked for welding, which reduces the difficulty of welding.

[0101] This application also provides a battery preparation method. As an example, Figure 10 A flow chart of a battery preparation method 100 provided according to an embodiment of the present application is shown.

[0102] S110 , providing a first laminate core 410 and a second laminate core 420 .

[0103] refer to Figure 5A and Figure 5B The first laminate core 410 may include a first core body 411 and a first core tab 412 connected to the first core body 411. The second laminate core 420 may include a second core body 421 and a second core tab 422 connected to the second core body 421. The structures of the first laminate core 410 and the second laminate core 420 can be referred to the above description and will not be repeated here.

[0104] S130 , providing a connecting piece 430 .

[0105] The connecting piece 430 may include a first connecting portion 431 , a second connecting portion 432 and a third connecting portion 433 , wherein the first connecting portion 431 , the second connecting portion 432 and the third connecting portion 433 are sequentially connected.

[0106] According to the above description, the connecting piece 430 may include a positive connecting piece 20 and a negative connecting piece 10. One positive connecting piece 20 and one negative connecting piece 20 constitute a connecting piece group. One positive connecting piece 20 and one negative connecting piece 10 in a connecting piece group are placed according to a preset rule. For example, referring to Figure 6A and Figure 6B The negative electrode connecting piece 10 and the positive electrode connecting piece 20 are placed symmetrically.

[0107] S150 , bend the first connecting portion 431 and the second connecting portion 432 along the connecting portion M thereof.

[0108] For example, Figure 6A The unfolded negative electrode connecting piece 10 shown in FIG is bent along the first bending portion M-1. Figure 6B The unfolded positive electrode connecting sheet 20 shown in FIG is bent along the first bending portion M-2. Without changing the relative positions of the negative electrode connecting sheet 10 and the positive electrode connecting sheet 20, the axonometric views of the bent negative electrode connecting sheet 10 and the positive electrode connecting sheet 20 are respectively as shown in FIG. Figure 9A and Figure 9B shown.

[0109] S170 , connecting the first winding tab 411 and the second winding tab 421 to the second connecting portion 432 and the third connecting portion 433 respectively.

[0110] As an example, Figure 11A and Figure 11B The right side view and the front view respectively show the placement positions of a first laminate core 410, a second laminate core 420 and a connecting piece 430 provided in accordance with an embodiment of the present application. Figure 11A and Figure 11B Place the first laminate core 410, the second laminate core 420, and the connecting piece 430 as shown. The first laminate core 410 and the second laminate core 420 are symmetrically arranged. The negative electrode tab 412-1 of the first laminate core 410 corresponds to the negative electrode tab 422-1 of the second laminate core 420. The positive electrode tab 412-2 of the first laminate core 410 corresponds to the positive electrode tab 422-2 of the second laminate core 420.

[0111] Connect the core negative electrode tab 412-1 to the second connecting portion 12 of the negative electrode connecting tab 10. Connect the core negative electrode 422-1 to the third connecting portion 13 of the negative electrode connecting tab 10. For example, laser welding can be used to weld the core negative electrode tabs 412-1 and 422-1 to the negative electrode connecting tab 10.

[0112] Connect the core positive electrode tab 412-2 to the second connecting portion 22 of the positive electrode connecting tab 20. Connect the core positive electrode 422-2 to the third connecting portion 23 of the positive electrode connecting tab 20. As an example, laser welding can be used to weld the core positive electrode tabs 412-2 and 422-2 to the positive electrode connecting tab 20.

[0113] In summary: the second connecting portion 12 and the third connecting portion 13 of the negative electrode connecting sheet 10 are used to connect the negative electrode ear 412-1 of the first laminated core 410 and the negative electrode ear 422-1 of the second laminated core 420 together; the second connecting portion 22 and the third connecting portion 23 of the positive electrode connecting sheet 20 are used to connect the positive electrode ear 412-2 of the first laminated core 410 and the positive electrode ear 422-2 of the second laminated core 420 together; the second connecting portion and the third connecting portion on each connecting sheet belong to different parts respectively, so that the core ears of the first laminated core and the core ears of the second laminated core do not need to be stacked for welding, which reduces the difficulty of welding and solves the technical problem to be solved in this application.

