Secondary battery

Abstract

The embodiment of the utility model provides a secondary battery which comprises the following components: a housing which comprises a first wall and a second wall which are oppositely arranged along a first direction; the at least two roll core groups are accommodated in the shell and are stacked in the first direction, and each roll core group comprises at least two roll cores which are stacked in the first direction; the peripheral surface of each roll core comprises two straight sections which are oppositely arranged along a first direction, and a first corner section and a second corner section which are connected with the two straight sections and are respectively positioned on opposite sides of the roll core along a second direction, and the second direction is perpendicular to the first direction; the insulating tape covers at least one part of the first corner section and at least one part of the second corner section of each winding core in the at least two winding core groups; each winding core group further comprises a lacing belt, and the lacing belt covers at least one part of the first corner section and at least one part of the second corner section of each winding core in the winding core group. According to the technical scheme, at least the lithium precipitation problem of the secondary battery can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of batteries, and more particularly, a secondary battery is provided. BACKGROUND

[0002] With the increasing demand of the energy storage market, the development of large-capacity secondary batteries is also constantly iterating. In the currently common mass-produced products, due to the limitations of process and other reasons, secondary batteries with multiple winding cores are often used. With the increase of the volume of the battery, the secondary battery including multiple winding cores becomes the main concern of the development of large-capacity secondary batteries. However, the corner regions of multiple winding cores are prone to lithium precipitation problems. CONTENT OF THE UTILITY MODEL

[0003] In view of the above problems existing in the prior art, the present application provides a secondary battery, which can at least improve the lithium precipitation problem of the secondary battery.

[0004] According to one aspect of the present application, a secondary battery is provided, which comprises: a shell; at least two winding core groups accommodated in the shell and stacked along a first direction, each winding core group comprising at least two winding cores stacked along the first direction, an outer peripheral surface of each winding core comprising two flat sections oppositely arranged along the first direction, and a first corner section and a second corner section connecting the two flat sections and respectively located on opposite sides of the winding core along a second direction, the second direction being perpendicular to the first direction; and an insulation tape covering at least a portion of the first corner section and at least a portion of the second corner section of each winding core in the at least two winding core groups; wherein each winding core group further comprises a tightening tape, the tightening tape being spaced apart from the insulation tape in a third direction, the third direction being perpendicular to the first direction and the second direction, the tightening tape covering at least a portion of the first corner section and at least a portion of the second corner section of each winding core in the winding core group.

[0005] In some embodiments, each winding core is formed by winding a positive electrode sheet, a negative electrode sheet, and a separator between the positive electrode sheet and the negative electrode sheet, the insulation tape, the tightening tape, and the separator each having a width in the third direction, and the sum of the width of the insulation tape and the width of the tightening tape is 60%-90% of the width of the separator of any winding core.

[0006] In some embodiments, the insulation tape comprises a plurality of sub-insulation tapes, the plurality of sub-insulation tapes being spaced apart along the third direction.

[0007] In some embodiments, along the third direction, the tightening tape is disposed between and spaced apart from two sub-insulation tapes.

[0008] In some embodiments, in a cross-section defined by the first direction and the second direction, the insulation tape surrounds the at least two winding core groups.

[0009] In some embodiments, the tightening band comprises a first sub-tightening band and a second sub-tightening band, the first sub-tightening band covers at least a portion of the first corner section of each jelly-roll in the jelly-roll group, and the second sub-tightening band covers at least a portion of the second corner section of each jelly-roll in the jelly-roll group.

[0010] In some embodiments, the shell comprises a first wall and a second wall oppositely arranged along a first direction, a jelly-roll adjacent to the first wall along the first direction in the jelly-roll group is a first jelly-roll, and a jelly-roll adjacent to the second wall along the first direction is a second jelly-roll, a flat section adjacent to the first wall of the first jelly-roll is a first flat section, one end of the first sub-tightening band extends to the first flat section via the first corner section of the first jelly-roll, one end of the second sub-tightening band extends to the first flat section via the second corner section of the first jelly-roll, and the one end of the first sub-tightening band and the one end of the second sub-tightening band are spaced apart along a second direction.

