Multi-electrode pole piece, wound battery preparation process and wound battery

Abstract

The present disclosure provides a multi-electrode tab pole piece, a wound battery preparation process, and a wound battery, relating to the field of battery manufacturing technology. The multi-electrode tab pole piece includes an active material layer and a blank layer, the blank layer includes a flattening layer and a die-cutting layer connected to each other, the flattening layer is arranged on one side of the active material layer, and the die-cutting layer is arranged on the side of the flattening layer away from the active material layer; the die-cutting layer includes a tab-free area in the middle and tab areas on both sides; the tab area of ​​the die-cutting layer is provided with a plurality of slitting grooves, which divide the die-cutting layer into a plurality of tabs, and the depth of the slitting grooves is less than or equal to the height of the die-cutting layer. This can prevent the multi-electrode tab pole piece from folding outwards and warping, or from inserting inwards and piercing the diaphragm during the winding process.

Description

Technical Field

[0001] The present invention relates to the technical field of battery manufacturing, and in particular to a multi-electrode pole piece, a wound battery preparation process and a wound battery. Background Art

[0002] Large cylindrical battery cells are widely used due to their high energy density and strong current handling capacity. Large cylindrical battery cells are mostly processed using a winding process. The incoming material for large cylindrical windings is a positive and negative electrode sheet with all tabs retained. After the electrode assembly is wound, the exposed tabs at both ends need to be flattened to prepare for subsequent assembly processes such as collector plate welding.

[0003] However, during the flattening process, the tabs at both ends of the battery cell are prone to splashing metal debris, affecting battery performance. In severe cases, the tabs are easily squeezed and punctured through the diaphragm during the flattening process, posing a huge safety risk. Summary of the Invention

[0004] The objectives of the present invention include, for example, providing a multi-tab pole piece, a wound battery preparation process and a wound battery, which can avoid the risk of generating a large amount of metal debris and piercing the diaphragm during the flattening and extrusion process of the tab, thereby improving the product qualification rate and improving the performance of the battery product.

[0005] The embodiments of the present invention can be implemented as follows:

[0006] In a first aspect, the present invention provides a multi-tab pole piece, comprising:

[0007] active material layer;

[0008] A blank layer, the blank layer comprising a flattening layer and a die-cutting layer connected to each other, the flattening layer being arranged on one side of the active material layer, and the die-cutting layer being arranged on a side of the flattening layer away from the active material layer; the die-cutting layer comprising a tab-free region in the middle and tab regions on both sides;

[0009] The tab region of the die-cut layer is provided with a plurality of slitting grooves, which divide the die-cut layer into a plurality of tabs. The depth of the slitting grooves is less than or equal to the height of the die-cut layer.

[0010] In an optional embodiment, the cross-sectional shape of the tab is trapezoidal, rectangular, triangular, semicircular, arched, or parallelogram.

[0011] In an optional embodiment, each of the tabs includes a first end connected to the flattening layer and a second end away from the flattening layer, and the sum of the length of the first end and the length of the second end is less than or equal to the sum of the height of the flattening layer and the height of the tab.

[0012] In an optional embodiment, the height of the flattened layer is 0.5 to 2.0 mm, and the height of the tab is 4 to 9 mm.

[0013] In an optional embodiment, the length L of the tab-free area satisfies the following relationship: L=(YXZ)*5*π; wherein X represents the inner diameter of the winding core formed by winding the multi-tab pole pieces, Y represents the outer diameter of the winding core formed by winding the multi-tab pole pieces, and Z represents the height of the tab; π is pi.

[0014] In a second aspect, the present invention provides a process for preparing a wound battery, wherein the wound battery includes the multi-pole tab electrode sheet according to any one of the aforementioned embodiments, wherein the multi-pole tab electrode sheet includes a multi-pole tab positive electrode sheet and a multi-pole tab negative electrode sheet; the wound battery preparation process comprises:

[0015] stacking a separator, the multi-electrode positive electrode sheet, the separator, and the multi-electrode negative electrode sheet in sequence;

[0016] The stacked separator, the multi-tab positive electrode sheet, the separator, and the multi-tab negative electrode sheet are wound to form a winding core; wherein the tabs on the multi-tab positive electrode sheet and the tabs on the multi-tab negative electrode sheet are respectively located at two ends of the winding core;

[0017] pre-pressing the tab;

[0018] Flatten the pre-pressed tab to a preset height.

