Multi-pole ear winding type battery cell, preparation method thereof and battery
Patent Information
- Application Number
- CN202611220583.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-08-12
- Publication Date
- 2026-10-09
AI Technical Summary
本发明提供了一种多极耳卷绕式电芯，通过设计阶梯式极耳转接件结构，并进一步控制极耳槽的长度与宽度的范围，有效预防极耳位析锂以及电芯的容量损失，同时能够提高极耳焊接拉力，保证焊接位的一致性，以免对电芯极耳位的过流性能造成不良影响。
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Figure CN122889852A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of battery technology, specifically relating to a multi-tab wound battery cell, its preparation method, and the battery. Background Technology
[0002] With the rapid development of the new energy industry, lithium-ion batteries are widely used in electric vehicles, consumer electronics, and energy storage due to their advantages such as high energy density and long cycle life. To further improve the energy density and power performance of batteries, the number of tabs and their welding process have become key factors. Traditional single-tab structures are prone to overheating during high-current charging and discharging, further limiting battery performance. Multi-tab structures can effectively reduce the battery's internal resistance and heat generation, but the processing technology of multi-tab structures suffers from problems such as poor welding consistency, low connection reliability, and low production efficiency.
[0003] Currently, there are two main methods for preparing multi-tab batteries: one is to set multiple current collector foil reserved areas in the length direction of the electrode sheet and weld the tabs in each reserved area; the other is a full tab structure design, that is, to cut multiple tab shapes on one side edge of the electrode sheet by die cutting and directly flattening and welding them. However, the above technical solutions still face the following challenges in practical applications: (1) After multiple tabs are welded separately, they need to be integrated into a single lead-out end in a high-efficiency and reliable manner. This integration process is the main difficulty in the process, and the existing methods often have problems such as poor welding consistency and weak connection; (2) The full tab flattening welding technology has extremely high requirements for equipment and process precision, and the welding of multi-layer current collector foil is prone to defects such as false welding and explosion welding, which affects the yield and service life of the battery.
[0004] Therefore, there is an urgent need to develop a preparation method and corresponding electrode connection structure that can efficiently and reliably integrate multiple electrodes into one unit, in order to solve the above problems. Summary of the Invention
[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a multi-tab wound battery cell and its preparation method, thereby balancing the advantages of multi-tab structure and the convenience of single-tab lead-out, and reducing the difficulty of direct welding of multi-layer current collector foil, thereby improving the fast charging performance and reliability of the battery.
[0006] To achieve this objective, the present invention employs the following technical solution: In a first aspect, the present invention provides a multi-tab wound battery cell, comprising a first electrode, a separator and a second electrode stacked and wound, wherein the first electrode and the second electrode have opposite polarities, the first electrode is provided with at least two first tab grooves, the first tabs are located in the first tab grooves, and each first tab is stacked to form a first welding part, the first welding part is connected to a first adapter piece to form a first stepped tab adapter to realize the current lead-out; And / or, the second electrode plate is provided with at least two second electrode tab grooves, the second electrode tabs are located in the second electrode tab grooves, and each second electrode tab is stacked to form a second welding part, the second welding part is connected to the second adapter plate to form a second stepped electrode tab adapter to realize the current lead-out; The lengths of the first electrode groove and the second electrode groove are each independently 10mm to 100mm, and / or the widths of the first electrode groove and the second electrode groove are each independently 10mm to 100mm.
[0007] The technical solution of the present invention provides a stepped tab adapter structure, and further controls the range of length and width in the tab groove, thereby effectively reducing the tab resistance during welding, increasing the battery overcurrent capacity, and reducing the risk of incomplete welding and weld explosion during the welding process.