[0011] In some embodiments, a flat section adjacent to the second wall of the second jelly-roll is a second flat section, the other end of the first sub-tightening band extends to the second flat section via the first corner section of the second jelly-roll, the other end of the second sub-tightening band extends to the second flat section via the second corner section of the second jelly-roll, and the other end of the first sub-tightening band and the other end of the second sub-tightening band are spaced apart along the second direction.

[0012] In some embodiments, the secondary battery further comprises: a first heat dissipation material layer located between adjacent two jelly-rolls in each jelly-roll group along the first direction.

[0013] In some embodiments, the secondary battery further comprises: a second heat dissipation material layer located between adjacent two jelly-roll groups in the at least two jelly-roll groups along the first direction.

[0014] The above technical solutions of the present application cover the corner sections of the jelly-rolls with the insulating bands, increase the tightening effect of the corner sections of the jelly-rolls, make the jelly-rolls at the corner sections fit more closely, and improve the lithium precipitation phenomenon. In addition, the fixing effect on the jelly-rolls can be further strengthened, and the structural stability of the jelly-rolls can be further strengthened. Moreover, the process difficulty of arranging the insulating bands is low, and the overall processing and manufacturing of the prismatic battery are facilitated. In addition, by arranging the tightening bands in each jelly-roll group, the tightening effect of the corner sections of the jelly-rolls in the jelly-roll group can be further increased, the jelly-rolls at the corner sections can fit more closely, and the lithium precipitation phenomenon can be improved. In addition, the fixing effect on the jelly-rolls in the jelly-roll group can be further strengthened, and the structural stability can be further strengthened. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to describe the technical solutions of the embodiments of the present application or the prior art more clearly, the accompanying drawings needed in the embodiments will be briefly introduced as follows. Obviously, the accompanying drawings in the following description only need to be some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings. It should be noted that, according to the standard practice in the industry, various components are not drawn to scale and are for illustrative purposes only. In fact, for the sake of clarity of discussion, the size of each component can be arbitrarily increased or decreased.

[0016] FIG. 1A-1 and FIG. 1A-2 are cross-sectional schematic views of a secondary battery according to an embodiment of the present application.

[0017] FIG. 1B is a front view schematic view of the jelly-roll of the secondary battery in FIG. 1A-1

[0018] FIG. 1C is a front view schematic view of the jelly-roll of the secondary battery in FIG. 1A-1

[0019] FIG. 1D is a top view schematic view of the jelly-roll of the secondary battery in FIG. 1A-1

[0020] FIG. 1E is a bottom view schematic view of the jelly-roll of the secondary battery in FIG. 1A-1

[0021] FIG. 2 is an enlarged cross-sectional schematic view of the jelly-roll of a secondary battery according to an embodiment of the present application.

[0022] FIG. 3 is a cross-sectional schematic view of a secondary battery according to another embodiment of the present application.

[0023] FIG. 4A and FIG. 4B are front view schematic views of a secondary battery according to another embodiment of the present application.

[0024] FIG. 4C and FIG. 4D are top view schematic view and bottom view schematic view of a secondary battery according to another embodiment of the present application. DETAILED DESCRIPTION

[0025] ​​​​With reference to the drawings and embodiments described below, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art belong to the scope of protection of the present application.

[0026] The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of elements and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, in the following description, forming a first component over or on a second component can include embodiments where the first component and the second component are in direct contact, and can also include embodiments where additional components are formed between the first component and the second component such that the first component and the second component can not be in direct contact. Furthermore, the present application can refer to a number and / or letter in various examples. Such repetition is only to make the description clear and concise, and does not represent the relationship between the various embodiments and / or arrangements discussed.

