CN210092219U

CN210092219U - Die cutting equipment suitable for cutting lithium ion battery pole piece

Info

Publication number: CN210092219U
Application number: CN201921289278.XU
Authority: CN
Inventors: 郭永兴; 刘龙波; 高旭光
Original assignee: Jiangxi Xing Ying Technology Co Ltd
Current assignee: Jiangxi Xing Ying Technology Co Ltd
Priority date: 2019-08-09
Filing date: 2019-08-09
Publication date: 2020-02-18
Anticipated expiration: 2029-08-09

Abstract

The utility model relates to a lithium ion battery field discloses a cross cutting equipment suitable for lithium ion battery pole piece cutting, and it includes: the die cutting table is used for placing a pole piece to be cut, the pole piece comprises a coating area and a foil area, a die cutting edge is arranged right opposite to the die cutting table, the blade edge of the die cutting edge is opposite to the die cutting table, and the distance from the blade edge of the die cutting edge to the foil area is smaller than the distance from the blade edge of the die cutting edge to the coating area. By applying the technical scheme, the die cutting effect of the pole piece is improved, and the pole lug in the foil area is prevented from being broken.

Description

Die cutting equipment suitable for cutting lithium ion battery pole piece

Technical Field

The utility model relates to a lithium ion battery field discloses a lithium ion battery pole piece die-cutting technology and cross cutting equipment.

Background

The lithium ion secondary battery has the advantages of long cycle life, high energy density, high specific capacity, no pollution and the like, and has attracted the wide interest of researchers. Under the conditions of energy crisis and global warming, lithium ion secondary batteries have become one of the research hotspots as a new clean energy source.

With the wider application range of the lithium ion battery in automobile power and higher requirements on energy density, when the pole piece and the processing technology of the lithium ion battery are designed,

(1) the weight of the active substance on the foil in unit area is increased, the thickness of the coating layer is increased, the rolling pressure and the compaction density are increased, the cold hardening effect on the foil is more prominent, and the mechanical property is obviously reduced particularly in the boundary area of the coating layer and the empty foil;

(2) under the condition that the foil meets the conductive requirement, the thickness of the foil is reduced, the area of the foil with unit weight is increased, and the using amount of the foil can be reduced;

(3) in the process aspect, after coating and rolling, a die cutting mode is adopted to form conductive tabs, and meanwhile, useless foils (copper foils or aluminum foils) which do not play a role are removed.

When a series of design and process improvement for improving energy density are carried out, the problem that notches appear at the edges of the lugs in the process of die cutting for producing and manufacturing the pole pieces is solved, the proportion (the number of the notches/the number of the lugs of a winding core) randomly occurs on the pole piece of a unit winding core is about 50%, the sizes of the notches are distributed between 15 and 500 mu m, and the size of cracking of the pole piece with the notches is increased in the welding and assembling process of the post process; will continue to deteriorate during use (verified by vibration testing) until it breaks; after the tabs are broken, the balance design of the positive and negative electrode resistances is changed, and the internal resistance, the heating and the like of the battery are influenced by the broken parts of the tabs; if all of the pole pieces break, the battery is rendered non-functional.

Disclosure of Invention

An object of the embodiment of the utility model is to provide a cross cutting equipment suitable for lithium ion battery pole piece cutting, use this technical scheme to be favorable to improving the cross cutting effect of pole piece, avoid the utmost point ear fracture in foil district.

In a first aspect, the embodiment of the utility model provides a pair of cross cutting equipment suitable for cutting of lithium ion battery pole piece, include:

a die cutting table for placing a pole piece to be cut, the pole piece comprising a coating area and a foil area,

a die cutting edge is arranged in the direction opposite to the die cutting table, the blade of the die cutting edge is opposite to the die cutting table,

the distance from the blade of the die cutting edge to the foil area is smaller than the distance from the blade of the die cutting edge to the coating area.

Optionally, the blade of the die cutting edge is a straight line inclined from the direction opposite to the foil area to the coating area, and the distance between the blade and the die cutting table is gradually increased.

Therefore, by adopting the technical scheme of the embodiment of the utility model, the foil area is cut firstly, and then the coating area is cut, so that the distribution and the variation trend of the force inside the foil can be changed in the die cutting process, the stress of the foil area is reduced, the foil is protected, and the gap of the pole piece is avoided; the embodiment of the utility model provides a technical scheme is particularly useful for the application of the high (the coating thickness is big), the dense ordinary strong pole piece of compaction (for example foil thickness is 6 um), can eliminate the breach in utmost point ear district, specially adapted copper foil negative pole piece.

Drawings

FIG. 1 is a schematic diagram of the die cutting principle of die cutting of pole pieces using the die cutting die of comparative example 1;

FIG. 2 is a schematic diagram of the die cutting principle of die cutting of pole pieces using the die cutting die of comparative example 2;

fig. 3 is a schematic diagram of a die cutting principle for die cutting the pole piece by using the die cutting notch in the embodiment of the present invention.

Reference numerals:

101: a foil material; 102: a coating layer; 201: comparative example 1 die cutting the side of the edge;

301: comparative example 2 die cutting the side of the edge; 401: this embodiment die cuts the sides of the knife edge.

Detailed Description

The invention will be described in detail with reference to the specific drawings and examples, which are illustrative of the invention and are not intended to limit the invention.

The embodiment of the utility model provides a lithium ion battery pole piece die-cutting process, it includes following step:

step 1: and placing the pole piece to be die-cut on a die-cutting table of die-cutting equipment.

