Tab, cell, and solid-state battery

Abstract

The application provides a tab of a battery, a battery cell and a solid-state battery. The tab has a longitudinal folding structure, and the number of foldings is greater than or equal to 2. The longitudinal direction is perpendicular to the joint boundary of the tab and the electrode tab. The longitudinal folding structure is used to absorb the longitudinal stress generated by the expansion of the electrode material. The folding generates a plurality of sub-folding pieces. The surface of each sub-folding piece includes a groove. The groove is used to absorb the transverse stress generated by the expansion of the electrode material. Through the synergistic effect of the transverse groove and the longitudinal folding, the problem that the tab is prone to breaking when the electrode material expands is solved, and the service life of the tab is improved.

Description

Technical Field

[0001] This application relates to the field of batteries, and more particularly to a battery tab, a battery cell, and a solid-state battery. Background Technology

[0002] Solid-state batteries have become the core direction of the next generation of energy storage technology due to their advantages such as high energy density, high safety and long cycle life, and have broad application prospects, especially in the fields of new energy vehicles, aerospace and energy storage power stations.

[0003] All-solid-state battery cells, by employing high-specific-capacity silicon-based materials or lithium metal as the negative electrode, can significantly improve battery energy density, thereby extending driving range and reducing charging frequency. However, during charging and discharging, the dramatic volume expansion (up to 300%-400%) of the silicon-based negative electrode due to alloying reactions and the dendrite growth of the lithium metal negative electrode both lead to significant mechanical stress in the tab area. As a key structure for current transmission within the battery, the tab must simultaneously withstand the longitudinal tensile force and transverse shear force generated by material expansion. The risk of its fracture can directly cause an internal open circuit within the cell, leading to a sharp drop in battery performance or even thermal runaway.

[0004] Therefore, how to solve the problem of tab breakage through structural optimization has become a key technical bottleneck for the application of all-solid-state battery cells. Summary of the Invention

[0005] This application provides a battery tab, a battery cell, and a solid-state battery to solve the problem of tab breakage and improve the service life of the tab.

[0006] In a first aspect, this application provides a battery tab, the tab having a longitudinal folding structure with ≥2 folding times, the longitudinal direction being perpendicular to the boundary between the tab and the electrode sheet, the longitudinal folding structure being used to absorb the longitudinal stress generated by the expansion of the electrode material;

[0007] Folding produces multiple sub-folded pieces, each of which has a groove on its surface to absorb lateral stress generated by the expansion of the electrode material.

[0008] Furthermore, the sum of the opening areas of all the grooves of the electrode tab accounts for 0.1% to 50% of the surface area of ​​the electrode tab.

[0009] Furthermore, the depth of the groove is 0.1% to 50% of the thickness of the electrode tab.

[0010] Furthermore, the grooves of at least two adjacent sub-folds are arranged in a staggered pattern.

[0011] Furthermore, the width of the sub-folded piece is 0.01~3cm, and / or the depth of the groove is 0.2~10μm.

[0012] Furthermore, on the surface of the sub-folded sheet, grooves are arranged laterally, the laterally being parallel to the boundary between the tab and the electrode sheet.

[0013] Furthermore, the spacing between adjacent grooves is 0.5 to 100 times the maximum lateral width of the groove;

[0014] And / or, in the longitudinal direction, the spacing between adjacent grooves is 0.5 to 40 times the maximum longitudinal length of the groove.

[0015] Furthermore, the angle between adjacent sub-folds is 10~170°.

[0016] Secondly, this application provides a battery cell, the battery cell comprising a positive electrode, a negative electrode, and an electrolyte, wherein the negative electrode or the positive electrode is welded with the tabs described in any one of the first aspects.

[0017] Thirdly, this application provides a solid-state battery, which includes the battery cell described in the second aspect.

[0018] This application provides a battery tab, a battery cell, and a solid-state battery. The tab has a longitudinal folding structure with a folding count of ≥2. The longitudinal direction is perpendicular to the boundary between the tab and the electrode sheet. The longitudinal folding structure is used to absorb the longitudinal stress generated by the expansion of the electrode material. Folding creates multiple sub-folded sheets, each of which has a groove on its surface to absorb the lateral stress generated by the expansion of the electrode material. Through the synergistic effect of the lateral and longitudinal folds, the problem of the tab easily breaking when the electrode material expands is solved, thus improving the service life of the tab. Attached Figure Description

[0019] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0020] Figure 1 A schematic diagram of the tab structure of a battery provided in this application;

[0021] Figure 2 The capacity retention rate variation graphs of Example 1 and Comparative Example 1 provided in this application.

