Battery and electronic equipment

Abstract

The invention relates to the technical field of battery manufacturing, in particular to a battery and electronic equipment, a first empty foil surface and a second empty foil surface are formed at the tail part of a positive electrode current collector, an insulating layer is arranged on at least part of a straight area of the first empty foil surface, and the insulating layer extends to the edge of the positive electrode current collector. On one hand, the strength and the torsional strength of the edge part of the positive electrode current collector are improved, so that the edge of the first empty foil surface is effectively prevented from being folded; and on the other hand, even if the edge of the first empty foil surface is turned over, the insulating layer can also effectively prevent electric connection between the positive electrode current collector and the negative electrode active layer, so that the safety of the battery is improved. The bonding piece enhances the connection strength between the positive plate and the membrane shell, the probability that the first empty foil surface extrudes the inner wall surface of the membrane shell due to the vibration influence of the battery and is turned over is effectively reduced, the insulating layer and the bonding piece are not overlapped, the thickness loss caused by the overlapping of the bonding piece and the insulating layer is also avoided, the volume utilization rate of the battery is improved, and the production cost is reduced. And the overall performance and safety are improved.

Description

Technical Field

[0001] The present application relates to the field of battery manufacturing technology, and in particular to a battery and electronic equipment. Background Art

[0002] With the continuous development of new energy technologies, battery performance requirements are increasing. To improve the cycle life of battery cells, embossing is often performed on the surface of the positive electrode sheet to form a concave portion before the hot pressing process. However, after hot pressing, the probability of internal short circuits and even fires in the battery cell increases significantly, affecting battery safety and performance. Summary of the Invention

[0003] The present application provides a battery and an electronic device for improving the structural stability of the battery, thereby preventing the positive electrode foil from contacting the negative electrode active layer, and improving the performance and safety of the battery.

[0004] In order to achieve the above objectives, this application adopts the following technical solutions:

[0005] In one aspect, the present application provides a battery comprising a membrane shell and a winding core located in the membrane shell;

[0006] The winding core includes a positive electrode sheet, a separator, and a negative electrode sheet. The positive electrode sheet, the separator, and the negative electrode sheet are stacked and wound in sequence to form a flat area and arc areas on both sides of the flat area. The positive electrode sheet includes a positive electrode current collector and positive electrode active layers on both sides of the positive electrode current collector. At least a portion of the surface of the positive electrode active layer is provided with a recessed portion.

[0007] Along the winding direction, the length of the positive electrode current collector is greater than the length of the positive electrode active layer located on both sides thereof, and a first hollow foil surface and a second hollow foil surface are formed at the tail of the positive electrode current collector, the first hollow foil surface is located on the side of the positive electrode current collector away from the winding center, and at least a portion of the first hollow foil surface is located in the straight area of ​​the first to last fold of the positive electrode current collector and the straight area of ​​the second to last fold of the positive electrode current collector, wherein the straight area of ​​the first to last fold of the positive electrode current collector and the straight area of ​​the second to last fold of the positive electrode current collector are located on two opposite sides of the winding core;

[0008] The winding core also includes an adhesive and an insulating layer. The adhesive respectively bonds the tail end of the positive electrode sheet in the winding direction and the inner wall surface of the membrane shell. At least part of the insulating layer is located in the flat area of ​​the penultimate fold of the first empty foil surface. Along the width direction of the positive electrode current collector, the insulating layer extends to the edge of the positive electrode current collector, and in the orthographic projection of the winding core in the thickness direction, the insulating layer and the adhesive do not overlap with each other.

[0009] As an optional embodiment, along the width direction of the positive electrode current collector, the insulating layer covers at least a portion of the side surface of the positive electrode current collector.

[0010] As an optional embodiment, the winding core further includes a tab, and in the thickness direction of the winding core, there is a gap between the orthographic projection of the insulating layer and the orthographic projection of the tab;

[0011] The gap between the orthographic projection of the insulating layer and the orthographic projection of the tab along the width direction of the winding core is G, where G satisfies: 0.1mm≤G≤5mm.

[0012] As an optional embodiment, the insulating layer includes a first sublayer and a second sublayer, and along the width direction of the positive electrode current collector, the first sublayer extends to one side edge of the positive electrode current collector, and the second sublayer extends to the other side edge of the positive electrode current collector; and / or

[0013] The core also includes a tab and adhesive tape. Along the length direction of the core, the tab is located at one end of the core and extends away from the core. The insulating layer extends to the edge of the positive electrode current collector on the side close to the tab. The adhesive tape is located at the end of the core away from the tab. Along the thickness direction of the core, the adhesive tape covers the two opposite sides of the core. Along the width direction of the core, the ratio of the adhesive tape length to the length of the straight area is greater than 70%;

[0014] Preferably, along the width direction of the roll core, the adhesive tape extends to at least one side arc area.

[0015] As an optional embodiment, the winding core further includes a tab, and in an orthographic projection in the thickness direction of the winding core, the tab and the adhesive do not overlap with each other;

[0016] Along the winding direction, at least part of the insulating layer is located in the straight area of ​​the first to last fold and / or the straight area of ​​the third to last fold of the first empty foil surface, wherein the straight area of ​​the first to last fold of the positive electrode collector and the straight area of ​​the third to last fold of the positive electrode collector are located on the same side of the winding core.

[0017] As an optional embodiment, the insulating layer extends to the arc region on one side along the winding direction and covers at least two straight regions connected to the arc region;

[0018] The distance between the head of the insulating layer and the adjacent straight area in the thickness direction of the core is D1, and the distance between the tail of the insulating layer and the adjacent straight area in the thickness direction of the core is D2, where D1 and D2 satisfy: D1 ≥ 0.2 mm; and / or D2 ≥ 0.2 mm.

[0019] As an optional embodiment, the adhesive member is a hot melt adhesive; and / or

[0020] The insulating layer comprises at least one of ceramic, PET or PI;

[0021] Preferably, when the insulating layer is a ceramic layer, the thickness of the coated ceramic is in the range of 1um-6um;

[0022] More preferably, the ceramic layer includes at least one of boehmite, alumina, zirconium dioxide, titanium dioxide, magnesium oxide, magnesium hydroxide, silicon dioxide, and montmorillonite.

[0023] As an optional embodiment, along the winding direction, a composite area is provided between the tail of the negative electrode sheet and the separator;

[0024] The size of the composite area along the width direction of the positive electrode sheet is L, where L satisfies: L ≥ 0.05 mm; and / or

[0025] There are two composite areas, and the two composite areas are respectively located in two straight areas connected to the arc area, and there is a gap between the composite area and the adjacent arc area; and / or

[0026] The distance between the head of the composite area and the adjacent arc area is D5, and the distance between the tail of the composite area and the adjacent arc area is D6, wherein D5 and D6 satisfy: D5 ≥ 0.2 mm; and / or D6 ≥ 0.2 mm; and / or

[0027] The composite area includes at least one of overall composite, vertical line composite, pattern composite, and dot composite;

[0028] Preferably, the composite area includes vertical line composites, the interval width between the vertical lines is L1, and the vertical line width is W3, wherein L1 and W3 satisfy: 0.5mm≤L1≤3mm; and / or 30um≤W3≤300um.

[0029] As an optional embodiment, the charging cut-off voltage of the battery is ≥4.48V, the negative electrode sheet includes a negative electrode active layer, the negative electrode active layer includes a silicon-based material, and the silicon content of the silicon-based material in the negative electrode active layer is 2%-20%; and / or

[0030] The diaphragm is a melamine diaphragm.

[0031] On the other hand, the present application provides an electronic device, including a cabin and the above-mentioned battery, the battery is located in the cabin, and an adhesive layer is provided between the battery and the inner wall surface of the cabin, and the adhesive layer is located on the side of the winding core away from the adhesive part.

