Electrode assembly and battery

Abstract

The utility model provides an electrode assembly and a battery, the electrode assembly comprises a winding body, the winding body is formed by winding a pole piece and a diaphragm which are stacked, the winding body is provided with a straight area and a bending area, the ending end of the pole piece is located in the bending area, the outer surface of the winding body is attached with a termination adhesive tape along the winding direction, and the termination adhesive tape is attached to the outer surface of the winding body. The terminating adhesive tape is wound on the winding body by one circle, the two ends of the terminating adhesive tape are overlapped, and the length of the overlapped area in the winding direction is smaller than or equal to 5% of the perimeter of the winding body in the winding direction. The electrode assembly and the battery provided by the utility model are simple in structure and convenient to manufacture, the winding body can be effectively bound, the pole pieces are prevented from loosening, and the cycle performance of the battery is improved.

Description

Technical Field

[0001] The present application relates to the technical field of energy storage, and particularly relates to an electrode assembly and a battery. Background Art

[0002] Currently, lithium-ion batteries are developing rapidly in the fields of electric vehicles and large-scale energy storage. The electrode assembly of a lithium-ion battery is formed by winding or laminating a positive electrode sheet, a negative electrode sheet, and a separator. Among them, the winding method has high production capacity and yield, and is widely used in battery production. After the electrode assembly is wound, it is usually necessary to attach a tape for fixation. However, the existing tape attachment method has limited binding effect on the electrode sheet and also affects the battery cycle performance. Therefore, there is an urgent need for an electrode assembly that can improve the tape attachment effect. Summary of the Utility Model

[0003] In view of this, the purpose of the present application is to provide an electrode assembly and a battery to solve the related problems mentioned in the background art.

[0004] In the first aspect of the present application, an electrode assembly is provided, including a wound body. The wound body is formed by winding a laminated electrode sheet and a separator, and has a flat area and a bent area. The end of the electrode sheet is located in the bent area. A termination tape is attached to the outer surface of the wound body along the winding direction. The termination tape winds around the wound body for one circle, and the two ends of the termination tape overlap, and the length of the overlapping area along the winding direction is less than or equal to 5% of the circumference of the wound body along the winding direction.

[0005] Further, the electrode sheet includes a first electrode sheet and a second electrode sheet arranged in layers. The separator separates the first electrode sheet and the second electrode sheet. The wound body has two bent areas, and the end of the first electrode sheet and the end of the second electrode sheet are located in the same or different bent areas.

[0006] Further, the overlapping area of the termination tape is located in the flat area and is spaced from the bent area.

[0007] Further, the direction perpendicular to the winding direction of the wound body is the axis direction. The length of the termination tape along the axis direction is greater than the length of the electrode sheet along the axis direction and less than the length of the separator along the axis direction.

[0008] Further, a plurality of termination tapes are arranged at intervals along the axis direction of the wound body. Each termination tape winds around the wound body for one circle, and the distance between adjacent two termination tapes along the axis direction is less than or equal to 20% of the length of the wound body along the axis direction.

[0009] Further, the termination tape includes a base layer and an adhesive layer arranged in a stacked manner, and the adhesive layer is at least located in the two end regions of the base layer along the winding direction.

[0010] Further, a plurality of through holes are provided in at least a part of the termination tape.

[0011] Further, reinforcement tapes are attached to both sides of the winding body along the axial direction, and the reinforcement tapes partially overlap with the termination tape.

[0012] In a second aspect of the present application, a battery is provided, which includes a housing and the electrode assembly as described in the first aspect above disposed in the housing.

[0013] Further, a plurality of the electrode assemblies are arranged in a stacked manner, and the bonding surface between two adjacent electrode assemblies is a core bonding surface. Among two adjacent electrode assemblies, the overlapping regions of the termination tapes corresponding to each electrode assembly are all arranged towards the core bonding surface, and the orthographic projections of the two overlapping regions on the core bonding surface do not overlap.

