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, an insulating layer 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 first pole piece, a second pole piece and a diaphragm, and a first end of the electrode assembly comprises a first tab which extends out of the diaphragm in the axial direction of the electrode assembly and is bent; the insulating layer comprises a first coating layer and a second coating layer which are integrally formed, the first coating layer coats the end surface of the first end of the electrode assembly, and the second coating layer extends from the outer periphery of the first coating layer along the axial direction of the electrode assembly and coats the outer peripheral surface of the electrode assembly; the first coating layer is arranged around the current collecting component or at least partially located between the current collecting component and the electrode assembly, and the technical problem that metal dendrites are generated on the negative electrode side diaphragm due to the fact that electrolyte directly flows to the outermost ring of the electrode assembly from a gap between the current collecting component and the insulation paste can be solved.

Description

Technical Field

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

[0002] Currently, large cylindrical batteries are increasingly favored by major automakers due to their high safety, long life, excellent fast charging performance, good battery consistency and low production cost.

[0003] After the current collecting component of the large cylindrical battery is welded to the positive end of the electrode assembly, an insulating layer is coated on the periphery of the electrode assembly to isolate the positive electrode tab and the shell. The insulating layer usually also covers the periphery of the current collecting component. However, due to the hollow structure on the current collecting component, the electrolyte will flow directly from the gap between the current collecting component and the insulating layer to the outermost circle of the electrode assembly, causing the metal ions to be reduced on the negative electrode side diaphragm and generate metal dendrites, which then pierce the diaphragm and cause an internal short circuit in the electrode assembly. Utility Model Content

[0004] The utility model provides a secondary battery, a battery pack and an electronic device to improve the technical problem that electrolyte flows directly from the gap between the current collecting component and the insulating glue to the outermost circle of the electrode assembly, resulting in the generation of metal dendrites on the negative electrode side diaphragm.

[0005] To achieve the above-mentioned objectives and other related objectives, the present invention provides a secondary battery, a battery pack and an electronic device, wherein the secondary battery includes a shell, an electrode assembly, an insulating layer and a current collecting component; the electrode assembly is accommodated in the shell, and the electrode assembly includes a first electrode sheet, a second electrode sheet and a winding structure formed by stacking and winding a diaphragm, and the first end of the electrode assembly includes a first electrode ear formed by extending the diaphragm along the axial direction of the electrode assembly and bending; the insulating layer includes an integrally formed first covering layer and a second covering layer to isolate the first electrode ear from the shell, the first covering layer covers the end face of the first end of the electrode assembly, and the second covering layer extends from the outer peripheral edge of the first covering layer along the axial direction of the electrode assembly and covers the outer peripheral surface of the electrode assembly; the current collecting component is welded to the first electrode ear; the first covering layer is arranged around the current collecting component or is at least partially located between the current collecting component and the electrode assembly.

[0006] In the above technical solution, the first covering layer is coated on the end face of the first end of the electrode assembly, and there is no barrier of the current collecting component, so that the first covering layer and the end face of the first end fit more closely. In particular, when the first covering layer is at least partially located between the current collecting component and the electrode assembly, the current collecting component also has a compression effect on the first covering layer, which can further improve the adhesion of the first covering layer to the end face of the first end. In addition, the second covering layer extends from the outer peripheral edge of the first covering layer along the axial direction of the electrode assembly and is coated on the outer peripheral surface of the electrode assembly. Therefore, the fixing force of the insulating layer on the outside of the electrode assembly is significantly improved, reducing the probability of the electrolyte flowing directly from the gap between the current collecting component and the insulating glue to the outermost circle of the electrode assembly, and alleviating the technical problem of generating metal dendrites on the negative electrode side diaphragm.

[0007] In an example of the secondary battery of the present invention, the first coating layer is ring-shaped.

[0008] In the above technical solution, directly configuring the first coating layer in a ring shape that matches the electrode assembly improves the flatness of the insulating tape on the first end surface, thereby preventing wrinkles on the first end surface. This allows the first coating layer to fit more closely to the first end surface, further enhancing the insulating layer's securing force on the outer side of the electrode assembly. Furthermore, this reduces the risk of liquid accumulation between the insulating layer and the electrode assembly, alleviating the problem of the first coating layer being easily debonded due to liquid accumulation, thereby reducing the risk of electrolyte flowing directly from between the insulating layer and the electrode assembly to the outermost ring of the electrode assembly.

[0009] In an example of the secondary battery of the present invention, the second covering layer includes n sub-patches, where n≥2, and the n sub-patches are connected to the outer periphery of the first covering layer and distributed along the circumference of the first covering layer.

