battery

Abstract

This utility model relates to the field of batteries, specifically to a battery. The battery includes a positive electrode, a negative electrode, and a separator. The positive electrode includes a positive tab, and the negative electrode includes a negative tab, which are located on opposite sides of the battery width. The positive tab extends beyond the separator by a dimension L1 of 6mm-15mm, and the negative tab extends beyond the separator by a dimension L2 of 6mm-15mm. The battery also includes a positive electrode adapter with a first straight portion and a first connecting portion, and a negative electrode adapter with a second straight portion and a second connecting portion. The width of the first straight portion is L3, and the width of the second straight portion is L4, with L1:L3 = 1:(0.4-1.5) and L2:L4 = 1:(0.4-1.5). The welding area between the first straight portion and the positive tab is S1; the welding area between the second straight portion and the negative tab is S2; the area of ​​the first straight portion is S3, and the area of ​​the second straight portion is S4; with S1:S3 = 1:(1.35-3) and S2:S4 = 1:(1.35-3). The battery of this invention has an optimized tab structure, which effectively improves the problem of increased internal resistance after battery vibration.

Description

Technical Field

[0001] This utility model relates to the field of batteries, specifically to a battery. Background Technology

[0002] With the rapid development of the new energy vehicle industry, the electrical performance and safety of power batteries, as core components, are receiving increasing attention. Within a battery, the tab structure is a crucial component connecting the internal active material of the cell to the external circuitry; its design directly impacts the battery's electrical performance, safety, and lifespan.

[0003] Currently, the commonly used electrode structures are mainly of two types: single-sided and double-sided. Traditional single-sided electrode structures are prone to localized overheating under high-current charging and discharging conditions due to the limited electrode area. To solve this problem, the industry has developed a double-sided electrode structure, where the electrodes extend symmetrically on both sides along the width of the cell, forming a full electrode structure. This effectively increases the current-carrying capacity of the positive and negative electrodes and reduces ohmic heat generation within the cell.

[0004] However, the existing all-tab structure design still has some defects, which leads to an increase in internal resistance after battery vibration, seriously affecting the normal use of the battery. Utility Model Content

[0005] The purpose of this invention is to overcome the problems existing in the prior art and provide a battery. The battery of this invention optimizes the electrode structure, effectively improving the problem of increased internal resistance after battery vibration.

[0006] In related technologies, the design flaws of the full-tab structure lead to increased internal resistance after battery vibration, severely affecting normal use. Through extensive research, the inventors discovered that the cause of this problem lies in the fact that in existing tab designs, the full tabs extend from both sides of the battery's width and are welded to the adapter plate, lacking sufficient constraint in the battery's height direction. Therefore, during battery vibration, stress concentration can easily cause the tabs to break or the solder joints to crack, leading to tab connection failure and increased battery internal resistance. Based on this, the inventors of this utility model propose the following solution:

[0007] This utility model provides a battery, including an electrode assembly and a casing; the electrode assembly includes a positive electrode plate, a negative electrode plate, and a separator; the positive electrode plate includes a positive current collector and a positive electrode tab extending from one side of the positive current collector, and the size of the positive electrode tab is the same as the size of the positive current collector in the height direction of the battery; the negative electrode plate includes a negative current collector and a negative electrode tab extending from one side of the negative current collector, and the size of the negative electrode tab is the same as the size of the negative current collector in the height direction of the battery; the positive electrode tab and the negative electrode tab are respectively located on both sides of the width direction of the battery; the casing includes a cover plate and a bottom shell, the bottom shell and the cover plate forming a receiving cavity for accommodating the electrode assembly, the cover plate including a positive electrode post and a negative electrode post; in the width direction, the positive electrode tab extends beyond the separator by a dimension L1 of 6mm-15mm, and the negative electrode tab extends beyond the separator by a dimension L2 of 6mm-15mm; the battery also includes a positive electrode adapter and a negative electrode... The adapter piece includes a first straight portion and a first connecting portion, and a negative adapter piece includes a second straight portion and a second connecting portion. The first straight portion is welded to the positive electrode tab, the first connecting portion is connected to the positive electrode post, the second straight portion is welded to the negative electrode tab, and the second connecting portion is connected to the negative electrode post. The first straight portion has a width dimension of L3, the second straight portion has a width dimension of L4, L1:L3 is 1:(0.4-1.5), and L2:L4 is 1:(0.4-1.5). The welding area between the first straight portion and the positive electrode tab is a first region with an area of ​​S1. The welding area between the second straight portion and the negative electrode tab is a second region with an area of ​​S2. The area of ​​the first straight portion is S3, and the area of ​​the second straight portion is S4. S1:S3 is 1:(1.35-3), and S2:S4 is 1:(1.35-3).

[0008] In one instance, L1:L3 is 1:(0.5-0.98).

[0009] In one instance, L2:L4 is 1:(0.5-0.98).

[0010] In one example, the tensile strength of the positive electrode tab in the width direction is 150 MPa-400 MPa.

[0011] In one example, the tensile strength of the negative electrode tab in the width direction is 300MPa-650MPa.

[0012] In one example, the thickness of the positive electrode tab is 8 μm-25 μm.

[0013] In one example, the thickness of the negative electrode tab is 3μm-15μm.

[0014] In one example, the battery further includes an electrolyte located within the casing; the battery is placed vertically along the height direction, wherein the electrolyte level does not exceed the lower edge of the first region and does not exceed the lower edge of the second region; wherein the lower edge of the first region refers to the edge of the first region away from the cover plate, and the lower edge of the second region refers to the edge of the second region away from the cover plate.