[0008] Specifically, the length and width of the tab groove directly affect the current carrying capacity and current uniformity of the battery cell. In high-rate battery design, there is a strong linear positive correlation between the width of the tab groove and the rated current of the cell, while its length only needs to meet the welding process window. Furthermore, when current converges from various points on the electrode to the tab, the potential distribution along the length of the tab is not uniform. If the tab groove is wide (equivalent to a very wide tab), the current distribution along the width of the tab will be extremely uneven, meaning the current density is higher in the areas near the active material layer on both sides of the tab, while the current density is lower in the central area. To compensate for the lateral potential difference caused by the increased width, the length of the tab groove needs to be appropriately increased to allow the current to have a longer path for uniform distribution. Simultaneously, during the winding process, the tab is repeatedly bent at the winding needle. If stress concentration or tab warping / folding occurs, it can easily lead to tearing at the base of the tab, reducing the yield of the battery cell.
[0009] While wider tab slots offer greater current carrying capacity and heat dissipation area, this comes at the cost of reduced active material area, thus lowering cell capacity and energy density. More critically, the uneven current distribution caused by the tab slots significantly increases the risk of lithium plating at the negative electrode, especially in high-rate charging applications. Therefore, the design of the tab slot length and width needs to comprehensively consider multiple factors, including cell capacity loss, welding positioning accuracy, and tab welding reliability.
[0010] Based on this, the present invention effectively prevents lithium plating at the tab and capacity loss of the battery cell by separately adjusting the range of the length and width of the tab groove, while improving the tab welding pull force and ensuring the consistency of the welding position, so as not to adversely affect the overcurrent performance at the battery cell tab.
[0011] Specifically, the lengths of the first electrode groove and the second electrode groove are each independently 10mm to 100mm, for example, 10mm, 200mm, 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, 90mm or 100mm, etc., not limited to the listed values, and other unlisted values within this range are also applicable.
[0012] The width of the first electrode ear groove and the second electrode ear groove are each independently 10mm to 100mm, for example, 10mm, 20mm, 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, 90mm or 100mm, etc., not limited to the listed values, and other unlisted values within this range are also applicable.
[0013] Preferably, the ratio of the length to the width of the first electrode groove is (2~5):1, for example, it can be 2:1, 2.2:1, 2.5:1, 2.8:1, 3:1, 3.2:1, 3.5:1, 3.8:1, 4:1, 4.2:1, 4.5:1, 4.8:1 or 5:1, etc., and is not limited to the listed values. Other unlisted values within this range are also applicable.
[0014] Preferably, the ratio of the length to the width of the second electrode groove is (2~5):1, for example, it can be 2:1, 2.2:1, 2.5:1, 2.8:1, 3:1, 3.2:1, 3.5:1, 3.8:1, 4:1, 4.2:1, 4.5:1, 4.8:1 or 5:1, etc., and is not limited to the listed values. Other unlisted values within this range are also applicable.
[0015] In this invention, by adjusting the ratio of the length to the width of the tab groove to (2~5):1, the energy density, overcurrent capacity and reliability of the multi-tab wound battery cell are comprehensively improved, while reducing problems such as cell deformation and cracking caused by stress concentration.
[0016] Preferably, the product of the length and width of the first electrode groove is less than or equal to the maximum allowable capacity loss area.
[0017] Preferably, the product of the length and width of the second electrode groove is less than or equal to the maximum allowable capacity loss area.
[0018] In this invention, by adjusting the product of the length and width of the tab groove to be less than or equal to the maximum allowable capacity loss area, the energy density, overcurrent capacity and reliability of the multi-tab wound battery cell are comprehensively improved, while reducing problems such as cell deformation and cracking caused by stress concentration.
[0019] Preferably, the width of the first adapter piece and the second adapter piece are each independently 4mm to 12mm, for example, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm or 12mm, etc., not limited to the listed values, and other unlisted values within this range are also applicable.
[0020] Preferably, the thickness of the first adapter piece and the second adapter piece is independently 6mm to 20mm, for example, it can be 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm or 20mm, etc., not limited to the listed values, and other unlisted values within this range are also applicable.
[0021] Preferably, the materials of the first adapter piece and the second adapter piece include, but are not limited to, any one of aluminum, copper, nickel, silver or gold, or an alloy of at least two of them. For example, highly conductive copper-nickel composite material or nickel-copper composite material can be used, and the present invention does not limit this.