[0022] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0023] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as any other stated value or each smaller range between intermediate values ​​within a range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0024] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This application specification and embodiments are merely exemplary.

[0025] In existing technologies, solutions to the problem of tab breakage mainly focus on material modification. For example, the volume expansion of silicon-based materials can be mitigated by using nano-sized silicon-based materials, carbon coating technology, or constructing porous structures; the interfacial stability between the electrode and the tab can be improved by optimizing the binder formulation; or the expansion rate can be reduced by using composite material design. However, the above methods have significant limitations: 1) Material modification processes are complex and costly (e.g., the preparation of nano-silicon requires high-energy ball milling or chemical vapor deposition), making it difficult to achieve large-scale production; 2) Some modification methods (such as surface coating) may introduce side reactions, causing the electrode material to peel off or generate gas during cycling, further aggravating the tab stress; 3) Even after modification, the expansion rate of silicon-based anodes is still as high as about 30%, far exceeding the 10% of traditional graphite anodes, making it impossible to completely avoid tab breakage; 4) Existing methods are mainly aimed at silicon-based anodes and lack universality for the expansion problems of materials such as lithium metal anodes and ternary cathodes.

[0026] Therefore, there is an urgent need for an optimized electrode structure that does not rely on material modification and can be applied to various electrode systems.

[0027] In view of this, this application constructs a dual-functional structure for mechanical stress buffering and thermal strain suppression through a three-dimensional design of the tab structure, namely longitudinal folding and transverse groove setting. By optimizing the mechanical structure instead of traditional material modification, the risk of tab breakage is reduced by increasing the longitudinal flexibility (folding design) and transverse stress release path (groove design) of the tab.

[0028] Longitudinal folding can dynamically adapt to the longitudinal expansion of electrode materials, while grooves alleviate lateral shear force and thermal strain accumulation by releasing local stress concentration and increasing surface area, while improving heat dissipation efficiency, providing a structural solution for the high safety and long cycle life of all-solid-state cells.

[0029] It should be noted that the tab structure of this application is not only applicable to the electrode of solid-state batteries, but also applicable to the electrode of liquid batteries with volume expansion.

[0030] Figure 1 This application provides a schematic diagram of the tab structure of a battery, as shown below. Figure 1 As shown, the tab has a longitudinal folding structure with ≥2 folds. The longitudinal direction is perpendicular to the junction of the tab and the electrode plate. The longitudinal folding structure is used to absorb the longitudinal stress generated by the expansion of the electrode material.

[0031] Folding produces multiple sub-folded sheets, each with a groove on its surface to disperse the lateral stress generated by the expansion of the electrode material.

[0032] The longitudinal folding structure, through multiple folds along the length of the tab, creates an elastically deformable region. When the electrode material expands longitudinally during charging and discharging, the folding structure absorbs the stress generated by the expansion through deformation, preventing stress concentration at the end of the tab. Each sub-fold has a groove structure, which forms a local stress release path. When the electrode material generates lateral shear force, the lateral shear force is gradually dispersed at the edge of the groove, rather than concentrated at a certain location on the tab. At the same time, the groove structure increases the surface area of ​​the tab, providing additional channels for heat dissipation and reducing the accumulation of local thermal strain. Through the synergistic effect of the longitudinal folding structure and the groove structure, the tab maintains structural integrity under complex stress environments, improves the lifespan of the tab, reduces the risk of tab breakage, and enhances the cycle life and thermal stability of the battery cell.

[0033] exist Figure 1 The electrode tabs are welded onto the negative electrode sheet, solving the problem of negative electrode tab breakage due to electrode material expansion. Through the optimized tab structure, the problem of tab breakage caused by volume expansion of various positive and negative electrode materials during charging and discharging can be solved. Positive electrodes include, but are not limited to, ternary positive electrodes, lithium-rich manganese-based positive electrodes, and lithium iron phosphate positive electrodes, while negative electrodes include, but are not limited to, silicon-based negative electrodes, lithium metal negative electrodes, and graphite negative electrodes.