[0015] In one example, along the thickness direction of the battery, the surfaces of the first straight portion welded to the positive electrode tab and the surfaces of the second straight portion welded to the negative electrode tab are staggered.

[0016] In one example, in the thickness direction, the distance between the surface where the first straight portion is welded to the positive electrode tab and the surface where the second straight portion is welded to the negative electrode tab is 0.05mm-0.4mm.

[0017] In one instance, L1-L2 ≤ 5mm.

[0018] In one example, corner adhesive is provided at least two corners of the electrode assembly away from the cover plate; the thickness of the corner adhesive is 0.03mm-0.06mm; the size of the corner adhesive is 10mm-25mm along the width direction; and the size of the corner adhesive is 40mm-60mm along the height direction of the battery.

[0019] In one example, along the height direction of the battery, the distance from the center line of the first region to the upper edge of the first straight portion is less than the distance from the center line of the first region to the lower edge of the first straight portion; wherein, the upper edge of the first straight portion refers to the edge of the first straight portion close to the cover plate, and the lower edge of the first straight portion refers to the edge of the first straight portion away from the cover plate.

[0020] In one example, along the height direction of the battery, the distance from the center line of the second region to the upper edge of the second straight portion is less than the distance from the center line of the second region to the lower edge of the second straight portion; wherein, the upper edge of the second straight portion refers to the edge of the second straight portion closer to the cover plate, and the lower edge of the second straight portion refers to the edge of the second straight portion farther from the cover plate.

[0021] In one example, the battery is placed vertically along the height direction, and the dimension between the horizontal line where the center of the electrode assembly is located and the horizontal line where the center of gravity of the electrode assembly is located is less than or equal to 1 / 6 of the height of the electrode assembly.

[0022] In one example, the electrode assembly includes an arcuate region and a flat region connected to the arcuate region; an insulating adhesive film is provided on the outer surface of the arcuate region located at the first end of the electrode assembly; wherein, the first end of the electrode assembly refers to the end of the electrode assembly close to the cover plate; in the height direction of the battery, the distance from the outer surface of the insulating adhesive film to the inner surface of the cover plate is 2mm-6mm.

[0023] In one example, a first adhesive tape is provided on the outer surface of the first region, and the first adhesive tape at least completely covers the first region.

[0024] In one example, a second adhesive tape is provided on the outer surface of the second region, and the second adhesive tape at least completely covers the second region.

[0025] In one example, in the width direction, the ratio of the size of the first adhesive tape to the dimension L1 of the positive electrode tab extending beyond the diaphragm is 1-3.

[0026] In one example, in the width direction, the ratio of the size of the second adhesive tape to the size L2 of the negative electrode tab extending beyond the diaphragm is 1-3.

[0027] Through the above technical solution, this utility model has at least the following advantages compared with the prior art: The battery of this utility model effectively improves the problem of increased internal resistance after battery vibration, specifically:

[0028] First, the dimensions of L1, L2, L1:L3, and L2:L4 are defined. This ensures that the positive and negative tabs protrude appropriately from the separator, and that the current distribution between the tabs and the adapter plates is more uniform, preventing excessively high local current density. It also reduces the current path length and increases the conductive area, thereby lowering the battery's internal resistance. Furthermore, it avoids stress concentration at the connection points, improving the battery's reliability under mechanical shock and vibration conditions and preventing internal short circuits caused by connection breakage.

[0029] Secondly, by defining S1:S3 and S2:S4, a stable and uniform weld can be formed, reducing welding defects. It can also optimize the mechanical strength and sealing of the battery, preventing cracking or loosening caused by mechanical stress, thereby improving the internal resistance of the battery after vibration.

[0030] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. Attached Figure Description

[0031] Figure 1 The diagram shown is a structural schematic of the electrode assembly in an example of this utility model.

[0032] Figure 2 The diagram shown is a structural schematic of the outer shell in an example of this utility model.

[0033] Figure 3 The diagram shown is a structural schematic of the battery in an example of this utility model.

[0034] Figure 4 The diagram shown is a side view of the battery structure in an example of this utility model.

[0035] Figure 5 The diagram shown is a schematic diagram of the first region and the second region in an embodiment of this utility model.

[0036] Figure label:

[0037] 11-Positive electrode, 21-Negative electrode;

[0038] 3-Outer shell; 31-Cover plate; 32-Bottom shell; 311-Positive terminal; 312-Negative terminal;

[0039] 4-Positive electrode adapter; 41-First straight portion; 42-First connecting portion;

[0040] 5-Negative electrode adapter piece; 51-Second straight part; 52-Second connecting part. Detailed Implementation

[0041] The specific embodiments of this utility model are described in detail below. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of this utility model.

[0042] This utility model provides a battery, including an electrode assembly and a casing. The electrode assembly includes a positive electrode plate, a negative electrode plate, and a separator; the positive electrode plate includes a positive current collector and a positive tab extending from one side of the positive current collector, wherein the size of the positive tab is the same as the size of the positive current collector in the height direction of the battery; the negative electrode plate includes a negative current collector and a negative tab extending from one side of the negative current collector, wherein the size of the negative tab is the same as the size of the negative current collector in the height direction of the battery. The positive tab and the negative tab are respectively located on both sides in the width direction of the battery. Figure 1 The figure shows a schematic diagram of the electrode assembly in an example of this utility model. As can be seen from the figure, the positive electrode tab 11 and the negative electrode tab 12 are located on both sides of the width direction of the battery.

