Secondary battery, battery pack, and electronic device

Abstract

The utility model provides a secondary battery, a battery pack and an electronic device. The secondary battery comprises a shell, an electrode assembly, a pole and lower plastic, the shell comprises an end wall, the electrode assembly is arranged in the shell, the pole penetrates through the end wall and is insulated from the end wall, and the lower plastic cement is arranged on one side, facing the electrode assembly, of the end wall; the lower plastic comprises a first part and a second part, the first part is clamped between the end wall and the pole, and the second part is arranged on the periphery of the first part in a surrounding manner; wherein the second part comprises a hollowed-out area and a non-hollowed-out area, and the projection area of the hollowed-out area is larger than that of the non-hollowed-out area in the thickness direction of the lower plastic. According to the utility model, the corrosion degree of electrolyte to the end wall can be improved, and the risk of short circuit in the secondary battery is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to a battery technical field, concretely relates to a secondary battery, battery pack and electronic device. BACKGROUND

[0002] In the prior art, in order to realize the insulation between the end wall and the electrode assembly, the lower plastic is usually arranged between the end wall and the electrode assembly. The lower plastic is generally fixed on the end wall by the flange of the pole column located inside the shell. However, this design inevitably causes a certain contact gap between the lower plastic and the end wall.

[0003] When the electrolyte seeps into the contact gap between the lower plastic and the end wall, under the condition of high temperature for a long time, the end wall may be corroded. If the corrosion product generated in the corrosion process enters the inside of the electrode assembly, it may cause internal short circuit of the secondary battery, affecting the safety of the secondary battery. SUMMARY

[0004] The utility model provides a secondary battery, battery pack and electronic device to improve the corrosion degree of electrolyte to the end wall, reduce the risk of internal short circuit of the secondary battery.

[0005] To achieve the above object and other related purposes, the utility model provides a secondary battery, which comprises a shell, an electrode assembly, a pole column and a lower plastic. The shell comprises an end wall; the electrode assembly is arranged in the shell; the pole column is installed through the end wall and is insulated from the end wall; the lower plastic is arranged on the side of the end wall facing the electrode assembly; the lower plastic comprises a first part and a second part, the first part is clamped between the end wall and the pole column, and the second part is arranged around the outer periphery of the first part; wherein the second part comprises a hollow area and a non-hollow area, and the projection area of the hollow area is greater than that of the non-hollow area along the thickness direction of the lower plastic.

[0006] In an example of the secondary battery of the utility model, the hollow area comprises a plurality of hollow units, and the plurality of hollow units are arranged at intervals along the circumferential direction of the second part.

[0007] In an example of the secondary battery of the utility model, the second part comprises a body part and a thickened part, and the thickened part is arranged on the side of the body part facing the electrode assembly; along the thickness direction of the lower plastic, the hollow area penetrates through the body part and the thickened part.

[0008] In an example of the secondary battery of the utility model, the thickness of the thickened part is 0.4-0.8mm.

[0009] In an example of the secondary battery of the utility model, on the side of the end wall facing the electrode assembly, the maximum distance between the lower plastic and the end wall is less than the maximum distance between the pole column and the end wall.

[0010] In the secondary battery example of the utility model, the thickness of the first part is less than the maximum thickness of the second part.

[0011] In the secondary battery example of the utility model, the secondary battery further comprises a current collecting member, the current collecting member is arranged between the end wall and the electrode assembly and is electrically connected with the electrode assembly; along the thickness direction of the lower plastic, a minimum gap h1 is formed between the current collecting member and the lower plastic, and 0 < h1 ≤ 0.2 mm.

[0012] In the secondary battery example of the utility model, the current collecting member is of solid structure.

[0013] In the secondary battery example of the utility model, the current collecting member comprises a current collecting body and a pole connecting area, the current collecting body is arranged around the outer periphery of the pole connecting area, and the pole connecting area is electrically connected with the pole; the secondary battery further comprises a first insulating tape, the first insulating tape comprises a first adhesive area and a second adhesive area, the first adhesive area is wrapped on the outer periphery surface of the electrode assembly on the side of the end wall, and the second adhesive area is wrapped on the current collecting body; the projection of the part of the pole in the inside of the shell along the thickness direction of the lower plastic covers the pole connecting area.

[0014] In the secondary battery example of the utility model, the first adhesive area or the second adhesive area comprises a plurality of cutouts, and the plurality of cutouts divide the first adhesive area or the second adhesive area into a plurality of mutually connected adhesive strips.

[0015] In the secondary battery example of the utility model, the secondary battery further comprises a second insulating tape, the outer periphery surface of the electrode assembly comprises a bare diaphragm layer, and the winding tail end of the diaphragm layer is fixed by the second insulating tape.

[0016] The utility model also provides a kind of battery pack, and the battery pack includes the secondary battery of any one of the above.

[0017] The utility model also provides an electronic device, and the electronic device includes the battery pack.

[0018] In the secondary battery of the utility model, the second part of the lower plastic is provided with a hollow area and a non-hollow area, and the projection area of the hollow area is greater than the projection area of the non-hollow area. This design can form a larger hollow area between the lower plastic and the end wall, increase the discontinuity of the contact area of the two, thereby facilitating the outflow of electrolyte infiltrated between the lower plastic and the end wall, reducing the accumulation of electrolyte between the end wall and the lower plastic. By reducing the accumulation of electrolyte, the degree of corrosion of electrolyte on the end wall can be effectively reduced, the risk of corrosion products entering the inside of the electrode assembly is reduced, and the risk of internal short circuit of the secondary battery is reduced, thereby improving the safety performance of the secondary battery. BRIEF DESCRIPTION OF DRAWINGS

[0019] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is an axial sectional view of an example of a secondary battery according to this utility model;

[0021] Figure 2 for Figure 1 A magnified view of a portion of region A in the middle;

[0022] Figure 3 This is a schematic diagram of the electrode assembly structure of an example of the secondary battery of this utility model;

[0023] Figure 4 This is a partial structural diagram of an example of a secondary battery of the present invention, showing an electrode assembly with a first insulating tape on the side facing the end wall.