[0114] S190 , fold the second connecting portion 432 and the third connecting portion 433 in half along the connecting portion N thereof, so that the first winding core tab 412 and the second winding core tab 422 are attached to each other, thereby forming the first winding core assembly 400 .

[0115] The first laminate core 410 and the second laminate core 420 are respectively Figure 11A The directions P and Q are merged (core closing) so that the side surfaces 601 and 602 of the first laminate core 410 and the second laminate core 420 are in contact with each other.

[0116] As an example, Figure 12A and Figure 12B The right side view and the front view after the side surface 601 and the side surface 602 are bonded together are shown respectively. Figure 12C The isometric view after the side 601 and the side 602 are attached is shown. Figure 12A 、 Figure 12B as well as Figure 12C The first winding core tab and the second winding core tab are in contact with each other and are located in the space between the second connecting portion and the third connecting portion of the connecting piece.

[0117] Will Figure 12C The connecting piece and the winding core tab are taken as a whole, and the winding core tab is bent so that the third connecting portion of the connecting piece is in contact with the surface of the winding core body on which the winding core tab is provided. Figure 12D A schematic structural diagram of the first winding core assembly after the winding core tabs are bent is shown.

[0118] S210 , generating a second winding core assembly 500 .

[0119] The structure of the second winding core assembly 500 is symmetrical to that of the first winding core assembly 400. Similarly, the second winding core assembly 500 can also be manufactured according to the steps shown in the above process. For the sake of brevity, the process of manufacturing the second winding core assembly 500 is not repeated here.

[0120] S230 , providing a cover plate 300 .

[0121] Figure 13A FIG1 shows a schematic diagram of the structure of a cover plate 300 provided according to an embodiment of the present application. The placement position of the cover plate 300 can refer to Figure 13A .

[0122] Place on the cover 300 Figure 12D The first winding core assembly 400 and the second winding core assembly 500 are shown in the state.

[0123] As an example, Figure 13B and Figure 13C The front view and bottom view respectively show the placement positions of a cover plate 300, a first winding core assembly 400, and a second winding core assembly 500 provided according to an embodiment of the present application.

[0124] refer to Figure 13B and Figure 13C Place the first winding core assembly 400 and the second winding core assembly 500 as shown. The first winding core assembly 400 and the second winding core assembly 500 are symmetrically arranged. The first connecting portion 11 of the negative electrode connecting tab 10 in the first winding core assembly 400 corresponds to the first connecting portion 21 of the negative electrode connecting tab 10 in the second winding core assembly 500. The first connecting portion 21 of the positive electrode connecting tab 20 in the first winding core assembly 400 corresponds to the first connecting portion 21 of the positive electrode connecting tab 20 in the second winding core assembly 500.

[0125] S250 , connecting the cover plate 300 to the first connecting portion of the connecting piece of the first winding core assembly.

[0126] S270 , connecting the cover plate 300 to the first connecting portion of the connecting piece of the second winding core assembly.

[0127] The first connecting portion 11 of the negative electrode connecting tab of the first winding core assembly 400 and the first connecting portion 11 of the negative electrode connecting tab of the second winding core assembly 500 are respectively connected to the negative electrode post on the cover plate 300. As an example, the connection method can be laser welding. Figure 13B 4 shows the welding area A between the first connecting portion 11 of the negative electrode connecting piece of the first winding core assembly 400 and the negative electrode post, and the welding area B between the first connecting portion 11 of the negative electrode connecting piece of the second winding core assembly 500 and the negative electrode post.

[0128] Welding region A and welding region B can be independent regions, and welding region A and welding region B do not overlap. That is, the connection position between the negative electrode connecting tab 10 of the first winding core assembly 400 and the cover plate 300 is different from the connection position between the negative electrode connecting tab 10 of the second winding core assembly 500 and the cover plate 300.

