Battery and tab die-cutting method

Abstract

A battery, comprising a battery cell. The battery cell comprises an electrode sheet (1) wound into a plurality of turns, and the electrode sheet (1) has a plurality of tabs (11) folded towards the center of an end surface of the battery cell; in the unfolded structure of the electrode sheet (1), from a first side (12) to a second side (13), the widths of the plurality of tabs (11) change in a gradient manner, and the heights of the plurality of tabs (11) change in a gradient manner, wherein the first side (12) and the second side (13) are two opposite sides of the unfolded structure of the electrode sheet (1) in the length direction. Also provided is a die-cutting processing method for the tabs.

Description

Battery and tab die-cutting method

[0001] This application claims priority to Chinese Patent Application No. 202411965811.5, filed on December 30, 2024, entitled "Method for Die-cutting Tabs and Battery", and to Chinese Patent Application No. 202423285452.7, filed on December 30, 2024, entitled "Battery", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of battery manufacturing technology, specifically to a method for die-cutting batteries and tabs. Background Technology

[0003] In battery production, tab forming technology is one of the key steps to ensure battery performance and safety, and its technological advancements directly affect the overall performance of the battery.

[0004] In related technologies, battery tab forming mainly includes two stages: laser die-cutting and flattening. After the tabs are cut to the designed size and shape using laser die-cutting equipment, the tabs are folded inward and flattened onto the end face of the battery cell using mechanical force through a tab flattening device, so as to facilitate subsequent welding.

[0005] However, due to the influence of equipment stability and tooling fixture positioning accuracy, the tabs may fold outward or be flattened unevenly during the flattening process, resulting in the inner ring of the battery end face not being covered by tabs. In this case, when welding the tabs later, it is easy to weld through the separator of the inner ring of the cell, causing poor tab welding or local short circuit of the battery, thereby affecting the battery performance and reducing the yield. Summary of the Invention

[0006] This application provides a method for die-cutting batteries and tabs, which can improve the problem of tabs folding outward, increase the coverage of tabs on the battery end face, improve battery performance, and increase the yield of battery production.

[0007] In a first aspect, embodiments of this application provide a battery, the battery including a cell, the cell including an electrode sheet wound into multiple turns, the electrode sheet having multiple tabs folded toward the center of the end face of the cell;

[0008] In the unfolded structure of the electrode, the width of the plurality of tabs varies in a gradient from the first side to the second side, and the height of the plurality of tabs varies in a gradient, wherein the first side and the second side are two opposite sides of the unfolded structure of the electrode in the length direction.

[0009] Optionally, from the first side to the second side, the gradient change trend of the width of the plurality of tabs is the same as the gradient change trend of the height.

[0010] Optionally, the first side is the starting side of the winding of the electrode, and the second side is the ending side of the winding of the electrode.

[0011] From the first side to the second side, the width of the plurality of electrodes increases in a gradient trend, and the height of the plurality of electrodes also increases in a gradient trend.

[0012] Optionally, among the multiple tabs located on the same ring of electrode plates, at least two tabs are of equal height and width.

[0013] Optionally, the plurality of tabs on the (i+1)th electrode ring partially overlap with the plurality of tabs on the i-th electrode ring, and the overlap length is less than or equal to half the height of the plurality of tabs on the i-th electrode ring, wherein the direction of the overlap length is parallel to the radial direction of the battery; where i is a positive integer.

[0014] Optionally, the overlap length is greater than or equal to one-quarter of the height of the plurality of tabs on the i-th electrode ring, and less than or equal to one-third of the height of the plurality of tabs on the i-th electrode ring.

[0015] .

[0016] Optionally, the electrode in the i-th ring has a first number of tabs, and the electrode in the (i+1)-th ring has a second number of tabs, the first number being less than the second number, and the difference between the second number and the first number being 2 to 3; where i is a positive integer.

[0017] Optionally, the battery cell has a central hole, and the central hole has a first orthographic projection on the end face of the battery cell;

[0018] The electrode is wound around the central hole, and the multiple tabs on the innermost electrode have a second orthographic projection on the end face of the battery cell.

[0019] The second orthographic projection is located outside the first orthographic projection and surrounds the first orthographic projection, with the inner edge of the second orthographic projection at least partially connected to the outer edge of the first orthographic projection.

[0020] Optionally, in the unfolded structure of the electrode, the two sides of each electrode tab are parallel and inclined relative to the height direction of the electrode tab, wherein the two sides of the electrode tab are arranged opposite to each other in the length direction of the unfolded structure of the electrode.

[0021] Optionally, in the unfolded structure of the electrode, there is a gap between two adjacent electrodes, the gap being smaller than the width of the electrodes; or, two adjacent electrodes can be in separable contact.

[0022] Secondly, embodiments of this application provide a tab die-cutting method for processing the tabs of the battery cell described in the first aspect.

[0023] Thirdly, embodiments of this application provide a method for die-cutting electrode tabs, the method comprising:

[0024] Based on the cell parameters of the cell to be processed, the tab width and tab height of each ring of the electrode sheet in the cell to be processed are calculated. The cell parameters include the cell diameter, electrode sheet thickness, separator thickness and total number of tabs. From the inner ring to the outer ring of the cell to be processed, the tab width and tab height of the electrode sheet show a gradient increasing trend.

[0025] Based on the calculated tab width and tab height of each electrode ring, the tabs of the battery cell to be processed are die-cut.

[0026] Optionally, the step of calculating the tab width and tab height of each turn of the electrode in the battery cell to be processed based on the cell parameters includes:

[0027] Based on the cell parameters, determine the radius R of the i-th electrode ring. i And the number of electrodes N i , 1≤i≤t, where t is the total number of turns of the electrode in the cell to be processed, t≥2, and the t-th turn of the electrode is located on the outermost turn of the cell to be processed;

[0028] Based on the radius R of the i-th electrode ring i And the number of electrodes N i The electrode thickness and the diaphragm thickness are used to calculate the tab width W of the i-th electrode ring. i and the height H of the electrode i .