[0019] In an optional embodiment, the step of pre-pressing the tab includes:

[0020] The tabs on the inner circle and the tabs on the outer circle of the winding core are pre-pressed respectively.

[0021] In an optional embodiment, the bending angle of the tabs of the inner ring during pre-stressing is 120 to 165 degrees, and the bending angle of the tabs of the outer ring during pre-stressing is 30 to 60 degrees.

[0022] In a third aspect, the present invention provides a wound battery, comprising the multi-electrode tab pole piece as described in any one of the aforementioned embodiments, or manufactured using the wound battery preparation process as described in any one of the aforementioned embodiments.

[0023] The beneficial effects of the embodiments of the present invention include, for example:

[0024] The multi-tab pole piece provided by the present invention is formed by cutting the multiple tabs through the slitting grooves. The tabs are located on both sides of the die-cut layer, that is, the middle of the die-cut layer is a tab-free area. This can reduce the risk of the tabs piercing the separator during the flattening process. It also reduces the metal debris generated during the flattening process and avoids the phenomenon of debris splashing, thereby improving the battery qualification rate and enhancing the battery product performance.

[0025] The wound battery manufacturing process provided by the present invention pre-presses the tabs and then flattens them to a predetermined height. This effectively prevents metal debris from splashing during the tab flattening process, improves the quality of the battery cell manufacturing process, and indirectly reduces production costs for the company.

[0026] The wound battery provided by the embodiment of the present invention has a higher pass rate and lower production cost, which is conducive to improving the performance of battery products. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 A schematic structural diagram of a multi-electrode pole piece provided in an embodiment of the present invention;

[0029] Figure 2 for Figure 1 A partial enlarged schematic diagram of point A in the middle;

[0030] Figure 3 A schematic diagram of the structure of a winding core formed by winding multiple pole tabs provided by an embodiment of the present invention;

[0031] Figure 4 A schematic flow chart of a wound battery preparation process according to an embodiment of the present invention.

[0032] Icon: 100-multi-electrode tab; 110-active material layer; 120-blank layer; 130-flattening layer; 140-die-cutting layer; 141-electrode tab; 1411-first end; 1413-second end; 143-cutting groove; 145-electrode-free area. DETAILED DESCRIPTION

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0034] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0035] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0036] In the description of the present invention, it should be noted that if the terms "upper", "lower", "inside", "outside", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, or is the orientation or position relationship in which the product of the invention is usually placed when in use. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be understood as a limitation on the present invention.

[0037] In addition, the terms "first", "second", etc., if used, are merely used to distinguish and describe, and should not be understood as indicating or implying relative importance.

[0038] It should be noted that, in the absence of conflict, the features in the embodiments of the present invention may be combined with each other.

[0039] After long-term research, the inventor found that during the tab flattening process, when the forward movement and rotational angular velocity of the flattening machine are too fast, the inner and outer tabs are prone to irregular folding. The folding of the outer tabs is likely to pierce the positive electrode side rubber, and the folding of the inner tabs is likely to prolong the electrolyte infiltration time; when the forward movement and rotational angular velocity are too slow, the tab gap is too large, resulting in subsequent collector plate welding explosion points, reduced production yield, and increased enterprise production costs.

[0040] Currently, the flattening process of full tabs produces a significant amount of metal debris. This scattering can easily lead to poor K-values ​​in battery cells. K-value refers to the voltage drop per unit time, typically expressed in mV / d. It is a measure of the self-discharge rate of lithium batteries. Furthermore, metal debris can easily pierce the separator, impacting the battery's yield.

[0041] In order to overcome at least one defect of the prior art, an embodiment of the present invention provides a multi-tab pole piece, a wound battery preparation process and a wound battery, which can avoid the risk of generating a large amount of metal debris and piercing the diaphragm during the flattening and extrusion process of the tab, thereby improving the product qualification rate and improving the performance of the battery product.

