Manufacturing method of winding type laminated core and battery

Abstract

The invention discloses a manufacturing method of a winding type laminated core and a battery, and the manufacturing method of the winding type laminated core comprises the following steps: respectively treating an initial positive pole piece and an initial negative pole piece in a manner of reserving an empty foil area to obtain a treated positive pole piece and a treated negative pole piece; laminating the treated positive pole piece between the first diaphragm and the second diaphragm, and laminating the treated negative pole piece on the other side of the second diaphragm to form a composite laminated core; and taking the empty foil area as a bending position, and bending the composite laminated core inwards along the other side of the first diaphragm to obtain the winding type laminated core. By adopting the manufacturing method of the winding type laminated core, the production efficiency of the winding type laminated core is improved.

Description

Technical Field

[0001] The present application belongs to the field of battery technology, and in particular relates to a method for manufacturing a wound core stack and a battery. Background Art

[0002] The components of lithium-ion batteries include wound core stacks. A wound core stack is made by stacking multiple individual positive and negative electrode sheets in sequence with a separator. However, this method requires stacking individual positive and negative electrode sheets one by one, which results in a high processing time and low production efficiency. Second, each positive and negative electrode sheet needs to be visually inspected separately, which consumes a lot of quality control resources. Summary of the invention

[0003] The embodiments of the present application provide a method for manufacturing a wound stacked core and a battery. The method for manufacturing a wound stacked core according to the embodiments of the present application can improve the production efficiency of the wound stacked core.

[0004] In a first aspect, an embodiment of the present application provides a method for manufacturing a wound stacked core, the method comprising:

[0005] The initial positive electrode sheet and the initial negative electrode sheet are processed respectively by leaving an empty foil area to obtain a processed positive electrode sheet and a processed negative electrode sheet;

[0006] The treated positive electrode sheet is stacked between the first separator and the second separator, and the treated negative electrode sheet is stacked on the other side of the second separator to form a composite stacked core;

[0007] The empty foil area is used as a bending position, and the composite stacked core is bent inward along the other side of the first diaphragm to obtain a wound stacked core.

[0008] Optionally, the initial positive electrode sheet and the initial negative electrode sheet are processed respectively by leaving an empty foil area to obtain a processed positive electrode sheet and a processed negative electrode sheet, including:

[0009] Performing a powder removal treatment on the initial positive electrode sheet of the fully coated foil in the width direction to obtain a treated positive electrode sheet having a plurality of empty foil areas;

[0010] Performing a powder removal treatment on the initial negative electrode sheet of the fully coated foil in the width direction to obtain a treated negative electrode sheet having a plurality of empty foil areas;

[0011] Among them, the width of the empty foil area of ​​the positive electrode plate after treatment is greater than the width of the empty foil area of ​​the negative electrode plate after treatment.

[0012] Optionally, at the same relative position, the powder cleaning interval of the initial positive electrode sheet is consistent with the powder cleaning interval of the initial negative electrode sheet.

[0013] Optionally, the initial positive electrode sheet and the initial negative electrode sheet are subjected to interval powder cleaning treatment using a powder cleaning interval formed by the same increasing arithmetic sequence.

[0014] Optionally, the treated positive electrode sheet is stacked between the first separator and the second separator, and the treated negative electrode sheet is stacked on the other side of the second separator to form a composite stack core, including:

[0015] stacking the treated positive electrode sheet between the first separator and the second separator;

[0016] The processed negative electrode sheets are stacked on the other side of the second separator, and the empty foil area of ​​each processed negative electrode sheet is aligned with the empty foil area of ​​the processed positive electrode sheet at its opposite position.

[0017] Optionally, the hollow foil area is used as a bending position, and the composite laminated core is bent inwardly along the other side of the first diaphragm to obtain a wound laminated core, comprising:

[0018] Using the empty foil area as a bending position, the composite laminated core is bent inwardly along the other side of the first diaphragm;

[0019] The bent composite laminated core is hot pressed to obtain a wound laminated core.

[0020] Optionally, when the initial positive electrode sheet and the initial negative electrode sheet are subjected to the interval powder cleaning treatment, the tab slots on the initial positive electrode sheet and the initial negative electrode sheet are cleaned respectively;

[0021] The bent composite laminated core is hot pressed to obtain a wound laminated core, including:

[0022] hot pressing the bent composite laminated core;

[0023] The tabs are welded to the tab slots of the hot-pressed composite stacked core to obtain a wound stacked core.

[0024] Optionally, the first separator and the second separator are obtained by folding in half, and after processing, the positive electrode plate is wrapped in the first separator and the second separator.

[0025] In a second aspect, an embodiment of the present application provides a battery, the battery comprising a wound core stack, each winding layer of the wound core stack comprising a first separator, a positive electrode sheet, a second separator and a negative electrode sheet stacked in sequence;

[0026] Empty foil areas are respectively reserved on both sides of the positive electrode sheet and the negative electrode sheet of the same winding layer, and the empty foil areas on different sides are arranged at the bending positions of the same winding layer.

[0027] Optionally, the width of the empty foil area of ​​the positive electrode sheet is greater than the width of the empty foil area of ​​the negative electrode sheet.

[0028] Optionally, the positive electrode sheet and the negative electrode sheet are prepared by fully coating the foil, and the empty foil area is obtained by cleaning the powder.

