Negative plate and battery

Abstract

The utility model belongs to the technical field of batteries, and particularly relates to a negative plate and a battery, the negative plate comprises a negative plate body, the negative plate body comprises a plurality of straight areas and a plurality of bent areas along the winding direction of the negative plate body, the plurality of straight areas and the plurality of bent areas are alternately arranged in sequence, and the plurality of straight areas and the plurality of bent areas are arranged in the winding direction of the negative plate body. A light curing adhesive layer is arranged on at least one bending area; under the negative pressure condition, the light curing adhesive layer can infiltrate the bending area of the negative plate body, and after the light curing adhesive layer is cured, the coating of the bending area of the negative plate body effectively has better cohesive force, adhesive force and toughness, and in the subsequent hot-pressing and charging circulation process, the bending area of the negative plate body is not damaged. The coating of the bending area of the negative plate body has better bending resistance, so that the conditions of coating stripping, fragmentation and powder falling caused by stress change of the bending area of the negative plate body are avoided, lithium precipitation at the corner position of a battery cell is avoided, the performance of the battery is further improved, and the service life of the battery is prolonged.

Description

Technical Field

[0001] The utility model belongs to the technical field of batteries, and in particular relates to a negative electrode sheet and a battery. Background Art

[0002] As a new type of secondary battery, lithium-ion battery has the advantages of high energy density and power density, high operating voltage, light weight, small size, long cycle life, good safety, and green environmental protection. It has broad application prospects in portable appliances, power tools, large-scale energy storage, electric transportation power supply, etc.

[0003] At present, batteries usually use wound-type cells. Wound-type cells generally need to be hot-pressed to convert the loose structure into a compact structure. However, during the hot-pressing process, the coating is easily peeled off at the bend of the negative electrode, resulting in lithium deposition at the corners of the cell during the subsequent charging cycle, which in turn affects the battery life. Utility Model Content

[0004] The purpose of the utility model is to provide a negative electrode sheet in view of the deficiencies in the prior art, which solves the technical problem in the prior art that the coating is easily peeled off at the bend of the negative electrode sheet during the hot pressing process, resulting in lithium deposition at the corners of the battery during subsequent charging cycles.

[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0006] A negative electrode sheet comprises a negative electrode sheet body. Along the winding direction of the negative electrode sheet body, the negative electrode sheet body comprises a plurality of straight areas and a plurality of bending areas. The plurality of straight areas and the plurality of bending areas are alternately arranged in sequence, and a photocurable adhesive layer is arranged on at least one of the bending areas.

[0007] Preferably, along the winding direction of the negative electrode sheet body, the photocurable adhesive layer is arranged on the inner surface of the bending area.

[0008] Preferably, the photocurable adhesive layer is arranged on the bending area of ​​the negative electrode sheet body close to the inner circle of the battery cell.

[0009] Preferably, the negative electrode sheet body comprises a current collector and an active material layer, the active material layer is arranged on the current collector, and the photocurable adhesive layer is arranged on the active material layer in the bending area.

[0010] Preferably, a groove is provided on the active material layer in the bending area, and the photocurable adhesive layer is provided in the groove.

[0011] Preferably, the thickness of the photocurable adhesive layer is less than or equal to the depth of the groove.

[0012] Preferably, the orthographic projection area of ​​the photocurable adhesive layer in the bending zone is less than or equal to the area of ​​the bending zone.

[0013] Preferably, the width of the photocurable adhesive layer is 1 to 5 mm.

[0014] Preferably, along the winding direction of the negative electrode sheet body, at least two of the oppositely disposed bending regions are provided with the photocurable adhesive layer.

[0015] Another object of the present invention is to provide a battery, comprising a battery cell, wherein the battery cell comprises a positive electrode sheet, a separator and the negative electrode sheet as described above in the specification, wherein the positive electrode sheet, the separator and the negative electrode sheet are stacked and wound in sequence to form the battery cell.

