Diaphragm and battery

Abstract

The utility model discloses a diaphragm and battery, diaphragm includes base film and adhesive layer, and base film is equipped with the main body area and the bending area of connection, adhesive layer is located at the surface of at least one side of base film, and adhesive layer includes the multiple glue point of dot matrix distribution, and the unit glue coating amount of bending area is less than the unit glue coating amount of main body area, through with diaphragm is divided into the bending area of needing bending and the main body area of not needing bending, the unit glue coating amount of bending area is selectively reduced, and then the influence of the glue of bending area in the bending process of bending area to diaphragm uplift is reduced, thereby reducing the uplift of diaphragm, avoiding diaphragm and pole piece separation, effectively improve the performance of battery cell, and avoid the continuous distribution of adhesive layer in the bending area, improve the infiltration effect of electrolyte, avoid pole piece lithium analysis.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to a separator and a battery. Background Technology

[0002] In related technologies, the connection between the base film and ceramic layer of the separator in the battery cell is usually achieved by uniform coating. In some areas (especially the bending area of ​​the battery cell), insufficient electrolyte wetting is prone to occur, leading to lithium plating on the electrode and affecting the interface and performance of the battery cell after cycling. Utility Model Content

[0003] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a separator and battery that can reduce stress concentration in the bending area of ​​the cell by reducing the amount of adhesive applied per unit area in the bending zone, thereby reducing separator bulging, preventing electrode and separator separation, and improving cell performance.

[0004] On one hand, this utility model embodiment provides a diaphragm, comprising: The base membrane has a connected main body area and a bending area; An adhesive layer is disposed on at least one side surface of the base film. The adhesive layer includes a plurality of adhesive dots distributed in a dot matrix, and the amount of adhesive applied per unit area in the bending region is less than the amount of adhesive applied per unit area in the main body region.

[0005] According to some embodiments of the present invention, the dot matrix distribution shape of the adhesive dots on the main body area is the same as the dot matrix distribution shape of the adhesive dots on the bending area; The distribution density of adhesive dots on the main body area is greater than the distribution density of adhesive dots on the bending area. And / or, The amount of adhesive applied to the adhesive dots on the main body area is greater than the amount of adhesive applied to the adhesive dots on the bending area.

[0006] According to some embodiments of the present invention, the amount of adhesive applied to a single adhesive dot in the bending area is 0.3 to 0.5 times the amount of adhesive applied to a single adhesive dot in the main body area.

[0007] According to some embodiments of the present invention, the smallest unit of the dot matrix distribution of the adhesive dots is a regular polygon, and the adhesive dots are located at the endpoints of the regular polygon.

[0008] According to some embodiments of the present invention, the smallest unit of the dot matrix distribution of the adhesive dots is a regular hexagon, and the adhesive dots distributed in multiple regular hexagons form a honeycomb structure in the main body area or the bending area.

[0009] According to some embodiments of the present invention, the base film is further provided with an annular sealing area, the annular sealing area extends around the boundary of the base film, and the main body area and the bending area are located within the annular sealing area; The adhesive layer also includes an adhesive strip, which is disposed within the annular sealing area.

[0010] According to some embodiments of this utility model, the width of the adhesive strip ranges from 1 to 3 millimeters.

[0011] On the other hand, this utility model embodiment also provides a battery, including the separator as described above.

[0012] The present invention has at least the following beneficial effects: by dividing the separator into a bending area that needs to be bent and a main body area that does not need to be bent, the amount of adhesive applied per unit area in the bending area is selectively reduced, thereby reducing the influence of the adhesive in the bending area on the bulging of the separator during the bending process, thus reducing the bulging of the separator, preventing the separator from separating from the electrode, and effectively improving the cell performance; and by avoiding the continuous distribution of the adhesive layer in the bending area, improving the wetting effect of the electrolyte, and preventing lithium deposition on the electrode.

[0013] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0014] The above and / or additional aspects and advantages of this utility model will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of the diaphragm structure according to an embodiment of the present invention.

[0015] Figure label: 100. Base film; 110. Main body area; 120. Bending area; 130. Annular sealing area; 200, adhesive layer; 210, adhesive dot; 220, adhesive strip. Detailed Implementation

[0016] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0017] In the description of this utility model, it should be understood that the directional descriptions, such as up, down, front, back, left, right, etc., indicate the directional or positional relationship based on the directional or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0018] In the description of this utility model, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. If "first," "second," etc., are used in the description, they are only for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the sequential relationship of the indicated technical features.

[0019] In the description of this utility model, unless otherwise explicitly defined, the terms "setting", "installation", "connection", etc. should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this utility model in combination with the specific content of the technical solution.

