Cylindrical battery, battery pack and electronic device

Abstract

The utility model provides a cylindrical battery, a battery pack and an electronic device. The cylindrical battery includes: a case; the electrode assembly is accommodated in the shell and comprises a winding structure formed by laminating and winding a positive plate, a diaphragm and a negative plate; a negative current collector of the negative plate comprises a negative active material coating region and a negative active material non-coating region; the negative electrode non-coated active material region comprises a negative electrode flat part and a negative electrode transition part; the negative electrode transition part comprises a first negative electrode bending part and a preset area which are connected along a direction opposite to the preset direction; wherein the preset area comprises a second negative electrode bending part, and the preset area is partially covered with a reinforcing layer. The second negative electrode bending part is arranged in the preset area, so that the preset area expands outwards in the radial direction of the winding structure, and the safety of the battery cell is improved; the preset area is partially covered with the reinforcing layer, so that the bending supporting performance of the area, not coated with the active substance, of the negative electrode can be improved, and the safety of the battery cell is further improved.

Description

Technical Field

[0001] This utility model relates to the field of batteries, and in particular to a cylindrical battery, a battery pack, and an electronic device. Background Technology

[0002] In recent years, with the rapid development of electric vehicles, consumer electronics, and new energy storage systems, battery technology has become an important factor in the development of electric vehicles.

[0003] In the development of battery technology, how to improve the safety of battery cells is a technical problem that urgently needs to be solved. Utility Model Content

[0004] The technical problem to be solved by this utility model is to overcome the above-mentioned technical problems of the prior art and provide a cylindrical battery, battery pack and electronic device.

[0005] The present invention solves the above-mentioned technical problems through the following technical solution:

[0006] A cylindrical battery, characterized in that it comprises:

[0007] case;

[0008] An electrode assembly is housed within the housing. The electrode assembly includes a positive electrode sheet, a separator, and a negative electrode sheet stacked and wound together to form a wound structure. The positive electrode sheet includes a positive current collector, and the negative electrode sheet includes a negative current collector. Along the height direction of the wound structure, the negative current collector includes a negative electrode coated active material region covered by a negative electrode active material layer and a negative electrode uncoated active material region not covered by the negative electrode active material layer.

[0009] The uncoated active material region of the negative electrode includes a negative electrode flat portion away from the negative electrode coated active material region, and a negative electrode transition portion connecting the negative electrode flat portion and the negative electrode coated active material region. The negative electrode flat portion extends radially along the winding structure. The direction from the negative electrode coated active material region to the uncoated active material region of the negative electrode is a preset direction. The negative electrode transition portion includes a first negative electrode bend portion and a preset region connected in a direction opposite to the preset direction.

[0010] The preset area includes a second negative electrode bending portion, and the preset area is partially covered with a reinforcing layer.

[0011] In this technical solution, a first negative electrode bending section is provided to achieve bending of the uncoated active material area of ​​the negative electrode towards the central hole of the winding structure. A second negative electrode bending section is provided in a preset area to expand the preset area radially outward along the winding structure, thereby preventing the uncoated active material area of ​​the negative electrode from leaking into the positive current collector, thus improving the safety of the battery cell. Furthermore, by providing a reinforcing layer covering a portion of the preset area, the support of the bending of the uncoated active material area of ​​the negative electrode can be improved. Specifically, since the uncoated active material area of ​​the negative electrode starts to bend at the first negative electrode bending section, by covering a portion of the preset area with a reinforcing layer, the bending position in the height direction can be increased, thereby increasing the relative height position of the welding area of ​​the uncoated active material area of ​​the negative electrode and the separator, achieving the purpose of avoiding burns to the separator during welding, and further improving the safety of the battery cell.

[0012] Preferably, along the radial direction of the winding structure, the preset region includes a first negative electrode side away from the central hole of the winding structure and a second negative electrode side towards the central hole, wherein at least a portion of the first negative electrode side and / or the second negative electrode side is covered by the reinforcing layer.

[0013] Preferably, the reinforcing layer covers the second negative electrode bend; or,

[0014] The reinforcing layer does not cover the second negative electrode bending portion and is located between the negative electrode coated active material area and the second negative electrode bending portion.

[0015] Preferably, the number of the second negative electrode bends is one, the bending direction of the second negative electrode bend is different from that of the first negative electrode bend, and they are arranged opposite to each other along the radial direction; or,

[0016] There are multiple second negative electrode bending portions, which are arranged sequentially along the preset direction. The bending directions of adjacent second negative electrode bending portions are different. The second negative electrode bending portion closest to the first negative electrode bending portion has a different bending direction from the first negative electrode bending portion and is arranged opposite to it along the radial direction.

[0017] Preferably, the width of the uncoated active material area of ​​the negative electrode along the preset direction is W1, in mm;

[0018] Along the predetermined direction, the negative electrode active material layer and the reinforcing layer have a non-zero predetermined spacing G, in mm, satisfying 22 ≤ W1 / G ≤ 400; and / or,

[0019] Along the preset direction, the width of the negative electrode active material layer is W2, in mm, which satisfies 3≤W2 / W1≤11.

[0020] Preferably, the preset spacing G is 0.1mm-1.1mm.

