Tab, tab sheet and battery

Abstract

The application provides a tab, comprising: a tab body, the tab body comprising a welding area and an electrical lead-out area connected to each other, the welding area being used for welding with a tab; the electrical lead-out area being used for electrical lead-out of the tab, a strip-shaped through hole being formed on the electrical lead-out area in a direction from the welding area to the electrical lead-out area, and the electrical lead-out area being divided into tab units in parallel by the strip-shaped through hole; the original single-tab structure is optimized into a parallel multi-tab unit structure in the application, when the battery suffers external impact such as falling or vibration, the impact load originally borne by the single tab is shunted to the multi-tab units, which greatly relieves the stress concentration phenomenon of the tab root; on the other hand, when one of the tab units is accidentally broken due to extreme external force, the other tab units can still maintain complete electrical connection to maintain normal work of the battery cell, thereby significantly reducing the risk of open circuit or internal short circuit and greatly improving the safety and reliability of the battery cell.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a tab, an electrode sheet, and a battery. Background Technology

[0002] As portable electronic devices such as smartphones become thinner, lighter, larger, and more powerful, their core components—soft-pack lithium-ion cells—face increasingly stringent challenges to mechanical reliability. Drop testing is one of the key indicators for measuring the mechanical strength of the cell. To ensure that the cell retains its structural integrity and normal function after an accidental drop, current technologies typically employ a method of folding the tabs inside the core (i.e., "folding the tabs"), attempting to mitigate external impact by altering the physical shape of the tabs.

[0003] However, as end customers increasingly demand higher drop test standards, traditional simple tab folding technology is gradually becoming insufficient to meet these stringent testing requirements. For example... Figure 1-4 As shown in the results, actual tests revealed that after repeated drop impacts, the battery cell tabs often exhibited failure phenomena such as breakage and tearing, leading to open circuits or performance degradation. The reason for this lies in the significant mechanical defects of conventional tab folding methods: firstly, the base of the tab, as the main area of ​​stress concentration, bears a huge bending moment during a drop, making it highly susceptible to metal fatigue tearing; secondly, the lack of effective buffering and current diversion mechanisms for individual tabs or tab assemblies under stress results in excessive stress at a single point, leading to detachment or breakage of the weld between the tab and the current collector. Therefore, overcoming these technical problems and defects is a key issue that needs to be addressed. Summary of the Invention

[0004] To address the technical problem that existing mobile phone soft-pack battery cells fail when subjected to high-standard drop tests, due to stress concentration and tearing at the base of the tabs caused by conventional tab folding methods, and excessive force on a single tab leading to desoldering or breakage of the welding point, thus causing cell failure, this invention provides a tab, a electrode sheet, and a battery.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: The first aspect of the present invention provides an electrode tab, comprising: an electrode tab body, the electrode tab body including a welding region and an electrical lead-out region connected to each other; the welding region is used for welding with an electrode sheet; the electrical lead-out region is used for electrical lead-out of the electrode tab, and a strip-shaped through hole is formed on the electrical lead-out region along the direction from the welding region to the electrical lead-out region, the strip-shaped through hole dividing the electrical lead-out region into parallel electrode tab units.

[0006] Optionally, at least one of the tab units is provided with a buffer section, and the cross-sectional shape of the buffer section is at least one of wavy or pleated.

[0007] Optionally, the length of the tab unit is L1 mm, the length of the electrical lead-out area is L2 mm, and L1 and L2 satisfy the relationship: 0.3≤L1 / L2≤0.9.

[0008] Optionally, along the width direction of the electrode body, a plurality of strip-shaped through holes are provided at intervals on the electrical lead-out area.

[0009] Optionally, the number of strip-shaped through holes provided on each of the electrical lead-out areas is n, and the value of n is in the range of 1≤n≤2.

[0010] Optionally, at least two of the tab units have equal widths; and / or, at least two of the tab units have equal lengths; and / or, the spacing between two adjacent tab units is equal.

[0011] Optionally, the surface of the electrical lead-out area is provided with an insulating adhesive layer, and the electrical lead-out area has the strip-shaped through hole on at least one side of the insulating adhesive layer.

