Secondary battery

Abstract

Some embodiments of the utility model provide a secondary battery, the secondary battery comprises a shell, a plurality of roll cores stacked in the shell along a first direction, a first insulating tape and a second insulating tape, the shell comprises a first wall and a second wall which are oppositely arranged along the first direction; the peripheral surface of each roll core comprises two straight sections which are oppositely arranged along the first direction, and a first corner section and a second corner section which are connected with the two straight sections, the roll core which is adjacent to the first wall along the first direction in the plurality of roll cores is a first roll core, and the roll core which is adjacent to the second wall is a second roll core; the first insulating tape covers at least one part of the first corner section of the first roll core and at least one part of the first corner section of the second roll core; the second insulating tape covers at least a portion of the second corner section of the first winding core and at least a portion of the second corner section of the second winding core. 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 includes: a shell including a first wall and a second wall oppositely arranged along a first direction; a plurality of winding cores stacked in the shell along the first direction, an outer peripheral surface of each winding core including 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 perpendicular to the first direction, wherein a winding core adjacent to the first wall along the first direction among the plurality of winding cores is a first winding core, and a winding core adjacent to the second wall along the first direction is a second winding core; a first insulating tape covering at least a portion of the first corner section of the first winding core and at least a portion of the first corner section of the second winding core; and a second insulating tape covering at least a portion of the second corner section of the first winding core and at least a portion of the second corner section of the second winding core.

[0005] In some embodiments, each winding core is formed by winding a positive electrode tab, a negative electrode tab, and a separator between the positive electrode tab and the negative electrode tab, the first insulating tape, the second insulating tape, and the separator each having a width in a third direction perpendicular to the first direction and the second direction, and the width of any one of the first insulating tape and the second insulating tape is 60%-90% of the width of the separator of any one of the plurality of winding cores.

[0006] In some embodiments, among the two flat sections of the first winding core, the flat section adjacent to the first wall is a first flat section, and among the two flat sections of the second winding core, the flat section adjacent to the second wall is a second flat section; one end of the first insulating tape extends to the first flat section via a portion of the first corner section of the first winding core, and the other end of the first insulating tape extends to the second flat section via a portion of the first corner section of the second winding core.

[0007] In some embodiments, one end of the second insulation tape extends onto the first flat section via a portion of the second corner section of the first winding core, and the other end of the second insulation tape extends onto the second flat section via a portion of the second corner section of the second winding core.

[0008] In some embodiments, the first insulation tape and the second insulation tape do not overlap in the first direction.

[0009] In some embodiments, the flat section adjacent to the first wall among the two flat sections of the first winding core is the first flat section, the flat section adjacent to the second wall among the two flat sections of the second winding core is the second flat section, one end of the first insulation tape is located at the junction of the first corner section and the first flat section of the first winding core, and the other end of the first insulation tape is located at the junction of the first corner section and the second flat section of the second winding core.

[0010] In some embodiments, the plurality of winding cores are divided into at least two winding core groups, each winding core group includes at least two winding cores and a tightening tape, the tightening tape covers 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, and the tightening tape is arranged spaced apart from the first insulation tape and the second insulation tape in a third direction, the third direction being perpendicular to the first direction and the second direction.

[0011] In some embodiments, the secondary battery further includes: a first heat dissipation material layer located between adjacent two winding cores in each winding core group in the first direction.

[0012] In some embodiments, the secondary battery further includes: a second heat dissipation material layer located between adjacent two winding core groups in the at least two winding core groups in the first direction.

[0013] In some embodiments, the first insulation tape includes a plurality of sub-insulation tapes, and the plurality of sub-insulation tapes are arranged spaced apart in a third direction, the third direction being perpendicular to the first direction and the second direction.