[0010] In the above technical solution, n sub-patches are connected to the outer periphery of the first covering layer. After the first covering layer is first adhered to the end face of the first end, the n sub-patches are then covered on the outer side of the side wall along the axial direction of the shell away from the first covering layer. This arrangement can reduce the possibility of wrinkles on the side wall of the second covering layer, making the appearance of the electrode assembly more beautiful and also facilitating insertion into the shell.

[0011] In an example of the secondary battery of the present invention, when the insulating layer is expanded, the inner peripheries of each adjacent sub-patch are connected, and along the radial direction of the first covering layer, the arc length on each sub-patch is equal everywhere, the arc length of each sub-patch is Li, the diameter of the outer periphery of the first covering layer is d, L1=L2=…=Li, and Li×n=πd.

[0012] In the above technical solution, the arc length on each sub-patch is set to be equal everywhere, that is, the arc length at the connection between each sub-patch and the first coating layer is equal to the arc length of the outer periphery of the sub-patch, and the two opposite radial sides are parallel. When n sub-patches are coated on the side wall, the outer peripheries of all sub-patches can be just connected and equal to the circumference of the side wall, so as to achieve no gaps and no overlaps between each sub-patch. This setting is both beautiful and can achieve better coating and fixing effects.

[0013] In an example of the secondary battery of the present invention, the first covering layer at least covers the outermost circle of the first electrode tab.

[0014] In the above technical solution, this setting can limit and fix the first pole ear in the outermost circle, which can not only prevent the first pole ear from connecting with the shell and causing a short circuit, but also reduce the risk of the first pole ear in the outermost circle breaking and falling into the battery to cause a short circuit.

[0015] In an example of the secondary battery of the present invention, the current collecting component and the first tab are welded to form a weld mark, the inner periphery of the first covering layer is located outside the weld mark, and the shortest distance from the inner periphery of the first covering layer to the weld mark is a, a≥2mm.

[0016] In the above technical solution, the insulating layer is first pasted to the electrode assembly, and then the welding process of the current collecting component and the first electrode ear is carried out. This setting enables the first coating layer to avoid the weld mark to reduce the risk of thermal impact. Preferably, the limitation of a≥2mm can keep the first coating layer and the weld mark at a safe welding distance.

[0017] In an example of the secondary battery of the present invention, the first coating layer includes an overlapping portion overlapping with the current collecting member, the overlapping portion is annular, and the ring width of the overlapping portion is b, 0mm<b≤5mm.

[0018] In the above technical solution, the first cladding layer is placed between the current collecting member and the first tab, eliminating the barrier of the current collecting member. This allows the first cladding layer to fit more closely with the end face of the first terminal. Furthermore, the first cladding layer includes an overlapping portion that overlaps with the current collecting member, which provides a compressive effect on the first cladding layer, further improving the adhesion of the first cladding layer to the end face of the first terminal and reducing the risk of debonding of the insulating layer. The setting of 0mm<b≤5mm ensures overlap between the insulating layer and the current collecting member while maintaining a safe welding distance between the first cladding layer and the weld mark.

[0019] In an example of the secondary battery of the present invention, the ring width of the first covering layer is c, 0.5mm≤c≤22.5mm, and the current collecting member and the first electrode tab are welded to form a weld mark, which is projected toward the first end along the axial direction of the electrode assembly. When the first covering layer and the weld mark have an overlapping area, a weld mark avoidance area corresponding to the weld mark is provided on the first covering layer.

[0020] In the above technical solution, the setting of c≥0.5mm can achieve a first coating layer with a width of at least 0.5mm, so as to achieve isolation of the first electrode ear and the shell, and block the electrolyte from flowing directly into the outermost side of the electrode assembly. c≤22.5mm limits the maximum ring width of the first coating layer. This range is limited by the radius of the electrode assembly. The first coating layer within this range can obtain better insulation and electrolyte blocking effects. The setting of the weld mark avoidance zone can achieve that the first coating layer can avoid the weld marks of the current collecting component and the first electrode ear, reducing the risk of the first coating layer being affected by heat during welding.

[0021] In an example of the secondary battery of the present invention, along the axial direction of the electrode assembly, the height of the second coating layer is e, 0.1 mm < e ≤ 120 mm.

[0022] In the above technical solution, the setting of e > 0.1 mm allows the second coating layer to have a height of at least 0.1 mm, thereby isolating the outer periphery of the first end of the electrode assembly from contact with the housing and enhancing the securing force of the insulating layer to the first end of the electrode assembly. The maximum height of the second coating layer is defined by e ≤ 120 mm, which is limited by the height of the electrode assembly. Within this range, the second coating layer can effectively secure the outer periphery of the electrode assembly.

[0023] The utility model also provides a battery pack, which includes any one of the above-mentioned secondary batteries.

[0024] The utility model also provides an electronic device, which includes the above-mentioned battery pack.