[0012] Optionally, the electrical lead-out area has strip-shaped through holes on both sides of the insulating adhesive layer, and the lengths of the tab units on both sides of the insulating adhesive layer are the same along the length direction of the tab unit.

[0013] A second aspect of the present invention provides an electrode sheet, comprising a current collector and the aforementioned electrode tab, wherein the welding area of ​​the electrode tab is welded to the current collector.

[0014] A third aspect of the present invention provides a battery comprising, as described above, an electrode, a separator, and an electrolyte, wherein the electrode comprises a positive electrode and / or a negative electrode.

[0015] According to the tabs provided by the present invention, by opening strip-shaped through holes in the electrical lead-out area of ​​the tab, the original single tab structure is optimized into a multi-tab unit structure with parallel arrangement. On the one hand, when the battery is subjected to external impacts such as drops or vibrations, the impact load originally borne by a single tab is effectively diverted to two tab units (the stress borne by each tab is reduced to 50% of the total). This greatly alleviates the stress concentration phenomenon at the root of the tab, and the overall impact resistance is improved by nearly 100%, effectively avoiding the problem of bending and tearing at the root of the tab caused by high-standard drop tests. On the other hand, the multi-tab unit structure forms a parallel redundant conductive circuit. When one tab unit fails due to an accidental breakage caused by extreme external force, the other tab units can still maintain complete electrical connection to maintain the normal operation of the cell, thereby significantly reducing the risk of open circuit or internal short circuit and greatly improving the safety and reliability of the cell. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of a battery cell before it falls, provided by existing technology. Figure 2 This is a schematic diagram of a battery cell after it has been dropped, based on existing technology. Figure 3 This is a schematic diagram of the structure of the electrode and electrode tab provided by existing technology; Figure 4 This is a side view structural diagram of the electrode and electrode tab provided by existing technology; Figure 5 This is a schematic diagram of the structure of the electrode sheet and electrode tab provided in an embodiment of the present invention; Figure 6 This is a side view of the electrode sheet and electrode tab provided in an embodiment of the present invention; Figure 7 This is a schematic diagram of the structure of the electrode sheet and electrode tab provided in another embodiment of the present invention; Figure 8 This is a side view of the electrode sheet and electrode tab provided in another embodiment of the present invention; The reference numerals in the accompanying drawings are as follows: 1-Electrical tab body; 11-Welding area; 12-Electrical lead-out area; 121-Strip through hole; 122-Electrical tab unit; 123-Buffer section; 2-Insulating adhesive layer; 100-Electrical tab; 200-Electrical sheet; 201-Positive electrode sheet; 202-Negative electrode sheet; 300-Battery casing. Detailed Implementation

[0018] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0019] In the description of this invention, it should be understood that the terms "longitudinal," "radial," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0020] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0021] like Figures 5-6 As shown, in one embodiment, the first aspect of the present invention provides an electrode tab, comprising: an electrode tab body 1, the electrode tab body 1 including a welding region 11 and an electrical lead-out region 12 connected to each other, the welding region 11 being used for welding with an electrode sheet 200; the electrical lead-out region 12 being used for electrical lead-out of the electrode tab 100, and a strip-shaped through hole 121 being formed on the electrical lead-out region 12 along the direction from the welding region 11 to the electrical lead-out region 12, the strip-shaped through hole 121 dividing the electrical lead-out region 12 into parallel electrode tab units 122.

[0022] This invention optimizes the original single-tab body 1 structure into a multi-tab unit 122 structure by opening a strip-shaped through hole 121 in the electrical lead-out area 12 of the tab body 1. On the one hand, when the battery is subjected to external impacts such as drops or vibrations, the impact load originally borne by a single tab body 1 is effectively diverted to two tab units 122 (the stress borne by each tab is reduced to 50% of the total). This greatly alleviates the stress concentration phenomenon at the root of the tab body 1, and improves the overall impact resistance by nearly 100%, effectively avoiding the problem of bending and tearing at the root of the tab body 1 caused by high-standard drop tests. On the other hand, the multi-tab unit 122 structure forms a parallel redundant conductive circuit. When one tab unit 122 fails due to an unexpected breakage caused by extreme external force, the other tab units 122 can still maintain a complete electrical connection to maintain the normal operation of the cell, thereby significantly reducing the risk of open circuit or internal short circuit and greatly improving the safety and reliability of the cell.

