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 and a current collecting component, the electrode assembly is accommodated in the shell, the electrode assembly comprises a winding structure formed by laminating and winding a positive pole piece, a negative pole piece and a diaphragm, the positive pole piece comprises a positive pole coating area, a positive pole non-coating area and an insulating layer at least covering the junction of the positive pole coating area and the positive pole non-coating area, the positive pole non-coating area extends out of the diaphragm, and the negative pole piece extends out of the diaphragm. Bending towards the winding shaft to form a positive electrode uncoated area stacking area; the current collecting component is welded with the positive electrode uncoated area stacking area; the insulating layer comprises a first insulating layer facing the winding shaft and a second insulating layer deviating from the winding shaft, the first insulating layer and the second insulating layer extend towards the positive electrode uncoated area stacking area, and the height h1 of the first insulating layer is larger than the height h2 of the second insulating layer in the direction of the winding shaft; the technical problem that the positive pole lug collapses and goes wrong in the bending process can be solved.

Description

Technical Field

[0001] The utility model relates to the field of batteries, and in particular to a secondary battery, a battery pack and an electronic device. Background Art

[0002] As one of the core components of new energy vehicles, lithium-ion batteries have the advantages of high energy density, long cycle life, safety and environmental protection, and are gradually becoming the mainstream direction of the electrification era. Lithium-ion batteries are divided into hard-shell batteries, soft-pack batteries, and cylindrical batteries in terms of form. Among them, cylindrical batteries are valued for their high volume energy density, simple structure, easy grouping, and convenience for standardization.

[0003] The battery cell of a cylindrical battery is formed by winding a positive electrode sheet, a separator and a negative electrode sheet. The end of the positive electrode sheet that is not coated with the positive active material is bent toward the center of the cylindrical battery to form a positive electrode uncoated area stacking area, and then the current collecting component is pressed onto the positive electrode uncoated area stacking area for welding and fixing. Generally, the positive electrode sheet is aluminum foil with high hardness. When the current collecting component and the positive electrode uncoated area stacking area are pressed tightly, the positive electrode uncoated area stacking area will collapse and misalign during the bending process. Utility Model Content

[0004] In view of the above shortcomings of the prior art, the utility model provides a secondary battery, a battery pack and an electronic device to improve the technical problem that the stacking area of ​​the positive electrode uncoated area will collapse during the bending process.

[0005] In order to achieve the above-mentioned purpose and other related purposes, the utility model provides a secondary battery, a battery pack and an electronic device, wherein the secondary battery comprises a shell, an electrode assembly and a current collecting member; the electrode assembly is contained in the shell, the electrode assembly comprises a positive electrode sheet, a negative electrode sheet and a winding structure formed by stacking and winding a separator, the positive electrode sheet comprises a positive electrode coating area coated with a positive electrode active material layer and a positive electrode uncoated area not coated with a positive electrode active material layer, and an insulating layer at least covering the junction of the positive electrode coating area and the positive electrode uncoated area, the positive electrode uncoated area along the electrode assembly One end in the direction of the winding axis extends outside the diaphragm and is bent toward the winding axis to form a positive electrode uncoated area stacking area; the current collecting component at least partially covers the positive electrode uncoated area stacking area and is welded to the positive electrode uncoated area stacking area; the insulating layer includes a first insulating layer arranged on the first side surface of the positive electrode sheet facing the winding axis and a second insulating layer on the second side surface away from the winding axis, and the first insulating layer and the second insulating layer both extend toward the positive electrode uncoated area stacking area along the direction of the winding axis, and along the direction of the winding axis, the height h1 of the first insulating layer is greater than the height h2 of the second insulating layer.

[0006] In the above technical scheme, the insulating layer at least covers the junction between the positive electrode coated area and the positive electrode uncoated area, and extends to the bending part of the positive electrode uncoated area stacking area, that is, the insulating layer at least partially covers the positive electrode uncoated area, and can support the pressure from the current collecting component when the positive electrode uncoated area stacking area is bent. Furthermore, the first insulating layer is located on the first side facing the winding axis, that is, below the positive electrode uncoated area stacking area after bending, and can directly provide the positive electrode uncoated area stacking area with a reaction force to resist the pressure from the current collecting component. Setting the height of the first insulating layer to be higher than the height of the second insulating layer can further improve the supporting force for the positive electrode uncoated area stacking area, alleviate the problem of post-collapse of the positive electrode uncoated area stacking area, improve the flatness of the welding plane of the positive electrode uncoated area stacking area, and improve the welding yield.