[0024] Figure 5 This is a schematic diagram showing the installation position of the electrode post on the end wall in an example of the secondary battery of this utility model;

[0025] Figure 6 This is a three-dimensional structural diagram of the lower plastic in an example of a secondary battery of this utility model;

[0026] Figure 7 This is a projection view of the lower plastic part of an example of a secondary battery of this utility model from another angle.

[0027] Figure 8 for Figure 7 Cross-sectional view along the BB direction;

[0028] Figure 9 This is a schematic diagram showing the bonding position of the first insulating tape on the electrode assembly in an example of the secondary battery of this utility model;

[0029] Figure 10 This is a schematic diagram showing the bonding position of the second bonding area on the current collector in an example of the secondary battery of this utility model;

[0030] Figure 11 This is a schematic diagram of the bonding position of the first bonding area on the outer peripheral surface of the electrode assembly in an example of the secondary battery of this utility model;

[0031] Figure 12 This is a schematic diagram showing the location of the first incision in the first bonding area in an example of the secondary battery of this utility model.

[0032] Figure 13The utility model discloses a secondary battery one example in the position schematic view of setting up second cutout in second adhesive area,

[0033] Figure 14 The utility model discloses a secondary battery one example in the plan view of current collecting member,

[0034] Figure 15 For Figure 14 The utility model discloses a secondary battery one example in the section schematic drawing of C-C direction,

[0035] Figure 16 The utility model discloses a secondary battery one example in the winding structure schematic view of setting up diaphragm layer to the outer periphery of electrode assembly,

[0036] Figure 17 The utility model discloses a secondary battery one example in the structure schematic view of the winding tail end of diaphragm layer is adhered with second insulating tape,

[0037] Figure 18 The utility model discloses a battery pack one example's schematic diagram,

[0038] Figure 19 The utility model discloses an electronic device one example's schematic diagram.

[0039] Element number explanation:

[0040] 100, secondary battery, 110, shell, 111, end wall, 112, side wall, 113, opening, 114, cover plate, 120, electrode assembly, 121, positive plate, 1211, positive current collector, 1212, first coating area, 1213, first non-coating area, 122, diaphragm, 123, negative plate, 1231, negative current collector, 1232, second coating area, 1233, second non-coating area, 124, negative tab, 125, positive tab, 130, lower plastic, 131, first part, 132, second part, 1321, hollow area, 13211, hollow unit, 1322, body part, 1323, thickening part, 1324, non-hollow area, 133, stage, 140, current collecting member, 141, current collecting body, 142, pole connecting area, 150, first insulating tape, 151, first adhesive area, 152, second adhesive area, 1531, first cutout, 1532, second cutout, 154, adhesive strip, 155, adhesive overlap area, 160, second insulating tape, 170, diaphragm layer, 171, winding tail end, 180, pole, 181, columnar part, 182, outer flange, 183, inner flange, 191, upper plastic, 192, sealing element, 200, battery pack, 210, box, 211, first box part, 212, second box part, 300, electronic device, 310, working part. DETAILED DESCRIPTION

[0041] The above and other advantages and effects of the present application will become readily apparent to those of ordinary skill in the art from the following description in conjunction with the accompanying drawings. The present application can also be put into practice in various ways, and the details of the specification can be modified in different ways without departing from the spirit of the present application. It should be noted that the embodiments below and the features in the embodiments can be combined with each other without conflict. It should also be understood that the terms used in the embodiments of the present application are intended to describe specific embodiments, and are not intended to limit the scope of protection of the present application. The test methods not specified in the following embodiments are generally performed under conventional conditions or under conditions recommended by the manufacturers.

[0042] When the embodiments give a numerical range, it should be understood that, unless otherwise stated by the present application, each numerical range and any number between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present application are used by those skilled in the art and the present application, and any method, equipment and material of the prior art similar or equivalent to the method, equipment and material of the embodiments of the present application can be used to realize the present application.

[0043] It should be noted that the terms such as "up", "down", "left", "right", "middle" and "one" used in the specification are only for the convenience of clear description, and are not intended to limit the scope of the present application. The change or adjustment of the relative relationship, without substantial change of the technical content, is also regarded as the scope of the present application.

[0044] Please refer to Figures 1 to 19 The secondary battery 100, the battery pack 200 and the electronic device 300 provided by the present application can reduce the accumulation of electrolyte between the end wall 111 and the lower plastic 130 by setting the hollow area 1321 on the lower plastic 130 and limiting the projection area of the hollow area 1321 to be greater than the projection area of the non-hollow area, thereby reducing the corrosion degree of the electrolyte on the end wall 111, so as to reduce the risk of internal short circuit of the secondary battery 100 and improve the safety performance of the secondary battery 100.

[0045] Please refer to Figure 1 And Figure 2 The secondary battery 100 provided by the present application comprises a shell 110, an electrode assembly 120, a pole 180 and a lower plastic 130.

