A battery

Abstract

The application provides a battery, comprising a battery cell, a shell, a positive pole post assembly and a negative pole post assembly, the battery cell comprises a battery cell body, a positive tab and a negative tab, the positive tab and the negative tab are led out from two ends of the battery cell body in the length direction of the battery, the positive tab and the negative tab are welded with the positive pole post assembly and the negative pole post assembly respectively, the thickness of the positive tab is greater than the thickness of the negative tab, the width W1 of the negative tab in the width direction of the battery is greater than the width W2 of the positive tab in the width direction of the battery, the width of the welding area of the negative tab and the negative pole post assembly and the welding area of the positive tab and the positive pole post assembly in the width direction of the battery is W3 and W4 respectively, and 0.1<= (W1-W3) / (W2-W4) <=20. The battery has high energy density, high reliability, good overall overcurrent capacity, and the connection strength of the positive and negative tab pole post assemblies is sufficient and balanced.

Description

[0001] This application is a divisional application based on the original invention patent application number 2024114283194, filed on October 14, 2024, entitled "A Battery". Technical Field

[0002] This application relates to the field of battery technology, and in particular to a battery. Background Technology

[0003] A battery consists of a positive electrode tab, a negative electrode tab, a positive terminal assembly, and a negative terminal assembly. The positive and negative tabs are welded to the positive and negative terminal assemblies, respectively, forming a charging and discharging circuit. If the connection between the positive and negative tabs and the positive and negative terminal assemblies breaks, it will cause electrical connection failure in the battery, which is detrimental to reliable battery operation. An imbalance in the overcurrent capacity of the positive and negative electrodes will result in poor overall overcurrent capacity of the battery. Summary of the Invention

[0004] The purpose of this application is to provide a battery with high energy density and high reliability.

[0005] The battery provided in this application includes a cell, a casing, a positive electrode assembly, and a negative electrode assembly. The cell is located inside the casing, and the positive electrode assembly and the negative electrode assembly are disposed in the casing. The cell includes a cell body, a positive electrode tab, and a negative electrode tab. In the length direction of the battery, the positive electrode tab and the negative electrode tab are respectively led out from both ends of the cell body. The positive electrode tab and the negative electrode tab are respectively welded to the positive electrode assembly and the negative electrode assembly. The length of the battery is L, where L≥400mm. The thickness of the positive electrode tab is greater than the thickness of the negative electrode tab. The width of the negative electrode tab in the width direction of the battery is W1, and the width of the positive electrode tab in the width direction of the battery is W2, where W1>W2.

[0006] The width of the welding area between the negative electrode tab and the negative electrode post assembly in the width direction of the battery is W3, and the width of the welding area between the positive electrode tab and the positive electrode post assembly in the width direction of the battery is W4, 0.1≤(W1-W3) / (W2-W4)≤20.

[0007] Because the battery's length is greater than or equal to 400mm, the cell itself is also relatively long. A longer cell increases the battery's energy density. Furthermore, because the negative electrode tab is relatively thin (the thickness of the negative electrode tab is less than that of the positive electrode tab), each negative electrode tab (multiple negative electrode tabs stacked together form a negative electrode tab) is also relatively thin (the thickness of a single negative electrode tab is less than that of a single positive electrode tab). Therefore, the current collector of the negative electrode (drawn from the current collector of the negative electrode tab) within the cell is also relatively thin. With a fixed negative electrode thickness, a thinner current collector results in a thicker active material layer coated on both sides of the current collector. A thicker active material layer further enhances the battery's energy density, thus resulting in a higher energy density for this battery.

[0008] Because the negative electrode tab is relatively thin (its thickness is less than that of the positive electrode tab), the connection between the negative electrode tab and the negative electrode terminal assembly is prone to breakage, resulting in poor battery reliability. In addition, the battery is relatively long, and the longer the battery is, the greater the stress on the connection between the negative electrode tab and the negative electrode terminal assembly at one end of the battery's length, further exacerbating the risk of breakage at the connection. This application improves the strength of the connection between the negative electrode tab and the negative electrode terminal assembly by making the width of the negative electrode tab greater than that of the positive electrode tab, thereby reducing the risk of breakage at the connection and thus making the battery more reliable.

