Battery, assembling method thereof and battery pack

Abstract

The invention provides a battery, an assembling method thereof and a battery pack, the battery comprises a shell, and the shell is provided with an opening end; the top cover assembly comprises a cover plate, and the cover plate is connected to the opening end of the shell; the pole piece assembly is accommodated in the inner cavity of the shell; wherein an interval is arranged between the top end face of the pole piece assembly and the opening end of the shell, the height of the interval is set to be Gap A, and Gap A is larger than or equal to 0.725 mm and smaller than or equal to 3.94 mm.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a battery, its assembly method, and a battery pack. Background Technology

[0002] Cylindrical or prismatic batteries consist of a casing and a top cover welded to one end of the casing. The casing and top cover are typically connected by laser welding. The electrode assembly is housed within the inner cavity of the casing. In related technologies, the top cover and casing are generally made of the same type of high-melting-point metal material, such as SUS304 stainless steel or SPCC nickel-plated steel. The melting point of these two materials is above 1500℃. Another type of casing material is 3003 series aluminum or 7 series aluminum, which have a melting point of 600℃ to 800℃. The melting point of the separator in the electrode assembly is generally within 120℃ to 360℃. During the battery manufacturing process, the electrode assembly is usually fixed in the inner cavity of the casing, and the top cover is then sealed at the opening of the casing by laser welding. However, the high temperature of the laser used in the laser welding process between the casing and the top cover can corrode the low-melting-point separator and insulating components. When the high temperature of the laser corrodes the separator, it causes the separator to shrink, which in turn leads to insulation failure between the positive and negative electrodes. Summary of the Invention

[0003] The embodiments of the present invention provide a battery and its assembly method and battery pack, which can improve the technical problem of diaphragm shrinkage caused by high-energy laser used in welding the casing and top cover.

[0004] In a first aspect, embodiments of the present invention provide a battery, the battery comprising:

[0005] A housing having an open end;

[0006] A top cover assembly, the top cover assembly including a cover plate connected to an opening end of the housing;

[0007] An electrode assembly, wherein the electrode assembly is housed within the inner cavity of the housing;

[0008] The electrode assembly has a gap between its top surface and the opening of the housing, with the height of the gap being Gap A, where 0.725mm ≤ Gap A ≤ 3.94mm.

[0009] In one embodiment, a welding fusion zone is provided between the housing and the cover plate. The welding fusion zone extends along the height direction of the housing by a height of d1. The thickness of the housing is t. The ratio of d1 to t is 1.5 to 1.8, and d1 < Gap A.

[0010] In one embodiment, the device further includes a heat insulation layer disposed on the inner wall of the housing, the heat insulation layer being disposed outside the welding fusion zone, a portion of the heat insulation layer being located between the electrode assembly and the housing, and another portion of the heat insulation layer being located within the gap.

[0011] In one embodiment, the insulation layer extends at a height of L1 along the height direction of the shell, where 1.5mm ≤ L1 ≤ 2.5mm.

[0012] In one embodiment, the projection height of the insulation layer on the electrode assembly is d2, and the difference between L1 and d2 is not less than 0.5;

[0013] And / or, 1.0mm≤d2≤2.0mm.

[0014] In one embodiment, the thickness of the insulation layer is t1, where 20μm≤t1≤35μm.

[0015] In one embodiment, Gap A is greater than L1-d2+d1, or Gap A = L1-d2+d1+1mm.

[0016] In one embodiment, the thermal conductivity of the material used to form the insulation layer is not greater than 0.064 W / (m·℃), and / or the material used to form the insulation layer includes EPDM rubber and nanoporous silicon material.

[0017] In one embodiment, the battery includes a first negative current collector and a positive current collector electrically connected to the top cover assembly. The electrode assembly includes a positive electrode and a negative electrode. One end of the positive electrode is connected to a positive electrode tab, and one end of the negative electrode is connected to a negative electrode tab. The positive electrode tab is welded to the positive current collector, and a portion of the negative electrode tab is welded to the first negative current collector.

[0018] The top cover assembly includes a first insulating member, a portion of which is disposed between the cover plate and the positive current collector, and another portion of which is used to support the first negative current collector. The first negative current collector, the first insulating member, and the positive current collector are arranged sequentially along the radial direction of the housing towards the central axis of the housing, or the positive current collector, the first insulating member, and the first negative current collector are arranged sequentially along the radial direction of the housing towards the central axis of the housing.

[0019] In one embodiment, the battery further includes a second negative current collector electrically connected to the bottom end of the housing, and another portion of the negative electrode tab is welded to the second negative current collector.

[0020] In one embodiment, the top cover assembly includes a positive electrode post and an injection hole disposed on the positive electrode post. The positive electrode post is welded to the positive electrode manifold. The top cover assembly also includes a sealing post for sealing the injection hole, and the sealing post is welded to the positive electrode post.

[0021] Secondly, embodiments of the present invention provide a battery assembly method, the assembly method comprising:

[0022] An insulation layer is coated on the inner wall of the housing, and the insulation layer is dried.