[0014] The above technical solutions of the present application cover the corner sections of the winding cores by using the first insulation tape and the second insulation tape of various embodiments, increase the tightening effect on the corner sections of the winding cores, make the pole pieces at the corner sections fit more closely, and can improve the lithium precipitation phenomenon. In addition, the fixing effect on each winding core can be strengthened, the structural stability of the plurality of winding cores can be strengthened, and the overall processing and manufacturing of the prismatic battery can also be facilitated. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the field, other drawings can be obtained based on these drawings without creative effort. 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 is a cross-sectional view of a secondary battery according to an embodiment of the present application.

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

[0018] FIG. 1C is FIG. 1A is a top view of the jelly-roll of the secondary battery in FIG. 1 at a cross-section C-C.

[0019] FIG. 2 is an enlarged cross-sectional view of a first jelly-roll of the secondary battery in FIG. 1.

[0020] FIG. 3 is a cross-sectional view of a secondary battery according to another embodiment of the present application.

[0021] FIG. 4A is a cross-sectional view of a secondary battery according to another embodiment of the present application.

[0022] FIG. 4B is a front view of the jelly-roll of the secondary battery in FIG. 1 at a cross-section B-B. FIG. 4A

[0023] is a top view of the jelly-roll of the secondary battery in FIG. 1 at a cross-section C-C. FIG. 4C FIG. 4A is a top view of a secondary battery according to another embodiment of the present application.

[0024] FIG. 5 is a cross-sectional view of a secondary battery according to another embodiment of the present application.

[0025] FIG. 6A is a front view of the jelly-roll of the secondary battery in FIG. 1 at a cross-section B-B.

[0026] FIG. 6B FIG. 6A is a front view of the jelly-roll of the secondary battery in FIG. 1 at a cross-section B-B.

[0027] FIG. 6C is a top view of the jelly-roll of the secondary battery in FIG. 1 at a cross-section C-C. FIG. 6A ​​A front view schematic diagram of the winding core of the secondary battery in FIG. 1 at the section B-B opposite side.

[0028] FIG. 6D is FIG. 6A A top view schematic diagram of the winding core of the secondary battery in FIG. 1 at the section C-C.

[0029] FIG. 6E is FIG. 6A A bottom view schematic diagram of the winding core of the secondary battery in FIG. 1 at the section C-C opposite side DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art belong to the scope of protection of the present application.

[0031] The following disclosure provides many different embodiments, or examples, for implementing different characteristics 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 indicate the relationship between the various embodiments and / or arrangements discussed.

[0032] 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 describing a specific figure, other structures not described in the figure can be set according to actual needs, and are not intended to limit the present application.

[0033] For a secondary battery including a plurality of winding cores (for example, at least 4 winding cores), since the corner regions of the winding cores are not subjected to heat pressing treatment, the contact between the pole pieces and the separators of the winding cores in the corner regions is loose and the gap is large, and the phenomenon of lithium precipitation on the surface of the negative pole piece in the corner region 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 region.

[0034] Embodiments of the present application provide a secondary battery. FIG. 1Ais a cross-sectional schematic view of a secondary battery 100A according to an embodiment of the present application. Referring to FIG. 1A As shown, the secondary battery 100A can include a housing 110 including a first wall 112 and a second wall 114 oppositely arranged along a first direction Z. The secondary battery 100A can also include a plurality of jelly rolls, in FIG. 1A The plurality of jelly rolls includes first to fourth jelly rolls 210, 220, 230 and 240 as an example, and in other embodiments, a greater or smaller number of jelly rolls can also be employed. The first to fourth jelly rolls 210, 220, 230 and 240 are arranged in a stack within the housing 110 along the first direction Z. Among them, the first jelly roll 210 is adjacent to the first wall 112 along the first direction Z, and the second jelly roll 220 is adjacent to the second wall 114. The third jelly roll 230 and the fourth jelly roll 240 are stacked between the first jelly roll 210 and the fourth jelly roll 240, the third jelly roll 230 is adjacent to the first jelly roll 210, and the fourth jelly roll 240 is adjacent to the second jelly roll 220.