[0023] like Figures 7-8 As shown, in one embodiment, at least one tab unit 122 is provided with a buffer section 123, and the cross-sectional shape of the buffer section 123 is at least one of wavy or pleated.

[0024] This invention forms a spring-like flexible buffer structure by providing a wave-shaped or pleated buffer section 123 on at least one tab unit 122. On the one hand, the buffer section 123 can effectively absorb the impact energy generated by drops or vibrations through its own elastic deformation, thereby blocking or weakening the transmission of impact load to the root of the tab body 1. On the other hand, combined with stress calculation and analysis, the wave-shaped structure further reduces the stress borne by a single tab unit 122 to 15%~25% of the impact force. Compared with the structure that only has a strip-shaped through hole 121, the overall impact resistance of the tab body 1 is improved by nearly 300%. In summary, this design, based on the strip-shaped through hole 121 to evenly distribute the load, further dissipates energy by utilizing corrugated deformation, significantly reduces the bending stress at the root of the tab body 1, significantly improves the buffer capacity and fracture resistance of the tab body 1, and ensures the reliability of the battery cell under harsh operating conditions.

[0025] like Figures 5-6 As shown, in one embodiment, the length of the tab unit 122 is L1 mm, the length of the electrical lead-out region 12 is L2 mm, and L1 and L2 satisfy the relationship: 0.3≤L1 / L2≤0.9.

[0026] Specifically, the value of L1 / L2 is any one value or a range of any two values ​​from 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85 or 0.9; in a preferred embodiment, the value of L1 / L2 is / 0.5-0.75.

[0027] When the value of L1 / L2 is between 0.3 and 0.9, the tab unit 122 achieves a balance between its deformation buffering capacity and welding conductivity, while also exhibiting excellent tear resistance, lithium plating prevention, and high assembly stability. When the value of L1 / L2 is less than 0.3, the tab unit 122 is too short, and the stress buffering effect of the strip-shaped through-hole 121 cannot be fully utilized. The impact load is directly concentrated in the welding area 11, resulting in poor impact resistance of the tab unit 122 and a tendency for the weld area to detach and for the root of the tab unit 122 to tear. When the value of L1 / L2 is greater than 0.9, the tab unit 122 is too long, resulting in an excessively long cantilever section. The root of the strip-shaped through-hole 121 becomes a stress concentration point, which is prone to cracking or even breakage under bending and impact conditions. The impact and tear resistance of the tab unit 122 is significantly reduced. At the same time, the excessively long cantilever also increases the risk of the tab unit 122 scraping against the diaphragm and causing internal short circuits.

[0028] like Figures 5-6As shown, in one embodiment, at least one electrical lead-out area 12 is provided with a plurality of strip-shaped through holes 121 at intervals along the width direction of the tab body 1.

[0029] By opening multiple sets of spaced strip-shaped through holes 121 along the width direction in the electrical lead-out area 12, the electrical lead-out area 12 can be divided into multiple independent tab units 122. During the process of cell drop, impact and cyclic expansion and contraction, the external load can be evenly distributed to different tab units 122 through each strip-shaped through hole 121, avoiding stress concentration at a single point and significantly improving the impact resistance of the tab. At the same time, multiple sets of strip-shaped through holes 121 can form multiple stress release nodes, greatly reducing fatigue damage when the tab is repeatedly bent, effectively improving the bending resistance and tear resistance of the tab, reducing the risk of tab breakage and desoldering, and improving the overall structural reliability of the cell.

[0030] Furthermore, the multiple sets of strip-shaped through holes 121 are evenly distributed along the width direction, which can optimize the adhesion between the tab unit 122 and the insulating adhesive layer 2, reduce the heat sealing stress during the packaging process, and reduce the risk of leakage and short circuit caused by poor heat sealing. At the same time, the segmented tab unit 122 can reduce the local current density of the current conduction path, reduce the local temperature rise during high-rate charging and discharging, and improve the safety performance and cycle life of the battery cell.