[0009] If (W1-W3) / (W2-W4) is too large, it means that W1-W3 is too large and / or W2-W4 is too small. An excessively large W1-W3 will result in insufficient connection strength between the negative electrode tab 23 and the negative electrode post assembly 32. If (W1-W3) / (W2-W4) is too small, it means that W2-W4 is too large and / or W1-W3 is too small. An excessively large W2-W4 will result in insufficient connection strength between the positive electrode tab 22 and the positive electrode post assembly 31. A value of 0.1 ≤ (W1-W3) / (W2-W4) ≤ 20 ensures that the connection strength between the negative electrode tab 23 and the negative electrode post assembly 32, as well as the connection strength between the positive electrode tab 22 and the positive electrode post assembly 31, is sufficient and relatively balanced. Attached Figure Description

[0010] Figure 1 An exploded view of one embodiment of the battery provided in this application;

[0011] Figure 2 for Figure 1 Another perspective view of the assembled state;

[0012] Figure 3 for Figure 1 A plan view of the battery cell and cover plate;

[0013] Figure 4 for Figure 1 An enlarged view of the location of the negative electrode tab behind the hidden negative electrode insulating protective cover;

[0014] Figure 5 for Figure 1 Enlarged view of the insulating protective cover for the positive electrode;

[0015] Figure 6 A simplified diagram illustrating the cell structure of one embodiment of the battery provided in this application;

[0016] Figure 7 This is a simplified diagram of the casing structure of one embodiment of the battery provided in this application.

[0017] The annotations in the attached figures are explained as follows:

[0018] 1. Shell, 11. Shell body, 11a. Protrusion, 11b. Recess, 12. Cover plate, C. Injection hole;

[0019] 2 battery cells, 21 battery cell body, 22 positive electrode tab, 23 negative electrode tab;

[0020] 31 Positive terminal assembly, 32 Negative terminal assembly;

[0021] 4. Adapters;

[0022] 51 Positive electrode insulating protective cover, 52 Negative electrode insulating protective cover, 5a First support part, A First side wall, 5b Second support part, B Second side wall, 5c Electrode ear receiving part. Detailed Implementation

[0023] This application provides a battery. To enable those skilled in the art to better understand the technical solution of this application, the following detailed description is provided in conjunction with the accompanying drawings and specific embodiments.

[0024] like Figures 1-4 As shown, the battery includes a casing 1, a cell 2, and an electrode assembly. The casing 1 has a liquid filling port C (see [reference]). Figure 2 Electrolyte is injected into the housing 1 through the injection hole C. The battery cell 2 is located inside the housing 1. The terminal assembly is disposed within the housing 1. The terminal assembly includes a positive terminal assembly 31 and a negative terminal assembly 32. The positive terminal assembly 31 includes at least a positive terminal and may optionally include an adapter 4. The negative terminal assembly 32 includes at least a negative terminal and may optionally include an adapter 4.

[0025] The battery cell 2 includes a cell body 21 and electrode tabs. The electrode tabs include a positive electrode tab 22 and a negative electrode tab 23. Along the length of the battery, the positive electrode tab 22 and the negative electrode tab 23 extend from both ends of the cell body 21. The battery is generally rectangular, comprising two large, oppositely arranged surfaces and four smaller surfaces located between them. The longer side of each large surface is the length of the battery, the shorter side is the width, and the direction perpendicular to the large surface is the thickness. The length, width, and thickness directions of the battery are mutually perpendicular.

[0026] The positive electrode tab 22 is welded to the positive electrode post assembly 31, and the negative electrode tab 23 is welded to the negative electrode post assembly 32. If the positive electrode post assembly 31 does not have an adapter 4, then the positive electrode tab 22 is welded to the positive electrode post. If the positive electrode post assembly 31 has an adapter 4, then the positive electrode tab 22 is welded to one side of the adapter 4, and the positive electrode post is welded to the other side of the adapter 4. If the negative electrode post assembly 32 does not have an adapter 4, then the negative electrode tab 23 is welded to the negative electrode post. If the negative electrode post assembly 32 has an adapter 4, then the negative electrode tab 23 is welded to one side of the adapter 4, and the negative electrode post is welded to the other side of the adapter 4.

[0027] The cell body 21 includes a positive electrode and a negative electrode, which are arranged alternately, with a separator between adjacent positive and negative electrode sheets. In some embodiments, the positive and negative electrode sheets are arranged alternately along the thickness direction of the battery, making the cell body 21 a stacked structure. In some embodiments, the positive and negative electrode sheets are wound together, and are arranged alternately along a direction perpendicular to the winding center line, making the cell body 21 a wound structure.