[0007] In an example of the secondary battery of the present invention, the difference between h1 and h2 is t, and 0.2 mm≤t≤1.5 mm.

[0008] In the above technical solution, the height t of the first insulating layer and the height t of the second insulating layer are in the range of 0.2mm≤t≤1.5mm, so that the first insulating layer maintains a safe distance from the positive electrode uncoated area stacking area, which can reduce the risk of the first insulating layer being crushed and powdered by the positive electrode uncoated area stacking area.

[0009] In an example of the secondary battery of the utility model, the radial dimension of the rear offset part of the outermost circle of the electrode ear toward the outer periphery of the electrode assembly is a, where a≤1.5mm, and the rear offset part is the part between the root of the positive electrode uncoated area and the radial outermost side of the positive electrode uncoated area along the electrode assembly.

[0010] In the above technical scheme, the rear offset part is formed by bending and protruding from the root of the positive electrode uncoated area stacking area toward the radial outside of the electrode assembly during the process of bending the positive electrode uncoated area stacking area toward the winding axis and the compacting after bending. The setting of a≤1.5mm can increase the ring width of the stacking stable area of ​​the positive electrode uncoated area stacking area suitable for welding, which is more conducive to welding, and reduces the slope of the inclined surface formed by the rear offset positive electrode uncoated area stacking area, reduces the gap between the positive electrode uncoated area stacking area and the current collecting component, and improves the reliability and convenience of welding.

[0011] In an example of the secondary battery of the present invention, on the reference plane formed by any radial line of the winding axis and the end face of the electrode assembly, the outer circle of the winding structure cuts n circles of positive electrode uncoated area, and the sum of the thicknesses of the positive electrode sheet, the separator and the negative electrode sheet is b, where a / b<n.

[0012] In the above technical solution, the setting of a / b<n can enable the annular area without pole ears in the winding structure to accommodate the part of the positive electrode uncoated area stacking area located in the outermost circle that is collapsed and misaligned, so that the part of the positive electrode uncoated area stacking area that is misaligned does not exceed the periphery of the electrode assembly, so as to reduce the probability of affecting the electrode assembly into the shell.

[0013] In an example of the secondary battery of the present invention, from the outer circle to the inner circle of the electrode assembly, the positive electrode uncoated area stacking area includes a stacking layer increasing area, a stacking layer stable area and a stacking layer decreasing area in sequence, and the positive electrode uncoated area stacking area located in the stacking layer decreasing area extends in a direction away from the current collecting component.

[0014] In the above technical solution, a concave inclined surface can be formed at the position of the electrode assembly near the winding axis. On the one hand, the inclined surface can play the role of guiding the electrolyte, and on the other hand, it can prevent the stacking area of ​​the positive electrode uncoated area located in the area where the number of stacking layers decreases from warping up, thereby improving the stability and convenience of welding between the current collecting component and the stacking area of ​​the positive electrode uncoated area.

[0015] In an example of the secondary battery of the present invention, the ring width of the stacking area of ​​the positive electrode uncoated area is r, the ring width of the stacking layer stable area is c, and c / r≥0.35.

[0016] In the above technical solution, the setting of c / r≥0.35 can ensure the range of the stable region of the number of stacked layers, improve the reliability of welding, help reduce the internal resistance, and improve the performance of the secondary battery.

[0017] In an example of the secondary battery of the present invention, the insulating layer includes a ceramic filler.

[0018] In the above technical solution, the ceramic filler has a high hardness while ensuring insulation and can provide a relatively stable supporting force.

[0019] In an example of the secondary battery of the present invention, the brightness of the first insulating layer is different from the brightness of the second insulating layer.

[0020] In the above technical solution, by observing the difference in brightness between the first insulating layer and the second insulating layer, the front and back sides of the positive electrode sheet can be effectively distinguished to prevent the situation where the front and back sides of the positive electrode sheet are placed upside down; and the insulating layer does not participate in the chemical reaction, and the front and back sides of the positive electrode sheet can be identified through the insulating layer without the need for additional markings, which has little impact on the battery.

[0021] The utility model also provides a battery pack, which comprises any one of the above-mentioned secondary batteries.

[0022] The utility model also provides an electronic device, which comprises the battery pack mentioned above.