[0021] Preferably, the ratio of the thickness of the reinforcing layer to the thickness of the current collector is 1-6, or the thickness of the negative electrode current collector is 4μm-5.5μm;

[0022] And / or,

[0023] The grayscale value of the reinforcing layer is 0-110;

[0024] And / or,

[0025] At least a portion of the negative electrode uncoated active material area forms a negative electrode tab, and each negative electrode tab located on the outermost ring is provided with a first negative electrode bending portion and a second negative electrode bending portion.

[0026] Preferably, the housing includes surrounding sidewalls, one end of which is formed with an opening;

[0027] The cylindrical battery also includes:

[0028] Cover plate, installed in the opening;

[0029] A negative electrode current collector is disposed between the electrode assembly and the cover plate and is electrically connected to the housing. One side of the connecting piece of the negative electrode current collector is welded to the flat part of the negative electrode.

[0030] The housing further includes a crimping portion, which is formed on one end of the side wall near the opening and recessed into the housing; the other side of the connecting piece of the negative electrode current collector is welded to the crimping portion.

[0031] or,

[0032] The outer periphery of the cover plate, the end of the side wall of the housing near the opening, and the outer periphery of the connecting piece of the negative electrode current collector are connected by welding.

[0033] A battery pack characterized in that it includes cylindrical batteries as described above.

[0034] An electronic device characterized in that it includes a battery pack as described above.

[0035] The positive and progressive effects of this utility model are as follows:

[0036] This invention achieves bending of the uncoated active material area of ​​the negative electrode towards the central hole of the winding structure by setting a first negative electrode bending portion; by setting a second negative electrode bending portion in a preset area, the preset area expands radially outward along the winding structure, thereby preventing the uncoated active material area of ​​the negative electrode from leaking into the positive current collector, thus improving the safety of the battery cell; furthermore, by covering the preset area with a reinforcing layer, the support of the bending of the uncoated active material area of ​​the negative electrode can be improved. Specifically, since the uncoated active material area of ​​the negative electrode starts to bend at the first negative electrode bending portion, by covering a portion of the preset area with a reinforcing layer, the bending position in the height direction can be improved, thereby increasing the relative height position of the welding area of ​​the uncoated active material area of ​​the negative electrode and the separator, achieving the purpose of avoiding burns to the separator during welding, further improving the safety of the battery cell. Attached Figure Description

[0037] Figure 1 This is a cross-sectional view of the cylindrical battery according to Embodiment 1 of this utility model.

[0038] Figure 2 for Figure 1 A magnified schematic diagram of part A in the middle.

[0039] Figure 3 This is a three-dimensional structural diagram of the electrode assembly of the cylindrical battery according to Embodiment 1 of this utility model.

[0040] Figure 4 This is a partial cross-sectional view of one embodiment of the electrode assembly of the cylindrical battery according to Embodiment 1 of this utility model.

[0041] Figure 5 for Figure 4 A magnified schematic diagram of part B in the middle section.

[0042] Figure 6 This is a partial cross-sectional view of the single-turn negative electrode sheet of the cylindrical battery according to Embodiment 1 of this utility model.

[0043] Figure 7 for Figure 6 A magnified schematic diagram of part C in the middle.

[0044] Figure 8 This is a schematic diagram of the structure of the negative electrode sheet of the cylindrical battery in Embodiment 1 of this utility model when it is not wound.

[0045] Figure 9 This is a partial cross-sectional view of the single-turn positive electrode sheet of the cylindrical battery according to Embodiment 1 of this utility model.

[0046] Figure 10 This is a partial cross-sectional view of another embodiment of the electrode assembly of the cylindrical battery according to Embodiment 1 of this utility model.

[0047] Figure 11 for Figure 10 A magnified schematic diagram of part D in the middle section.

[0048] Figure 12 This is a partial cross-sectional view of another embodiment of the electrode assembly of the cylindrical battery according to Embodiment 1 of this utility model.

[0049] Figure 13 for Figure 12 A magnified schematic diagram of part E in the middle section.

[0050] Figure 14 This is a partial cross-sectional view of another embodiment of the electrode assembly of the cylindrical battery according to Embodiment 1 of this utility model.

[0051] Figure 15 for Figure 14 A magnified schematic diagram of part F in the middle section.

[0052] Figure 16 This is a schematic diagram of the battery pack structure of Embodiment 1 of this utility model.

[0053] Figure 17 This is a schematic diagram of the electronic device according to Embodiment 1 of this utility model.

[0054] Figure 18 This is a partial cross-sectional view of the single-turn negative electrode sheet of the cylindrical battery according to Embodiment 2 of this utility model.

[0055] Figure 19 This is a cross-sectional view of the cylindrical battery of Embodiment 3 of this utility model.

[0056] Figure 20 for Figure 19 A magnified schematic diagram of part I in the middle section.