[0027] In addition, the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and in combination with the embodiments. It should be understood that the specific structures shown in the drawings are only for the purpose of illustration and are not intended to limit the present application. When a specific figure is described, other structures shown in the figure that are not described can be set according to actual needs and are not intended to limit the present application.

[0028] For a secondary battery including a plurality of winding cores (for example, at least 4 winding cores), since the corner area of the winding core is not subjected to heat pressing treatment, the contact between the pole piece and the separator of the winding core in the corner area is loose and the gap is large, and the phenomenon of lithium precipitation on the surface of the negative pole piece in the corner area is more serious in long-term cycling, which affects the performance of the battery. However, the conventional technology has deficiencies in improvement effect, cost and process for controlling lithium precipitation in the corner area.

[0029] Embodiments of the present application provide a secondary battery. FIG. 1A-1 and FIG. 1A-2 are respectively a cross-sectional schematic view of a secondary battery 100A according to an embodiment of the present application. FIG. 1B is FIG. 1A-1 is a front view schematic view of the winding core of the secondary battery 100A in FIG. 1C is FIG. 1A-1 is a front view schematic view of the winding core of the secondary battery 100A in FIG. 1D is FIG. 1A-1 is a top view schematic view of the winding core of the secondary battery 100A in FIG. 1E isFIG. 1A-1 A bottom view of the winding core of the 100A secondary battery in the diagram, on the side opposite to the cross section CC. FIG. 1A-1 The cross section is FIG. 1D The cross-sectional view at section A1-A1 in the diagram. FIG. 1A-2 The cross section is FIG. 1D The cross-sectional view at section A2-A2 is shown. For clarity, the shell is not shown in the front view, top view, and bottom view.

[0030] refer to FIG. 1A-1 and FIG. 1A-2 As shown, the secondary battery 100A may include a housing 110 and at least two core groups housed within the housing 110. In this embodiment, a first core group 310 and a second core group 320 are shown as examples. The first core group 310 and the second core group 320 are stacked along a first direction Z. The first core group 310 and the second core group 320 may each include at least two cores stacked along the first direction Z. In this embodiment, the first core group 310 and the second core group 320 each include two cores as examples.

[0031] Specifically, the housing 110 includes a first wall 112 and a second wall 114 disposed opposite each other along a first direction Z. In the first core assembly 310, the first core assembly 310 includes a first core 210 adjacent to the first wall 112 and a second core 230 adjacent to the second wall 114; that is, in the first core assembly 310, the core adjacent to the first wall 112 and located above is the first core 210, and the core adjacent to the second wall 114 and located below is the second core 230. Similarly, the second core assembly 320 includes a first core 220 adjacent to the first wall 112 and a second core 240 adjacent to the second wall 114.

[0032] The structures of the first core 210 and the second core 230 of the first core group 310 and the first core 220 and the second core 240 of the second core group 320 can be similar, as will be referred to below. FIG. 2 The core structure is illustrated using the first core 210. FIG. 2 An enlarged cross-sectional schematic diagram of the first core 210 is shown. (Reference) FIG. 2 As shown, the first core 210 can be formed by winding a positive electrode 201, a negative electrode 202, and a separator 204 between the positive electrode 201 and the negative electrode 202. In some embodiments, the secondary battery is a prismatic battery, and the first core 210 formed by winding has a flat rectangular shape. In some embodiments, the first direction Z is the thickness direction of the first core 210.

[0033] The outer circumferential surface of the first jelly-roll 210 is formed by the separator 204. The outer circumferential surface of the first jelly-roll 210 includes two flat sections 212, 214 disposed opposite to each other along the first direction Z, and a first corner section 216 and a second corner section 218 connecting the two flat sections 212, 214, the first corner section 216 and the second corner section 218 being located at opposite sides of the first jelly-roll 210 along the second direction X, respectively, the second direction X being perpendicular to the first direction Z.