[0022] Preferably, the first electrode includes a first current collector and a first active material layer and a second active material layer located on opposite sides of the thickness direction of the first current collector, and the first electrode tab groove is disposed at least one of the head, middle or tail of the first electrode.
[0023] In this invention, the composition of the first active material layer and the second active material layer may be the same or different, and this invention does not limit this.
[0024] Preferably, the first electrode lug groove is provided with a third welding part, the first electrode lug is connected to the first current collector through the third welding part, and a free section is reserved between the third welding part and the first welding part, thereby forming a stress buffer structure, which significantly improves the vibration resistance and reliability of the overall connection.
[0025] Preferably, the second electrode includes a second current collector and a third active material layer and a fourth active material layer located on opposite sides of the thickness direction of the second current collector, and the second electrode tab is disposed at least one of the head, middle or tail of the second electrode.
[0026] In this invention, the compositions of the third active material layer and the fourth active material layer may be the same or different, and this invention does not impose any restrictions on this.
[0027] Preferably, the second electrode lug groove is provided with a fourth welding part, the second electrode lug is connected to the second current collector through the fourth welding part, and a free section is reserved between the fourth welding part and the second welding part, thereby forming a stress buffer structure, which significantly improves the vibration resistance and reliability of the overall connection.
[0028] In this invention, by adjusting the width and thickness of the adapter piece to a reasonable range and reserving free sections between different welding parts, a "micro-stress buffer" is constructed. This buffer absorbs and dissipates the mechanical stress generated during winding and charging / discharging, ensuring it stays away from the vulnerable areas of the tab welding. Simultaneously, through further optimization of the composite properties parameters, the formation of intermetallic compounds is fundamentally avoided, completely opening a low-impedance path from the tab to the external circuit, significantly reducing connection resistance, and achieving a lossless connection.
[0029] Preferably, such as Figures 1 to 2 As shown, the first tab groove is disposed in the region of any one or at least a combination of two of the first active material layer, the second active material layer, or the first current collector.
[0030] As an example, the first tab groove can be set in the following positions: one of the first tab grooves is set at the head of the first electrode, which is the foil area and does not require tab groove cleaning; the remaining first tab grooves are set in the active material layer area.
[0031] Preferably, such as Figures 1 to 2 As shown, the second electrode groove is disposed in the region of any one or at least a combination of two of the third active material layer, the fourth active material layer, or the second current collector.
[0032] As an example, the second tab groove can be set in the following positions: one of the second tab grooves is set at the head of the second electrode, which is the foil area and does not require tab groove cleaning; the remaining second tab grooves are set in the active material layer area.
[0033] In a second aspect, the present invention provides a method for preparing a multi-pole wound battery cell according to the first aspect, the method comprising the following steps: Provide a first and a second electrode with opposite polarities; Set the position and size of the first tab groove on the first electrode plate, remove the single-sided active material layer on the corresponding position of the first tab groove to expose the metal current collector, form at least two first tab grooves, and weld the first tab in the first tab groove; Set the position and size of the second electrode tab groove on the second electrode plate, remove the single-sided active material layer on the corresponding position of the second electrode tab groove to expose the metal current collector, form at least two second electrode tab grooves, and weld the second electrode tab in the second electrode tab groove; The first electrode, the diaphragm, and the second electrode are stacked and wound together to form a wound structure, such that at least two tabs of the same polarity are led outward from the same end of the cell; Each of the first tabs after winding is stacked and welded to the first adapter piece to form a first welded part, thereby obtaining a first stepped tab adapter to realize the extraction of current; And / or, each of the second tabs after winding is stacked and welded to the second adapter piece to form a second welded part, to obtain a second stepped tab adapter to realize the current lead-out, and to obtain the multi-tab wound battery cell. The lengths of the first electrode groove and the second electrode groove are each independently 10mm to 100mm, and / or the widths of the first electrode groove and the second electrode groove are each independently 10mm to 100mm.