[0057] Explanation of reference numerals in the attached figures

[0058] Electronic device 1000; battery pack 100; housing 110; housing cover 120; working part 300; cylindrical battery 1; casing 10; end wall 11; side wall 12; receiving cavity 13; opening 14; electrode assembly 20; winding structure 201; central hole 2011; positive electrode plate 21; positive electrode current collector 211; positive electrode active material layer 2111; positive electrode coated active material area 212; positive electrode uncoated active material area 213; positive electrode flat part 214; positive electrode transition part 215; positive electrode bending part 216; positive electrode tab 217; positive electrode upright part 218; separator 22; Negative electrode sheet 23; negative electrode current collector 231; negative electrode active material layer 2311; negative electrode coated active material area 232; negative electrode uncoated active material area 233; negative electrode flat portion 234; negative electrode transition portion 235; first negative electrode bending portion 2361; preset area 2362; first negative electrode side 2361; second negative electrode side 2362; second negative electrode bending portion 2363; negative electrode tab 237; support layer 24; crimping portion 30; cover plate 40; insulating seal 50; positive electrode current collector 61; negative electrode current collector 62; connecting piece 621; electrode post 70; insulating component 80. Detailed Implementation

[0059] The present invention will be described more clearly and completely below with reference to the accompanying drawings, using a preferred embodiment.

[0060] Example 1

[0061] like Figure 1 and Figure 2 As shown, this embodiment provides a cylindrical battery 1. The cylindrical battery 1 includes a housing 10 and an electrode assembly 20, the electrode assembly 20 being housed within the housing 10.

[0062] like Figures 3 to 9 As shown, the electrode assembly 20 includes a spiral structure 201 formed by stacking and winding a positive electrode 21, a separator 22, and a negative electrode 23; the positive electrode 21 includes a positive current collector 211, and the negative electrode 23 includes a negative current collector 231; along the height direction H of the spiral structure 201, the negative current collector 231 includes a negative electrode coated active material region 232 covered by the negative electrode active material layer 2311 and a negative electrode uncoated active material region 233 not covered by the negative electrode active material layer 2311.

[0063] The uncoated active material region 233 includes a negative electrode flat portion 234 away from the negative electrode coated active material region 232, and a negative electrode transition portion 235 connecting the negative electrode flat portion 234 and the negative electrode coated active material region 232. The negative electrode flat portion 234 extends radially R along the winding structure 201. The direction from the negative electrode coated active material region 232 to the uncoated active material region 233 is a preset direction Q. The negative electrode transition portion 235 includes a first negative electrode bend portion 2361 and a preset region 2362 connected in a direction opposite to the preset direction Q.

[0064] The preset area 2362 includes a second negative electrode bending portion 2363, and the preset area 2362 is partially covered by a reinforcing layer 24.

[0065] Thus, by setting the first negative electrode bending portion 2361, the uncoated active material region 233 of the negative electrode is bent towards the central hole 2011 of the winding structure 201; by setting the second negative electrode bending portion 2363 in the preset region 2362, the preset region 2362 expands outward along the radial R of the winding structure 201, thereby preventing the uncoated active material region 233 of the negative electrode from contacting the leaking portion of the positive electrode current collector 211, thereby improving the safety of the battery cell; furthermore, by setting the preset region 2362 partially covered with a... The reinforcing layer 24 can improve the support of the uncoated active material region 233 of the negative electrode when bent. Specifically, since the uncoated active material region 233 of the negative electrode starts to bend at the first negative electrode bending part 2361, by covering a part of the preset area 2362 with the reinforcing layer 24, the position of the bend in the height direction H can be improved, thereby increasing the relative position of the welding area of ​​the uncoated active material region 233 of the negative electrode and the separator 22 in the height direction H, so as to avoid burning the separator 22 during welding and further improve the safety of the battery cell.

[0066] It should be noted that the extension of the negative electrode flat portion 234 along the radial direction R of the winding structure 201 means that the negative electrode flat portion 234 extends along the radial direction R of the winding structure 201 and in a direction close to the radial direction R of the winding structure 201. Since the preset region 2362 is located between the first negative electrode bending portion 2361 and the negative electrode coated active material region 232, that is, the preset region 2362 is the region of the negative electrode transition portion 235 near the edge of the negative electrode coated active material region 232 to the first negative electrode bending portion 2361.

[0067] The number of second negative electrode bending portions 2363 can be one or more. When there is only one second negative electrode bending portion 2363, the bending direction of the second negative electrode bending portion 2363 is different from that of the first negative electrode bending portion 2361, and they are arranged opposite each other along the radial direction R. In this way, by setting the bending direction of the second negative electrode bending portion 2363 to be different from that of the first negative electrode bending portion 2361, and arranging them opposite each other along the radial direction, the preset area 2362 can be better expanded outward along the radial direction R of the winding structure 201.

[0068] When there are multiple second negative electrode bending portions 2363, these portions are sequentially arranged along a preset direction Q, with adjacent second negative electrode bending portions 2363 having different bending directions. The second negative electrode bending portion 2363 closest to the first negative electrode bending portion 2361 has a different bending direction than the first negative electrode bending portion 2361 and is arranged opposite to it radially R. This arrangement, with the second negative electrode bending portion 2363 closest to the first negative electrode bending portion 2361 having a different bending direction and being arranged opposite to it radially R, better enables the preset area 2362 to expand outward along the radial direction R of the winding structure 201.

