Wound battery cell structure

Abstract

A wound battery cell structure comprises a cathode sheet (21), a first separator (31), an anode sheet (22), a second separator (32), a first connecting sheet (11) arranged at a starting end and connecting the cathode sheet (21) and the first separator (31), a third connecting sheet (13) connecting the anode sheet (22) and the second separator (32), a second connecting sheet (12) arranged at an ending end and connecting the cathode sheet (21) and the first separator (31), and a fourth connecting sheet (14) connecting the anode sheet (22) and the second separator (32), wherein the cathode sheet (21), the first separator (31), the anode sheet (22), the second separator (32), the first connecting sheet (11), the third connecting sheet (13), the second connecting sheet (12), and the fourth connecting sheet (14) are stacked in sequence and wound. The first separator (31), the second separator (32), the first connecting sheet (11), and the third connecting sheet (13) are aligned at the starting end, and the first separator (31), the second separator (32), the second connecting sheet (12), and the fourth connecting sheet (14) are aligned at the ending end. The wound battery cell structure provided by the present application has excellent electrical performance and can be prepared efficiently.

Description

A wound battery core structure

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application number 2024202880575, filed with the Patent Office of China on February 6, 2024, entitled “A Wound Battery Cell Structure”; the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the technical field of battery winding, and in particular to a wound battery cell structure. Background Art

[0004] In the structure of a wound battery cell, the cathode, anode, and separator must be designed with different lengths in the free state in a single cell, that is, the starting ends of the cathode, anode, and separator in the inner ring of the wound battery cell cannot be aligned, and the tail ends of the cathode, anode, and separator in the outer ring of the wound battery cell cannot be aligned. Therefore, during the production and winding process of existing wound batteries, the cathode, anode, and separator need to be accelerated and decelerated, causing the three to be misaligned. This inevitably leads to a decrease in the production speed of the wound battery cell during the production and winding process; the tension of the cathode sheet, anode sheet, and separator is different, and the consistency of the tightness between the multi-layer structure formed by winding is poor, which is not conducive to stable product quality; and the heads and tails of the cathode and anode sheets are directly exposed in the winding core, which is prone to problems such as burrs and powder loss of the electrode sheets.

[0005] Application Contents

[0006] One of the purposes of the present application is to provide a wound battery cell with good tension consistency among the cathode sheet, anode sheet and separator.

[0007] The present application discloses a wound battery cell structure, comprising: a cathode sheet, a first separator, an anode sheet, and a second separator stacked and wound in sequence; the cathode sheet is shorter than the anode sheet, and the anode sheet is shorter than the first separator and the second separator;

[0008] The battery cell further comprises a first connecting piece, a second connecting piece, a third connecting piece, and a fourth connecting piece; the first connecting piece and the third connecting piece are connected to the first separator and the second separator at portions close to the rolling end of the wound battery cell structure; and the first connecting piece is connected to the rolling end of the cathode sheet at a portion close to the rolling end of the cathode sheet, and the third connecting piece is connected to the rolling end of the anode sheet at a portion close to the rolling end of the anode sheet;

[0009] The parts of the second connecting piece and the fourth connecting piece close to the winding end of the wound battery cell structure are combined with the first diaphragm and the second diaphragm; and the part of the second connecting piece close to the tail end of the cathode piece is combined with the tail end of the cathode piece, and the part of the fourth connecting piece close to the tail end of the anode piece is combined with the tail end of the anode piece.

[0010] Furthermore, in some embodiments of the present application, the portions of the first connecting sheet and the third connecting sheet close to the rolling end of the wound cell structure are combined with the first separator and the second separator to form a rolling end joint; the portion of the first connecting sheet close to the rolling end of the cathode sheet is combined with the rolling end of the cathode sheet to form a first joint; the portion of the third connecting sheet close to the rolling end of the anode sheet is combined with the rolling end of the anode sheet to form a second joint; there is a gap between the rolling end joint and the first joint and the second joint;

[0011] The parts of the second connecting piece and the fourth connecting piece close to the tail end of the wound battery cell structure are combined with the first diaphragm and the second diaphragm to form a tail end joint; the part of the second connecting piece close to the tail end of the cathode piece is combined with the tail end of the cathode piece to form a third joint; the part of the fourth connecting piece close to the tail end of the anode piece is combined with the tail end of the anode piece to form a fourth joint; there is a gap between the tail end joint and the third joint and the fourth joint.

