Battery and battery pack

Abstract

The utility model provides a battery 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] The utility model relates to the technical field of batteries, and in particular to a battery and a battery pack. Background Art

[0002] A cylindrical battery or a square battery includes a shell and a top cover welded to one end of the shell, wherein the shell and the top cover are usually connected by laser welding, and the pole piece assembly is accommodated in the inner cavity of the shell. In the related art, the top cover and the shell 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 points of these two materials are above 1500°C. Another type of shell material is 3003 series aluminum or 7 series aluminum. The melting points of these two types of aluminum are 600°C to 800°C, and the melting point of the diaphragm in the pole piece assembly is basically within 120°C to 360°C. In the manufacturing process of the battery, the pole piece assembly is usually fixed in the inner cavity of the shell, and then the top cover is laser welded to close the open end of the shell. The high temperature of the laser used in the laser welding process of the shell and the top cover will corrode the low-melting-point diaphragm and insulating parts. When the high temperature of the laser corrodes the diaphragm, it will cause the diaphragm to shrink, and then cause the insulation failure between the positive and negative electrodes. Utility Model Content

[0003] The embodiments of the present utility model provide a battery and a battery pack, which can improve the technical problem of diaphragm shrinkage caused by high-energy laser used for welding the shell and the top cover.

[0004] In a first aspect, an embodiment of the present invention provides a battery, comprising:

[0005] a housing having an open end;

[0006] A top cover assembly, the top cover assembly comprising a cover plate, the cover plate being welded to the open end of the shell to cover the pole piece assembly;

[0007] a pole piece assembly, the pole piece assembly being accommodated in the inner cavity of the shell;

[0008] A gap is provided between the top end surface of the pole piece assembly and the open end of the shell, and the height of the gap is set to Gap A, 0.725 mm ≤ Gap A ≤ 3.94 mm.

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

[0010] In an embodiment, a thermal insulation layer is further included on the inner wall of the shell, the thermal insulation layer is arranged outside the welding fusion zone, a part of the thermal insulation layer is located between the pole piece assembly and the shell, and another part of the thermal insulation layer is located in the gap.

[0011] In an embodiment, the height of the thermal insulation layer extending along the height direction of the shell is L1, and 1.5 mm≤L1≤2.5 mm.

[0012] In an embodiment, the projected height of the thermal insulation layer on the pole piece assembly is d2, and the difference between L1 and d2 is not less than 0.5;

[0013] and / or, 1.0 mm≤d2≤2.0 mm.

[0014] In an embodiment, the thickness of the thermal insulation layer is t1, and 20 μm≤t1≤35 μm.

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

[0016] In an embodiment, the thermal conductivity of the material forming the thermal insulation layer is not greater than 0.064 W / (m·℃).

[0017] In an embodiment, the battery includes a first negative current collector and a positive current collector electrically connected with the top cover assembly, the pole piece assembly includes a positive pole piece and a negative pole piece, one end of the positive pole piece is connected with a positive lug, one end of the negative pole piece is connected with a negative lug, the positive lug is welded on the positive current collector, and a part of the negative lug is welded on the first negative current collector.

[0018] The top cover assembly includes a first insulating member, a part of the first insulating member is arranged between the cover plate and the positive current collector, another part of the first insulating member is used to support the first negative current collector, the first negative current collector, the first insulating member and the positive current collector are sequentially arranged along the radial direction of the shell from the outer side surface of the shell to the central axis direction of the shell, or the positive current collector, the first insulating member and the first negative current collector are sequentially arranged along the radial direction of the shell from the outer side surface of the shell to the central axis direction of the shell.

[0019] In an embodiment, the battery further includes a second negative current collector electrically connected at the bottom end of the shell, and another part of the negative lug is welded on the second negative current collector.

[0020] In one embodiment, the top cover assembly includes a positive electrode post and a liquid injection hole arranged on the positive electrode post, the positive electrode post is welded to the positive electrode busbar, and the top cover assembly also includes a sealing column for closing the liquid injection hole, and the sealing column is welded to the positive electrode post.

[0021] In a second aspect, an embodiment of the present invention provides a battery pack comprising a plurality of the above-mentioned batteries.