[0029] The embodiment of the present application processes the initial positive electrode sheet and the initial negative electrode sheet respectively by leaving an empty foil area, so as to obtain a processed positive electrode sheet and a processed negative electrode sheet. Then, the processed positive electrode sheet is stacked between the first diaphragm and the second diaphragm, and the processed negative electrode sheet is stacked on the other side of the second diaphragm to form a composite stacked core, so that the composite stacked core can be obtained after one stacking process, thereby improving the production efficiency of the wound stacked core. Finally, the empty foil area is used as a bending position, and the composite stacked core is bent inward along the other side of the first diaphragm to obtain a wound stacked core. Compared with the prior art, the embodiment of the present application does not need to first produce a plurality of separate positive electrode sheets and negative electrode sheets, nor does it need to cross-stack a single positive electrode sheet and a negative electrode sheet with a diaphragm, thereby reducing the number of times the single positive electrode sheet and the negative electrode sheet are aligned, thereby improving the production efficiency of the wound stacked core. In addition, it also avoids the need to perform an appearance inspection on each single positive electrode sheet and negative electrode sheet one by one, and effectively utilizes quality control resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The technical solution and beneficial effects of the present application will be made apparent by describing in detail the specific implementation methods of the present application in conjunction with the accompanying drawings.

[0031] Figure 1 A schematic diagram of a process for manufacturing a winding type stacked core provided in an embodiment of the present application;

[0032] Figure 2 A schematic diagram of performing an interval powder cleaning process on an initial positive electrode plate in the method provided in an embodiment of the present application;

[0033] Figure 3 A schematic diagram of performing an interval powder cleaning process on an initial negative electrode plate in the method provided in an embodiment of the present application;

[0034] Figure 4 A schematic diagram comparing the empty foil areas of the positive electrode sheet after treatment and the negative electrode sheet after treatment in the method provided in an embodiment of the present application;

[0035] Figure 5 A side view of a composite stacked core formed in the method provided in an embodiment of the present application;

[0036] Figure 6 A schematic diagram of a bent composite laminated core in a method provided in an embodiment of the present application;

[0037] Figure 7 This is a schematic diagram of the structure of the wound core stack in the method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0038] Please refer to the drawings, where the same component symbols represent the same components. The principle of the present application is illustrated by implementing it in an appropriate computing environment. The following description is based on the illustrated specific embodiments of the present application, which should not be considered as limiting other specific embodiments of the present application that are not described in detail herein.

[0039] See also Figure 1 , Figure 1 A schematic diagram of a process flow of a method for manufacturing a wound stacked core provided in an embodiment of the present application. The method for manufacturing a wound stacked core can be applied to batteries. The process flow of the method for manufacturing a wound stacked core can include:

[0040] In 101, the initial positive electrode sheet and the initial negative electrode sheet are processed respectively by leaving an empty foil area to obtain a processed positive electrode sheet and a processed negative electrode sheet.

[0041] Among them, a positive electrode sheet with a larger area can be selected as an initial positive electrode sheet, and a negative electrode sheet with a larger area can be selected as an initial positive electrode sheet. After the initial positive electrode sheet and the initial negative electrode sheet are processed by leaving an empty foil area, the processed positive electrode sheet and the processed negative electrode sheet both include an empty foil area and a non-empty foil area.

[0042] The initial positive electrode sheet and the initial negative electrode sheet are divided into multiple separate positive electrode sheets and negative electrode sheets by leaving empty foil areas. These separate positive electrode sheets are called processed positive electrode sheets, and these separate negative electrode sheets are called processed negative electrode sheets.

[0043] In some embodiments, the initial positive electrode sheet and the initial negative electrode sheet may be produced in a full coating manner.

[0044] For example, the positive electrode slurry is continuously and evenly coated on the front and back sides of the current collector by a coating device (such as a blade coater, a slit extrusion coater, etc.), and then the coated current collector is placed in a drying device (such as an oven) for drying to remove the solvent, and finally a rolling device is used for rolling to adjust the thickness and density of the positive electrode sheet to obtain a positive electrode sheet with a larger area. Then, according to the size requirements of the battery, a slitting device is used to cut the positive electrode sheet with a larger area to cut it into initial positive electrode sheets of appropriate width and length.

[0045] The current collector of the initial positive electrode sheet includes aluminum foil, aluminum alloy foil, carbon-coated foil, etc. The positive electrode slurry includes positive electrode active material, conductive agent, binder, etc.

[0046] For another example, the negative electrode slurry is continuously and evenly coated on the front and back sides of the current collector by a coating device, and then the coated current collector is placed in a drying device for drying to remove the solvent, and finally a rolling device is used for rolling to adjust the thickness and density of the negative electrode sheet to obtain a larger area of ​​the negative electrode sheet. Then, according to the size requirements of the battery, a slitting device is used to slit the larger area of ​​the negative electrode sheet to cut it into initial negative electrode sheets of appropriate width and length.

[0047] The current collector of the initial negative electrode sheet includes copper foil, foam copper, composite copper foil, carbon-coated foil, etc. The negative electrode slurry includes negative electrode active material, conductive agent, binder, etc.

[0048] Exemplarily, the initial negative electrode sheet and the initial positive electrode sheet have the same size. As above, after the positive electrode sheet and the negative electrode sheet with a larger area are produced by continuous coating, the initial positive electrode sheet and the initial negative electrode sheet with uniform size and quality can be obtained by cutting the two. When facing the appearance inspection of the initial positive electrode sheet and the initial negative electrode sheet, it is only necessary to check the initial positive electrode sheet and the initial negative electrode sheet once, which reasonably utilizes the quality supervision resources. And the quality stability of the initial positive electrode sheet and the initial negative electrode sheet is maintained, further improving the performance of the wound core stack made based on the initial positive electrode sheet and the initial negative electrode sheet.

[0049] In some embodiments, the initial positive electrode sheet and the initial negative electrode sheet are processed respectively by leaving an empty foil area to obtain a processed positive electrode sheet and a processed negative electrode sheet, including:

[0050] Performing a powder removal treatment on the initial positive electrode sheet of the fully coated foil in the width direction to obtain a treated positive electrode sheet having a plurality of empty foil areas;

[0051] Performing a powder removal treatment on the initial negative electrode sheet of the fully coated foil in the width direction to obtain a treated negative electrode sheet having a plurality of empty foil areas;

[0052] Among them, the width of the empty foil area of ​​the positive electrode plate after treatment is greater than the width of the empty foil area of ​​the negative electrode plate after treatment.