[0043] In this invention, in the width direction, the dimension L1 of the positive electrode tab extending beyond the separator is 6mm-15mm, for example, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, or 15mm. The dimension L2 of the negative electrode tab extending beyond the separator is 6mm-15mm, for example, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, or 15mm. L1 and L2 can be obtained by conventional methods in the art, for example, discharging the battery to 0% SOC, disassembling the battery casing, randomly selecting at least 5 points on one side edge of the battery in the width direction on the positive / negative electrode tabs, measuring the dimension of the positive / negative electrode tab extending beyond the separator at each point, and taking the average value.

[0044] In this invention, the outer casing includes a cover plate and a bottom shell. The bottom shell and the cover plate form a receiving cavity for accommodating the electrode assembly. Figure 2 The diagram shows a schematic representation of the outer casing in an embodiment of this utility model. As can be seen, the outer casing 3 includes a cover plate 31 and a bottom shell 32, which together form a receiving cavity. The cover plate includes a positive electrode post and a negative electrode post. The battery also includes a positive electrode adapter and a negative electrode adapter; the positive electrode adapter includes a first straight portion and a first connecting portion, and the negative electrode adapter includes a second straight portion and a second connecting portion. The first straight portion is welded to the positive electrode tab, the first connecting portion is connected to the positive electrode post, the second straight portion is welded to the negative electrode tab, and the second connecting portion is connected to the negative electrode post. Figure 3 The diagram shown is a structural schematic of a battery according to an embodiment of this utility model, where the bottom shell is not shown. Figure 3 As can be seen, the cover plate 31 includes a positive electrode post 311 and a negative electrode post 312. The battery also includes a positive electrode adapter 4 and a negative electrode adapter 5, wherein the positive electrode adapter 4 includes a first straight portion 41 and a first connecting portion 42, and the negative electrode adapter 5 includes a second straight portion 51 and a second connecting portion 52. The first straight portion 41 is welded to the positive electrode tab, and the first connecting portion 42 is connected to the positive electrode post; the second straight portion 51 is welded to the negative electrode tab, and the second connecting portion 52 is connected to the negative electrode post. Figure 4 The diagram shown is a side view of the battery structure in an example of this utility model.

[0045] In this utility model, the dimension of the first straight portion in the width direction is L3, and the dimension of the second straight portion in the width direction is L4. The ratio of L1 to L3 is 1:(0.4-1.5), for example, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4 or 1:1.5; the ratio of L2 to L4 is 1:(0.4-1.5), for example, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4 or 1:1.5.

[0046] In one instance, L1:L3 is 1:(0.5-0.98).

[0047] In one instance, L2:L4 is 1:(0.5-0.98).

[0048] When L1:L3 and / or L2:L4 are within a suitable range, the current distribution between the tabs and the adapter plate is more uniform, avoiding excessively high local current density. This reduces the current path length and increases the conductive area, thereby lowering the battery's internal resistance. Furthermore, it avoids stress concentration at the connection points, improving battery reliability under mechanical shock and vibration conditions and preventing internal short circuits caused by connection breakage. When L1:L3 and / or L2:L4 are less than 1:1, the current is mainly concentrated in the contact area between the tabs and the adapter plate. The tabs' insufficient extension beyond the separator prevents effective current dispersion. While an excessively wide adapter plate provides a larger conductive area, the insufficient tab extension prevents even current distribution across the entire adapter plate width, increasing both current density and current path length, thus increasing the battery's internal resistance. Additionally, an insufficient tab extension beyond the separator restricts welding space, making it prone to problems like incomplete or missed welds. An excessively wide adapter plate also increases welding difficulty and time, reducing assembly efficiency and increasing production costs. When L1:L3 and / or L2:L4 are greater than 1:0.4, the length of the tabs extending beyond the separator is too large, resulting in insufficient mechanical strength at the connection point with the adapter piece. On the other hand, the width of the adapter piece is too small, making it easy to generate large stress during welding or assembly. This stress is concentrated at the connection point between the tabs and the adapter piece, which is more likely to cause the connection point to break or deform after vibration, increasing the internal resistance of the battery.

[0049] In this invention, the welding area between the first straight portion and the positive electrode tab is a first region, and the area of ​​the first region is S1; the welding area between the second straight portion and the negative electrode tab is a second region, and the area of ​​the second region is S2; the area of ​​the first straight portion is S3, and the area of ​​the second straight portion is S4. S1:S3 is 1:(1.35-3), for example, 1:1.35, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5, 1:2.6, 1:2.7, 1:2.8, 1:2.9, or 1:3. S2:S4 is 1:(1.35-3), for example, 1:1.35, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5, 1:2.6, 1:2.7, 1:2.8, 1:2.9, or 1:3. Figure 5 The diagram shown is a schematic diagram of the first region and the second region in an embodiment of this utility model. The first region and the second region are enclosed in the dashed box in the diagram.

[0050] When S1:S3 and / or S2:S4 are within a specific range, it helps to form a stable and uniform weld, reduces welding defects, optimizes the mechanical strength and sealing of the battery, prevents cracking or loosening caused by mechanical stress, and thus improves the internal resistance of the battery after vibration. When S1:S3 and / or S2:S4 is less than 1:3, the welding area between the tab and the adapter is too small relative to the area of ​​the flat part. An insufficiently small welding area between the tab and the adapter leads to insufficient mechanical strength at the weld point. During battery use, especially under mechanical vibration or impact, the weld point is prone to loosening or even breakage, affecting the structural stability of the battery. An excessively large area of ​​the flat part increases the assembly gap between the adapter and the casing or electrode assembly, causing stress concentration. Over time, stress fatigue may cause cracking or loosening at the connection point, further increasing the battery's internal resistance. When S1:S3 and / or S2:S4 are greater than 1:1.35, the welding area of ​​the tab and the adapter is too large relative to the area of ​​the flat part, which will cause uneven current distribution at the welding point. The current will be mainly concentrated in the smaller area of ​​the flat part, which will easily lead to local overheating and increased resistance. In addition, the excessively large welding area will increase the contact resistance of the welding point, lengthen the path to the welding point, and further increase the internal resistance.

