High-speed winding process and wound battery cell therefrom

Abstract

Embodiments of the present application relate to the technical field of wound battery cells, and provide a high-speed winding process and a wound battery cell. The winding process comprises the following continuously performed procedures: an electrode sheet connection procedure, a combining procedure, and a winding procedure. The connection procedure comprises: using a first connecting strip to connect the tail of a first cathode sheet segment and the head of a second cathode sheet segment, and using a second connecting strip to connect the tail of a first anode sheet segment and the head of a second anode sheet segment. The combining procedure comprises: combining the first connecting strip, a first separator, the second connecting strip, and a second separator to form a multi-layer structure strip. The winding procedure comprises: winding the multi-layer structure strip to form a battery cell, and cutting at the connection location between the first separator, the first connecting strip, the second separator, and the second connecting strip to start winding a next battery cell. The first connecting strip and the second connecting strip are both porous-structured connecting strips. The winding process provided by the embodiments of the present application enables high-speed winding and improves the performance stability of the prepared wound battery cells.

Description

A high-speed winding process and wound battery cell

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application number 202410169141X, filed with the Patent Office of China on February 6, 2024, entitled “A high-speed winding process and its wound battery cell”; the entire contents of which are incorporated by reference into this application. Technical Field

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

[0004] The current bare cell winding process mainly includes the unwinding of the anode and cathode on both sides, the unwinding of the upper diaphragm and the unwinding of the lower diaphragm. The anode and cathode go through the processes of unwinding, tension control, pole piece length measurement, pole piece deviation correction, pole piece cutting, diaphragm length measurement, diaphragm deviation correction, pole piece and diaphragm film combination, automatic winding, diaphragm cutting, adhesive application, and unloading. However, in this winding process, when the cell winding is completed and the diaphragm is cut, the diaphragm speed needs to be reduced to 0, and the diaphragm can only be cut after the winding needle clamps the diaphragm head. When the next core is rolled up, it is also necessary to slowly accelerate from 0 until the pole piece enters the winding needle. Therefore, the winding speed is slow, and high-speed winding is difficult to achieve. Moreover, when the anode and cathode strips are fed into the winding mechanism, since the heads of the anode and cathode are in a free state, the deviation correction effect is difficult to ensure, which affects the alignment of the pole piece and the diaphragm at the head of the cell.

[0005] To address this issue, a recent approach has been proposed to connect severed electrode sheets with adhesive tape, connecting adjacent, severed electrode segments into a continuous whole. This provides a basis for continuous winding, reduces the need for correcting the electrode and separator alignment, and reduces electrode powder loss. However, during the winding process, it was discovered that bubbles, which are difficult to remove, easily form between the adhesive tape, the electrode, and the separator, significantly impacting battery cell performance, making widespread use difficult.

[0006] Application Contents

[0007] One of the purposes of this application is to provide a new winding process for a battery cell structure that can achieve high-speed winding without affecting the performance of the battery cell.

[0008] Another object of the present application is to provide a wound battery cell. In a first aspect, the present application discloses a high-speed winding process, comprising the following steps performed continuously: a pole piece connection step, a bonding step, and a winding step;

[0009] The connecting step includes: connecting the tail of the first cathode sheet segment and the head of the second cathode sheet segment using a first connecting tape, and connecting the tail of the first anode sheet segment and the head of the second anode sheet segment using a second connecting tape;

[0010] The bonding process includes: bonding the first connecting tape, the first diaphragm, the second connecting tape and the second diaphragm to form a multi-layer structure tape;

[0011] The winding process includes: winding the multi-layer structure tape to form a battery cell, and cutting at the connection between the first separator, the first connecting tape, the second separator and the second connecting tape, and then winding the next battery cell;

[0012] Wherein, the first connecting belt and the second connecting belt are both connecting belts with porous structures.

[0013] Furthermore, in some embodiments of the present application, in the combining process, the moving speeds of the first diaphragm and the second diaphragm are both not less than 600 mm / s.

[0014] Furthermore, in some embodiments of the present application, the porosity of the first connecting belt and the second connecting belt are both 15-70%, and the average pore diameter is both 10-50 μm.

[0015] Furthermore, in some embodiments of the present application, the first connecting belt, the first diaphragm, the second connecting belt, and the second diaphragm are bonded by hot pressing, cold pressing, bonding, or electrostatic bonding; and / or

[0016] The bonding method of the first connecting band to the tail of the first cathode sheet segment and the head of the second cathode sheet segment is selected from bonding, cold pressing bonding or hot pressing bonding; the bonding method of the second connecting band to the tail of the first anode sheet segment and the head of the second anode sheet segment is selected from bonding, cold pressing bonding or hot pressing bonding.

[0017] Furthermore, in some embodiments of the present application, the first connecting band and the second connecting band are both diaphragm connecting bands made of the same material as the diaphragm.

[0018] Furthermore, in some embodiments of the present application, in the bonding process, the first cathode sheet segment and the second cathode sheet segment are not bonded to the first separator; the first anode sheet segment and the second anode sheet segment are not bonded to the second separator.

[0019] Furthermore, in some embodiments of the present application, the width of the first connecting strap and the second connecting strap is not less than 95% of the width of the pole piece and not greater than the width of the diaphragm.