[0069] Preferably, along the radial direction R of the winding structure 201, the preset region 2362 includes a first negative electrode side 23621 facing away from the central hole 2011 of the winding structure 201 and a second negative electrode side 23622 facing the central hole 2011, wherein at least a portion of the first negative electrode side 23621 and / or the second negative electrode side 23622 is covered with a reinforcing layer 24. Thus, by covering at least a portion of the first negative electrode side 23621 and / or the second negative electrode side 23622 with the reinforcing layer 24, the bending position in the height direction H can be improved, thereby increasing the relative position of the welding area of ​​the uncoated active material region 233 of the negative electrode and the separator 22 in the height direction H, achieving the purpose of avoiding burns to the separator 22 during welding and improving the safety of the battery cell.

[0070] Please refer to the following: Figure 7 In this embodiment, both the first negative electrode side 23621 and the second negative electrode side 23622 are at least partially covered by the reinforcing layer 24. However, this is not a limitation. In other embodiments, only at least a portion of the first negative electrode side 23621 or only at least a portion of the second negative electrode side 23622 may be covered by the reinforcing layer 24, which can be adjusted according to design requirements.

[0071] The reinforcing layer 24 covers the second negative electrode bend 2363; or, the reinforcing layer 24 does not cover the second negative electrode bend 2363 and is located between the negative electrode coated active material region 232 and the second negative electrode bend 2363.

[0072] Specifically, in one embodiment of this example, please refer to [link / reference]. Figures 4 to 7 The number of second negative electrode bending portions 2363 is one, and the reinforcing layer 24 covers the second negative electrode bending portion 2363.

[0073] However, this is not the only embodiment; another implementation, such as Figure 10 and Figure 11 The number of second negative electrode bending portions 2363 is one, the reinforcing layer 24 does not cover the second negative electrode bending portion 2363, and is located between the negative electrode coated active material region 232 and the second negative electrode bending portion 2363.

[0074] However, this is not the only embodiment. In other embodiments, there are multiple second negative electrode bending portions 2363, which are sequentially arranged along a preset direction Q, and adjacent second negative electrode bending portions 2363 have different bending directions. Thus, the multiple second negative electrode bending portions 2363 with different bending directions cause the preset area 2362 to expand outward along the radial direction R of the winding structure 201, thereby preventing the uncoated active material area 233 of the negative electrode from contacting the leaking portion of the positive electrode current collector 211, thereby improving the safety of the battery cell. Furthermore, combined with the reinforcing layer 24, the support of the bending of the uncoated active material area 233 of the negative electrode can be improved, increasing the relative position of the welding area of ​​the uncoated active material area 233 and the separator 22 in the height direction H, achieving a certain heat insulation effect, and achieving the purpose of avoiding burns to the separator 22 during welding, further improving the safety of the battery cell. Here, "multiple" refers to two or more.

[0075] Specifically, in another embodiment of this example, as Figures 12 to 13 The number of second negative electrode bending portions 2363 is two, and the reinforcing layer 24 covers both second negative electrode bending portions 2363. In another embodiment of this example, as... Figures 14 to 15 There are two second negative electrode bending portions 2363. The reinforcing layer 24 does not cover the two second negative electrode bending portions 2363 and is located between the negative electrode coated active material region 232 and the second negative electrode bending portions 2363.

[0076] It should be noted that whether the reinforcing layer 24 can cover the second negative electrode bending portion 2363 depends on the hardness of the material of the reinforcing layer 24. The hardness of the reinforcing layer 24 can be adjusted by adjusting the proportion of ceramic particles contained in the reinforcing layer 24.

[0077] Specifically, when the proportion of ceramic particles is less than 10%, the reinforcing layer 24 is relatively soft and can bend along with the second negative electrode bending portion 2363, thereby covering the second negative electrode bending portion 2363. When the proportion of ceramic particles is 10%-90%, the reinforcing layer 24 is relatively hard and cannot bend along with the second negative electrode bending portion 2363, thus failing to cover the second negative electrode bending portion 2363.

[0078] In this embodiment, the reinforcing layer 24 is disposed in close contact with the negative electrode active material layer 2311 along the preset direction Q, that is, there is no gap between the reinforcing layer 24 and the negative electrode active material layer 2311. However, it is not limited to this. In other embodiments, a preset gap of non-zero may also be provided between the reinforcing layer 24 and the negative electrode active material layer 2311 along the preset direction Q.

[0079] Preferably, the grayscale value of the reinforcing layer 24 is 0-110. The grayscale value of the reinforcing layer 24 is 0-110, meaning that, preferably, the color of the reinforcing layer 24 is gray or black. Thus, by having the reinforcing layer 24 be gray or black, it can absorb the laser during laser cutting, avoiding laser reflection (e.g., when white), thereby reducing laser reflection and scattering. This results in more concentrated laser energy, making it easier to cut the current collector. Furthermore, it allows for cutting at relatively lower power, reducing the likelihood of burrs on the cut edge and minimizing the risk of short circuits within the battery cell caused by burrs.

[0080] When the grayscale value is closer to 0, the color of the reinforcing layer 24 is darker. Compared with the white reinforcing layer in the prior art, the reinforcing layer 24 in this embodiment has a much stronger absorption effect on laser. When the grayscale value is greater than 110, the color of the reinforcing layer 24 becomes whiter as the grayscale value increases, and the absorption effect of the reinforcing layer 24 on laser is weaker.

[0081] An image of the reinforcement layer 24 can be captured by a camera or sensor, and then the grayscale value of the image can be analyzed by computer software to obtain the actual grayscale value of the reinforcement layer 24.