[0014] As can be seen from the above, for the electrode assembly and the battery provided in the present application, the electrode assembly includes a winding body, which is formed by winding a stacked electrode sheet and a separator, and has a flat region and a bent region. The end portions of the electrode sheet are located in the bent region. The outer surface of the winding body is attached with a termination tape along the winding direction. The termination tape winds around the winding body for one circle, and the two ends of the termination tape overlap to ensure the binding effect on the end portions of the electrode sheet and prevent the electrode sheet from loosening, which may affect the battery performance. The length of the overlapping region of the termination tape along the winding direction is less than or equal to 5% of the circumference of the winding body along the winding direction, which can avoid the overlapping region being too long and the stress concentration region being too large, resulting in indentations during subsequent hot pressing or cold pressing of the electrode assembly and reducing the battery cycle performance. It can also avoid the overlapping region being too long and reducing the infiltration effect of the electrolyte on the electrode assembly, which may affect the battery performance. Moreover, it can avoid reducing the bonding efficiency and increasing the production cost, etc. Through testing, the cycle performance of this electrode assembly can be improved by 1.1% compared with the electrode assembly without overlapping bonding of the tape. The electrode assembly and the battery have a simple structure and are easy to manufacture, can effectively bind the winding body, prevent the electrode sheet from loosening, and improve the battery cycle performance. Description of the Drawings

[0015] In order to more clearly illustrate the technical solutions in the present application or related technologies, the following will briefly introduce the drawings required for use in the description of the embodiments or related technologies. Obviously, the drawings in the following description are only the embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0016] Figure 1 It is a schematic structural diagram of the first electrode assembly in the embodiment of the present application.

[0017] Figure 2 This is a schematic cross-sectional structure diagram of the first type of core in the embodiments of the present application.

[0018] Figure 3 This is a schematic cross-sectional structure diagram of the second type of core in the embodiments of the present application.

[0019] Figure 4 is Figure 1 a schematic top view structure diagram of the electrode assembly in

[0020] Figure 5 is Figure 1 a schematic cross-sectional structure diagram of the electrode assembly in the present application along the A-A direction.

[0021] Figure 6 This is a schematic structure diagram of the second type of electrode assembly in the embodiments of the present application.

[0022] Figure 7 is a schematic unfolded cross-sectional diagram of the termination tape.

[0023] Figure 8 This is a schematic cross-sectional structure diagram of a battery in the embodiments of the present application.

[0024] Reference numerals: 1, electrode assembly; 2, winding body; 2-1, straight region; 2-2, bending region; 2-3, electrode tab; 2-3-1, first electrode tab; 2-3-2, second electrode tab; 2-4, separator; 2-5, tab; 3, termination tape; 3-1, overlapping region; 3-2, base layer; 3-3, adhesive layer; 3-4, via hole; 4, reinforcement tape; 5, housing. Detailed implementation manners

[0025] To make the objectives, technical solutions, and advantages of the present application clearer and more understandable, the following further elaborates on the present application in detail with reference to specific embodiments and the accompanying drawings.

[0026] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present application should have the ordinary meanings understood by those of ordinary skill in the art to which the present application belongs. The "first", "second" and similar terms used in the embodiments of the present application do not denote any order, quantity or importance, but are only used to distinguish different components. Words such as "including" or "comprising" mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Upper", "lower", "left", "right", etc. are only used to represent relative positional relationships, and when the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0027] Currently, lithium-ion batteries are developing rapidly in the fields of electric vehicles and large-scale energy storage. The electrode assembly of a lithium-ion battery is formed by winding or laminating a positive electrode sheet, a negative electrode sheet, and a separator. Among them, the winding method has higher production capacity and yield and is widely used in battery production. After the electrode assembly is wound, it is usually necessary to attach a tape for fixation. However, the existing tape attachment method has limited binding effect on the electrode sheet and also affects the battery cycle performance. Therefore, there is an urgent need for an electrode assembly that can improve the tape attachment effect.

[0028] The wound electrode assembly includes a flat area and a bent area, and the end portions of the positive and negative electrode sheets of the electrode assembly can be arranged in the bent area, so as to avoid setting a flat area and generating indentations during subsequent hot pressing or cold pressing of the electrode sheets, damaging the electrode sheet structure, and reducing the battery performance. However, the end of the electrode sheet in the bent area is more likely to loosen compared to the flat area. Especially with the cyclic use of the battery, the electrode sheet expands, which will further increase the gap between the electrode sheets in the bent area, resulting in lithium deposition defects at the interface, etc., reducing the battery cycle performance.