[0046] Please refer to Figure 1 And Figure 2The shell 110 includes an end wall 111 and a side wall 112 surrounding the end wall 111. The connection between the end wall 111 and the side wall 112 can be achieved in various ways, such as one-piece stamping, one-piece casting or separate welding, as long as a stable sealing and electrical connection relationship can be formed. The side wall 112 can surround in a cylindrical or prismatic shape, or any other closed-loop profile that can match the end wall 111. In the embodiment, the outer edge of the end wall 111 is circular, and the side wall 112 surrounds the outer edge of the end wall 111 in a cylindrical shape, and a circular opening 113 is formed at the end of the side wall 112 away from the end wall 111. The end wall 111 and the side wall 112 form a housing 110 inside which an electrode assembly 120, an electrolyte and other necessary components of the battery are accommodated. Specifically, the diameter of the shell 110 can be determined according to the specific size of the electrode assembly 120, such as 18mm, 21mm, 46mm, etc. The shell 110 can be made of various materials, such as copper, iron, aluminum, steel, aluminum alloy, etc. In order to prevent rusting of the shell 110 during long-term use, a layer of anti-rust material such as metal nickel can be plated on the surface of the shell 110.

[0047] Referring to Figures 1 to 3 The electrode assembly 120 is arranged inside the shell 110, and the electrode assembly 120 is a component that undergoes an electrochemical reaction in the secondary battery 100. The shell 110 can contain one or more electrode assemblies 120. The electrode assembly 120 includes a tab and a separator 122, and the tab and the separator 122 are wound to form a wound structure. Specifically, in the embodiment, the electrode assembly 120 includes a positive electrode tab 121, a separator 122 and a negative electrode tab 123 wound axially around the shell 110.

[0048] Referring to Figure 1 and Figure 3 The positive electrode tab 121 includes a positive electrode current collector 1211 and a positive electrode active material layer coated on the positive electrode current collector 1211. The positive electrode current collector 1211 has a first coated area 1212 coated with the positive electrode active material layer and a first uncoated area 1213 not coated with the positive electrode active material layer. The first coated area 1212 and the first uncoated area 1213 are arranged axially along the shell 110. The first uncoated area 1213 extends to the outside of the separator 122 at one end of the secondary battery 100 in the height direction, and is bent towards the axis of the shell 110 to form a stacked positive electrode tab 125.

[0049] The negative electrode sheet 123 includes a negative electrode current collector 1231 and a negative electrode active material layer coated on the negative electrode current collector 1231, and a second coated area 1232 coated with the negative electrode active material layer and a second uncoated area 1233 not coated with the negative electrode active material layer are formed on the negative electrode current collector 1231, the second coated area 1232 and the second uncoated area 1233 are arranged axially along the shell 110, the second uncoated area 1233 extends to the outside of the diaphragm 122 towards the other end of the height direction of the secondary battery 100, and is bent towards the axis of the shell 110 to form a stacked negative electrode tab 124.

[0050] The diaphragm 122 is arranged between the positive electrode sheet 121 and the negative electrode sheet 123 to separate the positive electrode active material layer and the negative electrode active material layer. Taking the lithium ion secondary battery 100 as an example, the material of the positive electrode current collector 1211 can be aluminum, the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material can be lithium cobaltate, lithium iron phosphate, ternary lithium or lithium manganate, etc. The material of the negative electrode current collector 1231 can be copper, the negative electrode active material layer includes a negative electrode active material, and the negative electrode active material can be carbon or silicon, etc. The base material of the diaphragm 122 can be polypropylene (PP) or polyethylene (PE), etc. In order to protect and insulate the electrode assembly 120, an insulating film can also be wrapped outside the electrode assembly 120, and the insulating film can be synthesized by PP, PE, polyethylene terephthalate (PET), polyvinyl chloride (PVC) or other high molecular polymer materials.

[0051] Please refer to Figures 1 to 3 , further, the positive electrode tab 125 in the utility model faces the end wall 111 or faces the opening 113, then the negative electrode tab 124 faces the other end of the shell 110. Alternatively, in the embodiment, the positive electrode tab 125 faces the end wall 111, and is electrically connected with the pole 180 to make the pole 180 positively charged, and the negative electrode tab 124 faces the opening 113, and the shell 110 is electrically connected with the negative electrode tab 124, so as to be negatively charged. However, in another embodiment, the negative electrode tab 124 can be connected with the pole 180, and the positive electrode tab 125 can be connected with the shell 110.

[0052] Please refer to Figure 1 The secondary battery 100 further includes a cover plate 114, and the cover plate 114 is sealingly installed in the opening 113. The outer edge of the cover plate 114 corresponds in shape to the shape of the opening 113, and is connected with the side wall 112 to seal the opening 113, and the installation mode of the cover plate 114 includes but is not limited to mechanical sealing or welding sealing, and in the embodiment, the cover plate 114 is sealingly sealed on the opening 113 in a mechanical sealing mode.

[0053] Please refer to Figure 2 and Figure 5 The pole post 180 is installed through the end wall 111 and is insulated from the end wall 111. The end of the pole post 180 towards the electrode assembly 120 penetrates the end wall 111 and can be directly electrically connected with the positive electrode tab 125 or indirectly electrically connected with the positive electrode tab 125 through the current collecting member 140. Optionally, in the embodiment, the side of the electrode assembly 120 towards the end wall 111 is provided with the current collecting member 140, which includes a current collecting body 141 and a pole post connecting area 142, and the current collecting body 141 is arranged around the outer periphery of the pole post connecting area 142. The current collecting body 141 is electrically connected with the positive electrode tab 125, and the pole post connecting area 142 is electrically connected with the pole post 180.

[0054] Please refer to Figure 5 The pole post 180 includes a columnar portion 181, an outer flange 182 and an inner flange 183, and the outer flange 182 and the inner flange 183 are respectively arranged at the two ends of the columnar portion 181 in the length direction. The columnar portion 181 penetrates the end wall 111, the outer flange 182 is located outside the shell 110 and extends from the columnar portion 181 to the outer periphery of the end wall 111. The inner flange 183 is located inside the shell 110 and extends from the columnar portion 181 to the outer periphery of the end wall 111. It should be noted that the inner flange 183 can be formed in various ways, for example, it can be a block structure welded separately on the columnar portion 181, or it can be a flange structure formed during the riveting of the lower edge of the columnar portion 181. Optionally, in the embodiment, the inner flange 183 is a flange structure formed during the riveting of the pole post 180.

