Battery cell and battery
By setting the tail of the second electrode in the wound lithium battery cell to extend beyond the end of the first electrode, and by using precise coverage with finishing adhesive and protective adhesive, the problem of excessive thickness of the outer ring of the wound lithium battery is solved, thereby improving the energy density and electrochemical reaction efficiency of the battery.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- ZHEJIANG LIWINON ENERGY TECHNOLOGY CO LTD
- Filing Date
- 2025-06-24
- Publication Date
- 2026-07-14
Smart Images
Figure CN224501977U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of lithium battery technology, and in particular to a battery cell and battery. Background Technology
[0002] Lithium batteries, as energy storage devices containing lithium (including metallic lithium, lithium alloys, lithium ions, and lithium polymers) in an electrochemical system, are widely used in consumer electronics and other fields, becoming one of the core technologies driving the transformation of modern society towards low-carbon and intelligentization.
[0003] The mainstream types of lithium batteries on the market include stacked and wound types. Stacked batteries combine positive and negative electrodes with separators in sequence, which has advantages such as regular structure and low internal resistance. Wound batteries, on the other hand, are made by sequentially stacking and winding positive and negative electrodes with separators, which has certain advantages in terms of production efficiency and cost control, and therefore occupies a considerable share of the market.
[0004] However, the structural characteristics of wound batteries lead to performance bottlenecks in practical applications. In the cell thickness direction, due to the characteristics of the spiral winding process, the outermost long film end region of the electrode stacks with the innermost short film end region. Furthermore, the adhesive residue at the ends of the long and short film ends also stacks, causing the cell thickness at that corresponding location to reach its maximum value. This excessively thick local structure increases the proportion of ineffective space inside the battery, hindering the effective accumulation of active materials. On the other hand, the thickness non-uniformity leads to a longer migration path for lithium ions in the electrode material, exacerbating concentration polarization. The combination of these two factors significantly reduces the battery's energy density (ED), thus affecting key performance indicators such as battery life and charge / discharge speed, becoming a technical obstacle restricting the further expansion of wound lithium batteries in high-end applications. Utility Model Content
[0005] The main purpose of this invention is to propose a battery cell that aims to solve the technical problem of low battery energy density caused by excessive thickness of the battery cell at the end of the long film surface of the outer ring electrode in current wound battery cells.
[0006] To achieve the above objectives, this utility model proposes a battery cell, which includes a first electrode, a second electrode, and a separator, wherein the polarity of the second electrode is opposite to that of the first electrode.
[0007] The first electrode, the diaphragm, and the second electrode are stacked and wound together to form a core, and the first electrode has a long film surface and a short film surface on both sides along its thickness direction.
[0008] In the winding direction of the core, the tail of the second electrode extends beyond the end of the long film surface and the end of the short film surface of the first electrode, respectively. The distance between the end of the long film surface of the first electrode and the tail of the second electrode is L1, and the distance between the end of the short film surface of the first electrode and the tail of the second electrode is L2, satisfying: 0 < L1 < L2.
[0009] Optionally, the core has a first straight area, a first corner area, a second straight area, and a second corner area arranged sequentially along its winding direction, wherein the first corner area and the second corner area are arranged opposite to each other at the two ends of the first straight area and the second straight area in the width direction of the core;
[0010] The end of the long film surface of the first electrode, the end of the short film surface of the first electrode, and the tail of the second electrode are all located on one side of the first straight area and are adjacent to the first corner area.
[0011] Optionally, the battery cell further includes a first finishing adhesive, the head of which is bonded to the end of the short film surface of the first electrode, and the tail of which extends to the first corner area.
[0012] Optionally, in the winding direction of the core, the distance between the tail of the first finishing adhesive and the end of the first straight area near the first corner area is L3, and the maximum arc length of the first corner area is L4, satisfying: 0 < L3 < 1 / 2L4.
[0013] Optionally, the battery cell further includes a second finishing adhesive, the head of which is located in the first flat area, the head of which is bonded to the winding end of the long film surface of the first electrode, and the second finishing adhesive surrounds the first corner area, and the tail of which extends to the second flat area.
[0014] Optionally, the portion of the first finishing adhesive covering the end of the short film surface of the first electrode sheet does not overlap with the projection of the portion of the second finishing adhesive covering the winding end of the first electrode sheet in the thickness direction of the core.