[0053] In this embodiment, the initial positive electrode sheet and the initial negative electrode sheet of the fully coated foil can be subjected to interval powder cleaning by laser powder cleaning. Specifically, the initial positive electrode sheet and the initial negative electrode sheet can be subjected to interval powder cleaning by a laser powder cleaning machine.

[0054] Here, the initial positive electrode sheet is used to illustrate the method of using a laser powder cleaning machine for intermittent powder cleaning. First, place the initial positive electrode sheet on the workbench of the laser powder cleaning machine, and fix the initial positive electrode sheet by a positioning device. Then set the laser power, laser speed, and powder cleaning times of the laser powder cleaning machine. Then adjust the relative position of the laser and the initial positive electrode sheet on the laser powder cleaning machine. Then start the laser to perform laser scanning and powder cleaning on the front side of the initial positive electrode sheet according to the set parameters, so that the positive electrode slurry at the laser scanning action site is peeled off from the current collector of the initial positive electrode sheet, so that the current collector at the scanning action site is exposed. Then, according to the same steps as the front powder cleaning, start the laser to perform laser powder cleaning on the back side of the initial positive electrode sheet. Among them, the parameters configured for the front powder cleaning of the initial positive electrode sheet can be the same as the parameters configured for the back powder cleaning, or they can be adjusted according to actual needs.

[0055] See also Figure 2 , Figure 2 A schematic diagram of the intermittent powder cleaning treatment of the initial positive electrode plate in the method provided in an embodiment of the present application. Figure 2 The upper position is the initial positive electrode sheet, and the arrows indicate the length and width directions of the initial positive electrode sheet, wherein the length of the initial positive electrode sheet is greater than the width, and the length direction is perpendicular to the width direction. The initial positive electrode sheet is cleaned of powder at intervals of a specific width to obtain a treated positive electrode sheet, wherein the treated positive electrode sheet includes a plurality of empty foil areas and a plurality of non-empty foil areas, and the positions of the empty foil areas and the non-empty foil areas are cross-distributed. Among them, the specific width distance is also called the powder cleaning interval, as shown in the figure, the empty foil area is represented by a blank area, and the non-empty foil area is represented by a filled area. If an empty foil area and an adjacent non-empty foil area are called a positive electrode sheet unit, the distance from the farthest end of the width of the non-empty foil area to the farthest end of the width of the empty foil area in the positive electrode sheet unit is called the powder cleaning interval.

[0056] Figure 2 In the figure, "a" and "b" are used to show the two sides of the empty foil area, and the side "b" of the empty foil area is the same as the width of the initial positive electrode sheet. The side "a" of the empty foil area is smaller than the side "b" of the empty foil area. In this case, the side "a" of the empty foil area can be called the width of the empty foil area, and the side "b" of the empty foil area can be called the length of the empty foil area.

[0057] In addition, the adjacent empty foil areas and non-empty foil areas share the same side, and another side of the positive electrode plate unit that does not belong to the shared side has the same size as the powder cleaning interval.

[0058] When performing interval powder cleaning on the initial positive electrode sheet, the first powder cleaning dividing line can be firstly taken from one boundary of the initial positive electrode sheet to the position of the first powder cleaning interval, and the first powder cleaning dividing line is consistent with the width direction of the initial positive electrode sheet. Then, the first powder cleaning dividing line is taken as the powder cleaning boundary, and another powder cleaning boundary is divided at a position of a preset width inward, and the area surrounded by the two powder cleaning boundaries is cleaned to obtain the first empty foil area, and the area surrounded by the first empty foil area and the first non-empty foil area adjacent to it is called the first positive electrode sheet unit. Then, the first powder cleaning dividing line to the position of the second powder cleaning interval is taken as the second powder cleaning dividing line, and the second powder cleaning dividing line is taken as the powder cleaning boundary, and another powder cleaning boundary of the empty foil area is divided at a position of a preset width inward, and the area surrounded by the two powder cleaning boundaries is cleaned to obtain the second empty foil area. And so on, until the interval powder cleaning operation of the initial positive electrode sheet is completed.

[0059] Accordingly, the initial negative electrode sheet can be processed by performing interval powder cleaning on the initial positive electrode sheet. Figure 3 , Figure 3 A schematic diagram of the intermittent powder cleaning treatment of the initial negative electrode plate in the method provided in an embodiment of the present application. Figure 3 The upper position is the initial negative electrode sheet, and the arrows indicate the length and width directions of the initial negative electrode sheet, wherein the length of the initial negative electrode sheet is greater than the width, and the length direction is perpendicular to the width direction. By performing interval powder cleaning on the initial negative electrode sheet based on the powder cleaning interval, a processed negative electrode sheet can be obtained, and a non-empty foil area of ​​the processed negative electrode sheet and its adjacent empty foil area are called a negative electrode sheet unit. As shown in the figure, the empty foil area is represented by a blank area, and the non-empty foil area is represented by a filled area. Among them, the empty foil area and the non-empty foil area in the negative electrode sheet unit share the same edge, and the other edge of the negative electrode sheet unit is the same as the powder cleaning interval.

[0060] Exemplarily, the short side dimension in the empty foil area is called the width of the empty foil area, the long side dimension in the empty foil area is called the length of the empty foil area, the short side in the non-empty foil area is called the width of the non-empty foil area, and the long side dimension in the non-empty foil area is called the length of the non-empty foil area, and is used in the following embodiments. The length of the empty foil area is the same as the length of the non-empty foil area.

[0061] In some embodiments, the powder cleaning interval of the initial positive electrode sheet and the powder cleaning interval of the initial negative electrode sheet can be the same, that is, both use the same powder cleaning interval for interval powder cleaning. The powder cleaning interval can be determined according to the width of the wound core stack to be manufactured, for example, the powder cleaning interval is consistent with the width of the wound core stack to be manufactured.

