High-capacity battery and preparation method thereof

Abstract

The invention provides a high-capacity battery and a preparation method thereof. The high-capacity battery comprises a shell, a cover plate assembly, a first connecting sheet, a second connecting sheet and a battery module, the battery module comprises at least two stacked cores which are sequentially stacked in the inner cavity of the shell; each laminated core is provided with a first switching assembly and a second switching assembly, the first switching assemblies of two adjacent laminated cores are connected in parallel through a first connecting piece, and the second switching assemblies of two adjacent laminated cores are connected in parallel through a second connecting piece; the first connecting piece and the second connecting piece independently comprise a connecting body, the connecting body is provided with a first surface and a second surface which are opposite, and the two ends of the connecting body are bent towards one side of the second surface to form a first bent part and a second bent part. And the first bending part and the second bending part are respectively connected with the first switching components or the second switching components of the two adjacent laminated cores. The problem of battery polarization is relieved, the battery manufacturing method is simplified, and the battery capacity is greatly increased.

Description

Technical Field

[0001] The invention belongs to the field of batteries and relates to a high-capacity battery and a preparation method thereof. Background Art

[0002] Large-capacity single cells can significantly increase the energy density of energy storage systems and are one of the important trends in the future development of energy storage systems. Using large-capacity single cells can simplify the integrated assembly process, reduce the number of parallel connections, reduce the difficulty of BMS, and significantly save the investment in land infrastructure, containers, etc., thereby further reducing production costs.

[0003] However, the increase in battery capacity has led to larger and larger sizes of single cells, and the difficulty of manufacturing has increased accordingly. Traditional batteries have two tab structures. With the development requirements, batteries with higher energy density are needed. Single cells gradually adopt stacking methods, and the corresponding full-tab design and multi-level tab design have become the main development directions. The assembly and welding process of the full-tab solution is simpler, but because the positive and negative tabs are at both ends of the battery cell, two cover plates are usually required, the welding process is complicated, and the PACK assembly process is cumbersome. The existing side-outlet structure solution often uses an L-shaped current collector, but there is a problem that the residual heat from the welding of the main body and the tab can easily burn the core package, resulting in a short circuit between the positive and negative electrodes, causing an internal short circuit in the battery, and in severe cases, it may cause the battery to catch fire. In addition, the battery with the side-outlet structure is severely polarized, which makes the battery front cycle climb data poor.

[0004] Therefore, it is very important to provide a battery structure with convenient processing, reasonable tab design, and excellent overall electrical performance. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention aims to provide a high-capacity battery and a method for preparing the same, which alleviates the battery polarization problem, simplifies the battery manufacturing method, and greatly increases the battery capacity.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In the first aspect, the present invention provides a high-capacity battery, which includes a shell, a cover plate assembly, a first connecting piece, a second connecting piece and a battery module; the battery module includes at least two stacked cores, and at least two of the stacked cores are stacked in sequence in the inner cavity of the shell; an opening is opened at the top of the shell, and the cover plate assembly is arranged at the opening; the stacked core is provided with a first adapter assembly and a second adapter assembly, the first adapter assemblies of two adjacent stacked cores are connected in parallel through the first connecting piece, and the second adapter assemblies of two adjacent stacked cores are connected in parallel through the second connecting piece; the first connecting piece and the second connecting piece independently include a connecting body, the connecting body has a first surface and a second surface opposite to each other, the first surface is connected to the cover plate assembly, and the second surface is close to the stacked core; the two ends of the connecting body are bent toward one side of the second surface to form a first bending portion and a second bending portion, the first bending portion and the second bending portion of the first connecting piece are respectively connected to the first adapter assemblies of the two adjacent stacked cores, and the first bending portion and the second bending portion of the second connecting piece are respectively connected to the second adapter assemblies of the two adjacent stacked cores.

[0008] The high-capacity battery of the present invention adopts a flexible and foldable connecting sheet design to connect the positive or negative electrodes of the laminated battery cell structure in parallel. The connecting sheet can be transformed into different bending states according to different needs to meet assembly production requirements. It is also beneficial to reduce the transfer height, reduce the battery cell cost, optimize the battery weight, improve the utilization rate of the internal space of the shell, and has a high flow capacity, which effectively improves the battery capacity.

[0009] As a preferred technical solution of the present invention, the first bending portion and the second bending portion independently have a first side surface and a second side surface relative to each other; the first side surface of the first bending portion is attached to the connecting body, and the second side surface of the first bending portion is connected to the first adapter component or the second adapter component; the first side surface of the second bending portion is attached to the connecting body, and the second side surface of the second bending portion is connected to the first adapter component or the second adapter component.

[0010] It should be noted that the first bending portion and the second bending portion in the present invention are both bent from the plane where the connecting body is located to one side of its second surface, and the first bending portion and the second bending portion are arranged opposite to each other. Technical personnel in this field can adjust the bending angle according to actual conditions.

[0011] As a preferred technical solution of the present invention, the stacked core includes a first battery cell group and a second battery cell group which are stacked in sequence, and a first positive pole ear and a first negative pole ear which are gathered along a first direction are arranged at one end of the first battery cell group close to the cover plate assembly, and a second positive pole ear and a second negative pole ear which are gathered along a second direction are arranged at one end of the second battery cell group close to the cover plate assembly, and the first direction is opposite to the second direction; the first positive pole ear is in a "U" shape, and the second positive pole ear is in an "S" shape, and is independently connected to the first connecting piece to form the first adapter assembly; the first negative pole ear is in a "U" shape, and the second negative pole ear is in an "S" shape, and is independently connected to the second connecting piece to form the second adapter assembly.

[0012] It should be noted that the first battery cell group and the second battery cell group in the present invention are respectively formed by stacking a plurality of battery cell monomers in sequence, and the positive electrode tabs and negative electrode tabs of the battery cell monomers are both laminated structures and are led out from one side of the battery cell monomers. A plurality of laminated positive electrode tabs are gathered along the first direction or the second direction to form a positive electrode tab portion, and a plurality of laminated negative electrode tabs are gathered along the first direction or the second direction to form a negative electrode tab portion.