[0055] Optionally, in an embodiment, the secondary battery 100 can further include an upper plastic 191 and a sealing member 192. The sealing member 192 is arranged around the outer periphery of the columnar portion 181 and is clamped between the end wall 111 and the outer flange 182. The upper plastic 191 is arranged around the outer periphery of the sealing member 192, the outer edge of the upper plastic 191 covers the outer periphery of the outer flange 182, and at least part of the upper plastic 191 extends into the space between the outer flange 182 and the end wall 111 to achieve insulation between the outer periphery of the outer flange 182 and the end wall 111.

[0056] Please refer to Figure 2 and Figure 5 The lower plastic 130 is arranged on the side of the end wall 111 towards the electrode assembly 120 to achieve insulation between the end wall 111 and the electrode assembly 120. The lower plastic 130 includes a first portion 131 and a second portion 132, the first portion 131 is clamped between the end wall 111 and the pole post 180, and the second portion 132 is arranged around the outer periphery of the first portion 131. Specifically, please refer to Figures 6 to 8The lower plastic 130 is annular in structure, and the inner edge region of the lower plastic 130 forms a first portion 131 clamped between the end wall 111 and the inner flange 183 of the pole 180. A second portion 132 is the region of the lower plastic 130 other than the first portion 131, i.e., the region extending from the outer periphery of the first portion 131 in the radial direction of the lower plastic 130 towards the outer periphery of the end wall 111. It is to be noted that the second portion 132 can be in full contact with the end wall 111 or in partial contact. In the present embodiment, the lower plastic 130 is at least partially in contact with the end wall 111. Such arrangement can ensure the insulation performance between the lower plastic 130 and the end wall 111, and avoid the problem of insulation failure due to excessive gap.

[0057] Please refer to Figure 6 and Figure 7 The second portion 132 includes a hollowed region 1321 and a non-hollowed region 1324. In the thickness direction of the lower plastic 130, the projection area of the hollowed region 1321 is greater than that of the non-hollowed region 1324, and the non-hollowed region 1324 is at least partially in contact with the end wall 111. The shape of the hollowed region 1321 is not limited, for example, it can be a circular hole, a sector, a long slot, etc. The hollowed region 1321 can be a whole continuous structure or a combination of multiple spaced independent hollowed units 13211. In actual design and production, the structure strength and insulation performance requirements of the lower plastic 130 need to be determined.

[0058] In the present embodiment, the second portion 132 of the lower plastic 130 is provided with the hollowed region 1321 and the non-hollowed region 1324, and the projection area of the hollowed region 1321 is greater than that of the non-hollowed region. Such design can form a larger hollowed region 1321 between the lower plastic 130 and the end wall 111. When the lower plastic 130 is in contact with the end wall 111, only the non-hollowed region 1324 can be in contact with the end wall 111, thereby reducing the contact area between the lower plastic 130 and the end wall 111 and increasing the discontinuity of the contact area. Such structure is conducive to the outflow of the electrolyte infiltrated between the lower plastic 130 and the end wall 111, and reduces the accumulation of electrolyte between the end wall 111 and the lower plastic 130. By reducing the accumulation of electrolyte, the corrosion degree of the electrolyte on the end wall 111 can be effectively reduced, the risk of corrosion products entering the inside of the electrode assembly 120 is reduced, and the risk of internal short circuit of the secondary battery 100 is reduced, thereby improving the safety performance of the secondary battery 100.

[0059] To further reduce the accumulation of electrolyte between the end wall 111 and the lower plastic 130, optionally, please refer to Figure 6 and Figure 7In the secondary battery 100 example of the utility model, the hollow region 1321 includes multiple hollow units 13211, and the multiple hollow units 13211 are arranged at intervals along the circumferential direction of the second part 132. The hollow unit 13211 can be circular, sectorial, elliptical or other geometric shapes. Optionally, in the embodiment, the hollow unit 13211 is a sectorial structure. This facilitates the formation of a larger hollow region 1321 on the lower plastic 130. The multiple hollow units 13211 can be uniformly distributed along the circumferential direction of the second part 132, or they can be unevenly distributed. Optionally, in the embodiment, the multiple hollow units 13211 are uniformly distributed along the circumferential direction of the second part 132. This not only facilitates the positioning and processing of the multiple hollow units 13211, but also ensures the uniformity of the overall support strength of the second part 132.

[0060] By arranging multiple hollow units 13211 distributed at intervals, an interlaced mesh or strip distribution structure can be formed between the non-hollow region 1324 and the hollow unit 13211, which can effectively disperse the contact area between the lower plastic 130 and the end wall 111, thereby reducing the accumulation of electrolyte in a certain area and reducing the risk of local corrosion of the end wall 111. In addition, since the multiple hollow units 13211 can form multiple micro-channels in the circumferential direction of the lower plastic 130, the flow path of the electrolyte at the position of the end wall 111 can be increased, thereby facilitating the rapid flow of infiltrated electrolyte.

[0061] When the lower plastic 130 is provided with a hollow region 1321, in order to ensure the insulation performance between the end wall 111 and the electrode assembly 120, optionally, please refer to Figures 6 to 8 In the secondary battery 100 example of the utility model, the second part 132 includes a body part 1322 and a thickened part 1323. The body part 1322 is arranged around the outer periphery of the first part 131. The body part 1322 can be arranged with the same thickness as the first part 131 in the thickness direction, or it can be arranged with different thicknesses. Optionally, please refer to Figure 8 In the embodiment, the thickness of the body part 1322 is the same as the thickness of the first part 131, and the surface of the body part 1322 towards the side of the end wall 111 is flush with the surface of the first part 131 towards the side of the end wall 111. This arrangement facilitates effective bonding between the lower plastic 130 and the end wall 111.