[0034] Referring back to FIG. 1A-1 , similar to the first jelly-roll 210, the outer circumferential surface of the second jelly-roll 230 includes two flat sections disposed opposite to each other along the first direction Z, and a first corner section 236 and a second corner section 238 connecting the two flat sections, the first corner section 236 and the second corner section 238 being located at opposite sides of the second jelly-roll 230 along the second direction X. The outer circumferential surface of the first jelly-roll 220 of the second jelly-roll group 320 includes two flat sections disposed opposite to each other along the first direction Z, and a first corner section 226 and a second corner section 228 connecting the two flat sections, the first corner section 226 and the second corner section 228 being located at opposite sides of the first jelly-roll 220 along the second direction X. The outer circumferential surface of the second jelly-roll 240 includes two flat sections 242, 244 disposed opposite to each other along the first direction Z, and a first corner section 246 and a second corner section 248 connecting the two flat sections 242, 244, the first corner section 246 and the second corner section 248 being located at opposite sides of the second jelly-roll 240 along the second direction X. FIG. 1A-1 The junctions of the flat sections and the corner sections are shown as dotted lines extending along the first direction Z.

[0035] The secondary battery 100A can further include an insulating tape 150 covering at least a portion of the corner sections of each jelly-roll in the first jelly-roll group 310 and the second jelly-roll group 320. Specifically, the insulating tape 150 covers at least a portion of the first corner sections 216, 236 and at least a portion of the second corner sections 218, 238 of the first jelly-roll 210, the second jelly-roll 230 in the first jelly-roll group 310, and the insulating tape 150 further covers at least a portion of the first corner sections 226, 246 and at least a portion of the second corner sections 228, 248 of the first jelly-roll 220, the second jelly-roll 240 in the second jelly-roll group 320. In some embodiments, the insulating tape 150 can include a base and a glue layer, and the insulating tape 150 can be adhered to the surface of the jelly-roll by the glue layer.

[0036] Further, referring to FIG. 1A-2 and FIG. 1B to FIG. 1EEach of the winding core groups further comprises a binding belt. Specifically, the first winding core group 310 comprises a binding belt 181. The binding belt 181 covers at least a portion of the first corner segments 216, 236 and at least a portion of the second corner segments 218, 238 of the first winding core 210 and the second winding core 230 in the first winding core group 310. In the present embodiment, the binding belt 181 comprises a first sub-binding belt 181 A and a second sub-binding belt 181B. The first sub-binding belt 181 A covers at least a portion of the first corner segments 216, 236 of the first winding core 210 and the second winding core 230, and the second sub-binding belt 181B covers at least a portion of the second corner segments 218, 238 of the first winding core 210 and the second winding core 230.

[0037] The second winding core group 320 can comprise a binding belt 182. The binding belt 182 covers at least a portion of the first corner segments 226, 246 and at least a portion of the second corner segments 228, 248 of the first winding core 220 and the second winding core 240 in the second winding core group 320. In the present embodiment, the binding belt 182 comprises a first sub-binding belt 182A and a second sub-binding belt 182B. The first sub-binding belt 182A covers at least a portion of the first corner segments 226, 246 of the first winding core 220 and the second winding core 240, and the second sub-binding belt 182B covers at least a portion of the second corner segments 228, 248 of the first winding core 220 and the second winding core 240.

[0038] The above technical solutions of the present application increase the binding effect of the corner segments of the winding cores by covering the corner segments of the winding cores with the insulating belts 150, so that the pole pieces at the corner segments are better tightly fitted, which can improve the lithium precipitation phenomenon. In addition, the fixing effect on the winding cores can be further strengthened, and the structural stability of the winding cores can be further strengthened. Moreover, the process difficulty of setting the insulating belts 150 is low, which is convenient for the overall processing and manufacturing of the prismatic battery. In addition, by respectively setting the binding belts 181, 182 in the winding core groups, the binding effect of the corner segments of the winding cores in the winding core groups can be further increased, so that the pole pieces at the corner segments are better tightly fitted, which can improve the lithium precipitation phenomenon. In addition, the fixing effect on the winding cores in the winding core groups can be further strengthened, and the structural stability can be further strengthened.