[0013] The battery module of the present invention is a battery structure with at least four cores, and adopts a top-out multi-electrode tab stacking form, which alleviates the battery polarization problem and facilitates the turnover of the battery core. The tabs of the first battery core group and the second battery core group are folded in opposite directions, so that the first positive pole tab and the second positive pole tab in the initial state after folding are designed to be spaced back to back, and the first negative pole tab and the second negative pole tab in the initial state after folding are designed to be spaced back to back, which optimizes the tab height, so that the height of the tabs in the battery module is consistent and the structure is compact. The initial state of each tab after folding is a multi-layer stacking structure. After being connected to the first connecting piece or the second connecting piece, the tabs folded in the first direction are bent in a "U" shape, and the tabs folded in the second direction are bent in an "S" shape. Compared with the traditional battery structure, the present invention reduces the tab height, improves the space utilization rate in the shell, reduces material consumption, and saves manufacturing costs.

[0014] As a preferred technical solution of the present invention, the cover plate assembly includes a top cover body, on which a first battery cell pole and a second battery cell pole are arranged, the first battery cell pole is partially located in the shell and connected to the first connecting piece, and the second battery cell pole is partially located in the shell and connected to the second connecting piece.

[0015] An insulating layer is arranged around the surface of the top cover body close to the inner cavity of the shell, and the insulating layer extends toward the inner cavity of the shell; a gap is left between the insulating layer and the outer edge of the connecting body.

[0016] The insulating layer in the present invention is used to insulate the upper cover assembly from the battery cell in the shell to avoid the problem of battery short circuit.

[0017] It should be noted that the outer edge of the connection body in the present invention refers to the fold line edge formed by bending the two ends of the connection body.

[0018] As a preferred technical solution of the present invention, the height of the first cell pole and the second cell pole in the shell is greater than the height of the insulating layer. The second surface of the connecting body is provided with a receiving convex bump, and the receiving convex bump protrudes toward the inner cavity of the shell. The end of the first cell pole extending out of the insulating layer is located in the receiving convex bump of the first connecting piece; the end of the second cell pole extending out of the insulating layer is located in the receiving convex bump of the second connecting piece.

[0019] The connecting piece of the present invention has a concave-convex structure, and the first surface of the connecting body is concave toward the inner cavity of the shell to form a hollow accommodating convex bump, which plays a positioning role in the preparation process and reserves more available space for the inner cavity of the shell.

[0020] In the first direction or the second direction, the linear distance between the insulating layer and the outer edge of the connecting body is 1 to 2 mm, for example, it can be 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm or 2 mm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0021] The insulating layer is also provided with an escape opening.

[0022] After the cover plate assembly is connected and fixed to the first connecting piece and the second connecting piece respectively, a pressure mechanism commonly used by those skilled in the art is used to bend the first connecting piece and the second connecting piece through the avoidance opening.

[0023] As a preferred technical solution of the present invention, two thinning grooves are provided on the surface of the connecting body, and the first bending portion and the second bending portion are formed by bending along the two thinning grooves.

[0024] The first connecting piece and the second connecting piece of the present invention are flat plate structures, which are convenient for material transportation and loading operations. During the subsequent preparation process, they are bent along the reserved thinning grooves, thereby improving the bending yield.

[0025] The width of the thinning groove is 3 to 4 mm, for example, it can be 3 mm, 3.1 mm, 3.2 mm, 3.3 mm, 3.4 mm, 3.5 mm, 3.6 mm, 3.7 mm, 3.8 mm, 3.9 mm or 4 mm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0026] The depth of the thinning groove is 0.2-0.5 mm, for example, it can be 0.2 mm, 0.22 mm, 0.25 mm, 0.26 mm, 0.28 mm, 0.3 mm, 0.35 mm, 0.38 mm, 0.4 mm, 0.44 mm, 0.45 mm, 0.48 mm or 0.5 mm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0027] Two arc-shaped openings arranged opposite to each other are formed on both sides of the connecting body.

[0028] An anti-stuck corner is arranged along the outer edge of the accommodating convex bump.

[0029] In the present invention, arc-shaped openings are arranged on both non-bent sides of the connecting body to avoid interference with the battery filling port.

[0030] As a preferred technical solution of the present invention, a supporting plate is further provided at the bottom of the inner cavity of the shell.

[0031] The inner cavity side wall of the shell is also provided with a protective layer, and the protective layer is arranged around the periphery of the battery module. The two ends of the protective layer are also connected to the insulating layer and the supporting plate respectively.

[0032] The present invention uses an insulating layer, a protective layer and a supporting plate to cover and insulate the battery module, thereby preventing the battery core from directly contacting the shell and causing a battery short circuit.

[0033] In a second aspect, the present invention provides a method for preparing the high-capacity battery according to the first aspect, the method comprising:

[0034] The first adapter components of two adjacent stacked cores are connected in parallel by using a first connecting sheet;

[0035] The second adapter components of two adjacent stacked cores are connected in parallel by using a second connecting piece;

[0036] The first connecting piece and the second connecting piece are independently connected to the cap plate assembly and then installed into a shell to obtain a high-capacity battery.

[0037] As a preferred technical solution of the present invention, the preparation method comprises the following steps:

[0038] (1) bending the first bending portion and the second bending portion of the first connecting piece and the second connecting piece respectively, so that the first bending portion and the second bending portion are independently perpendicular to the plane where the connecting body is located;

[0039] (2) the first positive electrode ear and the first negative electrode ear of the first battery cell group are gathered in a first direction, and the second positive electrode ear and the second negative electrode ear of the second battery cell group are gathered in a second direction, and then the first battery cell group and the second battery cell group are combined to obtain a stacked core;

[0040] (3) Repeat step (2) to make two stacked cores, which are respectively referred to as the first stacked core and the second stacked core;

[0041] (4) The first positive electrode ear and the second positive electrode ear of the first stacked core are respectively welded and fixed to the second side surface of the first bent portion of the first connecting sheet, and the first negative electrode ear and the second negative electrode ear are welded and fixed to the second side surface of the first bent portion of the second connecting sheet; the first positive electrode ear and the second positive electrode ear of the second stacked core are welded and fixed to the second side surface of the second bent portion of the first connecting sheet, and the first negative electrode ear and the second negative electrode ear are welded and fixed to the second side surface of the second bent portion of the second connecting sheet;

[0042] (5) folding the first stacked core and the second stacked core in a direction away from each other, and welding and fixing the cover plate assembly so that the cover plate assembly is respectively connected to the first connecting piece and the second connecting piece;

[0043] (6) The first bending portion and the second bending portion of the first connecting piece and the second connecting piece are bent for a second time, respectively, so that the first side surfaces of the first bending portion and the second bending portion fit the connecting body, thereby realizing the secondary core connection of the first core stack and the second core stack, and then the core stack is installed in a shell to obtain a high-capacity battery.