[0028] The positive and negative electrode sheets have similar structures, both including a current collector and active material layers coated on both sides of the current collector. The active material layer of the positive electrode sheet includes positive active material, conductive agent, binder, etc., and the positive active material includes nickel-cobalt-manganese ternary materials, lithium iron phosphate materials, lithium manganese iron phosphate materials, lithium nickel manganese oxide materials, etc. The active material layer of the negative electrode sheet includes negative active material, conductive agent, binder, etc. The negative active material includes artificial graphite, natural graphite, silicon-based materials, etc. This application does not limit the material of the current collector, as long as it is conductive and will not cause adverse chemical changes in the battery. For example, stainless steel, aluminum, nickel, titanium, sintered carbon, or aluminum or stainless steel with a surface treatment of carbon, nickel, titanium, silver, etc., can be used.

[0029] In the positive electrode sheet, the uncoated portion of the current collector protrudes beyond the coated portion, forming a single positive electrode tab. Multiple positive electrode tabs are stacked to form a positive electrode tab 22. In the negative electrode sheet, the uncoated portion of the current collector protrudes beyond the coated portion, forming a single negative electrode tab. Multiple negative electrode tabs are stacked to form a single negative electrode tab 23.

[0030] The battery length is L, where L ≥ 400mm. For example, L can be equal to 500mm, 600mm, or 700mm. The longer the battery length, the longer the cell body 21, which is more conducive to improving the battery energy density.

[0031] The thickness of the positive electrode tab 22 is greater than the thickness of the negative electrode tab 23. The thickness of a single positive electrode tab is greater than the thickness of a single negative electrode tab. The thickness of the positive electrode tab 22 is equal to the number of single positive electrode tabs multiplied by its thickness. Similarly, the thickness of the negative electrode tab 23 is equal to the number of single negative electrode tabs multiplied by its thickness. Since the single negative electrode tab is drawn from the current collector of the negative electrode sheet, the thinner the single negative electrode tab, the thinner the current collector. For a given negative electrode sheet thickness, a thinner current collector results in a thicker active material layer, which is more conducive to increasing battery energy density.

[0032] The width of the negative electrode tab 23 in the width direction of the battery is W1, and the width of the positive electrode tab 22 in the width direction of the battery is W2, where W1 > W2.

[0033] Because the negative electrode tab 23 is relatively thin (the thickness of the negative electrode tab 23 is less than the thickness of the positive electrode tab 22), the connection between the negative electrode tab 23 and the negative electrode post assembly 32 is prone to breakage, resulting in poor battery reliability. In addition, the battery is relatively long (greater than or equal to 400mm). The longer the battery is, the greater the stress on the connection between the negative electrode tab 23 and the negative electrode post assembly 32 at one end of the battery length, which further exacerbates the risk of breakage at the connection between the negative electrode tab 23 and the negative electrode post assembly 32. This application improves the strength of the connection between the negative electrode tab 23 and the negative electrode post assembly 32 by making the width of the negative electrode tab 23 greater than the width of the positive electrode tab 22, thereby reducing the risk of breakage at the connection between the negative electrode tab 23 and the negative electrode post assembly 32, and thus making the battery more reliable.

[0034] Furthermore, because the negative electrode tab 23 is thinner (the thickness of the negative electrode tab 23 is less than that of the positive electrode tab 22), the negative electrode current carrying capacity is less than that of the positive electrode, resulting in poor overall battery current carrying capacity. In addition, the battery is relatively long (greater than or equal to 400mm). The longer the battery is, the greater the impedance, which further exacerbates the difference between the negative and positive electrode current carrying capacity. This application improves the negative electrode current carrying capacity by making the width of the negative electrode tab 23 greater than that of the positive electrode tab 22. This allows the width of the welding area between the negative electrode tab 23 and the negative electrode terminal assembly 32 to be designed to be greater than the width of the welding area between the positive electrode tab 22 and the positive electrode terminal assembly 31. This improves the negative electrode current carrying capacity and makes the positive and negative electrode current carrying capacity more balanced, thereby improving the overall battery current carrying capacity.