[0032] The battery and electronic device provided by the present application. By forming a first hollow foil surface and a second hollow foil surface at the tail of the positive electrode current collector, and providing an insulating layer in at least a partially flat area of ​​the first hollow foil surface, the insulating layer extends to the edge of the positive electrode current collector. The provision of the insulating layer, on the one hand, increases the strength and torsional strength of the edge portion of the positive electrode current collector, thereby effectively avoiding the occurrence of the edge folding phenomenon of the first hollow foil surface; on the other hand, even if the edge of the first hollow foil surface folds, the insulating layer can effectively prevent the electrical connection between the positive electrode current collector and the negative electrode active layer, thereby significantly reducing the risk of short circuit of the battery cell and improving the safety of the battery. The design of the adhesive enhances the connection strength between the positive electrode sheet and the membrane shell, thereby effectively reducing the probability of the first hollow foil surface being squeezed against the inner wall surface of the membrane shell by the vibration of the battery and folding, and the insulating layer and the adhesive do not overlap with each other, and also avoid the thickness loss caused by the overlap of the adhesive and the insulating layer, thereby improving the volume utilization of the battery and improving the overall performance and safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0034] Figure 1 This is one of the structural schematic diagrams of the winding core provided in an embodiment of the present application;

[0035] Figure 2 for Figure 1 A schematic structural diagram of the positive electrode sheet of the winding core shown;

[0036] Figure 3 This is the second structural diagram of the winding core provided in the embodiment of the present application;

[0037] Figure 4 for Figure 3 A schematic structural diagram of the positive electrode sheet of the winding core shown;

[0038] Figure 5 The third structural diagram of the winding core provided in the embodiment of the present application;

[0039] Figure 6 This is the fourth structural diagram of the winding core provided in the embodiment of the present application;

[0040] Figure 7 A schematic structural diagram of the positive electrode sheet of the winding core provided in an embodiment of the present application;

[0041] Figure 8 This is a schematic diagram of the structure of the stacked positive electrode sheet, separator and negative electrode sheet of the winding core provided in an embodiment of the present application;

[0042] Figure 9 This is a second schematic diagram of the stacked structure of the positive electrode sheet, separator, and negative electrode sheet of the winding core provided in an embodiment of the present application;

[0043] Figure 10 This is one of the structural diagrams of the electronic device provided in the embodiment of the present application;

[0044] Figure 11 This is the second structural diagram of the electronic device provided in an embodiment of the present application.

[0045] Description of reference numerals:

[0046] 100-battery; 101-membrane shell; 102-winding core; 103-flat area; 104-arc area; 105-composite area; 10-positive electrode sheet; 11-positive electrode current collector; 12-positive electrode active layer; 121-recessed portion; 13-first empty foil surface; 20-diaphragm; 30-negative electrode sheet; 40-adhesive; 50-insulating layer; 51-first sublayer; 52-second sublayer; 60-ear; 70-tape; 200-electronic equipment; 201-cabin; 202-adhesive layer. DETAILED DESCRIPTION

[0047] To make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0048] With the continuous development of new energy technologies, the performance requirements for batteries are increasing day by day. In order to improve the cycle life of battery cells, the positive electrode sheets of battery cells are usually embossed before the hot pressing process.

[0049] However, after hot pressing and forming, some of the concave parts formed by embossing are squeezed, resulting in thinner thickness of the electrode, which in turn increases the movable space, i.e. the gap, between the winding core and the membrane shell, and makes the pre-tightening force of the battery cell after forming much lower than the pre-tightening force after winding. Moreover, since the membrane shell is usually an aluminum-plastic film and the innermost layer is a flexible PP layer, there is a possibility of forming corners and embossing on the inner wall of the membrane shell and the top / bottom edge of the corresponding battery cell.

[0050] Under the influence of external forces such as drop impact, the top edge / bottom edge of the empty foil in the single-sided area of ​​the positive electrode on the outermost adhesive surface of the battery cell (i.e., the edge of the first empty foil surface in the embodiment of the present application) impacts the folding angle and embossing of the inner wall of the membrane shell, which may cause part of the empty foil roll core to fold over on the inside, so that the burrs on the top / bottom edge of the positive electrode may puncture the diaphragm and contact the negative electrode active layer, thereby causing the battery cell to short circuit or even fire, affecting the safety and performance of the battery.

[0051] In order to overcome the defects in the existing technology, after repeated thinking and verification, the inventors found that if insulating material is provided at the edge of the positive electrode single-sided area, on the one hand, the strength and torsional strength of the edge part of the positive electrode single-sided area can be increased, effectively avoiding folding. On the other hand, it can also avoid electrical connection between the positive electrode foil and the negative electrode active layer after folding, thereby improving safety.

[0052] In view of this, the present application provides a battery, comprising a membrane shell and a winding core located in the membrane shell;

[0053] The winding core includes a positive electrode sheet, a separator, and a negative electrode sheet. The positive electrode sheet, the separator, and the negative electrode sheet are stacked and wound in sequence to form a flat area and arc areas on both sides of the flat area. The positive electrode sheet includes a positive electrode current collector and positive electrode active layers on both sides of the positive electrode current collector. At least a portion of the surface of the positive electrode active layer is provided with a recessed portion.

[0054] Along the winding direction, the length of the positive electrode current collector is greater than the length of the positive electrode active layer located on both sides thereof, and a first hollow foil surface and a second hollow foil surface are formed at the tail of the positive electrode current collector, the first hollow foil surface is located on the side of the positive electrode current collector away from the winding center, and at least a portion of the first hollow foil surface is located in the straight area of ​​the first to last fold of the positive electrode current collector and the straight area of ​​the second to last fold of the positive electrode current collector, wherein the straight area of ​​the first to last fold of the positive electrode current collector and the straight area of ​​the second to last fold of the positive electrode current collector are located on two opposite sides of the winding core;

[0055] The winding core also includes an adhesive and an insulating layer. The adhesive respectively bonds the tail end of the positive electrode sheet in the winding direction and the inner wall surface of the membrane shell. At least part of the insulating layer is located in the flat area of ​​the penultimate fold of the first empty foil surface. Along the width direction of the positive electrode current collector, the insulating layer extends to the edge of the positive electrode current collector, and in the orthographic projection of the winding core in the thickness direction, the insulating layer and the adhesive do not overlap with each other.

[0056] By forming a first hollow foil surface and a second hollow foil surface at the tail of the positive electrode current collector, and providing an insulating layer on at least a portion of the flat area of ​​the first hollow foil surface, the insulating layer extends to the edge of the positive electrode current collector. The provision of the insulating layer, on the one hand, increases the strength and torsional strength of the edge portion of the positive electrode current collector, thereby effectively preventing the occurrence of folding at the edge of the first hollow foil surface; on the other hand, even if the edge of the first hollow foil surface folds, the insulating layer can effectively prevent the electrical connection between the positive electrode current collector and the negative electrode active layer, thereby significantly reducing the risk of short circuit in the battery cell and improving the safety of the battery. The design of the adhesive enhances the connection strength between the positive electrode sheet and the membrane shell, thereby effectively reducing the probability of the first hollow foil surface being squeezed against the inner wall of the membrane shell by battery vibration and folding. The insulating layer and the adhesive do not overlap, and the thickness loss caused by the overlap of the adhesive and the insulating layer is avoided, thereby improving the volume utilization of the battery and enhancing the overall performance and safety.

[0057] The contents of this application will be described in detail below with reference to the accompanying drawings so that those skilled in the art can understand the contents of this application more clearly and in detail.

[0058] The specific structure of the battery and various possible implementation methods are described in detail below.

[0059] Figure 1 This is one of the structural schematic diagrams of the winding core provided in an embodiment of the present application. Figure 2 for Figure 1 Schematic diagram of the structure of the positive electrode sheet of the winding core shown. Figure 3 This is the second structural schematic diagram of the winding core provided in an embodiment of the present application. Figure 4 for Figure 3 Schematic diagram of the structure of the positive electrode sheet of the winding core shown. Figure 5 This is the third structural schematic diagram of the winding core provided in an embodiment of the present application. Figure 6 This is the fourth structural schematic diagram of the winding core provided in an embodiment of the present application. Figure 7 Schematic diagram of the structure of the positive electrode sheet of the winding core provided in an embodiment of the present application. Figure 8 This is one of the structural schematic diagrams of the stacked positive electrode sheet, separator and negative electrode sheet of the winding core provided in an embodiment of the present application. Figure 9 This is the second structural schematic diagram of the stacked positive electrode sheet, separator and negative electrode sheet of the winding core provided in an embodiment of the present application. Figure 10 This is one of the structural diagrams of the electronic device provided in the embodiment of the present application. Figure 11 This is the second structural diagram of the electronic device provided in an embodiment of the present application.

[0060] like Figure 1 and Figure 10 As shown, the battery 100 provided in the embodiment of the present application is used in an electronic device 200 .

[0061] like Figure 11As shown, the battery 100 includes a film shell 101 and a winding core 102. The winding core 102 is located in the film shell 101. Specifically, the film shell 101 is an aluminum-plastic film, which is a multi-layer composite structure of PP layer, aluminum foil layer and nylon layer.