[0035] The structures of the first to fourth jelly rolls 210, 220, 230 and 240 can be similar, and the structure of the jelly roll will be described below with reference to FIG. 2 the first jelly roll 210. FIG. 2 An enlarged cross-sectional schematic view of the first jelly roll 210 is shown. Referring to FIG. 2 As shown, the first jelly roll 210 can be formed by winding a positive electrode tab 201, a negative electrode tab 202 and a separator 204 between the positive electrode tab 201 and the negative electrode tab 202. In some embodiments, the secondary battery is a prismatic battery, and the first jelly roll 210 formed by winding has a flat rectangular shape. In some embodiments, the first direction Z is the thickness direction of the first jelly roll 210.

[0036] The outer peripheral surface of the first jelly roll 210 is formed by the separator 204. The outer peripheral surface of the first jelly roll 210 includes two flat sections 212, 214 oppositely arranged 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 are located on opposite sides of the first jelly roll 210 along a second direction X, respectively, and the second direction X is perpendicular to the first direction Z.

[0037] Referring back to FIG. 1ASimilar to the first jelly-roll 210, the outer circumferential surface of the second jelly-roll 220 includes two flat sections 222, 224 oppositely arranged along the first direction Z, and a first corner section 226 and a second corner section 228 connecting the two flat sections 222, 224, the first corner section 226 and the second corner section 228 being respectively located at opposite sides of the second jelly-roll 220 along the second direction X. The outer circumferential surface of the third jelly-roll 230 includes two flat sections (not numbered) oppositely arranged along the first direction Z, and a first corner section 236 and a second corner section 238 connecting the two flat sections. The outer circumferential surface of the fourth jelly-roll 240 includes two flat sections (not numbered) oppositely arranged along the first direction Z, and a first corner section 246 and a second corner section 248 connecting the two flat sections.

[0038] The secondary battery 100A can further include a first insulating tape 152 and a second insulating tape 154. The first insulating tape 152 covers at least a portion of the first corner section 216 of the first jelly-roll 210 and at least a portion of the first corner section 226 of the second jelly-roll 220. The second insulating tape 154 covers at least a portion of the second corner section 218 of the first jelly-roll 210 and at least a portion of the second corner section 228 of the second jelly-roll 220. In the present embodiment, the first insulating tape 152 also covers at least a portion of the first corner section 236 of the third jelly-roll 230 and at least a portion of the first corner section 246 of the fourth jelly-roll 240. The second insulating tape 154 also covers at least a portion of the second corner section 238 of the third jelly-roll 230 and at least a portion of the second corner section 248 of the fourth jelly-roll 240. In some embodiments, the first insulating tape 152 and the second insulating tape 154 can respectively include a substrate and an adhesive layer, and the first insulating tape 152 and the second insulating tape 154 can be adhered to the surface of the jelly-rolls by the adhesive layers.

[0039] In the above technical solution, by adopting the first insulating tape 152 and the second insulating tape 154 to cover the corner sections of the jelly-rolls, the tightening effect of the corner sections of the jelly-rolls is increased, so that the pole pieces at the corner sections are better tightly fitted, and the lithium precipitation phenomenon can be improved. In addition, the fixing effect on the jelly-rolls can be further strengthened, and the structural stability of the jelly-rolls is strengthened. Moreover, the process difficulty of setting the first insulating tape 152 and the second insulating tape 154 is low, and the overall processing and manufacturing of the prismatic battery are facilitated.

[0040] In some embodiments, the thickness (along the first direction Z) of the first insulating tape 152 and the second insulating tape 154 ranges from 20 μm to 40 μm, respectively. In some embodiments, the first insulating tape 152 and the second insulating tape 154 each comprise an adhesive layer having adhesive strength. In some embodiments, as described above, the first insulating tape 152 and the second insulating tape 154 each comprise a base and an adhesive layer, wherein the adhesive layer has a thickness ranging from 5 μm to 20 μm, for example. In some embodiments, the adhesive layer has an adhesive strength ranging from 1 N / cm to 10 N / cm.