[0082] Preferably, the ratio of the thickness t1 of the reinforcing layer 24 to the thickness t2 of the negative electrode current collector 231 is 1-6. By setting the range of values ​​for the ratio of the thickness t1 of the reinforcing layer 24 to the thickness t2 of the negative electrode current collector 231, the thickness of the reinforcing layer 24 can be controlled within a reasonable range. On the one hand, this avoids the ratio being too small, which would prevent the reinforcing layer 24 from providing adequate support; on the other hand, it avoids the ratio being too large, which would cause the radial dimension R of the winding structure 201 to be too large, thus affecting the energy density of the battery.

[0083] Preferably, the thickness t2 of the negative electrode current collector 231 is 4μm-5.5μm, for example, it can be 4μm, 4.3μm, 4.75μm, 5.0μm or 5.5μm. When the thickness t2 of the negative electrode current collector 231 is 4μm-5.5μm, the negative electrode current collector 231 is an ultra-thin current collector, which is prone to wrinkling. In this embodiment, by covering a portion of the preset region 2362 with a reinforcing layer 24, the support of the uncoated active material region 233 of the negative electrode during bending can be improved, solving the problem of wrinkling of the ultra-thin current collector. At the same time, the ultra-thin current collector can improve the volumetric energy density of the battery. Furthermore, by covering a portion of the preset region 2362 with a reinforcing layer 24, the bending position in the height direction H can be improved, thereby increasing the relative position of the welding area of ​​the uncoated active material region 233 of the negative electrode and the separator 22 in the height direction H, achieving the purpose of avoiding burns to the separator 22 during welding and improving the safety of the battery cell.

[0084] Specifically, at least a portion of the uncoated active material region 233 forms a negative electrode tab 237. Along the winding direction P of the winding structure 201, the uncoated active material region 233 sequentially includes a first uncoated active material region, a second uncoated active material region, and a third uncoated active material region, wherein the second uncoated active material region includes the negative electrode tab 237, while neither the first nor the third uncoated active material region includes the negative electrode tab 237.

[0085] Each negative electrode tab 237 located on the outermost ring is provided with a first negative electrode bending portion 2361 and a second negative electrode bending portion 2363. Thus, by setting the first negative electrode bending portion 2361, the negative electrode tab 237 is bent towards the central hole 2011 of the winding structure 201; by setting the second negative electrode bending portion 2363 in the preset area 2362, the preset area 2362 expands outward along the radial R of the winding structure 201, thereby preventing the negative electrode tab 237 from contacting the leaking part of the positive electrode current collector 211, thereby improving the safety of the battery cell; furthermore, by setting the preset area 2362 partially covered with a reinforcing layer 24, the support of the bending of the negative electrode tab 237 can be improved. Specifically, since the negative electrode tab 237 starts to bend at the first negative electrode bending portion 2361, by covering a portion of the preset area 2362 with a reinforcing layer 24, the position of the bend in the height direction H can be improved, thereby increasing the relative position of the welding area of ​​the negative electrode tab 237 and the separator 22 in the height direction H, achieving the purpose of avoiding burns to the separator 22 during welding, and further improving the safety of the battery cell.

[0086] Among them, the negative electrode tab 237 located on the outermost ring refers to the negative electrode tab 237 of the second negative electrode uncoated active material region located on the outermost ring of the winding ring formed by the uncoated active material region of the second negative electrode.

[0087] Along the winding direction P of the winding structure 201, adjacent negative electrode tabs 237 have a preset spacing. The negative electrode tabs 237 are trapezoidal in shape, with the lower base of the trapezoid close to the negative electrode active material coating area 232, and a reinforcing layer 24 covering the end of the negative electrode tab 237 near the negative electrode active material coating area 232. Thus, by setting a preset spacing between adjacent negative electrode tabs 237 along the winding direction P, the bending of the negative electrode tabs 237 can be better achieved. By setting the shape of the negative electrode tabs 237 as a trapezoid, with the lower base close to the negative electrode active material coating area 232, the number of layers of negative electrode tabs 237 formed in the radial direction R after bending is relatively uniform. Because the upper base of the trapezoidal negative electrode tab 23 is shorter than the lower base, the end of the negative electrode tab 23 near the upper base is narrower, so a certain amount of pressure is required to hold it in place when welding the negative electrode tab 23 to the current collector. A reinforcing layer 24 is covered at the end of the negative electrode tab 237 near the negative electrode coating active material area 232, which can effectively increase the strength of the negative electrode tab 23, avoid affecting the height of the electrode assembly 20, and prevent the negative electrode tab 23 from being too close to the welding surface (welding area) of the current collector and the diaphragm 22, thus avoiding burning the diaphragm 22.

[0088] It should be noted that the negative electrode tab 237 is trapezoidal in shape, meaning that when the negative electrode sheet 23 is in an unwound state, the negative electrode tab 237 is trapezoidal in shape, wherein the lower base of the trapezoid is longer than the upper base. Please refer to [reference needed]. Figure 7 Along a direction opposite to the preset direction Q, the negative electrode tab 237 includes a negative electrode flat portion 234 and at least a portion of the negative electrode transition portion 235 connected in sequence.