[0029] Optionally, the step is based on the radius R of the i-th electrode. i And the number of electrodes N i The electrode thickness and the diaphragm thickness are used to calculate the tab width W of the i-th electrode ring. i and the height H of the electrode i ,include:

[0030] Based on the radius R of the i-th electrode ring i And the number of electrodes N i Calculate the tab width W of the i-th electrode ring. i ;

[0031] Based on the radius R of the i-th electrode ring i Calculate the tab height H of the i-th electrode by considering at least one of the electrode thickness and the diaphragm thickness.i .

[0032] Optionally, the cell diameter includes the diameter of the center hole of the cell to be processed, and the diaphragm thickness includes the pre-wound diaphragm thickness;

[0033] When i = 1, the radius R of the i-th electrode plate is used as the basis. i And the number of electrodes N i Calculate the tab width W of the i-th electrode ring. i ,include:

[0034] The radius R1 of the first turn of the electrode is determined based on the diameter of the center hole of the battery cell to be processed, the thickness of the pre-wound diaphragm, and the thickness of the electrode sheet.

[0035] Calculate the perimeter C1 of the first ring of electrode plates based on the radius R1 of the first ring of electrode plates;

[0036] The tab width W1 of the first ring of electrode plates is determined based on the circumference C1 of the first ring of electrode plates and the number of tabs N1 of the first ring of electrode plates.

[0037] Optionally, the tab width W1 of the first ring of electrode plates is calculated using the following formula:

[0038] Where R1 is the radius of the first ring of electrode sheets; d is the diameter of the center hole of the cell to be processed; T0 is the electrode sheet thickness; T1 is the thickness of the pre-wound separator; C1 is the circumference of the first ring of electrode sheets; and N1 is the number of tabs in the first ring of electrode sheets.

[0039] Optionally, the membrane thickness includes the thickness of a single membrane layer;

[0040] When i>1, the radius R of the i-th electrode plate is used as the reference. i And the number of electrodes N i Calculate the tab width W of the i-th electrode ring. i ,include:

[0041] Based on the radius R of the (i-1)th electrode ring i-1 The thickness of the single-layer diaphragm and the thickness of the electrode sheet are used to determine the radius R of the i-th electrode ring. i ;

[0042] Based on the radius R of the i-th electrode ring i Calculate the perimeter C of the i-th electrode ring. i ;

[0043] According to the circumference C of the i-th electrode ring i and the number N of the tabs of the i-th electrode plate i Determine the tab width W of the i-th electrode plate.i .

[0044] Optionally, the diaphragm thickness includes the pre-wound diaphragm thickness;

[0045] When i = 1, the radius R of the i-th electrode plate is used as the basis. i Calculate the tab height H of the i-th electrode by considering at least one of the electrode thickness and the diaphragm thickness. i ,include:

[0046] The tab height H1 of the first turn of the electrode is calculated based on the thickness of the pre-wound diaphragm and the thickness of the electrode sheet.

[0047] Optionally, the tab height H1 of the first ring of electrode plates is calculated using the following formula: H1=T0+T1

[0048] Where T0 is the electrode thickness and T1 is the thickness of the pre-wound separator.

[0049] Optionally, the membrane thickness includes the thickness of a single membrane layer;

[0050] When i>1, the radius R of the i-th electrode plate is used as the reference. i Calculate the tab height H of the i-th electrode by considering at least one of the electrode thickness and the diaphragm thickness. i ,include:

[0051] Based on the radius R of the i-th electrode ring i And the height H of the tab of the (i-1)th electrode plate i-1 Calculate the tab height H of the i-th electrode. i ;

[0052] Wherein, the radius R of the i-th electrode ring i The following formula is used for calculation:

[0053] Where d is the diameter of the center hole of the battery cell to be processed; T0 is the electrode thickness; and T1 is the thickness of the pre-wound separator.

[0054] Optionally, when i>1, the tab height H of the i-th electrode is... i The following formula is used for calculation: H i =2T0+2T1+μH i-1

[0055] Where μ is the overlap coefficient, 0 < μ ≤ 1 / 2.

[0056] Fourthly, embodiments of this application provide a battery having a cell, wherein the tabs of the cell are processed using the tab die-cutting method described in the third aspect.

[0057] The beneficial effects of this application are:

[0058] The battery and tab die-cutting method provided in this application designs the width and height of the tabs on the battery electrode sheet to change in a gradient from the first side to the second side. Increasing the tab width equates to lengthening the pre-fold crease, thus increasing the pre-fold strength and making it less prone to reverse folding, thereby ensuring coverage of the inner ring of the battery. Increasing the tab height increases the contact area between the tab and the flattening mold, making it easier to bend the tab in the pre-fold direction during flattening. Furthermore, the increased width and height of the tab also increase the coverage area of ​​the tab on the battery end face. Therefore, the battery and tab die-cutting method provided in this application, by making the width and height of the tabs on the die-cut electrode sheet change in a gradient, effectively improves the problem of tabs folding outward, allowing the tabs to cover the inner ring of the cell end face and increasing the coverage area of ​​the tabs on the cell end face. This reduces the risk of short circuits caused by welding through the separator of the inner ring of the cell during subsequent tab welding. Therefore, the battery and tab die-cutting method provided in this application can improve battery performance and increase the yield rate of battery production. Attached Figure Description

[0059] Figure 1 is a schematic diagram of the electrode unfolding structure of the battery provided in an embodiment of this application;

[0060] Figure 2 is a schematic diagram of the covering structure of the tabs on the end face of the cell in the battery provided in the embodiment of this application;

[0061] Figure 3 is a flowchart of a tab die-cutting method provided in an embodiment of this application;

[0062] Figure 4 is a flowchart of another electrode die-cutting method provided in an embodiment of this application;

[0063] Figure 5 is a flowchart of the calculation of the tab width on the first ring of the electrode sheet provided in the embodiment of this application;

[0064] Figure 6 is a flowchart of the calculation of the tab width on the i-th electrode plate provided in the embodiment of this application, where i>1;

[0065] Figure 7 is a schematic diagram of the die-cutting route of a cutter for the tabs on an electrode sheet according to an embodiment of this application.