[0051] In this invention, the tensile strength of the positive electrode tab in the width direction is 150MPa-400MPa, for example, 150MPa, 200MPa, 250MPa, 300MPa, 350MPa, or 400MPa. The tensile strength of the negative electrode tab in the width direction is 300MPa-650MPa, for example, 300MPa, 350MPa, 400MPa, 450MPa, 500MPa, 550MPa, or 600MPa. The tensile strength of the positive and negative tabs in the width direction can be tested using conventional methods in the art. For example, the battery is discharged to 0% SOC, the positive / negative electrode is removed from the battery, and a 6mm×6mm positive / negative current collector is cut as a test sample. The thickness and width of the sample are measured using a microscope, thickness gauge, or other tools. The initial cross-sectional area of ​​the sample is calculated. A Mettler Toledo thermomechanical analyzer (TMA / SDTA 2+LF / 1100 / 327) is used to apply a tensile force to the sample until the sample breaks. The force and displacement data during the tensile process are recorded, and a stress-strain curve is generated. The maximum tensile force value of the sample is read from the curve, and the tensile strength is calculated according to the formula "tensile strength = maximum tensile force / initial cross-sectional area".

[0052] In this invention, the thickness of the positive electrode tab is 8μm-25μm, for example, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 21μm, 22μm, 23μm, 24μm, or 25μm. The thickness of the negative electrode tab is 3μm-15μm, for example, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, or 15μm.

[0053] Further research by the inventors revealed that the existing technology lacked precise control over the electrolyte level, resulting in an excessively high electrolyte level that wetted the welding area between the tabs and the adapter. Long-term corrosion of the electrolyte led to decreased conductivity, affecting battery performance and safety. Therefore, the battery of this invention further regulates the relationship between the electrolyte level and the welding area between the tabs and the adapter.

[0054] In this invention, the battery further includes an electrolyte located within the casing. When the battery is placed vertically along its height, the electrolyte level does not exceed the lower edge of either the first or second region. The lower edge of the first region refers to the edge of the first region away from the cover plate, and the lower edge of the second region refers to the edge of the second region away from the cover plate. Whether the electrolyte level exceeds the lower edge of the first or second region can be determined by the following method: after photographing the entire area covering the electrolyte distribution using a high-resolution X-ray detector, the vertical distance between the electrolyte level and the bottom baseline of the first / second region is measured using image analysis software.

[0055] By controlling the electrolyte level to not exceed the bottom of the welding area, chemical corrosion of the solder joint by the electrolyte can be avoided, maintaining the mechanical strength and conductivity of the solder joint. It also maintains the current conduction efficiency at the solder joint, preventing current dispersion or short circuits caused by the presence of electrolyte, and helps reduce resistance in the current path, thereby lowering the battery's internal resistance. However, when the electrolyte level exceeds the bottom of the welding area, the electrolyte directly contacts the welding area. The hydrofluoric acid produced during the decomposition of lithium salts (such as lithium hexafluorophosphate) in the electrolyte reacts with the welding area, causing corrosion of the solder joint material, reducing mechanical bonding strength, leading to poor soldering or short circuits, increasing the battery's internal resistance, and severely reducing battery life.

[0056] Further research by the inventors revealed that factors such as unreasonable tab structure design or improper welding surface setting between the tab and the adapter plate can cause significant shifts in the center and center of gravity when the battery vibrates, exacerbating uneven internal stress distribution, further damaging the welding area, and reducing the battery's lifespan.

[0057] In this invention, along the thickness direction of the battery, the surfaces of the first straight portion welded to the positive electrode tab and the second straight portion welded to the negative electrode tab are staggered. The distance between the surfaces of the first straight portion welded to the positive electrode tab and the surfaces of the second straight portion welded to the negative electrode tab in the thickness direction is 0.05mm-0.4mm, for example, 0.05mm, 0.1mm, 0.2mm, 0.3mm, or 0.4mm.

[0058] By adjusting the distance between the surface where the first straight part is welded to the positive electrode tab and the surface where the second straight part is welded to the negative electrode tab, it is possible not only to disperse the expansion stress of the electrodes during charging and discharging and reduce uneven stress on the casing, thereby improving structural stability and avoiding casing deformation or cracking caused by local stress concentration; it is also possible to ensure that the center of gravity of the electrode assembly is located on the center line of the electrode assembly thickness direction, reducing damage when the battery vibrates.

[0059] In this invention, L1-L2 ≤ 5mm, for example, 5mm, 4mm, 3mm, 2mm, 1mm, or 0.5mm. By adjusting the difference in the size of the positive and negative tabs beyond the separator, it helps to make the mass on both sides similar, further ensuring that the center of gravity of the cell is located on the center line in the thickness direction. This avoids casing deformation or electrode misalignment caused by increased vibration due to center of gravity shift or excessive local stress during external impact, reducing mechanical stress concentration under vibration or external force. In addition, it can also prevent the cell from tilting due to gravity shift, reducing the possibility of short circuits caused by contact between the tabs and other parts such as the cover plate, ensuring battery safety.