[0012] Furthermore, in some embodiments of the present application, the end of the first connecting piece away from the cathode piece is flush with the rolled-up end of the first diaphragm, the rolled-up end of the second diaphragm, and the end of the third connecting piece away from the anode piece;

[0013] The offset between the end of the second connecting piece away from the cathode piece and the tail end of the first diaphragm, the tail end of the second diaphragm, and the end of the fourth connecting piece away from the anode piece does not exceed 10 mm.

[0014] Furthermore, in some embodiments of the present application, the first connecting sheet, the second connecting sheet, the third connecting sheet and the fourth connecting sheet are all porous connecting sheets.

[0015] Furthermore, in some embodiments of the present application, the porosity of the porous connecting sheet is 15-70%, and the average pore size is 10-50 μm.

[0016] Furthermore, in some embodiments of the present application, the first connecting piece, the second connecting piece, the third connecting piece and the fourth connecting piece are all made of the same material as the diaphragm connecting piece.

[0017] Furthermore, in some embodiments of the present application, the length of the connection between the first connecting piece and the starting end of the cathode sheet is no greater than 1.5 times the circumference of the winding needle used to wind the wound battery cell structure; the length of the connection between the third connecting piece and the starting end of the anode sheet is no greater than 1.5 times the circumference of the winding needle used to wind the wound structure;

[0018] and / or

[0019] The length of the connection between the second connecting piece and the tail end of the cathode piece is at most 1.5 times the circumference of the outer ring of the battery cell; the length of the connection between the fourth connecting piece and the tail end of the anode piece is at most 1.5 times the circumference of the outer ring of the battery cell.

[0020] Furthermore, in some embodiments of the present application, the length of the portion of the third connecting piece combined with the second diaphragm is no greater than 10 mm; the length of the portion of the fourth connecting piece not combined with the anode piece is no greater than 10 mm.

[0021] Furthermore, in some embodiments of the present application, the wound cell structure is provided with a first straight section and a first corner section from the starting end to the ending end; the first corner section includes a first connecting sheet, a first diaphragm, an anode sheet, and a second diaphragm stacked in sequence;

[0022] The first straight section includes a first connecting piece, a second diaphragm, a second connecting piece, and a second diaphragm stacked in sequence.

[0023] Furthermore, in some embodiments of the present application, the widths of the first connecting piece, the second connecting piece, the third connecting piece, and the fourth connecting piece are not less than 95% of the width of the electrode piece and not greater than the width of the diaphragm.

[0024] Further, in some embodiments of the present application, the first connecting piece includes a first connecting piece A and a first connecting piece B; the first connecting piece A and the first connecting piece B are respectively located on both sides of the rolled end of the cathode piece and connected to the rolled end of the cathode piece; and / or

[0025] The second connecting piece includes a second connecting piece A and a second connecting piece B; the second connecting piece A and the second connecting piece B are respectively located on both sides of the tail end of the cathode piece and connected to the tail end of the cathode piece; and / or

[0026] The third connecting piece includes a third connecting piece A and a third connecting piece B; the third connecting piece A and the third connecting piece B are respectively located on both sides of the rolling end of the anode piece and connected to the rolling end of the anode piece; and / or

[0027] The fourth connecting piece includes a fourth connecting piece A and a fourth connecting piece B; the fourth connecting piece A and the fourth connecting piece B are respectively located on both sides of the tail end of the anode piece and connected to the tail end of the anode piece;

[0028] The first connecting piece A, the first connecting piece B, the third connecting piece A and the third connecting piece B are aligned at one end away from the rolling end of the cathode piece; the second connecting piece A, the second connecting piece B, the fourth connecting piece A and the fourth connecting piece B are aligned at one end away from the tailing end of the cathode piece.

[0029] Furthermore, in some embodiments of the present application, a first protective sticker is provided at the connection between the first connecting sheet and the rolled-up end of the cathode sheet, wherein the first protective sticker is partially connected to the first connecting sheet and partially connected to the cathode sheet; a second protective sticker is connected at the connection between the second connecting sheet and the tail end of the cathode sheet, such that the second protective sticker is partially connected to the second connecting sheet and partially connected to the cathode sheet;

[0030] A third protective sticker is provided at the connection between the third connecting piece and the rolled end of the anode sheet, and the third protective sticker is partially connected to the third connecting piece and partially connected to the anode sheet; a fourth protective sticker is connected at the connection between the fourth connecting piece and the tail end of the anode sheet, so that the fourth protective sticker is partially connected to the fourth connecting piece and partially connected to the anode sheet.