[0062] Alternatively, the initial positive electrode sheet and the initial negative electrode sheet can be treated with interval powder cleaning using the same increasing arithmetic sequence to form a powder cleaning interval. For example, the width of the positive electrode sheet unit of the treated positive electrode sheet increases in sequence, and the width difference between two adjacent positive electrode sheet units is the same. For example, the widths of the positive electrode sheet units are 1, 2, 3, 4, and 5, respectively. Similarly, the width of the negative electrode sheet unit of the treated negative electrode sheet increases in sequence. If the positive electrode sheet unit and the negative electrode sheet unit in the same sequence are called the positive electrode sheet unit and the negative electrode sheet unit at the same relative position, then the positive electrode sheet unit and the negative electrode sheet unit at the same relative position have the same area, or the same width, or at the same relative position, the powder cleaning interval of the initial positive electrode sheet is consistent with the powder cleaning interval of the initial negative electrode sheet. The width of any positive electrode sheet unit is smaller than the width of the positive electrode sheet unit in the next sequence, or the width of any negative electrode sheet unit is smaller than the width of the negative electrode sheet unit in the next sequence.

[0063] In this embodiment, by reasonably setting the powder cleaning interval, multiple empty foil areas can be quickly cleaned on the initial positive electrode sheet and the initial negative electrode sheet, so as to divide the initial positive electrode sheet into multiple positive electrode sheet units, and divide the initial negative electrode sheet into multiple negative electrode sheet units, and the adjacent positive electrode sheet units are connected by the current collector, and the adjacent negative electrode sheet units are connected by the current collector, so as to facilitate the subsequent rapid production of the wound core stack. When the initial positive electrode sheet and the initial negative electrode sheet are cleaned according to the same powder cleaning interval, it can be ensured that the area of ​​each powder cleaning is highly consistent, and the physical and chemical properties of the empty foil area are kept relatively stable, avoiding local resistance changes caused by differences in powder cleaning effects at different positions. Ensure that the treated positive electrode sheet and the treated negative electrode sheet are subjected to uniform force during the bending process to avoid undesirable phenomena such as wrinkles or breaks.

[0064] If the initial positive electrode sheet and the initial negative electrode sheet can be treated with interval powder cleaning using the same increasing arithmetic sequence, it can also adapt to the thickness variation of the wound core stack, so that each winding layer of the wound core stack maintains a reasonable flatness, making the overall dimensions of the entire core stack more consistent, and ensuring that each monomer wound core stack in the battery has good compatibility and assembly accuracy. The quality of the wound core stack is improved, and the performance of the battery prepared based on the wound core stack is further improved. Furthermore, in large-scale production of battery modules, wound core stacks of consistent size can be arranged and fixed more conveniently, reducing tolerance accumulation during assembly and improving the overall performance and safety of the battery module. At the same time, precise size control is also conducive to improving production efficiency and reducing production costs.

[0065] In summary, in the solution provided in the embodiment of the present application, the initial positive electrode sheet and the initial negative electrode sheet are cleaned at intervals, so that the surface of the treated positive electrode sheet and the treated negative electrode sheet is cleaner and smoother, and the positive and negative electrode sheets can better fit each other when bent. Furthermore, the close fit of the positive and negative electrode sheets is conducive to improving the transmission efficiency of ions between the positive and negative electrodes. For example, during the charging and discharging process of the battery, lithium ions can migrate more smoothly between the pole sheets, reducing the increase in ion transmission resistance and local polarization caused by poor fitting of the pole sheets, thereby making the electrochemical performance of the entire wound core more consistent. In addition, the close fit between the pole sheets can reduce the probability of micro-short circuits, making the self-discharge of each wound core tend to be the same, and also reducing the self-discharge rate inside the battery, further improving the consistency and reliability of the battery.

[0066] In some embodiments, the width of the empty foil area of ​​the processed positive electrode sheet is greater than the width of the empty foil area of ​​the processed negative electrode sheet.

[0067] If the powder cleaning intervals of the initial positive electrode sheet and the initial negative electrode sheet are the same, the width of the hollow foil area in each positive electrode sheet unit in the treated positive electrode sheet is the same, and the width of the hollow foil area in each negative electrode sheet unit in the treated negative electrode sheet is the same. The width of the hollow foil area in each positive electrode sheet unit is greater than the width of the hollow foil area in each negative electrode sheet unit. Figure 4 , Figure 4 A schematic diagram comparing the empty foil areas of the treated positive electrode sheet and the treated negative electrode sheet in the method provided in an embodiment of the present application. In which, each positive electrode sheet unit has the same area (width) as each negative electrode sheet unit, the area (width) of the empty foil area of ​​the positive electrode sheet unit is greater than the area (width) of the empty foil area of ​​the negative electrode sheet unit, and the area (width) of the non-empty foil area of ​​the positive electrode sheet unit is less than the area (width) of the non-empty foil area of ​​the negative electrode sheet unit.

[0068] If the initial positive electrode sheet and the initial negative electrode sheet adopt the same increasing arithmetic sequence to form the powder cleaning interval, the width of the positive electrode sheet unit in the processed positive electrode sheet increases in sequence, and the width difference of adjacent positive electrode sheet units is the same. The width of the negative electrode sheet unit in the processed negative electrode sheet also increases in sequence, and the width difference of adjacent negative electrode sheet units is the same. In addition, the width difference of adjacent positive electrode sheet units is the same as the width difference of adjacent negative electrode sheet units.