[0042] First embodiment

[0043] Please refer to Figure 1 This embodiment provides a multi-tab pole piece 100, including an active material layer 110 and a blank layer 120, the blank layer 120 includes a flattening layer 130 and a die-cutting layer 140 connected to each other, the flattening layer 130 is arranged on one side of the active material layer 110, and the die-cutting layer 140 is arranged on the side of the flattening layer 130 away from the active material layer 110; the die-cutting layer 140 includes a tab-free area 145 located in the middle and tab areas located on both sides; the tab area of ​​the die-cutting layer 140 is provided with a plurality of dividing grooves 143, which divide the die-cutting layer 140 into a plurality of tabs 141, and the depth of the dividing grooves 143 is less than or equal to the height of the die-cutting layer 140.

[0044] Dividing the tab area into multiple tabs 141 can reduce the splash of metal debris during the subsequent flattening process, improving product production yield. Furthermore, the tab areas are located on both sides of the die-cut layer 140; the middle portion of the die-cut layer 140 is free of tabs 141, forming a tab-free area 145. This can reduce the generation of metal debris during the flattening process, lower the risk of tabs 141 puncturing the separator during the flattening process, improve product qualification rate, and enhance battery product performance.

[0045] In an optional embodiment, the cross-sectional shape of the tab 141 is trapezoidal, rectangular, triangular, semicircular, arched, or parallelogram. Optionally, each tab 141 includes a first end 1411 connected to the flattening layer 130 and a second end 1413 distal from the flattening layer 130. The sum of the lengths of the first end 1411 and the second end 1413 is less than or equal to the sum of the height of the flattening layer 130 and the height of the tab 141. It will be readily understood that the height of the tab 141 is the vertical distance between the first end 1411 and the second end 1413. This arrangement facilitates die-cutting and improves processing efficiency.

[0046] In this embodiment, after die-cutting on the die-cutting layer 140, a plurality of tabs 141 are separated by the slitting groove 143, and the cross-section of each tab 141 is trapezoidal. Furthermore, the trapezoidal cross-section is an isosceles trapezoid. By cutting the tabs 141 into a trapezoidal shape, the generation of metal debris during the flattening process and the risk of puncturing the diaphragm can be reduced. Optionally, the depth of the slitting groove 143 is equal to the height of the die-cutting layer 140 and also equal to the height of the tab 141. The depth of the slitting groove 143 is equal to the height of the die-cutting layer 140, which can reduce the amount of metal debris generated during the flattening process.

[0047] Combine Figure 2In this embodiment, the cross-section of the tab 141 is trapezoidal, the length of the first end 1411 is the lower side length D of the trapezoid, and the length of the second end 1413 is the upper side length C of the trapezoid. The sum of the upper side length C and the lower side length D of the trapezoid is less than or equal to the sum of the height H of the flattening layer 130 and the height Z of the tab 141. It is easy to understand that the sum of the height H of the flattening layer 130 and the height Z of the tab 141 is the height of the blank layer 120. Optionally, the height of the flattening layer 130 is 0.5 to 2.0 mm, such as 0.6 mm, 0.8 mm, 1 mm or 1.5 mm; the height of the tab 141 is 4 to 9 mm, such as 4 mm, 5 mm, 6 mm, 7 mm, 8 mm or 9 mm. If the height of the tab 141 is too high, the final overcurrent capacity of the battery cell will be reduced.

[0048] It should be noted that if the cross section of the tab 141 is triangular, arched, or semicircular, the length of the second end 1413 is zero. In other optional embodiments, the shape of the tab 141 can also be set to other special shapes, which are not specifically limited here.

[0049] Combine Figure 3 Optionally, the length L of the tab-free area 145 satisfies the following relationship: L = (YXZ) * 5 * π; wherein X represents the inner diameter of the winding core formed by winding the multi-tab pole piece 100, Y represents the outer diameter of the winding core formed by winding the multi-tab pole piece 100, and Z represents the height of the tab 141; π is pi; * represents the multiplication operator.

[0050] The multi-tab pole piece 100 provided in this embodiment is designed with respect to the shape and height of the tab 141 and the length of the tab-free region 145. This facilitates the processing of the tab 141, effectively reduces the amount of metal debris generated during the flattening process, lowers the risk of metal debris puncturing the diaphragm, improves the quality rate of the battery cell process, and saves production costs. It also helps improve the problem of poor battery K value and enhances the overall performance of the battery product.