[0060] In this invention, along the height direction of the battery, the distance from the center line of the first region to the upper edge of the first straight portion is less than the distance from the center line of the first region to the lower edge of the first straight portion; wherein, the upper edge of the first straight portion refers to the edge of the first straight portion near the cover plate, and the lower edge of the first straight portion refers to the edge of the first straight portion away from the cover plate. Similarly, along the height direction of the battery, the distance from the center line of the second region to the upper edge of the second straight portion is less than the distance from the center line of the second region to the lower edge of the second straight portion; wherein, the upper edge of the second straight portion refers to the edge of the second straight portion near the cover plate, and the lower edge of the second straight portion refers to the edge of the second straight portion away from the cover plate.

[0061] By adjusting the distance between the center line of the first / second region and the upper and lower edges of the straight section, the distance between the first / second region and the bottom of the straight section is made relatively far. After the electrode assembly and the adapter piece are welded into a single structure, the weight near the cover plate is greater than that of the electrode assembly near the bottom of the casing. By adjusting the welding position of the electrode assembly and the adapter piece closer to the cover plate, the shaking amplitude of the battery under external force is reduced, the risk of damage to the electrode tab welding area is reduced, and a larger deformation space is provided for the expansion of the electrode material during charging and discharging, so that the expansion force is evenly distributed to the entire casing, reducing local stress at the bottom and preventing cracks from forming at the bottom due to excessive force.

[0062] In this invention, the battery is placed vertically along the height direction, and the dimension between the horizontal line where the center of the electrode assembly is located and the horizontal line where the center of gravity of the electrode assembly is located along the height direction is less than or equal to 1 / 6 of the height of the electrode assembly.

[0063] By adjusting the relationship between the horizontal line where the center of the electrode assembly is located and the horizontal line where the center of gravity of the electrode assembly is located, it helps to reduce the amplitude of the electrode assembly's sway within the casing when subjected to external forces. This reduces the risk of electrode material loosening or separator damage caused by mechanical stress, avoids the possibility of internal short circuits, and improves the mechanical stability of the battery. In addition, it can also reduce uneven stress distribution caused by battery vibration, which could damage the welding area.

[0064] In this invention, the electrode assembly may include a core formed by stacking and winding the positive electrode, the negative electrode, and the separator, or it may include a stacked core formed by stacking the positive electrode, the negative electrode, and the separator.

[0065] In one example, the electrode assembly includes a winding core.

[0066] In this invention, when the electrode assembly includes a core, the electrode assembly includes an arc-shaped region and a straight region connected to the arc-shaped region. Insulating adhesive paper is provided on the outer surface of the arc-shaped region at the first end of the electrode assembly; wherein, the first end of the electrode assembly refers to the end of the electrode assembly closest to the cover plate. The battery casing is typically made of metal; if the edges of the electrode sheets are exposed, they may come into contact with the casing, causing a short circuit. The insulating adhesive paper, by covering the arc-shaped region, forms an insulating layer, obstructing the current path and preventing short circuits, thus improving battery safety.

[0067] In this invention, the distance from the outer surface of the insulating tape to the inner surface of the cover plate in the height direction of the battery is 2mm-6mm, for example, 2mm, 3mm, 4mm, 5mm, or 6mm. The insulating tape is located at the arc of the electrode assembly near the cover plate, and its outer surface maintains a gap of 2mm-6mm with the cover plate. This ensures that the position of the electrode assembly within the casing will not be significantly shifted due to external forces, effectively reducing the impact of mechanical impact on the internal structure of the battery and enhancing the overall mechanical stability of the battery. At the same time, the fixing effect of the insulating tape ensures the stability of the gap as a heat dissipation channel, allowing the heat inside the battery to be more effectively conducted to the cover plate through this space and ultimately dissipated into the external environment, preventing the heat dissipation channel from being blocked due to displacement of the electrode assembly. When the distance between the outer surface of the insulating tape and the inner surface of the cover is less than 2mm, the excessively small gap makes it difficult for the heat generated during charging and discharging to dissipate effectively. This localized temperature rise can trigger side reactions such as electrolyte decomposition and separator melting, further leading to an internal short circuit. The short circuit causes a sharp increase in current, generating a large amount of heat, creating a vicious cycle that ultimately leads to battery fire or explosion. Conversely, when the distance between the outer surface of the insulating tape and the inner surface of the cover is greater than 6mm, the excessive gap can result in insufficient fixation between the electrode assembly and the cover when the battery is subjected to external forces such as vibration or impact, making the electrode assembly prone to loosening inside the battery.

[0068] In this invention, a first adhesive tape is provided on the outer surface of the first region, and the first adhesive tape at least completely covers the first region. A second adhesive tape is provided on the outer surface of the second region, and the second adhesive tape at least completely covers the second region. Applying adhesive tape to the first / second region protects the solder joints in the welding area and prevents the tabs from breaking or the solder joints from cracking due to stress concentration caused by battery vibration.

[0069] In this invention, in the width direction, the ratio of the size of the first adhesive tape to the dimension L1 of the positive electrode tab extending beyond the diaphragm is 1-3, for example, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, or 3. In the width direction, the ratio of the size of the second adhesive tape to the dimension L2 of the negative electrode tab extending beyond the diaphragm is 1-3, for example, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, or 3.