[0089] Along the height direction H of the winding structure 201, the positive electrode current collector 211 includes a positive electrode coated active material region 212 covered by the positive electrode active material layer 2111 and a positive electrode uncoated active material region 213 not covered by the positive electrode active material layer 2111. The positive electrode uncoated active material region 213 includes a positive electrode flat portion 214 away from the positive electrode coated active material region 212 and a positive electrode transition portion 215 connecting the positive electrode flat portion 214 and the positive electrode coated active material region 212. The positive electrode flat portion 214 extends radially R along the winding structure 201. The positive electrode transition portion 215 includes a positive electrode bending portion 216 at one end near the positive electrode flat portion 214, and the positive electrode transition portion 215 also includes a positive electrode upright portion 218 located between the positive electrode bending portion 216 and the positive electrode coated active material region 212. By providing the positive electrode bending portion 216, the positive electrode tab 217 is bent towards the central hole 2011 of the winding structure 201. At least a portion of the positive electrode uncoated active material region 213 forms a positive electrode tab 217.

[0090] It should be noted that the positive electrode bending portion 216 is arc-shaped. The positive electrode bending portion 216 includes a first positive electrode bending end point A1 and a second positive electrode bending end point A2. The first positive electrode bending end point A1 is the position where the tangent of the positive electrode bending portion 216 intersects with the extension direction of the positive electrode upright portion 218, and the second positive electrode bending end point A2 is the position where the tangent of the positive electrode bending portion 216 intersects with the extension direction of the positive electrode flat portion 214.

[0091] Similarly, the first negative electrode bending portion 2361 is arc-shaped. The first negative electrode bending portion 2361 includes a first negative electrode bending end point B1 and a second negative electrode bending end point B2. The first negative electrode bending end point B1 is the position where the tangent of the first negative electrode bending portion 2361 intersects with the extension direction of the preset area 2362, and the second negative electrode bending end point B2 is the position where the tangent of the first negative electrode bending portion 2361 intersects with the extension direction of the negative electrode flat portion 234.

[0092] Please refer to the following: Figure 1 and Figure 2 In this embodiment, the casing 10 of the cylindrical battery 1 includes a surrounding sidewall 12, and an opening 14 is formed at one end of the sidewall 12.

[0093] The cylindrical battery 1 also includes a cover plate 40 and a negative electrode current collector 62. The cover plate 40 is installed in the opening 14. The negative electrode current collector 62 is disposed between the electrode assembly 20 and the cover plate 40 and is electrically connected to the housing 10. One side of the connecting piece 621 of the negative electrode current collector 62 is welded to the negative electrode flat portion 234. In this way, by covering a portion of the predetermined area 2362 with a reinforcing layer 24, support force can be provided for the welding of the negative electrode current collector 62, avoiding insufficient welding contact force between the negative electrode tab 237 and the negative electrode current collector 62, which could lead to the generation of explosion points.

[0094] The cylindrical battery 1 also includes an insulating seal 50, which surrounds the periphery of the cover plate 40 to insulate and seal the cover plate 40 and the housing 10.

[0095] The housing 10 also includes a crimping portion 30, which is formed at one end of the side wall 12 near the opening 14 and recessed into the housing 10; the other side of the connecting piece 621 of the negative electrode current collector 62 is welded to the crimping portion 30. In this way, by setting the connecting piece 621 of the negative electrode current collector 62 to be located on the side of the crimping portion 30 facing the electrode assembly 20 and welded to the crimping portion 30, that is, the welding area of ​​the negative electrode current collector 62 with the electrode tab is located closer to the electrode assembly 20 than the crimping portion 30, thereby preventing the crimping portion 30 from affecting the welding area between the electrode tab and the negative electrode current collector 62, thereby improving the welding strength between the electrode tab and the negative electrode current collector 62.

[0096] Furthermore, the housing 10 also includes an end wall 11, and a side wall 12 is disposed around the end wall 11 and located at the end of the side wall 12 away from the opening 14. The end wall 11 and the side wall 12 enclose a receiving cavity 13 within the housing 10 for accommodating the electrode assembly 20, electrolyte, and other necessary battery components. The connection between the end wall 11 and the side wall 12 can be achieved in various ways, such as integral stamping, integral casting, or separate welding.

[0097] The cylindrical battery 1 also includes a terminal 70 that passes through the end wall 11 and is insulated from the end wall 11 by an insulator 80.

[0098] The cylindrical battery 1 also includes a positive current collector 61. The positive current collector 61 is disposed between the electrode assembly 20 and the end wall 11; the negative current collector 62 is disposed between the electrode assembly 20 and the cover plate 40. In this embodiment, the positive current collector 61 corresponds to the positive electrode tab 217, and the positive electrode tab 217 is electrically connected to the terminal post 70 through the positive current collector 61; the negative current collector 62 corresponds to the negative electrode tab 237, and the negative electrode tab 237 is electrically connected to the housing 10 through the negative current collector 62.