[0023] In the secondary battery of the utility model, the insulating layer at least covers the junction between the positive electrode coated area and the positive electrode uncoated area, and extends to the bending part of the positive electrode uncoated area stacking area, that is, the insulating layer at least partially covers the unbending area of ​​the positive electrode uncoated area, and can support the force from the compression of the current collecting component when the positive electrode uncoated area stacking area is bent. Furthermore, the first insulating layer is located on the first side facing the winding axis, that is, located below the positive electrode uncoated area stacking area after bending, and can directly provide the positive electrode uncoated area stacking area with a reaction force to resist the pressure from the current collecting component. The height of the first insulating layer is set to be higher than the height of the second insulating layer, which can further improve the support force for the positive electrode uncoated area stacking area, alleviate the problem of post-collapse of the positive electrode uncoated area stacking area, improve the flatness of the welding plane of the positive electrode uncoated area stacking area, and improve the welding yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the utility model. For ordinary technicians in this field, other embodiments can be obtained based on these drawings without paying creative work.

[0025] Figure 1 This is a schematic structural diagram of an embodiment of a secondary battery of the utility model;

[0026] Figure 2 This is a schematic diagram of the structure of an electrode assembly in an embodiment of a secondary battery of the utility model;

[0027] Figure 3 A cross-sectional view of an electrode assembly in an embodiment of a secondary battery of the present utility model;

[0028] Figure 4 A cross-sectional view of a single positive electrode sheet in an embodiment of a secondary battery of the utility model;

[0029] Figure 5 This is a schematic structural diagram of the stacking area of ​​the positive electrode uncoated area in one embodiment of the secondary battery of the utility model;

[0030] Figure 6 A schematic diagram of an embodiment of a battery pack of the utility model;

[0031] Figure 7 It is a schematic diagram of an embodiment of the electronic device of the present invention.

[0032] Component number description

[0033] 1. electronic device; 10. battery pack; 11. working part; 101. box; 102. box cover; 100. secondary battery; 110. shell; 111. end wall; 112. side wall; 113. opening; 120. electrode assembly; 121. positive electrode sheet; 1211. positive electrode current collector; 1212. positive electrode coating area; 1213. positive electrode uncoated area; 1214. first side; 1215. second side; 122. separator; 123. negative electrode sheet; 1231. negative electrode current collector; 1232. Negative electrode coating area; 1233, negative electrode uncoated area; 124, negative electrode uncoated area stacking area; 125, positive electrode uncoated area stacking area; 1251, stacking layer number increasing area; 1252, stacking layer number stable area; 1253, stacking layer number decreasing area; 126, bending portion; 127, winding axis; 128, insulating layer; 1281, first insulating layer; 1282, second insulating layer; 130, current collecting component; 131, first current collecting component; 132, second current collecting component; 150, pole; 160, cover plate. DETAILED DESCRIPTION

[0034] The following describes the implementation of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments 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 invention are intended to describe specific implementation schemes, rather than to limit the scope of protection of the present invention. The test methods for which specific conditions are not specified in the following examples are usually carried out under conventional conditions or under the conditions recommended by the manufacturers.

[0035] When numerical ranges are given in the embodiments, it should be understood that unless otherwise specified in the present invention, both endpoints of each numerical range and any value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention are in accordance with the prior art mastery of those skilled in the art and the description of the present invention, and any method, device and material of the prior art similar or equivalent to the method, device and material in the embodiments of the present invention can also be used to implement the present invention.

[0036] It should be noted that the terms such as "upper", "lower", "left", "right", "middle" and "one" cited in this specification are only for the convenience of description and are not used to limit the scope of implementation of the present utility model. Changes or adjustments to their relative relationships should be regarded as the scope of implementation of the present utility model without substantially changing the technical content.

[0037] The secondary battery includes a housing and an electrode assembly. The electrode assembly is contained in the housing. The electrode assembly is a component in the secondary battery where electrochemical reactions occur. The housing may contain one or more electrode assemblies.

[0038] The electrode assembly is mainly formed by winding or stacking the positive electrode sheet and the negative electrode sheet, and a separator is usually provided between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet includes a positive electrode collector and a positive electrode active material, and the positive electrode active material is coated on the surface of the positive electrode collector; the positive electrode collector includes a positive electrode coating area coated with an active material and a positive electrode uncoated area not coated with an active material, and the positive electrode uncoated area is wound to form a positive electrode uncoated area stacking area of ​​the electrode assembly. The negative electrode sheet includes a negative electrode collector and a negative electrode active material, and the negative electrode active material is coated on the surface of the negative electrode collector; the negative electrode collector includes a negative electrode coating area coated with an active material and a negative electrode uncoated area not coated with an active material, and the uncoated area is wound to form a negative electrode uncoated area stacking area of ​​the electrode assembly. Taking a lithium-ion secondary battery as an example, the material of the positive electrode collector can be aluminum, and the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganese oxide, etc. The negative electrode current collector may be made of copper, and the negative electrode active material layer includes a negative electrode active material, which may be carbon or silicon. The separator may be made of PP (polypropylene) or PE (polyethylene). In order to protect and insulate the battery cell, an insulating film may be coated on the outside of the battery cell, and the insulating film may be synthesized from PP, PE, PET, PVC or other high molecular polymer materials.

