CN209963150U

CN209963150U - Pole piece capable of resisting active substance coating fracture

Info

Publication number: CN209963150U
Application number: CN201920775821.0U
Authority: CN
Inventors: 谭歌; 韩笑; 李凡群; 夏塞塞; 陈阳; 张伟; 张建勇; 万华峰; 王海伦
Original assignee: Wanxiang Group Corp; Wanxiang A123 Systems Asia Co Ltd
Current assignee: Wanxiang A123 Systems Asia Co Ltd
Priority date: 2019-05-27
Filing date: 2019-05-27
Publication date: 2020-01-17
Anticipated expiration: 2029-05-27

Abstract

The utility model relates to a lithium ion battery technical field provides a cracked pole piece of anti active material coating for overcome because the inhomogeneous cohesive force variation that leads to the active material coating of pole piece internal stress dispersion appears falling powder and fracture and make electrolyte infiltration and electrolyte keep the difficulty. The pole piece comprises a conductive foil and an active substance coating, wherein the conductive foil is provided with stress dispersion holes, the stress dispersion holes are distributed on the conductive foil at intervals in an upward and downward direction of a hole column, the hole diameter is 10-50 mu m, and the number of the holes is 5-E200 per square millimeter, the active substance coating is 15.0 +/-0.5 mg/cm per single surface²The coating amount of (2) is uniformly coated on both sides of the conductive foil. The utility model can avoid the fracture of the active material coating and improve the processing performance of the pole piece; electrolyte is prevented from being difficult to maintain, and the rate performance of the battery is improved; the cycle performance of the battery is improved.

Description

Pole piece capable of resisting active substance coating fracture

Technical Field

The utility model belongs to the technical field of lithium ion battery technique and specifically relates to a cracked pole piece of anti active material coating is related to.

Background

The pole piece is a small unit structure which is composed of active substances and conductive foil and has the function of lithium ion insertion and extraction, wherein the active substances are distributed on two sides of the conductive foil. The current collector refers to a metal foil which is connected with the pole piece and can conduct the current inside the battery. The existing lithium ion battery pole piece is composed of active substances and a compact and flat metal foil, wherein the active substances are distributed on two sides of the flat metal foil, and the contact surface of the active substances and the metal foil is flat. When the coating amount of the active substance is continuously increased on the flat metal surface, the stress value of the shrinkage from the periphery to the inside of the pole piece is continuously increased, so that the phenomenon that the adhesive force is deteriorated and even the pole piece is broken during drying is caused. In addition, the pole piece coating with high coating amount is thickened, so that the electrolyte infiltration and electrolyte retention are difficult, and the cycle performance and rate performance of the battery are reduced.

For example, a "pole piece and a battery cell" disclosed in chinese patent literature, whose publication number CN 208045625U includes: a current collector comprising a first region and a second region, the first region connecting the second region; the active material layer is arranged on the surface of the first region and is spaced from the second region; the insulating layer is arranged on the first surface of the second area; the second area comprises a first end and a second end along the width direction of the first area, and the first end and the second end exceed the length of the first area, so that the space of the battery cell adopting the pole piece can be saved, the capacity of the battery cell can be improved, the effect of guiding the safety short circuit of the battery cell can be played, and the passing rate of a battery cell collision test can be improved. However, the fracture of the coating layer of the active material of the battery cannot be avoided, and the cycle performance and rate performance of the battery cannot be improved.

SUMMERY OF THE UTILITY MODEL

The utility model relates to an overcome because the inhomogeneous cohesive force variation and the fracture problem that leads to the active material coating of pole piece internal stress dispersion provides an anti active material coating cracked pole piece.

In order to achieve the above purpose, the utility model adopts the following technical scheme:

the pole piece comprises a conductive foil and an active substance coating, wherein the active substance coating is coated on two sides of the conductive foil, and a plurality of stress dispersion holes are formed in the conductive foil. Because the surface of the conductive foil is provided with the stress dispersion holes, the internal stress of the pole piece can be uniformly dispersed when the active substance is dried. The phenomena of powder falling and fracture caused by the poor binding power of the active coating and the pole piece due to uneven stress dispersion in the pole piece can be effectively avoided.

Preferably, the circumferential edges of the stress dispersion holes extend to the outside of the conductive foil to form stress dispersion hole columns, and the stress dispersion hole columns are alternately distributed on two sides of the conductive foil at intervals. If the small holes are all in the same direction, the stress distribution is not uniform, and the situation of non-uniform stress distribution can be avoided by arranging the small holes in different hole column directions.

Preferably, the stress dispersion hole pillar has a regular quadrilateral shape in a longitudinal section in a direction perpendicular to the conductive foil. Is convenient for processing and manufacturing.