[0044] The preparation method provided by the present invention is easy to operate, avoids the problem of residual heat burns during welding of the connecting piece, reduces the loss of raw materials, simplifies the overall production process, and ensures the space utilization rate of the battery cavity.

[0045] As a preferred technical solution of the present invention, the secondary bending includes: using a folding knife to press the first bending portion or the second bending portion so that the first bending portion or the second bending portion is bent toward the side close to the second surface of the connecting body until it is in contact with the connecting body.

[0046] The thickness of the folding knife is 2 to 3 mm, for example, it can be 2 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, 2.5 mm, 2.6 mm, 2.7 mm, 2.8 mm, 2.9 mm or 3 mm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0047] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] The present invention provides a high-capacity battery and a preparation method thereof, which adopts a flexible and foldable connecting sheet design, reduces the height of the transfer tab, reduces the cost of the battery cell, and improves the space utilization rate of the shell. By ejecting a multi-tab stacking structure, the tab polarization is reduced, and the battery capacity is effectively improved, so that the battery capacity is as high as 630Ah. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 A schematic diagram of the appearance structure of a high-capacity battery provided by a specific embodiment of the present invention;

[0051] Figure 2 An exploded view of a high-capacity battery provided in accordance with one embodiment of the present invention;

[0052] Figure 2 (a) Figure 2 a bottom view of the cover assembly;

[0053] Figure 3 A schematic structural diagram of a first connecting sheet in an "initial state" provided for a specific embodiment of the present invention;

[0054] Figure 3 (a) is a side view of the first connecting piece in an "initial state";

[0055] Figure 3 (b) Figure 3 (a) A local enlarged view of point A;

[0056] Figure 4 A schematic structural diagram of a first connecting piece in an "intermediate state" provided for a specific embodiment of the present invention;

[0057] Figure 4 (a) is a side view of the first connecting piece in an "intermediate state";

[0058] Figure 5 A schematic structural diagram of a first connecting piece in a "completed state" provided for a specific embodiment of the present invention;

[0059] Figure 5 (a) is a side view of the first connecting piece in a "finished state";

[0060] Figure 6A schematic diagram of the structure of a battery module provided in a specific embodiment of the present invention;

[0061] Figure 7 A schematic diagram of a first positive electrode ear portion and a second positive electrode ear portion after being folded together, provided in a specific embodiment of the present invention;

[0062] Figure 8 A schematic diagram of a first positive electrode ear portion and a second positive electrode ear portion connected to a first connecting sheet provided in a specific embodiment of the present invention;

[0063] Figure 8 (a) Figure 8 A partial enlarged view of point B in the middle;

[0064] Fig. 9 A schematic diagram of a positive electrode tab and a negative electrode tab of a battery cell before being collapsed provided in a specific embodiment of the present invention;

[0065] Fig.10 A schematic diagram of a positive electrode tab of a battery cell before folding provided in a specific embodiment of the present invention;

[0066] Fig.11 A schematic diagram of a folded first positive electrode ear portion provided in a specific embodiment of the present invention;

[0067] Fig.12 A schematic structural diagram of a cover plate assembly provided in a specific embodiment of the present invention;

[0068] Fig.13 A schematic diagram of connecting a first core stack and a second core stack in parallel using a first connecting sheet and a second connecting sheet in a battery preparation process provided by a specific embodiment of the present invention;

[0069] Fig.13 (a) is a side view of a first core stack and a second core stack connected in parallel using a first connecting sheet and a second connecting sheet in a battery preparation process provided by a specific embodiment of the present invention;

[0070] Fig.14 A schematic diagram of folding a first core stack and a second core stack during a battery preparation process provided in a specific embodiment of the present invention;

[0071] Fig.15 A schematic diagram of a battery manufacturing process after welding a cover plate assembly according to a specific embodiment of the present invention;

[0072] Fig.16 A schematic diagram of welding of a cover plate assembly during battery preparation according to a specific embodiment of the present invention;

[0073] Fig.17A schematic diagram of a battery after secondary core assembly in a battery preparation process provided by a specific embodiment of the present invention;

[0074] Fig.18 A schematic diagram of a first pre-welding area provided for a specific embodiment of the present invention;

[0075] Fig.19 A schematic diagram of a second pre-welding area provided for a specific embodiment of the present invention;

[0076] Fig. 20 A schematic diagram of a secondary bending process provided for a specific embodiment of the present invention.

[0077] Among them, 1-first connecting piece; 2-cover assembly; 21-avoidance; 22-first battery cell pole; 3-first stacked core; 4-second stacked core; 31-first positive pole ear; 32-first negative pole ear; 41-second positive pole ear; 42-second negative pole ear; 5-protective layer; 6-supporting plate; 7-shell; 8-folding knife; 9-second connecting piece; 10-insulating layer; 12-connecting body; 112-accommodating convex bump; 113-anti-stupid corner; 114-arc opening; 115-thinning groove; 121-first bending portion; 131-second bending portion; 100-first battery cell group; 200-second battery cell group; 300-third battery cell group; 400-fourth battery cell group; A1, A2-positive pole ears; B1, B2-negative pole ears; S1-first pre-welding area; S2-second pre-welding area. DETAILED DESCRIPTION

[0078] It should be understood that, in the description of the present invention, the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0079] It should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "disposed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0080] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0081] In one embodiment, the present invention provides a high capacity battery such as Figure 1 , Figure 2 and Figure 2 As shown in (a), it includes a shell 7, a cover plate assembly 2, a first connecting plate 1, a second connecting plate 9 and a battery module. The battery module includes at least two stacked cores, and at least two of the stacked cores are stacked in sequence in the inner cavity of the shell 7. The stacked core is provided with a first adapter assembly and a second adapter assembly, and the first adapter assemblies of two adjacent stacked cores are connected in parallel through the first connecting plate 1, and the second adapter assemblies of two adjacent stacked cores are connected in parallel through the second connecting plate 9. Figure 3 , Figure 4 and Figure 5 As shown, the first connecting piece 1 and the second connecting piece 9 independently include a connecting body 12, and the connecting body 12 has a first surface and a second surface opposite to each other, the first surface is connected to the cover plate assembly 2, and the second surface is close to the stacked core. The two ends of the connecting body 12 are bent toward the second surface to form a first bending portion 121 and a second bending portion 131. The first bending portion and the second bending portion of the first connecting piece 1 are respectively connected to the first adapter assembly of two adjacent stacked cores, and the first bending portion and the second bending portion of the second connecting piece 9 are respectively connected to the second adapter assembly of two adjacent stacked cores.