[0066] Reference numerals: 1. Electrode; 11. Tab; 111. Side; 12. First side; 13. Second side; 2. Center hole. Detailed Implementation

[0067] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0068] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0069] This application provides a battery comprising a cell, the cell including an electrode 1 wound in multiple turns, the electrode 1 having multiple tabs 11 folded toward the center of the end face of the cell. As shown in FIG1, in the unfolded structure of the electrode 1, the width of the multiple tabs 11 varies in a gradient from the first side 12 to the second side 13, and the height of the multiple tabs 11 also varies in a gradient, wherein the first side 12 and the second side 13 are opposite sides of the unfolded structure of the electrode 1 in the length direction.

[0070] It should be noted that, in the embodiments of this application, "the end face of the cell" is a part of the end face of the battery. For example, the end face of the battery may also include the cross-section of the battery casing (not shown in the figure); the width or height "changes in a gradient" means that the width or height changes gradually in space, and this change is continuous and regular, usually showing a trend of gradual increase or decrease.

[0071] In the battery provided in this application embodiment, the width and height of the tabs 11 on the electrode 1 are designed to change in a gradient from the first side 12 to the second side 13. Increasing the width of the tab 11 is equivalent to lengthening the pre-fold crease of the tab 11, thus increasing the pre-folding strength of the tab 11 and making it less prone to reverse folding, thereby ensuring coverage of the inner ring of the battery. Increasing the height of the tab 11 increases the contact area between the tab 11 and the flattening mold, improving the flattening tolerance when there is a positional deviation between the tab 11 and the flattening mold, making it easier for the tab 11 to bend in the pre-folding direction during flattening. Furthermore, the increased width and height also increase the coverage area of ​​the tab 11 on the end face of the battery cell. Therefore, the battery provided in this application embodiment, by making the width and height of the tabs 11 on the electrode 1 change in a gradient, can effectively improve the problem of the tabs 11 folding outward, allowing the tabs 11 to cover the inner ring of the battery cell surface and increasing the coverage area of ​​the tabs 11 on the end face of the battery cell.

[0072] In some embodiments of this application, as shown in FIG1, from the first side 12 to the second side 13 of the unfolded structure of the electrode 1, the gradient change trend of the width of the plurality of electrode tabs 11 is the same as the gradient change trend of their height. That is, from the first side 12 to the second side 13 of the unfolded structure of the electrode 1, if the width of the plurality of electrode tabs 11 shows a gradually increasing trend, then the height of these electrode tabs 11 also shows a gradually increasing trend; if the width of the plurality of electrode tabs 11 shows a gradually decreasing trend, then the height of these electrode tabs 11 also shows a gradually decreasing trend.

[0073] Generally speaking, when the height of the tab 11 is lower, its bending resistance is stronger and it is less likely to bend in the opposite direction; when the height of the tab 11 is higher, its bending resistance is weaker and it is more likely to bend in the opposite direction. Therefore, in this embodiment, the width of the multiple tabs 11 gradually increases with the increase of height, thus improving the weakening effect of the increase of height on the bending resistance of the tab 11. This allows the higher tabs 11 to still have good bending resistance, so that during the flattening stage of the tabs 11, both the lower and higher tabs 11 can be easily flattened in the pre-folding direction, thus ensuring that the inner ring of the cell end face is also covered by the tabs 11.

[0074] In some embodiments of this application, the first side 12 is the starting side of winding the electrode 1, and the second side 13 is the ending side of winding the electrode 1; from the first side 12 to the second side 13, the width of the plurality of electrode tabs 11 increases in a gradient trend, and the height of the plurality of electrode tabs 11 increases in a gradient trend.

[0075] After the electrode 1 is wound in the manner described above, the first side 12 of the electrode 1 is located in the inner ring, and the second side 13 of the electrode 1 is located in the outer ring. Correspondingly, the tab 11 on the inner ring electrode 1 is lower in height, and the tab 11 on the outer ring electrode 1 is higher in height. Therefore, after the tab 11 on the outer ring electrode 1 is bent inward, it can overlap with the tab 11 on the inner ring, thereby ensuring the coverage area of ​​the tab 11 on the end face of the cell and facilitating the subsequent welding of the tab 11, which in turn helps to improve the battery performance.

[0076] In some embodiments of this application, as shown in FIG1, among the multiple tabs 11 located on the same ring of electrode plates 1, at least two tabs 11 are of equal height and equal width.

[0077] For multiple tabs 11 located on the same ring of electrode sheets 1, at least two of these tabs 11 have the same height and width. This ensures that the tabs 11 covering the cell end face have a relatively uniform circumferential layer thickness, resulting in a relatively flat and regular formation of the tabs 11 on the cell end face, which is beneficial for improving the uniformity of current distribution in the battery. Furthermore, it helps simplify the tab manufacturing process and reduce the technical difficulty and cost during production.

[0078] Optionally, multiple tabs 11 located on the same ring of electrode sheets 1 are of equal height and width. In this way, the stacking thickness of multiple tabs 11 on the end face of the cell can be approximately equal in the radial direction of the battery or gradually change from the inner ring to the outer ring. This ensures that the tabs 11 are formed flat and regular on the end face of the cell, thereby ensuring uniform current distribution of the battery and avoiding uneven current density caused by inconsistent tab heights, thus improving battery performance and safety.

[0079] In some embodiments of this application, as shown in FIG2, a plurality of tabs 11 on the (i+1)th ring electrode 1 partially overlap with a plurality of tabs 11 on the i-th ring electrode 1, and the overlap length is less than or equal to half the height of the plurality of tabs 11 on the i-th ring electrode 1, wherein the direction of the overlap length is parallel to the radial direction of the battery; wherein i is a positive integer.