[0070] When the ratio of the size of the adhesive tape to the size of the tab exceeding the diaphragm is within a certain range, the adhesive tape can cover the root of the tab and part of the electrode sheet, ensuring the foundation is fixed and sealed, and can also expand the bonding area. The increased coverage area can disperse local stress to a larger area, reduce the risk of breakage of the welding point or tab, and disperse the direct pulling of external forces such as vibration or impact on the root of the tab.

[0071] In this invention, corner adhesive is provided at least at two corners of the electrode assembly away from the cover plate. The thickness of the corner adhesive is 0.03mm-0.06mm, for example, 0.03mm, 0.04mm, 0.05mm, or 0.06mm. Along the width direction, the dimensions of the corner adhesive are 10mm-25mm, for example, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm, 21mm, 22mm, 23mm, 24mm, or 25mm. Along the height direction of the battery, the dimensions of the corner adhesive are 40mm-60mm, for example, 40mm, 45mm, 50mm, 55mm, or 60mm. Applying corner adhesive to the corner area formed by the winding of the electrode assembly can firmly bond the separator and the positive and negative electrode sheets in the corner area together, preventing the structure from loosening or deforming due to external forces during battery assembly, transportation or use, thereby improving the overall structural stability of the battery.

[0072] In one example, the housing comprises a square aluminum shell.

[0073] It should be noted that the numerical designations such as "first" and "second" in this utility model are only used to distinguish different substances or methods of use, and do not represent a difference in order.

[0074] The present invention will be described in detail below through embodiments. The embodiments described herein are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0075] The following examples illustrate the battery of this invention.

[0076] Example 1

[0077] The battery includes an electrode assembly and a casing (square aluminum casing); the electrode assembly includes a positive electrode plate, a negative electrode plate, and a separator; the positive electrode plate includes a positive current collector and a positive electrode tab extending from one side of the positive current collector, the positive electrode tab having the same dimensions as the positive current collector in the height direction of the battery; the negative electrode plate includes a negative current collector and a negative electrode tab extending from one side of the negative current collector, the negative electrode tab having the same dimensions as the negative current collector in the height direction of the battery; the positive electrode tab and the negative electrode tab are located on opposite sides of the battery width direction;

[0078] Where L1 is 10mm, L2 is 10mm, L1-L2=0; L1:L3 is 1:0.8, L2:L4 is 1:0.8;

[0079] The ratio of S1:S3 is 1:1.85, and the ratio of S2:S4 is 1:1.85.

[0080] The tensile strength of the positive electrode tab in the width direction is 275 MPa, and the tensile strength of the negative electrode tab in the width direction is 480 MPa; the thickness of the positive electrode tab is 15 μm, and the thickness of the negative electrode tab is 8 μm.

[0081] The battery is placed vertically along its height, with the electrolyte level not exceeding the lower edge of the first region and not exceeding the lower edge of the second region.

[0082] Along the thickness direction of the battery, the surfaces of the first straight portion welded to the positive electrode tab and the second straight portion welded to the negative electrode tab are staggered.

[0083] In the width direction, the ratio of the size of the first adhesive tape to L1 is 2.3, and the ratio of the size of the second adhesive tape to L2 is 2.3;

[0084] The positive electrode active material is a ternary nickel-cobalt-manganese (NCM111).

[0085] Example 2

[0086] The procedure is the same as in Example 1, except that the specific differences are as follows:

[0087] L1 is 8mm, L2 is 6mm, L1-L2=2; L1:L3 is 1:0.6, L2:L4 is 1:0.5;

[0088] The ratio of S1 to S3 is 1:1.4, and the ratio of S2 to S4 is 1:1.4.

[0089] The tensile strength of the positive electrode tab in the width direction is 230 MPa, and the tensile strength of the negative electrode tab in the width direction is 410 MPa; the thickness of the positive electrode tab is 12 μm, and the thickness of the negative electrode tab is 6 μm.

[0090] In the width direction, the ratio of the size of the first adhesive tape to L1 is 1.2, and the ratio of the size of the second adhesive tape to L2 is 1.2.

[0091] Example 3

[0092] The procedure is the same as in Example 1, except that the specific differences are as follows:

[0093] L1 is 15mm, L2 is 13mm, L1-L2=2; L1:L3 is 1:0.98, L2:L4 is 1:0.86;

[0094] S1:S3 is 1:3, S2:S4 is 1:3;

[0095] The tensile strength of the positive electrode tab in the width direction is 320 MPa, and the tensile strength of the negative electrode tab in the width direction is 550 MPa; the thickness of the positive electrode tab is 18 μm, and the thickness of the negative electrode tab is 10 μm.

[0096] In the width direction, the ratio of the size of the first adhesive tape to L1 is 2.9, and the ratio of the size of the second adhesive tape to L2 is 2.9.

[0097] Example 4 group

[0098] This set of examples is used to verify the impact of changes to "L1:L3 and L2:L4".

[0099] This set of embodiments is based on Embodiment 1, except that L1:L3 and L2:L4 are changed, as follows:

[0100] Example 4a, L1:L3 is 1:0.4, L2:L4 is 1:0.4;

[0101] In Example 4b, L1:L3 is 1:1.5 and L2:L4 is 1:1.5.

[0102] Example 5

[0103] Used to verify the impact of changes to "L1-L2".

[0104] The same procedure was performed as in Example 1, except that L1-L2 were changed. Specifically, L1 was 15mm, L2 was 9mm, and L1-L2 was 6mm.