[0034] The vertical folding design of the tabs also increases the surface area of ​​the tabs, enhances heat dissipation performance, and effectively avoids safety issues caused by heat accumulation.

[0035] Current methods of carbon coating and nano-sizing of silicon-based anodes compromise their performance, significantly reducing the specific capacity and energy density of the cell. However, creating transverse grooves on the tabs not only mitigates the thermal strain effects of lateral thermal stress but also reduces the weight of the tabs, thereby increasing the cell's energy density.

[0036] In some embodiments, the longitudinal folding structure can be a Z-shaped fold, an L-shaped fold, or an N-shaped fold. For example, the tab is folded every 2 mm along its length to form a continuous Z-shaped structure. For example, the tab is bent 90° to one side every 3 mm to form an L-shaped fold. As another example, the tab is alternately bent to both sides every 1 mm along its length to form an N-shaped structure.

[0037] Z-shaped folds, through continuous changes in bending direction, evenly distribute longitudinal stress; L-shaped folds, through alternating right-angle bends, enhance local tensile strength; and N-shaped folds, through bidirectional alternating bends, balance stress distribution. These structural forms can absorb the longitudinal stress generated by the expansion of the electrode material through elastic deformation characteristics, preventing stress concentration at the tip of the tab. Differentiated designs using Z-shaped, L-shaped, or N-shaped folds can be adapted to the expansion characteristics of different electrode materials. For example, Z-shaped folds are suitable for the continuous expansion of silicon-based anodes, L-shaped folds are suitable for the localized stress release of lithium metal anodes, and N-shaped folds are suitable for the bidirectional stress balance of ternary cathodes. This structural diversity significantly improves the adaptability of the tabs in complex expansion environments, further reducing the risk of breakage.

[0038] The number of folds can range from 2 to 100, or even more, depending on the length of the tab.

[0039] In some embodiments, the included angle between two adjacent sub-folds is 10 to 170°, such as 10°, 30°, 60°, 90°, 120°, 150°, 170°, or any combination of the above.

[0040] The number of grooves on a single sub-folded tab can be 1, 2, 3, 10, 20 or more.

[0041] In some embodiments, the sum of the opening areas of all the grooves in the tab accounts for 0.1% to 50% of the tab surface area. For example, 0.1%, 1%, 5%, 10%, 20%, 30%, 50%, or any combination thereof. The opening area of ​​the groove represents the area of ​​the groove parallel to the tab surface. A sum of opening areas accounting for 0.1% to 50% of the tab surface area indicates that the groove occupies less than half the area, thus reducing the impact on the mechanical strength of the tab material while absorbing lateral stress.

[0042] In some embodiments, the depth of each groove is 0.1% to 50% of the tab thickness, for example, 0.1%, 1%, 5%, 10%, 20%, 30%, 50%, or any combination thereof. A groove depth greater than 0.1% is beneficial for absorbing lateral shear forces, while a depth less than 50% reduces the impact on the current conduction path. For example, the total thickness of the tab current collector is 100 μm, and the groove depth at the tab portion is 0.1 μm to 50 μm.

[0043] The grooves have depth; therefore, adding a groove structure increases the surface area of ​​the tab, and the increase in surface area is related to the groove depth. In one embodiment, the groove arrangement increases the total surface area of ​​the tab by 0.1% to 80% compared to a tab without a groove. Preferably, the grooves increase the total surface area by 1% to 10%, within which range the lifespan of the tab is significantly improved without affecting battery performance.

[0044] In some embodiments, the grooves of at least two adjacent sub-folds are staggered. This staggered arrangement helps to avoid stress cracking caused by stress concentration along a single line.

[0045] The staggered longitudinal arrangement of the grooves breaks the uniform stress distribution pattern of traditional planar tabs, allowing the lateral shear force to form independent stress release paths at the edges of multiple grooves. For example, when the electrode material undergoes lateral displacement due to expansion, the asymmetric structure of the staggered grooves allows stress to be gradually transferred between adjacent grooves, rather than concentrating at a single location. This design significantly reduces the stress concentration effect in the tab-electrode connection area, avoiding fracture caused by local stress exceeding the material's strength limit.