[0020] Furthermore, in some embodiments of the present application,

[0021] The combining step includes: combining the first connecting tape and the first diaphragm to obtain a first multilayer structure, and combining the second connecting tape and the second diaphragm to obtain a second multilayer structure;

[0022] Combine the first diaphragm and the second connecting tape to combine the first multi-layer structure and the second multi-layer structure; the bonding area of ​​the first multi-layer structure and the second multi-layer structure does not exceed the vertical projection area of ​​the bonding area of ​​the first connecting tape and the first diaphragm on the bonding area of ​​the second connecting tape and the second diaphragm.

[0023] Furthermore, in some embodiments of the present application, the first cathode sheet segment and the second cathode sheet segment are both connected to each other by the first connecting tape on both sides of the upper and lower sides thereof, and the first connecting tapes located on both sides of the tail of the first cathode sheet segment and the head of the second cathode sheet segment are combined; and / or

[0024] The second connecting strips are used to connect the tail of the first anode sheet segment and the head of the second anode sheet segment on both the upper and lower sides of the first anode sheet segment and the second anode sheet segment, and are combined with the second connecting strips located on both sides of the tail of the first anode sheet segment and the head of the second anode sheet segment.

[0025] Furthermore, in some embodiments of the present application, a first protective film is connected to the connection between the first connecting tape and the tail of the first cathode sheet segment, so that the first protective film is partially connected to the first connecting tape and partially connected to the first cathode sheet segment;

[0026] A second protective film is connected to the connection between the second connecting strip and the tail of the first anode sheet segment, so that the second protective film is partially connected to the second connecting strip and partially connected to the first anode sheet segment.

[0027] Furthermore, in some embodiments of the present application, the combined length of the first connecting tape and the tail of the first cathode sheet segment does not exceed 1.5 times the circumference of the outer ring of the battery cell winding core.

[0028] The combined length of the first connecting tape and the head of the second cathode sheet segment does not exceed 1.5 times the circumference of the winding needle used to wind the wound battery cell; the combined length of the second connecting tape and the head of the second anode sheet segment does not exceed 1.5 times the circumference of the winding needle used to wind the wound battery cell.

[0029] Furthermore, in some embodiments of the present application, the first connecting belt is combined with the head of the second anode sheet segment, and the length of the combination of the first connecting belt and the second anode sheet segment does not exceed the circumference of the winding needle of the winding structure.

[0030] Furthermore, in some embodiments of the present application, a third protective sticker is connected to the connection between the first connecting belt and the head of the second cathode sheet segment, so that the third protective sticker is partially connected to the first connecting belt and partially connected to the second cathode sheet segment; a fourth protective sticker is connected to the connection between the second connecting belt and the head of the second anode sheet segment, so that the fourth protective sticker is partially connected to the second connecting belt and partially connected to the second anode sheet segment; and / or

[0031] Adhere first protective films to both upper and lower sides of the first cathode sheet segment; adhere second protective films to both upper and lower sides of the second anode sheet segment; and / or

[0032] A first protective film is adhered to the upper and lower sides of the first cathode sheet segment, and a third protective film is adhered to the upper and lower sides of the second cathode sheet segment; a second protective film is adhered to the upper and lower sides of the second anode sheet segment; and a fourth protective film is adhered to the upper and lower sides of the second anode sheet segment.

[0033] Furthermore, in some embodiments of the present application, in the connecting step, the first cathode sheet segment and the second cathode sheet segment are moved at a constant speed, and the tail of the first cathode sheet segment and the head of the second cathode sheet segment are connected by a first connecting belt; the first anode sheet segment and the second anode sheet segment are moved at a constant speed, and the tail of the first anode sheet segment and the head of the second anode sheet segment are connected by a second connecting belt;

[0034] In the combining process, the first connecting belt, the second connecting belt, the first diaphragm and the second diaphragm are all moved at a speed of not less than 600 mm / s;

[0035] In the winding process, the winding speed of the battery core multilayer structure is not less than 600 mm / s.

[0036] Furthermore, in some embodiments of the present application, the first diaphragm and the second diaphragm have uniform speeds in the combining process and the winding process, and the first cathode sheet segment, the second cathode sheet segment, the first anode sheet segment and the second anode sheet segment have uniform speeds in the combining process and the winding process.

[0037] In a second aspect, the present application further provides a wound battery core, which is a core wound by the high-speed winding process described in any one of the first aspects.

[0038] Beneficial effects of this application:

[0039] The present application provides a winding process that can achieve high-speed winding of battery cells. After the electrode is cut, the winding process uses a connecting tape to connect the first electrode segment and the second electrode segment obtained after cutting, and combines the connecting tape with the diaphragm during the process, so that the cut first electrode segment, the second electrode segment and the diaphragm form a whole, which can be pulled and moved synchronously, avoiding speed adjustment and winding feeding adjustment caused by differences in traction force and travel speed between the cut electrode and the diaphragm, and eliminating the need to adjust the speed of the first electrode segment, the second electrode segment and the diaphragm during winding feeding, thereby widening the distance between the first electrode segment and the bottom second electrode segment; at the same time, it also avoids the problem of the head of the second electrode segment hanging in the air after the diaphragm is cut, bending, powder loss, difficulty in alignment and other problems caused by no traction feeding, etc. In addition, the connecting belt used in this application is a porous connecting belt, so that after the connecting belt is connected to the first electrode material segment, the second electrode material segment, and the diaphragm, the bubbles formed therein can be discharged during subsequent winding and battery operation and heating, thereby avoiding the inability to discharge bubbles, which leads to bubbling and stratification between the connecting belt and the electrode, the electrode and the diaphragm, and the connecting belt and the diaphragm, thereby causing a decline in battery performance.