[0034] In the preparation method provided by this invention, the multiple tab grooves on the electrode sheet are first cleaned on one side and the tabs are welded together. After being wound into shape, the multiple independent tabs are then welded together again with an adapter plate. This preparation method balances the advantages of a multi-tab structure and the convenience of single-tab lead-out, and simplifies the cell welding process.
[0035] Preferably, the ratio of the length to the width of the first electrode groove is (2~5):1, for example, it can be 2:1, 2.2:1, 2.5:1, 2.8:1, 3:1, 3.2:1, 3.5:1, 3.8:1, 4:1, 4.2:1, 4.5:1, 4.8:1 or 5:1, etc., and is not limited to the listed values. Other unlisted values within this range are also applicable.
[0036] Preferably, the ratio of the length to the width of the second electrode groove is (2~5):1, for example, it can be 2:1, 2.2:1, 2.5:1, 2.8:1, 3:1, 3.2:1, 3.5:1, 3.8:1, 4:1, 4.2:1, 4.5:1, 4.8:1 or 5:1, etc., and is not limited to the listed values. Other unlisted values within this range are also applicable.
[0037] Preferably, the method of removing the single-sided active material layer on the corresponding position of the first electrode groove to expose the metal current collector includes laser cleaning or mechanical scraping.
[0038] Preferably, the method of removing the single-sided active material layer on the corresponding position of the second electrode groove to expose the metal current collector includes laser cleaning or mechanical scraping.
[0039] Preferably, the first electrode tab is welded in the first electrode tab groove to form a third welding part, and the weld mark shape of the third welding part includes a continuous strip weld mark or a discontinuous strip weld mark.
[0040] Preferably, the second electrode tab is welded in the second electrode tab groove to form a fourth welding part, and the weld mark shape of the fourth welding part includes a continuous strip weld mark or a discontinuous strip weld mark.
[0041] Preferably, in the process of setting each of the first tabs after winding and welding them to the first adapter piece to form the first welded part, the welding method includes ultrasonic welding or laser welding.
[0042] Preferably, in the process of stacking each of the wound second tabs and welding them with the second adapter piece to form the second welded part, the welding method includes ultrasonic welding or laser welding.
[0043] Thirdly, the present invention provides a battery comprising a housing and a multi-tab wound cell according to the first aspect, the multi-tab wound cell being located within the housing.
[0044] The numerical range described in this invention includes not only the point values listed above, but also any point values within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values included in the range.
[0045] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a multi-tab wound battery cell. By designing a stepped tab adapter structure and further controlling the length and width range of the tab groove, it effectively prevents lithium plating at the tab position and capacity loss of the battery cell. At the same time, it can improve the tab welding pull force and ensure the consistency of the welding position, so as not to adversely affect the overcurrent performance of the battery cell tab position. Attached Figure Description
[0046] Figure 1 This is a schematic diagram of the structure after multiple tabs are welded onto the electrode sheet, as provided in some embodiments of the present invention.
[0047] Figure 2 This is a schematic diagram of the structure after multiple tabs are welded onto the electrode sheet, as provided in some other embodiments of the present invention.
[0048] Figure 3 This is a schematic diagram of the tab distribution of the wound battery cell provided by the present invention.
[0049] Figure 4 This is a schematic diagram of the stepped electrode adapter provided by the present invention.
[0050] Figure 5 This is a schematic diagram of the battery structure provided by the present invention. Detailed Implementation
[0051] The technical solution of the present invention will be further described below with reference to specific embodiments and accompanying drawings. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be considered as specific limitations thereof.
[0052] Example 1 This embodiment provides a multi-tab wound battery cell containing a negative electrode sheet with a bipolar tab structure and its preparation method, such as... Figure 3 As shown, it includes the following steps: (1) Negative electrode pretreatment: Take a negative electrode, which includes a copper foil current collector and a first artificial graphite active material layer and a second artificial graphite active material layer located on opposite sides of the copper foil current collector in the thickness direction. The first artificial graphite active material layer and the second artificial graphite active material layer are both composed of artificial graphite, conductive agent Super P, binder styrene-butadiene latex and thickener sodium carboxymethyl cellulose in a mass ratio of 92:2:3:3. In the area reserved along the length of the current collector foil of the negative electrode sheet, the positions and dimensions of the two negative electrode tab grooves (length 25mm, width 10mm) are set. Using laser cleaning, the single-sided artificial graphite active material layer at the corresponding positions of the two negative electrode tab grooves is precisely removed until the copper foil current collector is exposed, forming two negative electrode tab grooves, while ensuring that the artificial graphite active material layer on the other side remains intact.