[0031] Beneficial effects of this application:

[0032] The present application provides a new wound cell structure, which is provided with connecting pieces on the inner winding end and the outer winding end of the wound cell, and the length difference of the cathode sheet, the anode sheet and the diaphragm is supplemented by the connecting pieces, so that in the winding process, four layers of the same length and stacked layer structure are actually rolled and wound at the same time, avoiding the different tensions caused by the cathode sheets, anode sheets and diaphragms of different lengths being rolled in and wound asynchronously at the same time, thereby improving the tension consistency between the layers in the wound cell structure; at the same time, due to the first connecting piece and the rolling end of the first diaphragm, the third connecting piece and the first diaphragm and the rolling end of the second diaphragm, the second connecting piece and the ending end of the first diaphragm, the fourth connecting piece and the The tail end of the first diaphragm is connected to the tail end of the second diaphragm, forming a coating on both ends of the cathode and anode sheets, improving or even avoiding the problem of burrs and powder falling on the electrode sheets; in addition, the first connecting sheet connects the first diaphragm and the cathode sheet together, and the second connecting sheet connects the first diaphragm, the second diaphragm and the cathode sheet together, thereby forming the cathode sheet, the first diaphragm, the anode sheet and the second diaphragm to form a whole at the winding end, so that during the winding process, the cathode sheet, the first diaphragm, the anode sheet and the second diaphragm can be driven to move at the same time, with the same winding state, and no displacement difference will be generated during the winding process, further reducing the possibility of tension fluctuations and wrinkles, and helping to control the stability of the spacing between layers. Moreover, since the winding end and the tail end are actually a four-layer structure formed by the connecting sheet and the diaphragm, the structure of the inner ring head end and the outer ring tail end of the wound battery structure is more controllable and the performance stability is better.

[0033] The wound battery cell provided in the present application has the cathode sheet, the first diaphragm, the anode sheet and the second diaphragm whose rolling ends are connected together and can be wound synchronously. Therefore, the wound battery cell structure is suitable for preparation by high-speed winding process, and can be suitable for winding feeding speeds of more than 600 mm / s or even more than 2000 mm / s, which can achieve efficient production and preparation. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG1 is a schematic structural diagram of a wound battery cell structure provided by some embodiments of the present application;

[0035] FIG2 is a schematic structural diagram of a wound battery cell structure provided in some embodiments of the present application;

[0036] FIG3 is a schematic diagram of the joints of a first connecting sheet, a cathode sheet, a first separator, a second connecting sheet, a third connecting sheet, an anode sheet, a second separator, and a fourth connecting sheet in a wound battery cell structure according to some embodiments of the present application;

[0037] Among them, 11-first connecting piece, 111-first connecting piece A, 121-first connecting piece B, 12-second connecting piece, 121-second connecting piece A, 122-second connecting piece B, 13-third connecting piece, 131-third connecting piece A, 132-third connecting piece B, 14-fourth connecting piece, 141-fourth connecting piece A, 142-fourth connecting piece B, 21-cathode piece, 22-anode piece, 31-first diaphragm, 32-second diaphragm, 4-tail glue; 51-rolling end joint, 52-tailing end joint, 53-first joint, 54-second joint, 55-third joint, 56-fourth joint. DETAILED DESCRIPTION

[0038] In order to better explain the present application, the present application is described in detail with reference to the implementation methods of the present application, and the main content of the present application is further clarified in combination with specific examples, but the content of the present application is not limited to the following examples.

[0039] In the description of this application, it should be understood that the terms "thickness," "upper," "lower," and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of this application and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the term "plurality" means two or more, unless otherwise specifically defined.

[0040] The disclosure below provides many different embodiments or examples for realizing different structures of the present application. In order to simplify the disclosure of the present application, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present application. In addition, the present application may repeat reference numbers and / or reference letters in different examples, and such repetition is for the purpose of simplicity and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present application provides examples of various specific processes and materials, but those of ordinary skill in the art will appreciate the application of other processes and / or the use of other materials.

[0041] In the prior art, since wound battery cells are formed by winding a stacked cathode sheet, a first separator, an anode sheet, and a second separator, and since the starting and ending ends of the cathode sheet, the first separator / second separator, and the anode sheet are not aligned, their respective winding and rewinding times are different, which easily makes it difficult to control the tension of the cathode sheet, the first separator, the anode sheet, and the second separator during winding, which in turn causes defects such as wrinkles and bends in the wound battery cell. These defects can cause a large number of wrinkles on the battery electrode due to repeated expansion and contraction during the charge and discharge process, limiting capacity and potentially causing problems such as lithium analysis. Therefore, how to control the tension of the wound battery cell during the winding process has become one of the keys to wound battery cell quality control.