[0023] An electrode assembly is prepared by welding the positive electrode tab of the electrode assembly to the positive current collector and welding the negative electrode tab of the electrode assembly to the negative current collector, thus forming the assembly to be assembled 1.

[0024] Place the component to be assembled, 1, into the interior of the housing with the output end facing upwards;

[0025] The positive current collector is welded to the positive electrode post, and the negative current collector is welded to the cover plate or the housing; or, the negative current collector is welded to the negative electrode post, and the positive current collector is welded to the cover plate or the housing.

[0026] The cover plate is welded onto the housing.

[0027] The electrolyte is injected into the interior of the housing through the injection hole on the top cover assembly for formation. After formation, the sealing post is welded to the top cover assembly.

[0028] Thirdly, embodiments of the present invention provide a battery pack, wherein the battery pack comprises the aforementioned plurality of batteries, or the battery pack is prepared by the aforementioned assembly method to form the batteries.

[0029] The beneficial effects of the embodiments of the present invention are as follows:

[0030] In embodiments of the present invention, by controlling the gap A between the top surface of the electrode assembly and the opening end of the housing to be ≥0.725mm, the high temperature used during the welding process between the housing and the cover plate can be used to prevent the diaphragm in the electrode assembly from shrinking. Furthermore, by controlling the gap A between the electrode assembly and the opening end of the housing to be ≤3.45mm, the gap A between the electrode assembly and the opening end of the housing can be prevented from being too large, which would result in a low capacity utilization rate inside the battery. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a cross-sectional structural diagram of a battery provided in an embodiment of the present invention;

[0033] Figure 2 This is a cross-sectional structural diagram of the battery after the top cover assembly has been removed, according to an embodiment of the present invention.

[0034] Figure 3 yes Figure 2 A magnified view of a portion of the image;

[0035] Figure 4 yes Figure 3 A magnified view of a portion of the image;

[0036] Figure 5 This is a cross-sectional structural diagram of the top cover assembly of the battery provided in the comparative example of the present invention before use.

[0037] Figure 6 This is a cross-sectional structural diagram of the top cover assembly of the battery provided in the comparative example of the present invention after use.

[0038] Figure 7 yes Figure 1 A magnified view of a portion of the image;

[0039] Figure 8 This is a top view of the battery structure provided in an embodiment of the present invention;

[0040] Icon labels:

[0041] 100. Battery; 110. Casing; 111. Open end; 112. Bottom end

[0042] 10. Top cover assembly; 11. Cover plate; 12. Positive electrode post; 13. First insulating component; 14. Sealing element; 15. Explosion-proof valve; 16. Injection hole; 17. Sealing post; 18. Groove portion;

[0043] 20. Electrode assembly; 210. Top surface of electrode assembly; 21. Separator; 22. Positive electrode; 221. Positive electrode tab; 23. Negative electrode; 231. Negative electrode tab;

[0044] 30. Second insulating component;

[0045] 41. Positive current collector; 42. First negative current collector; 43. Second negative current collector;

[0046] 50. Insulation layer; 51. Welding fusion zone;

[0047] 60. External positive electrode welding area; 61. External negative electrode welding area. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Furthermore, it should be understood that the specific embodiments described herein are only for illustration and explanation of the present invention and are not intended to limit the present invention. In the present invention, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in actual use or operation, specifically the drawing directions in the accompanying drawings; while "inner" and "outer" refer to the outline of the device.

[0049] Embodiments of this application provide a battery 100, which can be a cylindrical battery or a prismatic battery, such as... Figures 1 to 4 As shown, the battery 100 includes a housing 110, a top cover assembly 10, and an electrode assembly 20. The housing 110 is constructed as a hollow structure with one end open. The electrode assembly 20 is housed in the inner cavity of the housing 110, and the top cover assembly 10 is connected to the open end of the housing 110.

[0050] like Figure 3 As shown, the electrode assembly 20 includes a positive electrode 22, a negative electrode 23, and a separator 21 for separating the positive electrode 22 and the negative electrode 23. In a cylindrical battery, the electrode assembly 20 can be configured to form a wound assembly structure by winding it along its central axis. In a prismatic battery, the electrode assembly 20 can be configured to form a stacked assembly structure by stacking layers along the height direction of the housing 110.

[0051] The top cover assembly 10 includes a cover plate 11, a terminal post, and an insulating component. The terminal post is fixed on the cover plate 11, and one end of the terminal post passes through and extends out of the cover plate 11. The top cover assembly 10 may include at least one of a positive terminal post 12 and a negative terminal post. The battery 100 also has multiple current collectors inside, including a positive current collector 41 and a negative current collector. The end of the positive electrode 22 is connected to a positive electrode tab 221, which is folded and connected to the positive current collector 41. The end of the negative electrode 23 is connected to a negative electrode tab 231, which is folded and connected to the negative current collector.