[0099] In this embodiment, the welding sequence of the positive current collector 61 and negative current collector 62 of the cylindrical battery 1 to the electrode assembly 20 is as follows: First, place the positive current collector 61; then, press the electrode assembly 20 together on both the positive and negative sides (the pressing process can increase the contact between the current collector and the electrode assembly 20 and avoid poor welding); the positive current collector 61 is welded using line welding instead of spot welding. This is because the negative electrode tab 237 is relatively soft, and after two pressings, the negative current collector 62 and the electrode assembly 20 will be closer together. Spot welding would cause the separator 22 to be burned due to concentrated heat. Wire welding has less heat and can avoid burning the separator 22, which would cause a short circuit between the positive and negative electrodes; next, place the negative current collector 62; press the electrode assembly 20 together on both the positive and negative sides again; finally, weld the negative current collector 62.

[0100] The cylindrical battery 1 in this embodiment has advantages such as high energy density, long cycle life and good safety performance.

[0101] In this embodiment, the negative electrode tab 237 is a folded tab. When welding the tabs and current collector of the cylindrical battery 1, the pretreatment steps for the tabs include two different methods: one is a flattening tab treatment method, and the other is the folded tab treatment method used for the negative electrode tab 237 in this embodiment. Similarly, the positive electrode tab 217 is also a folded tab.

[0102] like Figure 16As shown, this utility model also provides a battery pack 100, which includes the aforementioned cylindrical battery 1. In one embodiment of the battery pack 100, the battery pack 100 includes a housing 110, a cover 120, and multiple cylindrical batteries 1. The multiple cylindrical batteries 1 are placed in the housing 110 and connected in series or parallel, or a combination of series and parallel connections. The cover 120 seals the housing 110 to protect the multiple cylindrical batteries 1. It should be noted that, in addition to the cylindrical battery 1 of this utility model, the battery pack 100 may also include a thermal management system, circuit board, etc. The battery pack 100 can be a battery module, a battery pack, an energy storage cabinet, etc.; these will not be described in detail here.

[0103] like Figure 17 As shown, this utility model also provides an electronic device 1000, which includes the aforementioned battery pack 100. A working part 300 is electrically connected to the battery pack 100 to obtain electrical power. As an example, the electronic device 1000 is a vehicle, which can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, but are not limited thereto. The working part 300 is the vehicle body, and the battery pack 100 is located at the bottom of the vehicle body, providing electrical power for the vehicle's operation or the operation of its internal electrical components. However, in other embodiments, the electronic device 1000 can also be a mobile phone, portable device, laptop computer, ship, spacecraft, electric toy, and power tool, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc.; the working part 300 can be a unit component capable of obtaining electrical power from the battery pack 100 and performing corresponding work, such as a fan blade rotation unit or a vacuum cleaner suction unit. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric boat toys, and electric airplane toys, etc.; power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This application does not impose any special limitations on the aforementioned electronic device 1000.

[0104] Example 2

[0105] like Figure 18 As shown, the overall structure of the cylindrical battery 1 in this embodiment is basically the same as that in the embodiment. The difference is that a non-zero preset spacing G is provided between the reinforcing layer 24 and the negative electrode active material layer 2311, with the unit being mm.

[0106] Preferably, the preset spacing G is 0.1mm-1.1mm. By setting the range of the preset spacing G, on the one hand, it prevents the preset spacing G from being too large, which would result in insufficient welding area for the negative electrode tab 237; on the other hand, it avoids the preset spacing G from being too small, which would cause the reinforcing layer 24 and the negative electrode active material layer 2311 to fuse together and produce bulging edges, thus making the boundary between the reinforcing layer 24 and the negative electrode active material layer 2311 clear, improving battery performance and reducing safety hazards.

[0107] Preferably, the width of the uncoated active material region 233 of the negative electrode along the preset direction Q is W1, in mm; along the preset direction Q, there is a non-zero preset spacing G between the negative electrode active material layer 2311 and the reinforcing layer 24, in mm, satisfying 22≤W1 / G≤400. By controlling the ratio of W1 / G, the width of the uncoated active material region 233 and the preset spacing G are kept within a suitable range. On the one hand, this prevents the preset spacing G from being too large, resulting in insufficient welding area for the negative electrode tab 237, thus balancing the width of the uncoated active material region 233 and the preset spacing G; on the other hand, it avoids the preset spacing G from being too small, causing the reinforcing layer 24 and the negative electrode active material layer 2311 to fuse together and produce bulging edges, thereby making the boundary between the reinforcing layer 24 and the negative electrode active material layer 2311 clear, improving battery performance and reducing safety hazards.

[0108] Preferably, along the preset direction Q, the width of the negative electrode active material layer 2311 is W2, in mm, satisfying 3≤W2 / W1≤11.

[0109] The width W1 of the uncoated active material region 233 of the negative electrode is, for example, 30mm-40mm. By controlling the ratio of the width W2 of the negative electrode active material layer 2311 to the width W1 of the uncoated active material region 233, the widths of the negative electrode active material layer 2311 and the uncoated active material region 233 can be balanced while setting the reinforcing layer 24. This facilitates the bending of the uncoated active material region 233 to connect electrically with the electrode post 70, avoids flipping and wrinkling, and balances the mass energy density of the battery.