[0042] Based on this technical problem, the present application proposes a wound cell structure, as shown in Figures 1 and 2, comprising: a cathode sheet 21, a first separator 31, an anode sheet 22, and a second separator 32 stacked and wound in sequence; the length of the cathode sheet 21 is shorter than the anode sheet 22, and the length of the anode sheet 22 is shorter than the first separator 31 and the second separator 32, so that the cathode sheet 21, the anode sheet 22, and the separator still maintain the non-aligned structure in the wound cell design;

[0043] The battery pack further includes a first connecting piece 11, a second connecting piece 12, a third connecting piece 13 and a fourth connecting piece 14; the first connecting piece 11 and the third connecting piece 13 are connected to the first diaphragm 31 and the second diaphragm 32 near the rolling end of the wound battery cell structure; and the first connecting piece 11 is connected to the rolling end of the cathode sheet 21, and the third connecting piece 13 is connected to the rolling end of the anode sheet 22; the second connecting piece 12 and the fourth connecting piece 14 are connected to the first diaphragm 31 and the second diaphragm 32 near the rolling end of the wound battery cell structure; The membrane 31 is combined with the second diaphragm 32; and the part of the second connecting piece 12 close to the tail end of the cathode piece 21 is combined with the tail end of the cathode piece 21, and the part of the fourth connecting piece 14 close to the tail end of the anode piece 22 is combined with the tail end of the anode piece 22; the rolled end of the cathode piece 21 is connected to the first connecting piece 11, and the tail end is connected to the second connecting piece 12; the rolled end of the anode piece 22 is connected to the third connecting piece 13, and the tail end is connected to the fourth connecting piece 14; and part of the first connecting piece 11 is combined with the first diaphragm 31, and part of the third connecting piece 13 is combined with the second diaphragm 32.

[0044] As shown in Figure 3, the parts of the first connecting piece and the third connecting piece close to the rolling end of the wound battery cell structure are combined with the first diaphragm and the second diaphragm to form a rolling end joint 51; the part of the first connecting piece close to the rolling end of the cathode piece is combined with the rolling end of the cathode piece to form a first joint 53; the part of the third connecting piece close to the rolling end of the anode piece is combined with the rolling end of the anode piece to form a second joint 54; there are gaps between the rolling end joints and the first and second joints; that is, there is a region between the rolling end joint and the first joint, where the first connecting piece is not combined with the cathode piece, the anode piece, the first diaphragm and the second diaphragm; and there is a region between the rolling end joint and the second joint, where the second connecting piece is not combined with the cathode piece, the anode piece, the first diaphragm and the second diaphragm.

[0045] The parts of the second connecting piece and the fourth connecting piece close to the tail end of the wound battery cell structure are combined with the first diaphragm and the second diaphragm to form a tail end joint 52; the part of the second connecting piece close to the tail end of the cathode piece is combined with the tail end of the cathode piece to form a third joint 55; the part of the fourth connecting piece close to the tail end of the anode piece is combined with the tail end of the anode piece to form a fourth joint 56; there are gaps between the tail end joint and the third joint and the fourth joint, that is, there is an area between the tail end joint and the third joint where the first connecting piece is not combined with the cathode piece, anode piece, first diaphragm and second diaphragm, and there is an area between the tail end joint and the fourth joint where the second connecting piece is not combined with the cathode piece, anode piece, first diaphragm and second diaphragm.

[0046] It should be noted that the “combination” in this application refers to the connection between the two combined structures in a certain way, and requires the application of forces other than gravity or processing procedures to separate the two, and does not mean contact.

[0047] The end of the first connecting piece 11 away from the cathode piece 21 is nearly flush with the rolled end of the first diaphragm 31, the rolled end of the second diaphragm 32, and the end of the third connecting piece 13 away from the anode piece 22.

[0048] The second connecting piece 12 is combined with the first diaphragm 31, the fourth connecting piece 14 is combined with the second diaphragm 32, and the end of the second connecting piece 12 away from the cathode piece 21 is nearly flush with the tail end of the first diaphragm 31, the tail end of the second diaphragm 32, and the end of the fourth connecting piece 14 away from the anode piece 22. Exemplarily, the offset of the end of the second connecting piece away from the cathode piece and the tail end of the first diaphragm, the tail end of the second diaphragm, and the end of the fourth connecting piece away from the anode piece does not exceed 10 mm.