[0015] Optionally, the battery cell further includes a protective adhesive, which is disposed on the innermost ring of the core;
[0016] The protective adhesive is located at the junction of the first straight area and the first corner area, and its projection shape in the height direction of the core is U-shaped. The protective adhesive is bonded to the second electrode sheet.
[0017] Optionally, along the winding direction of the core, at least one of the opposite ends of the protective adhesive does not coincide with the projection of the end of the long film surface of the first electrode in the thickness direction of the core.
[0018] Optionally, the thickness of the long film surface of the first electrode is less than or equal to the thickness of the short film surface of the first electrode.
[0019] This utility model also proposes a battery, which includes a casing and a battery cell as described above, wherein the battery cell is disposed in the casing.
[0020] In the wound structure of this utility model's battery cell, the tail of the second electrode extends beyond the ends of the long film surface and the short film surface of the first electrode. The distance between the end of the long film surface of the first electrode and the tail of the second electrode is L1, and the distance between the end of the short film surface of the first electrode and the tail of the second electrode is L2. By setting the distance relationship of 0 < L1 < L2, the ends of the long film surface and the short film surface of the first electrode are staggered and do not stack. Compared with the existing wound battery cell, the thickness of one short film surface can be reduced at the corresponding position in the end region of the long film surface of the first electrode, thereby reducing the maximum thickness of the corresponding battery cell and improving the battery energy density. Attached Figure Description
[0021] Figure 1 This is a schematic diagram of the battery cell structure in one embodiment of the present invention;
[0022] Figure 2 for Figure 1 Enlarged view of point A in the middle;
[0023] Figure 3 This is a schematic diagram of the battery cell structure in another embodiment of the present invention;
[0024] Figure 4 This is a schematic diagram showing the arrangement of the first finishing adhesive at the first corner area in one embodiment of the present invention;
[0025] Label Explanation:
[0026] label name label name 110 First Pole Film 120 cover plate 130 diaphragm 100 Roll core 111 Long film surface 112 Short film surface 101 First Straight Zone 102 First corner area 103 Second corner area 104 Second Straight Zone 140 First finishing glue 150 Second finishing glue 160 Protective adhesive
[0027] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation
[0028] The solutions in the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this utility model.
[0029] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.
[0030] It should also be noted that when a component is described as "fixed to" or "set on" another component, it can be directly on the other component or there may be an intervening component present. When a component is described as "connected to" another component, it can be directly connected to the other component or there may be an intervening component present.
[0031] Furthermore, the use of terms such as "first" and "second" in this utility model is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this utility model.
[0032] This utility model embodiment proposes a battery cell, referring to... Figure 1 and Figure 2 The battery cell includes a first electrode 110, a second electrode 120, and a separator 130, wherein the polarity of the second electrode 120 is opposite to that of the first electrode 110.
[0033] The first electrode 110, the diaphragm 130, and the second electrode 120 are stacked and wound together to form a core 100, and the first electrode 110 is provided with a long film surface 111 and a short film surface 112 on both sides along its thickness direction.
[0034] In the winding direction of the core 100, the tail of the second electrode 120 extends beyond the end of the long film surface 111 and the end of the short film surface 112 of the first electrode 110, respectively. The distance between the end of the long film surface 111 of the first electrode 110 and the tail of the second electrode 120 is L1, and the distance between the end of the short film surface 112 of the first electrode 110 and the tail of the second electrode 120 is L2, satisfying: 0 < L1 < L2.
[0035] The battery cell involved in this embodiment, as the core component of the battery, mainly includes a first electrode 110, a separator 130, and a second electrode 120. The first electrode 110, separator 130, and second electrode 120 are stacked and wound together to form a core 100. This stacked and wound core 100 structure provides the necessary space and conditions for the electrochemical reaction inside the battery cell. The second electrode 120 has the opposite polarity to the first electrode 110. Specifically, the first electrode 110 can be a positive electrode and the second electrode 120 can be a negative electrode; or, the first electrode 110 can be a negative electrode and the second electrode 120 can be a positive electrode. This embodiment does not limit this. The separator 130 is located between the positive and negative electrodes, playing a crucial role in isolating the positive and negative electrodes and preventing them from directly contacting and short-circuiting, while simultaneously allowing ions to pass through, ensuring the smooth progress of the electrochemical reaction.