[0020] Please refer to Figure 1 On the one hand, this utility model embodiment provides a diaphragm, including a base film 100 and an adhesive layer 200. The base film 100 is provided with a connected main body region 110 and a bending region 120. The adhesive layer 200 is disposed on at least one side surface of the base film 100. The adhesive layer 200 includes a plurality of adhesive dots 210 distributed in a dot matrix, and the unit adhesive amount of the bending region 120 is less than the unit adhesive amount of the main body region 110.

[0021] The adhesive layer 200 has a ceramic coating on the side facing away from the base membrane 100, which is a conventional structure of the diaphragm and will not be described in detail here.

[0022] It should be noted that the battery cells in the relevant technologies have different shapes, such as cylindrical cells and square cells. In particular, for square cells with several bends, stress concentration usually occurs in the bends. If the amount of adhesive applied to the separator corresponding to the bend is the same as that on the non-bend, the adhesive layer 200 on the separator corresponding to the bend can easily cause the separator to bulge excessively, which in turn causes the separator to separate from the electrode in the cell, affecting the cell performance. Moreover, the bend will bear greater stress during the charging and discharging of the battery. If the adhesive layer 200 is continuously distributed in this area, it can easily hinder the wetting of the electrolyte, leading to lithium plating on the electrode.

[0023] According to the diaphragm of this embodiment, the diaphragm is divided into a bending area 120 that needs to be bent and a main body area 110 that does not need to be bent. The amount of adhesive applied per unit in the bending area 120 is selectively reduced, thereby reducing the influence of the adhesive in the bending area 120 on the bulging of the diaphragm during the bending process. This reduces the bulging of the diaphragm, prevents the diaphragm from separating from the electrode, and effectively improves the cell performance. It also avoids the continuous distribution of the adhesive layer 200 in the bending area 120, improves the wetting effect of the electrolyte, and prevents lithium deposition on the electrode.

[0024] In this embodiment, the selection of the bending area 120 can be based on the bending position existing in the cell during the process, or it can be determined by obtaining the stress concentration area when the separator is assembled in the cell through simulation software, and the stress concentration area is used as the bending area 120, and the non-stress concentration area is used as the main area 110.

[0025] In this embodiment, the base film 100 can be made of polypropylene (PP) or polyethylene (PE) material with a thickness of 8 to 10 micrometers, which has good mechanical properties, uniform thickness and porosity distribution.

[0026] In this embodiment, the ceramic coating can be obtained by high-speed stirring and mixing ceramic powder (such as alumina, silicon dioxide), binder (such as polyvinylidene fluoride (PVDF), sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR)), and solvent (NMP or water).

[0027] In this embodiment, Figure 1 The example diaphragm has three main areas 110 and two bending areas 120. Of course, the number of main areas 110 and bending areas 120 on the diaphragm can be adjusted based on the actual structure of the cell. For example, a square cell can have four main areas 110 and four bending areas 120.

[0028] In some embodiments, combined with Figure 1 As shown, the lattice distribution shape of the adhesive dots 210 on the main body region 110 is the same as that on the bending region 120. The identical lattice distribution shape (e.g., both are square or rhomboid arrays) means that the microscopic distribution pattern of the adhesive dots 210 in the main body region 110 and the bending region 120 is consistent. This helps to form a uniform stress distribution in the bending region 120, avoiding stress concentration at specific points due to abrupt changes in the lattice shape, thereby reducing the risk of the diaphragm breaking or wrinkling during bending.

[0029] In this embodiment, the amount of adhesive applied to the main body area 110 can be controlled between 0.1 and 0.3 g / m².

[0030] In one embodiment, combined Figure 1As shown, the distribution density of adhesive dots 210 on the main body region 110 is greater than the distribution density of adhesive dots 210 on the bending region 120. When a rectangular array is used, the spacing between adhesive dots 210 in the main body region 110 is smaller than the spacing between adhesive dots 210 in the bending region 120.

[0031] In one embodiment, the amount of adhesive applied to the adhesive dots 210 on the main body region 110 is greater than the amount of adhesive applied to the adhesive dots 210 on the bending region 120. By controlling the amount of adhesive applied to each individual adhesive dot 210, the amount of adhesive applied per unit area on the bending region 120 can also be reduced.