[0052] In one example, the top cover assembly 10 includes a positive terminal 12, with a positive current collector 41 further welded to the positive terminal 12, and a negative current collector further welded to the bottom end 112 of the housing 110 or the cover plate 11. Alternatively, the top cover assembly 10 includes a negative terminal, with a negative current collector welded to the negative terminal, and a positive current collector further welded to the bottom end 112 of the housing 110 or the cover plate 11. In other alternative examples, the top cover assembly 10 includes a positive terminal 12 and a negative terminal, with the positive current collector 41 welded to the positive terminal 12 and the negative current collector welded to the negative terminal.

[0053] In related technologies, the cover plate 11 and the housing 110 are connected in a fully sealed manner by laser welding. The cover plate 11 and the housing 110 are made of the same material, such as SUS304 stainless steel, SPCC nickel-plated steel, 3003 series aluminum, or 7 series aluminum. The melting point of the above steels is above 1500°C, and the melting point of aluminum is 120°C to 360°C. The diaphragm 21 of the electrode assembly 20 housed inside the housing 110 is usually made of polymer material. For example, PP diaphragm 21 or PE diaphragm 21, wherein the melting point of single-layer PP diaphragm 21 is 160℃~165℃, and the melting point of single-layer PE diaphragm 21 is 130℃~135℃. Therefore, during the laser welding process of cover plate 11 and housing 110, the high temperature generated by the laser will cause thermal corrosion of diaphragm 21 in electrode assembly 20 near cover plate 11, which will cause diaphragm 21 to shrink, thereby causing positive electrode 22 and negative electrode 23 at the shrinkage point of diaphragm 21 to come into contact and short circuit.

[0054] To address the aforementioned issues, the structure of the battery 100 is improved in the embodiments of this application, thereby ensuring a suitable distance between the top surface 210 of the electrode assembly 20 and the welding connection end of the housing 110 and the cover plate 11. During the laser welding process between the housing 110 and the cover plate 11, the high temperature generated by the laser makes it difficult for the diaphragm 21 in the electrode assembly 20 to undergo thermal corrosion, thus preventing the diaphragm 21 from shrinking.

[0055] refer to Figure 1 As shown, the distance between the top end of the electrode assembly 20 and the opening end 111 of the housing 110 is Gap A, where 0.725mm ≤ Gap A ≤ 3.45mm. The value of Gap A can be 0.8mm, 1.0mm, 1.2mm, 1.4mm, 1.6mm, 1.8mm, 2.0mm, 2.2mm, 2.4mm, 2.6mm, 2.8mm, 3.0mm, 3.2mm, 3.4mm, or any value between any two of the above values, or a range between any two of the above values.

[0056] Further reference Figure 5 and Figure 6 As shown, the inventors discovered through research that when the distance Gap A between the top of the electrode assembly 20 and the opening 111 of the housing 110 is set to 0.46 mm, and the shrinkage distance d0 of the diaphragm 21 in the electrode assembly 20 is measured to be 0.23 mm, therefore, under the premise that the energy of the laser used for laser welding between the cover plate 11 and the housing 110 remains constant, setting the distance Gap A between the top of the electrode assembly 20 and the opening 111 of the housing 110 to be greater than 0.7 mm ensures that the electrode assembly 20 is located outside the high-temperature zone of the laser during the laser welding process between the cover plate 11 and the housing 110, and thus the high temperature of the laser will not affect the electrode assembly 20. Furthermore, the inventors discovered through research that when the distance Gap A between the top of the electrode assembly 20 and the opening 111 of the housing 110 is set to equal to 0.725 mm, the diaphragm 21 of the electrode assembly 20 will not be affected by the high temperature during the laser welding process at all.

[0057] Considering that an excessively large gap A between the top of the electrode assembly 20 and the opening 111 of the casing 110 would result in low internal space utilization of the battery 100, the internal space utilization of the battery 100 can be defined as the space occupied by the electrode assembly 20 inside the battery 100. As the active material component of the battery 100, the larger the space occupied by the electrode assembly 20, the greater the capacity of the battery 100 of the same volume. In a preferred embodiment, the gap A between the top of the electrode assembly 20 and the opening 111 of the casing 110 is set to no more than 3.45 mm. Taking an 18450 battery as an example, when the gap A is set to 4 mm, compared to a gap A set to 3 mm, the internal space utilization of the battery 100 decreases by 2%.

[0058] It should be noted that the above-mentioned method for measuring the gap A is as follows: when the starting point of the weld between the cover plate 11 and the housing 110 is the top of the housing 110, the gap A is the distance from the opening end 111 of the housing 110 downwards to the top surface 210 of the electrode assembly 20. When the starting point of the weld between the cover plate 11 and the housing 110 is a certain distance from the top surface of the housing 110, the gap A is the distance from the starting point of the weld between the housing 110 and the cover plate 11 downwards to the top surface 210 of the electrode assembly 20. The starting point of the weld between the housing 110 and the cover plate 11 is the first weld mark formed between the housing 110 and the cover plate 11, and the first weld mark is set to be the weld mark closest to the top surface of the housing 110.