[0082] The first adapter assembly and the second adapter assembly, the third adapter assembly and the fourth adapter assembly are all ejection structures, the first connecting piece 1 is used for the parallel connection of the positive electrode adapter assemblies of two adjacent stacked cores, and the second connecting piece 9 is used for the parallel connection of the negative electrode adapter assemblies of two adjacent stacked cores. Both the first connecting piece 1 and the second connecting piece 9 have a certain degree of softness and low hardness, and can be folded. The tensile strength of the first connecting piece 1 is 60-150MPa, the Vickers hardness is 20-35HV, and it has good elongation, which can meet the needs of various pressure processing, extension and bending. The Vickers hardness of the second connecting piece 9 is ≤70HV, and it has high current capacity, plasticity and ductility. Furthermore, the thickness of the first connecting piece 1 is greater than the thickness of the second connecting piece 9. The material of the first connecting piece 1 can be an aluminum material well known to those skilled in the art, such as 1060-O aluminum material. The material of the second connecting piece 9 can be a copper material well known to those skilled in the art, such as T2-M copper material. When the raw material has a high hardness, it can be annealed to meet the required softness requirements.

[0083] In some embodiments, Figure 4 and Figure 5 As shown, the first bending portion 121 and the second bending portion 131 independently have a first side surface and a second side surface opposite to each other; the first side surface of the first bending portion 121 fits the connecting body 12, and the second side surface of the first bending portion 121 is connected to the first adapter component or the second adapter component; the first side surface of the second bending portion 131 fits the connecting body 12, and the second side surface of the second bending portion 131 is connected to the first adapter component or the second adapter component. During the battery preparation process, those skilled in the art can adjust the bending angles of the first bending portion 121 and the second bending portion 131 according to different manufacturing steps. For example, Figure 4 As shown, when the first bending portion 121 and the second bending portion 131 are bent 90°, the first bending portion 121 and the second bending portion 131 are perpendicular to the plane where the connecting body 12 is located, and the first bending portion 121 and the second bending portion 131 are parallel to each other; Figure 5 As shown, when the first bending portion 121 and the second bending portion 131 are bent 180°, the first side surfaces of the first bending portion 121 and the second bending portion 131 are both attached to the connecting body 12, and the first bending portion 121 and the second bending portion 131 extend in opposite directions.

[0084] In some embodiments, Figure 3 , Figure 3 (a) with Figure 3As shown in (b), the surface of the connecting body 12 is provided with two thinning grooves 115, and the first bending portion 121 and the second bending portion 131 are formed by bending along the two thinning grooves 115. Specifically, the width of the thinning groove 115 is 3 to 4 mm, and the depth of the thinning groove 115 is 0.2 to 0.5 mm. The first connecting piece 1 and the second connecting piece 9 of the present invention are flat plate structures, and are bent along the reserved thinning grooves 115, which facilitates automated operation and improves the bending yield. Figure 4 (a) with Figure 5 (a) According to different preparation stages, the first connecting piece 1 and the second connecting piece 9 can be divided into an "initial state", an "intermediate state" and a "finished state". The "initial state" refers to an unbent flat state for easy loading; the "intermediate state" refers to a state in which the two ends of the connecting body 12 are bent 90° by two thinning grooves 115, that is, the first bending needle portion and the second bending portion 131 are parallel to each other and perpendicular to the connecting body 12; the "finished state" refers to a state in which the two ends of the connecting body 12 are bent 180° by two thinning grooves 115, that is, the first side surfaces of the first bending portion 121 and the second bending portion 131 are in contact with the second surface of the connecting body 12. Furthermore, two arc-shaped openings 114 arranged opposite to each other are provided on both sides of the connecting body 12 to avoid interference with the battery filling port.

[0085] In some embodiments, the stacked core includes a first battery cell group and a second battery cell group stacked in sequence, wherein the first battery cell group is provided with a first positive pole ear portion and a first negative pole ear portion gathered in a first direction at one end close to the cover plate assembly, and the second battery cell group is provided with a second positive pole ear portion and a second negative pole ear portion gathered in a second direction at one end close to the cover plate assembly, and the first direction is opposite to the second direction. The first positive pole ear portion is in a "U" shape, and the second positive pole ear portion is in an "S" shape, and is independently connected to the first connecting piece to form the first adapter assembly; the first negative pole ear portion is in a "U" shape, and the second negative pole ear portion is in an "S" shape, and is independently connected to the second connecting piece to form the second adapter assembly.

[0086] For example, the number of stacked cores in the battery module is two, which are respectively recorded as the first stacked core 3 and the second stacked core 4. Figure 6 As shown, the first core stack 3 includes a first battery cell group 100 and a second battery cell group 200 which are stacked in sequence, and the second core stack 4 includes a third battery cell group 300 and a fourth battery cell group 400 which are stacked in sequence.