[0046] In some embodiments, adjacent rows of grooves in the longitudinal direction do not overlap. For example, the first row of grooves is located on the left side of the sub-fold, the second row of grooves is located on the right side of the sub-fold, the third row of grooves is again located on the left side, and so on in a cycle.

[0047] The longitudinally staggered arrangement of the transverse grooves breaks the uniform stress distribution pattern of traditional planar electrodes through an asymmetrical distribution. When the electrode material undergoes lateral displacement due to expansion, the staggered grooves allow stress to be gradually transmitted across multiple independent regions, rather than concentrating at a single location. For example, after the first row of grooves absorbs part of the lateral shear force, the second row of grooves further disperses the remaining stress through their staggered positions, thereby avoiding fracture caused by localized stress concentration.

[0048] In the longitudinal direction, the grooves are staggered between every 2 adjacent sub-folds and between every 20 adjacent sub-folds. For example, the grooves are staggered between every 10 adjacent sub-folds, meaning that in the longitudinal direction, the position of the grooves cycles every 10 rows.

[0049] In some embodiments, grooves are arranged laterally on the surface of the sub-folded sheet, with the lateral direction parallel to the boundary between the tab and the electrode. For example, each sub-folded sheet surface has one row of grooves with uniform spacing. Alternatively, each sub-folded sheet surface has two rows of grooves with uniform spacing. The two rows of grooves can be staggered or evenly arranged.

[0050] The materials of the tabs include, but are not limited to, aluminum, copper, nickel, nickel-plated copper, silver, and copper-lithium composite strips.

[0051] In some embodiments, the tabs are 0.2cm-10cm long, 0.2cm-5cm wide, and 4μm-100μm thick.

[0052] In some embodiments, the width of the sub-folded piece is 0.01~3cm, for example, 0.01cm, 0.05cm, 0.1cm, 0.5cm, 1cm, 2cm, 3cm, or any range of two of the above values.

[0053] In some embodiments, the depth of the groove is 0.2 to 10 μm. For example, 0.2 μm, 0.5 μm, 1 μm, 3 μm, 6 μm, 10 μm, or any range between the two.

[0054] The shape of the cross-section of the groove (the cross-section in the thickness direction, i.e., the area of ​​the groove opening) can be any one of parallelogram, trapezoid, circle, arc, and irregular shape.

[0055] In the transverse direction, the spacing between adjacent grooves is 0.5 to 100 times the maximum transverse width of the groove. Preferably, the spacing between adjacent grooves is 1 to 10 times the maximum transverse width of the groove. Within the range of 1 to 10 times, the transverse distribution of grooves is more uniform and moderate, neither too dense nor too sparse, resulting in a better improvement in the lifespan of the tab.

[0056] In the longitudinal direction, the spacing between adjacent grooves is 0.5 to 40 times the maximum longitudinal length of the groove. Preferably, the spacing between adjacent grooves is 1 to 10 times the maximum longitudinal length of the groove. Within the range of 1 to 10 times, the longitudinal distribution of grooves is more uniform and moderate, neither too dense nor too sparse, thus improving the lifespan of the tab.

[0057] The grooves can be located on one surface of the electrode or distributed on both surfaces of the electrode.

[0058] The folding process of the aforementioned electrode structure can be carried out in various ways, including but not limited to one-time molding (using a special mold to directly press out the corresponding shape) and step-by-step bending. The folding process can be carried out at the stage where the current collector is not coated with electrode sheets, during coating, after coating, or after it has been assembled into a battery cell.

[0059] Methods for creating grooves include, but are not limited to, laser cutting, mechanical milling, chemical etching, and physical hot pressing.

[0060] This application provides a battery cell, which includes a positive electrode, a negative electrode, and an electrolyte, wherein the negative electrode or the positive electrode is welded with the aforementioned tabs.

[0061] There are no restrictions on the preparation methods of the positive and negative electrodes; they can be prepared using either dry or wet electrode processes.

[0062] This application also provides a solid-state battery, which includes a plurality of the above-described cells, wherein the electrolyte in the cells is a solid electrolyte.