[0029] In some technologies, a U-shaped tape is arranged at the end portion to fit the bent area, but the binding ability to the electrode assembly is limited, and the electrode sheet is still likely to loosen, reducing the battery cycle performance; in some other technologies, adhesive layers are arranged on both sides of the separator to closely fit the electrode sheet. Although the stability of the electrode sheet at the end portion is improved, the cost is also greatly increased, and due to the extensive use of the adhesive layer, the wetting effect of the electrolyte on the electrode assembly is also reduced, which will also reduce the battery cycle performance.

[0030] Hereinafter, the technical solutions of the present application will be described in detail through specific embodiments.

[0031] In some embodiments of the present application, an electrode assembly 1 is provided, as Figure 1As shown, it includes a wound body 2, which is formed by winding a stacked electrode tab 2-3 and a separator 2-4, and has a flat area 2-1 and a bent area 2-2. The starting and ending ends of the electrode tab 2-3 are located within the bent area 2-2. A termination tape 3 is attached to the outer surface of the wound body 2 along the winding direction. The termination tape 3 winds around the wound body 2 for one circle. The two ends of the termination tape 3 overlap, and the length of the overlapping area 3-1 along the winding direction is less than or equal to 5% of the circumference of the wound body 2 along the winding direction.

[0032] The electrode assembly 1 includes a wound body 2, as Figure 1 shown. In the figure, the R direction is the winding direction of the wound body 2, and the Z direction is the axis direction of the wound body 2. The structure of the wound body 2 is, for example, Figure 2 shown, and is formed by winding a stacked electrode tab 2-3 and a separator 2-4, and has a flat area 2-1 and two bent areas 2-2. The starting and ending ends of the electrode tab 2-3 are located within the bent area 2-2, and are avoided to be set in the flat area 2-1 to prevent indentations from being formed during subsequent hot pressing or cold pressing processes, which may damage the structure of the electrode tab 2-3.

[0033] As Figure 1 shown, a termination tape 3 is attached to the outer surface of the wound body 2 along the winding direction. The termination tape 3 winds around the wound body 2 for one circle. The two ends of the termination tape 3 overlap to ensure the binding effect on the starting and ending ends of the electrode tab 2-3 and prevent the electrode tab 2-3 from loosening, which may affect the battery performance.

[0034] Limited by the manufacturing process of the electrode assembly 1, the circumference of the wound body 2 along the winding direction is usually 200 mm to 350 mm. The length of the overlapping area 3-1 of the termination tape 3 along the winding direction is less than or equal to 5% of the circumference of the wound body 2 along the winding direction. For example, the length of the termination tape 3 is 1%, 2%, 3%, 4%, or 5% of the circumference of the wound body 2, etc., and is not specifically limited. This can avoid the overlapping area 3-1 being too long and the stress concentration area being too large, which may cause indentations during subsequent hot pressing or cold pressing of the electrode assembly 1 and reduce the battery cycle performance. It can also avoid the overlapping area 3-1 being too long and reducing the wetting effect of the electrolyte on the electrode assembly 1, which may affect the battery performance. It can also avoid reducing the bonding efficiency and increasing the production cost, etc.

[0035] The structure of the electrode assembly 1 is simple and easy to manufacture, and can effectively bind the wound body 2 to prevent the electrode tab 2-3 from loosening and improve the battery cycle performance. After testing, the cycle performance of this electrode assembly can be improved by 1.1% compared with the electrode assembly with non-overlapping tape bonding.

[0036] Example 1

[0037] The electrode assembly 1 includes a wound body 2. The circumference of the wound body 2 is 290 mm. A termination tape 3 is attached to the outer surface of the wound body 2 along the winding direction. The termination tape 3 winds around the wound body 2 for one circle. The two ends of the termination tape 3 overlap, and the length of the overlapping area 3-1 is 5.8 mm, which is 2% of the circumference of the wound body 2.

[0038] Example 2

[0039] The electrode assembly 1 includes a wound body 2. The circumference of the wound body 2 is 290 mm. A termination tape 3 is attached to the outer surface of the wound body 2 along the winding direction. The termination tape 3 winds around the wound body 2 for one circle. The two ends of the termination tape 3 overlap, and the length of the overlapping area 3-1 is 14.5 mm, which is 5% of the circumference of the wound body 2.

