Battery cell structure

Abstract

The utility model belongs to the technical field of battery cells, and particularly relates to a cell structure. Comprising a positive plate and a negative plate, an isolating membrane is arranged between the positive plate and the negative plate; a diaphragm thickening area is arranged at the position where the isolating membrane is in contact with the corners of the positive plate or the negative plate; the diaphragm thickening area is used for thickening the thickness of the diaphragm corresponding to the cutting positions of the positive plate and the negative plate; the condition that burrs or molten beads on the edge of the pole piece pierce the isolating membrane is reduced; the existing battery cell structure is further optimized while the existing battery cell preparation process is not changed, and the safety and the electrical performance of the battery cell are optimized and improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of battery cells, and particularly relates to a cell structure. Background Art

[0002] Lithium-ion batteries have long cycles, high energy density, and can generally work between -30°C and 60°C. They have a wide application environment and are widely used in fields such as automobiles, aircraft, energy storage, and digital products.

[0003] A lithium-ion cell mainly consists of a positive electrode, a negative electrode, a separator, an electrolyte, a housing, and a cover plate. Among them, the separator, as an important part of the battery, plays a key role in separating the positive and negative electrodes and preventing the short circuit of the cell. However, during the production process of the cell, due to slitting and die-cutting on the electrode sheet, longitudinal and transverse molten beads, burrs, etc. are likely to be generated at the edge of the electrode sheet, and the separator may be punctured, resulting in large self-discharge of the cell, rapid capacity attenuation, affecting the life of the cell, and even short circuit of the cell in severe cases. Improving the quality and performance of the separator is one of the important methods to reduce the self-discharge of the cell and improve its performance.

[0004] Therefore, a cell structure is needed to avoid this situation. Summary of the Utility Model

[0005] In view of the above problems, the utility model proposes a cell structure, including a positive electrode sheet and a negative electrode sheet; a separator is arranged between the positive electrode sheet and the negative electrode sheet; a separator thickening area is arranged at the position where the separator contacts the corners of the positive electrode sheet or the negative electrode sheet; the separator thickening area is used to thicken the thickness of the separator corresponding to the cutting position of the positive electrode sheet and the negative electrode sheet.

[0006] Further, the separator thickening area includes a winding core thickening area; the winding core thickening area is used for winding preparation.

[0007] Further, the separator thickening area includes a stacking core thickening area; the stacking core thickening area is used for stacking preparation; the stacking core thickening area includes a transverse thickening area and a longitudinal thickening area.

[0008] Further, the thickness of the winding core thickening area is 1 - 10 um, and the width is 3 - 5 um.

[0009] Further, the thickness of the transverse thickening area is 1 - 10 um, and the width is 3 - 5 um; the thickness of the longitudinal thickening area is 1 - 5 um, and the width is 3 - 5 um.

[0010] Further, the thickness of the separator thickening area gradually decreases from the outside to the inside.

[0011] Further, the thickness of the separator is 5 - 12 um.

[0012] Further, an insulating substance is coated on one surface of the separator membrane.

[0013] Further, one or both sides of the separator thickening area are coated with an insulating substance.

[0014] Further, one or both sides of the separator membrane and the separator thickening area are coated with an adhesive.

[0015] By providing a separator thickening area on the separator membrane, the present disclosure reduces the situation that the separator membrane is punctured by burrs or molten beads at the edge of the electrode tab; while not changing the existing battery cell manufacturing process, the existing battery cell structure is further optimized, and the safety and electrical performance of the battery cell are optimized and improved.

[0016] Other features and advantages of the present utility model will be described in the subsequent description, and part of them will be obvious from the description, or understood by implementing the present utility model. The objectives and other advantages of the present utility model can be achieved and obtained through the structures pointed out in the description, claims and drawings. Description of the Drawings

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0018] Figure 1 Shows a front view of a lithium-ion wound core / stacked core;

[0019] Figure 2 Shows a cross-sectional structural view of a lithium-ion battery cell in an embodiment of the present utility model;

[0020] Figure 3 Shows a structural view of the thickening area of the stacked core in an embodiment of the present utility model;

[0021] Figure 4 Shows a structural view of the thickening area of the wound core in an embodiment of the present utility model;

[0022] In the figures, 1, positive electrode tab; 2, negative electrode tab; 3, separator membrane; 4, separator thickening area; 41, thickening area of the wound core; 421, transverse thickening area; 422, longitudinal thickening area. Detailed Embodiments

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Apparently, the described embodiments are some, but not all, of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0024] An embodiment of the present utility model provides a cell structure to solve the problem in the prior art that burrs or molten beads are likely to be generated at the edges of the cut pole pieces, so that the four corners of the pole pieces are likely to pierce the separator film, affecting the electrical performance and safety performance of the cell. Refer to Figure 1 and Figure 2 , which includes a positive electrode sheet 1 and a negative electrode sheet 2; a separator film 3 is arranged between the positive electrode sheet 1 and the negative electrode sheet 2; a separator thickening area 4 is arranged at the position where the separator film 3 contacts the corners of the positive electrode sheet 1 or the negative electrode sheet 2; the separator thickening area 4 is used to thicken the thickness of the separator film 3 corresponding to the cutting position of the positive electrode sheet 1 and the negative electrode sheet 2.

[0025] In one embodiment, refer to Figure 3 , the separator thickening area 4 includes a stacking core thickening area; the stacking core thickening area is used for stacking preparation; the stacking core thickening area includes a transverse thickening area 421 and a longitudinal thickening area 422.

[0026] In one embodiment, the thickness of the transverse thickening area 421 is 1 - 10 um, and the width is 3 - 5 um; the thickness of the longitudinal thickening area 422 is 1 - 5 um, and the width is 3 - 5 um.