[0040] The high-speed winding process provided in the present application can not only improve the defects of the winding process of the wound battery cell in the prior art, such as slow winding speed, powder loss of the electrode, and bending and wrinkling caused by the hanging electrode, but also realize continuous winding of the diaphragm at a speed of more than 600 mm / s, and no stopping or speed reduction when the wound battery cell is separated; it can also improve the defect of the battery cell performance degradation caused by the use of connecting tape to connect the severed electrode, thereby ensuring the high-speed winding of the wound battery cell and no significant degradation of the battery cell performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] FIG1 is a schematic diagram of a process flow of a high-speed winding process provided by some embodiments of the present application;

[0042] FIG2 is a schematic structural diagram of a connecting strip connecting a first pole piece segment and a second pole piece segment provided by some embodiments of the present application;

[0043] FIG3 is a schematic structural diagram of a connecting strip connecting a first pole piece segment and a second pole piece segment provided by some embodiments of the present application;

[0044] FIG4 is a schematic structural diagram of a connecting strip connecting a first pole piece segment and a second pole piece segment provided by some embodiments of the present application;

[0045] FIG5 is a schematic diagram of the bonding area of ​​a first connecting tape, a first cathode sheet segment, a second cathode sheet segment, a first separator, a second connecting tape, a first anode sheet segment, a second anode sheet segment, and a second separator in a high-speed winding process provided by some embodiments of the present application;

[0046] Among them, 101-cathode sheet unwinding process, 102-anode sheet unwinding process, 103-first connecting tape unwinding process, 104-second connecting tape unwinding process, 200-electrode sheet cutting process, 300-electrode sheet connecting process, 400-bonding process, 401-first area, 402-second area, 403-third area, 404-fourth area, 405-fifth area, 406-sixth area, 500-winding process, 601-first cathode sheet segment, 6011-the tail of the first cathode sheet segment, 6012-the first protective film Protective sticker, 602-second cathode sheet segment, 6021-head of the second cathode sheet segment, 6022-third protective sticker, 603-first anode sheet segment, 6031-tail of the first anode sheet segment, 6032-second protective sticker, 604-second anode sheet segment, 6041-head of the first anode sheet segment, 6042-fourth protective sticker, 605-first connecting belt, 606-second connecting belt, 607-first diaphragm, 608-second diaphragm, 701-electrostatic generator, 800-buffer roller group, 900-correction component. DETAILED DESCRIPTION

[0047] 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.

[0048] 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.

[0049] 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.

[0050] Due to the structural design feature that the positive electrode sheet, negative electrode sheet and separator of the wound battery cell are not aligned at the winding end and the winding end of the battery cell, the positive electrode sheet, negative electrode sheet and separator cannot be unwound or wound synchronously during the winding process of the wound battery cell. It is necessary to adjust the speed of the positive electrode sheet and negative electrode sheet during the winding process to increase the spacing between adjacent bottom positive electrode sheets and negative electrode sheets. This requires stopping and reducing the speed of the winding machine when feeding the material, and increasing the speed to the same as the feeding speed of the separator during the winding process, which has a significant impact on the winding efficiency of the battery cell. In order to improve the winding efficiency of the wound battery cell, those skilled in the art are committed to how to realize whether the winding machine can feed the material without reducing the speed. In response to this, it was proposed to cut the positive and negative electrodes before feeding, and to increase the spacing between adjacent positive and negative electrodes, so as to adjust the length difference between the positive and negative electrodes and the separator before feeding. In addition, in order to achieve the synchronous feeding of the positive, negative and separator electrodes, it was proposed to set adhesive tape between adjacent positive and negative electrodes to drive the positive, negative and separator electrodes to move continuously and synchronously, thereby achieving continuous winding. At the same time, in this process, the adhesive tape is used to connect the positive and separator electrodes, and the negative and separator electrodes, and the heads of the positive and negative electrodes can also be covered to reduce the loss of powder from the positive and negative electrodes.

[0051] However, during the research and development process, the inventors discovered that the electrical performance of wound cells formed by connecting the positive and negative electrodes with adhesive tape degraded, and after a period of use, the performance of the wound cells decreased significantly. To address this, the inventors further explored the reasons for the performance degradation of wound cells and found that, after a period of use, wound cells formed by connecting the positive and negative electrodes with adhesive tape were more prone to bubbling and delamination, with bubbling and delamination most likely occurring at the points where the adhesive tape connects the positive and negative electrodes, and the separator. This significantly limits the widespread use of wound cells formed by winding positive and negative electrodes connected with adhesive tape. Further research by the inventors revealed that when connecting the positive and negative electrodes, and the separators, with adhesive tape, tiny bubbles are likely to form during the winding process. These bubbles are partially expelled during the winding process, but are difficult to expel completely, especially when the positive electrode sheet is connected to the tape, the negative electrode sheet is connected to the tape, and the separator is connected to the tape using adhesive. These bubbles can affect the performance of wound cells, especially during long-term use. Furthermore, the poor ion permeability of the adhesive tape can also affect the performance of wound cells.