[0053] (2) First welding (negative electrode tab welding): Using a laser welding machine, nickel tabs are placed in the two negative electrode tab slots respectively, and the negative electrode tabs are firmly welded to the copper foil current collector through continuous strip welding to form the first welding part.
[0054] (3) Winding: The negative electrode sheet with the welded negative electrode tabs, the separator, and the NCM811 positive electrode sheet are stacked in sequence and wound into a square bare cell. After winding, the two negative electrode tabs with the same polarity are led out from the same end of the cell.
[0055] (4) Secondary welding (transfer welding): Arrange the two protruding negative electrode tabs so that they are parallel and overlapped. Using an ultrasonic welding machine, weld the ends of the two overlapped negative electrode tabs to a nickel lead sheet (6mm wide and 13mm thick) to form a second welded part, resulting in the following: Figure 4 The stepped tab adapter shown is used to extract current.
[0056] (5) Final structure: In the formed stepped electrode adapter structure, a free section is naturally reserved between the first welding part and the second welding part, which can effectively buffer the stress during subsequent shell insertion, liquid injection and use.
[0057] Example 2 This embodiment provides a multi-tab wound battery cell with a negative electrode sheet including a bipolar tab structure and a method for its fabrication, which includes the following steps: (1) Negative electrode pretreatment: Take a negative electrode, which includes a copper foil current collector and a first artificial graphite active material layer and a second artificial graphite active material layer located on opposite sides of the copper foil current collector in the thickness direction. The first artificial graphite active material layer and the second artificial graphite active material layer are both composed of artificial graphite, conductive agent Super P, binder styrene-butadiene latex and thickener sodium carboxymethyl cellulose in a mass ratio of 92:2:3:3. In the area reserved along the length of the current collector foil of the negative electrode sheet, the positions and dimensions of the two negative electrode tab grooves (length 20mm, width 10mm) are set. Using laser cleaning, the single-sided artificial graphite active material layer at the corresponding positions of the two negative electrode tab grooves is precisely removed until the copper foil current collector is exposed, forming two negative electrode tab grooves, while ensuring that the artificial graphite active material layer on the other side remains intact.
[0058] (2) First welding (negative electrode tab welding): Using a laser welding machine, nickel tabs are placed in the two negative electrode tab slots respectively, and the negative electrode tabs are firmly welded to the copper foil current collector through continuous strip welding to form the first welding part.
[0059] (3) Winding: The negative electrode sheet with the welded negative electrode tabs, the separator, and the NCM811 positive electrode sheet are stacked in sequence and wound into a cylindrical or square bare cell. After winding, the two negative electrode tabs with the same polarity are led out from the same end of the cell.
[0060] (4) Secondary welding (transfer welding): The two protruding negative electrode tabs are arranged to overlap in parallel. Using an ultrasonic welding machine, the ends of the two overlapped negative electrode tabs are welded to a nickel lead-out piece (4mm wide and 6mm thick) to form a second welded part, thus obtaining a stepped electrode tab adapter to realize the current extraction.
[0061] (5) Final structure: In the formed stepped electrode adapter structure, a free section is naturally reserved between the first welding part and the second welding part, which can effectively buffer the stress during subsequent shell insertion, liquid injection and use.