[0022] Beneficial effects of the embodiments of the present utility model:

[0023] In an embodiment of the present utility model, by controlling the gap Gap A between the top surface of the electrode assembly and the open end of the shell to be ≥0.725 mm, the high temperature used in the welding process of the shell and the cover plate can be prevented from causing the diaphragm in the electrode assembly to shrink. Furthermore, by controlling the gap Gap A between the electrode assembly and the open end of the shell to be ≤3.45 mm, the gap Gap A between the electrode assembly and the open end of the shell can be prevented from being too large, resulting in a low capacity utilization rate inside the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the 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 work.

[0025] Figure 1 Schematic diagram of the cross-sectional structure of a battery provided in an embodiment of the present utility model;

[0026] Figure 2 This is a schematic cross-sectional view of a battery with the top cover assembly removed, provided by an embodiment of the present invention;

[0027] Figure 3 yes Figure 2 A partial enlarged view of

[0028] Figure 4 yes Figure 3 A partial enlarged view of

[0029] Figure 5 This is a schematic cross-sectional view of the top cover assembly of a battery provided in a comparative example of the present utility model before use;

[0030] Figure 6 This is a schematic cross-sectional view of the top cover assembly of the battery provided in the comparative example of the present utility model after use;

[0031] Figure 7 yes Figure 1A partial enlarged view of

[0032] Figure 8 This is a schematic diagram of the top view of the battery provided in an embodiment of the present utility model;

[0033] Figure Number:

[0034] 100, battery; 110, housing; 111, opening end; 112, bottom end

[0035] 10. Top cover assembly; 11. Cover plate; 12. Positive electrode column; 13. First insulating member; 14. Sealing element; 15. Explosion-proof valve; 16. Liquid injection hole; 17. Sealing column; 18. Groove portion;

[0036] 20. Pole piece assembly; 210. Top surface of pole piece assembly; 21. Diaphragm; 22. Positive electrode piece; 221. Positive electrode tab; 23. Negative electrode piece; 231. Negative electrode tab;

[0037] 30. Second insulating member;

[0038] 41. Positive electrode current collecting plate; 42. First negative electrode current collecting plate; 43. Second negative electrode current collecting plate;

[0039] 50. Insulation layer; 51. Welding fusion zone;

[0040] 60. External positive electrode welding area; 61. External negative electrode welding area. DETAILED DESCRIPTION

[0041] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention. In addition, it should be understood that the specific implementation methods described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention. In the present invention, unless otherwise specified, the directional words used, such as "upper" and "lower", generally refer to the upper and lower parts of the device in actual use or working state, specifically the drawing direction in the accompanying drawings; while "inside" and "outside" refer to the outline of the device.

[0042] The embodiment of the present application provides a battery 100, which can be a cylindrical battery or a square battery. Figures 1 to 4As shown, the battery 100 includes a shell 110, a top cover assembly 10 and a pole piece assembly 20. The shell 110 is constructed as a hollow structure with one end open. The pole piece assembly 20 is accommodated in the inner cavity of the shell 110, and the top cover assembly 10 is connected to the open end of the shell 110.

[0043] like Figure 3 As shown, the electrode assembly 20 includes a positive electrode sheet 22, a negative electrode sheet 23, and a separator 21 for separating the positive electrode sheet 22 from the negative electrode sheet 23. In a cylindrical battery, the electrode assembly 20 can be configured to be wound along its central axis to form a core assembly structure. In a prismatic battery, the electrode assembly 20 can be configured to be stacked layer by layer along the height direction of the housing 110 to form a laminated assembly structure.

[0044] The top cap assembly 10 includes a cover plate 11, a pole, and an insulator. The pole is fixed to the cover plate 11, with one end of the pole extending through the cover plate 11. The top cap assembly 10 may include at least one of a positive pole 12 and a negative pole. The battery 100 is also provided with multiple current collecting trays, including a positive current collecting tray 41 and a negative current collecting tray. The end of the positive electrode sheet 22 is connected to a positive electrode tab 221, which is folded and connected to the positive current collecting tray 41. The end of the negative electrode sheet 23 is connected to a negative electrode tab 231, which is folded and connected to the negative current collecting tray. The cover plate 11 is welded to the open end of the housing 110 to cover the pole sheet assembly 20.

[0045] In one example, the top cover assembly 10 includes a positive electrode post 12, the positive current collecting disc 41 is further welded to the positive electrode post 12, and the negative current collecting disc is 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 electrode post, the negative current collecting disc is welded to the negative electrode post, and the positive current collecting disc is further welded to the bottom end 112 of the housing 110 or the cover plate 11. In other optional examples, the top cover assembly 10 includes a positive electrode post 12 and a negative electrode post, the positive current collecting disc 41 is welded to the positive electrode post 12, and the negative current collecting disc is welded to the negative electrode post.