[0031] like Figures 5-6 As shown, in one embodiment, the number of strip-shaped through holes 121 provided on each electrical lead-out area 12 is n, and the value of n is in the range of 1≤n≤2.

[0032] Specifically, n can be any value between 1 and 2, or a range of values ​​consisting of any two points; in a preferred embodiment, n is 1.

[0033] When n is between 1 and 2, the number of strip-shaped through holes 121 is moderate, which can evenly distribute the impact and bending stress to multiple tab units 122, avoiding stress concentration and maintaining the structural rigidity of a single tab unit 122, achieving an optimal balance between impact resistance, bending resistance, and tear resistance. When n is 0, stress concentration occurs at the root of the tab when the battery is subjected to external impacts such as drops or vibrations, resulting in poor impact and tear resistance. Moreover, when the tab fails due to accidental breakage caused by extreme external forces, the cell cannot maintain normal operation. When n is greater than 2, the number of strip-shaped through holes 121 on a single electrical lead-out area 12 is too large, resulting in a narrow width and insufficient rigidity of the segmented single tab unit 122. The swing amplitude of the tab unit 122 increases during cell assembly and drops, which exacerbates local stress concentration. Furthermore, the edges of too many strip-shaped through holes 121 are prone to scratching the aluminum-plastic film during packaging, increasing the risk of damage and leakage, ultimately leading to a decrease in the overall reliability of the cell.

[0034] like Figures 5-6As shown, in one embodiment, at least two tab units 122 have equal widths, ensuring that each tab unit 122 has an equal load-bearing cross-section in its physical structure. When the battery cell is subjected to external impact or drop, the equal width design allows each tab unit 122 to evenly distribute the load, avoiding uneven stress distribution caused by width differences.

[0035] like Figures 5-6 As shown, in one embodiment, at least two tab units 122 are of equal length, so that each tab unit 122 has the same lever arm length when deformed under force. The consistent length ensures that the deformation of each tab unit 122 is synchronized when subjected to bending moment, preventing the long tab unit 122 from generating excessive deflection due to different lengths and touching the surrounding components first to cause a short circuit, or the short tab unit 122 from bearing excessive shear force.

[0036] like Figures 5-6 As shown, in one embodiment, the spacing between two adjacent tab units 122 is equal; the equal spacing design eliminates the eccentric moment that may be caused by uneven spacing, ensures that the impact load can be symmetrically transmitted along the center line of the tab, effectively prevents the tab from twisting or bending laterally when under force, and realizes the symmetry and uniformity of stress distribution on the tab body 1.

[0037] like Figures 5-8 As shown, in one embodiment, the surface of the electrical lead-out area 12 is provided with an insulating adhesive layer 2, and the electrical lead-out area 12 has a strip-shaped through hole 121 on at least one side of the insulating adhesive layer 2.

[0038] Specifically, this invention constructs a composite structure with both stress buffering and insulation protection functions by providing an insulating adhesive layer 2 on the surface of the electrical lead-out area 12 and opening a strip-shaped through-hole 121 on at least one side of the insulating adhesive layer 2. The introduction of the strip-shaped through-hole 121 effectively divides the continuous metal cross-section of the electrical lead-out area 12. When the tab 100 is subjected to external impact or bending, the edge of the strip-shaped through-hole 121 can serve as a stress release point, avoiding excessive stress concentration at a single location, thereby significantly reducing the risk of tearing at the root of the tab. At the same time, the synergistic arrangement of the strip-shaped through-hole 121 and the insulating adhesive layer 2 enhances the bonding and anchoring effect between the insulating adhesive layer 2 and the tab body 1, preventing the insulating adhesive layer 2 from peeling or shifting under drop or vibration conditions, ensuring the durable reliability of the insulation protection.

[0039] like Figures 5-8 As shown, in one embodiment, the electrical lead-out area 12 has strip-shaped through holes 121 on both sides of the insulating adhesive layer 2, and the lengths of the tab units 122 on both sides of the insulating adhesive layer 2 are the same along the length direction of the tab unit 122.