[0039] In some embodiments, the thickness (in the first direction Z) of the insulating belt 150 ranges from 20 pm to 40 pm. In some embodiments, the insulating belt 150 is an adhesive layer with adhesive force. In some embodiments, the insulating belt 150 can comprise a substrate and a glue layer, as described above, wherein the thickness of the glue layer ranges from 5 pm to 20 pm, for example. In some embodiments, the adhesive force of the glue layer ranges from 1 N / cm to 10 N / cm.

[0040] In combination with FIG. 1A-1 to FIG. 1EAs shown, the tightening bands 181, 182 and the insulation band 150 are spaced apart in the third direction Y. The third direction Y is perpendicular to the first direction Z and the second direction X. The insulation band 150 has a width W1 in the third direction Y. The outer circumferential surface of each winding core is formed by the separator, and the separators 204 in the first winding core 210, 220 and the second winding core 230, 240 have a width W3 in the third direction Y. The tightening band 181 can have a width W2, and in some embodiments, the sum of the width W2 and the width W1 of the insulation band 150 can be 60%-90% of the width W3. The tightening band 182 can have a width W4, and in some embodiments, the sum of the width W4 and the width W1 can be 60%-90% of the width W3. In some embodiments, the width W2 and the width W4 can be the same, or can be different. Through the above width configuration of the tightening bands 181, 182 and the insulation band 150, the tightening bands 181, 182 and the insulation band 150 can be attached and covered on the corresponding corner section in a large area, and the tightening bands 181, 182 and the insulation band 150 can better tighten the corner section, so that the pole piece at the corner section is better tightly attached, so as to improve the lithium precipitation phenomenon.

[0041] Reference FIG. 1A-1 and FIG. 1A-2 In some embodiments, the secondary battery 100A can further include a first heat dissipation material layer 420, which is arranged between the first winding core 210 and the second winding core 230 of the first winding core group 310, and between the first winding core 220 and the second winding core 240 of the second winding core group 320 in the first direction Z. For a secondary battery including a plurality of winding cores, heat dissipation is difficult between adjacent winding cores in a winding core group. By arranging the first heat dissipation material layer 420 between adjacent winding cores in the winding core group, heat dissipation between adjacent winding cores in the winding core group can be improved.

[0042] In some embodiments, the heat dissipation material of the first heat dissipation material layer 420 is any one or more of aerogel, heat-conductive adhesive tape, heat-conductive rubber, heat-conductive sheet, heat-conductive pad, heat-conductive silicone grease, etc. In some embodiments, the thickness (in the first direction Z) of the first heat dissipation material layer 420 ranges from 1 μm to 500 μm. The first heat dissipation material layer 420 can have an adhesive force and can be used to fix adjacent winding cores in the same winding core group. The first heat dissipation material layer 420 can improve heat dissipation while also improving the attachment strength between winding cores.

[0043] More specifically, referring to the first winding core group 310 in FIG. 1A-1 The first winding core 210 further includes an end-closing adhesive 219, which can be used to fix the end-closing end 204e of the separator 204 of the first winding core 210 (see FIG. 2). Similarly, the second jelly-roll 230 also includes a tailing adhesive 239, which can be used to fix the tailing end of the separator of the second jelly-roll 230. The tailing adhesive 219 and the tailing adhesive 239 can be located between the first jelly-roll 210 and the second jelly-roll 230 and are spaced apart in the second direction X. The first heat dissipation material layer 420 can be located between the tailing adhesive 219 and the tailing adhesive 239 in the second direction X. The tailing adhesive 219 and the tailing adhesive 239 are spaced apart in the second direction X, which can reduce the thickness of the battery compared to the manner in which the tailing adhesives are stacked. In addition, the tailing adhesive 219 and the tailing adhesive 239 cause the first jelly-roll 210 and the second jelly-roll 230 to have a gap therebetween, which is conducive to electrolyte infiltration and liquid retention.