[0046] In the related art, the cover plate 11 and the shell 110 are fully sealed by laser welding. The cover plate 11 and the shell 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 steel 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 in the shell 110 is usually made of a polymer material. , for example, a PP diaphragm 21 or a PE diaphragm 21, wherein the melting point of the single-layer PP diaphragm 21 is 160°C to 165°C, and the melting point of the single-layer PE diaphragm 21 is 130°C to 135°C. Therefore, during the laser welding process of the cover plate 11 and the shell 110, the high temperature generated by the laser will thermally corrode the diaphragm 21 in the electrode assembly 20 arranged near the cover plate 11, thereby causing the diaphragm 21 to shrink, thereby causing the positive electrode plate 22 and the negative electrode plate 23 at the shrinkage point of the diaphragm 21 to contact and short-circuit.

[0047] In response to the above problems, in the embodiments of the present application, the structure of the battery 100 is improved so that there is a suitable distance between the top surface 210 of the pole piece assembly 20 and the welding connection end of the shell 110 and the cover plate 11. During the laser welding process of the shell 110 and the cover plate 11, the high temperature generated by the laser is unlikely to cause thermal corrosion to the diaphragm 21 in the pole piece assembly 20, thereby avoiding shrinkage of the diaphragm 21.

[0048] refer to Figure 1 As shown, the distance between the top end of the pole piece assembly 20 and the open end 111 of the housing 110 is Gap A, and 0.725 mm ≤ Gap A ≤ 3.45 mm. The value of Gap A can be 0.8 mm, 1.0 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2.0 mm, 2.2 mm, 2.4 mm, 2.6 mm, 2.8 mm, 3.0 mm, 3.2 mm, 3.4 mm, or a value between any two of the above values ​​or a range between any two of the above values.

[0049] Further references Figure 5 and Figure 6As shown, the inventors have found through research that when the distance Gap A between the top of the pole piece assembly 20 and the open end 111 of the shell 110 is set to 0.46 mm, it is found through measurement that the contraction distance d0 of the diaphragm 21 in the pole piece assembly 20 is 0.23 mm. Therefore, under the premise that the energy of the laser used for laser welding between the cover plate 11 and the shell 110 remains unchanged, the distance Gap A between the top of the pole piece assembly 20 and the open end 111 of the shell 110 is set to be greater than 0.7 mm, so that the pole piece assembly 20 is located outside the laser high temperature zone during the laser welding process between the cover plate 11 and the shell 110, and thus the high temperature of the laser will not affect the pole piece assembly 20. Further, the inventors have found through research that when the distance Gap A between the top of the pole piece assembly 20 and the open end 111 of the shell 110 is set to be equal to 0.725 mm, the diaphragm 21 of the pole piece assembly 20 will not be affected by the high temperature during the laser welding process.

[0050] Considering that when the value of the gap Gap A between the top of the pole piece assembly 20 and the open end 111 of the shell 110 is too large, the internal space utilization of the battery 100 will be too low. The internal space utilization of the battery 100 can be defined as the space occupied by the pole piece assembly 20 inside the battery 100. The pole piece assembly 20 is the active material component of the battery 100. When the pole piece assembly 20 occupies a larger space, the capacity of the battery 100 of the same volume is greater. In a preferred embodiment, the gap Gap A between the top of the pole piece assembly 20 and the open end 111 of the shell 110 is set to no more than 3.45mm. Taking the 18450 battery as an example, when the gap Gap A is set to 4mm, the internal space utilization of the battery 100 is reduced by 2% relative to when the gap Gap A is set to 3mm.

[0051] It should be noted that the measurement method of the above-mentioned gap Gap A is that when the starting point of the welding point between the cover plate 11 and the shell 110 is the top of the shell 110, the gap Gap A is the gap extending downward from the open end 111 of the shell 110 to the top end surface 210 of the pole piece assembly 20; when the starting point of the welding point between the cover plate 11 and the shell 110 is a certain distance away from the top end surface of the shell 110, the gap Gap A is the gap extending downward from the starting point of the welding point between the shell 110 and the cover plate 11 to the top end surface 210 of the pole piece assembly 20, wherein the starting point of the welding point between the shell 110 and the cover plate 11 is the first weld mark formed between the shell 110 and the cover plate 11, wherein the first weld mark is set to be the weld mark closest to the top end surface of the shell 110.