[0016] Compared with the prior art, the beneficial effects achieved by the utility model are:

[0017] The negative electrode sheet of the utility model is provided with a negative electrode sheet body, wherein the negative electrode sheet body includes a straight area and a bending area, wherein the straight area is used to correspond to the straight part of the battery cell, and the bending area is used to correspond to the corner of the battery cell. Since a photocuring adhesive layer is provided on the bending area of ​​the negative electrode sheet body, the photocuring adhesive layer can infiltrate the bending area of ​​the negative electrode sheet body under negative pressure conditions, and after the photocuring adhesive layer is cured, the coating of the bending area of ​​the negative electrode sheet body is effectively made to have better cohesion, adhesion and toughness. In the subsequent hot pressing and charging cycle process, the coating of the bending area of ​​the negative electrode sheet body has better anti-bending ability, thereby avoiding the coating peeling and cracking and powdering of the bending area of ​​the negative electrode sheet body due to stress changes, thereby avoiding lithium deposition at the corner of the battery cell, thereby improving the performance of the battery and extending the service life of the battery.

[0018] Additional aspects and advantages of the present invention will be given in part in the following description, and in part will become apparent from the following description, or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0020] Figure 1 It is a structural schematic diagram of the battery cell of the utility model.

[0021] Figure 2 This is one of the structural schematic diagrams of the negative electrode sheet body of the utility model.

[0022] Figure 3 This is the second structural schematic diagram of the negative electrode sheet body of the utility model.

[0023] The reference numerals are described as follows:

[0024] 100, battery cell; 101, positive electrode sheet; 102, negative electrode sheet;

[0025] 10. Negative electrode body; 11. Straight area; 12. Bending area; 123. Groove; 13. Photocuring layer; 14. Current collector; 15. Active material layer;

[0026] a. The length of the photocuring adhesive layer; b. The width of the photocuring adhesive layer; c. The length of the bending zone; d. The width of the bending zone. DETAILED DESCRIPTION

[0027] For example, certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that hardware manufacturers may use different terms to refer to the same component. This specification and claims do not use differences in names as a way to distinguish components, but use differences in the functions of components as the criteria for distinction. For example, "including" mentioned throughout the specification and claims is an open term, so it should be interpreted as "including but not limited to". "Approximately" means that within an acceptable error range, those skilled in the art can solve technical problems within a certain error range and basically achieve technical effects.

[0028] Furthermore, the terms “first”, “second”, etc. are used for descriptive purposes only and are not to be understood as indicating or implying relative importance.

[0029] In the utility model, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the utility model can be understood according to the specific circumstances.

[0030] The following will be combined with the attached Figures 1 to 3 The technical solutions in the embodiments of the utility model are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of them. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0031] See also Figures 1 to 3The battery of the embodiment of the utility model includes a shell and a battery cell 100, and the battery cell 100 is arranged in the shell.

[0032] It should be noted that the battery can be one or more. If there are multiple batteries, the multiple batteries can be connected in series, in parallel, or in mixed connection. Mixed connection means that multiple batteries are connected in series and in parallel. Multiple batteries can be directly connected in series, in parallel, or in mixed connection to form a whole; of course, multiple batteries can also be connected in series, in parallel, or in mixed connection to form a battery module, and multiple battery modules can then be connected in series, in parallel, or in mixed connection to form a whole.

[0033] The battery cell 100 of the embodiment of the present invention comprises a positive electrode sheet 101 , a negative electrode sheet 102 and a separator. The positive electrode sheet 101 , the separator and the negative electrode sheet 102 are sequentially stacked and wound to form the battery cell 100 .

[0034] See also Figures 1 to 3 The negative electrode sheet 102 of the embodiment of the utility model includes a negative electrode sheet body 10. Along the winding direction of the negative electrode sheet body 10, the negative electrode sheet body 10 includes a plurality of straight areas 11 and a plurality of bending areas 12. The plurality of straight areas 11 and the plurality of bending areas 12 are alternately arranged in sequence, and a photocurable adhesive layer 13 is arranged on at least one of the bending areas 12.