[0041] Continue to refer FIG. 1A As shown, the straight section 212 of the first winding core 210 (which may be referred to as the first straight section) is adjacent to the first wall 112 of the housing 110, and the straight section 224 of the second winding core 220 (which may be referred to as the second straight section) is adjacent to the second wall 114. In this embodiment, one end 152a of the first insulating tape 152 is located at the intersection of the first corner section 216 of the first winding core 210 and the straight section 212 (as indicated by the dashed line L1), and the other end 152b of the first insulating tape 152 is located at the intersection of the first corner section 226 and the straight section 224 of the second winding core 220 (as indicated by the dashed line L1). By positioning one end 152a and the other end 152b of the first insulating tape 152 at the intersection of the corresponding first corner sections 216 and 226 with the planar sections 212 and 224, respectively, the coverage area of ​​the first insulating tape 152 on the first corner sections 216 and 226 can be increased, thereby strengthening the fixing effect on each winding core.

[0042] One end 154a of the second insulating tape 154 is located at the intersection of the second corner section 218 and the straight section 212 of the first winding core 210 (as indicated by the dashed line L2), and the other end 154b of the second insulating tape 154 is located at the intersection of the second corner section 228 and the straight section 224 of the second winding core 220 (as indicated by the dashed line L2). By positioning one end 154a and the other end 154b of the second insulating tape 154 at the intersections of the corresponding second corner sections 218, 228 with the flat sections 212, 224, respectively, the coverage area of ​​the second insulating tape 154 on the second corner sections 218, 228 can be increased, thereby strengthening the fixing effect on each winding core.

[0043] FIG. 1B yes FIG. 1A Schematic front view of the winding core of the secondary battery 100A at section BB. FIG. 1C yes FIG. 1A A schematic top view of the winding core of the secondary battery 100A at section CC. For clarity, FIG. 1B and FIG. 1C The housing 110 is not shown. FIGS. 1A-1CAs shown, the first insulation tape 152 and the second insulation tape 154 have widths W1, W2 in the third direction Y. The third direction Y is perpendicular to the first direction Z and the second direction X. The separator 204 in the first to fourth jelly rolls 210-240 has a width W3 in the third direction Y. In some embodiments, the width W1 of the first insulation tape 152 is 60%-90% of the width W3 of the separator 204 of any one of the first to fourth jelly rolls 210-240. In some embodiments, the width W2 of the second insulation tape 154 is 60%-90% of the width W3 of the separator 204 of any one of the first to fourth jelly rolls 210-240. Through the above width configuration of the first and second insulation tapes 152, 154, the first and second insulation tapes 152, 154 can be attached and covered on the corresponding corner sections in a large area, and the first and second insulation tapes 152, 154 can better tighten the corner sections, so that the pole pieces at the corner sections are better tightly attached, to improve the lithium precipitation phenomenon.

[0044] Reference FIG. 1A In some embodiments, the first to fourth jelly rolls 210-240 are divided into two jelly roll groups. Specifically, the first jelly roll 210 and the third jelly roll 230 can constitute a first jelly roll group 310, and the second jelly roll 220 and the fourth jelly roll 240 can constitute a second jelly roll group 320. In other embodiments, the number of jelly rolls in a jelly roll group can also include more than two. In some embodiments, the secondary battery 100A can further include a first heat dissipation material layer 420, which is arranged between the first jelly roll 210 and the third jelly roll 230, and between the second jelly roll 220 and the fourth jelly roll 240, along the first direction Z. For a secondary battery including a plurality of jelly rolls, the heat dissipation between adjacent jelly rolls in a jelly roll group is difficult, and by arranging the first heat dissipation material layer 420 between adjacent jelly rolls in a jelly roll group, the heat dissipation between adjacent jelly rolls in a jelly roll group can be improved.