[0110] Example 3

[0111] like Figure 19 and Figure 20As shown, the overall structure of the cylindrical battery 1 in this embodiment is basically the same as that in the embodiment. The difference is that the cylindrical battery 1 in this embodiment does not include the pressing part in the embodiment. Instead, the outer periphery of the cover plate 40, the end of the side wall 12 of the shell 10 near the opening 14, and the outer periphery of the connecting piece 621 of the negative electrode current collector 62 are connected by welding. That is, the outer periphery of the cover plate 40, the end of the shell 10, and the outer periphery of the connecting piece 621 of the negative electrode current collector 62 are directly connected together by welding. On the one hand, this can make the connection of the three more solid; on the other hand, it can realize the one-step welding assembly of the negative electrode current collector 62, the cover plate 40, and the shell 10, thereby improving the production efficiency of the battery.

[0112] Furthermore, in conjunction with the reinforcing layer 24 mentioned above covering a portion of the preset area 2362, the strength of the negative electrode tab 237 is increased by setting the reinforcing layer 24, thereby increasing the distance between the welding area and the diaphragm 22 and preventing the diaphragm 22 from being burned during welding.

[0113] Specifically, the outer periphery of the cover plate 40, the end of the housing 10, and the outer periphery of the connecting piece 621 are fused together by laser welding.

[0114] While specific embodiments of this utility model have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of this utility model is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of this utility model, but all such changes and modifications fall within the scope of protection of this utility model.

Claims

1. A cylindrical battery, characterized in that, It includes: case; An electrode assembly is housed within the housing. The electrode assembly includes a positive electrode sheet, a separator, and a negative electrode sheet stacked and wound together to form a wound structure. The positive electrode sheet includes a positive current collector, and the negative electrode sheet includes a negative current collector. Along the height direction of the wound structure, the negative current collector includes a negative electrode coated active material region covered by a negative electrode active material layer and a negative electrode uncoated active material region not covered by the negative electrode active material layer. The uncoated active material region of the negative electrode includes a negative electrode flat portion away from the negative electrode coated active material region, and a negative electrode transition portion connecting the negative electrode flat portion and the negative electrode coated active material region. The negative electrode flat portion extends radially along the winding structure. The direction from the negative electrode coated active material region to the uncoated active material region of the negative electrode is a preset direction. The negative electrode transition portion includes a first negative electrode bend portion and a preset region connected in a direction opposite to the preset direction. The preset area includes a second negative electrode bending portion, and the preset area is partially covered with a reinforcing layer.

2. The cylindrical battery as described in claim 1, characterized in that, Along the radial direction of the winding structure, the preset region includes a first negative electrode side away from the central hole of the winding structure and a second negative electrode side facing the central hole, wherein at least a portion of the first negative electrode side and / or the second negative electrode side is covered by the reinforcing layer.

3. The cylindrical battery as described in claim 1, characterized in that, The reinforcing layer covers the bent portion of the second negative electrode; or... The reinforcing layer does not cover the second negative electrode bending portion and is located between the negative electrode coated active material area and the second negative electrode bending portion.

4. The cylindrical battery as described in claim 1, characterized in that, The number of second negative electrode bends is one, the bending direction of the second negative electrode bend is different from that of the first negative electrode bend, and they are arranged opposite to each other along the radial direction; or, There are multiple second negative electrode bending portions, which are arranged sequentially along the preset direction. The bending directions of adjacent second negative electrode bending portions are different. The second negative electrode bending portion closest to the first negative electrode bending portion has a different bending direction from the first negative electrode bending portion and is arranged opposite to it along the radial direction.

5. The cylindrical battery according to claim 1, characterized in that, The width of the uncoated active material area of ​​the negative electrode along the preset direction is W1, in mm; Along the predetermined direction, the negative electrode active material layer and the reinforcing layer have a non-zero predetermined spacing G, in mm, satisfying 22 ≤ W1 / G ≤ 400; and / or, Along the preset direction, the width of the negative electrode active material layer is W2, in mm, which satisfies 3≤W2 / W1≤11.

6. The cylindrical battery according to claim 5, characterized in that, The preset spacing G is 0.1mm-1.1mm.

7. The cylindrical battery according to claim 1, characterized in that, The ratio of the thickness of the reinforcing layer to the thickness of the negative electrode current collector is 1-6, or the thickness of the current collector is 4μm-5.5μm; And / or, The grayscale value of the reinforcing layer is 0-110; And / or, At least a portion of the negative electrode uncoated active material area forms a negative electrode tab, and each negative electrode tab located on the outermost ring is provided with a first negative electrode bending portion and a second negative electrode bending portion.

8. The cylindrical battery according to any one of claims 1-7, characterized in that, The housing includes surrounding sidewalls, one end of which is formed with an opening; The cylindrical battery also includes: Cover plate, installed in the opening; A negative electrode current collector is disposed between the electrode assembly and the cover plate and is electrically connected to the housing. One side of the connecting piece of the negative electrode current collector is welded to the flat part of the negative electrode. The housing further includes a crimping portion, which is formed on one end of the side wall near the opening and recessed into the housing; the other side of the connecting piece of the negative electrode current collector is welded to the crimping portion. or, The outer periphery of the cover plate, the end of the side wall of the housing near the opening, and the outer periphery of the connecting piece of the negative electrode current collector are connected by welding.

9. A battery pack, characterized in that, The cylindrical battery includes any one of claims 1 to 8.

10. An electronic device, characterized in that, Includes the battery pack as described in claim 9.

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