[0025] In the secondary battery of the present invention, the first covering layer is coated on the end face of the first end of the electrode assembly, and there is no barrier of the current collecting component, so that the first covering layer and the end face of the first end are more closely fitted. In particular, when the first covering layer is at least partially located between the current collecting component and the electrode assembly, the current collecting component also has a compression effect on the first covering layer, which can further improve the adhesion of the first covering layer to the end face of the first end. In addition, the second covering layer extends from the outer peripheral edge of the first covering layer along the axial direction of the electrode assembly and is coated on the outer peripheral surface of the electrode assembly. Therefore, the fixing force of the insulating layer on the outside of the electrode assembly is significantly improved, reducing the probability of the electrolyte flowing directly from the gap between the current collecting component and the insulating glue to the outermost circle of the electrode assembly, and alleviating the technical problem of the generation of metal dendrites on the negative electrode side diaphragm. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other embodiments can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 This is a schematic diagram of the overall structure of an example of a secondary battery of the present invention;

[0028] Figure 2 This is a schematic diagram of the structure of an electrode assembly of an example of a secondary battery of the present invention;

[0029] Figure 3 This is a schematic diagram of the coordinated structure of the electrode assembly, current collecting member and insulating layer of an example of the secondary battery of the present invention;

[0030] Figure 4 for Figure 1 A partial enlarged view of point A in the middle;

[0031] Figure 5 The insulating layer of an example of the secondary battery of the present invention is in the expanded state Figure 3 A top view of

[0032] Figure 6 for Figure 5 Schematic diagram of the middle insulation layer in the expanded state;

[0033] Figure 7 The insulating layer of an example of the secondary battery of the present invention is in the expanded state Figure 3 A top view of

[0034] Figure 8 for Figure 7 Schematic diagram of the middle insulation layer in the expanded state;

[0035] Figure 9 The insulating layer of an example of the secondary battery of the present invention is in the expanded state Figure 3 A top view of

[0036] Figure 10 for Figure 9 Schematic diagram of the middle insulation layer in the expanded state;

[0037] Figure 11 A schematic diagram of an example of a battery pack of the present invention;

[0038] Figure 12 FIG. 1 is a schematic diagram of an example of the electronic device of the present invention.

[0039] Component number description

[0040] 1. Electronic device; 10. Battery pack; 11. Working unit; 101. Housing; 102. Housing cover; 100. Secondary battery; 110. Housing; 111. End wall; 112. Side wall; 113. Opening; 120. Electrode assembly; 121. First electrode piece; 1211. Positive electrode current collector; 1212. First coated area; 1213. First uncoated area; 122. Separator; 123. Second electrode piece; 1231. Negative electrode current collector; 1232. Second coated area; 1233. Second uncoated area; 124. First pole ear; 125. Second pole ear; 126. Winding structure; 127. First end; 130. Insulating layer; 131. First coating layer; 1311. Overlapping portion; 1312. Welding print avoidance area; 132. Second coating layer; 1321. Sub-patch; 140. Current collecting component; 141. Welding print; 142. Through hole; 150. Pole; 160. End cover. DETAILED DESCRIPTION

[0041] The following describes the implementation of the present invention through specific examples. 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 implementation methods. The details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following examples and the features in the examples can be combined with each other unless there is a conflict. It should also be understood that the terms used in the examples of the present invention are for the purpose of describing specific implementation methods, not for the purpose of limiting the scope of protection of the present invention. The test methods for which specific conditions are not specified in the following examples are generally carried out under conventional conditions or under the conditions recommended by the manufacturers.

[0042] When numerical ranges are given in the examples, it should be understood that unless otherwise specified herein, both endpoints of each numerical range and any value between the endpoints may be used. Unless otherwise defined, all technical and scientific terms used in this utility model are consistent with the prior art as understood by those skilled in the art and the description of this utility model. Any prior art methods, equipment, and materials similar or equivalent to those in the examples of this utility model may also be used to implement this utility model.

[0043] 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 invention. Changes or adjustments to their relative relationships should be regarded as the scope of implementation of the present invention without substantially changing the technical content.

[0044] A secondary battery includes an electrode assembly, which is a component where electrochemical reactions occur in the secondary battery and may include one or more electrode assemblies.

[0045] The secondary battery also includes a shell, an end cover and a pole. The shell includes an end wall and a side wall surrounding the end wall. One end of the side wall has an opening. The electrode assembly can be assembled into the shell through the opening of the shell. The end cover is used to cover the opening of the shell to achieve sealing. The pole passes through the end wall and is electrically connected to the electrode assembly to conduct the electrical energy generated by the electrode assembly.