[0039] However, the inventor of the utility model discovered that in existing secondary batteries, the positive electrode plates are generally made of aluminum foil, which has a relatively high hardness. When the current collecting component and the positive electrode uncoated area stacking area are pressed tightly, the positive electrode uncoated area stacking area will collapse and misalign during the bending process. This will cause the flatness of the welding plane of the entire positive electrode uncoated area stacking area, resulting in a large gap between the current collecting component and the positive electrode uncoated area stacking area, affecting the reliability of welding between the current collecting component and the positive electrode uncoated area stacking area.

[0040] In view of this, the utility model provides a technical solution, in which an insulating layer is arranged below the positive electrode uncoated area stacking area, and the insulating layer includes a first insulating layer arranged on the first side surface of the positive electrode sheet facing the winding axis and a second insulating layer located on the second side surface opposite to the first side surface. The height of the first insulating layer is set to be higher than the height of the second insulating layer, which can further improve the supporting force of the positive electrode uncoated area stacking area, alleviate the problem of collapse and error of the positive electrode uncoated area stacking area, improve the flatness of the welding plane of the positive electrode uncoated area stacking area, and improve the welding yield.

[0041] See also Figures 1 to 7 The utility model provides a secondary battery 100 , which includes a shell 110 , an electrode assembly 120 , a current collecting member 130 , an insulating layer 128 , a pole 150 and a cap plate 160 .

[0042] See also Figure 1 The shell 110 includes an end wall 111 and a side wall 112 surrounding the end wall 111. As long as a stable sealing and electrical connection relationship can be formed, the connection between the end wall 111 and the side wall 112 can be achieved in a variety of ways, such as integral stamping, integral casting or split welding. The surrounding of the side wall 112 is not limited, and can be cylindrical or prismatic, or can be surrounded along any other closed loop contour that can match the end wall 111. As an embodiment, the outer edge of the end wall 111 in this embodiment is circular, and the side wall 112 is cylindrical and surrounds the outer edge of the end wall 111, and a circular opening 113 is formed at one end of the side wall 112 away from the end wall 111. A housing cavity is formed in the shell 110 surrounded by the end wall 111 and the side wall 112, which is used to accommodate the electrode assembly 120, the electrolyte and other necessary battery components. 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 may be made of a variety of materials, such as copper, iron, aluminum, steel, aluminum alloy, etc. In order to prevent the shell 110 from rusting during long-term use, a layer of rust-proof material such as metal nickel may be plated on the surface of the shell 110.

[0043] See also Figures 1 to 3The electrode assembly 120 is accommodated in the shell 110. The electrode assembly 120 includes a positive electrode sheet 121, a negative electrode sheet 123 and a winding structure formed by stacking and winding a separator 122. The positive electrode sheet 121 includes a positive electrode collector 1211 and a positive electrode active material. The positive electrode active material is coated on the surface of the positive electrode collector 1211; the positive electrode collector 1211 includes a positive electrode coating area 1212 coated with an active material and a positive electrode uncoated area 1213 not coated with the active material, and an insulating layer 128 covering at least the junction of the positive electrode coating area 1212 and the positive electrode uncoated area 1213; the positive electrode uncoated area 1213 is along the winding axis of the electrode assembly 120. One end in the direction of 127 extends to the outside of the diaphragm 122, and is bent in the direction of the winding axis 127 to form a stacked positive uncoated area stacking area 125; the negative electrode sheet 123 includes a negative electrode collector 1231 and a negative electrode active material, and the negative electrode active material is coated on the surface of the negative electrode collector 1231; the negative electrode collector 1231 includes a negative electrode coated area 1232 coated with an active material and a negative electrode uncoated area 1233 not coated with the active material, and the negative electrode uncoated area 1233 extends to the outside of the diaphragm 122 along one end in the direction of the winding axis 127 of the electrode assembly 120, and is bent in the direction of the winding axis 127 to form a stacked negative electrode uncoated area stacking area 124.