[0052] Further references Figures 1 to 4As shown, a welded fusion zone 51 is formed between the housing 110 and the cover plate 11. The height of the welded fusion zone 51 along the height direction of the housing 110 is d1. The thickness of the housing 110 is t. The ratio of the height d1 of the welded fusion zone 51 to the thickness t of the housing 110 is 1.1 to 1.8 (inclusive), and the welded fusion zone 51 is located in the area corresponding to Gap A, that is, d1 < Gap A. Furthermore, the ratio of the height d1 of the welded 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 aforementioned values, or a range between any two of the aforementioned values.

[0053] The height direction of the housing 110 is as follows: Figure 1 In the Y direction shown, the housing 110 includes an open end 111 and a bottom end 112 oppositely disposed. The shortest distance between the open end 111 and the bottom end 112 is parallel to the height direction of the housing 110. The cover plate 11 is connected to the open end 111 of the housing 110. A terminal post is typically disposed on the cover plate 11 or the bottom end 112 of the housing 110. The terminal post can be a positive terminal post or a negative terminal post. In cylindrical batteries, the height direction of the housing 110 coincides with the longitudinal direction of the electrode assembly 20.

[0054] According to the physical properties of the materials of the shell 110 and the cover plate 11, laser welding is performed between the shell 110 and the cover plate 11. The energy used by the laser is configured to melt the weld between the shell 110 and the cover plate 11. The shell 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 shell 110 and the cover plate 11, the height d1 corresponding to the weld fusion zone 51 of the shell 110 in the thickness direction and the height direction during the welding process is not less than the corresponding thickness t. When the ratio between the height d1 of the weld fusion zone 51 and the thickness t of the shell 110 is less than 1.1, the height of the weld fusion zone 51 is insufficient, thereby resulting in insufficient bonding strength between the shell 110 and the top cover assembly 10. When the ratio between the height d1 of the weld fusion zone 51 and the thickness t of the shell 110 is greater than 1.8, the difference between Gap A and d1 is small, which is not conducive to protecting the diaphragm 21 in the electrode assembly 20.

[0055] The thickness of the shell 110 is defined as the wall thickness of the shell 110, and t is set to 0.25mm~0.8mm. In a specific implementation, t can be set to 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, and a value between any two of the above values, or a range between any two of the above values. When the thickness of the shell 110 is less than 0.25mm, the strength of the shell 110 will be insufficient, which will cause the shell 110 to be easily punctured or deformed, and the strength of the battery 100 will be insufficient. When the thickness of the shell 110 is greater than 0.8mm, the weight of the battery 100 will increase. When the volume of the battery 100 remains unchanged, the volume inside the battery 100 will be compressed, which is not conducive to the lightweight design of the battery 100.

[0056] Further references Figure 3 and Figure 4 As shown, a heat-insulating layer 50 is further provided on the inner wall of the housing 110. The heat-insulating layer 50 is staggered with the welding fusion zone 51 to prevent the provision of the heat-insulating layer 50 from affecting the welding between the housing 110 and the cover plate 11. A portion of the heat-insulating layer 50 is located between the pole piece assembly 20 and the housing 110, and another portion of the heat-insulating layer 50 is located within the aforementioned gap Gap A. The heat-insulating layer 50 is used to further prevent heat from being transferred from the welding fusion zone 51 to the outer diaphragm 21 of the pole piece assembly 20, thereby causing the outer diaphragm 21 of the pole piece assembly 20 to be thermally corroded and shrunk.

[0057] In a preferred embodiment, the height L1 of the thermal insulation layer 50 extending along the height direction of the housing 110 is 1.5 mm ≤ L1 ≤ 2.5 mm. In a specific embodiment, the height L1 of the thermal insulation layer 50 can be 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2.0 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, or a value between any two of the above values, or a range between any two of the above values.

[0058] Further references Figure 3 and Figure 4As shown, the height of the separator 21 in the winding core assembly is greater than the height of the negative electrode sheet 23, which is greater than the height of the positive electrode sheet 22. The insulation layer 50 is configured to cover the portion of the separator 21 that extends beyond the negative electrode sheet 23. The height of the separator 21 beyond the negative electrode sheet 23 is typically set to 1.2 mm to 1.75 mm, and thus the height L1 of the insulation layer 50 is set to 1.5 mm to 2.5 mm. When the height L1 of the insulation layer 50 is less than 1.5 mm, the insulation layer 50 cannot provide effective thermal insulation protection for the separator 21. When the height L1 of the insulation layer 50 is set to greater than 2.5 mm, the insulation layer 50 will extend to the weld fusion zone 51 between the housing 110 and the cover plate 11, thereby affecting the weld between the housing 110 and the cover plate 11.