[0087] The first battery cell group 100 is provided with a first positive electrode ear portion 31 and a first negative electrode ear portion 32 that are contracted along a first direction at one end of the first battery cell group 100 close to the cover plate assembly 2. The first battery cell group 100 is composed of a plurality of stacked battery cell units, and a stacked positive electrode ear A1 and a stacked negative electrode ear B1 are led out from the top of the battery cell unit. Figure 7 As shown, a plurality of laminated positive electrode tabs A1 are gathered along the first direction and welded to the same side to form a first positive electrode tab portion 31 which is initially in a conical folded shape, and a plurality of laminated negative electrode tabs B1 are gathered along the first direction and welded to the same side to form a first negative electrode tab portion 32 which is initially in a conical folded shape. The second battery cell group 200 is provided with a second positive electrode tab portion 41 and a second negative electrode tab portion 42 which are gathered along the second direction at one end close to the cover plate assembly 2. The second battery cell group 200 is composed of a plurality of stacked battery cell units, with a laminated positive electrode tab A2 and a laminated negative electrode tab B2 extending from the top of the battery cell unit. The plurality of laminated positive electrode tabs A2 are gathered along the second direction and welded to the same side to form a second positive electrode tab 41 that is initially in a conical folded shape. The plurality of laminated negative electrode tabs B2 are gathered along the second direction and welded to the same side to form a second negative electrode tab 42 that is initially in a conical folded shape. The first direction is opposite to the second direction. After being gathered, the first positive electrode tab 31 and the second positive electrode tab 41 are in an interval back-to-back structure in the initial state, and the first negative electrode tab 32 and the second negative electrode tab 42 are in an interval back-to-back structure in the initial state. After the first positive electrode tab 31 and the second positive electrode tab 41 are independently connected to the first bending portion 121 of the first connecting sheet 1, as shown in FIG. Figure 8 and Figure 8 As shown in (a), the first positive pole ear 31 is in a "U" shape, and the second positive pole ear 41 is in an "S" shape, forming the first adapter assembly. After the first negative pole ear 32 and the second negative pole ear 42 are independently connected to the first bent portion 121 of the second connecting piece 9, the first negative pole ear 32 is in a "U" shape, and the second negative pole ear 42 is in an "S" shape, forming the second adapter assembly.

[0088] The third battery cell group 300 is provided with a third positive pole ear and a third negative pole ear that are folded in the first direction at one end close to the cover plate assembly 2. The third battery cell group 300 is composed of a plurality of stacked battery cells, and the top of the battery cell leads to a laminated positive pole ear A1 and a laminated negative pole ear B1. The plurality of laminated positive pole ears A1 are folded in the first direction and welded to the same side to form a third positive pole ear that is initially in a conical folded shape. The plurality of laminated negative pole ears B1 are folded in the first direction and welded to the same side to form a third negative pole ear that is initially in a conical folded shape. The fourth battery cell group 400 is provided with a fourth positive pole ear and a fourth negative pole ear that are folded in the second direction at one end close to the cover plate assembly 2. The fourth battery cell group 400 is composed of a plurality of stacked battery cell monomers, and the top of the battery cell monomer leads to a laminated positive electrode tab A2 and a laminated negative electrode tab B2. The plurality of laminated positive electrode tabs A2 are gathered along the second direction and welded to the same side to form a fourth positive electrode tab portion that is initially in a conical folded shape. The plurality of laminated negative electrode tabs B2 are gathered along the second direction and welded to the same side to form a fourth negative electrode tab portion that is initially in a conical folded shape. The first direction is opposite to the second direction, and the third positive electrode tab portion and the fourth positive electrode tab portion in the initial state after being gathered are in a back-to-back structure with an interval, and the third negative electrode tab portion and the fourth negative electrode tab portion in the initial state after being gathered are in a back-to-back structure with an interval. After the third positive pole ear and the fourth positive pole ear are independently connected to the second bent portion 131 of the first connecting piece 1, the third positive pole ear is in a "U" shape, and the fourth positive pole ear is in an "S" shape, forming the third adapter assembly. After the third negative pole ear and the fourth negative pole ear are independently connected to the second bent portion 131 of the second connecting piece 9, the third negative pole ear is in a "U" shape, and the fourth negative pole ear is in an "S" shape, forming the fourth adapter assembly.

[0089] Specifically, Fig. 9 and Fig.10 As shown, the sizes of the positive pole tab A1 and the negative pole tab B1 of the first battery cell group 100, the second battery cell group 200, the third battery cell group 300 and the fourth battery cell group 400 before folding are the same, the width d3 of the positive pole tab A1 and the negative pole tab B1 are both 40-45 mm, and the height d2 are both 28-30 mm, wherein those skilled in the art can adjust the size of d3 according to the overcurrent value, and confirm the size of d2 based on the length of the tab required for assembly. Fig.11As shown, the height h1 of the positive pole ear (first positive pole ear 31, second positive pole ear 41, third positive pole ear and fourth positive pole ear) and the negative pole ear (first negative pole ear 32, second negative pole ear 42, third negative pole ear and fourth negative pole ear) formed after folding becomes 16-20 mm, and the folding value (the folding value refers to the linear distance between the outer surface of the folded pole ear and the extension line of the outer surface of the battery cell at the outermost side of the battery cell group) is 2.5-4 mm, which meets the requirement that each laminated pole ear can be welded and fixed. The height d1 of the battery cell is 190-195 mm.

[0090] Furthermore, the first direction is the extending direction of the first bending portion 121 when it is in a state of being fitted and connected to the main body 12, and the second direction is the extending direction of the second bending portion 131 when it is in a state of being fitted and connected to the main body 12, and the two are opposite.

[0091] In some embodiments, Figure 6 and Fig.12 As shown, the cover plate assembly 2 includes a top cover body, on which a first cell pole 22 and a second cell pole are arranged, the first cell pole 22 is partially located in the shell 7 and connected to the first connecting piece 1, and the second cell pole is partially located in the shell 7 and connected to the second connecting piece 9. An insulating layer 10 is provided around the surface of the top cover body close to the inner cavity of the shell 7, which is used to insulate the top cover assembly from the cell in the shell 7, the insulating layer 10 extends in the direction close to the inner cavity of the shell 7, and a gap is left between the insulating layer 10 and the outer edge of the connecting body 12.

[0092] The height of the first cell pole 22 and the second cell pole in the housing 7 is greater than the height of the insulating layer 10. Figures 3 to 5 As shown, the second surface of the connecting body 12 is provided with a receiving convex hump 112, and the receiving convex hump 112 protrudes toward the inner cavity of the shell 7. The end of the first battery cell pole 22 extending out of the insulating layer 10 is located in the receiving convex hump 112 of the first connecting piece 1; the end of the second battery cell pole extending out of the insulating layer 10 is located in the receiving convex hump 112 of the second connecting piece 9. The first surfaces of the first connecting piece 1 and the second connecting piece 9 of the present invention are recessed toward the inner cavity of the shell 7 to form a hollow receiving convex hump 112, and the receiving convex hump 112 cooperates with the raised portion of the bottom end surface of the battery cell pole on the cover plate assembly 2 to achieve positioning and connection between the cover plate assembly 2 and the connecting piece. Furthermore, an anti-stupid corner 113 is provided along the outer edge of the receiving convex hump 112.