[0129] Similarly, the first connecting portion 21 of the positive electrode connecting tab of the first winding core assembly 400 and the first connecting portion 21 of the positive electrode connecting tab of the second winding core assembly 500 are respectively connected to the positive electrode post on the cover plate 300. As an example, the connection method can be laser welding. Figure 13B 4 shows the welding area C between the first connecting portion 21 of the positive electrode connecting sheet of the first winding core assembly 400 and the positive electrode post, and the welding area D between the first connecting portion 21 of the positive electrode connecting sheet of the second winding core assembly 500 and the positive electrode post.

[0130] Welding region C and welding region D can be independent regions, and welding region C and welding region D do not overlap. In other words, the connection position between the positive electrode connecting tab 20 of the first winding core assembly 400 and the cover plate 300 is different from the connection position between the positive electrode connecting tab 20 of the second winding core assembly 500 and the cover plate 300.

[0131] In this way, the first connecting portions of the two sets of connecting plates are used to connect the first winding core assembly 400 and the second winding core assembly 500 to the poles of the cover plate. The first connecting portions of the two sets of connecting plates are connected to the cover plate at different locations, avoiding the need to overlap the connecting plates for welding and reducing the difficulty of welding.

[0132] refer to Figure 13C After welding, the first winding core assembly 400 and the second winding core assembly 500 can be bent along the first bending portion M of the connecting piece. For example, the first winding core assembly 400 and the second winding core assembly 500 can be bent along the first bending portion M of the connecting piece. Figure 13C The directions E and F shown are combined (core closing) to make the side surface 701 of the first winding core assembly 400 and the side surface 702 of the second winding core assembly 500 fit together.

[0133] Figure 14 An axonometric view of an assembly after the side surface 701 of the first winding core assembly 400 is bonded to the side surface 702 of the second winding core assembly 500 according to an embodiment of the present application is shown.

[0134] S290, provide a housing 200.

[0135] The housing 200 includes a first accommodating cavity 210. The structure and function of the housing 200 can be referred to the above description and will not be repeated here.

[0136] S310 , placing the first winding core assembly 400 into the first accommodating cavity 210 .

[0137] Will Figure 14 The first winding core assembly 400 and the second winding core assembly 500 are installed in the first accommodating chamber 210 of the housing 200 , with the side connected to the cover plate 300 facing the first opening of the first accommodating chamber 210 .

[0138] S330 , assembling the cover plate 300 to the housing 200 .

[0139] The cover plate 300 and the housing 200 can be assembled and sealed. After the sealing is completed, the electrolyte can be injected into the first accommodating cavity 210 through the injection hole 310 on the cover plate 300.

[0140] In this way, the battery 100 is prepared.

[0141] In summary, the battery and method for preparing the battery provided in this application are:

[0142] First, by connecting the core tabs of the first laminated core 410 (i.e., the first core tab 412) and the core tabs of the second laminated core 420 (i.e., the second core tab 422) to different locations on the connecting sheet 430 (i.e., the second connecting portion 432 and the third connecting portion 433), the core tabs of the first laminated core 410 and the core tabs of the second laminated core 420 do not need to be stacked for welding, which reduces the difficulty of welding and effectively ensures that the number of ultrasonic welding layers does not exceed the equipment limit.

[0143] Secondly, the first connecting portion 431, the second connecting portion 432, and the third connecting portion 433 are folded in sequence, thereby connecting the tabs of the first and second laminated cores 410, 420 to the electrode 330 and effectively utilizing the space inside the housing 200, thereby improving the energy density of the battery 100.

[0144] Again, the first core tab 412 and the second core tab 422 are arranged in the space formed after the second connecting portion 432 and the third connecting portion 433 are folded: on the one hand, the space is effectively utilized; on the other hand, the second connecting portion 432 and the third connecting portion 433 confine the first core tab 412 and the second core tab 422 in the space, which can protect, support and fix the first core tab 412 and the second core tab 422, and can also prevent the first core tab 412 and the second core tab 422 from loosening.