[0105] All of the above embodiments satisfy the following:

[0106] In the thickness direction, the distance between the surface where the first straight portion is welded to the positive electrode tab and the surface where the second straight portion is welded to the negative electrode tab is 0.05mm-0.4mm;

[0107] Corner adhesive is provided at the two corners of the electrode assembly away from the cover plate; the thickness of the corner adhesive is 0.03mm-0.06mm; the size of the corner adhesive is 10mm-25mm along the width direction; and the size of the corner adhesive is 40mm-60mm along the height direction of the battery.

[0108] Along the height direction of the battery, the distance from the center line of the first region to the upper edge of the first straight part is less than the distance from the center line of the first region to the lower edge of the first straight part, and the distance from the center line of the second region to the upper edge of the second straight part is less than the distance from the center line of the second region to the lower edge of the second straight part.

[0109] The battery is placed vertically along the height direction, and the dimension between the horizontal line where the center of the electrode assembly is located and the horizontal line where the center of gravity of the electrode assembly is located is less than or equal to 1 / 6 of the height of the electrode assembly.

[0110] The electrode assembly includes an arc region and a straight region connected to the arc region. An insulating adhesive paper is provided on the outer surface of the arc region at the first end of the electrode assembly, and the distance from the outer surface of the insulating adhesive paper to the inner surface of the cover plate in the height direction of the battery is 2mm-6mm.

[0111] A first adhesive tape is provided on the outer surface of the first region, and the first adhesive tape at least completely covers the first region; a second adhesive tape is provided on the outer surface of the second region, and the second adhesive tape at least completely covers the second region.

[0112] Comparative Example 1

[0113] The procedure is the same as in Example 1, except that L1:L3 and L2:L4 are different, as follows:

[0114] In Comparative Example 1a, the ratio of L1:L3 is 1:0.3, and the ratio of L2:L4 is 1:0.3;

[0115] Comparative Example 1b, L1:L3 is 1:2, and L2:L4 is 1:2.

[0116] Comparative Example 2

[0117] The procedure is the same as in Example 1, except that S1:S3 and S2:S4 are as follows:

[0118] In Comparative Example 2a, the ratio of S1 to S3 is 1:1.2, and the ratio of S2 to S4 is 1:1.2.

[0119] Comparative Example 2b, S1:S3 is 1:3.5, and S2:S4 is 1:3.5.

[0120] Test case

[0121] (1) Internal resistance test

[0122] The batteries prepared in the examples and comparative examples were subjected to internal resistance testing. The specific testing methods are as follows:

[0123] Connect the positive and negative terminals of the battery to the corresponding terminals of the cell internal resistance tester. Turn on the tester, select the ACR test mode, set the test frequency to 1kHz, and set the test current to 100mA. Start the tester and begin the test. The tester will automatically apply AC current and measure the battery's internal resistance, recording the initial internal resistance.

[0124] Then the battery is vibrated according to the specifications in GB 38031-2025;

[0125] Test the internal resistance of the vibrated battery using the method described above, and record the internal resistance after vibration.

[0126] The differences between the initial internal resistance and the internal resistance after vibration and the initial internal resistance are recorded in Table 1.

[0127] (2) K-value test

[0128] The batteries prepared in the examples and comparative examples were subjected to K-value testing. The specific testing methods are as follows:

[0129] At 25℃, the battery was discharged at a standard 1C constant current to the lower limit voltage and left to stand for 10 minutes; then charged at a standard 1C constant current and constant voltage to the upper limit voltage, with a cutoff current of 0.05C, and left to stand for 10 minutes; the battery was discharged at a standard 1C constant current to the lower limit voltage to obtain the actual battery capacity C0; left to stand for 10 minutes; charged with 1C0 for 30 minutes, which is 50% SOC, and left to stand for another 10 minutes; the battery was placed at 45℃ and left to stand for 2 days; then at 25℃, after leaving to stand for 2 days, the battery voltage was tested and recorded as OCV1; then at 25℃, after leaving to stand for another 5 days, the battery voltage was tested and recorded as OCV2. K value = (OCV1 - OCV2) / 5 days, in mV / h. The results are recorded in Table 1. The upper and lower voltage limits are determined by the cathode system. For example, the upper and lower voltage limits of lithium iron phosphate batteries are 3.65V and 2.2V, respectively; the upper and lower voltage limits of lithium cobalt oxide batteries are 4.5V and 3V, respectively; and the upper and lower voltage limits of ternary nickel-cobalt-manganese batteries are 4.3V and 2.8V, respectively.

[0130] Table 1

[0131] K value (mV / h) Initial internal resistance (mΩ) Internal resistance difference (mΩ) Example 1 0.021 0.93 0.06 Example 2 0.025 0.95 0.08 Example 3 0.024 0.91 0.06 Example 4a 0.021 0.94 0.1 Example 4b 0.046 0.93 0.05 Example 5 0.025 0.95 0.12 Comparative Example 1a 0.026 0.94 0.18 Comparative Example 1b 0.097 0.94 0.05 Comparative Example 2a 0.027 0.99 0.07 Comparative Example 2b 0.03 0.92 0.29

[0132] As can be seen from Table 1, compared with the comparative example, the battery of this invention can significantly improve the problem of increased internal resistance after battery vibration, and has a lower K value.

[0133] The preferred embodiments of this utility model have been described in detail above; however, this utility model is not limited thereto. Within the scope of the technical concept of this utility model, various simple modifications can be made to the technical solution of this utility model, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed by this utility model and are all within the protection scope of this utility model.