[0051] Second embodiment

[0052] Combine Figure 4 The present invention provides a process for preparing a wound battery, wherein the wound battery includes a multi-pole tab electrode sheet 100 as described in any of the aforementioned embodiments, wherein the multi-pole tab electrode sheet 100 includes a multi-pole tab 141 positive electrode sheet and a multi-pole tab 141 negative electrode sheet; the process for preparing the wound battery includes:

[0053] Step S100: stacking the separator, the positive electrode sheet of the multi-electrode tab 141, the separator and the negative electrode sheet of the multi-electrode tab 141 in sequence;

[0054] Step S200: Winding the stacked separator, the multi-tab 141 positive electrode sheet, the separator, and the multi-tab 141 negative electrode sheet to form a winding core; wherein the tabs 141 on the multi-tab 141 positive electrode sheet and the tabs 141 on the multi-tab 141 negative electrode sheet are respectively located at two ends of the winding core;

[0055] Step S300: pre-pressing the tab 141;

[0056] Step S400 : Flattening the pre-pressed tab 141 to a preset height.

[0057] In this embodiment, the tab 141 is pre-pressed first, and then the pre-pressed tab 141 is flattened to a preset height. This can better reduce the amount of metal debris generated during the flattening process, reduce the risk of metal debris puncturing the diaphragm, improve the quality rate of the battery cell process, and save production costs.

[0058] Among them, the step of pre-stressing the tabs 141 includes: pre-stressing the tabs 141 located on the inner ring and the tabs 141 on the outer ring of the winding core respectively. In an optional embodiment, the pressure of pre-stressing the tabs 141 of the inner ring is equal to the pressure of pre-stressing the tabs 141 of the outer ring. The direction of pre-stressing the tabs 141 of the inner ring is different from the direction of pre-stressing the tabs 141 of the outer ring. Optionally, different bending angles are used for pre-stressing the inner ring tabs 141 and the outer ring tabs 141. For example, the bending angle of the pre-stressing the tabs 141 of the inner ring is 120 to 165 degrees, and the bending angle of the pre-stressing the tabs 141 of the outer ring is 30 to 60 degrees. In this embodiment, the bending angle of the tab 141 of the pre-pressed inner ring is 125 to 160 degrees, such as 130 degrees, 135 degrees, 138 degrees, 140 degrees, 145 degrees, 148 degrees, 150 degrees, or 155 degrees. If the bending angle of the tab 141 of the inner ring is too small or too large, it will affect the flat pressing process in the next step and reduce the production efficiency. The bending angle of the tab 141 of the pre-pressed outer ring is 35 to 55 degrees, such as 38 degrees, 40 degrees, 45 degrees, or 50 degrees.

[0059] It can be understood that by using different pre-folding angles to pre-press the inner ring tab 141 and the outer ring tab 141, the flatness of the core end face is easier to ensure, which can greatly alleviate the diaphragm burn-through problem caused by the collecting plate welding and improve the production yield.

[0060] Pre-pressing the tabs before flattening 141 improves flattening efficiency and results. The resulting flattened surface is smoother, facilitating improved welding quality between the core and collector plate in subsequent processes. Furthermore, the flattening process reduces metal debris splashing and the risk of inverted separator insertion, improving product qualification rates, saving production costs, and increasing production efficiency.

[0061] Moreover, compared with the compactness of the full tab 141 after being flattened, the multi-tab 141 in this embodiment is flattened after being pre-pressed and bent, and has a lower compactness, which is more suitable for electrolyte infiltration, and can greatly shorten the production cycle and improve production efficiency.

[0062] It should be noted that in the step of flattening the tab 141 to a preset height, after flattening the tab 141, the height of the entire blank layer 120 is approximately equal to the height of the flattened layer 130. That is, the entire die-cut layer 140 is completely flattened and smoothed to a reasonable preset height.

[0063] The present invention also provides a wound battery, including the multi-electrode tab electrode 100 according to any of the aforementioned embodiments, or manufactured using the wound battery manufacturing process according to any of the aforementioned embodiments, which is beneficial for improving the qualified rate of wound batteries and the performance of battery products.

[0064] Some contents not mentioned in this embodiment are similar to those described in the first embodiment and will not be repeated here.