[0035] By comprehensively controlling the relationship between the battery length L and W1-W2, the consistency of the connection strength between the positive electrode tab 22 and the positive electrode post assembly 31 and the negative electrode tab 23 and the negative electrode post assembly 32 can be improved, avoiding connection failure of the thinner negative electrode tab 23 and the negative electrode post assembly 32. Specifically, the range of L / (W1-W2) is controlled as follows: 9≤L / (W1-W2)≤600. For example, L / (W1-W2) can be equal to 9, 10, 30, 60, 100, or 200. If the ratio is too large, it means that L is too large and / or W1-W2 is too small. If W1-W2 is too small, it means that W2 is too large or W1 is too small. If W1 is too small, the connection strength between the negative electrode tab 23 and the negative electrode post assembly 32 will be insufficient and it will be easy to break, resulting in low battery reliability. If W2 is too large, the positive electrode tab 22 will excessively hinder the flow of electrolyte from the end of the positive electrode tab 22 to the cell body 21, which is not conducive to the rapid and uniform wetting of the cell body 21 by the electrolyte. If this ratio is too small, it means L is too small and / or W1-W2 is too large. A large W1-W2 means W2 is too small or W1 is too large. An excessively large W1 will cause the negative electrode tab 23 to excessively obstruct the flow of electrolyte from the end of the negative electrode tab 23 to the cell body 21, hindering the rapid and uniform wetting of the cell body 21 by the electrolyte. An excessively small W2 will result in insufficient connection strength between the positive electrode tab 22 and the positive electrode post assembly 31, making it prone to breakage and leading to low battery reliability. A ratio of 9 ≤ L / (W1-W2) ≤ 600 ensures rapid and uniform wetting of the cell body 21 by the electrolyte and also guarantees high battery reliability. Furthermore, this range ensures that, given a fixed width W2 for the positive electrode tab 22, the battery length L is positively correlated with the width W1 for the negative electrode tab 23; that is, the larger L is, the larger W1 is, and the smaller L is, the smaller W1 is. The larger L is, the greater the force at the connection point between the negative electrode tab 23 and the negative electrode post assembly 32, and the greater the risk of breakage at the connection point. Therefore, it is necessary to make the width W1 of the negative electrode tab 23 larger to increase the strength of the connection point between the negative electrode tab 23 and the negative electrode post assembly 32 to a greater extent.

[0036] In some embodiments, 0.05 ≤ (W-W1) / (W-W2) ≤ 0.98. For example, (W-W1) / (W-W2) can be equal to 0.1, 0.4, 0.6, 0.8, or 0.9. Here, W is the width of the cell body along the length of the battery. If this ratio is too large, it means W-W1 is too large and / or W-W2 is too small, resulting in an imbalance in the connection strength between the positive and negative tabs and the positive and negative terminal components. If this ratio is too small, it means W-W1 is too small and / or W-W2 is too large, which also results in an imbalance in the connection strength between the positive and negative tabs and the positive and negative terminal components.

[0037] In some embodiments, 10mm ≤ W-W1 ≤ 100mm. For example, W-W1 can be equal to 10mm, 15mm, 20mm, 50mm, 70mm, 90mm, or 100mm. If the difference is too large, it means that W1 is too small, resulting in a poor connection strength between the negative electrode tab 23 and the negative electrode post assembly 32. This leads to an imbalance in the connection strength between the positive and negative electrode tabs and the positive and negative electrode post assemblies, and it cannot effectively improve the negative electrode current carrying capacity. Consequently, it cannot compensate for the insufficient negative electrode current carrying capacity caused by the thickness of the negative electrode tab 23 being less than that of the positive electrode tab 22. If the difference is too small, it means that W1 is too large, causing the negative electrode tab 23 to excessively hinder the electrolyte in the housing 1 from the end where the negative electrode tab 23 is led out to the cell body 21. This is not conducive to the rapid and uniform wetting of the cell body 21 by the electrolyte. Specifically, the width W1 of the negative electrode tab 23 in the width direction of the battery can be in the range of 15mm≤W1≤80mm, for example, W1 can be equal to 15mm, 30mm, 50mm, 60mm, or 80mm.