[0062] like Figure 1 、 8 As shown in FIG9 , the winding core 102 includes a positive electrode sheet 10, a separator 20, and a negative electrode sheet 30. The positive electrode sheet 10, the separator 20, and the negative electrode sheet 30 are stacked and wound in sequence to form a straight region 103 and arc regions 104 on both sides of the straight region 103.

[0063] It should be noted that since the positive electrode sheet 10, the separator 20 and the negative electrode sheet 30 are wound, the cross-section of the winding core 102 is in the shape of a runway. The straight area 103 is regarded as an area formed by two parallel straight lines on both sides, and the arc area 104 should be regarded as an area with arc curvature on both sides of the straight area 103.

[0064] It should be noted that in some embodiments, the direction in which the tab 60 extends is the length direction of the winding core 102. Figure 1 、 Figure 2 and Figure 5 The length direction of the positive electrode sheet 10, the separator 20 and the negative electrode sheet 30 and the width direction of the core 102 can be considered to be the same direction, that is, the X direction; the width direction of the positive electrode sheet 10, the separator 20 and the negative electrode sheet 30 and the length direction of the core 102 can be considered to be the same direction, that is, the Y direction; the thickness (height) direction of the core 102 is the Z direction; among them, the three directions X, Y and Z are perpendicular to each other.

[0065] like Figure 7 As shown, the positive electrode sheet 10 includes a positive electrode current collector 11 and positive electrode active layers 12 located on both sides of the positive electrode current collector 11. At least a portion of the surface of the positive electrode active layer 12 is provided with a recess 121.

[0066] By providing a recess 121 on the surface of the positive electrode active layer 12, the CB value of the corresponding position can be increased (the CB value is the ratio of the capacity of the cathode active material per unit area to the capacity of the anode active material per unit area), thereby preventing lithium plating to improve safety. The recess 121 can also store electrolyte, improve the wetting performance of the electrolyte on the electrode, and improve the overall dynamic performance of the battery cell. The benefits will be higher, meet the fast charging requirements, improve edge lithium plating, and thus increase the cycle life of the battery 100.

[0067] As an optional embodiment, a plurality of recesses 121 are arranged at intervals in the straight area 103 and the arc area 104 .

[0068] As an optional implementation, the depth of the concave portion 121 is H. Wherein, H satisfies: 10 μm≤H≤160 μm.

[0069] Optimal: 70um≤H≤150um.

[0070] Along the winding direction, the length of the positive electrode current collector 11 is greater than the length of the positive electrode active layer 12 located on both sides thereof, and a first hollow foil surface 13 and a second hollow foil surface are formed at the tail of the positive electrode current collector 11 .

[0071] like Figure 1 and Figure 3 As shown, the first empty foil surface 13 is located on the side of the positive electrode current collector 11 away from the winding center. The second empty foil surface is located on the side of the positive electrode current collector 11 closer to the winding center. At least a portion of the first empty foil surface 13 is located in the straight area between the first to last fold of the positive electrode current collector 11 and the straight area between the second to last fold of the positive electrode current collector 11.

[0072] The straight region 103 of the penultimate fold of the positive electrode current collector 11 and the straight region 103 of the penultimate fold of the positive electrode current collector 11 are located on two opposite sides of the winding core 102 .

[0073] like Figure 2 and Figure 4 As shown, the winding core 102 also includes an adhesive 40 and an insulating layer 50. The adhesive 40 adheres to the trailing end of the positive electrode sheet 10 in the winding direction and the inner wall of the membrane shell 101. The adhesive 40 is provided on the bare foil surface. At least a portion of the insulating layer 50 is located in the straight region 103 of the penultimate fold of the first bare foil surface 13.

[0074] Specifically, refer to Figure 5 The side of the adhesive 40 away from the inner wall of the membrane shell 101 is bonded to the first empty foil surface 13 located at the straight area of ​​the first to last fold of the positive electrode current collector 11 and the straight area of ​​the third to last fold of the positive electrode current collector 11.

[0075] Along the width direction of the positive electrode current collector 11 , the insulating layer 50 extends to the edge of the positive electrode current collector 11 .

[0076] In the orthographic projection of the winding core 102 in the thickness direction, the insulating layer 50 and the adhesive material 40 do not overlap with each other.

[0077] By forming a first hollow foil surface 13 and a second hollow foil surface at the tail of the positive current collector 11, and providing an insulating layer 50 in the straight area 103 of the first hollow foil surface 13, the insulating layer 50 extends to the edge of the positive current collector 11. The setting of the insulating layer 50 is used to protect the edge of the positive current collector 11. On the one hand, it increases the strength and torsional strength of the edge part of the positive current collector 11, thereby effectively avoiding the occurrence of folding. On the other hand, even if folding occurs, the insulating layer 50 can effectively prevent the electrical connection between the positive current collector 11 and the negative electrode active layer, thereby significantly reducing the risk of short circuit of the core 102 and improving the safety of the battery 100. The adhesive 40 bonds the tail end of the positive electrode sheet 10 to the inner wall of the membrane shell 101, which increases the overall structural stability of the core 102 and prevents the displacement of internal components due to vibration or impact during use.

[0078] The insulating layer 50 and the adhesive 40 do not overlap each other, which also avoids thickness loss caused by the overlap of the adhesive 40 and the insulating layer 50, prevents the energy density from decreasing, improves the volume utilization of the battery 100, and enhances the overall performance.

[0079] As an optional embodiment, the adhesive member 40 is provided on the flat region 103 of the first hollow foil surface 13 , and a gap exists between the insulating layer 50 and the adhesive member 40 in the width direction of the positive electrode current collector 11 .

[0080] As an optional embodiment, along the width direction of the positive electrode current collector 11 , the gap between the insulating layer 50 and the adhesive 40 is W0 , where W0 satisfies: W0 ≥ 3 mm.

[0081] As an optional embodiment, along the width direction of the positive electrode current collector 11 , the insulating layer 50 covers at least a portion of the side surface of the positive electrode current collector 11 .

[0082] It should be noted that the positive electrode current collector 11 is a sheet of metal foil with a thickness of usually 3um-10um. Its two opposing coated surfaces with larger areas are used to coat the positive electrode active layer, while it has multiple side surfaces with smaller areas in the thickness direction, and the coated surface is approximately perpendicular to the multiple side surfaces. When die-cutting the positive electrode current collector 11, the cutter may form burrs on the side surface after die-cutting.

[0083] The insulating layer 50 covers the side surfaces of the positive electrode current collector 11, effectively isolating and covering burrs on the side surfaces of the positive electrode current collector 11 caused by cutting. This reduces the probability of the positive electrode current collector 11 puncturing the separator and contacting the negative electrode sheet 30 when folded, thereby reducing the risk of short circuits and improving battery safety. Furthermore, the insulating layer 50 acts as a physical barrier, protecting the side surfaces of the positive electrode current collector 11 from chemical, electrochemical, or mechanical damage, thereby extending the service life of the battery 100.

[0084] At the same time, the edge of the positive electrode current collector 11 may be an area of ​​concentrated electric field, which can easily cause local overheating or discharge. The insulating layer 50 material generally has certain thermal resistance properties. The insulating layer 50 can reduce this edge effect, reduce the local electric field strength, help manage the heat distribution within the battery 100, prevent local overheating, and improve the thermal stability of the battery 100.

[0085] As an optional embodiment, the insulating layer 50 has a size W1 along the width direction of the positive electrode current collector 11 , wherein W1 satisfies: 0.2 mm ≤ W1 ≤ 30 mm.

[0086] In this way, it can be ensured that even after the first hollow foil surface 13 is folded over at the top and / or bottom edge along the length direction of the battery cell, there is still a sufficient insulating layer between it and the negative electrode active layer; it also avoids the insulating layer 50 being too wide, thereby improving the overall quality of the winding core and further increasing the potential energy of the winding core when it falls, causing the first hollow foil surface 13 to tear and contact the negative electrode active layer, thereby ensuring safety.

[0087] Optionally, in some embodiments, W1 can be any value such as 0.5 mm, 1 mm, 2 mm, 3 mm, 5 mm, 7 mm, 10 mm, 15 mm, 20 mm, 25 mm, etc.

[0088] As an optional embodiment, the winding core 102 further includes a tab 60 . In the thickness direction of the winding core 102 , there is a gap between the orthographic projection of the insulating layer 50 and the orthographic projection of the tab 60 .