[0049] In the present application, since the end faces of the first connecting piece, the second connecting piece, the third connecting piece, the fourth connecting piece, the first diaphragm and the second diaphragm at the tail end and the starting end of the wound battery cell structure are formed by cutting, they are actually very close to being flush when cut. During the winding process, the winding process will cause the second connecting piece, the fourth connecting piece, the first diaphragm and the second diaphragm at the tail end of the wound battery cell structure to have natural slight deviations, and thus appear to be not completely flush.

[0050] In the present application, since the first connecting piece, the third connecting piece, the rolling end of the first diaphragm, and the rolling end of the second diaphragm are flush; the second connecting piece, the fourth connecting piece, the tail end of the first diaphragm, and the tail end of the second diaphragm are flush, and the first connecting piece is connected to the rolling end of the cathode piece, the third connecting piece is connected to the rolling end of the anode piece, the second connecting piece is connected to the tail end of the cathode piece, and the fourth connecting piece is connected to the tail end of the anode piece, the length difference between the cathode piece and the first diaphragm at the rolling end, the length difference between the anode piece and the second diaphragm at the rolling end, and the cathode piece are connected to the tail end of the anode piece. The length difference between the cathode sheet and the first separator at the end, and the length difference between the anode sheet and the second separator at the end are made up, forming a structure in which the starting end of the wound battery cell is flush and the ending end is nearly flush. Therefore, when the cathode sheet, the first separator, the anode sheet, and the second separator are fed in substantially at the same time during the start-up; when the cathode sheet, the first separator, the anode sheet, and the second separator are also reeled in substantially at the same time. In other words, during the entire winding process, the states of the cathode sheet, the first separator, the anode sheet, and the second separator are approximately the same, facilitating the tension control of each layer. In fact, the tension is also controlled to be the same or approximately the same, making it difficult for each layer, especially the cathode sheet and / or the anode sheet, to bend or wrinkle, providing a basis for the stable performance of the wound battery cell.

[0051] Furthermore, because the first connecting piece is partially connected to the cathode sheet and located on the side of the cathode sheet away from the first separator, and another portion is connected to the first separator, a structure is formed that covers the cathode sheet at the start of the roll, thereby preventing the loss of metal or non-metallic powder and fragments from the severed cathode sheet. Similarly, the third connecting piece is partially connected to the anode sheet and located on the side of the anode sheet located on the second separator, and another portion is connected to the second separator, also forming a structure that covers the anode sheet at the start of the roll, thereby preventing the loss of metal or non-metallic powder and fragments from the severed anode sheet.

[0052] In some embodiments, the first, second, third, and fourth connecting sheets are all porous connecting sheets, which can prevent bubbles from forming at the connections between the first, second, third, and fourth connecting sheets and the electrode sheets (cathode sheets / anode sheets) and the diaphragm (first diaphragm / second diaphragm) when they are combined. Even if some tiny bubbles appear, they are easily discharged through the pores, thereby preventing bubbling and delamination at the connections between the first, second, third, and fourth connecting sheets and the electrode sheets and diaphragm during operation of the battery cell, which can lead to a rapid decline in battery performance. At the same time, the porous structure of the connecting sheets (first, second, third, and fourth connecting sheets) can also provide ion transmission channels.

[0053] It should be noted that the porous structure of the porous connecting sheet used in the present application is a porous structure with an average pore size of micrometer level and relatively uniform pore distribution.

[0054] Preferably, the porous connecting sheet has a porosity of 15-70% and an average pore size of 10-50 μm. Preferably, the porosity is 20-50% and the average pore size is 10-30 μm to ensure the strength and ion permeability of the connecting sheet.

[0055] Preferably, the porosity and average pore size of the porous connecting sheet are the same as or close to those of the diaphragm.

[0056] More preferably, the materials of the first connecting piece, the second connecting piece, the third connecting piece and the fourth connecting piece are all the same diaphragm connecting piece as the diaphragm. Its thickness is the same as that of the diaphragm or less than that of the diaphragm, reducing the increase in the thickness of the battery cell structure caused by the connecting piece. In this embodiment, since the connecting piece is made of the same material as the diaphragm, its porosity and average pore size are the same or similar, and its elastic modulus is also the same or similar to that of the diaphragm, so that the tension between the connecting piece and the electrode and the diaphragm during the winding process is the same or similar to the tension of the diaphragm, which can further reduce the formation of bubbles between the diaphragm connecting piece and the electrode, and the connector and the diaphragm, and can also improve the bending of the electrode, further ensuring or even improving the electrical performance and quality stability of the wound battery cell. Moreover, since the diaphragm connecting piece and the diaphragm are film layers of the same material, the wound battery cell formed by its winding does not actually introduce film layers of other materials / structures, so the performance of the wound battery cell formed by its winding will not be affected by the introduction of other materials / structures.