[0145] In summary, after reading this detailed disclosure, those skilled in the art will appreciate that the foregoing detailed disclosure may be presented by way of example only and may not be limiting. Although not explicitly stated herein, those skilled in the art will understand that this application is intended to encompass various reasonable changes, improvements, and modifications to the embodiments. Such changes, improvements, and modifications are intended to be proposed by this application and are within the spirit and scope of the exemplary embodiments of this application.

[0146] In addition, certain terms in this application have been used to describe embodiments of the present application. For example, "one embodiment," "an embodiment," and / or "some embodiments" mean that a particular feature, structure, or characteristic described in conjunction with that embodiment may be included in at least one embodiment of the present application. Therefore, it is emphasized and should be understood that two or more references to "an embodiment," "one embodiment," or "an alternative embodiment" in various parts of this specification do not necessarily refer to the same embodiment. Furthermore, particular features, structures, or characteristics may be appropriately combined in one or more embodiments of the present application.

[0147] It should be understood that in the foregoing description of the embodiments of the present application, in order to help understand a feature and for the purpose of simplifying the present application, the present application sometimes combines various features in a single embodiment, drawing or its description. Alternatively, the present application disperses various features across multiple embodiments of the present application. However, this does not mean that the combination of these features is necessary. When reading the present application, it is entirely possible for those skilled in the art to extract some of the features and understand them as separate embodiments. In other words, the embodiments in the present application can also be understood as the integration of multiple secondary embodiments. This is also true when the content of each secondary embodiment is less than all the features of a single aforementioned disclosed embodiment.

[0148] In some embodiments, numbers expressing quantities or properties used to describe and claim certain embodiments of the present application should be understood as being modified in some cases by the terms "about," "approximately," or "substantially." For example, unless otherwise indicated, "about," "approximately," or "substantially" can represent a ±20% variation of the value it describes. Therefore, in some embodiments, the numerical parameters listed in the written description and the appended claims are approximate values that can vary depending on the desired properties that a particular embodiment is attempting to obtain. In some embodiments, numerical parameters should be interpreted in light of the number of reported significant digits and by applying ordinary rounding techniques. Although some embodiments of the present application set forth a wide range of numerical ranges and parameters are approximate, the specific examples are listed as precisely as possible.

[0149] Each patent, patent application, patent application publication, and other materials, such as articles, books, specifications, publications, documents, articles, etc., cited herein is hereby incorporated by reference in its entirety for all purposes, except for any prosecution document history related thereto, any equivalent that may be inconsistent or conflicting with this document, or any equivalent prosecution document history that may have a limiting effect on the broadest scope of the claims now or hereafter associated with this document. For example, if there is any inconsistency or conflict between the description, definition, and / or use of terms associated with any incorporated material and the terminology, description, definition, and / or use associated with this document, the terminology in this document shall control.

[0150] Finally, it should be understood that the embodiments of the application disclosed herein are illustrations of the principles of the embodiments of the present application. Other modified embodiments are also within the scope of the present application. Therefore, the embodiments disclosed in the present application are merely examples and not limitations. Those skilled in the art can adopt alternative configurations based on the embodiments in the present application to implement the applications in the present application. Therefore, the embodiments of the present application are not limited to those embodiments that have been precisely described in the application.