[0059] Further reference Figures 1 to 4As shown, a welding fusion zone 51 is formed between the housing 110 and the cover plate 11. The welding fusion zone 51 extends to a height d1 along the height direction of the housing 110, and the thickness of the housing 110 is t. The ratio between the height d1 of the welding fusion zone 51 and the thickness t of the housing 110 is 1.1 to 1.8 (inclusive of the endpoint value), and the welding fusion zone 51 is located within the region corresponding to Gap A, i.e., d1 < Gap A. Further, the ratio of the height d1 of the welding fusion zone 51 to the thickness t can be 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, or any value between any two of the above values, or a range between any two of the above values.

[0060] Wherein, the height direction of the shell 110 is as follows Figure 1 In the Y direction shown, the housing 110 includes an open end 111 and a bottom end 112 disposed opposite to each other. The line connecting the shortest distance between the open end 111 and the bottom end 112 is parallel to the height direction of the housing 110. A cover plate 11 is connected to the open end 111 of the housing 110. A terminal post is usually disposed on the cover plate 11 or the bottom end 112 of the housing 110, wherein the terminal post can be a positive terminal post or a negative terminal post. In a cylindrical battery, the height direction of the housing 110 coincides with the longitudinal direction of the electrode assembly 20.

[0061] Based on the physical properties of the materials of the housing 110 and the cover plate 11, laser welding is performed between the housing 110 and the cover plate 11. The energy used by the laser is configured to melt the weld joint between the housing 110 and the cover plate 11. The housing 110 and the cover plate 11 can be made of the same metal material. The thermal conductivity of the metal material is isotropic. Therefore, during the fusion process of the housing 110 and the cover plate 11, the height d1 of the welded fusion zone 51 of the housing 110 is not less than its corresponding thickness t in the thickness and height directions of the housing 110. When the ratio between the height d1 of the welded fusion zone 51 and the thickness t of the housing 110 is less than 1.1, the height of the welded fusion zone 51 will be insufficient, resulting in insufficient bonding strength between the housing 110 and the top cover assembly 10. When the ratio between the height d1 of the welded fusion zone 51 and the thickness t of the housing 110 is greater than 1.8, the difference between Gap A and d1 will be small, which is not conducive to the protection of the diaphragm 21 in the electrode assembly 20.

[0062] The thickness of the casing 110 is defined as the wall thickness of the casing 110, and t is set to 0.25mm to 0.8mm. In specific implementations, t can be set to 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, or any value between any two of the above, or a range between any two of the above values. When the thickness of the casing 110 is less than 0.25mm, the casing 110 will not be strong enough, making it easy to be punctured or deformed, which in turn will result in insufficient strength of the battery 100. When the thickness of the casing 110 is greater than 0.8mm, the weight of the battery 100 will increase. When the volume of the battery 100 remains unchanged, the internal volume of the battery 100 will be compressed, which is detrimental to the lightweight design of the battery 100.

[0063] Further reference Figure 3 and Figure 4 As shown, a heat insulation layer 50 is further provided on the inner wall of the housing 110. This heat insulation layer 50 is offset from the welding fusion area 51 to avoid affecting the welding between the housing 110 and the cover plate 11. A portion of the heat insulation layer 50 is located between the electrode assembly 20 and the housing 110, and another portion of the heat insulation layer 50 is located within the aforementioned gap A. This heat insulation layer 50 is used to further isolate the heat from the welding fusion area 51 from being transferred to the outer diaphragm 21 of the electrode assembly 20, thereby causing the outer diaphragm 21 of the electrode assembly 20 to be thermally corroded and shrink.

[0064] In a preferred embodiment, the insulation layer 50 extends to a height L1 along the height direction of the shell 110, where 1.5mm ≤ L1 ≤ 2.5mm. In a specific embodiment, the height L1 of the insulation layer 50 can be 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2.0mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, or any value between any two of the above, or a range between any two of the above values.

[0065] Further reference Figure 3 and Figure 4As shown, the height of the separator 21 in the core assembly is greater than the height of the negative electrode 23, and the height of the negative electrode 23 is greater than the height of the positive electrode 22. The insulation layer 50 is configured to cover the section of the separator 21 that extends beyond the negative electrode 23. The height of the separator 21 extending beyond the negative electrode 23 is typically set to 1.2mm to 1.75mm, therefore the height L1 of the insulation layer 50 is set to 1.5mm to 2.5mm. When the height L1 of the insulation layer 50 is less than 1.5mm, the insulation layer 50 cannot provide effective thermal insulation protection for the separator 21. When the height L1 of the insulation layer 50 is greater than 2.5mm, the insulation layer 50 will extend into the welding fusion area 51 between the housing 110 and the cover plate 11, thereby affecting the welding between the housing 110 and the cover plate 11.