[0040] Comparative Example 1

[0041] The electrode assembly 1 includes a wound body 2. The circumference of the wound body 2 is 290 mm. A termination tape 3 is attached to the outer surface of the wound body 2 along the winding direction. The termination tape 3 winds around the wound body 2 for one circle. The two ends of the termination tape 3 overlap, and the length of the overlapping area 3-1 is 20.3 mm, which is 7% of the circumference of the wound body 2.

[0042] Comparative Example 2

[0043] The electrode assembly 1 includes a wound body 2. The circumference of the wound body 2 is 290 mm. A tape is attached to the outer surface of the wound body 2 along the winding direction. The tape winds around the wound body 2 for less than one circle. The distance between the two ends of the tape along the winding direction is 14.5 mm.

[0044] The electrode assemblies 1 of Example 1 to Example 2 and Comparative Example 1 to Comparative Example 2 were made into lithium iron phosphate batteries, and the 25°C cycle performance of the batteries was tested. The charge-discharge cycle system of 1C / 1C was adopted, and the voltage range was 2.5 V - 3.65 V. Based on the discharge capacity of the first complete charge-discharge cycle, the capacity retention rate after 1000 cycles of each scheme was statistically analyzed. The test results are shown in Table 1. After testing, the battery cycle performance of the electrode assembly 1 of Example 1 was improved by 1.1% compared with that of the electrode assembly 1 of Comparative Example 2, indicating that the overlap of the tape can improve the battery performance; the battery cycle performance of the electrode assembly 1 of Example 2 was improved by 0.7% compared with that of the electrode assembly 1 of Comparative Example 1, indicating that too long overlap of the tape will reduce the battery performance.

[0045] Table 1 Comparison table of battery cycle performance

[0046]

[0047]

[0048] In some embodiments, the electrode sheet 2-3 includes a first electrode sheet 2-3-1 and a second electrode sheet 2-3-2 which are stacked, the separator 2-4 separates the first electrode sheet 2-3-1 and the second electrode sheet 2-3-2, the winding body 2 has two bending regions 2-2, and the starting and ending ends of the first electrode sheet 2-3-1 and the starting and ending ends of the second electrode sheet 2-3-2 are located in the same or different bending regions 2-2.

[0049] The first electrode sheet 2-3-1 is, for example, a negative electrode sheet, and the second electrode sheet 2-3-2 is, for example, a positive electrode sheet, and no specific limitation is made. As Figure 2 shown, the starting and ending ends of both the first electrode sheet 2-3-1 and the second electrode sheet 2-3-2 are located in the same bending region 2-2, which is convenient for manufacturing and has low cost; as Figure 3 shown, the starting and ending end of the first electrode sheet 2-3-1 is located in one bending region 2-2, and the starting and ending end of the second electrode sheet 2-3-2 is located in another bending region 2-2, which is convenient for realizing the differential design of the electrode sheet 2-3. For example, the length of the negative electrode sheet is set to be greater than the length of the positive electrode sheet to avoid overcharging of the battery.

[0050] In some embodiments, as Figure 1 shown, the overlapping region 3-1 of the termination tape 3 is located in the straight region 2-1 and is spaced from the bending region 2-2.

[0051] As Figure 4 shown, the overlapping region 3-1 of the termination tape 3 is located in the straight region 2-1. In this way, the termination tape 3 located in the bending region 2-2 can be a single-layer tape with uniform thickness, so that the force at this place is more uniform. Compared with the overlapping region 3-1 being arranged in the bending region 2-2, stress concentration in the bending region 2-2 can be avoided, and the structural stability of the electrode sheet 2-3 at the starting and ending ends can be reduced. Moreover, arranging the overlapping region 3-1 in the straight region 2-1 is also convenient for fitting operation and is convenient for manufacturing.

[0052] The overlapping region 3-1 is spaced from the bending region 2-2, further avoiding the influence of stress concentration in the overlapping region 3-1 on the electrode sheet 2-3 in the bending region 2-2, improving the structural stability and the battery performance. The spacing distance is, for example, 30 mm, and no specific limitation is made.

[0053] In some embodiments, as Figure 5 shown, the direction perpendicular to the winding direction of the winding body 2 is the axial direction, the length of the termination tape 3 along the axial direction is greater than the length of the electrode sheet 2-3 along the axial direction, and is less than the length of the separator 2-4 along the axial direction.