[0045] 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 (along 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 adhesion and can be used to fix adjacent jelly rolls in the same jelly roll group. The first heat dissipation material layer 420 can improve the heat dissipation effect while also improving the attachment strength between the jelly rolls. Since the first heat dissipation material layer 420 is used to attach adjacent jelly rolls in a jelly roll group, the use of tightening tapes in the jelly roll group can be saved.

[0046] More specifically, with reference to FIG. 1AThe first core group 310 in the first core 210 further includes a tail glue 219, which can be used to fix the tail end 204e of the diaphragm 204 of the first core 210 (see FIG. 2 ). Similarly, the third winding core 230 also includes a closing glue 239, which can be used to fix the closing end of the diaphragm of the third winding core 230. The closing glue 219 and the closing glue 239 can be located between the first winding core 210 and the third winding core 230, and are spaced apart in the second direction X. The first heat dissipation material layer 420 can be located between the closing glue 219 and the closing glue 239. The closing glue 219 and the closing glue 239 are spaced apart in the second direction X, which can reduce the thickness of the battery compared to the stacking arrangement of the closing glue. In addition, the closing glue 219 and the closing glue 239 create a gap between the first winding core 210 and the third winding core 230, which is conducive to electrolyte infiltration and liquid retention.

[0047] refer to FIGS. 1A-1C Combined with FIG. 2 As shown, the first to fourth cores 210 to 240 also include positive electrode tabs 203 and negative electrode tabs 205, respectively, protruding in the third direction Y. In the first core group 310, the positive electrode tabs 203 of the first and third cores 210 and 230 are arranged adjacent to each other along the first direction Z, and the negative electrode tabs 205 of the first and third cores 210 and 230 are arranged adjacent to each other along the first direction Z. The structural configurations of the second and fourth cores 220, 240, and the first heat dissipation material layer 420 in the second core group 320 are similar to those of the first core group 310, and therefore will not be repeated.

[0048] refer to FIG. 1B As shown, the secondary battery 100A may further include a top cover plate 118 and electrode terminals 119. The top cover plate 118 may be used to seal the opening of the housing 110. There may be two electrode terminals 119, one for the positive electrode and one for the negative electrode. The electrode terminals 119 are fixed to the top cover plate 118 and electrically connected to the corresponding positive and negative electrode tabs 203 and 205 of each winding core.

[0049] In assembling the secondary battery of the present application, the first jelly-roll 210 and the third jelly-roll 230 can be first stacked and fixed (in the present embodiment, fixed by the first heat dissipation material layer 420), and then the positive electrode tabs 203 and the negative electrode tabs 205 of the first jelly-roll 210 and the third jelly-roll 230 are gathered and fixed to form the first jelly-roll group 310. In a similar manner, the second jelly-roll group 320 is formed. Then, the gathered positive electrode tabs 203 and the negative electrode tabs 205 of the first jelly-roll group 310 and the second jelly-roll group 320 are connected to the corresponding electrode terminals 119 via the connecting tabs by welding. Then, the positive electrode tabs 203 and the negative electrode tabs 205 can be bent so that the first jelly-roll group 310 and the second jelly-roll group 320 are stacked on each other, and the stacked first jelly-roll group 310 and the second jelly-roll group 320 are placed in the case 110, and the top cover plate 118 is fixed to the case 110.

[0050] FIG. 3 is a cross-sectional view of a secondary battery 100B according to another embodiment of the present application. FIG. 3 The secondary battery 100B shown can be similar in many respects to the secondary battery 100A described above with respect to FIGS. 1A-2 The secondary battery 100B shown can be similar in many respects to the secondary battery 100A described above with respect to FIG. 3 As 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 case 110, there is a problem of poor heat dissipation at this location. By providing 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, so that the adhesion strength between the jelly-roll groups is improved while the heat dissipation effect is improved.