[0063] Specifically, the positive electrode active material (or negative electrode active material), solid electrolyte, conductive agent, and binder are mixed evenly using a wet or dry method, and then coated onto at least one side of the positive electrode current collector (or negative electrode current collector). After drying (e.g., oven drying), a densification treatment (e.g., rolling) is performed to obtain a composite positive electrode sheet (or composite negative electrode sheet). The composite positive electrode sheet, solid electrolyte layer, and composite negative electrode sheet are then arranged in an orderly manner to obtain the electrode core. At the positive and negative electrode portions of the electrode core, optimized tabs are connected to the tab connecting pieces using a suitable welding process (e.g., laser welding, resistance welding, or ultrasonic welding) to ensure good electrical contact of the battery. After the electrode core is placed in the outer casing (casing), it undergoes isostatic pressing treatment. The isostatic pressing pressure can be 200~600MPa, within which the electrode particles can make close contact, and short circuits at the electrode edges are minimal. Formation and capacity testing are then performed to obtain a solid-state battery.

[0064] This application provides a battery assembly comprising at least two solid-state batteries as described above.

[0065] This application provides an electrical device, including the above-mentioned solid-state battery or battery module, wherein the solid-state battery or battery module serves as the power supply for the electrical device.

[0066] The aforementioned electrical equipment may include at least one of electric vehicles, portable electronic devices, wearable devices, household appliances, and industrial equipment.

[0067] Specifically, electric vehicles may include at least one of electric cars, electric bicycles, and electric scooters; portable electronic devices may include at least one of smartphones, laptops, and tablets; wearable devices may include at least one of smartwatches and fitness trackers; home appliances may include at least one of robotic vacuum cleaners and portable audio equipment; and industrial equipment may include drones.

[0068] The present invention will be further described below through specific embodiments and comparative examples. Unless otherwise specified, the reagents, materials and instruments used below are all conventional reagents, materials and instruments, all of which are commercially available, and the reagents and materials involved can also be synthesized by conventional synthetic methods.

[0069] Example 1

[0070] Positive electrode formulation: NMC811:Li6PS5Cl:VGCF:PTFE=81:15:3:1;

[0071] Anode formulation: Si:SEBS:VGCF=94:4:2;

[0072] Positive current collector (aluminum foil) thickness: 13μm;

[0073] Negative electrode current collector (copper foil) thickness: 9μm;

[0074] Positive electrode dimensions: 95mm × 277mm;

[0075] Negative electrode dimensions: 98mm × 280mm;

[0076] Positive electrode tab dimensions: 25mm × 30mm × 10μm;

[0077] Negative electrode tab dimensions: 25mm×30mm×6μm.

[0078] The positive electrode tab is left untreated. The negative electrode tab is folded longitudinally and has staggered grooves cut laterally: the fold width is 2mm, the number of folds is 10, and the included angle between the two sub-folds is 120°; the size of the cuboid groove is 1mm×0.5mm, the groove depth is 2μm, the longitudinal spacing of the grooves is 2mm, the lateral spacing of the grooves is 2mm, the number of grooves in the longitudinal direction is 10, the number of grooves in the lateral direction is 10, and the grooves are aligned in each row in the longitudinal direction, with a staggered distance of 1mm between the two rows.

[0079] Example 2

[0080] Positive electrode formulation: NMC811:Li6PS5Cl:VGCF:PTFE=81:15:3:1;

[0081] Anode formulation: Si:SEBS:VGCF=94:4:2;

[0082] Positive current collector (aluminum foil) thickness: 13μm;

[0083] Negative electrode current collector (copper foil) thickness: 9μm;

[0084] Positive electrode dimensions: 95mm × 277mm;

[0085] Negative electrode dimensions: 98mm × 280mm;

[0086] Positive electrode tab dimensions: 25mm × 30mm × 10μm;

[0087] Negative electrode tab dimensions: 25mm×30mm×6μm.

[0088] The positive electrode tab is left untreated. The negative electrode tab is folded longitudinally and grooved laterally: the fold width is 2mm, the number of folds is 10, and the included angle between the two sub-folded pieces is 120°; the size of the cuboid groove is 1mm×0.5mm, the groove depth is 2μm, the longitudinal spacing of the groove is 2mm, the lateral spacing of the groove is 2mm, the number of grooves in the longitudinal row is 10, the number of grooves in the lateral row is 10, and the grooves are aligned in each row in the longitudinal direction.