Preferably, the pore diameter of the stress dispersion pores is 10 to 50 μm. The stress dispersion holes are small holes on a microscopic layer, and the aperture of the stress dispersion holes is small, so that the shape of the hole column cannot be deformed due to rolling when the conductive foil and the active substance coating are rolled.

Preferably, the number of the stress dispersion holes opened in the conductive foil is 5 to 200 per square millimeter. The contact area between the conductive foil and the electrolyte can be increased, and the electrolyte can be absorbed by the small holes, so that the cycle performance can be improved.

Preferably, the active substance coating is 15.0 +/-0.5 mg/cm per side²The coating amount of (2) is uniformly coated on both sides of the conductive foil. The active material coating with proper thickness can avoid the reduction of the cycle performance and the rate performance of the battery caused by the difficulty in the infiltration of electrolyte and the maintenance of the electrolyte.

Preferably, the rolling design compaction density of the pole piece is 1.7g/cm³. The volume of the compressible pole piece is rolled, so that the impedance of the battery is reduced, and the multiplying power of the battery is improved.

Therefore, the utility model discloses following beneficial effect has: (1) the active substance coating is prevented from being broken, and the processing performance of the pole piece is improved; (2) electrolyte is prevented from being difficult to maintain, and the rate performance of the battery is improved; (3) the cycle performance of the battery is improved.

Drawings

Fig. 1 is a schematic structural diagram of the present invention.

Fig. 2 is a sectional view along the direction a-a of the present invention.

Fig. 3 is a cross-sectional view of the present invention along the direction B-B.

In the figure: 1. conductive foil, 2, active material coating, 31, stress dispersion holes, 32, stress dispersion hole columns.

Detailed Description

The present invention will be further described with reference to the accompanying drawings and the detailed description.

As shown in fig. 1, 2, and 3, a pole piece with an active material coating layer crack resistance comprises a conductive foil 1 and an active material coating layer 2, wherein the active material coating layer is coated on two sides of the conductive foil to provide static conductivity and collect micro-current of active material, and a plurality of stress dispersion holes 31 are formed in the conductive foil and can uniformly disperse internal stress of the pole piece.

Furthermore, the circumferential edges of the stress dispersion holes extend to the outer side of the conductive foil to form stress dispersion hole columns 32, and the stress dispersion hole columns are alternately distributed on two sides of the conductive foil at intervals. The longitudinal section of the stress dispersion hole pillar in the direction perpendicular to the conductive foil is trapezoidal, and can also be rectangular or other regular quadrangles. The aperture of the stress dispersion hole is 10-50 μm. The number of the stress dispersion holes on the conductive foil is 5-200/square millimeter.

The active substance coating is 15.0 +/-0.5 mg/cm on one side²The coating amount of (2) is uniformly coated on both sides of the conductive foil. The pole piece rolling design compaction density is 1.7g/cm³。

The method adopts metal foil with the aperture of 10-50 mu m and the opening number of 5-200 per square millimeter as conductive foil, and comprises the following active substances in percentage by weight: the slurry with the active substance content of 33.10 percent, the binder content of 3.03 percent, the conductive agent content of 0.87 percent and the solvent content of 63.00 percent is 15.0 +/-0.5 mg/cm on one side²The coating amount of the porous coating is uniformly coated on the two sides of the open pore foil, and the designed compaction density of the pole piece by rolling is 1.7g/cm³。

The above embodiments are only for illustrating the technical conception and the features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and the protection scope of the present invention cannot be limited thereby, and all equivalent changes, modifications or improvements made according to the spirit of the present invention should be covered by the protection scope of the present invention.

Claims

1. The pole piece comprises a conductive foil (1) and an active substance coating (2), wherein the active substance coating is coated on two sides of the conductive foil, and the pole piece is characterized in that a plurality of stress dispersion holes (31) are formed in the conductive foil.

2. The pole piece of claim 1, wherein the stress dispersion holes have circumferential edges extending outward from the conductive foil to form stress dispersion hole pillars (32), and the stress dispersion hole pillars are alternately disposed on both sides of the conductive foil.

3. The pole piece of claim 2, wherein the stress-dispersing hole pillars have a regular quadrilateral shape in a longitudinal cross section perpendicular to the conductive foil.

4. The pole piece of claim 1 or 2, wherein the stress dispersion pores have a diameter of 10 μm to 50 μm.

5. The pole piece of claim 1 or 2, wherein the stress dispersion holes have a number of openings of 5 to 200 per square millimeter in the conductive foil.

6. The pole piece of claim 1, wherein the active material coating is 15.0 ± 0.5mg/cm on one side²The coating amount of (2) is uniformly coated on both sides of the conductive foil.

7. The pole piece of claim 1, wherein the roll design compaction density of the pole piece is 1.7g/cm³。