[0052] FIG. 4A is a cross-sectional view of a secondary battery 100C according to another embodiment of the present application. FIG. 4B is a front view of a jelly-roll of the secondary battery 100C in FIG. 4A FIG. 4C is a front view of a jelly-roll of the secondary battery 100C in FIG. 4A is a top view of a jelly-roll of the secondary battery 100C in FIGS. 4A-4C ​As shown, one end 152a of the first insulating tape 152 can extend onto the flat section 212 via a portion of the first corner section 216 of the first winding core 210. By extending one end 152a of the first insulating tape 152 onto the flat section 212, the coverage area of the first insulating tape 152 on the first winding core 210 can be increased, and thus a better securing effect can be achieved using the first insulating tape 152.

[0053] The other end 152b of the first insulating tape 152 can extend onto the second flat section 224 via a portion of the first corner section 226 of the second winding core 220. By extending the other end 152b of the first insulating tape 152 onto the flat section 224, the coverage area of the first insulating tape 152 on the second winding core 220 can be increased, and thus a better securing effect can be further achieved using the first insulating tape 152.

[0054] One end 154a of the second insulating tape 154 can extend onto the flat section 212 via a portion of the second corner section 218 of the first winding core 210. By extending one end 154a of the second insulating tape 154 onto the flat section 212, the coverage area of the second insulating tape 154 on the first winding core 210 can be increased, and thus a better securing effect can be achieved using the second insulating tape 154.

[0055] The other end 154b of the second insulating tape 154 extends onto the flat section 224 via the second corner section 228 of the second winding core 220. By extending the other end 154b of the second insulating tape 154 onto the flat section 224, the coverage area of the second insulating tape 154 on the second winding core 220 can be increased, and thus a better securing effect can be further achieved using the second insulating tape 154.

[0056] In addition, on the flat section 212, one end 152a of the first insulating tape 152 and one end 154a of the second insulating tape 154 can be adjacent or contiguous to each other. On the flat section 224, the other end 152b of the first insulating tape 152 and the other end 154b of the second insulating tape 154 can be adjacent or contiguous to each other. That is, the first insulating tape 152 and the second insulating tape 154 do not overlap in the first direction Z to avoid an increase in thickness caused by the overlap.

[0057] FIG. 5 is a top view of a secondary battery 100D according to another embodiment of the present application. FIG. 5 The secondary battery 100D shown can be similar in many respects to the secondary battery 100A described above with respect to FIGS. 1A-2 Only the differences between the secondary battery 100D and the secondary battery 100A described above will be described below. Reference is made to the description of the secondary battery 100A above for details not described below. FIG. 5As shown, the first insulating tape 152 can include a plurality of sub-insulating tapes, three sub-insulating tapes 1521, 1522, 1523 are shown as an example in this embodiment. Each of the sub-insulating tapes 1521, 1522, 1523 can have a width W1’ respectively. The width W1’ of each of the sub-insulating tapes 1521, 1522, 1523 can be the same, or can also be different. The sum of the widths W1’ of the three sub-insulating tapes 1521, 1522, 1523 can be 60%-90% of the width W3. By setting a plurality of sub-insulating tapes 1521, 1522, 1523 to jointly form the first insulating tape 152, the width of each sub-insulating tape can be reduced, which reduces the process difficulty of setting a single wider first insulating tape 152 on a plurality of winding cores, and also ensures the coverage area of the first insulating tape 152.

[0058] The second insulating tape 154 can also include three sub-insulating tapes 1541, 1542, 1543 spaced apart along the third direction Y. Each of the sub-insulating tapes 1541, 1542, 1543 can have a width W2’ respectively. The width W2’ of each of the sub-insulating tapes 1541, 1542, 1543 can be the same, or can also be different. The sum of the widths W2’ of the three sub-insulating tapes 1541, 1542, 1543 can be 60%-90% of the width W3. By setting a plurality of sub-insulating tapes 1541, 1542, 1543 to jointly form the second insulating tape 154, the width of each sub-insulating tape can be reduced, which reduces the process difficulty of setting a single wider second insulating tape 154 on a plurality of winding cores, and also ensures the coverage area of the second insulating tape 154.