[0062] In particular, please refer to Figure 2 , Figure 6 and Figure 8The body part 1322 is approximately annular structure, the inner ring wall of the body part 1322 is connected with the outer periphery of the first part 131, and the outer ring wall of the body part 1322 extends towards the outer periphery of the end wall 111. The side of the body part 1322 towards the end wall 111 is at least partially in contact with the end wall 111. The thickening part 1323 is arranged on the side of the body part 1322 towards the electrode assembly 120. The thickening part 1323 can be integrally injection molded with the body part 1322, or can be fixedly connected by bonding. The shape of the thickening part 1323 is not limited, for example, it can be a whole annular structure, a plurality of block structures arranged along the circumferential direction of the lower plastic 130, etc. Optionally, please refer to Figure 5 and Figure 8 In the embodiment, the thickening part 1323 is an annular protruding structure arranged on the body part 1322. In the central region of the lower plastic 130, the thickening part 1323, the body part 1322 and the first part 131 are surrounded to form a platform stage 133, and when the lower plastic 130 is fixed with the pole column 180, the inner flange 183 of the pole column 180 is accommodated in the platform stage 133. In this way, the height space of the pole column 180 in the shell 110 is reduced when it is installed inside the shell 110, and the volume energy density of the secondary battery 100 is improved. Please refer to Figure 6 The hollow region 1321 penetrates the body part 1322 and the thickening part 1323 along the thickness direction of the lower plastic 130.

[0063] By arranging the thickening part 1323, on the one hand, the thickness of the material at the position around the hollow region 1321 can be increased, so that the overall support strength of the lower plastic 130 can be increased, and the stability of the insulation performance of the lower plastic 130 can be ensured. On the other hand, the creepage distance between the electrode assembly 120 and the end wall 111 can also be increased, so as to avoid the probability of insulation failure due to too small creepage distance when the electrode assembly 120 contacts the lower plastic 130.

[0064] Optionally, in an example of the secondary battery 100 of the utility model, the thickness of the thickening part 1323 is h2, h2 is any value in the range of 0.4-0.8 mm, for example, h2 can be 0.4 mm, 0.6 mm or 0.8 mm, etc. By limiting the thickness of the thickening part 1323 to be between 0.4-0.8 mm, on the one hand, the requirements of the support strength and the overall quality of the lower plastic 130 can be considered, so as to prevent the waste of materials and the influence on the mass density of the secondary battery 100 caused by too large mass. On the other hand, when the thickness of the thickening part is 0.4-0.8 mm, the lower plastic 130 and the electrode assembly 120 can have a better assembly gap, so as to ensure the assembly quality of the secondary battery 100 on the side of the pole column 180.

[0065] Optionally, please refer to Figure 2In the secondary battery 100 example of the utility model, on the side of end wall 111 towards electrode assembly 120, the maximum distance between lower plastic 130 and end wall 111 is h3, the maximum distance between pole 180 and end wall 111 is h4, and h3 is less than h4.It needs to be explained that the maximum distance h3 between lower plastic 130 and end wall 111 refers to the distance between the surface of thickening portion 1323 towards the side of electrode assembly 120 and the surface of end wall 111 towards the side of electrode assembly 120.The maximum distance h4 between pole 180 and end wall 111 refers to the distance between the highest point of inner flange 183 towards the side of electrode assembly 120 and the surface of end wall 111 towards the side of electrode assembly 120.Setting like this can avoid the contact between current collecting member 140 and lower plastic 130 during assembly, reduce assembly interference, and thus better ensure the stable contact between current collecting member 140 and pole 180.

[0066] Considering the different installation positions and functions of first portion 131 and second portion 132 of lower plastic 130, optionally, please refer to Figure 8 In the secondary battery 100 example of the utility model, the thickness of first portion 131 is less than the maximum thickness of second portion 132.Specifically, the thickness of first portion 131 is h5, the maximum thickness of second portion 132 is h6, and h5 is less than h6.It needs to be explained that the maximum thickness h6 of second portion 132 is the sum of the thicknesses of body portion 1322 and thickening portion 1323.Setting like this, on the one hand, because the thickness of first portion 131 is small, it is beneficial to reduce the height space occupied by the installation position of pole 180 inside shell 110 and improve the volume energy density of secondary battery 100.On the other hand, because the thickness of second portion 132 is large, it can increase the creepage distance between second portion 132 and current collecting member 140 and ensure the insulation performance between electrode assembly 120 and end wall 111.

[0067] Considering that the area of hollow region 1321 on lower plastic 130 is large, when current collecting member 140 deforms greatly towards the side of end wall 111, it may enter the inside of hollow region 1321, leading to the insulation failure between current collecting member 140 and end wall 111.Based on this, optionally, please refer to Figure 2 In the secondary battery 100 example of the utility model, along the thickness direction of lower plastic 130, minimum gap h1 is formed between current collecting member 140 and lower plastic 130, and 0 Figure 2As shown. By limiting the minimum gap h1 between the current collecting member 140 and the lower plastic 130, 0 < h1 ≤ 0.2 mm, the deformation of the current collecting member 140 can be limited by the lower plastic 130, so that the current collecting member 140 can be within a reasonable deformation range, and the probability of the current collecting member 140 extending into the hollow area 1321 due to excessive deformation can be reduced, thereby ensuring the insulation distance between the current collecting member 140 and the end wall 111, and improving the stability of the insulation performance therebetween.