[0052] On this basis, the inventors proposed a new high-speed winding process, referring to FIG1 , which includes the following steps performed in succession: a pole piece cutting step 200 , a pole piece connecting step 300 , a bonding step 400 , and a winding step 500 ;

[0053] The electrode sheet cutting process includes: cutting the electrode sheet into adjacent first electrode sheet segments and second electrode sheet segments according to the required length of the electrode sheet in the wound battery cell structure, and increasing the distance between the first electrode sheet segment and the second electrode sheet segment;

[0054] The connecting process includes: connecting the tail of the first pole piece segment and the head of the second pole piece segment using a connecting tape;

[0055] The bonding process includes: bonding the connecting tape to the diaphragm to form a multi-layer structure tape;

[0056] The winding process includes: winding the multi-layer structure strip of the battery core to form a battery core, cutting the separator at the connection point with the connecting strip, and simultaneously winding the next battery core;

[0057] Among them, the connecting tape has a porous structure. The porous structure on the connecting tape makes it easy to discharge tiny bubbles that appear at the connection positions of the connecting tape and the electrode and at the connection positions of the connecting tape and the diaphragm during the winding process, and it is also easy to squeeze out during the use of the wound battery cell, avoiding bubbling and stratification. Moreover, its porous structure can also provide a path for ion penetration, improve the defect of performance degradation of the wound battery cell caused by the connecting tape, and achieve high-speed winding while ensuring that the performance of the wound battery cell does not decline or does not decline significantly, so that the production efficiency of the winding process is high and the quality of the battery cell products is stable and excellent.

[0058] It should be noted that the porous structure of the connecting tape used in this application has an average pore size of micrometers and a relatively uniform distribution of pores. Preferably, the connecting tape has a porosity of 15% to 70% and an average pore size of 10 μm to 50 μm. More preferably, the porosity is 25% to 50% and the average pore size is 15 μm to 30 μm to ensure the strength and ion permeability of the connecting tape.

[0059] Preferably, the porosity and average pore size of the connecting belt are the same as or close to those of the diaphragm.

[0060] More preferably, the connecting tape is a diaphragm connecting tape made of the same material as the diaphragm, and its thickness is the same as or less than that of the diaphragm, thereby reducing the increase in the thickness of the cell structure caused by the connecting tape. In this embodiment, since the connecting tape 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. When the connecting tape is connected to the electrode, or when the connecting tape is connected to the diaphragm, the connecting tape and the diaphragm have the same travel speed or winding speed, and their tension is also the same, which can further reduce the formation of bubbles between the connecting tape and the electrode, and between the connecting tape 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 cell. Moreover, since the connecting tape and the diaphragm are film layers of the same material, the wound cell formed by the winding does not actually introduce film layers of other materials / structures, so the performance of the wound cell formed by the winding will not be affected by the introduction of other materials / structures; in addition, the ion permeability of the wound cell is also minimally affected. At the same time, since the tension of the connecting belt and the diaphragm is the same or very close to the same, the composite structure layer formed by the pole piece, connecting belt and diaphragm can greatly increase the travel speed during the winding process. In the present application, during the bonding process, the travel speed of the diaphragm is not less than 600 mm / s, and the travel speed of the pole piece and connecting belt is also very close to the same as the travel speed of the diaphragm. Preferably, in the present application, the travel speed of the diaphragm during the bonding process can reach 1000 mm / s. More preferably, the travel speed of the diaphragm during the bonding process can reach more than 2000 mm / s, achieving extremely high-speed continuous winding.

[0061] In some embodiments, the connecting tape is hot-pressed, cold-pressed, bonded, or electrostatically bonded to the diaphragm. The connecting tape is bonded to the tail of the first pole piece segment and the head of the second pole piece segment by bonding, cold-pressed, or hot-pressed bonding.

[0062] Preferably, when the material of the connecting tape is the same as that of the diaphragm, the connecting tape and the diaphragm are bonded by hot pressing, cold pressing or electrostatic bonding, and more preferably by hot pressing. According to the principle of like-for-like and the inherent adhesiveness of the material of the diaphragm, the bonding strength of the connecting tape and the diaphragm is better when they are bonded by hot pressing, and there is no need to set up additional equipment or procedures for applying adhesives, which is conducive to further improving the winding speed. Moreover, if an additional adhesive layer is applied to achieve the bonding of the connecting tape to the diaphragm or the electrode, it can usually only achieve good bonding on one side with the electrode or the diaphragm. This is because when both sides of the connecting tape need to be coated with adhesive, both sides of the connecting tape need to be coated with adhesive, which easily causes the adhesive to adhere to the structural member (such as a roller) configured to discharge the connecting tape, which is not conducive to the connecting tape being separated from the structural member for discharging the connecting tape to bond with the electrode or the diaphragm, and is likely to cause the connecting tape to wrinkle and bubble.