[0036] The first electrode 110 has a long film surface 111 (with a longer area coated with active material) and a short film surface 112 (with a shorter area coated with active material) on its two sides along its thickness direction. After being stacked and wound with the separator 130 and the second electrode 120, the tail of the second electrode 120 extends beyond the ends of the long film surface 111 and the short film surface 112 of the first electrode 110, respectively, and satisfies: 0 < L1 < L2. Here, L1 is the distance between the end of the long film surface 111 of the first electrode 110 and the tail of the second electrode 120, and L2 is the distance between the end of the short film surface 112 of the second electrode 120 and the tail of the second electrode 120.
[0037] For example, the first electrode 110 is the positive electrode, with one side being a long film surface 111 and the other side a short film surface 112; the second electrode 120 is the negative electrode, with the opposite polarity to the positive electrode; the separator 130, made of polyethylene (PE) or polypropylene (PP), is located between the positive and negative electrodes. The electrodes are stacked in the order of "positive electrode - separator 130 - negative electrode" and then wound in a spiral to form a core 100. In the winding direction, the distance L1 from the end of the negative electrode beyond the end of the long film surface 111 of the positive electrode is 1 mm, and the distance L2 from the end of the short film surface 112 is 3 mm (satisfying 0 < L1 < L2). This is merely an example and not a limitation.
[0038] By setting the distance relationship between L1 and L2, the ends of the long film surface 111 and the short film surface 112 of the first electrode 110 are staggered in the winding core 100, avoiding direct stacking. Specifically, the distance beyond the end of the long film surface 111 of the second electrode 120 is shorter (L1) and longer (L2) than the end of the short film surface 112. Thus, during the winding process, the ends of the long film surface 111 and the short film surface 112 will not stack at the same position, reducing the local thickness. That is, compared with the existing wound cell, the thickness of one short film surface 112 can be reduced at the corresponding position of the end region of the long film surface 111 of the first electrode 110, thereby reducing the maximum thickness of the corresponding cell and improving the battery energy density.
[0039] In some embodiments, refer to Figure 3 The core 100 has a first straight area 101, a first corner area 102, a second straight area 104 and a second corner area 103 arranged sequentially along its winding direction. In the width direction of the core 100, the first corner area 102 and the second corner area 103 are arranged opposite to each other at the two ends of the first straight area 101 and the second straight area 104.
[0040] The end of the long film surface 111 of the first electrode 110, the end of the short film surface 112 of the first electrode 110, and the tail of the second electrode 120 are all located on one side of the first straight area 101 and are adjacent to the first corner area 102.
[0041] In the winding direction of the core 100, the core 100 is divided into a first straight area 101, a first corner area 102, a second straight area 104, and a second corner area 103. The first straight area 101 and the second straight area 104 are planar main areas in the core 100, which are the main bearing areas for the first electrode 110, the second electrode 120, and the diaphragm 130 to be stacked. The two are arranged opposite to each other in the thickness direction of the core 100. The first corner area 102 and the second corner area 103 are arranged opposite to each other in the curved areas at both ends of the first straight area 101 and the second straight area 104. They are arc-shaped structures formed by the electrode turning during the winding process. The two are symmetrical about the central axis of the first straight area 101 and the second straight area 104.
[0042] In the thickness direction of the core 100, the ends of the long film surface 111 and the short film surface 112 of the first electrode 110 and the tail of the second electrode 120 are all located in the first straight region 101. Furthermore, in the width direction of the core 100, the ends of the long film surface 111 and the short film surface 112 of the first electrode 110 and the tail of the second electrode 120 are disposed adjacent to the first corner region 102.
[0043] Taking the first electrode 110 as the positive electrode and the second electrode 120 as the negative electrode as an example (e.g.) Figure 1 As shown):
[0044] The middle part of the core 100 is the first straight area 101 and the second straight area 104. The first corner area 102 is located at the right end of the first straight area 101 and the second straight area 104, and the second corner area 103 is located at the left end of the first straight area 101 and the second straight area 104.
[0045] The ends of the long film surface 111 and the short film surface 112 of the positive electrode and the tail of the second electrode 120 are all located in the first straight region 101 and are adjacent to the first corner region 102 at the right end of the first straight region 101.