[0038] In some embodiments, 12mm ≤ W-W2 ≤ 100mm. For example, W-W2 can be equal to 13mm, 20mm, 50mm, 70mm, or 90mm. If this difference is too large, it means W2 is too small, resulting in poor connection strength between the positive electrode tab 22 and the positive electrode post assembly 31, causing an imbalance in the connection strength between the positive and negative electrode tabs and the positive and negative electrode post assemblies. If this difference is too small, it means W2 is too large, causing the positive electrode tab 22 to excessively hinder the electrolyte in the casing 1 from the end leading out of the positive electrode tab 22 to wet the cell body 21, which is not conducive to the rapid and uniform wettation of the cell body 21 by the electrolyte. Specifically, the width W2 of the positive electrode tab 22 in the battery width direction can be in the range of 13mm ≤ W2 ≤ 60mm, for example, W2 can be equal to 20mm, 40mm, or 50mm.

[0039] In some embodiments, 1.1 ≤ W3 / W4 ≤ 8, for example, W3 / W4 can be equal to 1.1, 2, 3, 5, 6, 6.5, or 8. Here, W3 is the width of the welding area between the negative electrode tab 23 and the negative electrode post assembly 32 in the battery width direction, and W4 is the width of the welding area between the positive electrode tab 22 and the positive electrode post assembly 31 in the battery width direction. Since the lower limit of this ratio is greater than 1, W3 is greater than W4. W3 being greater than W4 can compensate for the insufficient negative electrode current carrying capacity caused by the thickness of the negative electrode tab 23 being less than the thickness of the positive electrode tab 22. If this ratio is too large, it means W3 is too large, which will cause the positive electrode current carrying capacity to be less than the negative electrode current carrying capacity, resulting in poor overall battery current carrying capacity. If this ratio is too small, it means W3 is too small, which cannot compensate for the insufficient negative electrode current carrying capacity caused by the thickness of the negative electrode tab 23 being less than the thickness of the positive electrode tab 22.

[0040] In some embodiments, 0.1 ≤ (W1-W3) / (W2-W4) ≤ 20. For example, (W1-W3) / (W2-W4) can be equal to 0.1, 1, 5, 10, or 15. If this ratio is too large, it means that W1-W3 is too large and / or W2-W4 is too small. If W1-W3 is too large, the connection strength between the negative electrode tab 23 and the negative electrode post assembly 32 will be insufficient. If this ratio is too small, it means that W2-W4 is too large and / or W1-W3 is too small. If W2-W4 is too large, the connection strength between the positive electrode tab 22 and the positive electrode post assembly 31 will be insufficient. 0.1 ≤ (W1-W3) / (W2-W4) ≤ 20 ensures that the connection strength between the negative electrode tab 23 and the negative electrode post assembly 32, as well as the connection strength between the positive electrode tab 22 and the positive electrode post assembly 31, is sufficient and relatively balanced.

[0041] In some embodiments, 5mm ≤ W1-W3 ≤ 70mm, where W1-W3 is the width of the portion of the negative electrode tab 23 not welded to the negative electrode terminal assembly 32. A larger W1-W3 indicates a higher connection strength between the negative electrode tab 23 and the negative electrode sheet, but a smaller W3 indicates a lower connection strength between the negative electrode tab 23 and the negative electrode terminal assembly 32. The range of 5mm ≤ W1-W3 ≤ 70mm ensures a relatively high and balanced connection strength between the negative electrode tab 23 and the negative electrode terminal assembly 32, as well as the negative electrode sheet. Specifically, the width W3 of the welding area between the negative electrode tab 23 and the negative electrode terminal assembly 32 in the battery width direction can be in the range of 10mm ≤ W3 ≤ 55mm, for example, W3 can be equal to 20mm, 40mm, or 50mm.

[0042] In some embodiments, 8mm ≤ W2-W4 ≤ 75mm, where W2-W4 is the width of the portion of the positive electrode tab 22 not welded to the positive electrode post assembly 31. A larger W2-W4 indicates a higher connection strength between the positive electrode tab 22 and the positive electrode plate, but a smaller W4 indicates a lower connection strength between the positive electrode tab 22 and the positive electrode post assembly 31. The range of 8mm ≤ W2-W4 ≤ 75mm ensures a relatively high and balanced connection strength between the positive electrode tab 22 and the positive electrode post assembly 31, as well as the positive electrode plate. Specifically, the width W4 of the welding area between the positive electrode tab 22 and the positive electrode post assembly 31 in the battery width direction can be in the range of 5mm ≤ W4 ≤ 50mm, for example, W4 can be equal to 5mm, 10mm, 30mm, 40mm, or 50mm.