[0057] In some embodiments, the length of the connection between the first connecting piece and the winding end of the cathode piece is no greater than 1.5 times the circumference of the winding needle used to wind the wound battery cell structure. It is understood that the length of the connection is ≤ 1.5 times the circumference. The length of the connection between the third connecting piece and the winding end of the anode piece is no greater than 1.5 times the circumference of the winding needle used to wind the winding structure. It is understood that the length of the connection is ≤ 1.5 times the circumference. This prevents the anode and cathode pieces from contacting the winding needle during the winding process of the battery cell, thereby avoiding the performance impact caused by the contact between the cathode and cathode pieces and the winding needle.

[0058] The length of the second connecting tab joined to the cathode tab's tail is no more than 1.5 times the cell's outer circumference; the length of the fourth connecting tab joined to the anode tab's tail is no more than 1.5 times the cell's outer circumference. In some embodiments, the length of the first connecting tab joined to the first separator is no greater than 40 mm; the length of the second connecting tab joined to the first separator is no greater than 100 mm or no greater than the core width; the length of the third connecting tab joined to the second separator is no greater than 30 mm; and the length of the portion of the fourth connecting tab not joined to the anode tab is no greater than 30 mm.

[0059] Preferably, in some embodiments of the present application, the length of the third connecting tab joining the second separator is no greater than 10 mm, and the length of the portion of the fourth connecting tab not joining the anode tab is no greater than 10 mm. More preferably, the length of the third connecting tab joining the second separator can be controlled within 5 mm, and the length of the portion of the fourth connecting tab not joining the anode tab can be controlled within 5 mm, thereby improving the utilization of various structures in the wound cell and the efficiency of its winding production.

[0060] In some embodiments, the wound battery cell structure is provided with a first straight section and a first corner section from the starting end to the ending end; the first straight section includes a first connecting piece, a second diaphragm, a second connecting piece and a second diaphragm stacked in sequence; the first corner section includes a first connecting piece, a first diaphragm, an anode piece and a second diaphragm stacked in sequence; the first connecting piece is connected to the first diaphragm in the first corner section, which has the same effect as the protective adhesive layer, so that the wound battery cell can omit the setting of the protective adhesive layer at the first corner section, reduce the gluing process of the protective adhesive layer, and further improve the winding preparation efficiency.

[0061] It should be noted that a tail glue 4 is also provided at the tail end of the wound battery cell structure, part of the tail glue 4 is combined with the tail joint formed by the second connecting piece 12, the first diaphragm 31, the fourth connecting piece 14 and the second diaphragm 32, and the other part is combined with the outer peripheral surface of the wound battery cell, and the tail end of the wound battery cell structure is sealed with glue.

[0062] In some embodiments, the widths of the first connecting piece, the second connecting piece, the third connecting piece and the fourth connecting piece are not less than 95% of the width of the electrode piece and not greater than the width of the diaphragm, so as to ensure the connection strength between the first connecting piece, the second connecting piece, the third connecting piece and the fourth connecting piece and the electrode piece and the diaphragm, and at the same time achieve a good covering effect on the head and tail of the electrode piece to reduce powder loss; at the same time, it avoids the widths of the first connecting piece, the second connecting piece, the third connecting piece and the fourth connecting piece being too wide, causing them to protrude beyond the diaphragm, forming side covering, and affecting the performance of the wound battery cell.

[0063] It should be noted that the cathode sheet can be provided with a connecting sheet on the outside or on both sides; similarly, the anode sheet can be provided with a connecting sheet on one side or on both sides. For example, when connecting sheets are provided on both sides of the cathode sheet and the anode sheet, the specific structure can be as follows:

[0064] The first connecting piece 11 includes a first connecting piece A111 and a first connecting piece B112; the first connecting piece A111 and the first connecting piece B112 are respectively located on both sides of the rolled end of the cathode piece 21 and connected to the rolled end of the cathode piece 21; the second connecting piece 12 includes a second connecting piece A121 and a second connecting piece B122; the second connecting piece A121 and the second connecting piece B122 are respectively located on both sides of the tail end of the cathode piece 21 and connected to the tail end of the cathode piece 21; The third connecting piece 13 includes a third connecting piece A131 and a third connecting piece B132; the third connecting piece A131 and the third connecting piece B132 are respectively located on both sides of the rolled end of the anode sheet 22 and connected to the rolled end of the anode sheet 22; the fourth connecting piece 14 includes a fourth connecting piece A141 and a fourth connecting piece B142; the fourth connecting piece A141 and the fourth connecting piece B142 are respectively located on both sides of the tail end of the anode sheet 22 and connected to the tail end of the anode sheet 22;