[0062] Example 3 This embodiment provides a multi-tab wound battery cell with a negative electrode sheet including a bipolar tab structure and a method for its fabrication, which includes the following steps: (1) Negative electrode pretreatment: Take a negative electrode, which includes a copper foil current collector and a first artificial graphite active material layer and a second artificial graphite active material layer located on opposite sides of the copper foil current collector in the thickness direction. The first artificial graphite active material layer and the second artificial graphite active material layer are both composed of artificial graphite, conductive agent Super P, binder styrene-butadiene latex and thickener sodium carboxymethyl cellulose in a mass ratio of 92:2:3:3. In the area reserved along the length of the current collector foil of the negative electrode sheet, the positions and dimensions of the two negative electrode tab grooves (length 50mm, width 10mm) are set. Using laser cleaning, the single-sided artificial graphite active material layer at the corresponding positions of the two negative electrode tab grooves is precisely removed until the copper foil current collector is exposed, forming two negative electrode tab grooves, while ensuring that the artificial graphite active material layer on the other side remains intact.
[0063] (2) First welding (negative electrode tab welding): Using a laser welding machine, nickel tabs are placed in the two negative electrode tab slots respectively, and the negative electrode tabs are firmly welded to the copper foil current collector through continuous strip welding to form the first welding part.
[0064] (3) Winding: The negative electrode sheet with the welded negative electrode tabs, the separator, and the NCM811 positive electrode sheet are stacked in sequence and wound into a cylindrical or square bare cell. After winding, the two negative electrode tabs with the same polarity are led out from the same end of the cell.
[0065] (4) Secondary welding (transfer welding): The two protruding negative electrode tabs are arranged to overlap in parallel. Using an ultrasonic welding machine, the ends of the two overlapped negative electrode tabs are welded to a nickel lead-out piece (12mm wide and 20mm thick) to form the second welding part, thus obtaining the first-step electrode tab adapter to realize the current extraction.
[0066] (5) Final structure: In the formed stepped electrode adapter structure, a free section is naturally reserved between the first welding part and the second welding part, which can effectively buffer the stress during subsequent shell insertion, liquid injection and use.
[0067] Example 4 This embodiment provides a multi-tab wound battery cell with a positive electrode sheet including a three-tab structure and its preparation method, which includes the following steps: (1) Positive electrode pretreatment: Take a positive electrode, which includes an aluminum foil current collector and a first NCM811 active material layer and a second NCM811 active material layer located on opposite sides of the thickness direction of the aluminum foil current collector. The first NCM811 active material layer and the second NCM811 active material layer are both composed of NCM811 positive electrode active material, conductive agent Super P and binder polyvinylidene fluoride in a mass ratio of 90:5:5. In the region along the length of the positive electrode sheet, define the position and size of three positive electrode tab grooves (25mm in length and 10mm in width). Using a mechanical scraping tool, scrape the single-sided NCM811 active material layer at the corresponding position of the three positive electrode tab grooves on one side until the aluminum foil current collector is exposed, forming three positive electrode tab grooves, while ensuring that the NCM811 active material layer on the other side remains intact.
[0068] (2) First welding (positive electrode tab welding): Using a laser welding machine, pure aluminum tabs are welded to the three positive electrode tab grooves to form the first welding part. The shape of the weld mark is a discontinuous strip weld mark to ensure the connection strength and flow area.
[0069] (3) Winding and forming: The positive electrode sheet with the welded positive electrode tabs, the separator, and the artificial graphite negative electrode sheet are wound and stacked in sequence to form a square bare cell. After winding, the three positive electrode tabs with the same polarity are led out from the same end of the cell.
[0070] (4) Secondary welding (transfer welding): The three protruding positive electrode tabs are arranged to be stacked in parallel. In view of the characteristics of aluminum, laser welding is used to weld the ends of the stacked three positive electrode tabs to an aluminum lead-out piece (6mm wide and 13mm thick) to form a second welding part, so as to obtain a stepped electrode tab adapter to realize the current lead-out.
[0071] (5) Final structure: In the formed stepped electrode adapter structure, a free section is naturally reserved between the first welding part and the second welding part as a stress release zone, which enhances the fatigue resistance of the structure.
[0072] Example 5 The difference between this embodiment and embodiment 1 is that in step (1), laser cleaning is used to precisely remove the double-sided artificial graphite active material layer on the corresponding positions of the two negative electrode tabs until the copper foil current collector is exposed. Everything else is the same as in embodiment 1.