Claims

1. A battery, characterized in that: include: The housing comprises a first accommodating cavity, wherein the first accommodating cavity comprises a first opening; a cover plate, closing the first opening; and a first winding core assembly, in the first accommodating cavity, comprising: The first laminate core comprises a first core body and a first core tab connected to the first core body. A second laminate core includes a second core body and a second core tab connected to the second core body, and a connecting piece, one end of which is connected to the first winding core tab and the second winding core tab, and the other end of which is connected to the cover plate, wherein the first winding core tab and the second winding core tab are respectively connected to different parts of the connecting piece; The first core tab and the second core tab are both in sheet shape; and the first core tab and the second core tab are at least partially attached to each other; The connecting piece includes a first connecting portion, a second connecting portion, and a third connecting portion, wherein the first connecting portion, the second connecting portion, and the third connecting portion are connected in sequence, wherein: the first connecting portion is connected to the cover plate; the second connecting portion is connected to the first winding core tab; and the third connecting portion is connected to the second winding core tab; The second connecting portion includes a second surface; the third connecting portion includes a third surface, the third surface facing the second surface and spaced apart from the second surface; and the first core tab and the second core tab are located between the second surface and the third surface, the first core tab is connected to the second surface, and the second core tab is connected to the third surface; The connecting piece is in a Z-folded shape; When the first connection portion, the second connection portion, and the third connection portion are flattened to the same plane, the connection piece is L-shaped.

2. The battery according to claim 1, wherein The connecting piece is connected to the cover plate by laser welding, and the connecting piece is connected to the first winding core tab and the second winding core tab by ultrasonic welding.

3. The battery according to claim 1, wherein The first core electrode tab includes a first core positive electrode tab and a first core negative electrode tab, the second core electrode tab includes a second core positive electrode tab and a second core negative electrode tab, and the connecting piece includes a positive electrode connecting piece and a negative electrode connecting piece; the first core positive electrode tab and the second core positive electrode tab are respectively connected to different parts of the positive electrode connecting piece; and the first core negative electrode tab and the second core negative electrode tab are respectively connected to different parts of the negative electrode connecting piece.

4. The battery according to claim 3, wherein At least one of the positive electrode connecting plate and the negative electrode connecting plate is provided with a flow hole.

5. The battery according to claim 3, wherein The positive electrode connecting sheet is a single-layer aluminum sheet or aluminum alloy sheet, or a composite structure including more than one layer of aluminum sheet or aluminum alloy sheet.

6. The battery according to claim 3, wherein The negative electrode connecting sheet is a single-layer copper sheet or copper alloy sheet, or a composite structure including more than one layer of copper sheets or copper alloy sheets.

7. The battery according to claim 1, wherein It also includes a second winding core assembly, the structure of which is symmetrical to that of the first winding core assembly.

8. The battery according to claim 7, wherein The connecting piece of the second winding core assembly and the connecting piece of the first winding core assembly are respectively connected to different areas of the cover plate.

9. A method for preparing a battery according to any one of claims 1 to 8, characterized in that: include: A first laminated core and a second laminated core are provided, wherein the first laminated core includes a first core body and a first core tab connected to the first core body, and the second laminated core includes a second core body and a second core tab connected to the second core body; a connecting sheet is provided, the connecting sheet includes a first connecting portion, a second connecting portion and a third connecting portion, and the first connecting portion, the second connecting portion and the third connecting portion are connected in sequence; the first core tab and the second core tab are connected to the second connecting portion and the third connecting portion respectively; the second connecting portion and the third connecting portion are folded in half along their connecting portions so that the first core tab and the second core tab are fitted together to generate a first core assembly; further comprising: bending the first connecting portion and the second connecting portion along their connecting portions; providing a cover plate; connecting the cover plate to the first connecting portion of the connecting sheet; providing a shell, the shell including a first accommodating cavity; placing the first core assembly into the first accommodating cavity; and assembling the cover plate to the shell.

10. The method for preparing a battery according to claim 9, wherein: Also includes: generating a second winding core assembly, wherein the structure of the second winding core assembly is symmetrical to that of the first winding core assembly; And the cover plate is connected to the connecting piece of the second winding core assembly.

11. The method for preparing a battery according to claim 10, wherein: A connection position between the connecting piece of the first winding core assembly and the cover plate is different from a connection position between the connecting piece of the second winding core assembly and the cover plate.

12. The method for preparing a battery according to claim 11, wherein: The connecting piece is connected to the cover plate by laser welding, and the connecting piece is connected to the first winding core tab and the second winding core tab by ultrasonic welding.

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