[0054] As Figure 5As shown, the length of the termination tape 3 in the axial direction is greater than the length of the electrode tab 2-3, that is, the termination tape 3 can cover the electrode tab 2-3 to ensure the binding effect on the electrode tab 2-3; the length of the termination tape 3 in the axial direction is less than the length of the separator 2-4 to prevent the edge of the separator 2-4 from collapsing towards the tab 2-5 of the electrode assembly 1, exposing the electrode tab 2-3 from the electrode assembly 1 and reducing the battery performance; the distance between the edge of the separator 2-4 and the edge of the termination tape 3 is, for example, 5 mm, and the distance between the edge of the termination tape 3 and the edge of the electrode tab 2-3 is, for example, 5 mm, which is not specifically limited to ensure the battery performance.

[0055] In some embodiments, as Figure 6 shown, a plurality of the termination tapes 3 are arranged at intervals in the axial direction of the winding body 2, each of the termination tapes 3 winds around the winding body 2 for one circle, and the distance between two adjacent termination tapes 3 in the axial direction is less than or equal to 20% of the length of the winding body 2 in the axial direction.

[0056] As Figure 6 shown, two spaced termination tapes 3 are arranged at intervals in the axial direction of the winding body 2. By arranging the spaced termination tapes 3, the area of the termination tape 3 covering the separator 2-4 can be reduced, the wetting effect of the electrolyte on the electrode assembly 1 can be improved, the heat dissipation performance of the electrode assembly 1 can be improved, and thus the cycle performance of the battery can be enhanced.

[0057] The distance between two adjacent termination tapes 3 in the axial direction is less than or equal to 20% of the length of the winding body 2 in the axial direction. For example, the distance between the termination tapes 3 is 1%, 5%, 10%, 15% or 20% of the length of the winding body 2, etc., which is not specifically limited. To avoid too large a distance, the binding effect on the electrode tab 2-3 in the bending area 2-2 is reduced, resulting in lithium deposition defects at the interface, etc., and reducing the battery cycle performance.

[0058] Example 3

[0059] The electrode assembly 1 includes a winding body 2 with a circumference of 300 mm and a length of 90 mm in the axial direction. One termination tape 3 is attached along the axial direction of the winding body 2. The termination tape 3 winds around the winding body 2 for one circle, and the two ends of the termination tape 3 overlap, and the length of the overlapping area 3-1 is 6 mm.

[0060] Example 4

[0061] The electrode assembly 1 includes a winding body 2 with a circumference of 300 mm and a length of 90 mm in the axial direction. Two termination tapes 3 are attached along the axial direction of the winding body 2. The interval between the two termination tapes 3 is 9 mm, which is 10% of the length of the winding body 2. Each termination tape 3 winds around the winding body 2 for one circle, and the two ends of the termination tape 3 overlap, and the length of the overlapping area 3-1 is 6 mm.

[0062] Example 5

[0063] The electrode assembly 1 includes a wound body 2. The circumference of the wound body 2 is 300 mm, the length of the wound body 2 in the axial direction is 90 mm. Two termination tapes 3 are attached along the axial direction of the wound body 2. The interval between the two termination tapes 3 is 18 mm, which is 20% of the length of the wound body 2. The termination tape 3 winds around the wound body 2 for one circle. The two ends of the termination tape 3 overlap, and the length of the overlapping area 3-1 is 6 mm.

[0064] Comparative Example 3

[0065] The electrode assembly 1 includes a wound body 2. The circumference of the wound body 2 is 300 mm, the length of the wound body 2 in the axial direction is 90 mm. Two termination tapes 3 are attached along the axial direction of the wound body 2. The interval between the two termination tapes 3 is 27 mm, which is 30% of the length of the wound body 2. The termination tape 3 winds around the wound body 2 for one circle. The two ends of the termination tape 3 overlap, and the length of the overlapping area 3-1 is 6 mm.

[0066] The electrode assemblies 1 of Examples 3 to 5 and Comparative Example 3 were fabricated into lithium iron phosphate batteries, and the 25°C cycle performance of the batteries was tested. The charge-discharge cycle regime of 1C / 1C was adopted, and the voltage range was 2.5 V - 3.65 V. Based on the discharge capacity of the first complete charge-discharge cycle, the capacity retention rate after 1000 cycles of each scheme was statistically analyzed. The test results are shown in Table 2. After testing, the battery cycle performance of the electrode assembly 1 of Example 4 was improved by 0.5% compared with that of the electrode assembly 1 of Example 3, indicating that the tape with a set interval can improve the battery performance; the battery cycle performance of the electrode assembly 1 of Example 5 was improved by 0.7% compared with that of the electrode assembly 1 of Comparative Example 3, indicating that too large a tape interval will reduce the battery performance.