[0065] The first connecting piece A, the first connecting piece B, the third connecting piece A and the third connecting piece B are aligned at one end away from the rolling end of the cathode piece; the second connecting piece A, the second connecting piece B, the fourth connecting piece A and the fourth connecting piece B are aligned at one end away from the tailing end of the cathode piece.

[0066] In other embodiments, a protective sticker is further provided at the connection between the connecting piece and the electrode piece to improve the bonding strength between the electrode piece and the connecting piece and prevent the connecting piece from falling off; especially the first connecting piece and the third connecting piece connected to the starting end of the winding of the electrode piece, because the first connecting piece and the third connecting piece are the traction ends of the wound battery cell during the winding process, and therefore have higher requirements for bonding strength, so the connection between the connecting piece and the electrode piece can be further strengthened by the protective sticker. Exemplarily, when a protective sticker is provided at the connection between the connecting piece and the electrode piece, the structure of the wound battery cell includes: a first protective sticker is provided at the connection between the first connecting piece and the starting end of the cathode piece, the first protective sticker is partially connected to the first connecting piece and partially connected to the cathode piece; a second protective sticker is connected to the connection between the second connecting piece and the ending end of the cathode piece, so that the second protective sticker is partially connected to the second connecting piece and partially connected to the cathode piece;

[0067] A third protective sticker is provided at the connection between the third connecting piece and the rolled end of the anode sheet, and the third protective sticker is partially connected to the third connecting piece and partially connected to the anode sheet; a fourth protective sticker is connected at the connection between the fourth connecting piece and the tail end of the anode sheet, so that the fourth protective sticker is partially connected to the fourth connecting piece and partially connected to the anode sheet.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application. Industrial Applicability

[0069] In summary, this application provides a new wound cell structure that improves or even eliminates electrode burr and powder loss issues, reduces tension fluctuations and the possibility of wrinkles, and facilitates stable control of the spacing between layers. This results in greater controllability of the inner and outer coil ends of the wound cell structure, resulting in improved performance stability.

Claims

1. A wound battery cell structure, characterized in that: include: A cathode sheet, a first separator, an anode sheet, and a second separator are stacked in sequence; the cathode sheet is shorter than the anode sheet, and the anode sheet is shorter than the first separator and the second separator; The battery cell further comprises a first connecting piece, a second connecting piece, a third connecting piece, and a fourth connecting piece; the first connecting piece and the third connecting piece are connected to the first separator and the second separator at portions close to the rolling end of the wound battery cell structure; and the first connecting piece is connected to the rolling end of the cathode sheet at a portion close to the rolling end of the cathode sheet, and the third connecting piece is connected to the rolling end of the anode sheet at a portion close to the rolling end of the anode sheet; The parts of the second connecting piece and the fourth connecting piece close to the winding end of the wound battery cell structure are combined with the first diaphragm and the second diaphragm; and the part of the second connecting piece close to the tail end of the cathode piece is combined with the tail end of the cathode piece, and the part of the fourth connecting piece close to the tail end of the anode piece is combined with the tail end of the anode piece.

2. The wound battery core structure according to claim 1, characterized in that: The portions of the first connecting piece and the third connecting piece close to the rolling end of the wound cell structure are combined with the first separator and the second separator to form a rolling end joint portion; the portion of the first connecting piece close to the rolling end of the cathode sheet is combined with the rolling end of the cathode sheet to form a first joint portion; the portion of the third connecting piece close to the rolling end of the anode sheet is combined with the rolling end of the anode sheet to form a second joint portion; there is a gap between the rolling end joint portion and the first joint portion and the second joint portion; The parts of the second connecting piece and the fourth connecting piece close to the tail end of the wound battery cell structure are combined with the first diaphragm and the second diaphragm to form a tail end joint; the part of the second connecting piece close to the tail end of the cathode piece is combined with the tail end of the cathode piece to form a third joint; the part of the fourth connecting piece close to the tail end of the anode piece is combined with the tail end of the anode piece to form a fourth joint; there is a gap between the tail end joint and the third joint and the fourth joint.