[0080] By having overlapping portions between multiple tabs 11 on two adjacent electrode rings 1, it is possible to cover more of the cell end face while also enabling current to flow between the tabs 11, which can shorten the electron transmission path, significantly reduce the battery internal resistance and heat generation, and further improve the battery's safety and thermal stability.

[0081] Moreover, since the tabs 11 on the two adjacent rings of electrode plates 1 are partially overlapped, the problem of excessive protrusion of the end face caused by too many overlapping layers of tabs can be avoided, ensuring that the tabs 11 have sufficient welding strength and welding area on the end face of the cell.

[0082] Tests have shown that when the overlap length is less than or equal to half the height of the multiple tabs 11 on the i-th electrode plate 1, the stacking of the tabs 11 on the end face of the cell can ensure that the battery performance, structural stability and tab 11 welding requirements are met.

[0083] Optionally, the overlap length between the multiple tabs 11 on two adjacent rings of electrode plates 1 is greater than or equal to one-quarter of the height of the multiple tabs 11 on the i-th ring of electrode plates 1, and less than or equal to one-third of the height of the multiple tabs 11 on the i-th ring of electrode plates 1. In this way, better battery performance, structural stability, and tab 11 welding effect can be achieved.

[0084] In some embodiments of this application, as shown in FIG2, the i-th electrode plate 1 has a first number of tabs 11, and the (i+1)-th electrode plate 1 has a second number of tabs 11. The first number is less than the second number, and the difference between the second number and the first number is 2 to 3; where i is a positive integer.

[0085] By making the number of tabs 11 on the outer ring electrode 1 greater than the number of tabs 11 on the inner ring electrode 1, and setting the difference in the number of tabs 11 on two adjacent ring electrode 1s to 2 to 3, the coverage area of ​​the tabs 11 on the outer ring electrode 1 on the cell surface can be increased, which is conducive to achieving full coverage of the cell end face. In this way, when welding the tabs 11 later, it is not easy to weld through the diaphragm of the inner ring of the cell and cause a short circuit.

[0086] In some embodiments of this application, as shown in FIG2, the battery has a central hole 2, which has a first orthographic projection on the end face of the cell; the electrode 1 is wound around the central hole 2, and the plurality of tabs 11 on the innermost electrode 1 have a second orthographic projection on the end face of the cell; wherein the second orthographic projection is located outside the first orthographic projection and surrounds the first orthographic projection, and the inner edge of the second orthographic projection is at least partially connected to the outer edge of the first orthographic projection.

[0087] Since the battery cell is formed by winding a separator and electrode 1 on a battery winding machine, a central hole 2 is formed at the position corresponding to the mandrel of the battery winding machine, and the electrode 1 is wound around the central hole 2. In this embodiment, the second orthographic projection of the tab 11 on the innermost electrode 1 on the end face of the cell is distributed around the first orthographic projection of the central hole 2 on the end face of the cell, and the inner edge of the second orthographic projection overlaps with the outer edge of the first orthographic projection. This means that after the tab 11 on the innermost electrode 1 is folded inward and flattened, it can cover the area around the central hole 2. Therefore, the tab 11 covers the inner circle of the end face of the cell, which can avoid a series of defects caused by the absence of tab 11 covering the inner side of the end face of the cell, and improve battery performance.

[0088] In some embodiments of this application, as shown in FIG1, in the unfolded structure of the electrode 1, the two sides 111 of each electrode tab 11 are parallel and inclined relative to the height direction of the electrode tab 11, wherein the two sides 111 of the electrode tab 11 are arranged opposite to each other in the length direction of the unfolded structure of the electrode 1.

[0089] The tab 11 in the battery provided in this application embodiment can be cut into shape by a laser die-cutting machine. When cutting the tab 11, the cutting direction is perpendicular to the height direction of the tab 11, so the side 111 of the formed tab 11 is inclined. Compared with vertical cutting, cutting the tab 11 at an incline can prevent the electrode sheet 1 from turning outward during the flattening process, and can effectively reduce the roller pressure during flattening, thereby preventing the active material from falling off and reducing the generation of metal chips, and preventing the battery from short-circuiting.

[0090] In some embodiments of this application, in the unfolded structure of the electrode 1, there is a gap between two adjacent tabs 11, the gap being smaller than the width of the tab 11. This avoids welding problems caused by overlapping tabs 11, such as burn-through or incomplete soldering. Furthermore, this design helps reduce the internal resistance of the battery, thereby improving the battery's charging and discharging efficiency and safety.

[0091] In other embodiments of this application, as shown in FIG1, a large-area tab 11 can also be cut to form two small-area tabs 11, and these two tabs 11 can be contacted separately. By designing multiple tabs 11, the rate performance of the battery can be increased, the charging and discharging temperature rise can be reduced, and a larger welding space can be provided when welding the tabs 11, reducing the difficulty of connecting tabs of the same polarity.

[0092] This application also provides a method for die-cutting tabs, which is used to process the tabs of the battery cells described in any of the above embodiments.

[0093] The electrode die-cutting method provided in this application allows for the gradual change in width and height of the die-cut electrode, effectively improving the situation where the electrode folds outward after being flattened. This ensures that the electrode covers the inner ring of the cell end face, thus covering the entire end face of the cell. Consequently, during subsequent electrode welding, it is less likely to weld through the separator of the inner ring of the cell, causing a short circuit. This facilitates safe control of battery performance and improves the yield rate of battery production.

[0094] Optionally, the process of the tab die-cutting method may include the tab die-cutting method of the following embodiments, as well as the method flow shown in Figures 3-6.

[0095] This application provides a method for die-cutting tabs, generally applied to batteries with tabs, such as the batteries described in the above embodiments. As shown in Figure 3, the method for die-cutting tabs includes:

[0096] Step 110: Calculate the tab width and tab height of each turn of the electrode sheet in the battery cell to be processed, based on the cell parameters.