[0044] Reference is made to FIG. 1A-1 As shown in the cross section defined by the first direction Z and the second direction X, the insulating tape 150 surrounds the first jelly-roll group 310 and the second jelly-roll group 320. In this way, the insulating tape 150 can increase the tightening effect on the corner sections of the jelly-rolls, so that the pole pieces at the corner sections are better tightly fitted, which can further improve the lithium precipitation phenomenon.

[0045] Reference is made to FIG. 1A-2 As shown in the first jelly-roll group 310, one end 1811 of the first sub-tightening tape 181A extends to the flat section 212 (which can be referred to as the first flat section) via the first corner section 216 of the first jelly-roll 210, one end 1813 of the second sub-tightening tape 181B extends to the flat section 212 via the second corner section 218 of the first jelly-roll 210, and the one end 1811 of the first sub-tightening tape 181A and the one end 1813 of the second sub-tightening tape 181B are spaced apart in the second direction X on the flat section 212. By extending the first sub-tightening tape 181A and the second sub-tightening tape 181B to the flat section 212, the area covered by the tightening tape on the first jelly-roll 210 can be increased, thereby achieving a better fixing effect.

[0046] The other end 1812 of the first sub-tightening tape 181A extends to the flat section 234 (which can be referred to as the second flat section) via the first corner section 236 of the second jelly-roll 230, the other end 1814 of the second sub-tightening tape 181B extends to the flat section 234 via the second corner section 238 of the second jelly-roll 230, and the other end 1812 of the first sub-tightening tape 181A and the other end 1814 of the second sub-tightening tape 181B are spaced apart in the second direction X. By extending the first sub-tightening tape 181A and the second sub-tightening tape 181B to the flat section 234, the area covered by the tightening tape on the second jelly-roll 230 can be increased, thereby achieving a better fixing effect.

[0047] Reference is made to FIG. 1A-1 to FIG. 1E and in combination with FIG. 2As shown, the first jellyroll 210, 220 and the second jellyroll 230, 240 also respectively include positive electrode tabs 203 and negative electrode tabs 205 protruding in the third direction Y. In the first jellyroll group 310, the positive electrode tabs 203 of the first jellyroll 210 and the second jellyroll 230 are adjacently arranged along the first direction Z, and the negative electrode tabs 205 of the first jellyroll 210 and the second jellyroll 230 are adjacently arranged along the first direction Z. The structure configuration of the first jellyroll 220 and the second jellyroll 240 in the second jellyroll group 320 and the first heat dissipation material layer 420 is similar to the first jellyroll group 310, and thus will not be described again.

[0048] Reference FIG. 1B and FIG. 1C As shown, the secondary battery 100A can also include a top cover plate 118 and electrode terminals 119, the top cover plate 118 can be used to close the opening of the casing 110. The number of electrode terminals 119 can be two, which are positive electrode terminals and negative electrode terminals respectively. The electrode terminals 119 are fixed to the top cover plate 118 and electrically connected to the corresponding positive electrode tabs 203 and negative electrode tabs 205 of each jellyroll.

[0049] In the assembly of the secondary battery of the utility model, the first jellyroll 210 and the second jellyroll 230 can be stacked and fixed by using the tightening belt 181 first, and then the positive electrode tabs 203 and the negative electrode tabs 205 of the first jellyroll 210 and the second jellyroll 230 are gathered and fixed to form the first jellyroll group 310. And the second jellyroll group 320 is formed in a similar way. Then, the gathered positive electrode tabs 203 and negative electrode tabs 205 of the first jellyroll group 310 and the second jellyroll group 320 are connected to the corresponding electrode terminals 119 through the connecting sheets by welding. Then, the positive electrode tabs 203 and the negative electrode tabs 205 can be bent so that the first jellyroll group 310 and the second jellyroll group 320 are stacked with each other, and then the stacked first jellyroll group 310 and the second jellyroll group 320 are placed in the casing 110, and the top cover plate 118 is fixed with the casing 110.