[0040] Specifically, when the tab body 1 is subjected to external tensile force or drop impact, the vertical arrangement of the insulating layer 2 and the consistent length of the tab units 122 on both sides ensure that the stress is uniformly transmitted perpendicularly to the edge of the insulating layer 2, avoiding tab twisting or unilateral stress concentration caused by uneven force distribution, thus effectively preventing the risk of tearing at the junction of the insulating layer 2 and the tab. Secondly, the tab units 122 of equal length on both sides have the same lever arm and deformation tendency when subjected to impact, and can undergo elastic or plastic deformation simultaneously. This cooperative deformation mechanism allows the tab units 122 on both sides of the insulating layer 2 to share the load, maximizing the impact resistance advantage of the multi-tab parallel structure.

[0041] like Figures 5-8 As shown, in one embodiment, the second aspect of the present invention provides an electrode 200, including a current collector and the aforementioned electrode tab, wherein the welding area 11 of the electrode tab is welded to the current collector.

[0042] By welding the aforementioned tabs with the slotted through-hole 121 and buffer structure to the current collector, the overall reliability of the electrode 200 assembly is effectively improved. This structure utilizes the current shunting and energy absorption characteristics of the tab unit 122 to significantly reduce stress concentration at the weld between the tab and the current collector when subjected to drops or vibrations, preventing solder joint tearing or tab root breakage, thereby ensuring the mechanical strength of the connection between the electrode 200 and the external circuit.

[0043] In one embodiment, a third aspect of the present invention provides a battery comprising an electrode 200, a separator, and an electrolyte as described above, wherein the electrode 200 comprises a positive electrode 201 and / or a negative electrode 202.

[0044] In one embodiment, the positive electrode 201 includes a positive current collector and a positive active layer coated on the surface of the current collector. The positive active material can be selected from at least one of lithium cobalt oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide (NCM), lithium nickel cobalt aluminum oxide (NCA), and lithium iron phosphate (LFP). By using a highly stable positive electrode material (such as lithium iron phosphate) or a high-energy-density ternary material, combined with the aforementioned tab body 1, the problem of easy breakage at the root of the tab under high voltage or high-rate charge and discharge is effectively solved, ensuring the stability of the positive current collection capability.

[0045] In one embodiment, the negative electrode 202 includes a negative electrode current collector and a negative electrode active layer coated on the surface of the negative electrode current collector. The negative electrode active material includes artificial graphite, natural graphite, modified graphite, or silicon-carbon composite material. This negative electrode structure, in conjunction with the tab body 1 with a buffer function, can effectively adapt to the volume expansion stress of the silicon-based material during charging and discharging, prevent tab connection failure caused by deformation of the electrode 200, and improve the cycle retention rate of the battery.

[0046] In one embodiment, a separator is disposed between the positive electrode 201 and the negative electrode 202, comprising polyethylene (PE), polypropylene (PP), or a composite multilayer microporous membrane thereof, and its surface may be coated with an inorganic ceramic layer such as alumina. This separator possesses excellent thermal stability and mechanical strength. Combined with the aforementioned tab anti-short-circuit design, a triple safety protection system of "tab-electrode 200-separator" is constructed, greatly reducing the probability of thermal runaway of the battery under the risk of drop or internal short circuit.

[0047] In one embodiment, the electrolyte comprises an organic solvent, a lithium salt (such as lithium hexafluorophosphate), and functional additives. This electrolyte system exhibits a wide electrochemical window and high ionic conductivity, and remains chemically stable under high temperature and high pressure conditions. Its excellent wettability with the aforementioned electrode 200 and tab structure ensures that the internal ion transport channels remain unobstructed even when the tabs undergo minor deformation, thus guaranteeing the battery's charge-discharge performance under extreme conditions.

[0048] The negative electrode 202, positive electrode 201 and separator are assembled into a cell by stacking or winding in the manner of "positive electrode 201-separator-negative electrode 202", electrolyte is injected, and after processes such as formation, aging and capacity testing, the cell is packaged in a battery casing 300 to obtain a battery.

[0049] The beneficial effects of the present invention will be further illustrated below with reference to the embodiments.