[0046] Usually, after the current collecting component is welded to the positive end of the electrode assembly, an insulating layer is coated on the periphery of the electrode assembly to isolate the positive electrode tab and the shell. The insulating layer usually also covers the periphery of the current collecting component. However, the inventors found that due to the hollow structure on the current collecting component, some electrolyte will be accommodated in the gap between the hollow structure and the insulating layer, and the insulating layer is prone to debonding when immersed in the electrolyte; and because the insulating layer and the electrode assembly are separated by the current collecting component, the insulating layer and the periphery of the electrode assembly are not tightly bonded, and the electrolyte containing metal ions will flow directly from the gap between the current collecting component and the insulating layer to the outermost circle of the electrode assembly, causing the metal ions to be reduced on the negative electrode side diaphragm and generate metal dendrites, which then pierce the diaphragm and cause an internal short circuit in the electrode assembly.

[0047] In view of this, the present invention provides a technical solution, wherein the insulating layer includes an integrally formed first coating layer and a second coating layer to isolate the first electrode tab from the housing. The first coating layer coats the end face of the first end of the electrode assembly, and the first coating layer surrounds the current collecting member or is at least partially located between the current collecting member and the electrode assembly. Without the barrier of the current collecting member, the first coating layer and the end face of the first end fit more closely. This reduces the probability of electrolyte flowing directly from the gap between the current collecting member and the insulating adhesive to the outermost ring of the electrode assembly, alleviating the technical problem of metal dendrites forming on the negative electrode side diaphragm.

[0048] See also Figures 1 to 12 The present invention provides a secondary battery 100 , which includes a housing 110 , an electrode assembly 120 , an insulating layer 130 , a current collecting member 140 , a terminal post 150 , and an end cover 160 .

[0049] See also Figure 1The housing 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 a variety of ways, as long as a stable seal and electrical connection can be established, such as integral stamping, integral casting, or separate welding. The shape of the side wall 112 is not limited and can be cylindrical or prismatic, or can be formed along any other closed-loop contour that matches the end wall 111. In this embodiment, the outer edge of the end wall 111 is circular, and the side wall 112 is cylindrical and surrounds the outer edge of the end wall 111. A circular opening 113 is formed at the end of the side wall 112 facing away from the end wall 111. A cavity is formed within the housing 110, enclosed by the end wall 111 and the side wall 112, for accommodating the electrode assembly 120, electrolyte, and other essential battery components. Specifically, the diameter of the housing 110 can be determined based on the specific dimensions of the electrode assembly 120, such as 18 mm, 21 mm, 46 mm, etc. The shell 110 can be made of various 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 can be plated on the surface of the shell 110.

[0050] See also Figures 1 to 3 The electrode assembly 120 is housed in the housing 110. The electrode assembly 120 is a component where electrochemical reactions occur in the secondary battery 100. The housing 110 may contain one or more electrode assemblies 120. The electrode assembly 120 includes a first electrode sheet 121, a second electrode sheet 123, and a separator 122 stacked and wound to form a wound structure 126. The first electrode sheet 121 and the second electrode sheet 123 have opposite polarities. In some embodiments, the first electrode sheet 121 is a positive electrode sheet and the second electrode sheet 123 is a negative electrode sheet. In other embodiments, the first electrode sheet 121 is a negative electrode sheet and the second electrode sheet 123 is a positive electrode sheet.

[0051] See also Figures 1 to 3 In this embodiment, the first electrode sheet 121 is a positive electrode sheet. Specifically, the first electrode sheet 121 includes a positive electrode current collector 1211 and a positive electrode active material. The positive electrode active material is coated on the surface of the positive electrode current collector 1211; the positive electrode current collector 1211 includes a first coated area 1212 coated with the active material and a first uncoated area 1213 not coated with the active material. The first uncoated area 1213 is located at the end of the first electrode sheet 121. The first uncoated area 1213 extends out of the diaphragm 122 along the axial direction of the electrode assembly 120 and is bent to form a first electrode tab 124. The first electrode tab 124 is the corresponding positive electrode tab. The end where the first electrode tab 124 is located is defined as the first end 127 of the electrode assembly 120.

[0052] See also Figures 1 to 2In this embodiment, the second electrode sheet 123 is a negative electrode sheet, and the second electrode sheet 123 includes a negative electrode current collector 1231 and a negative electrode active material. The negative electrode active material is coated on the surface of the negative electrode current collector 1231; the negative electrode current collector 1231 includes a second coated area 1232 coated with the active material and a second uncoated area 1233 not coated with the active material. The second uncoated area 1233 is located at the end of the second electrode sheet 123. The second uncoated area 1233 extends out of the separator 122 along the winding axis direction of the electrode assembly 120 and is bent toward the winding axis to form a second electrode tab 125. The second electrode tab 125 is the corresponding negative electrode tab.