[0059] FIG. 6A is a cross-sectional schematic view of a secondary battery 100E according to another embodiment of the present application. FIG. 6B is a front view schematic view of the winding core of the secondary battery 100E in FIG. 6A FIG. 6C is a front view schematic view of the winding core of the secondary battery 100E in FIG. 6A FIG. 6D is a front view schematic view of the winding core of the secondary battery 100E in FIG. 6A FIG. 6E is a top view schematic view of the winding core of the secondary battery 100E in FIG. 6A

[0060] in combination with FIGS. 6A-6E ​​​​The secondary battery 100E can include the first and second insulating tapes 152 and 154 described above. In addition, the first jelly-roll group 310 can further include a binding tape 181. The binding tape 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 jelly-roll 210 and the third jelly-roll 230 in the first jelly-roll group 310. Specifically, in the present embodiment, the binding tape 181 includes sub-binding tapes 181A, 181B. The sub-binding tape 181A covers at least a portion of the first corner segments 216, 236 of the first jelly-roll 210 and the third jelly-roll 230, and the sub-binding tape 181B covers at least a portion of the second corner segments 218, 238 of the first jelly-roll 210 and the third jelly-roll 230.

[0061] The second jelly-roll group 320 can further include a binding tape 182. The binding tape 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 second jelly-roll 220 and the fourth jelly-roll 240 in the second jelly-roll group 320. Specifically, in the present embodiment, the binding tape 182 includes sub-binding tapes 182A, 182B. The sub-binding tape 182A covers at least a portion of the first corner segments 226, 246 of the second jelly-roll 220 and the fourth jelly-roll 240, and the sub-binding tape 182B covers at least a portion of the second corner segments 228, 248 of the second jelly-roll 220 and the fourth jelly-roll 240. By respectively providing the binding tapes 181, 182 in the first jelly-roll group 310 and the second jelly-roll group 320, the binding effect on the corner segments of the jelly-rolls in the jelly-roll groups can be increased, so that the jelly-rolls are better tightly fitted at the corner segments, and the lithium precipitation phenomenon can be improved. In addition, the fixing effect on the jelly-rolls in the jelly-roll groups can also be strengthened, and the structural stability can be enhanced.

[0062] The binding tapes 181, 182 are arranged at intervals along the third direction Y from the first and second insulating tapes 152, 154. In the present embodiment, the structures of the first and second insulating tapes 152, 154 can be similar to those described above with reference to FIGS. 1A-2 The difference is that the width W1 of the first insulating tape 152 and the width W2 of the second insulating tape 154 are reduced. It should be understood that in other embodiments, the structures of the first and second insulating tapes 152, 154 can also adopt the structures described above with reference to FIG. 4A and FIG. 4B .

[0063] With reference to FIG. 6D and FIG. 6E FIG. 6DAs shown, the tightening band 181 has a width W4, and in some embodiments, the sum of the width W4 and the width W1 of the first insulating band 152 can be 60%-90% of the width W3. In some embodiments, the sum of the width W4 and the width W2 of the second insulating band 154 can be 60%-90% of the width W3. The tightening band 182 has a width W5, and in some embodiments, the sum of the width W5 and the width W2 can be 60%-90% of the width W3. In some embodiments, the sum of the width W5 and the width W1 can be 60%-90% of the width W3.