[0065] In summary, the beneficial effects of the embodiments of the present invention include:

[0066] The multi-tab pole piece 100 provided in the embodiment of the present invention is formed into a plurality of tabs 141 by cutting through the slitting groove 143. The tabs 141 are located on both sides of the die-cut layer 140, that is, the middle portion of the die-cut layer 140 is a tab-free area 145. The shape, height, and length of the tab-free area 145 are designed to reduce the risk of the tabs 141 piercing the diaphragm during the flattening process. At the same time, the metal debris generated during the flattening process is reduced, the phenomenon of debris splashing is avoided, the qualified rate of the battery is improved, and the performance of the battery product is improved.

[0067] The wound battery manufacturing process provided by the present embodiment pre-presses the tabs 141 and then flattens them to a predetermined height. This effectively prevents metal debris from splashing during the flattening process, improving the quality of the battery cell process and indirectly saving production costs for the company. Furthermore, compared to the compactness of a flattened tab 141, the multiple tabs 141 in this embodiment are flattened after pre-pressing and bending, resulting in a lower compactness and better electrolyte infiltration, significantly shortening the production cycle and improving production efficiency.

[0068] The wound battery provided by the embodiment of the present invention has a higher pass rate and lower production cost, which is conducive to improving the performance of battery products.

[0069] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A multi-electrode pole piece, characterized in that: include: active material layer; A blank layer, the blank layer comprising a flattening layer and a die-cutting layer connected to each other, the flattening layer being arranged on one side of the active material layer, and the die-cutting layer being arranged on a side of the flattening layer away from the active material layer; the die-cutting layer comprising a tab-free region in the middle and tab regions on both sides; The tab area of ​​the die-cut layer is provided with a plurality of slitting grooves, which divide the die-cut layer into a plurality of tabs, and the depth of the slitting grooves is less than or equal to the height of the die-cut layer; The length L of the tab-free area satisfies the following relationship: L=(YXZ)*5*π; wherein X represents the inner diameter of the winding core formed by winding the multi-tab pole pieces, Y represents the outer diameter of the winding core formed by winding the multi-tab pole pieces, and Z represents the height of the tab; π is pi.

2. The multi-electrode pole piece according to claim 1, characterized in that: The cross-sectional shape of the tab is trapezoidal, rectangular, triangular, semicircular, arched, or parallelogram.

3. The multi-electrode pole piece according to claim 1, characterized in that: Each of the tabs includes a first end connected to the flattening layer and a second end away from the flattening layer, and the sum of the lengths of the first end and the second end is less than or equal to the sum of the heights of the flattening layer and the tab.

4. The multi-electrode pole piece according to claim 3, characterized in that: The height of the flattened layer is 0.5-2.0 mm, and the height of the tab is 4-9 mm.

5. A process for preparing a wound battery, characterized in that: The wound battery comprises the multi-pole tab electrode sheet according to any one of claims 1 to 4, wherein the multi-pole tab electrode sheet comprises a multi-pole tab positive electrode sheet and a multi-pole tab negative electrode sheet; the wound battery preparation process comprises: stacking a separator, the multi-electrode positive electrode sheet, the separator, and the multi-electrode negative electrode sheet in sequence; The stacked separator, the multi-tab positive electrode sheet, the separator, and the multi-tab negative electrode sheet are wound to form a winding core; wherein the tabs on the multi-tab positive electrode sheet and the tabs on the multi-tab negative electrode sheet are respectively located at two ends of the winding core; pre-pressing the tab; Flatten the pre-pressed tab to a preset height.

6. The process for preparing a wound battery according to claim 5, characterized in that: The step of pre-pressing the tab comprises: The tabs on the inner circle and the tabs on the outer circle of the winding core are pre-pressed respectively.

7. The process for preparing a wound battery according to claim 6, wherein: The bending angle of the tab of the inner ring is pre-stressed to be 120-165 degrees, and the bending angle of the tab of the outer ring is pre-stressed to be 30-60 degrees.

8. A wound battery, characterized in that: The invention comprises a multi-electrode tab electrode according to any one of claims 1 to 4, or is manufactured by the winding battery preparation process according to any one of claims 5 to 7.

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