[0097] Among them, the cell parameters include cell diameter, electrode thickness, separator thickness and total number of tabs; from the inner ring to the outer ring of the cell to be processed, the tab width and tab height of the electrode sheets show a gradient increasing trend.

[0098] Step 120: Based on the calculated tab width and tab height of each electrode ring, perform die-cutting on the tabs of the battery cell to be processed.

[0099] The tab die-cutting method provided in this application effectively improves the situation where the tabs fold outwards after being flattened by die-cutting tabs with gradually varying widths and heights. This ensures that the entire end face of the battery cell is covered by the tabs, making it less likely to weld through the separator inside the cell and cause a short circuit during subsequent tab welding. Therefore, using the tab die-cutting method provided in this application to process battery tabs can improve battery performance and increase the yield rate of battery production.

[0100] Figure 4 is a flowchart of a tab die-cutting method provided in an embodiment of this application. As shown in Figure 4, this tab die-cutting method is generally applied to batteries with tabs and includes the following steps:

[0101] Step 210: Obtain cell parameters.

[0102] In this embodiment, the cell parameters include cell diameter, electrode thickness, separator thickness, and total number of tabs.

[0103] The cell diameter includes the outer diameter and the inner diameter. The outer diameter can be determined according to the specifications of the cell to be processed. The inner diameter refers to the diameter of the center hole of the cell to be processed. The diameter of the center hole is generally equal to the diameter of the mandrel used to wind the cell on the battery winding machine.

[0104] Electrode thickness refers to the thickness of the electrode sheet containing the die-cut tab. Generally speaking, a battery cell has a positive electrode sheet and a negative electrode sheet, the thickness of which is equal, and the positive electrode sheet has a positive tab and the negative electrode sheet has a negative tab.

[0105] The separator thickness includes the pre-wound separator thickness and the single-layer separator thickness. The pre-wound separator refers to the separator pre-wound onto the mandrel during the lithium battery winding process. The pre-wound separator is used to ensure that the separator does not shift or misalign during subsequent winding. Generally, without considering pre-wound separator deformation, the pre-wound separator thickness is equal to the product of the single-layer separator thickness and the number of pre-wound turns. However, in the actual pre-wound process, the pre-wound separator may deform due to stretching, leading to a reduction in the single-layer separator thickness. Therefore, in this embodiment, the pre-wound separator thickness is treated as a separate parameter.

[0106] Step 220: Determine the radius R of the i-th electrode based on the cell parameters. i And the number of electrodes N i .

[0107] Where 1≤i≤t. t is the total number of turns of the electrode in the cell to be processed, t≥2. In the embodiments of this application, for ease of explanation later, the first turn of the electrode is considered to be the innermost electrode of the cell to be processed, and the t-th turn of the electrode is considered to be the outermost electrode of the cell to be processed.

[0108] Based on the obtained cell parameters, the radius R of each electrode can be calculated. i And the number of tabs N on each circle of electrode plates i Among them, the radius R of each electrode ring i The number of tabs N on each turn of the electrode can be determined based on the inner diameter of the cell, the thickness of the electrode sheet, and the thickness of the separator. i It can be determined based on the cell outer diameter and the total number of tabs in the cell parameters.

[0109] Optionally, on the electrode sheets of the battery cell to be processed, the number of tabs on the outermost electrode sheets is greater than the number of tabs on the innermost electrode sheets, and the difference in the number of tabs between two adjacent electrode sheets is a preset number. For example, the preset number is 2 to 3.

[0110] Therefore, based on the cell's outer diameter, tab thickness, and separator thickness, the total number of turns of the electrode in the cell to be processed can be calculated. Based on the total number of turns of the electrode and the tab count relationship between adjacent turns of the electrode mentioned above, the number of tabs N on each turn of the electrode can be determined. i For example, the number N of tabs on each turn of the electrode can be... i Treat it as an arithmetic sequence, and then calculate the number N of tabs on each turn of the electrode based on the total number of tabs and the total number of turns of the electrode. i Alternatively, the number of tabs on the first loop of the electrode can be determined first based on the total number of tabs and the total number of turns. Then, the number of tabs on the other loops of the electrode can be determined sequentially based on the number of tabs N1 on the first loop of the electrode. The number of tabs on each loop of the electrode can be adjusted adaptively according to actual needs.

[0111] Step 230: Based on the radius R of the i-th electrode plate i And the number of electrodes N i Calculate the tab width W of the i-th electrode ring based on the electrode thickness and diaphragm thickness. i and the height H of the electrode i .

[0112] Among them, the tab width W of the i-th electrode is i It can be determined based on the radius R of the i-th electrode. i And the number of electrodes N i The corresponding calculations yielded the following result: the tab height H of the i-th electrode ring. i It can be determined based on the radius R of the i-th electrode. i The thickness of the electrode and the thickness of the separator are calculated accordingly.

[0113] Below, this application will describe the tab width W of the i-th electrode plate for two cases: i=1 and i>1. i The calculation methods are explained in detail.

[0114] As shown in Figure 5, when i = 1, according to the radius R of the i-th electrode plate... i And the number of electrodes N i Calculate the tab width W of the i-th electrode ring. i ,include:

[0115] Step 310: Determine the radius R1 of the first turn of the electrode based on the diameter of the center hole of the cell to be processed, the thickness of the pre-wound separator, and the thickness of the electrode sheet.

[0116] The first ring of electrodes is the innermost ring, and its radius R1 can be calculated using the following formula:

[0117] Where d is the diameter of the center hole of the battery cell to be processed, i.e., the inner diameter of the battery cell; T0 is the electrode thickness; and T1 is the thickness of the pre-wound separator.

[0118] Step 320: Calculate the perimeter C1 of the first ring of electrodes based on the radius R1 of the first ring of electrodes.