[0068] To further improve the insulation performance between the electrode assembly 120 and the end wall 111, optionally, refer to Figure 4 and Figure 9 In an example of the secondary battery 100 of the utility model, the secondary battery 100 further comprises a first insulating tape 150, the first insulating tape 150 comprises a first adhesive area 151 and a second adhesive area 152, the first adhesive area 151 is wrapped on the outer circumferential surface of the electrode assembly 120 on the side of the end wall 111, and the second adhesive area 152 is wrapped on the current collecting body 141. The first insulating tape 150 can be made of an insulating material resistant to high temperature and electrolyte corrosion, such as a polyimide (PI) tape or a polytetrafluoroethylene (PTFE) tape. Under the condition of meeting the insulation requirement and the adhesive strength, the embodiment is not limited thereto. It should be noted that the unfolded shape of the first insulating tape 150 can be a circular ring sheet structure, or a rectangular strip structure, etc. In the actual production process, the unfolded structure of the first insulating tape 150 needs to be determined according to the production process of the secondary battery 100.

[0069] Please refer to Figure 4 The projection of the part of the pole 180 inside the shell 110 along the thickness direction of the lower plastic 130 covers the pole connecting area 142. Specifically, in the embodiment, the projection of the part of the pole 180 inside the shell 110 along the thickness direction of the lower plastic 130 refers to the circular projection formed by the cylindrical part 181 and the inner flange 183 inside the shell 110 along the thickness direction of the lower plastic 130. The circular projection covers the projection of the pole connecting area 142, that is, the second adhesive area 152 extends to the inside of the projection of the inner flange 183 along the radial direction of the lower plastic 130.

[0070] By covering the outer circumferential surface of the electrode assembly 120 with the first adhesive area 151, the electrical short circuit between the electrode assembly 120 and the shell 110 or the end wall 111 can be prevented, and the insulation performance between the electrode assembly 120 and the side wall 112 can be improved. By covering the current collecting body 141 with the second adhesive area 152, not only the stable connection between the current collecting member 140 and the electrode assembly 120 can be improved, and the contact resistance can be reduced, but also the probability of the electrical short circuit between the current collecting member 140 and the end wall 111 can be reduced, and the insulation performance between the current collecting member 140 and the end wall 111 can be improved. In addition, since the projection of the portion of the pole 180 inside the shell 110 along the thickness direction of the lower plastic 130 covers the pole connecting area 142, the side of the second adhesive area 152 close to the pole connecting area 142 can extend to the projection area of the inner flange 183, so that when the electrode assembly 120 or the end wall 111 is deformed and the pole 180 is displaced radially, the current collecting member 140 and the end wall 111 can not be in direct contact, so as to ensure the insulation effect between the end wall 111 and the current collecting member 140. Furthermore, since the first insulation tape 150 covers the current collecting body 141, a protective film can be formed on the side of the current collecting member 140 facing the end wall 111, so as to reduce the probability of the corrosion products between the lower plastic 130 and the end wall 111 falling into the electrode assembly 120, and further reduce the risk of short circuit inside the secondary battery 100.

[0071] In order to improve the problem of wrinkles in the adhesion process of the first insulation tape 150 and improve the flatness of the adhesion of the first insulation tape 150, optionally, please refer to Figure 11 and Figure 12 In an example of the secondary battery 100 of the present application, the first adhesive area 151 includes a plurality of cutouts, and the plurality of cutouts divide the first adhesive area 151 into a plurality of adhesive strips 154 connected to each other. In order to facilitate description, the cutout on the first adhesive area 151 is defined as the first cutout 1531. It should be noted that in the present embodiment, the unfolded shape of the first insulation tape 150 is a ring structure, as shown in Figure 12As shown. When the first insulating tape 150 is used for bonding, the second bonding area 152 is first bonded to the current collector body 141, and then the adhesive strip 154 ​​is bent downwards and bonded to the outer peripheral surface of the electrode assembly 120. When the first insulating tape 150 is in the unfolded state, the first cut 1531 can be uniformly arranged along the circumferential direction of the first bonding area 151, that is, multiple adhesive strips 154 are the same size and shape. The first cut 1531 can also be unevenly arranged along the circumferential direction of the first bonding area 151, that is, multiple adhesive strips 154 are different in shape and size. The first cut 1531 can extend along the radial direction of the first insulating tape 150 or along other directions. In order to simplify the processing technology of the first cut 1531 and improve the processing efficiency, optionally, in this embodiment, multiple first cuts 1531 are uniformly arranged along the circumferential direction of the first bonding area 151, and the first cuts 1531 extend along the radial direction of the first insulating tape 150.

[0072] By providing multiple first cuts 1531 in the first bonding area 151, the first bonding area 151 is divided into multiple interconnected adhesive strips 154. The adhesive strips 154 formed in this way can be independently bent and fitted, and during bonding, multiple adhesive overlap areas 155 can be formed on the outer peripheral surface of the electrode assembly 120 (e.g., ...). Figure 11 (As shown in the shaded area), this design reduces the probability of wrinkles forming in the first adhesive area 151 during the bonding process, improving the smoothness of the first insulating tape 150 on the outer peripheral surface of the electrode assembly 120. This design makes the first adhesive area 151 less prone to peeling after immersion in electrolyte, not only improving the insulation effect between the outer peripheral surface of the electrode assembly 120 and the housing 110, but also preventing corrosive substances on the end wall 111 from entering the interior of the electrode assembly 120 through the first adhesive area 151, thereby further reducing the risk of short circuits inside the secondary battery 100.