[0046] In some embodiments, refer to Figures 1 to 3 The battery cell also includes a first finishing adhesive 140. The head of the first finishing adhesive 140 is bonded to the end of the short film surface 112 of the first electrode 110, and the tail of the first finishing adhesive 140 extends to the first corner region 102. In this embodiment, the first finishing adhesive 140 serves as the finishing adhesive for the short film surface 112 of the first electrode 110. It can be made of high-temperature resistant and highly insulating adhesive paper, which has both bonding and insulating protection functions. The head of the first finishing adhesive 140 is fixedly bonded to the end of the short film surface 112 of the first electrode 110 (i.e., the termination position where the active material is coated on the short film surface 112), and the tail extends along the winding direction to the first corner region 102, covering the transition area from the end of the short film surface 112 to the first corner region 102. Specifically, the head of the first finishing adhesive 140 is aligned with the end of the short film surface 112, ensuring that it covers the uncoated area of the short film surface 112 (i.e., the exposed current collector portion). The tail extension path coincides with the spiral trajectory of the end of the short film surface 112 towards the first corner area 102, and is synchronously wound into the corner area along with the electrode sheet during the winding process. The first finishing adhesive 140 can fix the end of the short film surface 112, buffer the stress in the corner area, improve the forming accuracy and vibration resistance of the core 100, and also isolate the exposed current collector, strengthen interlayer insulation, and reduce the risk of short circuit.
[0047] The tail of the first finishing adhesive 140 extends only to the first corner area 102, but does not surround the first corner area 102 to extend to the other side of the first straight area 101 (i.e., the upper side of the first straight area 101). In the thickness direction of the core 100, the tail of the first finishing adhesive 140 is misaligned with the end of the long film surface 111 of the first electrode 110 and does not overlap. At the corresponding position of the end area of the long film surface 111 of the first electrode 110, the thickness of one adhesive paper can be reduced, so as to further reduce the maximum thickness of the corresponding cell and improve the energy density of the battery.
[0048] In some embodiments, refer to Figure 4In the winding direction of the core 100, the distance between the tail of the first finishing adhesive 140 and the end of the first straight area 101 near the first corner area is L3, and the maximum arc length of the first corner area 102 is L4, satisfying: 0 < L3 < 1 / 2L4.
[0049] In the winding direction of the core 100, the distance between the end point of the first finishing adhesive 140 and the end of the first straight area 101 near the first corner area 102 (i.e., the distance from the end point of the tail to the boundary line of the first straight area 101 / corner area) is L3, and the maximum arc length of the first corner area 102 (the curve length along the winding path) is L4, reflecting the spatial range of the corner area.
[0050] Wherein, 0 < L3 < 1 / 2 L4, this relationship defines the position of the tail of the first finishing adhesive 140 in the first corner area 102, ensuring that it is located in the latter half of the first corner area 102 along the winding direction, surrounding the first half of the first corner area 102 while not completely surrounding the entire first corner area 102. That is, the first finishing adhesive 140 covers most of the area of the first corner area 102 to ensure the fixing effect and avoid interlayer short circuits caused by insufficient protection.
[0051] In some embodiments, refer to Figures 1 to 3 The battery cell also includes a second finishing adhesive 150. The head of the second finishing adhesive 150 is located in the first flat region 101. The head of the second finishing adhesive 150 is bonded to the winding end of the long film surface 111 of the first electrode 110, and the second finishing adhesive 150 surrounds the first corner region 102. The tail of the second finishing adhesive 150 extends to the second flat region 104. In this embodiment, the second finishing adhesive 150 serves as the finishing adhesive for the long film surface 111 of the first electrode 110. Its material and type can be selected with reference to the first finishing adhesive 140, and will not be described in detail here. The second finishing adhesive 150 is precisely bonded at the winding end of the long film surface 111 of the first electrode 110 (i.e., the termination position where the active material is coated on the long film surface 111). Its main body extends along the winding direction and surrounds the first corner area 102, forming a ring-shaped enclosure around the outside of the corner area. After passing through the first corner area 102, the tail extends to the second straight area 104, forming a "bridging" structure across the corner area. The second finishing adhesive 150 can fix the end of the long film surface 111, buffer stress in the corner area, improve the forming accuracy and vibration resistance of the core 100, and also isolate the exposed current collector, strengthen interlayer insulation, and reduce the risk of short circuits. Furthermore, the second finishing adhesive 150 fixes the tail of the first electrode 110, reducing the risk of loosening on the outside of the core 100.
[0052] In some embodiments, refer to Figure 1 and Figure 2The portion of the first finishing adhesive 140 covering the end of the short film surface 112 of the first electrode 110 and the portion of the second finishing adhesive 150 covering the winding end of the first electrode 110 do not overlap in the thickness direction of the core 100.