[0067] Table 2 Battery Cycle Performance Comparison Table

[0068] Group Spacing ratio of the termination tape Capacity retention rate after 1000 cycles Example 3 - 92.8％ Example 4 10％ 93.3％ Example 5 20％ 93.8％ Comparative Example 3 30％ 93.1％

[0069] In some embodiments, as Figure 7 shown, the termination tape 3 includes a base layer 3-2 and an adhesive layer 3-3 which are stacked, and the adhesive layer 3-3 is at least located in the two end regions of the base layer 3-2 along the winding direction.

[0070] The material of the base layer 3-2 is, for example, polyethylene terephthalate (PET) or oxidized polyethylene wax (OPE), etc., which is used to provide a base and binding force. The adhesive layer 3-3 is arranged facing the separator 2-4, and its material is, for example, acrylic, rubber or silicone, etc., which is used for bonding; the adhesive layer 3-3 can completely cover the base layer 3-2, so that the base layer 3-2 and the separator 2-4 are completely separated by the adhesive layer 3-3, which is convenient for manufacturing; the adhesive layer 3-3 can also partially cover the base layer 3-2, as Figure 7 shown, the adhesive layer 3-3 is provided only in the two end regions of the base layer 3-2 along the winding direction. In this way, on the basis of ensuring the overlapping bonding of the termination tape 3, there is only a partial area with the adhesive layer 3-3 between the base layer 3-2 and the separator 2-4, and the base layer 3-2 and the separator 2-4 in other areas are in direct contact, thereby reducing the amount of the adhesive layer 3-3 used, reducing costs, and improving the infiltration effect and heat dissipation effect, and avoiding the generation of bubbles during the bonding of the termination tape 3 when the adhesive layer 3-3 is provided in the whole layer, which reduces the battery performance.

[0071] In some embodiments, as Figure 6 shown, a plurality of through holes 3-4 are provided in at least a part of the termination tape 3.

[0072] As Figure 6 shown, a plurality of circular through holes 3-4 are provided on the termination tape 3, which can reduce the area of the termination tape 3 covering the separator 2-4, improve the infiltration effect and heat dissipation performance. The through holes 3-4 are arranged in the straight section 2-1 instead of the bent section 2-2 to avoid affecting the binding effect of the termination tape 3 on the bent section 2-2.

[0073] In some embodiments, as Figure 1 shown, reinforcing tapes 4 are attached to both sides of the winding body 2 along the axial direction, and the reinforcing tapes 4 partially overlap with the termination tape 3.

[0074] As Figure 6 shown, six reinforcing tapes 4 are attached to both sides of the winding body 2 along the axial direction. The reinforcing tapes 4 are U-shaped tapes, which can bond the front and back large surfaces of the winding body 2 at the same time. Four of the reinforcing tapes 4 are arranged at the corners of the straight section 2-1, and the other two reinforcing tapes 4 are arranged in the middle section of the straight section 2-1 to further reinforce the winding body 2; the reinforcing tapes 4 avoid the tabs 2-5 of the electrode assembly 1, and the reinforcing tapes 4 partially overlap with the termination tape 3 to improve the bonding stability of the termination tape 3.

[0075] In some embodiments of the present application, a battery is provided, as Figure 8 shown, which includes a housing 5 and the electrode assembly 1 as described in any of the above embodiments arranged in the housing 5.

[0076] The battery includes a housing 5, in which an electrode assembly 1 is disposed and electrolyte is filled. The battery can be applied to electrical devices, such as mobile computers, portable phones, memory cards, liquid crystal TVs, automobiles, motorcycles, electrodes, clocks, cameras, etc. that contain the battery. Specifically, there is no limitation. This battery has good stability and strong cycle performance.