Claims

1. A battery, characterized in that, Includes electrode assembly and housing; The electrode assembly includes a positive electrode plate, a negative electrode plate, and a separator; the positive electrode plate includes a positive current collector and a positive tab extending from one side of the positive current collector, and the size of the positive tab is the same as the size of the positive current collector in the height direction of the battery; the negative electrode plate includes a negative current collector and a negative tab extending from one side of the negative current collector, and the size of the negative tab is the same as the size of the negative current collector in the height direction of the battery; the positive tab and the negative tab are respectively located on both sides of the width direction of the battery; The outer casing includes a cover plate and a bottom shell, the bottom shell and the cover plate forming a receiving cavity for accommodating the electrode assembly, the cover plate including a positive electrode post and a negative electrode post; In the width direction, the positive electrode tab extends beyond the diaphragm by a dimension L1 of 6mm-15mm, and the negative electrode tab extends beyond the diaphragm by a dimension L2 of 6mm-15mm; The battery further includes a positive electrode adapter and a negative electrode adapter; the positive electrode adapter includes a first straight portion and a first connecting portion, the negative electrode adapter includes a second straight portion and a second connecting portion, the first straight portion is welded to the positive electrode tab, the first connecting portion is connected to the positive electrode post, the second straight portion is welded to the negative electrode tab, and the second connecting portion is connected to the negative electrode post; The first straight portion has a dimension of L3 in the width direction, and the second straight portion has a dimension of L4 in the width direction. The ratio of L1 to L3 is 1:(0.4-1.5), and the ratio of L2 to L4 is 1:(0.4-1.5). The welding area between the first straight portion and the positive electrode tab is the first region, and the area of ​​the first region is S1; the welding area between the second straight portion and the negative electrode tab is the second region, and the area of ​​the second region is S2; the area of ​​the first straight portion is S3, and the area of ​​the second straight portion is S4; S1:S3 is 1:(1.35-3), and S2:S4 is 1:(1.35-3).

2. The battery according to claim 1, characterized in that, L1:L3 is 1:(0.5-0.98); And / or, L2:L4 is 1:(0.5-0.98); And / or, the tensile strength of the positive electrode tab in the width direction is 150MPa-400MPa; And / or, the tensile strength of the negative electrode tab in the width direction is 300MPa-650MPa; And / or, the thickness of the positive electrode tab is 8μm-25μm; And / or, the thickness of the negative electrode tab is 3μm-15μm.

3. The battery according to claim 1 or 2, characterized in that, The battery also includes an electrolyte located within the casing; The battery is placed vertically along the height direction, and the electrolyte level does not exceed the lower edge of the first region and the lower edge of the second region; wherein, the lower edge of the first region refers to the edge of the first region away from the cover plate, and the lower edge of the second region refers to the edge of the second region away from the cover plate.

4. The battery according to claim 1 or 2, characterized in that, Along the thickness direction of the battery, the surfaces of the first straight portion welded to the positive electrode tab and the surfaces of the second straight portion welded to the negative electrode tab are staggered.

5. The battery according to claim 4, characterized in that, In the thickness direction, the distance between the surface of the first straight portion welded to the positive electrode tab and the surface of the second straight portion welded to the negative electrode tab is 0.05mm-0.4mm.

6. The battery according to claim 1 or 2, characterized in that, L1-L2≤5mm; And / or, at least two corners of the electrode assembly away from the cover plate are provided with corner adhesive; the thickness of the corner adhesive is 0.03mm-0.06mm; the size of the corner adhesive is 10mm-25mm along the width direction; and the size of the corner adhesive is 40mm-60mm along the height direction of the battery.

7. The battery according to claim 1 or 2, characterized in that, Along the height direction of the battery, the distance from the center line of the first region to the upper edge of the first straight portion is less than the distance from the center line of the first region to the lower edge of the first straight portion; wherein, the upper edge of the first straight portion refers to the edge of the first straight portion close to the cover plate, and the lower edge of the first straight portion refers to the edge of the first straight portion away from the cover plate. And / or, along the height direction of the battery, the distance from the center line of the second region to the upper edge of the second straight portion is less than the distance from the center line of the second region to the lower edge of the second straight portion; wherein, the upper edge of the second straight portion refers to the edge of the second straight portion close to the cover plate, and the lower edge of the second straight portion refers to the edge of the second straight portion away from the cover plate; And / or, the battery is placed vertically along the height direction, and the dimension between the horizontal line where the center of the electrode assembly is located and the horizontal line where the center of gravity of the electrode assembly is located is less than or equal to 1 / 6 of the height of the electrode assembly.

8. The battery according to claim 1 or 2, characterized in that, The electrode assembly includes an arc-shaped region and a straight region connected to the arc-shaped region; an insulating adhesive paper is provided on the outer surface of the arc-shaped region located at the first end of the electrode assembly; wherein, the first end of the electrode assembly refers to the end of the electrode assembly close to the cover plate; In the height direction of the battery, the distance from the outer surface of the insulating tape to the inner surface of the cover plate is 2mm-6mm.

9. The battery according to claim 1 or 2, characterized in that, A first adhesive tape is provided on the outer surface of the first area, and the first adhesive tape at least completely covers the first area; And / or, a second adhesive tape is provided on the outer surface of the second region, the second adhesive tape at least completely covering the second region.

10. The battery according to claim 9, characterized in that, In the width direction, the ratio of the size of the first adhesive tape to the dimension L1 of the positive electrode tab extending beyond the diaphragm is 1-3; And / or, in the width direction, the ratio of the size of the second adhesive tape to the size L2 of the negative electrode tab extending beyond the diaphragm is 1-3.

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