3. The wound battery core structure according to claim 1 or 2, characterized in that: An end of the first connecting piece away from the cathode piece is flush with the rolled-up end of the first diaphragm, the rolled-up end of the second diaphragm, and an end of the third connecting piece away from the anode piece; The offset between the end of the second connecting piece away from the cathode piece and the tail end of the first diaphragm, the tail end of the second diaphragm, and the end of the fourth connecting piece away from the anode piece does not exceed 10 mm.

4. The wound battery core structure according to any one of claims 1 to 3, characterized in that: The first connecting piece, the second connecting piece, the third connecting piece and the fourth connecting piece are all porous connecting pieces.

5. The wound battery core structure according to claim 4, characterized in that: The porosity of the porous connecting sheet is 15-70%, and the average pore diameter is 10-50 μm.

6. The wound battery core structure according to any one of claims 1 to 5, characterized in that: The materials of the first connecting piece, the second connecting piece, the third connecting piece and the fourth connecting piece are all the same as the diaphragm connecting piece.

7. The wound battery core structure according to any one of claims 2 to 6, characterized in that: The combined length of the first connecting piece and the starting end of the cathode piece is not greater than 1.5 times the circumference of the winding needle used to wind the wound battery cell structure; the combined length of the third connecting piece and the starting end of the anode piece is not greater than 1.5 times the circumference of the winding needle used to wind the wound battery cell structure; and / or the combined length of the second connecting piece and the tail end of the cathode piece is at most 1.5 times the circumference of the outer circle of the battery cell; the combined length of the fourth connecting piece and the tail end of the anode piece is at most 1.5 times the circumference of the outer circle of the battery cell.

8. The wound battery core structure according to claim 7, characterized in that: The length of the third connecting portion is not greater than 1.5 times that of the wound battery core structure; and the length of the fourth connecting portion is not greater than 1.5 times that of the wound battery core structure.

9. The wound battery core structure according to any one of claims 1 to 8, characterized in that: The wound battery core structure is provided with a first straight section and a first corner section from the winding end to the winding end; The first corner section includes a first connecting sheet, a first diaphragm, an anode sheet, and a second diaphragm stacked in sequence; The first straight section includes a first connecting piece, a second diaphragm, a second connecting piece, and a second diaphragm stacked in sequence.

10. The wound battery core structure according to any one of claims 1 to 9, characterized in that: The widths of the first connecting piece, the second connecting piece, the third connecting piece and the fourth connecting piece are not less than 95% of the width of the pole piece and not greater than the width of the diaphragm.

11. The wound battery core structure according to any one of claims 1 to 10, characterized in that: The first connecting piece includes a first connecting piece A and a first connecting piece B; the first connecting piece A and the first connecting piece B are respectively located on both sides of the rolled end of the cathode piece and connected to the rolled end of the cathode piece; and / or The second connecting piece includes a second connecting piece A and a second connecting piece B; the second connecting piece A and the second connecting piece B are respectively located on both sides of the tail end of the cathode piece and connected to the tail end of the cathode piece; and / or The third connecting piece includes a third connecting piece A and a third connecting piece B; the third connecting piece A and the third connecting piece B are respectively located on both sides of the rolling end of the anode piece and connected to the rolling end of the anode piece; and / or The fourth connecting piece includes a fourth connecting piece A and a fourth connecting piece B; the fourth connecting piece A and the fourth connecting piece B are respectively located on both sides of the tail end of the anode piece and connected to the tail end of the anode piece; The first connecting piece A, the first connecting piece B, the third connecting piece A and the third connecting piece B are aligned at one end away from the rolling end of the cathode piece; The second connecting piece A, the second connecting piece B, the fourth connecting piece A and the fourth connecting piece B are aligned at ends away from the tail end of the cathode piece.

12. The wound battery core structure according to any one of claims 1 to 11, characterized in that: A first protective sticker is provided at the connection between the first connecting sheet and the rolled-up end of the cathode sheet, wherein the first protective sticker is partially connected to the first connecting sheet and partially connected to the cathode sheet; a second protective sticker is connected at the connection between the second connecting sheet and the tail end of the cathode sheet, wherein the second protective sticker is partially connected to the second connecting sheet and partially connected to the cathode sheet; A third protective film is provided at the connection between the third connecting sheet and the rolled-up end of the anode sheet, wherein the third protective film is partially connected to the third connecting sheet and partially connected to the anode sheet; A fourth protective film is connected to the connection between the fourth connecting piece and the tail end of the anode piece, so that the fourth protective film is partially connected to the fourth connecting piece and partially connected to the anode piece.

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