[0063] It should also be noted that when the material of the connecting tape is the same as that of the diaphragm, it is also beneficial to the flying cutting of the multi-layer structure of the battery cell formed by the connecting tape, the electrode and the diaphragm at the junction of the connecting tape and the diaphragm, so as to avoid the inconsistency of the hot cutting temperature due to the different materials of the connecting tape and the diaphragm, and the inability to use hot cutting; and even if cold cutting is used, due to the certain difference in the strength required for cold cutting, there will be slight differences in the breaking time and retraction position after the flying cutting position is cut off, which will lead to the two ends of the wound battery cell being unable to be aligned.

[0064] In some embodiments, during the connection process, the first pole piece segment and the second pole piece segment are connected by connecting the tail of the first pole piece segment and the head of the second pole piece segment while the first pole piece segment and the second pole piece segment are moving at a constant speed.

[0065] In the combining process, the speed of the connecting tape and the diaphragm is not less than 600 mm / s; in the winding process, the winding speed of the multi-layer structure of the battery cell formed by the connecting tape, the electrode and the diaphragm is not less than 600 mm / s, preferably not less than 1000 mm / s, and can further reach 2000 mm / s, so that in the winding process, the overall winding speed of the multi-layer structure of the battery cell is not less than 600 mm / s.

[0066] Preferably, by adopting the winding process of the present application, the speed of the connecting tape and the diaphragm in the combining process can be increased to not less than 1000 mm / s, or even to 2000 mm / s; the winding speed of the multi-layer structure of the battery cell formed by the connecting tape, the pole piece and the diaphragm in the winding process can also be simultaneously increased to above 1000 mm / s, or even to above 2000 mm / s, and stable continuous winding can still be achieved.

[0067] In the winding process of the present application, the overall winding speed of the multi-layer structure of the battery cell can reach 2300 mm / s.

[0068] In some embodiments, the diaphragm has a uniform running speed during the combining process and the winding process, and the pole piece has a uniform running speed during the combining process and the winding process.

[0069] It should be noted that the "uniform speed" in the winding process provided in this application should be understood as a speed that is similar or infinitely close to the speed and remains unchanged, and cannot be understood as the speed remaining unchanged in an absolute sense; and the "uniform speed" provided in this application should be understood as the speed of the film layer does not change significantly in a certain process or certain processes; such as "the speed of the diaphragm in the combining process and the winding process is uniform", which should be understood as the speed of the diaphragm in the combining process does not change significantly during the continuous winding process, the speed of the diaphragm in the winding process does not change significantly during the continuous winding process, and the speed of the diaphragm in the combining process and the speed in the winding process are similar or infinitely close to being equal, that is, the speed of the diaphragm remains unchanged from unwinding to winding cutting. “The pole piece has a uniform speed in the combining process and the winding process” should be understood as the speed of the pole piece (cathode piece / anode piece) in the combining process does not change significantly during the continuous winding process, the speed of the pole piece (cathode piece / anode piece) in the winding process does not change significantly during the continuous winding process, and the speed of the pole piece (cathode piece / anode piece) in the combining process is similar to or infinitely approaches the same as the speed in the winding process. In addition, the connecting belt also has a uniform speed in the combining process and the winding process.

[0070] In some embodiments, in the bonding process, the first pole piece segment and the second pole piece segment are not bonded to the diaphragm, and are only bonded to the diaphragm through a connecting tape, so that the pole piece and the diaphragm form a multi-layer structure of the battery cell after the bonding process, so as to maintain the freedom of the first pole piece segment and the second pole piece segment as much as possible, facilitate deviation correction and tension release, and at the same time improve the defect of the pole piece head being suspended due to the pole piece not being connected to the diaphragm and the defect that the pole piece and the diaphragm are difficult to align after being combined into a whole; it also improves the defect that the pole piece is prone to bending and wrinkling due to tension problems.

[0071] In other embodiments, the tail of the first pole piece segment is not connected to the diaphragm; the head of the second pole piece segment is connected to the diaphragm, that is, the tail of the first pole piece segment still maintains its freedom, which is convenient for pole piece correction and tension release; and its head is connected to the diaphragm to enhance the connection strength between the pole piece and the diaphragm and reduce the risk of falling off.

[0072] It should be noted that the length of the "head" provided in this application shall not exceed 1.5 times the circumference of the winding needle used to wind the battery cell, and shall not be less than the circumference of the winding needle used to wind the battery cell. It can be understood that the circumference ≤ the length of the "head" ≤ 1.5 times the circumference. The "tail" refers to the lengthwise portion of the electrode sheet other than the "head".

[0073] In some embodiments, the width of the connecting tape is not less than 95% of the width of the electrode and not greater than the width of the diaphragm, so as to ensure the connection strength between the connecting tape and the electrode and the diaphragm, while achieving a good covering effect on the head and tail of the electrode to reduce powder loss; at the same time, it avoids the width of the connecting tape being too wide, causing it to protrude beyond the diaphragm, forming a side covering, and affecting the performance of the wound battery cell.

[0074] In some embodiments, referring to FIG2 , the electrode sheet includes a cathode sheet and an anode sheet, the first electrode sheet segment includes a first cathode sheet segment 601 and a first anode sheet segment 603; the second electrode sheet segment includes a second cathode sheet segment 602 and a second anode sheet segment 604; the diaphragm includes a first diaphragm 607 and a second diaphragm 608; the connecting belt includes a first connecting belt 605 and a second connecting belt 606;

[0075] The connecting process includes: connecting the tail 6011 of the first cathode sheet segment and the head 6021 of the second cathode sheet segment through the first connecting tape 605; connecting the tail 6031 of the first anode sheet segment and the head 6041 of the second anode sheet segment through the second connecting tape 606;

[0076] The combining step includes combining the first connecting tape 605 and the first diaphragm 607 to obtain a first multi-layer structure, and combining the second connecting tape 606 and the second diaphragm 608 to obtain a second multi-layer structure.