[0093] like Fig.12As shown, in the first direction or the second direction, the distance x between the insulating layer 10 and the outer edge of the connecting body 12 is 1 to 2 mm. The insulating layer 10 is also provided with an escape opening 21, and the width D of the escape opening 21 is 15 to 18 mm. In the battery preparation process, after the cover plate assembly 2 is connected and fixed to the first connecting piece 1 and the second connecting piece 9 respectively, the first bending portion 121 and the second bending portion 131 of the connecting piece need to be further bent. Therefore, a pressure mechanism commonly used by technicians in this field is used to extend from the escape opening 21 to press the first bending portion 121 and the second bending portion 131 until the first side surfaces of the first bending portion 121 and the second bending portion 131 fit the connecting body 12.

[0094] In some embodiments, Figure 2 As shown, a support sheet 6 is further provided at the bottom of the inner cavity of the shell 7, and the support sheet 6 covers the bottom surface of the battery module to achieve insulation between the battery cell and the bottom of the shell 7. The present invention does not specifically limit the material of the support sheet 6, and any insulating material commonly used in the art can be used, such as polypropylene or polyethylene terephthalate.

[0095] In some embodiments, Figure 2 As shown, the inner cavity side wall of the shell 7 is also provided with a protective layer 5, and the protective layer 5 is arranged around the periphery of the battery module, and the two ends of the protective layer 5 are also connected to the insulating layer 10 and the support plate 6 respectively. The support plate 6 of the present invention is connected to the bottom end of the protective layer 5 by hot-melt welding, and the protective layer 5 is coated on the outer peripheral wall of the entire battery module. The insulating layer 10 on the cover plate assembly 2 is connected by hot-melt or bonding, and is assisted by tape to increase safety protection. The present invention does not specifically limit the material of the protective layer 5, and any insulating material commonly used in the art can be used, including but not limited to polyethylene terephthalate film or polypropylene film, preferably polyethylene terephthalate film.

[0096] In another specific embodiment, the present invention provides a method for preparing a high-capacity battery according to a specific embodiment, the preparation method comprising:

[0097] S1: connecting the first adapter components of two adjacent stacked cores in parallel using a first connecting sheet;

[0098] S2: connecting the second adapter assemblies of two adjacent stacked cores in parallel using a second connecting sheet;

[0099] S3: The first connecting piece and the second connecting piece are independently connected to the cover plate assembly, and then installed into the housing to obtain a high-capacity battery.

[0100] Exemplarily, when the number of stacked cores in the battery module is two, the preparation method specifically includes the following steps:

[0101] (1) Bend the first bending portion 121 and the second bending portion 131 of the first connecting piece 1 and the second connecting piece 9 once respectively, so that the first bending portion 121 and the second bending portion 131 are independently perpendicular to the plane where the connecting body 12 is located;

[0102] (2) The first positive electrode ear 31 and the first negative electrode ear 32 of the first battery cell group 100 are folded together in the first direction, and the second positive electrode ear 41 and the second negative electrode ear 42 of the second battery cell group 200 are folded together in the second direction; the third positive electrode ear and the third negative electrode ear of the third battery cell group 300 are folded together in the first direction, and the fourth positive electrode ear and the fourth negative electrode ear of the fourth battery cell group 400 are folded together in the second direction; then, the first battery cell group 100 and the second battery cell group 200 are combined once to obtain a first stacked core 3, and the third battery cell group 300 and the fourth battery cell group 400 are combined once to obtain a second stacked core 4;

[0103] (3) Fig.13 As shown, the first positive pole ear 31 and the second positive pole ear 41 are welded and fixed to the second side of the first bent portion 121 of the first connecting piece 1, and the first negative pole ear 32 and the second negative pole ear 42 are welded and fixed to the second side of the first bent portion 121 of the second connecting piece 9; the third positive pole ear and the fourth positive pole ear are welded and fixed to the second side of the second bent portion 131 of the first connecting piece 1, and the third negative pole ear and the fourth negative pole ear are welded and fixed to the second side of the second bent portion 131 of the second connecting piece 9;

[0104] (4) Fig.14 , Fig.15 and Fig.16 As shown, the first stacked core 3 and the second stacked core 4 are folded away from each other, and the cover plate assembly 2 is welded and fixed, so that the cover plate assembly 2 is connected to the first connecting piece 1 and the second connecting piece 9 respectively;

[0105] (5) Fig.17 As shown, the first bending portion 121 and the second bending portion 131 of the first connecting piece 1 and the second connecting piece 9 are bent twice, respectively, so that the first side surfaces of the first bending portion 121 and the second bending portion 131 fit the connecting body 12, thereby realizing the secondary core connection of the first stacked core 3 and the second stacked core 4, and then the batteries are installed in the shell 7 to obtain a high-capacity battery.

[0106] In step (1), the first connecting sheet 1 and the second connecting sheet 9 are connected as follows: Figure 3The material is loaded in the "initial state" shown in the figure, and after bending once along the two thinning grooves 115, the first connecting piece 1 and the second connecting piece 9 are both in the state as shown in the figure. Figure 4 The "intermediate state" shown.