[0069] For the same relative position of the treated positive electrode sheet and the treated negative electrode sheet, the area (width) of the positive electrode sheet unit is the same as that of the negative electrode sheet unit, the area (width) of the empty foil area of ​​the positive electrode sheet unit is greater than the area (width) of the empty foil area of ​​the negative electrode sheet unit, and the area (width) of the non-empty foil area of ​​the positive electrode sheet unit is less than the area (width) of the non-empty foil area of ​​the negative electrode sheet unit. For example, the positive electrode sheet units in the treated positive electrode sheet are sequentially referred to as positive electrode sheet unit A, positive electrode sheet unit B, and positive electrode sheet unit C. The negative electrode sheet units in the treated negative electrode sheet are sequentially referred to as negative electrode sheet unit A, negative electrode sheet unit B, and negative electrode sheet unit C. Among them, the area (width) of the positive electrode sheet unit A = the area (width) of the negative electrode sheet unit A, the area (width) of the positive electrode sheet unit B = the area (width) of the negative electrode sheet unit B, and the area (width) of the positive electrode sheet unit C = the area (width) of the negative electrode sheet unit C. The empty foil area (width) of the positive electrode sheet unit A is greater than the empty foil area (width) of the negative electrode sheet unit A, the empty foil area (width) of the positive electrode sheet unit B is greater than the empty foil area (width) of the negative electrode sheet unit B, and the empty foil area (width) of the positive electrode sheet unit C is greater than the empty foil area (width) of the negative electrode sheet unit C. The non-empty foil area (width) of the positive electrode sheet unit A is less than the non-empty foil area (width) of the negative electrode sheet unit A, the non-empty foil area (width) of the positive electrode sheet unit B is less than the non-empty foil area (width) of the negative electrode sheet unit B, and the non-empty foil area (width) of the positive electrode sheet unit C is less than the non-empty foil area (width) of the negative electrode sheet unit C. The empty foil area (width) of the positive electrode sheet unit A is less than the empty foil area (width) of the positive electrode sheet unit B and less than the empty foil area (width) of the positive electrode sheet unit C. The empty foil area (width) of the negative electrode sheet unit A is less than the empty foil area (width) of the negative electrode sheet unit B and less than the empty foil area (width) of the negative electrode sheet unit C.

[0070] In the embodiment of the present application, the width of the empty foil area of ​​the positive electrode sheet unit at the same relative position is set to be greater than the width of the empty foil area of ​​the negative electrode sheet unit, and the width of the non-empty foil area of ​​the negative electrode sheet unit at the same relative position is set to be greater than the width of the non-empty foil area of ​​the positive electrode sheet unit, so that the negative electrode slurry of the negative electrode sheet unit at the relative position completely wraps the positive electrode slurry of the positive electrode sheet unit. It can ensure that during the battery charging and discharging process, the lithium ions released from the positive electrode can be completely accepted by the negative electrode, reducing the loss of lithium ions, thereby increasing the actual capacity of the battery and also helping to improve the capacity utilization of the battery. At the same time, it can reduce the side reactions of the active material during the cycle process, such as the interface reaction between the positive electrode slurry and the electrolyte, so that the battery can maintain a high capacity retention rate, thereby extending the cycle life of the battery.

[0071] In 102 , the processed positive electrode sheet is stacked between the first separator and the second separator, and the processed negative electrode sheet is stacked on the other side of the second separator to form a composite stacked core.

[0072] See also Figure 5 , Figure 5 A side view of a composite stacked core formed in the method provided in an embodiment of the present application. The current collector of the treated positive electrode sheet and the current collector of the treated negative electrode sheet are not shown in the figure. The composite stacked core is composed of a first diaphragm, a treated positive electrode sheet, a second diaphragm and a treated negative electrode sheet from top to bottom. The lengths of the first diaphragm and the second diaphragm are both greater than the lengths of the treated positive electrode sheet and the lengths of the treated negative electrode sheet.

[0073] Exemplarily, the first separator and the second separator have the same width. The width of the treated positive electrode sheet and the treated negative electrode sheet are the same. Alternatively, the widths of the first separator, the second separator, the treated positive electrode sheet, and the treated negative electrode sheet are all the same.

[0074] The second separator is used to separate the positive electrode sheet and the negative electrode sheet after the stacking. When the composite stack is bent, the first separator is used to separate the other side of the positive electrode sheet and the other side of the negative electrode sheet after the stacking.

[0075] In some embodiments, the treated positive electrode sheet is stacked between the first separator and the second separator, and the treated negative electrode sheet is stacked on the other side of the second separator to form a composite stack core, including:

[0076] stacking the treated positive electrode sheet between the first separator and the second separator;

[0077] The processed negative electrode sheets are stacked on the other side of the second separator, and the empty foil area of ​​each processed negative electrode sheet is aligned with the empty foil area of ​​the processed positive electrode sheet at its opposite position.

[0078] When aligning the treated negative electrode sheet with the treated positive electrode sheet, the empty foil area of ​​the positive electrode sheet unit at the same relative position can be aligned with the center of the empty foil area of ​​the negative electrode sheet unit. In this way, it is convenient to bend the composite stacked core one by one based on the center position of each empty foil area, so that the non-empty foil area of ​​the positive electrode sheet unit in each winding layer of the composite stacked core is aligned with the center of the non-empty foil area of ​​the negative electrode sheet unit, thereby maintaining the flatness of each winding layer and the uniformity of the coating distribution, thereby improving the performance of the wound stacked core.

[0079] In some embodiments, the first separator and the second separator are obtained by folding in half, and after processing, the positive electrode plate is wrapped in the first separator and the second separator.

[0080] Among them, by folding a complete diaphragm in half, it can be divided into a first diaphragm and a second diaphragm at the folded position, and then the first diaphragm is placed in the first diaphragm and the second diaphragm, so that the first diaphragm and the second diaphragm wrap the processed positive electrode sheet, and one end of the processed positive electrode sheet is opposite to the folded position of the first diaphragm and the second diaphragm.

[0081] In this embodiment, the first diaphragm and the second diaphragm are folded in half to wrap the processed positive electrode sheet, thereby fixing the position of the processed positive electrode sheet, making it difficult for the processed positive electrode sheet to shift, and reducing the difficulty of winding when subsequently making a wound core stack.