[0043] In some embodiments, the orthographic projection of the negative electrode tab 23 onto the plane containing the electrolyte injection hole at least partially overlaps with the electrolyte injection hole. With this design, given a fixed battery width, the width W1 of the negative electrode tab 23 can be set wider. Correspondingly, the width W3 of the welding area between the negative electrode tab 23 and the negative electrode post assembly 32 can also be set wider, thus compensating for the insufficient negative electrode current carrying capacity caused by the thickness of the negative electrode tab 23 being less than that of the positive electrode tab 22, and ensuring sufficient connection strength between the negative electrode tab 23 and the negative electrode post assembly 32. Furthermore, when overlapped, the negative electrode tab 23 can prevent electrolyte entering from the electrolyte injection hole from directly impacting the cell body, thus protecting the cell body. In this case, the range of W-W1 can be further reduced to: 10mm ≤ W-W1 ≤ 85mm.

[0044] In some embodiments, the orthographic projection of the positive electrode tab 22 onto the plane of the injection hole at least partially overlaps with the injection hole. This design allows for a wider positive electrode tab 22 (W2) with a fixed battery width, ensuring sufficient connection strength between the positive electrode tab 22 and the positive electrode post assembly 31. Furthermore, the overlapping arrangement prevents electrolyte entering through the injection hole from directly impacting the battery cell, thus protecting the battery cell. In this case, the range of W-W2 can be further reduced to: 15mm ≤ W-W2 ≤ 100mm.

[0045] In some embodiments, the orthogonal projection of the negative electrode tab 23 onto the plane containing the electrolyte injection hole does not overlap with the electrolyte injection hole. This design ensures that, with a fixed battery width, the width W1 of the negative electrode tab 23 is narrower, preventing uneven electrolyte wetting caused by an excessively wide negative electrode tab 23.

[0046] In some embodiments, the orthographic projection of the positive electrode tab 22 onto the plane containing the electrolyte injection hole does not overlap with the electrolyte injection hole. This design ensures that, with a fixed battery width, the width W2 of the positive electrode tab 22 is narrower, preventing uneven electrolyte wetting caused by an excessively wide positive electrode tab 22.

[0047] In some embodiments, the electrolyte injection hole is located at one end of the positive electrode tab 22. The orthographic projection of the positive electrode tab 22 on the plane of the injection hole does not overlap with the injection hole. Since the positive electrode tab 22 is relatively thick, it obstructs the electrolyte more severely. Therefore, making the positive electrode tab 22 not overlap with the injection hole can reduce the obstruction of the electrolyte by the positive electrode tab 22, thereby compensating for the uneven electrolyte wetting caused by the thickness of the positive electrode tab 22. In this case, the distance between the injection hole and the cell body in the length direction of the battery is L1, where 2mm≤L1≤10mm. Since the positive electrode tab 22 and the injection hole do not overlap, the electrolyte will directly impact the cell body during injection. 2mm≤L1 ensures that the impact force of the electrolyte on the electrode is not too large. L1 cannot be too large either, as a large L1 will cause excessive flow resistance during the process of electrolyte flowing to the cell body, which is not conducive to the uniform wetting of the cell body by the electrolyte.

[0048] In some embodiments, such as Figure 6 As shown, a transition section is provided between the negative electrode tab 23 and the cell body 21. This transition section acts as a buffer, reducing the possibility of breakage between the negative electrode tab 23 and the cell body 21. Therefore, the width W3 of the welding area of ​​the negative electrode tab 23 can be set larger to increase the connection strength between the negative electrode tab 23 and the negative electrode post assembly 32. The radius of the transition section between the negative electrode tab 23 and the cell body is R1. The larger R1 is, the more beneficial it is to reducing the possibility of breakage between the negative electrode tab 23 and the cell body. Therefore, the larger R1 is, the larger W3 can be set, and the smaller W1-W3 is. Therefore, R1*(W1-W3) should be within a certain range, specifically, the range could be 6mm. 2 ≤R1*(W1-W3)≤350 mm 2 For example, R1*(W1-W3) can be equal to 10 mm. 2 50 mm 2 100 mm 2 200 mm 2 300 mm 2 .