[0050] To make the inventive objectives, technical solutions, and beneficial effects of this invention clearer, the invention is further described in detail below with reference to embodiments. However, it should be understood that the embodiments of this invention are merely for illustrative purposes and not for limiting the invention, and the embodiments are not limited to those given in the specification. Materials not specified in the embodiments were prepared under conventional conditions or according to the conditions recommended by the material supplier.

[0051] Furthermore, it should be understood that the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, does not preclude the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, unless otherwise stated. It should also be understood that the combined connection relationship between one or more devices / apparatus mentioned in this invention does not preclude the existence of other devices / apparatus before or after the combined devices / apparatus, or the insertion of other devices / apparatus between these explicitly mentioned devices / apparatus, unless otherwise stated. Moreover, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not for limiting the order of the method steps or limiting the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0052] In the following embodiments, the reagents, materials and instruments used, unless otherwise specified, are commercially available or can be obtained through synthesis methods known in the art.

[0053] Table 1. Design of electrode parameters for Examples 1-9 and Comparative Example 1; Example 1 This embodiment illustrates the tab, electrode sheet, and battery disclosed in this invention; it includes the following operational steps: Preparation of negative electrode: Strip-shaped through holes are made in the electrical lead-out area of ​​the negative electrode tab to form parallel tab units. The shape of the tab unit, the length L1 of the tab unit, the length L2 of the electrical lead-out area, and the value of L1 / L2 are shown in Table 1. The welding area of ​​the negative electrode tab is welded to the end of the negative electrode current collector. The negative electrode active material graphite, conductive agent CNT, and binder SBR are mixed in a ratio of 98:1:1 to prepare a negative electrode slurry. The negative electrode slurry is coated onto the copper foil of the negative electrode current collector on a coating machine. After drying, rolling, die cutting and other processes, the negative electrode sheet is obtained.

[0054] Preparation of positive electrode: Strip-shaped through holes are made in the electrical lead-out area of ​​the positive electrode tab to form parallel tab units. The shape of the tab unit, the length L1 of the tab unit, the length L2 of the electrical lead-out area, and the value of L1 / L2 are shown in Table 1. The welding area of ​​the positive electrode tab is welded to the end of the positive electrode current collector. Lithium cobalt oxide, single-walled carbon nanotubes, conductive carbon black SP, and binder PVDF are mixed in a ratio of 97.3:0.5:1.0:1.2 to prepare a positive electrode slurry. The positive electrode slurry is coated onto the surface of the positive electrode current collector on a coating machine. After drying, rolling, die cutting and other processes, a positive electrode sheet that meets the requirements is obtained.

[0055] Electrolyte preparation: Lithium hexafluorophosphate (LiPF6) was dissolved in a mixed solvent consisting of ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) in a mass ratio of 1:2:1 to obtain an electrolyte with a concentration of 1 mol / L.

[0056] Preparation of the diaphragm: PE porous polymer film is used as the membrane substrate; Battery manufacturing: The positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the positive and negative electrodes to provide isolation. Then, the cells are formed by winding. The cells are placed into a pre-formed battery casing, and the electrolyte is injected into the baked and dried cells. After vacuum sealing, settling, and formation processes, the battery is obtained.

[0057] Examples 2-9 Examples 2-9 illustrate the tabs, electrodes, and batteries disclosed in this invention, and include most of the operating steps in Example 1, except that: Both the positive and negative electrodes use the tab parameters shown in Table 1.

[0058] Comparative Examples 1-4 Comparative Example 1 is used to illustrate the tabs, electrodes, and battery disclosed in this invention, including most of the operating steps in Example 1, except that: The positive and negative electrodes use the tab parameters shown in Table 1.

[0059] Comparative Example 2 is used to illustrate the tab, electrode, and battery disclosed in this invention, and its difference lies in: The positive electrode uses the parameters of the tab shown in Example 1; the negative electrode uses the parameters of the tab shown in Comparative Example 1. Comparative Example 3 is used to illustrate the tab, electrode, and battery disclosed in this invention, and its difference lies in: The negative electrode uses the parameters of the tab shown in Example 1; the positive electrode uses the parameters of the tab shown in Comparative Example 1. Comparative Example 4 is used to illustrate the tab, electrode, and battery disclosed in this invention, and its difference lies in: Only the electrical lead-out areas of the negative and positive electrodes are designed to be wavy; Performance testing The following performance tests were performed on the batteries prepared in Examples 1-9 and Comparative Examples 1-4: 1. Free-fall test: The battery cells are installed in the whole machine and dropped. The drop height is 1.2m. The drop contact surface is a hard cement board. The drop direction is 6 sides in a cycle (front, back, both sides of the long side, both sides of the short side, and the thick side). Each round is 6 times as 1 set, and 200 sets of continuous drops are performed.