[0053] See also Figures 1 to 2 The separator 122 is disposed between the first electrode sheet 121 and the second electrode sheet 123 to separate the positive electrode active material layer from 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, and the positive electrode active material layer includes a positive electrode active material, which can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide. The material of the negative electrode current collector 1231 can be copper, and the negative electrode active material layer includes a negative electrode active material, which can be carbon or silicon. The base material of the separator 122 can be polypropylene (PP) or polyethylene (PE), etc. To provide protection and insulation for the electrode assembly 120, an insulating film can also be coated on the outside of the electrode assembly 120. The insulating film can be synthesized from PP, PE, polyethylene terephthalate (PET), polyvinyl chloride (PVC), or other polymer materials.

[0054] See also Figure 1 and Figure 3 Furthermore, in the present invention, the first tab 124 faces the end wall 111 or the opening 113, while the second tab 125 faces the other end of the housing 110. In this embodiment, the first tab 124 faces the end wall 111 and is electrically connected to the pole 150, causing the pole 150 to be positively charged. The second tab 125 faces the opening 113, and the housing 110 is electrically connected to the second tab 125, causing the housing 110 to be negatively charged. However, in other embodiments, the second tab 125 may be connected to the pole 150, while the first tab 124 is connected to the housing 110.

[0055] See also Figures 3 and 4In order to prevent the first electrode tab 124 and the shell 110 from being connected and causing a short circuit, an insulating layer 130 is coated on the first end 127 of the electrode assembly 120. Specifically, the insulating layer 130 includes an integrally formed first coating layer 131 and a second coating layer 132 to isolate the first electrode tab 124 from the shell 110. The first coating layer 131 is coated on the end surface of the first end 127 of the electrode assembly 120, and the second coating layer 132 extends from the outer peripheral edge of the first coating layer 131 along the axial direction of the electrode assembly 120 and is coated on the outer peripheral surface of the electrode assembly 120. It can be understood that the arrangement of the first coating layer 131 and the second coating layer 132 can restrain each other, so as to obtain a larger fixing force on both the end surface of the first end 127 and the outer surface of the side wall 112.

[0056] See also Figures 3 to 5 The current collecting member 140 is welded to the first electrode tab 124. The welding method can be ultrasonic welding, resistance welding, laser welding, or the like, without limitation. In this embodiment, laser welding is used. The first electrode tab 124 is the positive electrode tab. Aluminum is preferably selected as the material for the current collecting member 140. It should be noted that the shape of the current collecting member 140 can be any rotationally symmetrical shape, such as a circle, square, regular polygon, petal, or other shape with a center of symmetry that can be reconstructed after being rotated a certain angle around the center of symmetry. This is not limited to any shape that can achieve a stable and reliable electrical connection. The center of the current collecting member 140 is its own center of symmetry. To improve positioning, ease of processing, interchangeability, and uniformity during installation, the current collecting member 140 in this embodiment adopts a circular structure. Multiple through-holes 142 are provided on the current collecting member 140 to provide expansion space and improve current flow capacity.

[0057] See also Figure 1 In this embodiment, the secondary battery 100 further includes a pole 150. Specifically, the pole 150 passes through the end wall 111 and is insulated from the end wall 111. One end of the pole 150 facing the electrode assembly 120 passes through the end wall 111 and is electrically connected to the first pole tab 124 via the current collecting member 140. The structure of the pole 150 can be any suitable form that can pass through the end wall 111 and be electrically connected to the first pole tab 124 of the electrode assembly 120. For example, the cross-section can be circular, square, prismatic, or a special-shaped profile that can achieve stable conductivity. The hole in the pole 150 corresponds to the shape of the pole 150. In this embodiment, the cross-section of the pole 150 is circular.

[0058] See also Figure 1In this embodiment, the secondary battery 100 further includes an end cap 160, which is sealed against the opening 113. The outer edge of the end cap 160 corresponds to the shape of the opening 113 and is connected to the side wall 112 to seal the opening 113. In some embodiments, the end cap 160 and the side wall 112 are pressed tightly together using a pier seal to form a reliable seal. In other embodiments, the end cap 160 and the side wall 112 are sealed and fixed together using welding, which is not limited to this. In this embodiment, the end cap 160 and the side wall 112 are connected by welding.

[0059] Considering the structure in which the outer periphery of the current collecting component 140 is wrapped in the insulating layer 130, the insulating layer 130 passes through the step of the outer periphery of the component when being pasted to the end face of the first end 127, so that there is a gap between the insulating layer 130 and the end face of the first end 127. Electrolyte is easily retained in the gap. When immersed in the electrolyte, the insulating layer 130 is easy to debond, and there is a risk that the electrolyte containing metal ions directly flows into the outermost side of the electrode assembly 120, resulting in the problem of metal dendrites being generated on the negative electrode side diaphragm 122.