[0059] The thermal insulation layer 50 is preferably made of a low thermal conductivity, corrosion-resistant elastic material, and the thermal conductivity of the material forming the thermal insulation layer 50 is not greater than 0.064W / (m·℃). Suitable materials include EPDM rubber with added nanoporous silicon material, wherein the nanoporous silicon material is used as a filler with low thermal conductivity to reduce the thermal conductivity of the thermal insulation layer 50. EPDM rubber has excellent corrosion resistance and reinforcement properties.

[0060] The projected height of the thermal insulation layer 50 on the pole piece assembly 20 is d2, and the difference between L1 and d2 is not less than 0.5, and / or 1.0 mm ≤ d2 ≤ 2.0 mm. The difference between L1 and d2 is the distance that the top of the thermal insulation layer 50 exceeds the top of the pole piece assembly 20. Therefore, in a specific implementation, the projected height d2 of the thermal insulation layer 50 on the pole piece assembly 20 can be 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, or a value between any two of the above values ​​or a range between any two of the above values. The projected height d2 of the insulation layer 50 on the pole piece assembly 20 is the height d2 of the insulation layer 50 applied to the inner side of the pole piece assembly 20. Therefore, when the projected height d2 of the insulation layer 50 on the pole piece assembly 20 is less than 1.0 mm, a portion of the outer diaphragm 21 of the pole piece assembly 20 is still within the thermal radiation range of the housing 110 near the weld fusion zone 51. The inner side of this portion of the outer diaphragm 21 is not provided with the insulation layer 50 for insulation, which can cause this portion of the diaphragm 21 to be easily corroded and shrink. When the projected height d2 of the insulation layer 50 on the pole piece assembly 20 is greater than 2.0 mm, the insulation layer 50 material is overused, which is not conducive to saving the cost of the battery 100.

[0061] In a preferred embodiment, the thickness t1 of the thermal insulation layer 50 is greater than 20 μm, and the thickness t1 of the thermal insulation layer 50 is less than 100 μm. Furthermore, the thickness t1 of the thermal insulation layer 50 is 20 μm to 35 μm (including the endpoint values). In a specific embodiment, the thickness t1 of the thermal insulation layer 50 can be 22 μm, 24 μm, 26 μm, 28 μm, 30 μm, 32 μm, 34 μm, or a value between any two of the above values, or a range between any two of the above values. When the thickness t1 of the thermal insulation layer 50 is less than 20 μm, the thermal insulation capacity of the thermal insulation layer 50 will be insufficient, and a portion of the diaphragm 21 will still be 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 20um, pores are easily formed inside the insulation layer 50, and the heat in the welding fusion zone 51 will further diffuse through the pores to the diaphragm 21 of the core assembly, thereby causing the diaphragm 21 to shrink. When the thickness t1 of the insulation layer 50 is greater than 35μm, the insulation layer 50 will occupy more internal space of the shell 110, resulting in a reduction in the utilization rate of the internal space of the shell 110.

[0062] Through research, the inventors discovered that Gap A = L1 - d2 + d1 + 1 mm. When Gap A satisfies the aforementioned relationship with L1, d2, and d1, the diaphragm 21 in the electrode assembly 20 within the battery 100 will not be corroded by the high-power laser used during the welding process between the housing 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 primarily related to the width tolerance of the thermal insulation layer 50. Thermal insulation layer 50 is formed by machining the inner cylindrical wall of the cylindrical battery 100 and is configured as a UV liquid coating. Therefore, its tolerance range is relatively large, at ±0.5 mm, and the tolerance bandwidth of thermal insulation layer 50 is 1 mm.

[0063] The specific values ​​of Gap A, the thickness t of the housing 110, the height d1 of the welding fusion zone 51, the height L1 of the thermal insulation layer 50, and the projected height d2 of the thermal insulation layer 50 on the pole piece assembly 20 can be referred to the eight specific embodiments provided in Table 1 below:

[0064] Table 1 Parameters of the welding fusion zone 51 and the insulation layer 50 of the shell 110 and the cover plate 11

[0065] 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

[0066] By analyzing the data in Table 1, the ratio of the height d1 of the welding fusion zone 51 to 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 projected height d2 of the insulation layer 50 on the pole piece 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.