[0119] Specifically, the perimeter C1 of the first electrode ring can be calculated using the following formula: C1=2πR1

[0120] Step 330: Determine the tab width W1 of the first ring of electrodes based on the circumference C1 of the first ring of electrodes and the number of tabs N1 of the first ring of electrodes.

[0121] Generally speaking, the multiple tabs on each coil of electrode are evenly distributed circumferentially on that coil of electrode. The two are separated by a cutting (die-cutting) process, which can reduce the non-uniformity of current density, avoid the risk of local overheating and short circuit, and also help improve the charging and discharging efficiency and life of the battery.

[0122] Therefore, the tab width W1 of the first ring of electrode can be calculated using the following formula: W1=C1 / N1

[0123] Where C1 is the circumference of the first ring of electrodes; N1 is the number of tabs on the first ring of electrodes.

[0124] As shown in Figure 6, when i>1, according to the radius R of the i-th electrode plate... i And the number of electrodes N i Calculate the tab width W of the i-th electrode ring. i ,include:

[0125] Step 410: Based on the radius R of the (i-1)th electrode plate i-1 The radius R of the i-th electrode is determined by the thickness of the single-layer diaphragm and the electrode thickness. i .

[0126] It should be noted that between the i-th and (i-1)-th electrode layers, there are typically two layers of electrodes (one positive and one negative) and two layers of separator. Accordingly, the radius R of the i-th electrode layer can be calculated using the following formula. i :

[0127] Where d is the diameter of the center hole of the battery cell to be processed; T0 is the electrode thickness; and T1 is the thickness of the pre-wound separator.

[0128] Step 420: Based on the radius R of the i-th electrode plate i Calculate the perimeter C of the i-th electrode ring. i .

[0129] The perimeter C of the i-th electrode ring i The calculation method is similar to step 320, and the following formula can be used for calculation: C i =2πR i

[0130] Step 430: Based on the circumference C of the i-th electrode ring i The number of tabs N of the i-th electrode ring i Determine the tab width W of the i-th electrode ring. i .

[0131] As mentioned above, the multiple tabs on each ring of electrodes are typically evenly distributed circumferentially on that ring. Therefore, the tab width W of the i-th ring of electrodes... i The following formula can be used to calculate: W i =C i / N i

[0132] Among them, C i N is the perimeter of the i-th electrode ring; i Let be the number of tabs on the i-th electrode.

[0133] In summary, following the method shown in Figures 5 and 6, the laser die-cutting equipment can achieve die-cutting positioning along the length of the electrode by calculating the width of each tab on each ring of the electrode sheet.

[0134] Below, this application will address the two cases of i=1 and i>1, and discuss the tab height H of the i-th electrode. i The calculation methods are explained in detail.

[0135] When i = 1, according to the radius R of the i-th electrode ring... i Calculate the tab height H of the i-th electrode layer based on at least one of the electrode thickness and diaphragm thickness. iThis includes: calculating the tab height H1 of the first loop of electrode based on the thickness of the pre-wound diaphragm and the electrode thickness.

[0136] The first ring of electrode plates is the innermost ring. The electrode tab height H1 on the first ring of electrode plates can be calculated using the following formula: H1=T0+T1

[0137] Where T0 is the electrode thickness and T1 is the thickness of the pre-wound separator.

[0138] Based on the aforementioned tab height H1, after the tabs on the first ring of electrode sheets are folded inward and flattened, they can cover the area around the center hole of the cell to be processed. This ensures that the tabs cover the inner ring of the cell end face, avoiding a series of defects caused by the lack of tab coverage on the inner ring of the cell end face. It is beneficial to achieve full coverage of the tabs on the battery end face, as well as to improve battery performance and increase the yield of battery production.

[0139] When i>1, according to the radius R of the i-th electrode ring. i Calculate the tab height H of the i-th electrode layer based on at least one of the electrode thickness and diaphragm thickness. i This includes: based on the radius R of the i-th electrode ring. i And the height H of the tab of the (i-1)th electrode plate i-1 Calculate the tab height H of the i-th electrode ring. i .

[0140] Wherein, the radius R of the i-th electrode ring i The thickness can be determined based on the inner diameter of the cell, the thickness of the electrode sheet, and the thickness of the pre-wound separator. The specific calculation method has been explained above and will not be repeated here.

[0141] When calculating the height of the tabs on the outermost electrode ring, the radius of the outermost electrode ring and the height of the tabs on the previous electrode ring are considered. This ensures that the outermost electrode ring, after folding inward, can overlap at least with the tabs of the previous electrode ring. This ensures that the entire end face of the cell is covered by tabs, thus avoiding the problems of short circuits and poor soldering caused by welding through the separator when the innermost electrode ring lacks tabs. It also avoids the problem of black marks on the end face caused by the lack of tab overlap between the innermost and outermost electrode rings after tab formation. This improves the yield rate of battery manufacturing and enhances battery safety performance. Moreover, since the entire end face of the cell is covered by tabs, and the tabs overlap and guide current, the electron transport path is shortened, significantly reducing the battery's internal resistance and heat generation, further improving battery safety and thermal stability.

[0142] In one example, the tab height of the i-th electrode ring can be equal to the radius R of the i-th electrode ring. iIn this way, the tabs on each ring of electrode plates, after being folded inward and flattened, cover the area around the center hole of the cell to be processed, thus ensuring that the tabs fully cover the end face of the cell.

[0143] However, the above-described solution causes significant bulges on the inner ring (near the center hole) of the cell end face due to the stacking of multiple tabs. This may lead to welding problems such as insufficient weld strength and reduced weld area, affecting the battery's overcurrent capacity and safety, and potentially even causing risks such as short circuits and thermal runaway. Furthermore, uneven tab stacking can also affect battery performance and structural stability. Therefore, in some embodiments of this application, it is necessary to control the stacking of tabs on the cell end face, with the tab height H of the i-th ring of the electrode being... i The following formula can be used for calculation: H i =2T0+2T1+μH i-1

[0144] Where μ is the overlap coefficient, 0 < μ ≤ 1 / 2.