[0073] Optionally, in one example of the secondary battery 100 of this utility model, please participate... Figure 10 and Figure 13 The second bonding area 152 includes multiple cuts that divide the second bonding area 152 into multiple interconnected adhesive strips 154. For ease of description, the cuts on the second bonding area 152 are defined as second cuts 1532. It should be noted that in this embodiment, the unfolded shape of the first insulating tape 150 is a long strip structure, such as... Figure 13 As shown. When the first insulating tape 150 is used for bonding, the first bonding area 151 is first wound around the circumference of the electrode assembly 120 for bonding, and then the second bonding area 152 is bent toward the surface of the current collector 140 to bond to the surface of the current collector 140. Figure 13As shown, in the first insulating tape 150 is in the unfolded state, the second cut 1532 can be uniformly arranged along the length direction of the second adhesive area 152, that is, the plurality of adhesive strips 154 are the same in size and shape. The second cut 1532 can also be arranged non-uniformly along the length direction of the first insulating tape 150 (as shown in the X-axis direction) Figure 13 ), that is, the plurality of adhesive strips 154 are different in size and shape. The second cut 1532 can extend along the width direction of the first insulating tape 150 (as shown in the Y-axis direction) Figure 13 ), or extend in other directions. In order to simplify the processing process of the second cut 1532 and improve the processing efficiency, the plurality of second cuts 1532 are uniformly arranged along the length direction of the first insulating tape 150, and the second cut 1532 extends along the width direction of the first insulating tape 150 in the embodiment.

[0074] By arranging the plurality of second cuts 1532 on the second adhesive area 152, the second adhesive area 152 is divided into a plurality of interconnected adhesive strips 154. The adhesive strips 154 formed in this way can be independently bent and attached, and can form a plurality of adhesive overlapping areas 155 (as shown in the shadow area in the Figure 10 ) on the outer peripheral surface of the electrode assembly 120 during the adhesion, thereby reducing the probability of wrinkles of the second adhesive area 152 during the adhesion process and improving the flatness of the first insulating tape 150 adhered to the surface of the current collecting member 140. This design makes the second adhesive area 152 not easy to be warped after being soaked in electrolyte, not only can improve the insulation effect between the current collecting member 140 and the end wall 111, but also can prevent the corrosive substances on the end wall 111 from entering the inside of the electrode assembly 120 through the second adhesive area 152, thereby further reducing the risk of short circuit in the secondary battery 100.

[0075] In order to further reduce the risk of corrosive substances generated on the end wall 111 entering the inside of the electrode assembly 120, optionally, please refer to Figure 14 and Figure 15 , in an example of the secondary battery 100 of the utility model, along the thickness direction of the lower plastic 130, the current collecting member 140 is in a solid structure. It should be noted that the current collecting member 140 in a solid structure means that the current collecting member 140 as a whole does not have a hollow structure. This design makes the current collecting member 140 form a complete shielding on the end surface of the electrode assembly 120 towards the end wall 111, thereby further reducing the possibility of corrosive substances generated on the end wall 111 entering the electrode assembly 120 from the end surface of the electrode assembly 120 and entering the inside of the electrode assembly 120, thereby further reducing the risk of short circuit in the secondary battery 100.

[0076] Please refer to Figure 16 and Figure 17In the secondary battery 100 example of the utility model, the secondary battery 100 further includes the second insulating tape 160, the outer peripheral surface of the electrode assembly 120 includes the exposed diaphragm 122 layer, and the winding tail end 171 of the diaphragm layer 170 is fixed by the second insulating tape 160.The diaphragm layer 170 can be wound in the multilayer diaphragm structure of the outer peripheral surface of the electrode assembly 120, and can also be wound in the single-layer diaphragm structure of the outer peripheral surface of the electrode assembly 120, and the specific winding process and end requirement of the electrode assembly 120 are determined.The diaphragm layer 170 is wound in the multilayer diaphragm structure of the outer peripheral surface of the electrode assembly 120 in the embodiment, which can form a larger winding strength on the outer peripheral surface of the electrode assembly 120, and reduce the probability of the electrode assembly 120 being loose.

[0077] The second insulating tape 160 adopts the insulating material resistant to high temperature and electrolyte corrosion, such as polyimide (PI) tape or polytetrafluoroethylene (PTFE) tape or any insulating material capable of meeting the bonding and fixing requirements of the tail end of the diaphragm 122 layer.The bonding area of the second insulating tape 160 can cover the entire winding tail end 171 of the diaphragm layer 170, or can only cover the local area of the length direction of the winding tail end 171 of the diaphragm layer 170.By setting the exposed diaphragm layer 170 on the outer peripheral surface of the electrode assembly 120, it is beneficial for the free electrolyte in the shell 110 to diffuse and absorb through the diaphragm layer 170, so that the free accumulation of electrolyte between the second insulating tape 160 and the side wall 112 of the shell 110 can be reduced, which can reduce the corrosion of electrolyte to the side wall 112 under high temperature conditions, thereby reducing the generation of corrosive substances, and reducing the risk of short circuit in the secondary battery 100.The second insulating tape 160 is in the form of a long strip with a small area in the embodiment, and the size of the second insulating tape 160 is thickness ≤ 50 μm, length ≥ 30 mm, and width ≥ 10 mm in an example, which can further reduce the shielding area of the second insulating tape 160 on the diaphragm layer 170, thereby further reducing the free accumulation of electrolyte between the second insulating tape 160 and the side wall 112 of the shell 110, and further reducing the corrosion degree of electrolyte to the side wall 112, and reducing the risk of short circuit in the secondary battery 100.