[0027] In one embodiment, the thickness of the separator thickening area 4 gradually decreases from the outside to the inside.

[0028] The thickness of the separator film 3 is 5 - 12 um.

[0029] An insulating substance is coated on one surface of the separator film 3.

[0030] An insulating substance is coated on one or both surfaces of the separator thickening area 4.

[0031] An adhesive is coated on one or both surfaces of the separator film 3 and the separator thickening area 4.

[0032] In specific implementation, after the pole pieces go through processes such as slitting, laser cutting, and die cutting, the positive pole piece 1, the negative pole piece 2, and the separator 3 are laminated into a single cell; during the Z-shaped folding process, both sides of the positive pole piece 1 and the negative pole piece 2 come into contact with the transverse thickened area 421 on the separator 3, and the other two sides of the positive pole piece 1 and the negative pole piece 2 come into contact with the longitudinal thickened area 422 on the separator 3; then during the lamination hot pressing, foreign matters such as burrs, molten beads, and material dropping at the cutting positions of the positive pole piece 1 and the negative pole piece 2 are blocked by the transverse thickened area 421 and the longitudinal thickened area 422, reducing the risk of piercing the separator 3; at the same time, it can also increase the liquid retention capacity of the separator 3, make up for the influence of the thinned area of the pole piece, make the laminated core flatter, reduce the delamination of the pole piece at this position, and improve the later cycle of the cell; the longitudinal thickened area 422 corresponds to the cutting position of the pole piece in the Z-lamination direction during lamination, preventing the aluminum or copper metal burrs at the cutting position of the pole piece from piercing the separator 3, increasing the self-discharge rate of the cell in the later stage or causing the cell to short-circuit;

[0033] An insulating substance is coated on one surface of the separator 3, and the insulating substance can be alumina or boehmite; on the premise of ensuring the puncture strength and low thermal shrinkage rate of the separator 3, the contact impedance of the cell can be reduced as much as possible, that is, the DCR of the cell can be reduced as much as possible; the insulating substance can be coated on both sides of the separator thickened area 4, because the area of the separator thickened area 4 is small and the contact area with the pole piece is also small, and coating ceramics on both sides is beneficial to increasing the strength, further reducing the penetration of burrs or molten beads into the separator 3, and having little influence on the interface contact impedance; one side of the separator thickened area 4 can also be coated with ceramics;

[0034] An adhesive is coated on the separator 3 and the separator thickened area, and the adhesive can be PVDF or PMMA glue, which is used to adhere the pole piece during hot pressing;

[0035] The thickness of the thickened area gradually becomes thinner from the outside to the inside, making the separator 3 fit more closely with the pole piece, so as to be more tightly adhered after hot pressing;

[0036] The present disclosure sets the separator thickened area 4 on the separator 3, reducing the situation that burrs or molten beads at the edge of the pole piece pierce the separator 3; while not changing the existing cell preparation process, the existing cell structure is further optimized, and the safety and electrical performance of the cell are optimized and improved.

[0037] In one embodiment, referring to Figure 4 , the separator thickened area 4 includes a winding core thickened area 41; the winding core thickened area 41 is used for winding preparation.

[0038] The thickness of the winding core thickened area 41 is 1-10 um, and the width is 3-5 um.

[0039] In specific implementation, when the separator 3, the positive electrode sheet 1, and the negative electrode sheet 2 are prepared by winding, the corners of the positive electrode sheet 1 and the negative electrode sheet 2 come into contact with the winding core thickening area 41 on the separator 3. While reducing the risk of the separator 3 being pierced by burrs on the positive electrode sheet 1 or the negative electrode sheet 2, it can also compensate for the influence of the thinning area in the thickness direction of the electrode sheet, making the winding core more flat, reducing the delamination of the electrode sheet at this position, and reducing the entry of foreign substances such as metal, graphite, and dust into the environment during the winding core preparation process.

[0040] Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A battery cell structure, characterized in that, It includes a positive electrode sheet (1) and a negative electrode sheet (2); a separator membrane (3) is arranged between the positive electrode sheet (1) and the negative electrode sheet (2); a separator thickening area (4) is arranged at the position where the separator membrane (3) contacts the corners of the positive electrode sheet (1) or the negative electrode sheet (2); the separator thickening area (4) is used to thicken the thickness of the separator membrane (3) corresponding to the cutting position of the positive electrode sheet (1) and the negative electrode sheet (2).

2. The cell structure according to claim 1, wherein, The separator thickening area (4) includes a winding core thickening area (41); the winding core thickening area (41) is used for winding preparation.

3. The core cell structure according to claim 1, characterized in that The separator thickening area (4) includes a stacking core thickening area; the stacking core thickening area is used for stacking preparation; the stacking core thickening area includes a transverse thickening area (421) and a longitudinal thickening area (422).

4. The cell structure according to claim 2, wherein, The thickness of the winding core thickening area (41) is 1-10 um, and the width is 3-5 um.

5. The cell structure according to claim 3, characterized in that The thickness of the transverse thickening area (421) is 1-10 um, and the width is 3-5 um; the thickness of the longitudinal thickening area (422) is 1-5 um, and the width is 3-5 um.

6. A cell structure according to claim 2 or 3, characterized in that, The thickness of the separator thickening area (4) gradually decreases from the outside to the inside.

7. The core structure according to claim 6, characterized in that, The thickness of the separator membrane (3) is 5-12 um.

8. A cell structure according to claim 7, characterized in that An insulating substance is coated on one surface of the separator membrane (3).

9. A cell structure according to claim 8, wherein An insulating substance is coated on one or both sides of the separator thickening area (4).

10. A battery cell structure according to claim 9, wherein, An adhesive is coated on one or both sides of the separator membrane (3) and the separator thickening area (4).

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