[0035] Compared with the prior art, the negative electrode sheet 102 of the present invention is provided with a negative electrode sheet body 10, wherein the negative electrode sheet body 10 includes a straight area 11 and a bending area 12, wherein the straight area 11 is used to correspond to the straight portion of the battery cell 100, and the bending area 12 is used to correspond to the corner of the battery cell 100. Since a photocurable adhesive layer 13 is provided on the bending area 12 of the negative electrode sheet body 10, the photocurable adhesive layer 13 can infiltrate the bending area 12 of the negative electrode sheet body 10 under negative pressure conditions, and the photocurable adhesive layer 13 can infiltrate the bending area 12 of the negative electrode sheet body 10 under negative pressure conditions, and the photocurable adhesive layer 13 can infiltrate the bending area 12 of the negative electrode sheet body 10 under negative pressure conditions. After curing, the coating of the bending area 12 of the negative electrode sheet body 10 effectively has better cohesion, adhesion and toughness. In the subsequent hot pressing and charging cycle process, the coating of the bending area 12 of the negative electrode sheet body 10 has better anti-bending ability, which prevents the coating from peeling off and breaking and powdering in the bending area 12 of the negative electrode sheet body 10 due to stress changes, thereby avoiding lithium deposition at the corner of the battery cell 100, thereby improving the performance of the battery and extending the service life of the battery.

[0036] In some embodiments, along the winding direction of the negative electrode sheet body 10 , the photocurable adhesive layer 13 is disposed on the inner surface of the bending region 12 .

[0037] The inventors found that after the battery is charged and cycled, the inner side of the bending area 12 is prone to coating peeling and breaking and powdering, that is, lithium deposition is prone to occur on the inner side of the bending area 12. Therefore, by setting the photocurable adhesive layer 13 on the inner surface of the bending area 12, the coating of the bending area 12 of the negative electrode sheet body 10 has better anti-bending ability, avoiding the coating peeling and breaking and powdering of the bending area 12 of the negative electrode sheet body 10 due to stress changes, thereby avoiding lithium deposition at the corner of the battery cell 100.

[0038] In some embodiments, the photocurable adhesive layer 13 is disposed on the bending area 12 of the negative electrode body close to the inner circle of the battery cell 100. Since the curvature of the bending area 12 of the negative electrode body closer to the outer circle of the battery cell 100 is greater, the bending degree is smaller, and the coating peeling and breaking and powdering are less likely to occur, and the curvature of the bending area 12 of the negative electrode body closer to the inner circle of the battery cell 100 is smaller, the bending degree is greater, and the coating peeling and breaking and powdering are more likely to occur. Therefore, the photocurable adhesive layer 13 is disposed on the bending area 12 of the negative electrode body close to the inner circle of the battery cell 100, so that the coating of the bending area 12 of the negative electrode sheet body 10 has better anti-bending ability, avoiding the coating peeling and breaking and powdering of the bending area 12 of the negative electrode sheet body 10 due to changes in stress, thereby avoiding lithium deposition at the corner of the battery cell 100.

[0039] See also Figures 2-3 In some embodiments, the negative electrode sheet body 10 includes a current collector 14 and an active material layer 15 , the active material layer 15 is disposed on the current collector 14 , and the photocurable adhesive layer 13 is disposed on the active material layer 15 in the bending region 12 .

[0040] By using the current collector 14 and the active material layer 15 in combination, the active material layer 15 is arranged on the current collector 14, and the structure of the negative electrode sheet body 10 is effectively arranged. Since the photocurable adhesive layer 13 is arranged on the active material layer 15 of the bending area 12, the porosity of the negative electrode sheet 102 is utilized to allow the photocurable adhesive layer 13 to infiltrate the bending area 12 of the negative electrode sheet body 10, and after the photocurable adhesive layer 13 is cured, it not only effectively makes the coating of the bending area 12 of the negative electrode sheet body 10 have better cohesion, adhesion and toughness, and avoids lithium deposition at the corner position of the battery cell 100, but also does not increase the thickness of the active material layer 15, thereby improving the performance of the battery.

[0041] See also Figure 3 In some embodiments, a groove 123 is provided on the active material layer 15 of the bending area 12, and the photocurable adhesive layer 13 is provided in the groove 123. By providing the groove 123, the photocurable adhesive layer 13 is provided in the groove 123, which effectively assists the positioning of the photocurable adhesive layer 13 and avoids increasing the thickness of the active material layer 15.

[0042] In some embodiments, the thickness of the photocurable adhesive layer 13 is less than or equal to the depth of the groove 123. By setting the thickness of the photocurable adhesive layer 13, the thickness of the photocurable adhesive layer 13 is less than or equal to the depth of the groove 123, so that the photocurable adhesive layer 13 infiltrates the bending area 12 of the negative electrode sheet body 10 and occupies less space in the thickness direction of the negative electrode body, effectively improving the performance of the battery.