[0145] By adopting the above solution, it can be ensured that after the outer ring of tabs is folded inward and flattened, it can overlap with the inner ring of tabs with a small overlap area. Moreover, there is only a very small overlap area or no overlap between the outer ring of tabs and the inner ring of tabs in the axial direction of the cell to be processed. Therefore, excessive protrusion caused by tab overlap on the end face of the cell is avoided, thus ensuring the welding strength and welding area of ​​the tabs on the end face of the cell, and avoiding the impact on battery performance and battery structural stability.

[0146] In this embodiment, testing has shown that when 0 < μ ≤ 1 / 2, the stacking of the tabs on the battery end face can ensure that the battery performance, structural stability, and tab welding requirements are met. The overlap coefficient μ can be determined based on the electrode width and the axial dimensions of the cell to be processed. Generally, within the range of 0 < μ ≤ 1 / 2, when the difference between the electrode width and the axial dimensions of the cell to be processed is large, the overlap coefficient μ can be set relatively large to ensure that the cell meets the axial dimension requirements; when the difference between the electrode width and the axial dimensions of the cell to be processed is small, the overlap coefficient μ can be set relatively small to prevent the tabs on the end face from protruding excessively and exceeding the axial dimension requirements of the cell. Optionally, 1 / 4 ≤ μ ≤ 1 / 3.

[0147] In summary, following the above method and process, the laser die-cutting equipment can achieve die-cutting positioning in the width direction of the electrode sheet by calculating the height of each tab on each ring of electrode sheet.

[0148] In some embodiments of this application, the tabs of the battery cell to be processed are die-cut based on the calculated tab width and tab height of each turn of the electrode sheet, including:

[0149] When die-cutting the tabs according to the calculated tab width and tab height of each circle of electrode sheets, the cutter enters from the tab cutting point of the innermost electrode sheet and exits from the tab cutting point of the outermost electrode sheet; or, the cutter enters from the tab cutting point of the outermost electrode sheet and exits from the tab cutting point of the innermost electrode sheet.

[0150] As shown in Figure 7, since the electrode tabs cut using the electrode tab die-cutting method provided in this application have a gradient change in width and height, when the cutter enters from the electrode tab cutting point of the innermost electrode sheet and cuts out from the electrode tab cutting point of the outermost electrode sheet, or when the cutter enters from the electrode tab cutting point of the outermost electrode sheet and cuts out from the electrode tab cutting point of the innermost electrode sheet, the electrode tabs can be die-cut and formed in one go, and the waste generated is a whole piece instead of scattered pieces, which facilitates the subsequent waste collection and processing.

[0151] Therefore, by using the electrode die-cutting method provided in this application, the electrode is cut into a shape in which the width and height gradually increase from the inner circle to the outer circle. In the subsequent electrode flattening process, the flattening mold can more easily fold and flatten the electrode towards the inside of the end face, thereby improving the coverage of the electrode on the end face of the cell, which is conducive to achieving full end face coverage and improving the performance and production yield of the cell.

[0152] This application also provides a battery having a cell, the tabs of which are processed using the tab die-cutting method described in the above embodiments.

[0153] The battery provided in this application embodiment has a high coverage of tabs on the end face of the cell because the tabs of the cell are processed by the tab die-cutting method described in the above embodiment. As a result, the battery has good performance and a high yield rate.