[0044] See also Figure 1 The current collecting member 130 includes a first current collecting member 131 and a second current collecting member 132. The materials of the first current collecting member 131 and the second current collecting member 132 are selected according to the polarity of the tabs connected thereto. For example, if the second current collecting member 132 is connected to the positive electrode uncoated area stacking area 125, the second current collecting member 132 can be made of aluminum metal. At this time, the first current collecting member 131 is connected to the negative electrode uncoated area stacking area 124, and the material can be selected from copper metal. If the second current collecting member 132 is connected to the negative electrode uncoated area stacking area 124, the second current collecting member 132 can be made of copper metal. At this time, the first current collecting member 131 is connected to the positive electrode uncoated area stacking area 125, and the material of the first current collecting member 131 can be selected from aluminum metal. The shapes and structures of the second current collecting component 132 and the first current collecting component 131 are also not limited, and are suitable for achieving a stable and reliable electrical connection relationship. In this embodiment, the first current collecting component 131 at least partially covers the positive electrode uncoated area stacking area 125 and is welded to the positive electrode uncoated area stacking area 125. The second current collecting component 132 at least partially covers the negative electrode uncoated area stacking area 124 and is welded to the negative electrode uncoated area stacking area 124. The first current collecting component 131 is made of aluminum metal.

[0045] See also Figure 4The insulating layer 128 at least covers the junction of the positive electrode coating area 1212 and the positive electrode uncoated area 1213, and extends to the bending portion 126 of the positive electrode uncoated area stacking area 125, that is, the insulating layer 128 can partially overlap with the positive electrode coating area 1212, and can also be arranged in contact with the positive electrode coating area 1212. During actual processing, the bending portion 126 of the positive electrode uncoated area stacking area 125 is a bending fillet, and the insulating layer 128 at least partially covers the positive electrode uncoated area 1213, which can support the pressing force from the current collecting component 130 when the positive electrode uncoated area stacking area 125 is bent. The above two forms of insulating layer 128 can at least partially cover the positive electrode uncoated area 1213, and can support the pressing force from the current collecting component 130 when the positive electrode uncoated area stacking area 125 is bent. Preferably, in this embodiment, the insulating layer 128 partially overlaps with the positive electrode coating area 1212, and this setting has a better supporting effect.

[0046] See also Figure 3 and Figure 4 The insulating layer 128 includes a first insulating layer 1281 arranged on a first side surface 1214 of the positive electrode sheet 121 facing the winding axis 127 and a second insulating layer 1282 on a second side surface 1215 away from the winding axis 127. Both the first insulating layer 1281 and the second insulating layer 1282 extend toward the positive electrode uncoated area stacking area 125 along the direction of the winding axis 127, that is, the first insulating layer 1281 is located below the positive electrode uncoated area stacking area 125 after bending, and can directly provide the positive electrode uncoated area stacking area 125 with a reaction force to resist the pressure from the current collecting member 130; further, along the direction of the winding axis 127, the height h1 of the first insulating layer 1281 is greater than the height h2 of the second insulating layer 1282. This arrangement can further improve the support force for the positive electrode uncoated area stacking area 125, alleviate the problem of collapse and displacement of the positive electrode uncoated area stacking area 125, improve the flatness of the welding plane of the positive electrode uncoated area stacking area 125, and improve the welding yield.

[0047] See also Figure 1The pole 150 passes through the end wall 111 and is insulated from the end wall 111 . The structure of the pole 150 can be in any suitable form that can pass through the end wall 111 to be electrically connected to the positive electrode sheet 121 or the negative electrode sheet 123. For example, the cross-section can be circular, square, prismatic or a special-shaped contour that can achieve stable conductivity. The end of the pole 150 facing the electrode assembly 120 passes through the end wall 111 to be directly electrically connected to the pole ear or is electrically connected through an indirect transfer. For example, the pole 150 can be electrically connected to the positive electrode sheet 121 through the first current collecting member 131, or it can be electrically connected to the negative electrode sheet 123 through the second current collecting member 132. The end of the pole 150 facing away from the electrode assembly 120 is exposed to the outside of the shell 110 to form a corresponding electrode. The electrical property of the pole 150 can be positive or negative. For example, in one embodiment, the pole 150 is electrically connected to the positive electrode uncoated area stacking area 125, then the pole 150 is the positive electrode, and the shell 110 forms the corresponding negative electrode. In another embodiment, the pole 150 is electrically connected to the negative electrode uncoated area stacking area 124, then the pole 150 is a negative electrode, and the shell 110 forms a corresponding positive electrode. The end wall 111 is provided with a pole 150 mounting hole, and the pole 150 is sealed and insulated and installed in the pole 150 mounting hole. This shell 110 structure can improve the installation efficiency, and the assembly performance and sealing performance are better than the shell 110 form with openings 113 at both ends.