[0060] 2. Electrical performance test: Charging: 0.5C constant current to 4.5V, constant voltage cutoff 0.02C; Discharging: 0.5C constant current to 3.0V; single cycle rest for 10min; total number of cycles: 500.

[0061] The test results are shown in Table 2.

[0062] Table 2 Battery Electrochemical Performance Comparing Examples 1-3 and Comparative Examples 1-4, it can be seen that when both the positive and negative electrode tabs have strip-shaped through holes, and the number of through holes (n) is 1-2, the tabs do not break or show significant deformation or desoldering after the drop test; the internal resistance increase is only 1.8%~2.0%, and the capacity retention rate after 500 cycles can reach over 92.2%, exhibiting the best overall electrochemical and mechanical performance. This is because a small number of strip-shaped through holes can release the stress generated by charging, discharging, and drop impacts, reducing stress concentration in the tabs and solder areas, preventing desoldering and tearing, stabilizing the cell's internal resistance, and delaying capacity decay. When both the positive and negative electrode tabs have strip-shaped through holes, and the number of through holes (n) is greater than 2, the tab unit breaks directly after the drop test, the internal resistance increase soars to 7.8%, and the cycle capacity retention rate drops significantly to 82.6%. When the number of through holes is too large, it greatly weakens the overall structural strength of the tab. Under drop impact, the tab is prone to breakage, the conductive path is damaged, the internal resistance increases significantly, and the cycle life is significantly reduced. When neither the positive nor negative electrode tab body has strip-shaped through holes, the tab breaks significantly during drop test, the internal resistance increases by as much as 12.5%, and the capacity retention rate after 500 cycles is only 76.5%, which is the worst performance. Because the non-through-hole structure cannot buffer deformation stress, stress continuously concentrates at the root of the tab and the welding area during drop and cycling, making it extremely prone to fracture failure, resulting in very poor conductivity and the fastest capacity decay. When the tab body of the positive electrode has one strip-shaped through-hole, while the tab body of the negative electrode does not, the positive electrode tab remains intact, but the negative electrode tab experiences a slight fracture, with an internal resistance increase of 9.6% and a cycle capacity retention rate of 80.2%. Due to the lack of a stress-relieving structure in the negative electrode, the negative electrode tab is damaged first under impact, damaging the negative electrode's conductive path, increasing internal resistance, and decreasing cycle performance. When the tab body of the positive electrode does not have a strip-shaped through-hole, while the tab body of the negative electrode has one... With a strip-shaped through-hole, the negative electrode tab remains intact, while the positive electrode tab is slightly broken. The internal resistance increases by 10.4%, and the cycle capacity retention rate is 75.2%. Because the positive electrode lacks a through-hole to buffer stress, the tab is prone to breakage. The lithium insertion / extraction range of the positive electrode active material is greater, and the capacity decay caused by stress damage is more significant than that of the negative electrode. When only the electrical lead-out areas of the negative and positive electrode tabs are designed as wavy without the strip-shaped through-hole, the wave buffer section of the tab can absorb a small amount of impact energy. However, due to the lack of a multi-tab conductive structure formed by the strip-shaped through-hole, the stress concentration problem at the root of the tab and the welding area cannot be fundamentally solved. After multiple drops and long cycles, cracks and solder joints are easily generated, the internal resistance increases significantly, and the cycle capacity decay is severe.