[0050] FIG. 3 is a cross-sectional schematic view of a secondary battery 100B according to another embodiment of the present application. FIG. 3 The secondary battery 100B shown can be similar to the secondary battery 100A described above with respect to FIG. 1A-1 to FIG. 2 The following only describes the differences of the secondary battery 100B. Reference FIG. 3As shown, the secondary battery 100B can further include a second heat dissipation material layer 440 located between the adjacent first jelly-roll group 310 and the second jelly-roll group 320 along the first direction Z. Since the interface between the first jelly-roll group 310 and the second jelly-roll group 320 is located inside the shell 110, there is a problem of poor heat dissipation at this location. By arranging the second heat dissipation material layer 440 between the adjacent jelly-roll groups, the heat dissipation at the location between the adjacent jelly-roll groups can be improved.

[0051] In some embodiments, the heat dissipation material of the second heat dissipation material layer 440 is any one or more of aerogel, heat-conductive adhesive tape, heat-conductive rubber, heat-conductive sheet, heat-conductive pad, heat-conductive silicone grease, etc. In some embodiments, the thickness of the second heat dissipation material layer 440 ranges from 1 μm to 500 μm. The second heat dissipation material layer 440 can have adhesive force and can be used to fix the adjacent first jelly-roll group 310 and the second jelly-roll group 320, thereby improving the heat dissipation effect while also improving the bonding strength between the jelly-roll groups.

[0052] FIG. 4A and FIG. 4B are respectively a front view schematic diagram of a secondary battery 100C according to another embodiment of the present application. FIG. 4C and FIG. 4D are respectively a top view schematic diagram and a bottom view schematic diagram of the secondary battery 100C according to another embodiment of the present application. FIG. 4A to FIG. 4D The secondary battery 100C shown can be similar to the secondary battery 100A, 100B described above in many aspects, and only the differences of the secondary battery 100C are described below. FIG. 1A-1 to FIG. 3

[0053] Reference is made to FIG. 4A to FIG. 4D FIG. 1A-1 to FIG. 3 As shown, the insulating tape 150 can include a plurality of sub-insulating tapes, and two sub-insulating tapes 150A, 150B are shown as an example in the present embodiment. Each of the sub-insulating tapes 150A, 150B can have a width W1’. The widths W1’ of the sub-insulating tapes 150A, 150B can be the same, or can also be different. The sum of the widths W1’ of the sub-insulating tapes 150A, 150B and the width W2 of the tightening tape 181 can be 60%-90% of the width W3. The sum of the widths W1’ of the sub-insulating tapes 150A, 150B and the width W4 of the tightening tape 182 can be 60%-90% of the width W3. By arranging a plurality of sub-insulating tapes 150A, 150B to collectively form the insulating tape 150, the width of each sub-insulating tape can be reduced, which reduces the process difficulty of arranging a single wider insulating tape 150 on a plurality of jelly-rolls, and also ensures the coverage area of the insulating tape 150.

[0054] ​In the third direction Y, the tightening bands 181, 182 can be arranged between and spaced apart from the two sub-insulating bands 150A, 150B. By arranging the tightening bands 181, 182 between the two sub-insulating bands, a more uniform tightening effect can be provided on the corner sections of the jelly-roll, which is conducive to improving the lithium precipitation phenomenon.

[0055] In summary, the technical solutions of the present application use the insulating bands of various embodiments to cover the corner sections of the jelly-roll, increase the tightening effect on the corner sections of the jelly-roll, make the corner sections of the jelly-roll better tightly fit, and improve the lithium precipitation phenomenon. In addition, the fixing effect on each jelly-roll can be strengthened, the structural stability of the jelly-rolls can be strengthened, and the overall processing and manufacturing of the prismatic battery can be facilitated. In addition, by arranging the tightening bands in the jelly-roll group, the tightening effect on the corner sections of the jelly-rolls in the jelly-roll group can be increased to improve the lithium precipitation phenomenon and strengthen the fixing effect on the jelly-rolls in the jelly-roll group, thereby strengthening the structural stability. In addition, the first heat dissipation material layer can be arranged between adjacent jelly-rolls in the jelly-roll group to improve the heat dissipation and fitting strength of the positions between the adjacent jelly-rolls in the jelly-roll group. By arranging the second heat dissipation material layer between adjacent jelly-roll groups, the heat dissipation and fitting strength of the positions between the adjacent jelly-roll groups can be improved.