[0077] Combine the first diaphragm and the second connecting tape to combine the first multi-layer structure and the second multi-layer structure; the bonding area of ​​the first multi-layer structure and the second multi-layer structure does not exceed the vertical projection area of ​​the bonding area of ​​the first connecting tape and the first diaphragm on the bonding area of ​​the second connecting tape and the second diaphragm.

[0078] The length of the bonding area between the first connecting band 605 and the first diaphragm 607 is less than the length from the tail of the first cathode sheet segment to the head of the second cathode sheet segment, so that the bonding area does not contact the tail of the first cathode sheet segment and the head of the second cathode sheet segment, affecting its degree of freedom; the length of the bonding area between the second connecting band 606 and the second diaphragm 608 is less than the length from the tail of the first anode sheet segment to the head of the second anode sheet segment, so that the bonding area does not contact the tail of the first anode sheet segment and the head of the second anode sheet segment, affecting its degree of freedom.

[0079] Exemplarily, as shown in Figure 5, the bonding area between the first connecting belt and the tail of the first cathode sheet segment is the first area 401, the bonding area between the first connecting belt and the head of the second cathode sheet segment is the second area 402, and the bonding area between the first connecting belt and the first diaphragm is the third area 403; the bonding area between the second connecting belt and the tail of the first anode sheet segment is the fourth area 404, the bonding area between the second connecting belt and the head of the second anode sheet segment is the fifth area 405, and the bonding area between the second connecting belt and the second diaphragm is the sixth area 406; there is a gap between the first area and the third area, and there is also a gap between the second area and the third area; there is a gap between the fourth area and the sixth area, and there is also a gap between the fifth area and the sixth area.

[0080] It should be noted that the first and second cathode sheet segments are cut and spaced apart by a cutting process prior to the joining process and by a buffer roller assembly disposed prior to the cutting assembly employed in the cutting process. Similarly, the first and second anode sheet segments are also spaced apart by a cutting process prior to the joining process. In this application, the cutting process prior to the joining process is prior art and will not be described in detail herein.

[0081] In addition, the winding process also includes a cathode sheet unwinding process 101 and an anode sheet unwinding process 102 before the cutting process, and also includes a first diaphragm unwinding process and a second diaphragm unwinding process before the bonding process; and also includes a first connecting tape unwinding process 103 and a second connecting tape unwinding process 104 before the bonding process, wherein the cathode sheet unwinding process 101, the anode sheet unwinding process 102, the first diaphragm unwinding process and the second diaphragm unwinding process are prior arts in the art and are not described in detail in this application. The first connecting tape unwinding process 103 and the second connecting tape unwinding process 104 can refer to the cathode sheet unwinding process 101 and / or the anode sheet unwinding process 102, that is, using a reel wound with the first connecting tape and a reel wound with the second connecting tape, controlling the rotation of the reel of the first connecting tape and the reel of the second connecting tape by a motor, unwinding the first connecting tape and the second connecting tape at regular intervals, and pressing them on the corresponding cathode sheet / anode sheet by a pressure roller to achieve the bonding of the first connecting tape with the cathode sheet and the second connecting tape with the anode sheet. The first and second connecting belts may be pre-cut to the required length, or they may be cut to a predetermined length by providing a cutting assembly before combining the pressure rollers used.

[0082] It should be noted that in the present application, the first cathode sheet segment and the second cathode sheet segment may be provided with a first connecting strap on one side or on both sides; similarly, the first anode sheet segment and the second anode sheet segment may be provided with a second connecting strap on one side or on both sides. Preferably, the first connecting strap is provided on both sides of the first cathode sheet segment and the second cathode sheet segment, and the second connecting strap is provided on both sides of the first anode sheet segment and the second anode sheet segment, so as to improve the pulling ability of the first connecting strap and the second connecting strap on the second cathode sheet segment and the second anode sheet segment, and prevent the first connecting strap and the second connecting strap from falling off.

[0083] When the first connecting strips are provided on both sides of the first cathode sheet segment and the second cathode sheet segment, and the second connecting strips are provided on both sides of the first anode sheet segment and the second anode sheet segment, the specific structure is as follows:

[0084] Referring to Figure 2, the first cathode sheet segment 601 and the second cathode sheet segment 602 are connected to the tail 6011 of the first cathode sheet segment and the head 6021 of the second cathode sheet segment on both sides by the first connecting tape 605, and the first connecting tape 605 located on both sides of the tail 6011 of the first cathode sheet segment and the head 6021 of the second cathode sheet segment is combined; the first anode sheet segment 603 and the second anode sheet segment 604 are connected to the tail 6031 of the first anode sheet segment and the head 6041 of the second anode sheet segment on both sides by the second connecting tape 606, and the second connecting tape 606 located on both sides of the tail 6031 of the first anode sheet segment and the head 6041 of the second anode sheet segment is combined.