[0067] By testing and analyzing the batteries 100 of the various embodiments in Table 1, when the settings of the welding fusion zone 51 and the insulation layer 50 between the shell 110 and the top cover assembly 10 in the battery 100 meet the requirements of the above Table 1, the diaphragm 21 in the pole piece assembly 20 will not be affected by the high-energy laser used in the laser welding process of the shell 110 and the top cover assembly 10.

[0068] The top cover assembly 10 usually includes a cover plate 11, a pole and a plastic insulating part. A part of the plastic insulating part is arranged between the cover plate 11 and the pole. In the related art, the plastic insulating part arranged near the pole is usually close to the welding fusion zone 51 between the shell 110 and the cover plate 11. The melting point of the insulating part is usually 120℃~360℃. Therefore, the high-energy laser used in the welding fusion zone 51 will further corrode the insulating part near the pole. The insulating part will melt to form evaporated material, which will further remain in the welding gap, resulting in holes in the welding area, and then forming a leakage channel.

[0069] In response to the above problems, the structure of the top cover assembly 10 and the assembly process of the battery 100 are further optimized in the embodiments of the present application, thereby preventing the insulating parts from being corroded by the high-energy laser used for welding, thereby preventing the formation of a leakage channel on the top cover assembly 10.

[0070] Further references Figure 1 and Figure 8 As shown, a positive electrode column 12 is provided on the top cover assembly 10, and the electrode sheet assembly 20 includes a positive electrode sheet 22 and a negative electrode sheet 23 arranged at intervals. One end of the positive electrode sheet 22 is connected to a positive electrode tab 221, and one end of the negative electrode sheet 23 is connected to a negative electrode tab 231. The positive electrode tab 221 is folded and welded to the positive current collecting disk 41, and the positive current collecting disk 41 is welded to the positive electrode column 12. The negative electrode tab 231 is folded and welded to the negative current collecting disk, and the negative current collecting disk is welded to the bottom end 112 of the shell 110 or the cover plate 11.

[0071] In a preferred embodiment, both the positive and negative output terminals of the battery 100 are disposed 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 tab 231 is welded to the first negative current collector 42, while another portion of the negative electrode tab 231 is welded to the second negative current collector 43. A recess 18 is provided on the cover plate 11, the bottom end surface of which is welded to the first negative current collector 42. By configuring the negative current collector in two parts, the spacing between the first negative current collector 42 and the weld fusion zone 51 can be further increased, thereby preventing high-temperature corrosion of the first insulating member 13 near the first negative current collector 42 caused by high-energy laser light within the weld fusion zone 51.

[0072] Further references Figure 1 and Figure 8 As shown, the top cover assembly 10 includes a positive electrode column 12 , which is arranged on the central axis of the battery 100 , a positive current collecting disc 41 welded to the positive electrode column 12 , and a first negative current collecting disc 42 welded to the cover plate 11 .

[0073] The top cover assembly 10 includes a first insulating member 13, which is made of a plastic material. A portion of the first insulating member 13 is disposed between the cover plate 11 and the positive current collector plate 41, while another portion of the first insulating member 13 supports the first negative current collector plate 42. The first negative current collector plate 42, the first insulating member 13, and the positive current collector plate 41 are sequentially disposed along the radial direction of the housing 110, from the outer side surface of the housing 110 toward the central axis of the housing 110. Because the first insulating member 13 is disposed away from the weld fusion zone 51 between the housing 110 and the cover plate 11, the high-energy laser used during the welding process of the housing 110 and the cover plate 11 does 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 space is provided between the first negative current collector plate 42 and the inner wall of the housing 110 to provide further thermal insulation.

[0074] A second insulating member 30 is further provided at the bottom end 112 of the housing 110 . The second insulating member 30 is made of plastic material and is used to further support and fix the second negative electrode current collecting disc 43 .

[0075] In other optional examples, the top cover assembly 10 includes a negative electrode post, which is arranged on the central axis of the battery 100, the negative current collecting disc is welded to the negative electrode post, the positive current collecting disc 41 is welded to the cover plate 11, a portion of the first insulating member 13 is arranged between the cover plate 11 and the negative current collecting disc, and another portion of the first insulating member 13 is used to support the positive current collecting disc 41. The positive current collecting disc 41, the first insulating member 13 and the first negative current collecting disc are arranged in sequence along the radial direction of the shell 110 from the outer side surface of the shell 110 to the central axis of the shell 110.