Claims

A battery includes a cell, the cell including an electrode (1) wound in multiple turns, the electrode (1) having a plurality of tabs (11) folded toward the center of the end face of the cell; In the unfolded structure of the electrode (1), the width of the plurality of tabs (11) varies in a gradient from the first side (12) to the second side (13), and the height of the plurality of tabs (11) varies in a gradient, wherein the first side (12) and the second side (13) are opposite sides of the unfolded structure of the electrode (1) in the length direction. According to claim 1, wherein, From the first side (12) to the second side (13), the gradient change trend of the width of the plurality of tabs (11) is the same as the gradient change trend of the height. The battery according to claim 2, wherein, The first side (12) is the starting side of the winding of the electrode (1), and the second side (13) is the ending side of the winding of the electrode (1); From the first side (12) to the second side (13), the width of the plurality of tabs (11) increases in a gradient trend, and the height of the plurality of tabs (11) increases in a gradient trend. The battery according to any one of claims 1-3, wherein, Among the multiple tabs (11) located on the same circle of the electrode plate (1), at least two of the tabs (11) are of equal height and equal width. The battery according to claim 4, wherein, The plurality of tabs (11) on the (i+1)th electrode plate (1) partially overlap with the plurality of tabs (11) on the i-th electrode plate (1), and the overlap length is less than or equal to half the height of the plurality of tabs (11) on the i-th electrode plate (1), wherein the direction of the overlap length is parallel to the radial direction of the battery. Where i is a positive integer. According to claim 5, wherein, The overlap length is greater than or equal to one-quarter of the height of the plurality of tabs (11) on the i-th electrode plate (1), and less than or equal to one-third of the height of the plurality of tabs (11) on the i-th electrode plate (1). The battery according to claim 4, wherein, The electrode plate (1) of the i-th ring has a first number of electrode tabs (11), and the electrode plate (1) of the (i+1)-th ring has a second number of electrode tabs (11), the first number being less than the second number, and the difference between the second number and the first number being 2 to 3; Where i is a positive integer. According to claim 1, wherein, The battery cell has a central hole (2), and the central hole (2) has a first orthographic projection on the end face of the battery cell; The electrode (1) is wound around the central hole (2), and the multiple tabs (11) on the innermost electrode (1) have a second orthographic projection on the end face of the battery cell; The second orthographic projection is located outside the first orthographic projection and surrounds the first orthographic projection, with the inner edge of the second orthographic projection at least partially connected to the outer edge of the first orthographic projection. According to claim 1, wherein, In the unfolded structure of the electrode (1), the two sides (111) of each electrode tab (11) are parallel and inclined relative to the height direction of the electrode tab (11), wherein the two sides (111) of the electrode tab (11) are arranged opposite to each other in the length direction of the unfolded structure of the electrode (1). According to claim 1, wherein, In the unfolded structure of the electrode (1), there is a gap between two adjacent electrodes (11), the gap being smaller than the width of the electrodes (11); or, two adjacent electrodes (11) can be in separable contact. A method for die-cutting tabs for processing the tabs of the battery cell according to any one of claims 1-10. A method for die-cutting electrode tabs, comprising: Based on the cell parameters of the cell to be processed, the tab width and tab height of each ring of the electrode sheet in the cell to be processed are calculated. The cell parameters include the cell diameter, electrode sheet thickness, separator thickness and total number of tabs. From the inner ring to the outer ring of the cell to be processed, the tab width and tab height of the electrode sheet show a gradient increasing trend. Based on the calculated tab width and tab height of each electrode ring, the tabs of the battery cell to be processed are die-cut. According to claim 12, the electrode die-cutting method, wherein, The step of calculating the tab width and tab height of each turn of the electrode in the battery cell to be processed, based on the cell parameters, includes: Based on the cell parameters, determine the radius R of the i-th electrode ring. i And the number of electrodes N i , 1≤i≤t, where t is the total number of turns of the electrode in the cell to be processed, t≥2, and the t-th turn of the electrode is located on the outermost turn of the cell to be processed; Based on the radius R of the i-th electrode ring i And the number of electrodes N i The electrode thickness and the diaphragm thickness are used to calculate the tab width W of the i-th electrode ring. i and the height H of the pole i . According to claim 13, the electrode die-cutting method, wherein, The radius R of the i-th electrode is used as a reference. i And the number of electrodes N i The electrode thickness and the diaphragm thickness are used to calculate the tab width W of the i-th electrode ring. i and the height H of the pole i ,include: Based on the radius R of the i-th electrode ring i And the number of electrodes N i Calculate the tab width W of the i-th electrode ring. i ; Based on the radius R of the i-th electrode ring i Calculate the tab height H of the i-th electrode by considering at least one of the electrode thickness and the diaphragm thickness. i . According to claim 14, the electrode die-cutting method, wherein, The cell diameter includes the diameter of the center hole of the cell to be processed, and the diaphragm thickness includes the pre-wound diaphragm thickness; When i = 1, the radius R of the i-th electrode plate is used as the basis. i And the number of electrodes N i Calculate the tab width W of the i-th electrode ring. i ,include: The radius R1 of the first turn of the electrode is determined based on the diameter of the center hole of the battery cell to be processed, the thickness of the pre-wound diaphragm, and the thickness of the electrode sheet. Calculate the perimeter C1 of the first ring of electrode plates based on the radius R1 of the first ring of electrode plates; The tab width W1 of the first ring of electrode plates is determined based on the circumference C1 of the first ring of electrode plates and the number of tabs N1 of the first ring of electrode plates. According to the electrode die-cutting method of claim 15, wherein, The tab width W1 of the first ring of electrode plates is calculated using the following formula: Where R1 is the radius of the first ring of electrode sheets; d is the diameter of the center hole of the cell to be processed; T0 is the electrode sheet thickness; T1 is the thickness of the pre-wound separator; C1 is the circumference of the first ring of electrode sheets; and N1 is the number of tabs in the first ring of electrode sheets. The electrode die-cutting method according to any one of claims 14-16, wherein, The diaphragm thickness includes the thickness of a single diaphragm layer; When i>1, the radius R of the i-th electrode plate is used as the reference. i And the number of electrodes N i Calculate the tab width W of the i-th electrode ring. i ,include: Based on the radius R of the (i-1)th electrode ring i-1 The thickness of the single-layer diaphragm and the thickness of the electrode sheet are used to determine the radius R of the i-th electrode ring. i ; Based on the radius R of the i-th electrode ring i Calculate the perimeter C of the i-th electrode ring. i ; According to the circumference C of the i-th electrode ring i and the number N of the tabs of the i-th electrode plate i Determine the tab width W of the i-th electrode ring. i . According to claim 14, the electrode die-cutting method, wherein, The diaphragm thickness includes the pre-wound diaphragm thickness; When i = 1, the radius R of the i-th electrode plate is used as the basis. i Calculate the tab height H of the i-th electrode by considering at least one of the electrode thickness and the diaphragm thickness. i ,include: The tab height H1 of the first turn of the electrode is calculated based on the thickness of the pre-wound diaphragm and the thickness of the electrode sheet. According to claim 18, the electrode die-cutting method, wherein, The tab height H1 of the first ring of electrodes is calculated using the following formula: H1 = T0 + T1 Where T0 is the electrode thickness and T1 is the thickness of the pre-wound separator. The electrode die-cutting method according to claim 18 or 19, wherein, The diaphragm thickness includes the thickness of a single diaphragm layer; When i>1, the radius R of the i-th electrode plate is used as the reference. i Calculate the tab height H of the i-th electrode by considering at least one of the electrode thickness and the diaphragm thickness. i ,include: Based on the radius R of the i-th electrode ring i And the height H of the tab of the (i-1)th electrode plate i-1 Calculate the tab height H of the i-th electrode. i ; Wherein, the radius R of the i-th electrode ring i The following formula is used for calculation: Where d is the diameter of the center hole of the battery cell to be processed; T0 is the electrode thickness; and T1 is the thickness of the pre-wound separator. According to claim 20, the electrode die-cutting method, wherein, When i>1, the tab height H of the i-th electrode is... i The following formula is used for calculation: H i =2T0+2T1+μH i-1 Where μ is the overlap coefficient, 0 < μ ≤ 1 / 2. A battery having a cell, wherein the tabs of the cell are processed by the tab die-cutting method according to any one of claims 12-21.

Images