[0032] In some embodiments, the amount of adhesive applied to a single adhesive dot 210 in the bending region 120 is 0.3 to 0.5 times the amount applied to a single adhesive dot 210 in the main body region 110. When the ratio is below 0.3, the adhesive strength of a single adhesive dot 210 may be insufficient, posing a risk of delamination at the interface of the bending region 120 under battery assembly or long-term vibration. Conversely, when the ratio is above 0.5, the adhesive dot 210 is too rigid, excessively constraining the separator during bending, and the resulting stress may cause the separator to wrinkle or be damaged. By controlling the ratio between 0.3 and 0.5, a minimum level of reliable adhesion is ensured while maximizing the degree of freedom in bending. In some embodiments, combined with Figure 1 As shown, the smallest unit of the lattice distribution of adhesive dots 210 is a regular polygon, and the adhesive dots 210 are located at the endpoints of the regular polygon. The structure of a regular polygon (such as an array of equilateral triangles, squares, or regular hexagons) has a high degree of symmetry. This makes the constraint force and adhesive force of the adhesive layer 200 on the base film 100 uniform in all directions within the separator plane. This uniformity can effectively avoid problems such as separator wrinkles and micro-tears caused by stress concentration in a certain direction during battery manufacturing or use.

[0033] In some embodiments, combined with Figure 1 As shown, the smallest unit of the lattice distribution of adhesive dots 210 is a regular hexagon, and multiple regular hexagonal adhesive dots 210 form a honeycomb structure in the main body region 110 or the bending region 120. The honeycomb structure is known for its excellent mechanical stability, which can uniformly distribute the stresses (such as tensile force, bending stress, and electrode expansion stress) on the diaphragm from all directions to the entire adhesive layer 200, minimizing local stress concentration and effectively preventing local overstretching, micro-tears, or wrinkles of the diaphragm.

[0034] In some embodiments, combined with Figure 1 As shown, the base film 100 is also provided with an annular sealing area 130, which extends around the boundary of the base film 100, and the main body area 110 and the bending area 120 are located within the annular sealing area 130; the adhesive layer 200 also includes an adhesive strip 220, which is located within the annular sealing area 130.

[0035] In this embodiment, a continuous rubber strip 220 is provided in the annular sealing area 130 of the diaphragm, which can effectively prevent electrolyte leakage from the edge of the diaphragm and improve the overall sealing performance and structural stability of the battery cell.

[0036] In some embodiments, the width of the adhesive strip 220 ranges from 1 to 3 millimeters to ensure a certain sealing strength. In other embodiments, the width of the adhesive strip 220 can be adjusted adaptively based on the structural size of the battery cell.

[0037] On the other hand, this utility model embodiment also provides a battery, including the separator as described in the above embodiment.

[0038] The embodiments of the present utility model have been described in detail above with reference to the accompanying drawings. However, the present utility model is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present utility model.

Claims

1. A diaphragm, characterized in that, include: The base film (100) has a connected main body area (110) and a bending area (120). An adhesive layer (200) is disposed on at least one side surface of the base film (100), the adhesive layer (200) includes a plurality of adhesive dots (210) distributed in a dot matrix, and the unit amount of adhesive applied in the bending region (120) is less than the unit amount of adhesive applied in the main body region (110).

2. The diaphragm according to claim 1, characterized in that, The dot matrix distribution shape of the adhesive dots (210) on the main body area (110) is the same as the dot matrix distribution shape of the adhesive dots (210) on the bending area (120); The distribution density of the adhesive dots (210) on the main body area (110) is greater than the distribution density of the adhesive dots (210) on the bending area (120). And / or, The amount of adhesive applied to the adhesive dots (210) on the main body area (110) is greater than the amount of adhesive applied to the adhesive dots (210) on the bending area (120).

3. The diaphragm according to claim 2, characterized in that, The amount of adhesive applied to a single adhesive dot (210) in the bending area (120) is 0.3 to 0.5 times the amount of adhesive applied to a single adhesive dot (210) in the main body area (110).

4. The diaphragm according to claim 1, characterized in that, The smallest unit of the dot matrix distribution of the adhesive dots (210) is a regular polygon, and the adhesive dots (210) are located at the endpoints of the regular polygon.

5. The diaphragm according to claim 4, characterized in that, The smallest unit of the dot matrix distribution of the adhesive dots (210) is a regular hexagon, and the multiple regular hexagonal adhesive dots (210) form a honeycomb structure in the main body area (110) or the bending area (120).

6. The diaphragm according to any one of claims 1 to 5, characterized in that, The base film (100) is further provided with an annular sealing area (130), the annular sealing area (130) extends around the boundary of the base film (100), and the main body area (110) and the bending area (120) are located within the annular sealing area (130); The adhesive layer (200) also includes an adhesive strip (220), which is disposed within the annular sealing area (130).

7. The diaphragm according to claim 6, characterized in that, The width of the adhesive strip (220) ranges from 1 to 3 millimeters.

8. A battery, characterized in that, Includes the diaphragm as described in any one of claims 1 to 7.

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