[0064] In summary, the technical scheme of the present application uses the first insulating band and the second insulating band of various embodiments to cover the corner sections of the winding cores, increases the tightening effect on the corner sections of the winding cores, makes the pole piece at the corner section more tightly fit, and can improve the lithium precipitation phenomenon. In addition, the fixing effect on each winding core can be strengthened, the structural stability of the plurality of winding cores can be strengthened, and the overall processing and manufacturing of the prismatic battery can be facilitated. In addition, the first heat dissipation material layer can be arranged between adjacent winding cores in the winding core group to improve the heat dissipation and fitting strength of the positions between the adjacent winding cores in the winding core group. The second heat dissipation material layer can be arranged between adjacent winding core groups to improve the heat dissipation and fitting strength of the positions between the adjacent winding core groups. In addition, the tightening band can be arranged in the winding core group to increase the tightening effect on the corner sections of the winding cores in the winding core group, to improve the lithium precipitation phenomenon, and to strengthen the fixing effect on the winding cores in the winding core group and the structural stability.

[0065] It should be understood that various features of the embodiments of the present application can be replaced, combined. The above is only the preferred embodiment of the present application and does not 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: Comprising: a housing including a first wall and a second wall disposed opposite each other in a first direction; a plurality of jelly rolls stacked in the housing along the first direction, each of the jelly rolls including two flat sections disposed opposite each other in 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 jelly roll in a second direction perpendicular to the first direction, wherein a jelly roll adjacent to the first wall in the first direction among the plurality of jelly rolls is a first jelly roll, and a jelly roll adjacent to the second wall in the first direction among the plurality of jelly rolls is a second jelly roll; a first insulating tape covering at least a portion of the first corner section of the first jelly roll and at least a portion of the first corner section of the second jelly roll; and a second insulating tape covering at least a portion of the second corner section of the first jelly roll and at least a portion of the second corner section of the second jelly roll. 2.The secondary battery of claim 1, wherein each of the jelly rolls is formed by winding a positive electrode tab, a negative electrode tab, and a separator between the positive electrode tab and the negative electrode tab, the first insulating tape, the second insulating tape, and the separator each have a width in a third direction perpendicular to the first direction and the second direction, the width of either of the first insulating tape and the second insulating tape is 60%-90% of the width of the separator of any of the plurality of jelly rolls. 3.The secondary battery of claim 1, wherein a flat section adjacent to the first wall among the two flat sections of the first jelly roll is a first flat section, and a flat section adjacent to the second wall among the two flat sections of the second jelly roll is a second flat section; one end of the first insulating tape extends to the first flat section via a portion of the first corner section of the first jelly roll, the other end of the first insulating tape extends to the second flat section via a portion of the first corner section of the second jelly roll. 4.The secondary battery of claim 3, wherein one end of the second insulating tape extends to the first flat section via a portion of the second corner section of the first jelly roll, the other end of the second insulating tape extends to the second flat section via a portion of the second corner section of the second jelly roll. 5.The secondary battery of claim 4, wherein the first insulating tape and the second insulating tape do not overlap in the first direction. 6.The secondary battery of claim 1, wherein a flat section adjacent to the first wall among the two flat sections of the first jelly roll is a first flat section, and a flat section adjacent to the second wall among the two flat sections of the second jelly roll is a second flat section, one end of the first insulating tape is located at an intersection of the first corner section of the first jelly roll and the first flat section, and the other end of the first insulating tape is located at an intersection of the first corner section of the second jelly roll and the second flat section. 7.The secondary battery according to claim 1, wherein the plurality of jelly rolls are divided into at least two jelly roll groups, each of the jelly roll groups including at least two of the jelly rolls and a tightening tape, 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 of the jelly rolls in the jelly roll group, the tightening tape is arranged apart from the first insulating tape and the second insulating tape in a third direction, the third direction being perpendicular to the first direction and the second direction.

8. The secondary battery according to claim 7, characterized by Further comprising: a first heat dissipation material layer between adjacent two of the jelly rolls in each of the jelly roll groups in the first direction.

9. The secondary battery according to claim 8, characterized by Further comprising: a second heat dissipation material layer between adjacent two of the jelly roll groups in the first direction. 10.The secondary battery according to claim 1, wherein the first insulating tape includes a plurality of sub-insulating tapes, the plurality of sub-insulating tapes being arranged apart in a third direction, the third direction being perpendicular to the first direction and the second direction.

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