[0076] In the above-mentioned battery 100 structure, the first insulating member 13 and the second insulating member 30 are both arranged away from the welding fusion zone 51 between the shell 110 and the cover plate 11. Specifically, the shell 110, the insulating layer 50, the negative electrode collecting plate and the first insulating member 13 are arranged in sequence along the radial direction of the shell 110 toward the central axis of the shell 110. Therefore, the high temperature generated in the welding fusion zone 51 between the shell 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 zone 51 from being transferred to the first insulating member 13.

[0077] 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 the connecting piece or the connecting circuit to the negative electrode post or the cover plate 11 of the battery 100, and the external positive electrode welding area 60 is used for connecting the connecting piece or the connecting circuit to the positive electrode post 12 or the cover plate 11 of the battery 100. Figure 7 As shown, the external positive electrode welding region 60 is located in the central area of ​​the battery 100 , and the external negative electrode welding region 61 is located on the periphery of the external positive electrode welding region 60 .

[0078] 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 inside 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.

[0079] 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 scoreline set on the cover plate 11. The wall where the scoreline is located will be destroyed when subjected to pressure inside the battery 100, thereby forming a pressure relief port in a part of the cover plate 11.

[0080] The positive electrode column 12 is provided with an injection hole 16 and a sealing column 17 for sealing the injection hole 16. The sealing column 17 is laser welded to the injection hole 16 of the positive electrode column 12. A through hole is further provided on the positive electrode current collecting plate 41, and the through hole is arranged directly opposite the injection hole 16 on the positive electrode column 12.

[0081] The present application provides a method for manufacturing the battery 100, which includes:

[0082] In the first step, a thermal insulation layer 50 is applied to the inner wall of the housing 110 and dried. The thermal insulation layer 50 is applied in accordance with the requirements of the aforementioned embodiment. Specifically, the thermal insulation layer 50 is offset from the weld fusion zone 51, with a portion of the thermal insulation layer 50 positioned between the pole piece assembly 20 and the housing 110, and another portion of the thermal insulation layer 50 positioned within the aforementioned gap Gap A. Suitable materials for forming the thermal insulation layer 50 include EPDM rubber with nanoporous silicon material added thereto. The thermal insulation layer, prepared by using EPDM as a base material and nanoporous silicon material as a filler, can be directly applied to the inner wall of the housing by spraying, brushing, or centrifugation, and then heated and cured to form the thermal insulation layer.

[0083] In the second step, the positive electrode tab 221 of the electrode assembly 20 is folded and welded to the positive electrode current collecting plate 41, and the negative electrode tab 231 of the electrode assembly 20 is folded and welded to the negative electrode current collecting plate; wherein the positive electrode tab 221 is configured to be folded in the direction close to the top cover assembly 10, and the positive electrode tab 221 and the positive electrode current collecting plate 41 can be welded by resistance welding or laser welding. A part of the negative electrode tab 231 is folded in the direction close to the top cover assembly 10, and the negative electrode tab 231 of this part is welded to the first negative electrode current collecting plate 42, and another part of the negative electrode tab 231 is folded in the direction close to the bottom end 112 of the shell 110, and the negative electrode tab 231 of this part is welded to the second negative electrode current collecting plate 43.

[0084] The third step is to place the electrode assembly 20 into the inner cavity of the shell 110 with the output end facing upward; the output end of the electrode assembly 20 includes a positive electrode tab 221 and a negative electrode tab 231. In the above embodiment, the top cover assembly 10 is provided with a positive electrode column 12, so the end of the electrode assembly 20 with the positive electrode tab 221 is provided corresponding to the top open end of the shell 110.

[0085] The fourth step is to weld the positive current collecting disc 41 to the positive electrode post 12, and weld the negative current collecting disc to the shell 110 and / or the cover plate 11; wherein, the welding method of the positive current collecting disc 41 to the positive electrode post 12 is preferably laser welding. In the above embodiment, the negative current collecting disc includes a first negative current collecting disc 42 and a second negative current collecting disc 43, the first negative current collecting disc 42 is welded to the cover plate 11, and the second negative current collecting disc 43 is welded to the bottom end of the shell 110.