[0053] From the perspective of the winding structure, the winding end of the first electrode 110, the end of the short film surface 112, and the tail of the second electrode 120 are all located in the first straight area 101 of the core 100 and adjacent to the first corner area 102. The head of the first finishing adhesive 140 is bonded to the end of the short film surface 112, and the tail extends to the first corner area 102; the head of the second finishing adhesive 150 is bonded to the winding end of the first electrode 110, the main body surrounds the first corner area 102 and extends to the second straight area 104. By precisely controlling the coverage position of the finishing adhesive, it is ensured that the projections of the two in the thickness direction of the core do not overlap.
[0054] In traditional battery cell structures, if the projections of the two end-covered adhesive regions overlap in the thickness direction, it will increase the local thickness of the core 100. However, in this embodiment, since the projections of the first and second end-covered adhesive regions do not overlap in the thickness direction, at the position corresponding to the winding end of the first electrode 110 and the end of the short film surface 112, no additional thickness will be generated due to the overlapping of adhesive layers, effectively reducing the overall thickness of the battery cell.
[0055] In some embodiments, refer to Figure 1 The battery cell also includes protective adhesive 160, which is located on the innermost ring of the core 100.
[0056] The protective adhesive 160 is located at the junction of the first straight area 101 and the first corner area 102, and its projection shape in the height direction of the core 100 is U-shaped. The protective adhesive 160 is bonded to the second electrode 120.
[0057] In this embodiment, the protective adhesive 160 is located on the innermost ring of the core 100, precisely attached to the boundary between the first straight area 101 and the first corner area 102. Specifically, the projection shape of the core 100 in the height direction (perpendicular to the thickness direction and the width direction of the core 100, respectively) is U-shaped, with its opening facing the center of the core 100, its bottom end covering the corner arc segment at the boundary, one end extending to the first straight area 101, and the other end extending to the second straight area 104. The protective adhesive 160 may only adhere to the non-active material area (i.e., the current collector surface) of the second electrode 120, without covering the active material layer.
[0058] In the innermost ring of the core 100, the second electrode 120 has the smallest bending curvature at the junction of the first straight area 101 and the first corner area 102. Protective adhesive 160 is applied to prevent the electrode from bending and breaking.
[0059] In some embodiments, refer to Figure 3 Along the winding direction of the core 100, at least one end of the protective adhesive 160 at opposite ends does not coincide with the projection of the end of the elongated film surface 111 of the first electrode 110 in the thickness direction of the core 100. In this embodiment, along the winding direction of the core 100, either one end of the protective adhesive 160 at opposite ends does not coincide with the projection of the end of the elongated film surface 111 of the first electrode 110 in the thickness direction of the core 100, or both ends of the protective adhesive 160 and the end of the elongated film surface 111 of the first electrode 110 do not coincide with each other in the thickness direction of the core 100. This structural arrangement allows the end of the elongated film surface 111 of the first electrode 110 to be staggered with at least one end of the protective adhesive 160 at opposite ends, preventing them from stacking.
[0060] When the end of the elongated film 111 of the first electrode 110 is offset from one end of the protective adhesive 160 and not stacked, the thickness of the cell can be reduced by the thickness of one adhesive strip at the corresponding position of the end region of the elongated film 111 of the first electrode 110. When both ends of the elongated film 111 of the first electrode 110 and the protective adhesive 160 are offset from each other and not stacked, the thickness of the adhesive strip can be reduced at the corresponding position of the end region of the elongated film 111 of the first electrode 110. Reducing the cell thickness increases the battery energy density.
[0061] In some embodiments, the thickness of the long film surface 111 of the first electrode 110 is less than or equal to the thickness of the short film surface 112 of the first electrode 110. In this embodiment, the thickness of the long film surface 111 of the first electrode 110 may be less than the thickness of the short film surface 112 of the first electrode 110, or the thickness of the long film surface 111 of the first electrode 110 may be equal to the thickness of the short film surface 112 of the first electrode 110. In other embodiments, the thickness of the long film surface 111 of the first electrode 110 may also be greater than the thickness of the short film surface 112 of the first electrode 110.