[0085] In other embodiments, a protective sticker that improves the bonding strength between the connecting strip and the electrode material segment can be further provided at the connection between the connecting strip and the electrode material segment. For example, its specific structure can be: referring to Figures 3 and 4, a first protective sticker 6012 is connected to the connection between the first connecting strip 605 and the tail 6011 of the first cathode material segment, so that the first protective sticker 6012 is partially connected to the first connecting strip 605 and partially connected to the first cathode material segment 601, so as to further enhance the bonding strength between the first connecting strip and the first cathode material segment; a second protective sticker 6032 is connected to the connection between the second connecting strip 606 and the tail 6031 of the first anode material segment, so that the second protective sticker 6032 is partially connected to the second connecting strip 606 and partially connected to the first anode material segment 603, so as to further enhance the bonding strength between the second connecting strip and the first anode material segment.

[0086] For example, the specific structure may also be:

[0087] A third protective sticker 6022 is connected to the connection between the first connecting strip 605 and the head 6021 of the second cathode sheet segment, so that the third protective sticker is partially connected to the first connecting strip and partially connected to the second cathode sheet segment; a fourth protective sticker 6042 is connected to the connection between the second connecting strip 606 and the head 6041 of the second anode sheet segment, so that the fourth protective sticker is partially connected to the second connecting strip and partially connected to the second anode sheet segment; the first protective sticker is adhered to the upper and lower sides of the first cathode sheet segment; the second protective sticker is adhered to the upper and lower sides of the second anode sheet segment; the first protective sticker is adhered to the upper and lower sides of the first cathode sheet segment, and the third protective sticker is adhered to the upper and lower sides of the second cathode sheet segment; the fourth protective sticker is adhered to the upper and lower sides of the second anode sheet segment.

[0088] In some embodiments, the combined length of the first connecting strap and the tail of the first cathode sheet segment does not exceed 1.5 times the outer circumference of the wound cell, thereby integrating the cathode corner separator composite function, ensuring the cell gap voltage difference, and reducing the need for re-applying corner glue. Preferably, the combined length of the first connecting strap and the tail of the first cathode sheet segment does not exceed the outer circumference of the wound cell.

[0089] In some embodiments, the combined length of the first connecting strap and the head of the second cathode sheet segment does not exceed 1.5 times the circumference of the winding needle used to wind the battery cell; the combined length of the second connecting strap and the head of the second anode sheet segment does not exceed 1.5 times the circumference of the winding needle used to wind the battery cell. Preferably, the combined length of the first connecting strap and the head of the second cathode sheet segment is not less than the circumference of the winding needle used to wind the battery cell; and the combined length of the second connecting strap and the head of the second anode sheet segment is not less than the circumference of the winding needle used to wind the battery cell, to prevent the electrode from contacting the winding needle and affecting the battery cell performance.

[0090] In the second aspect, the present application also provides a wound battery cell, which is a wound core obtained by the high-speed winding process described in any one of the first aspects, and the starting end and the ending end of the wound battery cell are both flush at the cut points of the first connecting tape, the second connecting tape, the first diaphragm and the second diaphragm, and the tension of the wound battery cell obtained is controlled to be the same or approximately the same, so that each layer, especially the cathode sheet and / or the anode sheet, is not easy to bend or wrinkle, providing a basis for the stable performance of the wound battery cell. In particular, when the first connecting tape and the second connecting tape are also diaphragms or their materials are the same as those of the diaphragm, the performance of the wound battery cell can be maintained, and because it improves the bending and wrinkling that are easy to occur during the winding process of the electrode sheet, the performance stability of the wound battery cell obtained is even better.

[0091] 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

[0092] In summary, the present application provides a high-speed winding process and a wound battery cell thereof, which can achieve continuous winding with a diaphragm travel speed of more than 600 mm / s, and no stopping or speed reduction when the wound battery cell is separated; it ensures high-speed winding of the wound battery cell and no significant decrease in battery cell performance.

Claims

1. A high-speed winding process, characterized in that: The method comprises the following steps which are carried out continuously: a pole piece connection step, a bonding step and a winding step; The connecting step includes: connecting the tail of the first cathode sheet segment and the head of the second cathode sheet segment using a first connecting tape, and connecting the tail of the first anode sheet segment and the head of the second anode sheet segment using a second connecting tape; The bonding process includes: bonding the first connecting tape, the first diaphragm, the second connecting tape and the second diaphragm to form a multi-layer structure tape; The winding process includes: winding the multi-layer structure tape to form a battery cell, and cutting at the connection between the first separator, the first connecting tape, the second separator and the second connecting tape, and then winding the next battery cell; Wherein, the first connecting belt and the second connecting belt are both connecting belts with porous structures.

2. The high-speed winding process according to claim 1, characterized in that: In the combining process, the moving speeds of the first diaphragm and the second diaphragm are both not less than 600 mm / s.

3. The high-speed winding process according to claim 1 or 2, characterized in that: The porosity of the first connecting belt and the second connecting belt are both 15-70%, and the average pore diameter is both 10-50 μm.