[0086] In the fifth step, the electrolyte is injected into the interior of the battery 100 through the injection hole 16 for formation; the electrolyte is injected through the injection hole 16 set on the positive electrode column 12 using an injection tool, and the electrolyte further enters the electrode assembly 20 through the through hole set on the positive current collecting plate 41.

[0087] Step 6: The liquid injection hole 16 of the top cover assembly 10 is sealed by welding using a sealing column 17; the sealing column 17 and the positive electrode column 12 on the top cover assembly 10 are preferably welded by laser welding;

[0088] The seventh step is to package the battery 100. The specific packaging method is selected according to the type of battery 100 to be formed. For example, cylindrical batteries and square batteries are often packaged in hard shells, while soft-pack batteries are often packaged in aluminum-plastic films.

[0089] Because the thermal insulation layer 50 is coated on the inner wall of the battery 100 housing 110, the diaphragm 21 located inside the thermal insulation layer 50 is effectively protected from corrosion by the high temperature energy generated by the weld fusion zone 51. Furthermore, after welding the housing 110 to the cover plate 11, the 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.

[0090] The present invention also provides a battery pack, which includes a box and a plurality of batteries arranged inside the box. The plurality of batteries are arranged to be connected in series, in parallel or in mixed connection to meet the capacity requirements of the battery pack. The battery pack is used to power electric vehicles or electric tools.

[0091] The above is a detailed introduction to the embodiments of the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, based on the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the contents of this specification should not be understood as limiting the present invention.

Claims

1. A battery, characterized in that: include: a housing having an open end; a pole piece assembly, the pole piece assembly being accommodated in the inner cavity of the shell; A top cover assembly, the top cover assembly comprising a cover plate, the cover plate being welded to the open end of the shell to cover the pole piece assembly; A gap is provided between the top end surface of the pole piece assembly and the open end of the shell, and the height of the gap is set to Gap A, 0.725 mm ≤ Gap A ≤ 3.94 mm.

2. The battery according to claim 1, characterized in that The shell is provided with a welding fusion zone, which is used for welding the shell and the cover plate. The height of the welding fusion zone extending 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 an insulation layer arranged on the inner wall of the shell, the insulation layer is arranged outside the welding fusion zone, a part of the insulation layer is located between the pole piece assembly and the shell, and another part of the insulation layer is located in the gap.

4. The battery according to claim 3, characterized in that The height of the heat insulating layer extending along the height direction of the shell is L1, and 1.5 mm≤L1≤2.5 mm.

5. The battery according to claim 4, characterized in that The projected height of the thermal insulation layer on the pole piece 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 thermal insulation layer is t1, 20 μm≤t1≤35 μm.

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

8. The battery according to claim 3, characterized in that The thermal conductivity of the material used to form the thermal insulation layer is no greater than 0.064 W / (m·°C).

9. The battery according to any one of claims 1 to 8, characterized in that: The battery includes a first negative electrode current collecting plate and a positive electrode current collecting plate electrically connected to the top cover assembly, the electrode plate assembly includes a positive electrode plate and a negative electrode plate, one end of the positive electrode plate is connected to a positive electrode tab, one end of the negative electrode plate is connected to a negative electrode tab, the positive electrode tab is welded to the positive electrode current collecting plate, and a portion of the negative electrode tab is welded to the first negative electrode current collecting plate; The top cover assembly includes a first insulating member, a portion of which is arranged between the cover plate and the positive current collecting disc, and the other portion of the first insulating member is used to support the first negative current collecting disc, and the first negative current collecting disc, the first insulating member and the positive current collecting disc are arranged in sequence along the radial direction of the shell from the outer side surface of the shell to the central axis of the shell, or the positive current collecting disc, the first insulating member and the first negative current collecting disc are arranged in sequence along the radial direction of the shell from the outer side surface of the shell to the central axis of the shell.

10. The battery according to claim 9, characterized in that The battery further includes a second negative electrode current collecting disk electrically connected to the bottom end of the shell, and another portion of the negative electrode tab is welded to the second negative electrode current collecting disk.

11. The battery according to claim 9, characterized in that The top cover assembly includes a positive electrode column, which is provided with a liquid injection hole and is welded to the positive current collecting plate. The top cover assembly also includes a sealing column for closing the liquid injection hole, which is welded to the positive electrode column.

12. A battery pack, characterized in that: The battery pack comprises a plurality of batteries according to any one of claims 1 to 11.

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