[0089] By providing a gap between the insulating layer 50 and the orthographic projection of the tab 60, the tab 60 can be avoided, preventing unnecessary material from accumulating at the tab 60 and reducing stacking in the thickness direction, thereby reducing the overall thickness of the battery 100. This helps optimize the space utilization within the battery 100, thereby improving the energy density and power density of the battery 100 and facilitating the manufacture of thinner and lighter batteries. Furthermore, avoiding overlap between the insulating layer 50 and the tab 60 can reduce internal stress concentration, lowering the risk of failure under thermal cycling or mechanical vibration, thereby improving the structural integrity and reliability of the battery 100.

[0090] Reducing the stacking in the thickness direction can also achieve faster heat dissipation through a thinner battery structure, which can improve the thermal management performance of the battery 100, reduce the risk of overheating, and increase the safety and life of the battery 100.

[0091] As an optional embodiment, the gap between the orthographic projection of the insulating layer 50 and the orthographic projection of the tab 60 along the width direction of the winding core 102 is G. Here, G satisfies: 0.1 mm ≤ G ≤ 5 mm.

[0092] By setting an appropriate gap G, it is possible to ensure that there is no overlap between the insulating layer 50 and the tab 60 in the thickness direction, while also improving the protective effect of the insulating layer 50 and meeting the current carrying capacity of the tab 60. This balance is achieved between reducing the overall thickness and weight of the battery 100, enhancing the safety of the battery 100, and ensuring the performance and efficiency of the battery 100. Smaller gaps, such as 0.1mm, 0.5mm, and 1mm, can ensure the safety of the battery 100 and improve the performance and efficiency of the battery 100; larger gaps, such as 4mm and 5mm, can ensure no overlap in the thickness direction and reduce the overall thickness of the battery 100. Through reasonable spatial configuration, structural optimization and performance improvement are achieved, ensuring the comprehensive performance of the battery 100 in terms of safety, efficiency, and reliability.

[0093] As an optional embodiment, along the length direction of the positive electrode sheet 10, the gap between the recess 121 and the head of the positive electrode active layer 12 is K1, the gap between the recess 121 and the head of the tab 60 is K2, the gap between the recess 121 and the tail of the tab 60 is K3, and the gap between the recess 121 and the tail of the positive electrode active layer 12 is K4. Along the width direction of the positive electrode sheet 10, the gap between the recess 121 and the edge of the positive electrode sheet 10 with the tab 60 is W4, and the gap between the recess 121 and the edge of the positive electrode sheet 10 facing away from the tab 60 is W5.

[0094] Among them, K1, K2, K3, K4, W4, and W5 meet the following requirements:

[0095] 0≤K1≤80mm; and / or

[0096] 0≤K2≤60mm; and / or

[0097] 0≤K3≤60mm; and / or

[0098] 0≤K4≤60mm; and / or

[0099] 0≤W4≤18mm; and / or

[0100] 0≤W5≤18mm.

[0101] Preferably, 40 mm ≤ K1 ≤ 70 mm; and / or

[0102] 5mm≤K2≤35mm; and / or

[0103] 5mm≤K3≤35mm; and / or

[0104] 5mm≤K4≤35mm; and / or

[0105] 2mm≤W4≤12mm; and / or

[0106] 2mm≤W5≤12mm.

[0107] As an optional embodiment, the insulating layer 50 includes a first sublayer 51 and a second sublayer 52. Along the width direction of the positive electrode current collector 11, the first sublayer 51 extends to one edge of the positive electrode current collector 11, and the second sublayer 52 extends to the other edge of the positive electrode current collector 11.

[0108] By dividing the insulating layer 50 into two sublayers, each covering the edges of the positive electrode current collector 11, comprehensive electrical isolation is effectively provided, preventing accidental contact between the positive electrode current collector 11 and the negative electrode sheet 30, and reducing the risk of short circuits. Furthermore, the two sublayers provide additional mechanical protection for both edges of the positive electrode current collector 11, increasing its strength and torsional resistance and reducing edge folding caused by external forces or vibration.

[0109] Layered design allows for more precise control over the use of insulation materials, ensuring adequate protection where needed without adding unnecessary material thickness or weight. Layered design provides greater flexibility in selecting different materials or thicknesses to meet specific electrical, mechanical, or thermal management needs.

[0110] like Figure 5 and Figure 6 As shown, as an optional embodiment, the core 102 further includes adhesive tape 70. Along the length of the core 102, the tab 60 is located at one end of the core 102 and extends away from the core 102. The insulating layer 50 extends to the edge of the positive electrode current collector 11 near the tab 60. The adhesive tape 70 is located at the end of the core 102 away from the tab 60. Along the thickness direction of the core 102, the adhesive tape 70 covers the two opposite sides of the core 102.

[0111] The adhesive tape 70 wraps around the edge of the positive electrode current collector 11 at the end of the winding core 102 away from the tab 60, providing the same effect as the insulating layer 50, thereby covering both sides of the positive electrode current collector 11. On the one hand, it increases the strength and torsional strength of the edge portion of the positive electrode current collector 11, thereby effectively preventing folding. On the other hand, even if folding occurs, the adhesive tape 70 can effectively prevent electrical connection between the positive electrode current collector 11 and the negative electrode active layer, thereby significantly reducing the risk of short circuiting of the winding core 102 and improving the safety of the battery 100.

[0112] The adhesive tape 70 is located at the end away from the tab 60 and covers the two opposite sides of the core 102. That is, the bottom of the core 102 away from the tab 60 can be encapsulated by a piece of adhesive tape 70 from one side of the core 102, wrapping the bottom of the core 102 and sticking it to the other opposite side. This design can increase the overall structural stability of the core 102 and prevent the components from shifting or loosening due to vibration or mechanical stress during operation and use. The adhesive tape 70 covers both sides of the core 102, especially at the end away from the tab 60, which can provide additional mechanical protection for the core 102 and reduce wear and damage caused by external force or friction.

[0113] The use of adhesive tape 70 also simplifies the assembly process of battery 100. By securing the winding core structure, it ensures that components remain in their designed positions during assembly and use, improving assembly efficiency and consistency. Furthermore, the area covered by adhesive tape 70 helps evenly distribute heat, preventing localized overheating and improving the thermal management and safety of battery 100.

[0114] As an optional embodiment, along the width direction of the roll core 102, the ratio of the length of the adhesive tape 70 to the length of the straight area 103 is greater than 70%.

[0115] By covering more than 70% of the flat area 103 with adhesive tape 70, the adhesive tape 70 provides additional mechanical support and stability to the winding core 102, reducing component displacement or deformation caused by vibration or mechanical stress during operation and use. The adhesive tape 70 provides additional mechanical and environmental protection to the flat area 103 of the winding core 102, reducing wear and damage caused by external forces, moisture, or chemicals, thereby extending the service life of the battery 100.

[0116] Covering most of the flat area 103 with adhesive tape 70 helps evenly distribute heat and prevent localized overheating, thereby improving the thermal management and overall safety of the battery 100. Furthermore, the extensive adhesive tape 70 coverage effectively increases electrical insulation within the battery 100, preventing accidental contact between different battery components, reducing the risk of short circuits, and enhancing battery safety. This extensive adhesive tape 70 coverage simplifies the manufacturing and assembly process. By securing the structure of the winding core 102, it ensures that components remain in their designed positions during assembly and use, improving assembly efficiency and consistency.

[0117] Preferably, along the width direction of the roll core 102 , the adhesive tape 70 extends to at least one side of the arc area 104 .

[0118] By extending the adhesive tape 70 to the arc region 104, additional protection is provided for the arc region 104 of the core 102. When the core 102 is inserted into the case, the arc region 104 is compressed at the corners to form a multi-layered, corrugated cushioning structure. This cushioning structure, which absorbs electrolyte, absorbs and disperses external mechanical shock or vibration, reducing direct impacts on the core 102, thereby improving the impact resistance and overall mechanical stability of the battery 100.

[0119] At the same time, the tape 70 can store some electrolyte inside the arc area, which not only helps maintain the electrochemical performance of the battery 100, but the stored electrolyte can also absorb some heat when the temperature rises, thereby helping the battery 100 to dissipate heat more effectively, reducing the risk of overheating, and can, to a certain extent, improve the thermal management capabilities of the battery 100, enhancing the thermal stability and safety of the battery 100. The additional coverage of the tape 70 can protect the arc area 104 of the winding core 102 from environmental factors, thereby extending the service life of the battery 100. The tape 70 covering the arc area 104 can also increase the electrical insulation effect inside the battery, preventing accidental electrical contact in the edge area, reducing the risk of short circuits, and improving the safety of the battery 100.