[0073] Example 6 The difference between this embodiment and embodiment 4 is that in step (1), a mechanical scraping tool is used to scrape the double-sided NCM811 active material layer on the corresponding positions of the three positive electrode tabs until the aluminum foil current collector is exposed. Everything else is the same as in embodiment 4.
[0074] Comparative Example 1 The difference between this comparative example and Example 1 is that the length of the negative electrode tab groove is adjusted to 15mm and the width to 30mm, so that the ratio of the length to the width of the negative electrode tab groove is 0.5:1, which is the same as in Example 1.
[0075] Comparative Example 2 The difference between this comparative example and Example 1 is that the length of the negative electrode tab groove is adjusted to 80mm and the width to 10mm, so that the ratio of the length to the width of the negative electrode tab groove is 8:1. Everything else is the same as in Example 1.
[0076] Comparative Example 3 The difference between this comparative example and Example 4 is that the length of the positive electrode slot is adjusted to 15mm and the width to 30mm, so that the ratio of the length to the width of the negative electrode slot is 0.5:1. Everything else is the same as in Example 4.
[0077] Comparative Example 4 The difference between this comparative example and Example 4 is that the length of the positive electrode slot is adjusted to 80mm and the width to 10mm, so that the ratio of the length to the width of the negative electrode slot is 8:1. All other aspects are the same as in Example 4. Test conditions After placing the multi-pole wound battery cells prepared in the above embodiments and comparative examples into the housing, they are assembled as follows: Figure 5 The battery shown was then subjected to electrochemical performance testing, and the testing method is as follows: (1) Battery capacity The batteries assembled in the above embodiments and comparative examples were charged at 25°C with a constant current of 0.5C to 4.35V, then charged with a constant voltage of 0.05C; then discharged at 0.5C to 3.0V, and the capacity of the batteries at this time was measured.
[0078] (2) Fast charging performance The capacity retention rate of the batteries assembled in the above embodiments and comparative examples was tested after cycling 500 times at 25°C and 3C.
[0079] The test results are shown in Table 1.
[0080] Table 1 As can be seen from Table 1, the multi-tab wound cells provided in Examples 1 to 4 of the present invention can effectively reduce internal resistance, improve current distribution, and suppress local temperature rise and stress concentration by appropriately increasing the length and width of the tab slots, thereby significantly improving the battery capacity retention rate in 500 high-rate cycles at room temperature.
[0081] Comparing Examples 1, 5, and 6, it is evident that the existence of the tab groove essentially sacrifices a portion of the active material coating area to gain space for tab welding. The wider the tab groove, the wider the area of active material removed along the width of the electrode, resulting in a more significant capacity loss. Furthermore, while a longer tab groove is beneficial for welding operations and uniform current distribution, it occupies more electrode length space, reducing the total amount of active material on the entire electrode. Consequently, under the same comparative conditions, the battery's capacity retention rate decreases.
[0082] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.
Claims
1. A multi-electrode wound battery cell, comprising a first electrode, a separator, and a second electrode, wherein the first electrode and the second electrode have opposite polarities, characterized in that, The first electrode plate is provided with at least two first electrode tab grooves, the first electrode tabs are located in the first electrode tab grooves, and each first electrode tab is stacked to form a first welding part. The first welding part is connected to the first adapter plate to form a first stepped electrode tab adapter to realize the current lead-out. And / or, the second electrode plate is provided with at least two second electrode tab grooves, the second electrode tabs are located in the second electrode tab grooves, and each second electrode tab is stacked to form a second welding part, the second welding part is connected to the second adapter plate to form a second stepped electrode tab adapter to realize the current lead-out; The lengths of the first electrode groove and the second electrode groove are each independently 10mm to 100mm, and / or the widths of the first electrode groove and the second electrode groove are each independently 10mm to 100mm.
2. The multi-pole wound battery cell according to claim 1, characterized in that, The ratio of the length to the width of the first pole ear groove is (2~5):1; And / or, the ratio of the length to the width of the second pole ear groove is (2~5):
1.