[0082] In 103, the empty foil area is used as a bending position, and the composite laminated core is bent inward along the other side of the first diaphragm to obtain a wound laminated core.

[0083] Among them, the composite core stack can be bent using a winding machine, a bending fixture or a mold, which can ensure the accuracy and consistency of the bending angle.

[0084] See also Figure 6 , Figure 6 The schematic diagram of the folded composite core in the method provided in the embodiment of the present application is that the center of each empty foil area of ​​the composite core is used as the bending position, and the composite core is folded one by one along the inner side of the first diaphragm in the direction indicated by the arrow in the figure to obtain a wound core.

[0085] See also Figure 7 , Figure 7 A schematic diagram of the structure of the wound core stack in the method provided in the embodiment of the present application. Among them, the partially composite core stack laid layer by layer from the inside to the outside of the wound core stack is also called a winding layer, and each winding layer is sequentially a first diaphragm, a positive electrode sheet unit, a second diaphragm and a negative electrode sheet unit from the inside to the outside, and the two sides of each winding layer are the empty foil areas of the positive electrode sheet unit and the negative electrode sheet unit, and the centers of the empty foil areas of the two are aligned.

[0086] In the embodiment of the present application, the bend of the wound core does not contain a material area, and the bend is mainly a current collector, which makes the mechanical properties of the wound core relatively more stable, can better withstand the deformation stress during the cycle, and reduce the possibility of the pole piece slurry falling off due to stress concentration. In this way, the battery made based on the wound core will not cause uneven electrochemical reactions inside the battery, so that it can effectively participate in normal charge and discharge reactions, and improve the capacity and performance of the battery. Furthermore, avoiding the falling of the pole piece slurry at the bend of the battery can make the electrode potential distribution more uniform, avoid increasing the internal resistance of the battery, and provide a smoother transmission channel and a more uniform electric field distribution for lithium ions, so that the negative electrode can more effectively receive and store lithium ions, reduce the risk of lithium plating in the battery, and further improve the performance stability of the battery during the cycle.

[0087] In addition, the bending position of the wound core stack can form a certain physical matching relationship between the processed positive electrode sheet and the processed negative electrode sheet, the first diaphragm and the second diaphragm, thereby limiting the freedom of movement of the positive electrode sheet to a certain extent and playing a fixing role. The surface of the bending position is relatively smooth but has a certain degree of roughness, thereby increasing the friction between other objects, so that when the composite core stack, the wound core stack, etc. are subjected to external forces during movement, the friction between the bending position and other components can prevent the processed positive electrode sheet from sliding or shifting relative to other components, thereby ensuring the smoothness and uniformity of the transmission path of lithium ions inside the battery, thereby ensuring the synchronization of electrochemical reactions in various regions of the battery during the charging and discharging process, improving the overall performance and capacity consistency of the battery, improving production yield and safety, and thus ensuring the quality of the finished product.

[0088] In some embodiments, the hollow foil area is used as a bending position, and the composite laminated core is bent inward along the other side of the first diaphragm to obtain a wound laminated core, comprising:

[0089] Using the empty foil area as a bending position, the composite laminated core is bent inwardly along the other side of the first diaphragm;

[0090] The bent composite laminated core is hot pressed to obtain a wound laminated core.

[0091] In this embodiment, a hot press can be used to hot press the bent composite core. Before hot pressing, a suitable hot pressing temperature can be set according to the material properties of the composite core and the hot pressing process requirements. The pressure of the hot press is also determined according to the thickness of the composite core, the hardness of the material and the hot pressing effect. Then, the hot press is started to gradually apply pressure to the set value, and hot press for a corresponding hot pressing time. Among them, the hot pressing time can be determined according to the material, size and hot pressing process parameters of the composite core.

[0092] The embodiments of the present application reasonably control the hot pressing time to avoid the hot pressing time being too short, which may cause the pole piece and the diaphragm to not fit fully together, thus affecting the structural stability and performance of the wound core stack. It also avoids the hot pressing time being too long, which may cause excessive compression of the bent composite core stack, thus reducing the capacity and cycle life of the battery. And by hot pressing the bent composite core stack, the contact between the pole pieces can be made closer, the gap can be reduced, the resistance can be reduced, and the energy density and charge and discharge efficiency of the battery can be improved.

[0093] In some embodiments, when the initial positive electrode sheet and the initial negative electrode sheet are subjected to the interval powder cleaning treatment, the tab slots on the initial positive electrode sheet and the initial negative electrode sheet are cleaned respectively;

[0094] The bent composite laminated core is hot pressed to obtain a wound laminated core, including:

[0095] hot pressing the bent composite laminated core;

[0096] The tabs are welded to the tab slots of the hot-pressed composite stacked core to obtain a wound stacked core.

[0097] Among them, the tabs are used to connect the battery to the external circuit, and the welding quality directly affects the performance and safety of the battery. Tabs are welded on both the positive and negative pole pieces of the composite stacked core, and the tabs of the two can be led out on the same side or on the opposite sides.

[0098] For example, the welding methods used in welding the tabs include ultrasonic welding, laser welding, resistance welding, etc. In addition, welding parameters such as welding time, welding power, welding pressure, etc. can also be controlled during welding to ensure the firmness and conductivity of the welding.

[0099] When the initial positive electrode sheet and the initial negative electrode sheet are subjected to interval powder cleaning, the lug slots can also be cleaned from both, and the positions of the lug slots can be set according to actual needs. By cleaning out clear lug slots, it can be ensured that the lugs can be accurately welded to the electrode sheets, improving the firmness and conductivity of the welding. Furthermore, cleaning the lug slots can also remove impurities and oxides in the slots, avoiding the generation of poor welding joints during the welding process, reducing resistance, and improving current transmission efficiency.