[0107] In step (2), the first positive electrode ear 31, the first negative electrode ear 32, the second positive electrode ear 41, the second negative electrode ear 42, the third positive electrode ear, the third negative electrode ear, the fourth positive electrode ear and the fourth negative electrode ear are welded and fixed. Fig.13 and Fig.13 As shown in (a), since the first direction is opposite to the second direction, the pole ear portion of the folded first battery cell group 100 is spaced back to back with the pole ear portion of the second battery cell group 200, and the pole ear portion of the third battery cell group 300 is spaced back to back with the pole ear portion of the fourth battery cell group 400. While meeting the design and assembly requirements of multi-electrode ear stacking, the shortest pole ear height is obtained, and the pole ear height of the first stacked core 3 is consistent with that of the second battery cell, avoiding the occurrence of multiple specifications of pole ear die-cutting parameters. The present invention does not specifically limit the above-mentioned welding and fixing method, and any welding method known to those skilled in the art may be used, including but not limited to laser welding, ultrasonic welding, etc. Fig.18 As shown, those skilled in the art can set a first pre-welding area S1 on the pole ear for height positioning according to actual conditions, and the design specification of the first pre-welding area S1 is greater than the final welding weld mark specification. Specifically, the length d5 ​​of the first pre-welding area S1 is 16-20 mm, the width d6 is 6-10 mm, and the distance d7 from the bottom end of the first pre-welding area S1 to the bottom end of the pole ear is 8-10 mm. Ultrasonic welding is preferably used for welding and fixing of the pole ear, and the welding power of the first positive pole ear 31, the second positive pole ear 41, the third positive pole ear and the fourth positive pole ear is 1300-2300 W; the welding power of the first negative pole ear 32, the second negative pole ear 42, the third negative pole ear and the fourth positive and negative pole ears is 1500-2500 W.

[0108] In step (2), the primary cell joining includes: using adhesive tape to fit and fix the first cell group 100 and the second cell group 200, or the third cell group 300 and the fourth cell group 400.

[0109] In step (3), the first connecting sheet 1 and the second connecting sheet 9 are in an "intermediate state", and the first bending portion 121 and the second bending portion 131 of the first connecting sheet 1 are used to connect the positive pole ear portions of the first stacked core 3 and the second stacked core 4 in parallel; the first bending portion 121 and the second bending portion 131 of the second connecting sheet 9 are used to connect the negative pole ear portions of the first stacked core 3 and the second stacked core 4 in parallel, and the connection between the connecting sheet and the stacked core is achieved by welding and fixing, so that the first connecting sheet 1 and the second connecting sheet 9 are arranged side by side. The present invention does not specifically limit the above-mentioned welding and fixing method, and any welding method known to those skilled in the art may be used, including but not limited to laser welding, ultrasonic welding, etc. Fig.19 As shown, the present invention can set a second pre-welding area S2 on the second side of the first bend 121 and the second bend 131 for height positioning according to the actual flow value and the effective filtering area. Specifically, the length d8 of the second pre-welding area S2 is 12-16 mm, the width d9 is 4-8 mm, and the distance d10 from the bottom end of the second pre-welding area S2 to the bottom end of the bend is 9-11 mm. The welding fixation preferably adopts ultrasonic welding, and the welding power of the first connecting piece 1 is 2300-3200W, and the welding power of the second connecting piece 9 is 3500-4500W.

[0110] In step (4), if Fig.14 As shown, the first stacked core 3 and the second stacked core 4 are turned outward by 90°, so that the first stacked core 3 and the second stacked core 4 are located in the same plane. At this time, the first positive pole ear 31 and the first negative pole ear 32 gathered along the first direction on the first stacked core 3 are folded, and the second positive pole ear 41 and the second negative pole ear 42 gathered along the second direction on the second stacked core 4 are approximately unfolded; the third positive pole ear and the third negative pole ear gathered along the first direction on the third stacked core are folded, and the fourth positive pole ear and the fourth negative pole ear gathered along the second direction on the fourth stacked core are approximately unfolded. Subsequently, the cover plate assembly 2 is welded and fixed to the first surface of the connecting body 12, so that the first battery cell pole 22 is matched with the receiving protrusion on the first connecting piece 1, and the second battery cell pole is matched with the receiving protrusion on the second connecting piece 9, so that it is well positioned and does not occupy the inner cavity space of the shell 7.

[0111] In step (5), the secondary bending includes: Fig. 20As shown, the folding knife 8 is used to press the first bending portion 121 or the second bending portion 131, so that the first bending portion 121 or the second bending portion 131 is gradually bent along the path of a, a` and a`` toward one side of the second surface close to the connecting body 12 until it fits with the connecting body 12. Specifically, the thickness of the folding knife 8 is 2 to 3 mm. After completing the welding and fixing of the cover assembly 2, the operator can insert the folding knife 8 through the avoidance opening 21 of the insulating layer 10, press the first bending portion 121 and the second bending portion 131 to continue bending, and fit with the connecting body 12. At this time, the first positive pole ear 31 and the first negative pole ear 32 on the first stacked core 3 that are gathered along the first direction are in a "U" shape, and the second positive pole ear 41 and the second negative pole ear 42 on the second stacked core 4 that are gathered along the second direction are in an "S" shape; the third positive pole ear and the third negative pole ear on the third stacked core that are gathered along the first direction are in a "U" shape, and the fourth positive pole ear and the fourth negative pole ear on the fourth stacked core that are gathered along the second direction are in an "S" shape.

[0112] In step (5), the secondary core bonding includes: using tape to bond and fix the first core stack 3 and the second core stack 4, that is, as the first bending portion 121 and the second bending portion 131 are folded flat, the second battery cell group 200 and the third battery cell group 300 are bonded.

[0113] In step (5), before the housing 7 is installed, the support plate 6 and the protective layer 5 are made by hot-melt welding in the inner cavity of the housing 7. During the installation process of the housing 7, a pressure mechanism commonly used in the art is used to apply pressure until the cover plate assembly 2 matches the housing 7. After the installation is completed, the outer periphery of the top cover body is fixed to the housing 7 by welding.

[0114] The battery of the present invention adopts a multi-stage ear stacking structure with a small polarization of the pole ear. Through four-core assembly, the turnover of the battery cell is convenient. At the same time, the soft design of the connecting piece improves the current carrying capacity. According to different production requirements, the connecting piece is converted into different bending states to meet the assembly production requirements, and the height of the pole ear required for multi-stage ear welding is also minimized, thereby reducing the cost of the battery cell, optimizing the battery weight, and making the structure compact, thereby improving the utilization rate of the inner cavity of the shell 7.