[0048] See also Figure 1 , the pole 150 is made of a conductive metal material. The material of the pole 150 may be aluminum. If the material of the pole 150 is aluminum, the riveting process can be easily performed. In this embodiment, the pole 150 is made of aluminum, and the polarity is positive. Corresponding to the pole 150, the shell 110 is made of low-carbon steel, and a negative pole is formed correspondingly, and the pole 150 is electrically insulated from the shell 110. Electrical insulation between the pole 150 and the end wall 111 of the shell 110 can be achieved in various ways. For example, insulation can be achieved by placing an insulating gasket between the pole 150 and the end wall 111. Alternatively, insulation can be achieved by forming an insulating coating layer on a portion of the pole 150. Alternatively, some of the above methods may be applied in combination.

[0049] See also Figure 1, the cover plate 160 is sealed and installed on the opening 113; the outer edge shape of the cover plate 160 corresponds to the shape of the opening 113, and is connected to the side wall 112 to seal the opening 113. In a specific embodiment, the periphery of the cover plate 160 is provided with a convex portion protruding toward the inside of the shell 110, and the side of the convex portion away from the electrode assembly 120 is formed as a first recess, and the positive projection shape of the first recess is not limited, and can be a ring, square or other irregular shapes, etc. The convex portion includes a first side wall 112 that cooperates with the inner wall of the shell 110, and the first side wall 112 cooperates with the side wall 112 close to the opening 113. The convex portion is used for the assembly guide of the cover plate 160 and the opening 113, and the cooperation between the side wall 112 of the shell 110 and the cover plate 160 can enable the cover plate 160 and the opening 113 to be quickly positioned along the circumferential direction, thereby improving the welding efficiency and the radial position accuracy of the welding.

[0050] See also Figure 4 In an example of the secondary battery 100 of the present invention, the difference between h1 and h2 is t, 0.2mm≤t≤1.5mm, for example, it can be 0.2mm, 0.4mm, 0.5mm, 0.6mm, 0.8mm, 1.0mm, 1.2mm or 1.5mm, etc. This setting allows the first insulating layer 1281 to maintain a safe distance from the positive electrode uncoated area stacking area 125, which can reduce the risk of the first insulating layer 1281 being crushed and powdered by the positive electrode uncoated area stacking area 125.

[0051] See also Figure 5 In an example of the secondary battery 100 of the present invention, the radial dimension of the rear offset portion of the outermost ring of the pole ear toward the outer periphery of the electrode assembly 120 is a, a≤1.5mm, for example, a can be 0.1mm, 0.2mm, 0.4mm, 0.5mm, 0.6mm, 0.8mm, 1.0mm, 1.2mm or 1.5mm, etc., and the rear offset portion is the portion between the root of the positive electrode uncoated area 1213 and the radial outermost side of the positive electrode uncoated area 1213 along the electrode assembly 120. The rear offset part is formed by bending and protruding from the root of the positive electrode uncoated area stacking area 125 toward the radial outside of the electrode assembly 120 during the bending process of the positive electrode uncoated area stacking area 125 toward the winding axis 127 and the bending and compacting process. The setting of a≤1.5mm can increase the ring width of the stacking stable area of ​​the positive electrode uncoated area stacking area 125 suitable for welding, which is more conducive to welding, and reduces the slope of the inclined surface formed by the rear offset positive electrode uncoated area stacking area 125, reduces the gap between the positive electrode uncoated area stacking area 125 and the current collecting component 130, and can improve the reliability and convenience of welding.

[0052] See also Figure 2 and Figure 5In an example of the secondary battery 100 of the present invention, on the reference plane formed by any radial line of the winding shaft 127 and the end surface of the electrode assembly 120, the outer ring of the winding structure cuts n circles of positive electrode uncoated area 1213, n can be any value, which is not limited to this, the sum of the thickness of the positive electrode sheet 121, the separator 122 and the negative electrode sheet 123 is b, further, a / b<n, a is the radial dimension of the offset part of the electrode ear toward the outer periphery of the electrode assembly 120, and b is a single circle of the positive electrode sheet 121, the separator 122 and the negative electrode sheet 123 The thickness of the element, the value of b is not limited and depends on the actual situation. a / b is used to characterize the number of a unit of the positive electrode plate 121, the diaphragm 122 and the negative electrode plate 123 that are partially covered by the tab toward the periphery of the electrode assembly 120. This setting can enable the annular area without tabs in the winding structure to accommodate the collapsed and offset part of the positive electrode uncoated area stacking area 125 located in the outermost circle, so that the offset part of the positive electrode uncoated area stacking area 125 does not exceed the periphery of the electrode assembly 120, so as to reduce the probability of affecting the entry of the electrode assembly 120 into the shell.