[0089] Example 3

[0090] Positive electrode formulation: NMC811:Li6PS5Cl:VGCF:PTFE=81:15:3:1;

[0091] Anode formulation: Si:SEBS:VGCF=94:4:2;

[0092] Positive current collector (aluminum foil) thickness: 13μm;

[0093] Negative electrode current collector (copper foil) thickness: 9μm;

[0094] Positive electrode dimensions: 95mm × 277mm;

[0095] Negative electrode dimensions: 98mm × 280mm;

[0096] Positive electrode tab dimensions: 25mm × 30mm × 10μm;

[0097] Negative electrode tab dimensions: 25mm×30mm×6μm.

[0098] The positive electrode tab is left untreated. The negative electrode tab is folded longitudinally and has staggered grooves cut laterally: the fold width is 1mm, the number of folds is 20, and the included angle between two sub-folds is 60°; the size of the cuboid groove is 1mm×0.5mm, the depth is 4μm, the longitudinal spacing of the grooves is 1mm, the lateral spacing of the grooves is 1mm, the number of longitudinal rows of grooves is 20, the number of lateral grooves is 20, the grooves are aligned in each row in the longitudinal direction, and the distance between two rows is staggered by 0.5mm.

[0099] Comparative Example 1

[0100] Positive electrode formulation: NMC811:Li6PS5Cl:VGCF:PTFE=81:15:3:1;

[0101] Anode formulation: Si:SEBS:VGCF=94:4:2;

[0102] Positive current collector (aluminum foil) thickness: 13μm;

[0103] Negative electrode current collector (copper foil) thickness: 9μm;

[0104] Positive electrode dimensions: 95mm × 277mm;

[0105] Negative electrode dimensions: 98mm × 280mm;

[0106] Positive electrode tab dimensions: 25mm × 30mm × 10μm;

[0107] Negative electrode tab dimensions: 25mm×30mm×6μm.

[0108] The positive electrode tab is left untreated. The negative electrode tab is left untreated.

[0109] Comparative Example 2

[0110] Positive electrode formulation: NMC811:Li6PS5Cl:VGCF:PTFE=81:15:3:1;

[0111] Anode formulation: Si:SEBS:VGCF=94:4:2;

[0112] Positive current collector (aluminum foil) thickness: 13μm;

[0113] Negative electrode current collector (copper foil) thickness: 9μm;

[0114] Positive electrode dimensions: 95mm × 277mm;

[0115] Negative electrode dimensions: 98mm × 280mm;

[0116] Positive electrode tab dimensions: 25mm × 30mm × 10μm;

[0117] Negative electrode tab dimensions: 25mm×30mm×6μm.

[0118] The positive electrode tab is left untreated. The negative electrode tab is folded only longitudinally. The fold width is 2mm, the number of folds is 10, and the angle between the two sub-folds is 120°.

[0119] Comparative Example 3

[0120] Positive electrode formulation: NMC811:Li6PS5Cl:VGCF:PTFE=81:15:3:1;

[0121] Anode formulation: Si:SEBS:VGCF=94:4:2;

[0122] Positive current collector (aluminum foil) thickness: 13μm;

[0123] Negative electrode current collector (copper foil) thickness: 9μm;

[0124] Positive electrode dimensions: 95mm × 277mm;

[0125] Negative electrode dimensions: 98mm × 280mm;

[0126] Positive electrode tab dimensions: 25mm × 30mm × 10μm;

[0127] Negative electrode tab dimensions: 25mm×30mm×6μm.

[0128] The positive electrode tab is left untreated. The negative electrode tab is simply grooved laterally. The rectangular groove is 1mm × 0.5mm in size and 2μm in depth. The grooves are spaced 2mm apart vertically and 2mm apart horizontally. There are 10 rows of grooves vertically and 10 grooves horizontally. The grooves are aligned vertically in each row.

[0129] Test case

[0130] The negative electrode tabs of the above embodiments and comparative examples are soldered onto the negative electrode sheet using the same process, and assembled into a battery cell using the same packaging process. Specifically, 10 positive electrode sheets and 11 negative electrode sheets are stacked, with all positive electrodes being double-sided. The two outermost negative electrode sheets of the battery cell are single-sided, and the remaining negative electrodes are also double-sided. The positive electrode surface capacity is 3.8 mAh / cm³. 2 The cell capacity is 20Ah. After stacking, tab connectors are soldered to the positive and negative terminals of the cell. After encapsulation with aluminum-plastic film, isostatic testing (conditions: 500Mpa, 420s) is performed to test the capacity, and then the cell can be subjected to subsequent performance tests.