[0062] Reference Figure 1 Optionally, one end of the diaphragm 130 is located at the innermost ring of the core 100, and the other end of the diaphragm 130 is located at the outermost ring of the core 100. In this embodiment, one end of the diaphragm 130 is located at the innermost ring of the core 100, which serves to insulate the first electrode 110 and the second electrode 120, reducing the probability of short circuit between the first electrode 110 and the second electrode 120. The other end of the diaphragm 130 is located at the outermost ring of the core 100, which serves to protect and insulate the first electrode 110, preventing damage to the surface of the first electrode 110.
[0063] This utility model embodiment also proposes a battery, which includes a casing and a battery cell as described in the foregoing embodiments, with the battery cell disposed within the casing. The specific structure of the battery cell is the same as described in the foregoing embodiments. Since this battery adopts all the technical solutions of all the foregoing embodiments, it possesses at least all the technical effects brought about by the technical solutions of the foregoing embodiments, and will not be described in detail here. The battery can be a lithium battery.
[0064] The above description is only a part or preferred embodiment of this utility model. Neither the text nor the drawings should limit the scope of protection of this utility model. All equivalent structural transformations made using the content of this utility model specification and drawings under the overall concept of this utility model, or direct / indirect applications in other related technical fields, are included within the scope of protection of this utility model.
Claims
1. A battery cell, characterized in that, It includes a first electrode (110), a second electrode (120), and a diaphragm (130), wherein the second electrode (120) has the opposite polarity to the first electrode (110); The first electrode (110), the diaphragm (130) and the second electrode (120) are stacked and wound together to form a core (100), and the first electrode (110) has a long film surface (111) and a short film surface (112) on both sides along its thickness direction; In the winding direction of the core (100), the tail of the second electrode (120) extends beyond the end of the long film surface (111) and the end of the short film surface (112) of the first electrode (110), respectively. The distance between the end of the long film surface (111) of the first electrode (110) and the tail of the second electrode (120) is L1, and the distance between the end of the short film surface (112) of the first electrode (110) and the tail of the second electrode (120) is L2, satisfying: 0 < L1 < L2.
2. The battery cell according to claim 1, characterized in that, The core (100) has a first straight area (101), a first corner area (102), a second straight area (104) and a second corner area (103) arranged sequentially along its winding direction. In the width direction of the core (100), the first corner area (102) and the second corner area (103) are arranged opposite to each other at both ends of the first straight area (101) and the second straight area (104). The end of the long film surface (111) of the first electrode (110), the end of the short film surface (112) of the first electrode (110) and the tail of the second electrode (120) are all located in the first straight area (101) and are adjacent to the first corner area (102).
3. The battery cell according to claim 2, characterized in that, It also includes a first finishing adhesive (140), the head of which is bonded to the end of the short film surface (112) of the first electrode (110), and the tail of which extends to the first corner area (102).
4. The battery cell according to claim 3, characterized in that, In the winding direction of the core (100), the distance between the tail of the first finishing adhesive (140) and the end of the first straight area (101) near the first corner area (102) is L3, and the maximum arc length of the first corner area (102) is L4, satisfying: 0 < L3 < 1 / 2L4.
5. The battery cell according to claim 3 or 4, characterized in that, It also includes a second finishing adhesive (150), the head of which is located in the first flat area (101), the head of which is bonded to the winding end of the first electrode (110), and the second finishing adhesive (150) surrounds the first corner area (102), and the tail of which extends to the second flat area (104).
6. The battery cell according to claim 5, characterized in that, The portion of the first finishing adhesive (140) covering the end of the short film surface (112) of the first electrode (110) and the portion of the second finishing adhesive (150) covering the winding end of the first electrode (110) do not overlap in the projection of the core (100) in the thickness direction.
7. The battery cell according to claim 2, characterized in that, It also includes a protective adhesive (160), which is disposed on the innermost ring of the core (100); The protective adhesive (160) is located at the junction of the first straight area (101) and the first corner area (102), and its projection shape in the height direction of the core (100) is U-shaped. The protective adhesive (160) is bonded to the second electrode (120).
8. The battery cell according to claim 7, characterized in that, Along the winding direction of the core (100), at least one end of the protective adhesive (160) at opposite ends does not coincide with the projection of the end of the elongated film surface (111) of the first electrode (110) in the thickness direction of the core (100).
9. The battery cell according to claim 1, characterized in that, The thickness of the long film surface (111) of the first electrode (110) is less than or equal to the thickness of the short film surface (112) of the first electrode (110).
10. A battery, characterized in that, It includes a housing and a battery cell as described in any one of claims 1 to 9, wherein the battery cell is disposed in the housing.