[0053] See also Figure 5 In an example of the secondary battery 100 of the present invention, from the outer circle to the inner circle of the electrode assembly 120, the positive electrode uncoated area stacking area 125 includes a stacking layer increasing area 1251, a stacking layer stabilizing area 1252 and a stacking layer decreasing area 1253 in sequence. The positive electrode uncoated area stacking area 125 located in the stacking layer decreasing area 1253 extends in a direction away from the current collecting member 130. This arrangement can form a concave inclined surface at a position of the electrode assembly 120 close to the winding axis 127. On the one hand, the inclined surface can play a role in guiding the electrolyte, and on the other hand, it can prevent the positive electrode uncoated area stacking area 125 located in the stacking layer decreasing area 1253 from warping up, thereby improving the stability and convenience of welding the first current collecting member 131 and the positive electrode uncoated area stacking area 125.

[0054] See also Figure 5 In an example of the secondary battery 100 of the present invention, the ring width of the positive electrode uncoated area stacking zone 125 is r, the ring width of the stacking layer number stable zone 1252 is c, c / r ≥ 0.35, for example, it can be 0.35, 0.4, 0.45, 0.5, 0.6, 0.7 or 0.8, etc., c / r within this range can ensure the range of the stacking layer number stable zone 1252, improve the reliability of welding, help reduce the internal resistance, and improve the performance of the secondary battery 100.

[0055] See also Figure 4In an example of the secondary battery 100 of the utility model, the insulating layer 128 includes a ceramic filler. The ceramic filler includes at least one of aluminum oxide, boehmite, titanium dioxide, zirconium dioxide, zinc oxide, barium sulfate, boron nitride, aluminum nitride, and magnesium nitride. However, the present application is not limited to these materials, and other ceramic fillers used as the pole piece insulating layer 128 can also be used. The ceramic filler in the present application can be selected from any one of the materials listed above, or any combination of the materials listed above. The ceramic filler has a high hardness while ensuring insulation, and can provide a more stable supporting force.

[0056] See also Figure 4 In an example of the secondary battery 100 of the present invention, the brightness of the first insulating layer 1281 is different from the brightness of the second insulating layer 1282, and the difference in brightness can be obtained by adding different color developers or different proportions of the same color developer to the first insulating layer 1281 or the second insulating layer 1282. The color developer includes but is not limited to at least one of titanium chrome brown, titanium nickel yellow, bismuth vanadate, chromium oxide green, cobalt green, cobalt blue, iron blue, cadmium red, cadmium yellow, lithopone, carbon black, iron oxide red, and iron oxide yellow, that is, the color developer can be any one of the materials listed above, or a combination of any two or more of the materials listed above. By observing the difference in brightness between the first insulating layer 1281 and the second insulating layer 1282, the front and back sides of the positive electrode sheet 121 can be effectively distinguished to prevent the positive electrode sheet 121 from being placed upside down. In addition, the insulating layer 128 does not participate in the chemical reaction. The front and back sides of the positive electrode sheet 121 can be identified through the insulating layer 128 without the need for additional markings, which has little impact on the battery.

[0057] See also Figure 6 The utility model also provides a battery pack 10, the battery pack 10 includes any of the above-mentioned secondary batteries 100. In one embodiment of the battery pack 10 of the utility model, the battery pack 10 includes a box body 101, a box cover 102 and a plurality of secondary batteries 100. The plurality of secondary batteries 100 are placed in the box body 101, connected in series or in parallel, or in a mixture of series and parallel. The box cover 102 is sealed on the box body 101 to protect the plurality of secondary batteries 100. It should be noted that, in addition to the secondary battery 100 of the utility model, the battery pack 10 may also include a battery pack 10 thermal management system, a circuit board and other parts. The battery pack 10 may be a battery module, a battery pack, an energy storage cabinet, etc.; they will not be described one by one here.