[0100] In some embodiments, when producing the initial positive electrode sheet and the initial negative electrode sheet, empty foil areas may be reserved on both sides of the initial positive electrode sheet and the initial negative electrode sheet, that is, the electrode sheet slurry is not coated on the two sheets. Then, the tabs are die-cut out of the two empty foil areas.

[0101] In some embodiments, before hot pressing the bent composite laminated core, the method further comprises:

[0102] The first diaphragm and the second diaphragm are folded over the parts that extend beyond the processed positive electrode sheet and the processed negative electrode sheet in the composite stack, and fixing glue is affixed at the end position.

[0103] As in the above embodiment, the lengths of the first diaphragm and the second diaphragm are both greater than the lengths of the processed positive electrode sheet and the processed negative electrode sheet, and the longer section of the first diaphragm and the second diaphragm is used as a reserved diaphragm. One section of the reserved diaphragm can be folded upward, and the other section can be folded downward, and fixing glue can be affixed to the end position to provide good insulation and fixing effect for the assembly of the battery.

[0104] Based on the method for manufacturing a wound core stack provided in the above embodiment, the present application also provides a battery manufactured by the method. Figure 7The battery of the embodiment of the present application includes at least one wound core, which includes wound layers stacked from the inside to the outside, and each wound layer includes a first separator, a positive electrode sheet, a second separator, and a negative electrode sheet stacked in sequence. Empty foil areas are respectively left on both sides of the positive electrode sheet and the negative electrode sheet of the same wound layer, and the empty foil areas on different sides are placed at the bending position of the same wound layer.

[0105] Each winding layer includes the first diaphragm, the positive electrode sheet unit, the second diaphragm and the negative electrode sheet unit stacked from the inside to the outside in the above method. The positive electrode sheet unit and the negative electrode sheet unit of each winding layer are aligned in center, and the two have the same width. In the same winding layer, the empty foil areas of the positive electrode sheet unit and the negative electrode sheet unit are aligned in center, and the empty foil areas of the two are located at the bending position of the winding layer.

[0106] In some embodiments, the width of the empty foil area of ​​the positive electrode sheet is greater than the width of the empty foil area of ​​the negative electrode sheet. By setting the empty foil area of ​​the positive electrode sheet to be larger than the empty foil area of ​​the negative electrode sheet, the slurry of the negative electrode sheet can be completely wrapped with the slurry of the positive electrode sheet. It can ensure that during the charge and discharge process of the battery, the lithium ions released from the positive electrode can be completely accepted by the negative electrode, reducing the loss of lithium ions, thereby increasing the actual capacity of the battery and also helping to improve the capacity utilization of the battery. At the same time, it can reduce the side reactions of the active material during the cycle process, such as the interface reaction between the positive electrode slurry and the electrolyte, so that the battery can maintain a high capacity retention rate, thereby extending the cycle life of the battery.

[0107] In some embodiments, the positive electrode sheet and the negative electrode sheet are prepared by fully coating the foil, and the empty foil area is obtained by cleaning the powder. The specific method of preparing the negative electrode sheet and the positive electrode sheet and the method of obtaining the empty foil area by cleaning the powder are specifically referred to in the above method, which will not be repeated here.

[0108] In some embodiments, the lengths of the positive electrode sheet and the negative electrode sheet in each winding layer are the same. Accordingly, the width of the non-empty foil area of ​​the positive electrode sheet is also smaller than the width of the non-empty foil area of ​​the negative electrode sheet. The positive electrode sheet in each winding layer is also the positive electrode sheet unit in the above method, and the negative electrode sheet in each winding layer is also the negative electrode sheet unit in the above method. Each positive electrode sheet unit and negative electrode sheet unit includes an empty foil area and a non-empty foil area.

[0109] Moreover, the empty foil area is located at the bending position of the wound core stack, which makes the mechanical properties of the wound core stack relatively more stable, can better withstand the deformation stress during the cycle, and reduce the possibility of the pole piece slurry falling off due to stress concentration.

[0110] Furthermore, the battery made based on the wound core stack will not cause uneven electrochemical reactions inside the battery, so that it can effectively participate in normal charge and discharge reactions, thereby improving the capacity and performance of the battery.

[0111] In another embodiment, the length of the outer winding layer can be set to be greater than the length of the inner winding layer. And the width of the empty foil area of ​​the positive electrode sheet in each winding layer is greater than the width of the empty foil area of ​​the negative electrode sheet. And the width of the empty foil area of ​​the positive electrode sheet and the negative electrode sheet in the outer winding layer in adjacent winding layers is greater than the width of the empty foil area of ​​the positive electrode sheet and the negative electrode sheet in the inner winding layer, and the width difference of the empty foil area in adjacent winding layers is the same. In this way, the thickness variation law of the wound core stack is adapted, so that each winding layer of the wound core stack maintains a reasonable flatness, the outer dimensions of the entire core stack are more consistent, and the good compatibility and assembly accuracy between the individual wound core stacks in the battery are ensured.

[0112] In some embodiments, the wound core stack is further provided with a tab. Specifically, both the positive electrode sheet and the negative electrode sheet of the wound core stack are provided with a tab, and the tabs of the positive electrode sheet and the negative electrode sheet can be provided on the same side or on different sides.

[0113] In some embodiments, the first separator and the second separator of the innermost winding layer of the wound core stack are connected.

[0114] It can be understood that the battery provided in the embodiment of the present application may have a group of wound cores made by the method for making wound cores as provided in the above embodiment, or may have multiple groups of such wound cores. The battery assembled by the above-mentioned wound cores allows lithium ions to migrate more smoothly between the pole pieces during the battery charging and discharging process, which can improve the transmission efficiency of ions between the positive and negative electrodes. Furthermore, the lithium ions released from the positive electrode can be fully accepted by the negative electrode, reducing the loss of lithium ions, thereby increasing the actual capacity of the battery, and also helping to improve the capacity utilization of the battery, and reducing the risk of lithium precipitation in the battery, further improving the performance stability of the battery during the cycle. At the same time, the side reactions of the active substance during the cycle can be reduced, so that the battery can maintain a high capacity retention rate, thereby extending the cycle life of the battery.