[0043] In some embodiments, the orthographic projection area of ​​the photocurable adhesive layer 13 in the bending zone 12 is less than or equal to the area of ​​the bending zone 12. By the orthographic projection area of ​​the photocurable adhesive layer 13 in the bending zone 12, the orthographic projection area of ​​the photocurable adhesive layer 13 in the bending zone 12 is less than or equal to the area of ​​the bending zone 12, so that the photocurable adhesive layer 13 can fully cover the position where the negative electrode body is prone to lithium deposition, and can better avoid lithium deposition at the corners of the battery cell 100.

[0044] Specifically, the length a of the photocurable adhesive layer 13 is less than or equal to the length c of the bending zone 12 , and / or the width b of the photocurable adhesive layer 13 is less than or equal to the width d of the bending zone 12 .

[0045] Further, the width b of the photocurable adhesive layer 13 is 1 to 5 mm. For example, the width b of the photocurable adhesive layer 13 is 1 mm, 1.2 mm, 1.5 mm, 2 mm, 2.4 mm, 2.8 mm, 3 mm, 3.5 mm, 3.8 mm, 4 mm, 4.2 mm, 4.6 mm or 5 mm, but is not limited to the listed values, and other values ​​within the numerical range are also applicable.

[0046] In some embodiments, along the winding direction of the negative electrode sheet body 10, at least two of the oppositely disposed bending regions 12 are provided with the photocurable adhesive layer 13. By providing the photocurable adhesive layer 13 in at least two oppositely disposed bending regions 12, the coating in the bending region 12 of the negative electrode sheet body 10 has better anti-bending ability, thereby preventing the coating from peeling off and breaking and powdering in the bending region 12 of the negative electrode sheet body 10 due to stress changes, thereby preventing lithium deposition at the corners of the battery cell 100.

[0047] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention.

Claims

1. A negative electrode sheet, characterized in that: The invention comprises a negative electrode sheet body (10), wherein along the winding direction of the negative electrode sheet body (10), the negative electrode sheet body (10) comprises a plurality of straight regions (11) and a plurality of bent regions (12), the plurality of straight regions (11) and the plurality of bent regions (12) are arranged alternately in sequence, and a photocurable adhesive layer (13) is arranged on at least one of the bent regions (12).

2. The negative electrode sheet according to claim 1, characterized in that: Along the winding direction of the negative electrode sheet body (10), the photocurable adhesive layer (13) is arranged on the inner surface of the bending area (12).

3. The negative electrode sheet according to claim 1, characterized in that: The photocurable adhesive layer (13) is arranged on the bending area (12) of the negative electrode sheet body (10) close to the inner circle of the battery cell (100).

4. The negative electrode sheet according to claim 1, characterized in that: The negative electrode sheet body (10) comprises a current collector (14) and an active material layer (15), wherein the active material layer (15) is arranged on the current collector (14), and the photocurable adhesive layer (13) is arranged on the active material layer (15) in the bending area (12).

5. The negative electrode sheet according to claim 4, characterized in that: A groove (123) is provided on the active material layer (15) of the bending area (12), and the photocurable adhesive layer (13) is arranged in the groove (123).

6. The negative electrode sheet according to claim 5, characterized in that: The thickness of the photocurable adhesive layer (13) is less than or equal to the depth of the groove (123).

7. The negative electrode sheet according to claim 1, characterized in that: The orthographic projection area of ​​the photocurable adhesive layer (13) in the bending zone (12) is less than or equal to the area of ​​the bending zone (12).

8. The negative electrode sheet according to claim 1, characterized in that: The width (b) of the photocurable adhesive layer (13) is 1 to 5 mm.

9. The negative electrode sheet according to claim 1, characterized in that: Along the winding direction of the negative electrode sheet body (10), at least two of the bending regions (12) arranged opposite to each other are provided with the photocurable adhesive layer (13).

10. A battery, characterized in that: A battery cell (100), the battery cell (100) comprising a positive electrode sheet (101), a separator and a negative electrode sheet (102) according to any one of claims 1 to 9, the positive electrode sheet (101), the separator and the negative electrode sheet (102) being stacked and wound in sequence to form the battery cell (100).

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