[0058] See also Figure 7The utility model also provides an electronic device 1, which includes the above-mentioned battery pack 10. The working part 11 is electrically connected to the battery pack 10 to obtain power support. As an example, the electronic device 1 is a vehicle, and the vehicle can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc., but is not limited to this. The working part 11 is a vehicle body, and the battery pack 10 is arranged at the bottom of the vehicle body, and provides power support for the driving of the vehicle or the operation of electrical components in the vehicle. However, in some other embodiments, the electronic device 1 can also be a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy and an electric tool, etc. Spacecraft include airplanes, rockets, space shuttles and spacecrafts, etc.; the working part 11 can be a unit component that can obtain the power of the battery pack 10 and perform corresponding work, such as a fan blade rotation unit, a vacuum cleaner dust removal unit, etc. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. The present application embodiment does not impose any special restrictions on the above-mentioned electronic device 1.

[0059] In the utility model secondary battery, the insulating layer at least covers the junction of the positive electrode coating area and the positive electrode uncoated area, and extends to the bending part of the positive electrode uncoated area stacking area, that is, the insulating layer at least partially covers the positive electrode uncoated area, and can support the force from the current collecting component when the positive electrode uncoated area stacking area is bent. Further, the first insulating layer is located on the first side facing the winding axis, that is, located below the positive electrode uncoated area stacking area after bending, and can directly provide the positive electrode uncoated area stacking area with a reaction force to resist the pressure from the current collecting component. The height of the first insulating layer is set to be higher than the height of the second insulating layer, which can further improve the support force of the positive electrode uncoated area stacking area, alleviate the problem of collapse and misalignment of the positive electrode uncoated area stacking area, improve the flatness of the welding plane of the positive electrode uncoated area stacking area, and improve the welding yield. Therefore, the utility model effectively overcomes some practical problems in the prior art and has a high utilization value and use significance. The above embodiments only illustrate the principle and efficacy of the utility model, and are not used to limit the utility model. Anyone familiar with the technology can modify or change the above embodiments without violating the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the relevant technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A secondary battery, characterized in that: include: case; An electrode assembly, contained in the shell, the electrode assembly comprising a positive electrode sheet, a negative electrode sheet and a winding structure formed by stacking and winding a separator, the positive electrode sheet comprising a positive electrode coating area coated with a positive electrode active material layer and a positive electrode uncoated area not coated with a positive electrode active material layer, and an insulating layer covering at least a junction between the positive electrode coating area and the positive electrode uncoated area, one end of the positive electrode uncoated area along the winding axis direction of the electrode assembly extends to the outside of the separator, and is bent toward the winding axis to form a positive electrode uncoated area stacking area; a current collecting member, at least partially covering the positive electrode uncoated region stacking region and being welded to the positive electrode uncoated region stacking region; Among them, the insulating layer includes a first insulating layer arranged on the first side of the positive electrode sheet facing the winding axis and a second insulating layer on the second side away from the winding axis, and the first insulating layer and the second insulating layer both extend along the direction of the winding axis toward the positive electrode uncoated area stacking area, and along the direction of the winding axis, the height h1 of the first insulating layer is greater than the height h2 of the second insulating layer.

2. The secondary battery according to claim 1, characterized in that: The difference between h1 and h2 is t, 0.2 mm ≤ t ≤ 1.5 mm.

3. The secondary battery according to claim 1, characterized in that: The radial dimension of the rear offset part of the positive uncoated area stacking area located in the outermost circle toward the outer periphery of the electrode assembly is a, where a≤1.5mm, and the rear offset part is the part between the root of the positive uncoated area and the radial outermost side of the positive uncoated area along the electrode assembly.

4. The secondary battery according to claim 3, characterized in that: On the reference plane formed by any radial line of the winding axis and the end face of the electrode assembly, the outer circle of the winding structure cuts n circles of the positive electrode uncoated area, and the sum of the thicknesses of the positive electrode sheet, the separator and the negative electrode sheet is b, where a / b<n.

5. The secondary battery according to claim 1, characterized in that: From the outer circle to the inner circle of the electrode assembly, the positive electrode uncoated area stacking area includes a stacking layer increasing area, a stacking layer stabilizing area and a stacking layer decreasing area in sequence, and the positive electrode uncoated area stacking area located in the stacking layer decreasing area extends in a direction away from the current collecting component.

6. The secondary battery according to claim 5, characterized in that: The ring width of the stacking area of ​​the positive electrode uncoated area is r, and the ring width of the stacking layer number stable area is c, and c / r≥0.

35.

7. The secondary battery according to claim 1, characterized in that: The insulating layer includes a ceramic filler.

8. The secondary battery according to claim 7, characterized in that: The brightness of the first insulating layer is different from the brightness of the second insulating layer.

9. A battery pack, characterized in that: A secondary battery comprising the secondary battery according to any one of claims 1 to 8.

10. An electronic device, characterized in that: A battery pack comprising the battery pack of claim 9.

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