[0115] Compared with the prior art, the present application does not need to first produce a plurality of separate positive and negative electrode sheets, nor does it need to cross-stack the individual positive and negative electrode sheets with the diaphragm, reducing the number of times the individual positive and negative electrode sheets are aligned, thereby improving the production efficiency of the wound core stack. In addition, it also avoids the need to perform appearance inspections on each individual positive and negative electrode sheet one by one, effectively utilizing quality control resources. Furthermore, the present application performs a uniform interval powder cleaning treatment on the initial positive electrode sheet and the initial negative electrode sheet, thereby ensuring the uniformity of slurry distribution and force uniformity of each winding layer in the wound core stack, and can quickly obtain the treated positive electrode sheet and the treated negative electrode sheet through powder cleaning, which is convenient for preparing the wound core stack based on the winding method, and improves the production efficiency of the wound core stack. It also ensures that the electrochemical reactions of each region of the winding layers of the battery are synchronized during the charging and discharging process, improves the overall performance and capacity consistency of the battery, improves the production yield and safety, and thus ensures the quality of the finished product.

[0116] The battery provided in the embodiment of the present application and the method for manufacturing the wound stacked core in the above embodiment belong to the same concept, and both can achieve the same beneficial effects. The specific implementation process is detailed in the embodiment of the method for manufacturing the wound stacked core, which will not be repeated here.

[0117] The above is a detailed introduction to the method for manufacturing the wound stacked core and the battery provided in the embodiments of the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea; at the same time, for technical personnel in this field, according to the ideas of the present application, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A battery, characterized in that: The battery comprises a wound core stack, each winding layer of the wound core stack comprises a first separator, a positive electrode sheet, a second separator and a negative electrode sheet stacked in sequence; Empty foil areas are respectively reserved on both sides of the positive electrode sheet and the negative electrode sheet of the same winding layer, and the empty foil areas on different sides are arranged at the bending positions of the same winding layer.

2. The battery according to claim 1, characterized in that The width of the empty foil area of ​​the positive electrode plate is greater than the width of the empty foil area of ​​the negative electrode plate.

3. The battery according to claim 1 or 2, characterized in that: The positive electrode sheet and the negative electrode sheet are prepared by fully coating the foil, and the empty foil area is obtained by cleaning the powder.

4. A method for making a winding type stacked core, characterized in that: The method comprises: The initial positive electrode sheet and the initial negative electrode sheet are processed respectively by leaving an empty foil area to obtain a processed positive electrode sheet and a processed negative electrode sheet; The treated positive electrode sheet is stacked between the first separator and the second separator, and the treated negative electrode sheet is stacked on the other side of the second separator to form a composite stacked core; The empty foil area is used as a bending position, and the composite stacked core is bent inwardly along the other side of the first diaphragm to obtain the wound stacked core.

5. The method for manufacturing a wound stacked core according to claim 4, characterized in that: The method of treating the initial positive electrode sheet and the initial negative electrode sheet respectively by leaving an empty foil area to obtain a treated positive electrode sheet and a treated negative electrode sheet comprises: Performing a powder removal treatment on the initial positive electrode sheet of the fully coated foil material in an interval manner along the width direction to obtain the treated positive electrode sheet having a plurality of empty foil areas; Performing a powder removal treatment on the initial negative electrode sheet of the fully coated foil material in an interval manner along the width direction to obtain the treated negative electrode sheet having a plurality of empty foil areas; Wherein, the width of the empty foil area of ​​the treated positive electrode sheet is greater than the width of the empty foil area of ​​the treated negative electrode sheet.

6. The method for manufacturing a wound stacked core according to claim 5, characterized in that: At the same relative position, the powder cleaning interval of the initial positive electrode sheet is consistent with the powder cleaning interval of the initial negative electrode sheet.

7. The method for manufacturing a wound stacked core according to claim 5, characterized in that: The initial positive electrode sheet and the initial negative electrode sheet are subjected to interval powder cleaning treatment using a powder cleaning interval formed by the same increasing arithmetic sequence.

8. The method for manufacturing a wound stacked core according to claim 4, characterized in that: The method comprises stacking the treated positive electrode sheet between the first separator and the second separator, and stacking the treated negative electrode sheet on the other side of the second separator to form a composite stack core, including: stacking the treated positive electrode sheet between the first separator and the second separator; The processed negative electrode sheets are stacked on the other side of the second separator, and the empty foil area of ​​each processed negative electrode sheet is aligned with the empty foil area of ​​the processed positive electrode sheet at its opposite position.

9. The method for manufacturing a wound stacked core according to claim 4, characterized in that: The method of using the empty foil area as a bending position and bending the composite stacked core inwardly along the other side of the first diaphragm to obtain the wound stacked core comprises: Using the empty foil area as a bending position, bending the composite laminated core inwardly along the other side of the first diaphragm; The bent composite laminated core is hot pressed to obtain the wound laminated core.

10. The method for manufacturing a wound stacked core according to claim 9, characterized in that: When the initial positive electrode sheet and the initial negative electrode sheet are subjected to the powder cleaning treatment, the tab slots on the initial positive electrode sheet and the initial negative electrode sheet are cleaned respectively; The step of hot pressing the bent composite stacked core to obtain the wound stacked core comprises: hot pressing the bent composite laminated core; The tabs are welded to the tab slots of the hot-pressed composite stacked core to obtain the wound stacked core.

11. The method for manufacturing a wound stacked core according to any one of claims 4 to 10, characterized in that: The first diaphragm and the second diaphragm are obtained by folding in half, and the processed positive electrode sheet is wrapped in the first diaphragm and the second diaphragm.

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