[0060] In this example, see Figures 5 to 10 , the first coating layer 131 is disposed around the current collecting member 140 or is at least partially located between the current collecting member 140 and the electrode assembly 120 , that is, the first coating layer 131 does not overlap with the current collecting member 140 , as shown in FIG. Figure 7 and Figure 8 Or the first coating layer 131 overlaps with the current collecting member 140, as shown. Figure 5 and Figure 6 As shown, the first covering layer 131 is located between the current collecting member 140 and the electrode assembly 120. Both of the above arrangements can prevent the current collecting member 140 from being spaced between the first covering layer 131 and the electrode assembly 120, allowing the first covering layer 131 to more closely fit the end surface of the first end 127. In particular, when the first covering layer 131 is at least partially located between the current collecting member 140 and the electrode assembly 120, the current collecting member 140 also has a compressive effect on the first covering layer 131, which can further improve the adhesion of the first covering layer 131 to the end surface of the first end 127. In addition, the second covering layer 132 extends from the outer peripheral edge of the first covering layer 131 along the axial direction of the electrode assembly 120 and covers the outer peripheral surface of the electrode assembly 120. Therefore, the fixing force of the insulating layer 130 on the outside of the electrode assembly 120 is significantly improved, reducing the probability of the electrolyte flowing directly from the gap between the current collecting component 140 and the insulating glue to the outermost circle of the electrode assembly 120, and alleviating the technical problem of generating metal dendrites on the negative electrode side diaphragm 122.

[0061] Since the first coating layer 131 and the second coating layer 132 are integrally formed, if a conventionally shaped insulating layer 130 is used to cover the first end 127 of the electrode assembly 120, the second coating layer 132 will be flat, but the first coating layer 131 will be wrinkled. Figures 5 to 10 The first coating layer 131 is annular. This annular shape matches the shape of the first end 127, improving the flatness of the insulating tape on the end surface of the first end 127 and preventing wrinkles there. This allows the first coating layer 131 to fit more closely with the end surface of the first end 127, further enhancing the securing force of the insulating layer 130 on the outer side of the electrode assembly 120. Furthermore, this reduces the risk of liquid accumulation between the insulating layer 130 and the electrode assembly 120, alleviating the problem of the first coating layer 131 being easily debonded due to liquid accumulation, thereby reducing the risk of electrolyte flowing directly from between the insulating layer 130 and the electrode assembly 120 to the outermost circle of the electrode assembly 120.

[0062] Furthermore, since the first coating layer 131 and the second coating layer 132 are integrally formed, the first coating layer 131 is annular. If the second coating layer 132 adopts a conventional shape, it is easy to cause wrinkles in the second coating layer 132. In an example of the secondary battery 100 of the present invention, please refer to Figures 5 to 10 The second coating layer 132 includes n sub-patches 1321, where n ≥ 2. The n sub-patches 1321 are connected to the outer periphery of the first coating layer 131 and are distributed along the circumference of the first coating layer 131. It can be understood that the coating process of the insulating layer 130 in this embodiment is that after the first coating layer 131 is first adhered to the end surface of the first end 127, the n sub-patches 1321 are then coated on the outside of the side wall 112 along the axial direction of the shell 110 away from the first coating layer 131. This arrangement can reduce the possibility of wrinkles on the side wall 112 of the second coating layer 132, making the appearance of the electrode assembly 120 more beautiful and more convenient for shell insertion. It should be noted that the number n is not limited and can be any natural number greater than or equal to 2, which can all have the effect of reducing wrinkles.

[0063] See also Figures 5 to 10In an example of the secondary battery 100 of the present invention, preferably, in the unfolded state of the insulating layer 130, the inner peripheries of each adjacent sub-patch 1321 are connected, and along the radial direction of the first covering layer 131, the arc length on each sub-patch 1321 is equal everywhere, that is, the arc length of each sub-patch 1321 connected to the first covering layer 131 is equal to the arc length of the outer periphery of the sub-patch 1321, and the two opposite radial sides are parallel; the arc length of each sub-patch 1321 is Li, and the diameter of the outer periphery of the first covering layer 131 is d, L1=L2=…=Li, and Li×n=πd, so that when n sub-patches 1321 are covered on the side wall 112, the outer peripheries of all sub-patches 1321 can be exactly connected and equal to the circumference of the side wall 112, so that there is no gap or overlap between each sub-patch 1321. This setting is both beautiful and can achieve a better covering and fixing effect.