[0078] Please refer to Figure 18 The battery pack 200 includes a box body 210 and at least one secondary battery 100 in an embodiment of the utility model, and the box body 210 includes a first box body part 211 and a second box body part 212.The first box body part 211 and the second box body part 212 are overlapped with each other to form a containing space, and a plurality of secondary batteries 100 are accommodated in the containing space, and the plurality of secondary batteries 100 can be connected in series and / or parallel connection.The battery pack 200 can be a battery module, a battery pack, etc.

[0079] Please refer toFigure 19 In an example of the electronic device 300, the electronic device 300 includes a working part 310 and a battery pack 200. The working part 310 is electrically connected to the battery pack 200 to obtain power support. The working part 310 can be a unit component capable of obtaining the power of the battery pack 200 and making corresponding work, such as a fan blade rotating unit, a dust suction working unit of a dust collector, a wheel driving unit in an electric vehicle, and the like. The electronic device 300 can be a vehicle, a mobile phone, a portable device, a notebook computer, a ship, a spacecraft, an electric toy, an electric tool, and the like. The vehicle can be a fuel automobile, a gas automobile, or a new energy automobile, and the new energy automobile can be a pure electric automobile, a hybrid electric automobile, or a range extended automobile, and the like. The spacecraft includes an airplane, a rocket, a space shuttle, a spacecraft, and the like. The electric toy includes a fixed or mobile electric toy, such as a game console, an electric automobile toy, an electric ship toy, an electric airplane toy, and the like. The electric tool includes a metal cutting electric tool, a grinding electric tool, an assembling electric tool, and a railway electric tool, such as an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact electric drill, a concrete vibrator, an electric planer, and the like. The electronic device 300 is not specially limited in the embodiments of the present application. In an example of the electronic device 300, the electronic device 300 is a vehicle, the working part 310 is a vehicle body, and the battery pack 200 is fixedly installed on the vehicle body, thereby providing driving force for the vehicle and realizing the running of the vehicle.

[0080] In the secondary battery, the second part of the lower plastic is provided with a hollow region and a non-hollow region, and the projection area of the hollow region is larger than the projection area of the non-hollow region. This design can form a larger hollow region between the lower plastic and the end wall, increase the discontinuity of the contact area between the two, thereby facilitating the outflow of the electrolyte infiltrated between the lower plastic and the end wall, and reducing the accumulation of the electrolyte between the end wall and the lower plastic. By reducing the accumulation of the electrolyte, the corrosion degree of the electrolyte on the end wall can be effectively reduced, the risk of the corrosion product entering the interior of the electrode assembly can be reduced, and the risk of internal short circuit of the secondary battery can be reduced, thereby improving the safety performance of the secondary battery. Therefore, the present application effectively overcomes some practical problems in the prior art and has high utilization value and use significance. The above embodiments only exemplarily illustrate the principle and effect of the present application, and are not used to limit the present application. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical concept disclosed by the present application should be covered by the claims of the present application.

Claims

1. A secondary battery characterized by comprising: The secondary battery comprises: a shell comprising an end wall; an electrode assembly arranged in the shell; a post installed through the end wall and insulated from the end wall; a lower plastic arranged on a side of the end wall facing the electrode assembly; the lower plastic comprises a first part and a second part, the first part is clamped between the end wall and the post, and the second part is arranged around the outer periphery of the first part; wherein the second part comprises a hollowed-out area and a non-hollowed-out area, and the projection area of the hollowed-out area is greater than the projection area of the non-hollowed-out area along the thickness direction of the lower plastic.

2. The secondary battery according to claim 1, characterized by The hollowed-out area comprises a plurality of hollowed-out units, and the plurality of hollowed-out units are arranged at intervals along the circumferential direction of the second part.

3. The secondary battery according to claim 1, characterized by The second part comprises a body part and a thickened part, and the thickened part is arranged on a side of the body part facing the electrode assembly; the hollowed-out area penetrates through the body part and the thickened part along the thickness direction of the lower plastic.

4. The secondary battery according to claim 3, characterized by The thickness of the thickened part is 0.4-0.8 mm.

5. The secondary battery according to claim 1, characterized by The maximum distance between the lower plastic and the end wall on a side of the end wall facing the electrode assembly is less than the maximum distance between the post and the end wall.

6. The secondary battery according to claim 1, characterized by The thickness of the first part is less than the maximum thickness of the second part.

7. The secondary battery according to any one of claims 1 to 6, characterized by The secondary battery further comprises a current collecting member arranged between the end wall and the electrode assembly and electrically connected to the electrode assembly; a minimum gap h1 is formed between the current collecting member and the lower plastic along the thickness direction of the lower plastic, and 0 8. The secondary battery according to claim 7, characterized by The current collecting member is of a solid structure.

9. The secondary battery according to claim 7, characterized by The current collecting member comprises a current collecting body and a post connecting area, the current collecting body is arranged around the outer periphery of the post connecting area, and the post connecting area is electrically connected to the post; the secondary battery further comprises a first insulating tape, the first insulating tape comprises a first adhesive area and a second adhesive area, the first adhesive area covers the outer peripheral surface of the electrode assembly on a side of the end wall, and the second adhesive area covers the current collecting body; the projection of the part of the post inside the shell along the thickness direction of the lower plastic covers the post connecting area.

10. The secondary battery according to claim 9, characterized by The first adhesive area or the second adhesive area comprises a plurality of cutouts, and the plurality of cutouts divide the first adhesive area or the second adhesive area into a plurality of mutually connected adhesive strips.

11. The secondary battery according to claim 1, characterized by The secondary battery further comprises a second insulating tape, the outer peripheral surface of the electrode assembly comprises a bare separator layer, and the winding tail end of the separator layer is fixed by the second insulating tape.

12. A battery pack, characterized by The secondary battery comprises any one of claims 1-11.

13. An electronic device, comprising: The battery pack comprises claim 12.

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