[0056] It should be understood that various features of the embodiments of the present application can be replaced, combined, or modified. The above is only a preferred embodiment of the present application and is not intended to limit the present application. Any combination of the embodiments, any modification, equivalent replacement, improvement, etc. of the embodiments within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A secondary battery characterized by comprising: The secondary battery comprises: a housing; at least two core groups accommodated in the housing and arranged in a stack along a first direction, each of the core groups comprising at least two cores arranged in a stack along the first direction, an outer circumferential surface of each of the cores comprising two flat segments arranged oppositely along the first direction, and a first corner segment and a second corner segment connecting the two flat segments and respectively located at opposite sides of the core along a second direction perpendicular to the first direction; and an insulation tape covering at least a portion of the first corner segment and at least a portion of the second corner segment of each of the cores in the at least two core groups.

2. The secondary battery of claim 1, wherein each of the cores is formed by winding a positive electrode sheet, a negative electrode sheet, and a separator between the positive electrode sheet and the negative electrode sheet, the insulation tape, the tightening tape, and the separator each have a width in the third direction, a sum of the width of the insulation tape and the width of the tightening tape is 60%-90% of the width of the separator of any of the cores.

3. The secondary battery of claim 1, wherein the insulation tape comprises a plurality of sub-insulation tapes arranged in the third direction.

4. The secondary battery of claim 3, wherein the tightening tape is arranged between and spaced apart from two sub-insulation tapes in the third direction.

5. The secondary battery of claim 1, wherein in a cross section defined by the first direction and the second direction, the insulation tape surrounds the at least two core groups.

6. The secondary battery of claim 1, wherein the tightening tape comprises a first sub-tightening tape and a second sub-tightening tape, the first sub-tightening tape covers at least a portion of the first corner segment of each of the cores in the core group, and the second sub-tightening tape covers at least a portion of the second corner segment of each of the cores in the core group.

7. The secondary battery of claim 6, wherein the housing comprises a first wall and a second wall arranged oppositely along the first direction, the core in the core group adjacent to the first wall along the first direction is a first core, and the core adjacent to the second wall along the first direction is a second core, the flat segment of the first core adjacent to the first wall is a first flat segment, ​ ​ One end of the first sub-belt tight band extends onto the first flat section via the first corner section of the first winding core, one end of the second sub-belt tight band extends onto the first flat section via the second corner section of the first winding core, and the one end of the first sub-belt tight band and the one end of the second sub-belt tight band are spaced apart along the second direction.

8. The secondary battery of claim 7, wherein, The flat section of the second winding core adjacent to the second wall is a second flat section, The other end of the first sub-belt tight band extends onto the second flat section via the first corner section of the second winding core, the other end of the second sub-belt tight band extends onto the second flat section via the second corner section of the second winding core, and the other end of the first sub-belt tight band and the other end of the second sub-belt tight band are spaced apart along the second direction.

9. The secondary battery according to claim 1, characterized by Further comprising: A first heat dissipation material layer between two adjacent winding cores in each of the winding core groups along the first direction.

10. The secondary battery according to claim 9, characterized by Further comprising: A second heat dissipation material layer between two adjacent winding core groups in the at least two winding core groups along the first direction. Further comprising: A first heat dissipation material layer between two adjacent winding cores in each of the winding core groups along the first direction. Further comprising: A second heat dissipation material layer between two adjacent winding core groups in the at least two winding core groups along the first direction.

Images