[0049] In some embodiments, such as Figure 6As shown, a transition section is provided between the positive electrode tab 22 and the cell body 21. This transition section acts as a buffer, reducing the possibility of breakage between the positive electrode tab 22 and the cell body 21. Therefore, the width W4 of the welding area of ​​the positive electrode tab 22 can be set larger to increase the connection strength between the positive electrode tab 22 and the positive electrode post assembly 31. The radius of the transition section between the positive electrode tab 22 and the cell body 21 is R2. The larger R2 is, the more beneficial it is to reducing the possibility of breakage between the positive electrode tab 22 and the cell body. Therefore, the larger R2 is, the larger W4 can be set, and the smaller W2 - W4 is. Therefore, R2 * (W2 - W4) should be within a certain range, specifically, the range can be 10 mm. 2 ≤R2*(W2-W4)≤360 mm 2 For example, R2*(W2-W4) can be equal to 10 mm. 2 50 mm 2 100 mm 2 200 mm 2 300 mm 2 350 mm 2 360 mm 2 .

[0050] In some embodiments, such as Figure 7 As shown, the casing 1 includes a casing body 11 and two cover plates 12. Along the length of the battery, the casing body 11 has openings at both ends, and the two cover plates 12 respectively close these openings. The positive electrode post assembly 31 is disposed on one cover plate 12, and the negative electrode post assembly 32 is disposed on the other cover plate 12. An injection hole C is disposed on one of the cover plates 12.

[0051] In some embodiments, such as Figure 1As shown, the housing 1 includes a housing body 11 and a cover plate 12. In the thickness direction of the battery, one side of the housing body 11 is open, and the cover plate 12 closes the opening. In the length direction of the battery, the positive electrode post assembly 31 and the negative electrode post assembly 32 are respectively disposed at both ends of the cover plate 12. In the length direction of the battery, the housing body 11 has recesses 11b at both ends and a protrusion 11a in the middle. The positive electrode tab 22 and the negative electrode tab 23 are respectively located within the two recesses 11b within the protrusion 11a of the cell body 21. The recesses 11b can be used to accommodate the electrode post assemblies of adjacent batteries when the batteries are assembled, improving the space utilization of the housing. When the recesses 11b are formed, transition angles are formed at both ends in the width direction (which is also the width direction of the battery). The negative electrode tab 23 needs to avoid the transition angle of the recessed part where it is located. Therefore, in the width direction of the battery, the distance D between the negative electrode tab 23 and the side wall of the recessed part should have a lower limit. If D is too large, it will cause the width of the negative electrode tab 23 to be too small. Therefore, D should also have an upper limit. Specifically, the range of D can be: 2mm≤D≤20mm. For example, D can be equal to 3mm, 5mm, 10mm, or 15mm.

[0052] In some embodiments, such as Figure 1 As shown, the battery includes an insulating protective cover, which comprises a positive electrode insulating protective cover 51 and a negative electrode insulating protective cover 52. The positive electrode insulating protective cover 51 is located inside the housing 1, specifically within the recess 11b where the positive electrode tab 22 is located, and serves to insulate between the positive electrode terminal assembly 31 and the cell body 21. The negative electrode insulating protective cover 52 is located inside the housing 1, specifically within the recess 11b where the negative electrode tab 23 is located, and serves to insulate between the negative electrode terminal assembly 32 and the cell body 21.

[0053] The positive electrode insulating protective cover 51 and the negative electrode insulating protective cover 52 have similar structures, such as Figure 5 As shown, a first support portion 5a, a tab receiving portion 5c, and a second support portion 5b are sequentially provided along the width direction of the battery. The first support portion 5a has a first sidewall A on the side near the tab receiving portion 5c, and the second support portion 5b has a second sidewall B on the side near the tab receiving portion 5c. The insulating protective cover is also equipped with a flip cover (not shown in the figure). After the tab is connected to the terminal assembly, the flip cover is closed, and the closed flip cover is engaged with the first sidewall A and the second sidewall B.

[0054] In some embodiments, at least one of the first sidewall A and the second sidewall B of the negative electrode insulating protective cover 52 is recessed in a direction away from the tab receiving portion 5c to form a cavity and / or partially provided with a hole, and a portion of the negative electrode tab 23 is located within the cavity and / or the hole. This provides sufficient accommodating space for the negative electrode tab 23, which has a larger width. The cavities formed on the first sidewall A and the second sidewall B can enhance the strength of the first sidewall A and the second sidewall B.