[0120] As an optional implementation, the thickness of the adhesive tape 70 ranges from 8um to 20um.

[0121] The thickness of the adhesive tape 70 is preferably 16 μm.

[0122] As an optional embodiment, the material of the adhesive tape 70 includes PET, PI, etc., and the type is not limited.

[0123] As an optional embodiment, in the orthographic projection in the thickness direction of the winding core 102 , the tab 60 and the adhesive 40 do not overlap each other. That is, there is a gap between the orthographic projection of the adhesive 40 and the orthographic projection of the tab 60 .

[0124] By ensuring that the tab 60 and the adhesive 40 do not overlap, the tab 60 can be avoided, unnecessary material stacking can be avoided, and stacking in the thickness direction can be reduced, thereby reducing the overall thickness of the battery 100. This helps optimize the space utilization within the battery 100, thereby improving the energy density and power density of the battery 100 and facilitating the manufacture of thinner and lighter batteries. Furthermore, by avoiding overlap between the tab 60 and the adhesive 40, internal stress concentration can be reduced, lowering the risk of failure under thermal cycling or mechanical vibration, thereby improving the structural integrity and reliability of the battery 100.

[0125] Reducing the stacking in the thickness direction can also achieve faster heat dissipation through a thinner battery structure, which can improve the thermal management performance of the battery 100, reduce the risk of overheating, and increase the safety and life of the battery 100.

[0126] As an optional embodiment, along the winding direction, at least part of the insulating layer 50 is located in the straight area 103 of the first hollow foil surface 13 at the penultimate fold and / or the straight area 103 of the third penultimate fold.

[0127] The straight region 103 of the penultimate fold of the positive electrode current collector 11 and the straight region 103 of the penultimate fold of the positive electrode current collector 11 are located on the same side of the winding core 102 .

[0128] By providing an insulating layer 50 on the straight region 103 of the first bare foil surface 13 at the penultimate fold and / or the straight region 103 of the third-to-last fold, this layer, in conjunction with the insulating layer 50 on the straight region 103 of the second-to-last fold of the first bare foil surface 13, increases the strength and torsional resistance of the edge portion of the positive electrode current collector 11, thereby effectively preventing folding. Furthermore, even if folding occurs, the insulating layer 50 on each straight region 103 effectively prevents electrical connection between the positive electrode current collector 11 and the negative electrode active layer, significantly reducing the risk of short circuiting of the core 102 and improving the safety of the battery 100.

[0129] like Figure 1 and Figure 2 As shown, as an optional embodiment, the insulating layer 50 extends to the arc region 104 on one side along the winding direction and covers at least two straight regions 103 connected to the arc region 104 .

[0130] By covering the arc region 104 and the connected straight region 103, the insulating layer 50 completely surrounds the edge of the positive electrode current collector 11, which can increase the strength and torsional strength of the positive electrode current collector 11 at the edge of the arc region 104 and the connected straight region 103, thereby more effectively avoiding the occurrence of folding, reducing the risk of short circuit, and improving the safety of the battery 100. At the same time, the insulating layer 50 covers the arc region 104 and the connected straight region 103, which can provide additional mechanical protection for these areas, reduce damage or wear caused by external force or vibration, and thus improve the durability of the battery 100. The insulating layer 50 covering the arc region 104 and the connected straight region 103 can simplify the manufacturing and assembly process through the continuous insulating layer 50, ensure that the components remain in the designed position during assembly and use, and improve assembly efficiency and consistency.

[0131] As an optional embodiment, the distance between the head of the insulating layer 50, as projected in the thickness direction of the winding core 102, and the adjacent straight region 103 is D1. The distance between the tail of the insulating layer 50, as projected in the thickness direction of the winding core 102, and the adjacent straight region 103 is D2.

[0132] Wherein, D1 and D2 satisfy: D1 ≥ 0.2 mm; and / or D2 ≥ 0.2 mm.

[0133] By ensuring an appropriate distance between the head and tail of the insulating layer 50 and the adjacent flat area 103, the insulating layer 50 can more effectively surround the edge of the positive current collector 11, providing optimal protection and preventing the edge of the positive current collector 11 from being exposed, thereby reducing the risk of short circuits and other electrical failures. By having a continuous insulating layer 50 that extends to and covers the arc R corner area of ​​the winding core 102, additional protection can be provided for these areas that are easily impacted when falling. The arc R corner is where mechanical and electrical stresses tend to concentrate. By covering these areas, the safety performance of the battery can be significantly improved. By completely surrounding and covering these critical areas, the insulating layer 50 provides more comprehensive protection, reducing the risk of damage to the battery 100 due to mechanical shock, vibration or thermal stress during operation and use, and improving overall safety.

[0134] like Figure 3 and Figure 4 As shown, as an optional embodiment, the insulating layer 50 includes two parts, and the two parts of the insulating layer 50 are respectively located in two straight areas 103 connected to the arc area 104, and there is a gap between the insulating layer 50 and the adjacent arc area 104.

[0135] By not providing the insulating layer 50 in the arc region 104 , stacking of the insulating layer 50 in the width direction caused by providing the insulating layer 50 in the arc region 104 can be avoided, thereby improving the energy density. In addition, the insulating layer 50 protects the outermost straight region 103 of the winding core 102 which is most easily folded.

[0136] As an optional implementation, the distance between the head of the insulating layer 50 and the adjacent arc region 104 is D3, and the distance between the tail of the insulating layer 50 and the adjacent arc region 104 is D4.

[0137] Wherein, D3 and D4 satisfy: D3 ≥ 0.2 mm; and / or D4 ≥ 0.2 mm.

[0138] The lengths of the two portions of the insulating layer 50 may be different.

[0139] As an optional implementation, the adhesive 40 is hot melt adhesive.

[0140] As an optional embodiment, the insulating layer 50 includes at least one of ceramic or encapsulating materials such as PET, PI, etc.

[0141] The ceramic material can increase sufficient strength of the edge of the positive electrode current collector 11 and insulate the edge of the positive electrode current collector 11 to avoid short circuit with the negative electrode after folding.

[0142] As an optional embodiment, when the insulating layer 50 is a ceramic layer, the thickness of the coated ceramic is in the range of 1 um to 6 um.

[0143] The thickness of the coated ceramic is preferably 1.5um-3.5um. In this way, the ceramic particles are coated relatively thinly and relatively unevenly, which will increase the surface roughness, but at the same time can ensure that the colloid is evenly distributed to ensure the overall insulation effect of the insulation layer 50.

[0144] In this way, during the hot pressing process, some ceramic particles will be embedded in the membrane shell 101, thereby improving the connection strength between the ceramic and the membrane shell 101, thereby preventing the positive electrode sheet 10 from being folded.

[0145] More preferably, the ceramic layer comprises at least one of boehmite, alumina, zirconium dioxide, titanium dioxide, magnesium oxide, magnesium hydroxide, silicon dioxide, montmorillonite,

[0146] As an optional embodiment, the ceramic layer is mainly composed of aluminum oxide and has an off-white appearance.

[0147] As an optional embodiment, the film shell 101 is an aluminum-plastic film, and the ceramic particles will be embedded in the PP layer of the aluminum-plastic film during the hot pressing process.

[0148] As an optional implementation, the thickness of the aluminum-plastic film ranges from 70um to 200um.

[0149] As an optional embodiment, when the insulating layer 50 is made of a plastic encapsulating material such as PET or PI, the thickness of the plastic encapsulating material ranges from 8 um to 20 um.

[0150] The thickness of the encapsulation material is preferably 16 μm.

[0151] As an optional embodiment, the charge cut-off voltage of the battery 100 is ≥4.48V, and the separator 20 is a melamine separator.

[0152] The modified melamine salt decomposes when exposed to rapid heat generation, absorbing heat and lowering the temperature. This heat absorption property helps manage temperature rises within the battery 100, preventing overheating and improving the thermal stability of the battery 100. The structural properties of the melamine separator help improve the mechanical safety of the battery 100 by preventing separator rupture or electrode contact due to thermal expansion.