[0077] In some embodiments, as Figure 8 shown, there are multiple electrode assemblies 1 which are stacked. The joint surface between two adjacent electrode assemblies 1 is the core joint surface. In two adjacent electrode assemblies 1, the overlapping area 3-1 of the termination tape 3 corresponding to each electrode assembly 1 faces the core joint surface, and the orthographic projections of the two overlapping areas 3-1 on the core joint surface do not overlap.

[0078] As Figure 8 shown, two fitting electrode assemblies 1 are provided in the housing 5. The dotted line position in the figure represents the core joint surface. The overlapping area 3-1 of the termination tape 3 corresponding to each electrode assembly 1 faces the core joint surface, and the orthographic projections of the two overlapping areas on the core joint surface do not overlap, that is, the two overlapping areas 3-1 are arranged in a staggered manner. In this way, the cross-sectional thickness of the combined electrode assembly 1 can be reduced, the space utilization rate can be improved, the battery energy density can be increased, and compared with the case where the two overlapping areas 3-1 are overlapped, it can be avoided that the termination tape 3 in a local area is too thick, resulting in stress concentration, and bubbles are likely to be generated when the electrode tab 2-3 expands, affecting the cycle performance of the battery.

[0079] Those of ordinary skill in the art should understand that: the discussion of any above embodiment is only exemplary and is not intended to imply that the scope of the present application (including the claims) is limited to these examples; under the idea of the present application, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations in different aspects of the embodiments of the present application as described above, which are not provided in detail for the sake of brevity.

[0080] In addition, in the case of elaborating details to describe the exemplary embodiments of the present application, it is obvious to those skilled in the art that the present application embodiments can be implemented without these details or with changes in these details. Therefore, these descriptions should be considered illustrative rather than restrictive.

[0081] Although the present application has been described in combination with the embodiments of the present application, according to the previous description, many substitutions, modifications and variations of these embodiments will be obvious to those of ordinary skill in the art.

[0082] Embodiments of the present application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present application shall be included within the protection scope of the present application.

Claims

1. An electrode assembly, characterized in that: The invention comprises a winding body, which is formed by winding stacked pole pieces and diaphragms, and has a straight area and a bending area. The tail end of the pole piece is located in the bending area. The outer surface of the winding body is adhered with a termination tape along the winding direction. The termination tape is wound around the winding body for one circle. The two ends of the termination tape overlap, and the length of the overlapping area along the winding direction is less than or equal to 5% of the circumference of the winding body along the winding direction.

2. The electrode assembly according to claim 1, characterized in that: The pole piece includes a first pole piece and a second pole piece which are stacked, the diaphragm separates the first pole piece and the second pole piece, the winding body has two bending regions, and the tail end of the first pole piece and the tail end of the second pole piece are located in the same or different bending regions.

3. The electrode assembly according to claim 1, characterized in that: The overlapping area of ​​the termination tape is located in the straight area and is spaced apart from the bending area.

4. The electrode assembly according to claim 1, characterized in that: The direction of the winding body perpendicular to the winding direction is the axial direction, and the length of the terminating tape along the axial direction is greater than the length of the pole piece along the axial direction, and is less than the length of the diaphragm along the axial direction.

5. The electrode assembly according to claim 1, characterized in that: The winding body is provided with a plurality of terminating tapes at intervals along the axial direction, each terminating tape is wound around the winding body once, and the spacing between two adjacent terminating tapes along the axial direction is less than or equal to 20% of the length of the winding body along the axial direction.

6. The electrode assembly according to claim 1, characterized in that: The termination tape comprises a base layer and an adhesive layer which are stacked, and the adhesive layer is at least located at two end regions of the base layer along the winding direction.

7. The electrode assembly according to claim 1, characterized in that: A plurality of vias are provided in at least a portion of the termination tape.

8. The electrode assembly according to claim 1, characterized in that: Reinforcing tapes are attached to both sides of the winding body along the axial direction, and the reinforcing tapes partially overlap with the terminating tapes.

9. A battery, characterized in that: The invention comprises a shell and an electrode assembly according to any one of claims 1 to 8 arranged in the shell.

10. The battery according to claim 9, characterized in that The electrode assemblies are multiple and stacked, and the bonding surfaces of two adjacent electrode assemblies are core-joining surfaces. In the two adjacent electrode assemblies, the overlapping areas of the termination tapes corresponding to each electrode assembly are arranged toward the core-joining surface, and the orthographic projections of the two overlapping areas on the core-joining surface do not overlap.

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