[0064] Considering that the first tab 124 is formed by extending out of the separator 122 along the axial direction of the electrode assembly 120 and being bent, the first tab 124 of each circle can be partially covered and overlapped by the first tab 124 of the outer circle. Only the first tab 124 on the outermost circle is in a free state. Even if the current collecting member 140 is welded to the first tab 124 later, the first tab 124 on the outermost circle is still at risk of warping, or even breaking and falling into the housing 110, causing a short circuit. In an example of the secondary battery 100 of the present invention, please refer to Figure 3 and Figure 5 The first coating layer 131 covers at least the outermost ring of the first electrode tab 124. This arrangement can restrict and fix the outermost ring of the first electrode tab 124, preventing the first electrode tab 124 from connecting with the housing 110 and causing a short circuit, and also reducing the risk of the outermost ring of the first electrode tab 124 breaking and falling into the battery interior and causing a short circuit.

[0065] See also Figure 5 and Figure 7 In one example of the secondary battery 100 of the present invention, the current collecting member 140 is welded to the first electrode tab 124, forming a weld mark 141. The inner periphery of the first cladding layer 131 is located outside the weld mark 141. The shortest distance from the inner periphery of the first cladding layer 131 to the weld mark 141 is a, where a ≥ 2 mm. Specifically, the preferred processing technique is to first attach the insulating layer 130 to the electrode assembly 120 before welding the current collecting member 140 to the first electrode tab 124. This arrangement allows the first cladding layer 131 to avoid the weld mark 141, reducing the risk of thermal impact. Preferably, the requirement of a ≥ 2 mm maintains a safe welding distance between the first cladding layer 131 and the weld mark 141.

[0066] See also Figures 4 and 5In one example of the secondary battery 100 of the present invention, the first cladding layer 131 includes an overlapping portion 1311 that overlaps with the current collecting member 140. Specifically, the first cladding layer 131 is positioned between the current collecting member 140 and the first electrode tab 124. Without the barrier of the current collecting member 140, the first cladding layer 131 and the end surface of the first end 127 are more closely aligned. Furthermore, the overlapping portion 1311 provides a compressive effect on the current collecting member 140 against the first cladding layer 131, further enhancing the adhesion of the first cladding layer 131 to the end surface of the first end 127 and reducing the risk of debonding of the insulating layer 130. The overlapping portion 1311 is annular, with a ring width b, where 0 mm < b ≤ 5 mm. b falling within this range not only ensures overlap between the insulating layer 130 and the current collecting member 140, but also maintains a safe welding distance between the first cladding layer 131 and the weld mark 141.

[0067] See also Figures 9 and 10 In an example of the secondary battery 100 of the present invention, the ring width of the first cladding layer 131 is c, 0.5 mm ≤ c ≤ 22.5 mm, and the current collecting member 140 and the first pole tab 124 are welded to form a weld mark 141. It can be understood that, projected toward the first end 127 along the axial direction of the electrode assembly 120, the first cladding layer 131 and the weld mark 141 may have no overlapping area or may have an overlapping area within the above-mentioned range. Therefore, when the first cladding layer 131 and the weld mark 141 have an overlapping area, a weld mark avoidance area 1312 corresponding to the weld mark 141 is provided on the first cladding layer 131 for welding the current collecting member 140 to the first pole tab 124. The setting of c ≥ 0.5 mm enables the first cladding layer 131 to have a width of at least 0.5 mm, thereby isolating the first electrode tab 124 from the housing 110 and preventing the electrolyte from flowing directly into the outermost portion of the electrode assembly 120. c ≤ 22.5 mm defines the maximum ring width of the first cladding layer 131. This range is limited by the radius of the electrode assembly 120. The first cladding layer 131 within this range can achieve better insulation and electrolyte blocking effects. The provision of the weld mark avoidance area 1312 enables the first cladding layer 131 to avoid the weld mark 141 formed by the weld between the current collecting member 140 and the first electrode tab 124, thereby preventing the risk of the first cladding layer 131 being affected by heat during welding. It should be noted that the shape of the weld avoidance area is not limited and can be rectangular, waist-shaped, elliptical, or other irregular shapes, as long as the weld mark 141 can be avoided.

[0068] See also Figure 4In one example of the secondary battery 100 of the present invention, the height of the second covering layer 132 along the axial direction of the electrode assembly 120 is defined as e, where 0.1 mm < e ≤ 120 mm. The setting of e > 0.1 mm ensures that the second covering layer 132 has a height of at least 0.1 mm, thereby isolating the outer periphery of the first end 127 of the electrode assembly 120 from contact with the housing 110 and enhancing the securing force of the insulating layer 130 to the first end 127 of the electrode assembly 120. The maximum height of the second covering layer 132 is defined by e ≤ 120 mm. This range is limited by the height of the electrode assembly 120, and within this range, the second covering layer 132 can effectively secure the outer periphery of the electrode assembly 120.