[0063] Comparing Examples 1 and 4-5, it can be seen that when a wave-shaped or pleated buffer section is provided on the tab unit, the tab remains intact without breakage or detachment during drop tests, with internal resistance increases of only 1.8% and 1.9% respectively, and cycle capacity retention exceeding 92%. Because the wave / pleated buffer section has deformation buffering capabilities, it can absorb tensile and compressive stresses from drops and charging / discharging, preventing stress concentration at the welding position, protecting the welding area and the tab body, and maintaining low internal resistance and high cycle capacity retention. When no buffer section is provided on the tab unit, the tab shows slight deformation during drop tests, with internal resistance increasing to 3.5% and capacity retention decreasing to 89.7%. The lack of a buffer structure to share stress means external forces act directly on the entire tab, easily causing plastic deformation, stress accumulation in the welding area, a slight increase in internal resistance, and a reduction in cycle life.

[0064] Comparing Examples 1 and 6-9, it can be seen that when the L1 / L2 ratio is between 0.3 and 0.9, the tab shows no breakage, only slight stress marks or tiny cracks, the internal resistance increases by 1.8% to 3.1%, and the capacity retention rate after 500 cycles is 90.1% to 92.7%. Within this range, the buffer section length matches the overall tab size, resulting in a moderate stress buffering effect. Local stress concentration is not caused by an excessively short or long buffer section, and the tab structure is stable with good overall performance. When the L1 / L2 ratio is less than 0.3, the internal resistance increases by 8.2%, and the capacity retention rate is only... 81.9%; The buffer section length is insufficient, and after the drop test, a large area of ​​the electrode and current collector welding area detached. Due to the small effective deformation space of the buffer section, the impact stress cannot be effectively released, and all the stress is concentrated at the welding interface, causing the welding area to detach and the conductivity to deteriorate significantly; When the value of L1 / L2 is greater than 0.9, obvious cracks appear at the root of the electrode, the internal resistance increases by 6.7%, and the cycle capacity retention rate is 83.3%; The buffer section ratio is too large, and the structural margin at the root of the electrode is insufficient. After being subjected to force, the stress at the root is concentrated and cracked, the mechanical strength of the electrode decreases, the internal resistance increases, and the cycle performance deteriorates significantly.

[0065] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A type of electrode, characterized in that: include: The electrode body includes a welding area and an electrical lead-out area connected to each other. The welding area is used for welding with an electrode sheet. The electrical lead-out area is used for electrical lead-out of the electrode. A strip-shaped through hole is formed on the electrical lead-out area along the direction from the welding area to the electrical lead-out area. The strip-shaped through hole divides the electrical lead-out area into parallel electrode units.

2. The electrode tab according to claim 1, characterized in that: At least one of the tab units is provided with a buffer section, and the cross-sectional shape of the buffer section is at least one of wavy or pleated.

3. The electrode tab according to claim 1, characterized in that: The length of the tab unit is L1 mm, the length of the electrical lead-out area is L2 mm, and L1 and L2 satisfy the relationship: 0.3≤L1 / L2≤0.

9.

4. The electrode tab according to claim 1, characterized in that: Along the width direction of the electrode body, a plurality of strip-shaped through holes are provided at intervals on the electrical lead-out area.

5. The electrode tab according to claim 1, characterized in that: The number of strip-shaped through holes provided on each of the electrical lead-out areas is n, and the value of n is in the range of 1≤n≤2.

6. The electrode tab according to claim 4, characterized in that: At least two of the tab units have equal widths; and / or, at least two of the tab units have equal lengths; and / or, the spacing between two adjacent tab units is equal.

7. The electrode tab according to claim 1, characterized in that: The surface of the electrical lead-out area is provided with an insulating adhesive layer, and the electrical lead-out area has the strip-shaped through hole on at least one side of the insulating adhesive layer.

8. The electrode tab according to claim 7, characterized in that: The electrical lead-out area has strip-shaped through holes on both sides of the insulating adhesive layer, and the lengths of the tab units on both sides of the insulating adhesive layer are the same along the length direction of the tab unit.

9. An electrode sheet, characterized in that: It includes a current collector and a tab as described in any one of claims 1 to 8, wherein the welding area of ​​the tab is welded to the current collector.

10. A battery, characterized in that: Includes the electrode, separator, and electrolyte as described in claim 9, wherein the electrode includes a positive electrode and / or a negative electrode.

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