4. The high-speed winding process according to any one of claims 1 to 3, characterized in that: The first connecting tape, the first diaphragm, the second connecting tape, and the second diaphragm are bonded by hot pressing, cold pressing, bonding, or electrostatic bonding; and / or The first connecting strip is bonded to the tail of the first cathode sheet segment and the head of the second cathode sheet segment in a manner selected from bonding, cold pressing or hot pressing; The second connecting belt is bonded to the tail of the first anode sheet segment and the head of the second anode sheet segment in a manner selected from bonding, cold pressing or hot pressing.

5. The high-speed winding process according to any one of claims 1 to 4, characterized in that: The first connecting belt and the second connecting belt are both diaphragm connecting belts made of the same material as the diaphragm.

6. The high-speed winding process according to any one of claims 1 to 5, characterized in that: In the bonding process, the first cathode sheet segment and the second cathode sheet segment are not bonded to the first separator; and the first anode sheet segment and the second anode sheet segment are not bonded to the second separator.

7. The high-speed winding process according to any one of claims 1 to 6, characterized in that: The width of the first connecting strip and the second connecting strip is not less than 95% of the width of the first cathode sheet segment and not greater than the width of the first separator.

8. The high-speed winding process according to any one of claims 1 to 7, characterized in that: The combining step includes: combining the first connecting tape and the first diaphragm to obtain a first multilayer structure, and combining the second connecting tape and the second diaphragm to obtain a second multilayer structure; Combine the first diaphragm and the second connecting tape to combine the first multi-layer structure and the second multi-layer structure; the bonding area of the first multi-layer structure and the second multi-layer structure does not exceed the vertical projection area of the bonding area of the first connecting tape and the first diaphragm on the bonding area of the second connecting tape and the second diaphragm.

9. The high-speed winding process according to claim 8, characterized in that: The first connecting strip is used to connect the tail of the first cathode sheet segment and the head of the second cathode sheet segment on both the upper and lower sides of the first cathode sheet segment and the second cathode sheet segment, and the first connecting strips are combined on both sides of the tail of the first cathode sheet segment and the head of the second cathode sheet segment; and / or The second connecting strips are used to connect the tail of the first anode sheet segment and the head of the second anode sheet segment on both the upper and lower sides of the first anode sheet segment and the second anode sheet segment, and are combined with the second connecting strips located on both sides of the tail of the first anode sheet segment and the head of the second anode sheet segment.

10. The high-speed winding process according to claim 8 or 9, characterized in that: Connecting a first protective film to the connection between the first connecting strip and the tail of the first cathode sheet segment, so that the first protective film is partially connected to the first connecting strip and partially connected to the first cathode sheet segment; A second protective film is connected to the connection between the second connecting strip and the tail of the first anode sheet segment, so that the second protective film is partially connected to the second connecting strip and partially connected to the first anode sheet segment.

11. The high-speed winding process according to any one of claims 1 to 10, characterized in that: The combined length of the first connecting tape and the tail of the first cathode sheet segment does not exceed 1.5 times the circumference of the outer ring of the wound battery cell.

12. The high-speed winding process according to claim 11, characterized in that: The combined length of the first connecting tape and the head of the second cathode sheet segment does not exceed 1.5 times the circumference of the winding needle used to wind the wound battery cell; the combined length of the second connecting tape and the head of the second anode sheet segment does not exceed 1.5 times the circumference of the winding needle used to wind the wound battery cell.

13. The high-speed winding process according to claim 12, characterized in that: A third protective sticker is connected to the connection between the first connecting belt and the head of the second cathode sheet segment, so that the third protective sticker is partially connected to the first connecting belt and partially connected to the second cathode sheet segment; a fourth protective sticker is connected to the connection between the second connecting belt and the head of the second anode sheet segment, so that the fourth protective sticker is partially connected to the second connecting belt and partially connected to the second anode sheet segment; and / or Adhere first protective films to both upper and lower sides of the first cathode sheet segment; adhere second protective films to both upper and lower sides of the second anode sheet segment; and / or A first protective film is adhered to the upper and lower sides of the first cathode sheet segment, and a third protective film is adhered to the upper and lower sides of the second cathode sheet segment; a second protective film is adhered to the upper and lower sides of the second anode sheet segment; and a fourth protective film is adhered to the upper and lower sides of the second anode sheet segment.

14. The high-speed winding process according to any one of claims 1 to 13, characterized in that: In the connecting step, the first cathode sheet segment and the second cathode sheet segment are connected to each other at a tail end and a head end of the second cathode sheet segment by using a first connecting belt while the first cathode sheet segment and the second anode sheet segment are moving at a constant speed; the first anode sheet segment and the second anode sheet segment are connected to each other at a tail end and a head end of the second anode sheet segment by using a second connecting belt while the first cathode sheet segment and the second anode sheet segment are moving at a constant speed; In the combining process, the first connecting belt, the second connecting belt, the first diaphragm and the second diaphragm are all moved at a speed of not less than 600 mm / s; In the winding process, the winding speed of the battery core multilayer structure is not less than 600 mm / s.

15. The high-speed winding process according to claim 14, characterized in that: The first and second diaphragms have uniform running speeds in the combining process and the winding process, and the first cathode sheet segment, the second cathode sheet segment, the first anode sheet segment and the second anode sheet segment have uniform running speeds in the combining process and the winding process.

16. A wound battery core, the wound battery core being a core wound by the high-speed winding process according to any one of claims 1 to 15.

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