[0115] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A high capacity battery, characterized in that: The high-capacity battery comprises a shell, a cover plate assembly, a first connecting plate, a second connecting plate and a battery module; the battery module comprises at least two stacked cores, and at least two stacked cores are sequentially stacked in the inner cavity of the shell; an opening is formed at the top of the shell, and the cover plate assembly is arranged at the opening; The stacked core is provided with a first adapter assembly and a second adapter assembly, the first adapter assemblies of two adjacent stacked cores are connected in parallel via the first connecting piece, and the second adapter assemblies of two adjacent stacked cores are connected in parallel via the second connecting piece; The first connecting piece and the second connecting piece independently include a connecting body, and the connecting body has a first surface and a second surface relative to each other, the first surface is connected to the cover plate assembly, and the second surface is close to the stacked core; both ends of the connecting body are bent toward the second surface to form a first bending portion and a second bending portion, the first bending portion and the second bending portion of the first connecting piece are respectively connected to the first adapter components of the two adjacent stacked cores, and the first bending portion and the second bending portion of the second connecting piece are respectively connected to the second adapter components of the two adjacent stacked cores.

2. The high capacity battery according to claim 1, characterized in that: The first bending portion and the second bending portion independently have a first side surface and a second side surface opposite to each other; The first side surface of the first bending portion is in contact with the connecting body, and the second side surface of the first bending portion is connected to the first adapter component or the second adapter component; The first side surface of the second bending portion is in contact with the connecting body, and the second side surface of the second bending portion is connected to the first adapter component or the second adapter component.

3. The high capacity battery according to claim 2, characterized in that: The stacked core comprises a first battery cell group and a second battery cell group stacked in sequence, wherein one end of the first battery cell group close to the cover plate assembly is provided with a first positive pole ear portion and a first negative pole ear portion gathered along a first direction, and one end of the second battery cell group close to the cover plate assembly is provided with a second positive pole ear portion and a second negative pole ear portion gathered along a second direction, and the first direction is opposite to the second direction; The first positive pole ear is in a "U" shape, the second positive pole ear is in an "S" shape, and is independently connected to the first connecting piece to form the first adapter assembly; the first negative pole ear is in a "U" shape, the second negative pole ear is in an "S" shape, and is independently connected to the second connecting piece to form the second adapter assembly.

4. The high capacity battery according to claim 1, characterized in that: The cover plate assembly includes a top cover body, on which a first battery cell pole and a second battery cell pole are arranged, the first battery cell pole portion is located in the shell and connected to the first connecting piece, and the second battery cell pole portion is located in the shell and connected to the second connecting piece; An insulating layer is provided around the surface of the top cover body on a side close to the inner cavity of the shell, and the insulating layer extends toward the inner cavity of the shell; A gap is left between the insulating layer and the outer edge of the connecting body.

5. The high capacity battery according to claim 4, characterized in that: The height of the first battery cell pole and the second battery cell pole in the shell is greater than the height of the insulating layer; The second surface of the connecting body is provided with a receiving convex bump, and the receiving convex bump protrudes toward the inner cavity of the shell; The end of the first battery cell pole extending out of the insulating layer is located in the receiving convex bump of the first connecting piece; The end of the second battery cell pole extending out of the insulating layer is located in the receiving convex bump of the second connecting piece; In the first direction or the second direction, the linear distance between the insulating layer and the outer edge of the connecting body is 1 to 2 mm; The insulating layer is also provided with an escape opening.

6. The high capacity battery according to claim 5, characterized in that: The surface of the connecting body is provided with two thinning grooves, and the first bending portion and the second bending portion are formed by bending along the two thinning grooves respectively; The width of the thinning groove is 3 to 4 mm, and the depth of the thinning groove is 0.2 to 0.5 mm; Two arc-shaped openings arranged opposite to each other are formed on both sides of the connecting body; An anti-stuck corner is arranged along the outer edge of the accommodating convex bump.

7. The high capacity battery according to claim 5, characterized in that: A supporting plate is also provided at the bottom of the inner cavity of the shell; The inner cavity side wall of the shell is also provided with a protective layer, and the protective layer is arranged around the periphery of the battery module. The two ends of the protective layer are also connected to the insulating layer and the supporting plate respectively.

8. A method for preparing a high-capacity battery according to any one of claims 1 to 7, characterized in that: The preparation method comprises: The first adapter components of two adjacent stacked cores are connected in parallel by using a first connecting sheet; The second adapter components of two adjacent stacked cores are connected in parallel by using a second connecting piece; The first connecting piece and the second connecting piece are independently connected to the cap plate assembly and then installed into a shell to obtain a high-capacity battery.

9. The preparation method according to claim 8, characterized in that: The preparation method comprises the following steps: (1) bending the first bending portion and the second bending portion of the first connecting piece and the second connecting piece respectively, so that the first bending portion and the second bending portion are independently perpendicular to the plane where the connecting body is located; (2) the first positive electrode ear and the first negative electrode ear of the first battery cell group are gathered in a first direction, and the second positive electrode ear and the second negative electrode ear of the second battery cell group are gathered in a second direction, and then the first battery cell group and the second battery cell group are combined to obtain a stacked core; (3) Repeat step (2) to make two stacked cores, which are respectively referred to as the first stacked core and the second stacked core; (4) The first positive electrode ear and the second positive electrode ear of the first stacked core are respectively welded and fixed to the second side surface of the first bent portion of the first connecting sheet, and the first negative electrode ear and the second negative electrode ear are welded and fixed to the second side surface of the first bent portion of the second connecting sheet; the first positive electrode ear and the second positive electrode ear of the second stacked core are welded and fixed to the second side surface of the second bent portion of the first connecting sheet, and the first negative electrode ear and the second negative electrode ear are welded and fixed to the second side surface of the second bent portion of the second connecting sheet; (5) folding the first stacked core and the second stacked core in a direction away from each other, and welding and fixing the cover plate assembly so that the cover plate assembly is respectively connected to the first connecting piece and the second connecting piece; (6) The first bending portion and the second bending portion of the first connecting piece and the second connecting piece are bent for a second time, respectively, so that the first side surfaces of the first bending portion and the second bending portion fit the connecting body, thereby realizing the secondary core connection of the first core stack and the second core stack, and then the core stack is installed in a shell to obtain a high-capacity battery.

10. The preparation method according to claim 9, characterized in that: The secondary bending includes: using a folding knife to press the first bending portion or the second bending portion so that the first bending portion or the second bending portion is bent toward a side close to the second surface of the connecting body until it fits with the connecting body; The thickness of the folding knife is 2-3 mm.

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