[0153] At the same time, the gases produced by the decomposition of melamine salts can dilute reactive oxygen species, thereby reducing the likelihood of thermal runaway in electrochemical devices. This mechanism is particularly important under high voltage and high temperature conditions because it can prevent catastrophic failure caused by chain reactions within the battery 100. In high voltage systems, heating of the battery 100 may cause expansion and folding problems. The melamine separator can effectively reduce these problems through its thermal management properties, ensuring the structural integrity of the battery under high pressure and high temperature conditions. Moreover, under high temperature conditions, the carbonized product of the modified melamine salt can maintain the coating structure of the separator 20, helping to prevent further contact between the positive electrode sheet 10 and the negative electrode sheet 30, reducing the possibility of short circuits, thereby improving the high temperature storage performance and mechanical safety performance of the battery 100.

[0154] As an optional embodiment, along the winding direction, a composite region 105 is provided between the tail of the negative electrode sheet 30 and the separator 20 .

[0155] The composite region 105 tightly bonds the negative electrode sheet 30 to the separator 20, forming a stable connection area. This increases mechanical stability and reduces displacement or delamination caused by vibration or mechanical stress during operation and use. The composite region 105 helps prevent direct contact between the negative electrode sheet 30 and the positive electrode sheet 10, thereby reducing the risk of short circuits. It effectively isolates the negative electrode sheet 30 and prevents accidental contact that may occur during electrochemical reactions.

[0156] The presence of the composite region 105 also helps reduce warping or deformation of the negative electrode sheet 30 during the winding process, ensuring the structural integrity of the battery 100 during assembly and use. This improves the consistency and reliability of the battery 100 manufacturing process, ensuring that the structure and performance of each battery 100 meet design standards.

[0157] As an optional embodiment, along the width direction of the positive electrode sheet 10 , the size of the recombination area 105 is L, where L satisfies: L≥0.05 mm.

[0158] By ensuring that the size of the composite region 105 is no less than 0.05 mm, sufficient material overlap and bonding area can be provided, thereby enhancing the mechanical stability between the negative electrode sheet 30 and the separator 20 and reducing delamination or displacement caused by mechanical stress during operation and use. Appropriate dimensions of the composite region 105 help maintain electrical insulation between the negative electrode sheet 30 and the positive electrode sheet 10, reducing the risk of short circuits and improving battery safety. Ensuring a sufficient size for the composite region 105 can reduce material stress concentration and the risk of failure under thermal cycling or mechanical vibration, thereby improving the structural integrity of the battery 100.

[0159] Setting the minimum size of the composite region 105 to 0.05 mm can improve the tolerance range in the manufacturing process, reduce the risk of inconsistent performance or failure due to manufacturing deviations, and thus improve the consistency and reliability of the product.

[0160] As an optional embodiment, the two composite areas 105 include two composite areas 105 , which are respectively located in two straight areas 103 connected to the arc area 104 , and there is a gap between the composite area 105 and the adjacent arc area 104 .

[0161] By providing composite regions 105 within flat regions 103, the mechanical stability of these regions can be enhanced, reducing delamination or displacement caused by mechanical stress during operation and use. This design can simplify the manufacturing and assembly process, providing a clear structural layout, reducing complexity and potential errors during assembly, and improving production efficiency and consistency.

[0162] The gap between the recombination zone 105 and the arc zone 104 allows for a certain buffer space during thermal expansion or mechanical deformation, thereby optimizing stress distribution, reducing stress concentration, and improving the structural integrity of the battery 100. Providing the recombination zone 105 in the straight region 103 and maintaining a gap with the arc zone 104 helps maintain electrical insulation between the electrodes, reduces the risk of short circuits, and improves the safety of the battery 100.

[0163] As an optional implementation, the distance between the head of the composite region 105 and the adjacent arc region 104 is D5, and the distance between the tail of the composite region 105 and the adjacent arc region 104 is D6.

[0164] Wherein, D5 and D6 satisfy: D5 ≥ 0.2 mm; and / or D6 ≥ 0.2 mm.

[0165] Setting the minimum distances D5 and D6 to 0.2 mm or greater can increase the tolerance range during the manufacturing process, reduce the risk of inconsistent performance or failure due to manufacturing deviations, and thus improve production efficiency and consistency.

[0166] Maintaining an appropriate distance between the recombination zone 105 and the arc zone 104 reduces mechanical stress concentration. This design allows for a buffer space during thermal expansion or mechanical deformation, thereby improving the structural integrity of the battery 100. Proper spacing helps maintain electrical insulation between the electrodes, reduces the risk of short circuits, ensures effective isolation between the electrodes and the separator, and enhances battery safety.

[0167] As an optional embodiment, the composite area 105 includes at least one of overall composite, vertical line composite, pattern composite, and dot composite.

[0168] The composite area 105 may be in various forms, including overall composite, vertical line composite, pattern composite and dot composite, each of which has its own unique advantages.

[0169] The monolithic composite provides a uniform bonding surface, ensuring good contact between the electrode and separator, and improving the battery's overall mechanical stability. It also enhances structural strength and reduces the risk of delamination and displacement. Furthermore, the monolithic composite's manufacturing process is relatively simple, making it suitable for large-scale production.

[0170] The vertical composite provides a certain degree of flexibility, allowing the material to move during thermal expansion, reducing stress concentration. The vertical composite can form longitudinal channels, which facilitate the flow of electrolyte and ion transport, improving battery performance.

[0171] The pattern composite provides an aesthetically pleasing appearance, and the pattern design optimizes the contact area and channel structure, balancing mechanical strength and flexibility. The complex pattern helps dissipate heat and improve thermal management performance.

[0172] Dot-type composites provide additional mechanical reinforcement in critical areas, reducing local stress concentrations. Dot-type composites also reduce material usage and cost while maintaining necessary mechanical properties. The dot-type structure also facilitates the flow of air or electrolyte, improving heat dissipation and ion transport.

[0173] As an optional implementation, the composite region 105 includes vertical line composites, the interval width between the vertical lines is L1, and the vertical line width is W3.

[0174] Wherein, L1 and W3 satisfy: 0.5mm≤L1≤3mm; and / or 30um≤W3≤300um.

[0175] The vertical lines are spaced apart to prevent the membrane 20 from everting outward, while allowing for sufficient space for stretching and wrinkling. By controlling the width of the spacing between the vertical lines, sufficient mechanical strength can be achieved while allowing for flexibility, minimizing material deformation and damage caused by thermal expansion or mechanical stress. Appropriate vertical line width ensures sufficient contact area to maintain structural strength while avoiding material waste caused by excessive coverage.

[0176] By adjusting the dimensions of L1 and W3, the composite region 105 can be flexibly designed to accommodate different application requirements and operating conditions while ensuring controllable and consistent manufacturing processes. The vertical composite structure helps evenly distribute mechanical stress and reduce stress concentration, thereby improving the structural integrity and service life of the battery 100.

[0177] As an optional embodiment, in the arc region 104 , the gap between the positive electrode sheet 10 and the negative electrode sheet 30 inside the winding core 102 is larger than the gap between the positive electrode sheet 10 and the negative electrode sheet 30 outside the winding core 102 .

[0178] As an optional embodiment, in the arc area 104, the gap between the positive electrode sheet 10 and the negative electrode sheet 30 on the inner side of the innermost three-layer winding core 102 and the gap between the positive electrode sheet 10 and the negative electrode sheet 30 on the outer side of the outermost three-layer winding core 102 differ by ≥0.15 mm.

[0179] As an optional embodiment, the radius of the arc area 104 is r, and the thickness of the winding core 102 is t, wherein r and t satisfy: 0.95≤r / t≤1.15.

[0180] Preferably, r / t=1.05.

[0181] When r / t is within an appropriate range, the electrolyte content in the arc region 104 can be increased, while ensuring the adhesion between the electrode and the diaphragm 20, greatly improving the arc lithium deposition and arc electrode fracture problems.

[0182] As an optional embodiment, the charging cut-off voltage of the battery cell is ≥4.48 V. The negative electrode sheet 30 includes a negative electrode active layer, which includes a silicon-based material. The silicon content of the silicon-based material in the negative electrode active layer is 2%-20%.