[0066] The insulation layer 50 is preferably made of an elastic material with low thermal conductivity and corrosion resistance, and the thermal conductivity of the material used to make the insulation layer 50 is not greater than 0.064 W / (m·℃). Suitable materials include EPDM rubber with added nanoporous silica material, wherein the nanoporous silica material is used as a filler with low thermal conductivity to reduce the thermal conductivity of the insulation layer 50, and EPDM rubber has excellent corrosion resistance and reinforcing properties.

[0067] The projected height of the insulation layer 50 on the electrode assembly 20 is d2, and the difference between L1 and d2 is not less than 0.5, and / or 1.0mm≤d2≤2.0mm. The difference between L1 and d2 is the distance by which the top of the insulation layer 50 extends beyond the top of the electrode assembly 20. Therefore, in specific implementations, the projected height d2 of the insulation layer 50 on the electrode assembly 20 can be 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, or any value between any two of the above, or a range between any two of the above values. The projected height d2 of the insulation layer 50 on the electrode assembly 20 is the height d2 of the insulation layer 50 coated on the inner side of the electrode assembly 20. Therefore, when the projected height d2 of the insulation layer 50 on the electrode assembly 20 is less than 1.0 mm, a portion of the outer separator 21 of the electrode assembly 20 is still within the range of heat radiation from the shell 110 near the welding fusion area 51. The inner side of this portion of the outer separator 21 is not insulated by the insulation layer 50, which will cause this portion of the separator 21 to be easily corroded and shrink. When the projected height d2 of the insulation layer 50 on the electrode assembly 20 is greater than 2.0 mm, it will lead to excessive use of the insulation layer 50 material, which is not conducive to saving the cost of the battery 100.

[0068] In a preferred embodiment, the thickness t1 of the insulation layer 50 is greater than 20 μm and less than 100 μm. Further, the thickness t1 of the insulation layer 50 is 20 μm to 35 μm (inclusive). In specific embodiments, the thickness t1 of the insulation layer 50 can be 22 μm, 24 μm, 26 μm, 28 μm, 30 μm, 32 μm, 34 μm, or any value between any two of the above values, or a range between any two of the above values. When the thickness t1 of the insulation layer 50 is less than 20 μm, the insulation capacity of the insulation layer 50 will be insufficient, resulting in a portion of the diaphragm 21 still being corroded by the high-energy laser in the welding fusion zone 51, causing the diaphragm 21 to shrink. Furthermore, when the thickness t1 of the insulation layer 50 is less than 20 μm, pores are easily formed inside the insulation layer 50. The heat in the welding fusion zone 51 will further diffuse through the pores to the diaphragm 21 of the core assembly, which will cause the diaphragm 21 to shrink. When the thickness t1 of the insulation layer 50 is greater than 35 μm, the insulation layer 50 will occupy more of the internal space of the housing 110, which will reduce the utilization rate of the internal space of the housing 110.

[0069] The inventors discovered through research that Gap A = L1 - d2 + d1 + 1mm. When Gap A satisfies the above relationship with L1, d2, and d1, the separator 21 in the electrode assembly 20 inside the battery 100 will not be corroded by the high-power laser used during the welding process of the casing 110 and the top cover assembly 10, and the internal space of the battery 100 will not be wasted. Furthermore, the difference between Gap A and L1 - d2 + d1 is mainly related to the width tolerance range of the insulation layer 50. The insulation layer 50 is formed by processing the inner cylindrical wall of the cylindrical battery 100. The insulation layer 50 is set as a UV liquid coating layer, so its tolerance range is relatively large, which is ±0.5mm, and the tolerance width of the insulation layer 50 is 1mm.

[0070] The specific values ​​for Gap A, the thickness t of the shell 110, the height d1 of the welding fusion zone 51, the height L1 of the insulation layer 50, and the projection height d2 of the insulation layer 50 on the electrode assembly 20 can be referred to the eight specific embodiments provided in Table 1 below:

[0071] Table 1. Parameters related to the welding fusion zone 51 between the shell 110 and the cover plate 11, and the insulation layer 50.

[0072] Serial Number t(mm) L1(mm) d1(mm) d2(mm) Gap A (mm) 1 0.25 1.5 0.45 1 1.95 2 0.25 2.5 0.45 1 2.45 3 0.8 1.5 1.44 1 2.94 4 0.8 2.5 1.44 2 2.94 5 0.25 1.5 0.375 1 1.875 6 0.25 2.5 0.375 2 1.875 7 0.8 1.5 1.44 1 2.94 8 0.8 2.5 1.44 1 3.94

[0073] Analysis of the data in Table 1 shows that the ratio between the height d1 of the welding fusion zone 51 and the thickness t of the shell 110 is 1.1 to 1.8, the height L1 of the insulation layer 50 is set to 1.5 mm to 2.5 mm, the difference between the height L1 of the insulation layer 50 and the projection height d2 of the insulation layer 50 on the electrode assembly 20 is not less than 0.5 mm, and d2 is set to 1 mm to 2 mm. Gap A satisfies Gap A = L1 - d2 + d1 + 1 mm, and Gap A is set to between 0.725 mm and 3.94 mm.