[0055] The above examples illustrate the principles and implementation methods of this application. The descriptions of the embodiments are merely for the purpose of helping to understand the methods and core ideas of this application. It should be noted that those skilled in the art can make various improvements and modifications to this application without departing from its principles, and these improvements and modifications also fall within the protection scope of this application.

Claims

1. A battery, characterized in that, The battery includes a cell, a casing, a positive electrode assembly, and a negative electrode assembly. The cell is located inside the casing, and the positive and negative electrode assemblies are disposed within the casing. The cell includes a cell body, a positive electrode tab, and a negative electrode tab. Along the length of the battery, the positive and negative electrode tabs extend from both ends of the cell body. The positive and negative electrode tabs are welded to the positive and negative electrode assemblies, respectively. The length of the battery is L, where L ≥ 400 mm. The thickness of the positive electrode tab is greater than the thickness of the negative electrode tab. The width of the negative electrode tab along the width of the battery is W1, and the width of the positive electrode tab along the width of the battery is W2, where W1 > W2. The width of the welding area between the negative electrode tab and the negative electrode post assembly in the width direction of the battery is W3, and the width of the welding area between the positive electrode tab and the positive electrode post assembly in the width direction of the battery is W4, 0.1≤(W1-W3) / (W2-W4)≤20; 5mm≤W1-W3≤70mm and / or 8mm≤W2-W4≤75mm; 15mm≤W1≤80mm; 13mm≤W2≤60mm.

2. The battery according to claim 1, characterized in that, The width of the cell body in the width direction of the battery is W, 0.05≤(W-W1) / (W-W2)≤0.

98.

3. The battery according to claim 2, characterized in that, 10mm≤W-W1≤100mm and / or 12mm≤W-W2≤100mm.

4. The battery according to claim 1, characterized in that, The width of the welding area between the negative electrode tab and the negative electrode post assembly in the width direction of the battery is W3, and the width of the welding area between the positive electrode tab and the positive electrode post assembly in the width direction of the battery is W4, where 1.1≤W3 / W4≤8.

5. The battery according to any one of claims 1-4, characterized in that, The housing is provided with a liquid injection hole, and the orthographic projection of the positive electrode tab on the plane where the liquid injection hole is located overlaps with the liquid injection hole at least partially, and / or, the orthographic projection of the negative electrode tab on the plane where the liquid injection hole is located overlaps with the liquid injection hole at least partially.

6. The battery according to any one of claims 1-4, characterized in that, The housing is provided with a liquid injection hole, which is located at one end from which the positive electrode tab is led out. The orthographic projection of the positive electrode tab on the plane where the liquid injection hole is located does not overlap with the liquid injection hole. The width of the cell body in the width direction of the battery is W, where 15mm≤W-W2≤100mm. In the length direction of the battery, the distance between the liquid injection hole and the cell body is L1, where 2mm≤L1≤10mm.

7. The battery according to any one of claims 1-4, characterized in that, A transition portion with radius R1 is provided between the negative electrode tab and the cell body. The welding area between the negative electrode tab and the negative electrode post assembly has a width of W3.6 mm in the width direction of the battery. 2 ≤R1×(W1-W3)≤350 mm 2 ; and / or, A transition portion with radius R2 is provided between the positive electrode tab and the cell body. The welding area between the positive electrode tab and the positive electrode post assembly has a width of W4 (10 mm) in the width direction of the battery. 2 ≤R2×(W2-W4)≤360 mm 2 .

8. The battery according to any one of claims 1-4, characterized in that, The housing includes a housing body and two cover plates. Along the length of the battery, the housing body has openings at both ends, and the two cover plates respectively close the openings at both ends. The positive electrode terminal assembly and the negative electrode terminal assembly are respectively disposed on the two cover plates.

9. The battery according to any one of claims 1-4, characterized in that, The housing includes a housing body and a cover plate. In the thickness direction of the battery, an opening is provided on one side of the housing body, and the cover plate closes the opening. In the length direction of the battery, the positive electrode post assembly and the negative electrode post assembly are respectively disposed at both ends of the cover plate. In the length direction of the battery, a recess is provided at both ends of the housing body, and the negative electrode tab is located in one of the recesses. In the width direction of the battery, the distance between the negative electrode tab and the sidewall of the recess is D, where 2mm≤D≤20mm.

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