[0183] Silicon-based materials have an extremely high theoretical specific capacity (approximately 4200 mAh / g), far exceeding that of traditional graphite materials. The inclusion of silicon-based materials in the negative electrode active layer means that battery 100 can store more energy for the same volume or weight, thereby increasing its energy density. A moderate amount of silicon (2%-20%) can enhance the capacity and performance of battery 100 without significantly increasing volume change, helping to strike a balance between performance improvement and material stability. The high capacity of silicon-based materials helps improve the charge and discharge efficiency of battery 100, especially under high-rate charge and discharge conditions, providing better performance. Due to the high capacity of silicon-based materials, battery 100 can absorb more charge in a shorter period of time, supporting fast charging capabilities and meeting the fast charging requirements of modern electronic devices. Furthermore, silicon is an abundant and relatively inexpensive element. By partially replacing traditional graphite materials, it can reduce the cost of electrode materials and improve economic efficiency.

[0184] Although silicon undergoes significant volume changes during the charge and discharge process, by controlling the silicon content within the range of 2%-20%, and the silicon expanding during the cycle, the thickness of the positive electrode sheet can be made thicker after hot pressing, which can reduce the gap between the positive / negative electrode sheets and reduce the possibility of folding of the first empty foil area; in addition, it can also effectively reduce the damage to the electrode structure caused by this volume change, thereby extending the cycle life of the battery.

[0185] Among them, silicon-based materials can be realized by doping silicon, mixing single particles and secondary particles.

[0186] Incorporating silicon can significantly increase the specific capacity of the negative electrode and increase the overall energy density of the battery. Silicon's high capacity properties help improve the overall performance of the battery, especially in applications requiring high energy output.

[0187] By mixing single and secondary particles, the structural stability of the electrode can be optimized. The single particles provide high capacity, while the secondary particles help alleviate the stress caused by volume changes. This mixing strategy can reduce particle breakage and pulverization during charge and discharge, thereby extending the battery's cycle life.

[0188] The use of silicon-based materials can achieve high compaction, low area density, high energy density, and high voltage for the battery 100 .

[0189] High compaction can increase the content of active materials per unit volume, thereby improving the energy density of the battery. By increasing the compaction density, the capacity can be increased without increasing the volume of the battery. Low areal density design helps improve the rate performance of the battery and supports faster charging and discharging. Lower areal density can reduce the heat generated by the battery at high rates, improving safety and thermal management performance. High energy density means that the battery can store more energy in the same volume or weight, thereby extending the service life of the device. High voltage design can improve the power output capability of the battery and is suitable for application scenarios that require high power. High voltage can reduce current demand, thereby reducing circuit losses and improving overall system efficiency.

[0190] The mass content of element Si in the negative electrode active coating can be measured by conventional methods in the art, for example, as follows.

[0191] Test method: After discharging the battery to 0% SOC, disassemble the negative electrode sheet and soak it in dimethyl carbonate (DMC) solvent for 12 hours. Then rinse it with DMC solvent to remove the lithium salt attached to the negative electrode sheet. After drying, the negative electrode sheet is high-temperature treated at 400℃ in an inert atmosphere for 2 hours (for example, in a tube furnace under nitrogen or argon atmosphere). The negative electrode active coating can be peeled off from the negative electrode current collector and the negative electrode active coating is collected as a test sample. Using a thermogravimetric analyzer (such as a TGA 550 thermogravimetric analyzer), the test sample is 5mg-15mg. In an air or oxygen atmosphere, the temperature is increased from room temperature (25℃) to 900℃ at a rate of 10℃ / min and maintained at 900℃ for 40 minutes to allow non-silicon components in the negative electrode active coating to volatilize and silicon to be fully oxidized to silicon dioxide. The remaining substance is the ash of the negative electrode active coating. The mass content of element Si in the negative electrode active coating can be calculated based on the mass of the ash. The calculation formula is as follows: mass content of element Si in the negative electrode active coating = 7×mass of ash / (15×mass of test sample).

[0192] As an optional embodiment, the negative electrode sheet 30 is manufactured by batching, coating, rolling, and slitting.

[0193] The negative electrode sheet 30 is coated using a double-layer coating. Specifically, the coating ratio of slurry A (bottom layer): slurry B (surface layer) ranges from (3:7) to (7:3). The preferred slurry A: slurry B ratio is 5:5, thereby achieving a balance between fast charging and energy density.

[0194] As an optional embodiment, the number particle size range of the negative electrode is: the number particle size Dn10 ranges from 0.5um to 1.5um, the number particle size Dn50 ranges from 1.2um to 2.1um, the number particle size Dn90 ranges from 5.1um to 8.5um, and the number particle size Dn99 ranges from 9.5um to 16.2um.

[0195] Where Dn is the number distribution. For example, if Dn10 = 10 μm, this means that the sample being tested is a cluster of tiny particles, and the number of particles smaller than 10 μm accounts for 10% of the total number of particles. In other words, 10% of the particles in the cluster are smaller than 10 μm.

[0196] As an optional embodiment, the volume particle size range of the negative electrode is: the volume particle size Dv10 ranges from 0.5um to 6.1um, the volume particle size Dv50 ranges from 7.7um to 13.1um, the volume particle size Dv90 ranges from 14.1um to 25.1um, and the volume particle size Dv99 ranges from 23um to 400um.

[0197] Where Dv is the volume distribution. For example, if Dv10 = 10 μm, this means that the sample being tested is a cluster of tiny particles, and particles smaller than 10 μm account for 10% of the total volume. In other words, 10% of the total particle volume is composed of particles smaller than 10 μm.

[0198] This application provides the following battery preparation process:

[0199] Step 1: Prepare the positive electrode sheet: Prepare the positive electrode slurry and apply the positive electrode slurry on the current collector coated with ceramic, where the ceramic is located on the empty surface of the single-sided area. After baking, rolling and cutting, the positive electrode sheet is obtained;

[0200] The preparation and slitting methods of the ceramic-coated aluminum foil are as follows: ceramic slurry is prepared by mixing ceramic powder and a binder, and a ceramic layer is gravure-printed onto the current collector. The ceramic layer has a thickness of 5 μm and a width of 10 mm. The ceramic layer is then cut from the middle by slitting to form the top and bottom of two electrode pieces, each 5 mm wide. The head of the ceramic layer extends beyond the first fold arc by 2 mm, and the tail extends beyond the second fold arc by 2 mm.

[0201] The positive electrode slurry preparation method is as follows: after the conductive agent and PVDF glue are mixed evenly, lithium cobalt oxide is added and stirred evenly to obtain the positive electrode active material layer slurry.

[0202] The positive electrode active material layer is composed of 98.5 parts by mass of lithium cobalt oxide, 0.7 parts by mass of PVDF, and 0.8 parts by mass of a conductive agent, wherein the conductive agent is composed of conductive carbon black, single-walled carbon nanotubes, and multi-walled carbon nanotubes.

[0203] Step 2: Prepare the negative electrode sheet: prepare the negative electrode slurry, apply the negative electrode slurry on the carbon-coated copper foil, and bake and cut the negative electrode sheet;

[0204] Step 3: After the positive electrode is embossed, the separator and the negative electrode are folded and bonded by heat treatment at the last two folds. The positive electrode, negative electrode, and separator are then wound and coated to form a core.

[0205] The distance between the top and bottom ceramic layers and the hot melt adhesive is 3 mm.

[0206] The embossing dimensions are as follows: roller depth 80 μm; K1=55 mm; K2=10 mm; K3=10 mm; K4=10 mm; W4=5 mm; W5=5 mm.

[0207] The thermal composite dimensions of the diaphragm and the negative electrode are as follows: L = 0.3mm

[0208] The composite position is located at the last two folds of the negative pole and does not exceed the arc;

[0209] D5=0.3mm; D6=0.3mm; L1=2mm; W3=100um.

[0210] Step 4: The aluminum-plastic film is punched through the mold core to obtain the film shell;

[0211] Step 5: After the core is put into the film shell, it goes through packaging, baking, liquid injection, formation, sorting, secondary sealing, OCV and packaging to obtain the battery cell;

[0212] Step 6: The battery is obtained by pad printing, welding the protective plate, and sticking the bottom tape;

[0213] Step 7: Apply the adhesive layer to the aluminum-plastic film on the shallow pit surface of the battery and bond it to the cabin to obtain the final electronic equipment;

[0214] The thickness of the aluminum-plastic film shell is 70~200um;

[0215] The active material of the positive electrode active material layer includes one or more of lithium cobalt oxide, lithium iron phosphate, nickel cobalt manganese lithium, nickel cobalt aluminum lithium, lithium manganese oxide and lithium-rich manganese-based lithium.

[0216] The negative electrode active material layer includes, but is not limited to, one or more of natural graphite, artificial graphite, mesophase carbon microbeads, lithium titanate, silicon negative electrode, silicon-carbon negative electrode and alloy negative electrode.