[0074] By testing and analyzing the batteries 100 of the various embodiments in Table 1, when the welding fusion area 51 of the housing 110 and the top cover assembly 10 and the heat insulation layer 50 in the battery 100 meet the requirements of Table 1 above, the diaphragm 21 in the electrode assembly 20 will not be affected by the high-energy laser used in the laser welding process of the housing 110 and the top cover assembly 10.

[0075] The top cover assembly 10 typically includes a cover plate 11, an electrode post, and a plastic insulating component. A portion of the plastic insulating component is disposed between the cover plate 11 and the electrode post. In related technologies, the plastic insulating component disposed near the electrode post is usually close to the welding fusion area 51 between the housing 110 and the cover plate 11. The melting point of the insulating component is usually 120°C to 360°C. Therefore, the high-energy laser used in the welding fusion area 51 will further corrode the insulating component near the electrode post. The insulating component will melt and form an evaporating substance. This evaporating substance will further remain in the weld gap, causing holes in the weld area and thus forming a leakage channel.

[0076] To address the aforementioned issues, the structure of the top cover assembly 10 and the assembly process of the battery 100 are further optimized in the embodiments of this application, thereby avoiding the problem of leakage channels being formed on the top cover assembly 10 due to corrosion of the insulating parts by the high-energy laser used for welding.

[0077] Further reference Figure 1 and Figure 8 As shown, a positive electrode post 12 is provided on the top cover assembly 10, and the electrode assembly 20 includes positive electrode plates 22 and negative electrode plates 23 arranged at intervals. One end of the positive electrode plate 22 is connected to a positive electrode tab 221, and one end of the negative electrode plate 23 is connected to a negative electrode tab 231. The positive electrode tab 221 is folded and welded to the positive electrode current collector 41. The positive electrode current collector 41 is welded to the positive electrode post 12. The negative electrode tab 231 is folded and welded to the negative electrode current collector. The negative electrode current collector is welded to the bottom end 112 of the housing 110 or the cover plate 11.

[0078] In a preferred embodiment, both the positive and negative output terminals of the battery 100 are located on the top cover assembly 10. Specifically, the negative current collector includes a first negative current collector 42 and a second negative current collector 43. The first negative current collector 42 is welded to the cover plate 11, and the second negative current collector 43 is welded to the bottom end 112 of the housing 110. A portion of the negative electrode tabs 231 are welded to the first negative current collector 42, and another portion of the negative electrode tabs 231 are welded to the second negative current collector 43. A groove 18 is provided on the cover plate 11, and the bottom surface of the groove 18 is welded to the first negative current collector 42. By setting the negative current collector in two parts, the distance between the first negative current collector 42 and the welding fusion area 51 can be further increased, thereby avoiding high-temperature corrosion of the first insulating component 13 near the first negative current collector 42 by the high-energy laser inside the welding fusion area 51.

[0079] Further reference Figure 1 and Figure 8 As shown, the top cover assembly 10 includes a positive electrode post 12, which is disposed on the central axis of the battery 100. A positive current collector 41 is welded to the positive electrode post 12, and a first negative current collector 42 is welded to the cover plate 11.

[0080] The top cover assembly 10 includes a first insulating member 13, which is made of plastic material. A portion of the first insulating member 13 is disposed between the cover plate 11 and the positive current collector 41, and another portion of the first insulating member 13 supports the first negative current collector 42. The first negative current collector 42, the first insulating member 13, and the positive current collector 41 are sequentially arranged along the radial direction of the housing 110 toward the central axis of the housing 110. Since the first insulating member 13 is located away from the welding fusion area 51 between the housing 110 and the cover plate 11, the high-energy laser used during the welding process between the housing 110 and the cover plate 11 will not cause the first insulating member 13 to melt and evaporate, thereby preventing the evaporated material formed by the melting and evaporation of the first insulating member 13 from remaining in the weld gap and forming a leakage channel. Furthermore, a gap is provided between the first negative current collector 42 and the inner wall of the housing 110 for further heat insulation.

[0081] A second insulating element 30 is also provided at the bottom 112 of the housing 110. The second insulating element 30 is made of plastic material and is used to further support and fix the second negative current collector 43.

[0082] In alternative examples, the top cover assembly 10 includes a negative terminal post disposed on the central axis of the battery 100, a negative current collector plate welded to the negative terminal post, a positive current collector plate 41 welded to the cover plate 11, a portion of a first insulating member 13 disposed between the cover plate 11 and the negative current collector plate, and another portion of the first insulating member 13 used to support the positive current collector plate 41. The positive current collector plate 41, the first insulating member 13, and the negative current collector plate are sequentially arranged along the radial direction of the housing 110 from the outer side of the housing 110 toward the central axis of the housing 110.

[0083] In the above-described battery 100 structure, both the first insulating member 13 and the second insulating member 30 are located away from the welding fusion area 51 between the housing 110 and the cover plate 11. Specifically, the housing 110, the heat insulation layer 50, the negative electrode current collector and the first insulating member 13 are arranged sequentially along the radial direction of the housing 110 toward the central axis of the housing 110. Therefore, the high temperature generated in the welding fusion area 51 between the housing 110 and the cover plate 11 will not be conducted to the first insulating member 13, thereby effectively preventing the heat of the welding fusion area 51 from being transferred to the first insulating member 13.