[0069] See also Figure 11 The present invention further provides a battery pack 10, which includes any of the aforementioned secondary batteries 100. In one embodiment of the present invention's battery pack 10, the battery pack 10 includes a housing 101, a housing cover 102, and a plurality of secondary batteries 100. The plurality of secondary batteries 100 are placed in the housing 101 and are connected in series or in parallel, or in a combination of series and parallel. The housing cover 102 seals the housing 101 to protect the plurality of secondary batteries 100. It should be noted that, in addition to the present invention's secondary batteries 100, the battery pack 10 may also include a battery pack 10 thermal management system, a circuit board, and other components. The battery pack 10 may be a battery module, a battery pack, an energy storage cabinet, or the like; these will not be described in detail here.

[0070] See also Figure 12The present invention 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 electrical energy 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 the vehicle body, and the battery pack 10 is arranged at the bottom of the vehicle body and provides electrical energy 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 spacecraft, etc.; the working part 11 can be a unit component that can obtain electrical energy from the battery pack 10 and perform corresponding work, such as a fan blade rotation unit, a vacuum cleaner suction unit, etc. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric boat toys, and electric airplane toys; electric tools include metal cutting tools, grinding tools, assembly tools, and railway tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers. The present embodiment does not impose any particular restrictions on the electronic device 1.

[0071] In the secondary battery of the present invention, the first coating layer is coated on the end face of the first end of the electrode assembly, and there is no barrier of the current collecting component, so that the first coating layer and the end face of the first end are more closely fitted. In addition, the second coating layer extends from the outer peripheral edge of the first coating layer along the axial direction of the electrode assembly and is coated on the outer peripheral surface of the electrode assembly. Therefore, the fixing force of the insulating layer on the outside of the electrode assembly is significantly improved, which reduces the probability of the electrolyte flowing directly from the gap between the current collecting component and the insulating glue to the outermost circle of the electrode assembly, and alleviates the technical problem of generating metal dendrites on the negative electrode side diaphragm. Therefore, the present invention effectively overcomes some practical problems in the prior art and has high utilization value and use significance. The above embodiments only illustrate the principles and effects of the present invention, and are not used to limit the present invention. Anyone familiar with this 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 skilled in the art without departing from the spirit and technical ideas disclosed in 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 housed in the housing, the electrode assembly comprising a first electrode sheet, a second electrode sheet, and a diaphragm stacked and wound to form a wound structure, the first end of the electrode assembly comprising a first electrode tab extending axially from the diaphragm and bent; an insulating layer, comprising an integrally formed first covering layer and a second covering layer to insulate the first tab from the shell, the first covering layer covering an end surface of the first end of the electrode assembly, and the second covering layer extending from an outer peripheral edge of the first covering layer along an axial direction of the electrode assembly and covering an outer peripheral surface of the electrode assembly; a current collecting component, welded to the first electrode tab; The first coating layer is disposed around the current collecting member or is at least partially located between the current collecting member and the electrode assembly.

2. The secondary battery according to claim 1, wherein The first cladding layer is annular.

3. The secondary battery according to claim 2, wherein The second cladding layer includes n sub-patches, wherein n≥2, and the n sub-patches are connected to the outer periphery of the first cladding layer and are distributed along the circumference of the first cladding layer.

4. The secondary battery according to claim 3, wherein When the insulating layer is expanded, the inner peripheries of each adjacent sub-patch are connected, and along the radial direction of the first covering layer, the arc length on each sub-patch is equal everywhere. The arc length of each sub-patch is Li, and the diameter of the outer periphery of the first covering layer is d, wherein L1=L2=…=Li, and Li×n=πd.

5. The secondary battery according to claim 2, wherein The first coating layer covers at least the outermost circle of the first electrode tab.

6. The secondary battery according to claim 5, characterized in that The current collecting member and the first tab are welded to form a weld mark, the inner periphery of the first cladding layer is located outside the weld mark, and the shortest distance from the inner periphery of the first cladding layer to the weld mark is a, where a≥2 mm.

7. The secondary battery according to claim 6, characterized in that The first coating layer includes an overlapping portion overlapping with the current collecting component, the overlapping portion is in a circular ring shape, and the ring width of the overlapping portion is b, wherein 0mm<b≤5mm.

8. The secondary battery according to claim 2, wherein The ring width of the first covering layer is c, where 0.5 mm ≤ c ≤ 22.5 mm. The current collecting member and the first electrode tab are welded to form a weld mark, which is projected toward the first end along the axial direction of the electrode assembly. When the first covering layer and the weld mark have an overlapping area, a weld mark avoidance area corresponding to the weld mark is provided on the first covering layer.

9. The secondary battery according to claim 1, wherein Along the axial direction of the electrode assembly, the height of the second coating layer is e, wherein 0.1 mm < e ≤ 120 mm.

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

11. An electronic device, characterized in that: A battery pack comprising the battery pack according to claim 10.

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