3. The multi-pole wound battery cell according to claim 1 or 2, characterized in that, The width of the first adapter piece and the second adapter piece are each independently 4mm to 12mm; And / or, the thickness of the first adapter piece and the second adapter piece are each independently 6mm to 20mm.
4. The multi-pole wound battery cell according to claim 1, characterized in that, The first electrode includes a first current collector and a first active material layer and a second active material layer located on opposite sides of the thickness direction of the first current collector, and the first electrode tab groove is disposed at least one of the head, middle or tail of the first electrode. And / or, the first electrode lug groove is provided with a third welding part, the first electrode lug is connected to the first current collector through the third welding part, and a free section is reserved between the third welding part and the first welding part; And / or, the second electrode includes a second current collector and a third active material layer and a fourth active material layer located on opposite sides of the thickness direction of the second current collector, and the second electrode ear groove is disposed at least one of the head, middle or tail of the second electrode. And / or, the second electrode lug groove is provided with a fourth welding part, the second electrode lug is connected to the second current collector through the fourth welding part, and a free section is reserved between the fourth welding part and the second welding part.
5. The multi-pole wound battery cell according to claim 4, characterized in that, The first tab groove is disposed in a region of any one or at least a combination of two of the first active material layer, the second active material layer, or the first current collector; And / or, the second electrode groove is disposed in a region of any one or at least a combination of two of the third active material layer, the fourth active material layer, or the second current collector.
6. A method for preparing a multi-pole wound battery cell according to any one of claims 1 to 5, characterized in that, The preparation method includes the following steps: Provide a first and a second electrode with opposite polarities; Set the position and size of the first tab groove on the first electrode plate, remove the single-sided active material layer on the corresponding position of the first tab groove to expose the metal current collector, form at least two first tab grooves, and weld the first tab in the first tab groove; Set the position and size of the second electrode tab groove on the second electrode plate, remove the single-sided active material layer on the corresponding position of the second electrode tab groove to expose the metal current collector, form at least two second electrode tab grooves, and weld the second electrode tab in the second electrode tab groove; The first electrode, the diaphragm, and the second electrode are stacked and wound together to form a wound structure, such that at least two tabs of the same polarity are led outward from the same end of the cell; Each of the first tabs after winding is stacked and welded to the first adapter piece to form a first welded part, thereby obtaining a first stepped tab adapter to realize the extraction of current; And / or, each of the second tabs after winding is stacked and welded to the second adapter piece to form a second welded part, to obtain a second stepped tab adapter to realize the current lead-out, and to obtain the multi-tab wound battery cell. The lengths of the first electrode groove and the second electrode groove are each independently 10mm to 100mm, and / or the widths of the first electrode groove and the second electrode groove are each independently 10mm to 100mm.
7. The preparation method according to claim 6, characterized in that, The method of removing the single-sided active material layer on the corresponding position of the first electrode groove to expose the metal current collector includes laser cleaning or mechanical scraping. And / or, the method of removing the single-sided active material layer on the corresponding position of the second electrode ear groove to expose the metal current collector includes laser cleaning or mechanical scraping.
8. The preparation method according to claim 6, characterized in that, The first electrode tab is welded in the first electrode tab groove to form a third welding part. The weld mark shape of the third welding part includes a continuous strip weld mark or a discontinuous strip weld mark. And / or, the welding of the second electrode tab in the second electrode tab groove to form a fourth welding part, wherein the weld mark shape of the fourth welding part includes a continuous strip weld mark or a discontinuous strip weld mark.
9. The preparation method according to claim 6, characterized in that, In the process of setting up each of the first electrode tabs after winding and welding them with the first adapter piece to form a first welded part, the welding method includes ultrasonic welding or laser welding. And / or, in the process of setting each of the wound second tabs into a stack and welding it to the second adapter piece to form a second welded part, the welding method includes ultrasonic welding or laser welding.
10. A battery, characterized in that, The battery includes a housing and a multi-tab wound cell according to any one of claims 1 to 5, wherein the multi-tab wound cell is located in the housing.