[0217] Among them, the positive electrode adhesive is mainly polyvinylidene fluoride (PVDF) adhesive, and the negative electrode adhesive is mainly styrene-butadiene rubber.

[0218] The conductive agent includes at least one of conductive carbon black, Ketjen black, single-walled carbon nanotubes, and multi-walled carbon nanotubes.

[0219] On the other hand, the present application also provides an electronic device 200, comprising a cabin 201 and the aforementioned battery 100. The battery 100 is located in the cabin 201, and an adhesive layer 202 is provided between the battery 100 and the inner wall of the cabin 201. The adhesive layer 202 is located on the side of the winding core 102 facing away from the adhesive member 40.

[0220] Compared with setting the adhesive layer 202 on the side of the adhesive 40 facing the winding core 102, setting the adhesive layer 202 away from the adhesive 40 can extend the distance for vibration transmission to the penultimate folded flat area 103, reduce vibration, and thus improve the structural stability of the battery 100.

[0221] It should be noted that references in this specification to "one embodiment," "an embodiment," "an exemplary embodiment," "some embodiments," and the like indicate that the described embodiment may include a particular feature, structure, or characteristic, but not necessarily every embodiment includes that particular feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in conjunction with an embodiment, it is within the knowledge of those skilled in the art to implement such feature, structure, or characteristic in conjunction with other embodiments, whether explicitly described or not.

[0222] Generally speaking, terms should be understood, at least in part, based on the context in which they are used. For example, as used herein, the term "one or more" can be used to describe any feature, structure, or characteristic in the singular sense, or can be used to describe a combination of features, structures, or characteristics in the plural sense, depending at least in part on the context. Similarly, terms such as "a," "an," or "the" can also be understood to convey either singular or plural usage, depending at least in part on the context.

[0223] It should be readily understood that “on,” “above,” and “over” in this application should be interpreted in the broadest manner, such that “on” means not only “directly on something,” but also includes “on something” with intervening features or layers therebetween, and “above” or “over” includes not only the meaning of “above” or “over,” but also includes “above” or “over” with no intervening features or layers therebetween (i.e., directly on something).

[0224] Additionally, spatially relative terms, such as "below," "beneath," "beneath," "above," and the like, may be used herein for ease of description to describe the relationship of one element or feature to other elements or features as depicted in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may be otherwise oriented (rotated 90° or at other orientations), and the spatially relative descriptors used herein should be interpreted accordingly.

[0225] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A battery, characterized in that: It includes a membrane shell and a winding core located in the membrane shell; The winding core includes a positive electrode sheet, a separator, and a negative electrode sheet. The positive electrode sheet, the separator, and the negative electrode sheet are stacked and wound in sequence to form a straight area and arc areas on both sides of the straight area. The positive electrode sheet includes a positive electrode current collector and positive electrode active layers on both sides of the positive electrode current collector, and at least a portion of the surface of the positive electrode active layer is provided with a recessed portion. Along the winding direction, the length of the positive electrode current collector is greater than the length of the positive electrode active layer located on both sides thereof, and a first hollow foil surface and a second hollow foil surface are formed at the tail of the positive electrode current collector, the first hollow foil surface is located on the side of the positive electrode current collector away from the winding center, and at least a portion of the first hollow foil surface is located in the straight area of ​​the first to last fold of the positive electrode current collector and the straight area of ​​the second to last fold of the positive electrode current collector, wherein the straight area of ​​the first to last fold of the positive electrode current collector and the straight area of ​​the second to last fold of the positive electrode current collector are located on opposite sides of the winding core; The winding core also includes an adhesive and an insulating layer, wherein the adhesive is respectively bonded to the tail end of the positive electrode sheet in the winding direction and the inner wall surface of the membrane shell, and at least a portion of the insulating layer is located in the straight area of ​​the first hollow foil surface at the second to last fold. Along the width direction of the positive electrode current collector, the insulating layer extends to the edge of the positive electrode current collector, and in the orthographic projection in the thickness direction of the winding core, the insulating layer and the adhesive do not overlap with each other.

2. The battery according to claim 1, characterized in that The insulating layer covers at least a portion of a side surface of the positive electrode current collector along a width direction of the positive electrode current collector.

3. The battery according to claim 1, characterized in that The winding core further includes a tab, and in the thickness direction of the winding core, there is a gap between the orthographic projection of the insulating layer and the orthographic projection of the tab; A gap G is formed between the orthographic projection of the insulating layer and the orthographic projection of the tab along the width direction of the winding core, wherein G satisfies: 0.1 mm ≤ G ≤ 5 mm.

4. The battery according to claim 1, characterized in that The insulating layer includes a first sublayer and a second sublayer, and along the width direction of the positive electrode current collector, the first sublayer extends to one side edge of the positive electrode current collector, and the second sublayer extends to the other side edge of the positive electrode current collector; and / or The winding core further includes a tab and adhesive tape. Along the length direction of the winding core, the tab is located at one end of the winding core and extends away from the winding core. The insulating layer extends to the edge of the positive electrode current collector on one side close to the tab. The adhesive tape is located at the end of the winding core away from the tab. Along the thickness direction of the winding core, the adhesive tape covers two opposite sides of the winding core. Along the width direction of the winding core, the ratio of the length of the adhesive tape to the length of the straight area is greater than 70%; Preferably, along the width direction of the winding core, the adhesive tape extends to the arc area on at least one side.

5. The battery according to claim 1, characterized in that The winding core further includes a tab, wherein in an orthographic projection in the thickness direction of the winding core, the tab and the adhesive do not overlap with each other; Along the winding direction, at least part of the insulating layer is located in the straight area of ​​the first to last fold and / or the straight area of ​​the third to last fold of the first empty foil surface, wherein the straight area of ​​the first to last fold of the positive electrode collector and the straight area of ​​the third to last fold of the positive electrode collector are located on the same side of the winding core.

6. The battery according to claim 1, characterized in that The insulating layer extends to the arc region on one side along the winding direction and covers at least the two straight regions connected to the arc region; The distance between the head of the insulating layer in the thickness direction of the winding core and the adjacent straight area is D1, and the distance between the tail of the insulating layer in the thickness direction of the winding core and the adjacent straight area is D2, wherein D1 and D2 satisfy: D1 ≥ 0.2 mm; and / or D2 ≥ 0.2 mm.

7. The battery according to claim 1, characterized in that The adhesive is a hot melt adhesive; and / or The insulating layer comprises at least one of a ceramic layer, PET or PI; Preferably, when the insulating layer is a ceramic layer, the thickness of the coated ceramic is in the range of 1um-6um; More preferably, the ceramic layer includes at least one of boehmite, alumina, zirconium dioxide, titanium dioxide, magnesium oxide, magnesium hydroxide, silicon dioxide, and montmorillonite.

8. The battery according to claim 1, characterized in that Along the winding direction, a composite area is provided between the tail of the negative electrode sheet and the separator; Along the width direction of the positive electrode sheet, the size of the composite area is L, wherein L satisfies: L ≥ 0.05 mm; and / or The composite areas include two, the two composite areas are respectively located in the two straight areas connected to the arc areas, and there is a gap between the composite area and the adjacent arc areas; and / or The distance between the head of the composite area and the adjacent arc area is D5, and the distance between the tail of the composite area and the adjacent arc area is D6, wherein D5 and D6 satisfy: D5 ≥ 0.2 mm; and / or D6 ≥ 0.2 mm; and / or The composite area includes at least one of overall composite, vertical line composite, pattern composite, and dot composite; Preferably, the composite area includes vertical line composites, the interval width between the vertical lines is L1, and the vertical line width is W3, wherein L1 and W3 satisfy: 0.5mm≤L1≤3mm; and / or 30um≤W3≤300um.

9. The battery according to claim 1, characterized in that The charging cut-off voltage of the battery is ≥4.48V; The negative electrode sheet comprises a negative electrode active layer, the negative electrode active layer comprises a silicon-based material, and the silicon content of the silicon-based material in the negative electrode active layer is 2%-20%; and / or The diaphragm is a melamine diaphragm.

10. An electronic device, characterized in that: It comprises a cabin and a battery as described in any one of claims 1 to 9, wherein the battery is located in the cabin, an adhesive layer is provided between the battery and the inner wall surface of the cabin, and the adhesive layer is located on the side of the winding core away from the adhesive component.

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