[0084] An external positive electrode welding area 60 and an external negative electrode welding area 61 are further provided on the outer surface of the top cover assembly 10. The external negative electrode welding area 61 is used for connecting a connecting piece or connecting circuit to the negative terminal post or cover plate 11 of the battery 100, and the external positive electrode welding area 60 is used for connecting a connecting piece or connecting circuit to the positive terminal post 12 or cover plate 11 of the battery 100. Figure 7 As shown, the external positive electrode welding area 60 is located in the central region of the battery 100, and the external negative electrode welding area 61 is located on the outer periphery of the external positive electrode welding area 60.

[0085] A sealing element 14 is also provided between the cover plate 11 and the positive electrode post 12. The sealing element 14 is preferably made of silicone material. The sealing element 14 allows the positive electrode post 12 to be interference-fitted into the fixing hole of the cover plate 11. Furthermore, the sealing element 14 is also used to insulate the cover plate 11 from the positive electrode post 12.

[0086] Furthermore, the top cover assembly 10 also includes an explosion-proof valve 15, which is configured to be formed by a portion of the cover plate 11. The explosion-proof valve 15 includes a serration on the cover plate 11, the wall of which is located will be damaged when subjected to pressure inside the battery 100, thereby causing a pressure relief port to be formed in a portion of the cover plate 11.

[0087] A liquid injection hole 16 is provided on the positive electrode post 12, and a sealing post 17 is provided to seal the liquid injection hole 16. The sealing post 17 is laser welded into the liquid injection hole 16 of the positive electrode post 12. A through hole is further provided on the positive electrode current collector 41, which is positioned opposite to the liquid injection hole 16 on the positive electrode post 12.

[0088] This application provides a method for manufacturing the battery 100 described above, the method comprising:

[0089] The first step is to coat the inner wall of the housing 110 with an insulation layer 50 and then dry it. The insulation layer 50 is coated according to the requirements of the above embodiment. Specifically, the insulation layer 50 is offset from the welding fusion area 51, and a portion of the insulation layer 50 is located between the electrode assembly 20 and the housing 110, while another portion is located within the aforementioned gap A. Suitable materials for forming the insulation layer 50 include EPDM rubber with added nanoporous silica material. The insulation layer prepared using EPDM rubber as the substrate and nanoporous silica material as the filler can be directly coated onto the inner wall of the housing using processes such as spraying, brushing, or centrifugation, and then cured by heating.

[0090] The second step involves folding the positive electrode tab 221 of the electrode assembly 20 and welding it to the positive current collector 41, and folding the negative electrode tab 231 of the electrode assembly 20 and welding it to the negative current collector. The positive electrode tab 221 is configured to be folded towards the direction close to the top cover assembly 10. The positive electrode tab 221 and the positive current collector 41 can be welded by resistance welding or laser welding. A portion of the negative electrode tab 231 is folded towards the direction close to the top cover assembly 10, and this portion of the negative electrode tab 231 is welded to the first negative current collector 42. Another portion of the negative electrode tab 231 is folded towards the direction close to the bottom end 112 of the housing 110, and this portion of the negative electrode tab 231 is welded to the second negative current collector 43.

[0091] The third step is to place the electrode assembly 20 into the inner cavity of the housing 110 with the output end facing upwards. The output end of the electrode assembly 20 includes a positive electrode tab 221 and a negative electrode tab 231. In the above embodiment, a positive electrode post 12 is provided on the top cover assembly 10, so the end of the electrode assembly 20 with the positive electrode tab 221 corresponds to the top opening end of the housing 110.

[0092] The fourth step is to weld the positive current collector 41 to the positive terminal 12 and to weld the negative current collector to the housing 110 and / or the cover plate 11. Preferably, the positive current collector 41 and the positive terminal 12 are welded by laser welding. In the above embodiment, the negative current collector includes a first negative current collector 42 and a second negative current collector 43. The first negative current collector 42 is welded to the cover plate 11 and the second negative current collector 43 is welded to the bottom of the housing 110.

[0093] The fifth step is to inject the electrolyte into the battery 100 through the injection hole 16 for formation; the electrolyte is injected through the injection hole 16 on the positive electrode post 12 using an injection tool, and the electrolyte further enters the electrode assembly 20 through the through hole on the positive electrode current collector 41.

[0094] The sixth step is to weld and seal the liquid injection hole 16 of the top cover assembly 10 using a sealing post 17; the welding method of the sealing post 17 and the positive electrode post 12 on the top cover assembly 10 is preferably laser welding.

[0095] The seventh step is to encapsulate the battery 100. The specific encapsulation method is selected according to the type of the final formed battery 100. For example, cylindrical and prismatic batteries are mostly encapsulated with hard shells, while pouch batteries are mostly encapsulated with aluminum-plastic film.