[0131] Cyclic performance testing involved cycling the cells of each embodiment and comparative example at 60°C with a charge / discharge rate of 1C and a voltage range of 2.5-4.2V to test the change in capacity retention during the cycling process.

[0132] Plot the capacity retention rates of Example 1 and Comparative Example 1. Figure 2 The capacity retention rate variation graphs for Embodiment 1 and Comparative Example 1 provided in this application are referenced. Figure 2 In Comparative Example 1, the cell capacity experienced a sharp drop after approximately 205 cycles due to tab breakage. However, Example 1, under the same conditions, could stably cycle up to 335 cycles. Example 1 maintained a capacity retention of 83% at 300 cycles. These results clearly demonstrate that optimizing the tab structure can effectively prevent a sharp drop in cell capacity caused by tab breakage.

[0133] Table 1. Cyclic performance of each embodiment and comparative example

[0134]

[0135] Based on the data in Table 1, Example 1, with its laterally staggered groove design, exhibits superior cycle performance compared to Example 2. While Comparative Example 2, through longitudinal folding alone, improves cycle performance, it still falls short of Example 1. Comparative Example 3, with its laterally grooved design, experiences a sharp drop in cycle count at 275 revolutions. Although this represents a slight improvement in cycle performance compared to Comparative Example 1, it is still inferior to Example 1.

[0136] In summary, the longitudinal folding structure, through its elastic deformation characteristics, dynamically adapts to the longitudinal volume changes of the electrode material during charging and discharging (such as the alloying reaction of silicon-based anodes), dispersing the stress originally concentrated at the end of the tab to the entire folded area, thus avoiding fracture caused by localized stress concentration. The transverse groove structure, through its localized recessed design, forms a stress release path, allowing the transverse shear force to gradually disperse at the edge of the groove, rather than concentrating at a single location. Furthermore, the increased surface area of ​​the groove promotes rapid heat dissipation and suppresses the accumulation of thermal strain. With the combined effect of these two factors, the tab maintains structural integrity during long-term cycling, significantly reducing the risk of open circuits due to fracture, while simultaneously improving the cycle life and thermal stability of the battery cell.

[0137] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A battery tab, characterized in that, The tab has a longitudinal folding structure with ≥2 folds. The longitudinal direction is perpendicular to the boundary between the tab and the electrode plate. The longitudinal folding structure is used to absorb the longitudinal stress generated by the expansion of the electrode material. Folding produces multiple sub-folded pieces, each of which has a groove on its surface to absorb lateral stress generated by the expansion of the electrode material.

2. The electrode tab according to claim 1, characterized in that, The sum of the opening areas of all the grooves of the electrode tab accounts for 0.1% to 50% of the surface area of ​​the electrode tab.

3. The electrode tab according to claim 1, characterized in that, The depth of the groove is 0.1% to 50% of the thickness of the electrode tab.

4. The electrode tab according to any one of claims 1-3, characterized in that, The grooves of at least two adjacent sub-folds are arranged in a staggered pattern.

5. The electrode tab according to any one of claims 1-3, characterized in that, The width of the sub-folded piece is 0.01~3cm, and / or the depth of the groove is 0.2~10μm.

6. The electrode tab according to any one of claims 1-3, characterized in that, On the surface of the sub-folded sheet, grooves are arranged laterally, and the lateral direction is parallel to the boundary between the tab and the electrode sheet.

7. The electrode tab according to claim 3, characterized in that, In the horizontal direction, the spacing between adjacent grooves is 0.5 to 100 times the maximum horizontal width of the groove; And / or, in the longitudinal direction, the spacing between adjacent grooves is 0.5 to 40 times the maximum longitudinal length of the groove.

8. The electrode tab according to any one of claims 1-3, characterized in that, The angle between adjacent sub-folds is 10~170°.

9. A battery cell, characterized in that, The battery cell includes a positive electrode, a negative electrode, and an electrolyte, wherein the negative electrode or the positive electrode is welded with the tab as described in any one of claims 1-8.

10. A solid-state battery, characterized in that, The solid-state battery includes the cell described in claim 9.

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