[0096] Because an insulating layer 50 is coated on the inner wall of the casing 110 of the battery 100, the separator 21 located inside the insulating layer 50 can be effectively protected from corrosion by the high temperature energy generated by the welding fusion zone 51. Furthermore, after welding the casing 110 to the cover plate 11, electrolyte is injected into the interior of the battery 100, and finally the top cover assembly 10 is sealed, thereby effectively improving the sealing performance of the battery 100.

[0097] The present invention also provides a battery pack, the battery pack including a housing and a plurality of batteries disposed inside the housing, the plurality of batteries being configured to be connected in series, in parallel or in a mixed configuration to meet the capacity requirements of the battery pack, the battery pack being used to power electric vehicles or power tools.

[0098] The embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A battery, characterized in that, include: A housing having an open end; An electrode assembly, wherein the electrode assembly is housed within the inner cavity of the housing; A top cover assembly, the top cover assembly including a cover plate, the cover plate being welded to the opening end of the housing to cover the electrode assembly; The electrode assembly has a gap between its top surface and the opening of the housing, with the height of the gap being Gap A, where 0.725mm ≤ Gap A ≤ 3.94mm.

2. The battery according to claim 1, characterized in that, The shell is provided with a welding fusion zone for welding the shell to the cover plate. The height of the welding fusion zone along the height direction of the shell is d1, the thickness of the shell is t, the ratio of d1 to t is 1.5 to 1.8, and / or d1 < Gap A.

3. The battery according to claim 2, characterized in that, It also includes a heat insulation layer disposed on the inner wall of the housing, the heat insulation layer being disposed outside the welding fusion zone, a portion of the heat insulation layer being located between the electrode assembly and the housing, and another portion of the heat insulation layer being located within the gap.

4. The battery according to claim 3, characterized in that, The insulation layer extends at a height of L1 along the height direction of the shell, where 1.5mm ≤ L1 ≤ 2.5mm.

5. The battery according to claim 4, characterized in that, The height of the insulation layer projected onto the electrode assembly is d2, and the difference between L1 and d2 is not less than 0.

5. And / or, 1.0mm≤d2≤2.0mm.

6. The battery according to claim 3, characterized in that, The thickness of the insulation layer is t1, where 20μm≤t1≤35μm.

7. The battery according to claim 5, characterized in that, Gap A is greater than L1-d2+d1, or Gap A = L1-d2+d1+1mm.

8. The battery according to claim 3, characterized in that, The thermal conductivity of the material used to form the insulation layer is not greater than 0.064 W / (m·℃), and / or the material used to form the insulation layer includes EPDM rubber and nanoporous silicon material.

9. The battery according to any one of claims 1-8, characterized in that, The battery includes a first negative current collector and a positive current collector electrically connected to the top cover assembly. The electrode assembly includes a positive electrode and a negative electrode. One end of the positive electrode is connected to a positive electrode tab, and one end of the negative electrode is connected to a negative electrode tab. The positive electrode tab is welded to the positive current collector, and a portion of the negative electrode tab is welded to the first negative current collector. The top cover assembly includes a first insulating member, a portion of which is disposed between the cover plate and the positive current collector, and another portion of which is used to support the first negative current collector. The first negative current collector, the first insulating member, and the positive current collector are arranged sequentially along the radial direction of the housing from the outer side of the housing to the central axis of the housing, or the positive current collector, the first insulating member, and the first negative current collector are arranged sequentially along the radial direction of the housing from the outer side of the housing to the central axis of the housing.

10. The battery according to claim 9, characterized in that, The battery also includes a second negative current collector electrically connected to the bottom of the casing, and another portion of the negative electrode tab is welded to the second negative current collector.

11. The battery according to claim 9, characterized in that, The top cover assembly includes a positive electrode post with a liquid injection hole. The positive electrode post is welded to the positive current collector. The top cover assembly also includes a sealing post for sealing the liquid injection hole, which is welded to the positive electrode post.

12. A method for assembling the battery according to claim 1, characterized in that, The assembly method includes: An insulation layer is coated on the inner wall of the housing, and the insulation layer is dried. An electrode assembly is prepared by welding the positive electrode tab of the electrode assembly to the positive current collector and welding the negative electrode tab of the electrode assembly to the negative current collector, thus forming the assembly to be assembled 1. Place the component to be assembled, 1, into the interior of the housing with the output end facing upwards; The positive current collector is welded to the positive electrode post, and the negative current collector is welded to the cover plate or the housing; or, the negative current collector is welded to the negative electrode post, and the positive current collector is welded to the cover plate or the housing. The cover plate is welded onto the housing. The electrolyte is injected into the interior of the housing through the injection hole on the top cover assembly for formation. After formation, the sealing post is welded to the top cover assembly.

13. A battery pack, characterized in that, The battery pack includes a plurality of batteries as described in any one of claims 1-11, or includes batteries prepared using the assembly method of the battery as described in claim 12.

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