The pole piece in the step is coated, dried and rolled.

Step 2: the die cutting edge cuts the pole piece into a plurality of pieces.

The die cutting equipment comprises a die cutting table, wherein a die cutting edge is arranged in the direction opposite to the die cutting table, and the blade of the die cutting edge is opposite to the die cutting table.

When the die-cutting knife edge is arranged right above the die-cutting table, the knife edge of the knife edge is positioned below the knife edge, and when the knife edge is pressed downwards (or the die-cutting table is lifted), the knife edge acts on the pole piece on the die-cutting table to cut the pole piece. In this embodiment, the time when the blade on the die-cutting edge, which is opposite to the foil region on the pole piece, reaches the foil region for cutting the foil region is earlier than the time when the blade on the die-cutting edge, which is opposite to the coating region on the pole piece, reaches the coating region for cutting the coating region.

For example, the distance from the blade of the die-cutting blade to the foil area of the pole piece is smaller than the distance from the blade of the die-cutting blade to the coating area of the pole piece, and when the blade is controlled to move relatively close to the pole piece, the die-cutting blade only needs to move perpendicular to the direction of the pole piece, that is, when die-cutting is performed, the foil area on the pole piece is cut first, and then the coating area of the pole piece is cut.

The blade points of the die cutting edge in the prior art are generally on a horizontal line, and when the die cutting edge is controlled to relatively approach and displace relative to the pole piece, the thickness of the coating area is higher than that of the foil area, so that the die cutting process in the prior art is to cut the coating area and then the foil area.

The inventor is going on the utility model discloses the research in-process has carried out mechanism analysis to the phenomenon that prior art pole piece breach appears in the foil district easily, discovers prior art cross cutting in-process, and the reason that the breach appears in the foil district of pole piece is:

1. when the pole piece is rolled, the thickness of the coating area of the pole piece is greater than that of the foil area, so that the compression degree of the coating area is greater than that of the foil area, and the foil 101 extends (trace, generally invisible) under the pressure state, namely, in the foil 101, internal acting force in a foil plane exists in each area of the foil 101, the internal elastic deformation force of the foil 101 is not uniform in the non-uniform extension degree of the foil 101 in the foil area, the extension degree of the foil 101 is greater in an area closer to the coating area than in an area farther from the coating area, and the internal elastic deformation force of the area is greater;

2. at the moment when the blade cuts the pole piece, the blade generates an acting force in the plane of the foil on the pole piece contacted with the blade, and the acting force in the plane of the foil, which acts on the foil 101 in the cutting process of the blade, is superposed with the internal deformation force of the foil 101 caused by rolling.

The cutting process adopting the prior art leads the blade to reach the coating area first, so that the foil area is cut in the coating area, the foil area is both subjected to cutting action force and the superposition of internal elastic deformation force caused by rolling so as to aggravate the deformation of the foil area in the process of cutting the coating area, and the action force between the interiors of the foil area can be changed in the cutting process. When the foil area is cut, the internal deformation acting force disappears due to separation at the cutting part, the foil 101 tends to rebound due to elastic deformation, the foil area is thinner, the internal deformation force received by the foil area close to the coating area in the cutting process is larger, and the extension degree is larger, so that the retraction of the foil area close to the coating area is relatively larger (the coating area is thicker due to the thickness of the coating layer 102 and can not be retracted basically) during cutting, and a notch is easily formed in the area close to the coating area in the foil area (due to the elastic deformation of the foil 101).

And adopt this embodiment technical scheme, when the pole piece cutting, make the foil district at first by the incision, avoided the cutting in-process, the inside deformation effect of this department has effectively avoided forming the phenomenon of breach in the foil district, has improved pole piece cross cutting effect.

In order to further prove the effect of this embodiment, the utility model discloses a following realization contrast.

Taking the lithium ion battery cathode pole piece with the copper foil thickness of 6um and the two sides coated, and the thickness of each coating layer 102 of 75um as an experimental sample, taking 20 samples, and carrying out die cutting according to the same die cutting procedure.

Comparative example 1: referring to fig. 1, the die-cutting of the pole piece is performed using the die-cutting notch 201 shown in comparative example 1, and when cutting, the pole piece is brought close to the die-cutting notch, the coating area is die-cut and separated first, and then the foil area is cut in the foil area in the order from the close to the coating area to the far from the coating area, and each sample is die-cut and divided into two pieces.

Comparative example 2: referring to fig. 2, the die-cutting of the pole piece is performed by using the die-cutting notch 301 shown in comparative example 2, and during cutting, the pole piece is made to approach the die-cutting notch, the coating area is first die-cut and separated at substantially the same time, and then the foil area is formed, wherein in the foil area, the cutting time of each area is substantially the same, and each sample is die-cut and separated into two pieces.

In this embodiment, referring to fig. 3, the die-cutting blade 401 shown in fig. 3 is used to perform die-cutting on the pole piece, and during cutting, the pole piece is moved toward the die-cutting blade, the foil area is cut first, the coating area is cut later, and each sample is die-cut into two pieces.

The die-cut pole pieces of comparative examples 1 and 2 and example 1 were observed as follows:

in the part of the pole piece of comparative example 1, a gap defect occurred in the foil region near the coating region, and the ratio of the gap defect was 50%, wherein the maximum dimension of the gap width was 200 um.

The part of the pole piece of comparative example 3 also had a notch defect at the foil area near the coating area, the ratio of the notch defect was 30%, wherein the maximum size of the notch width was 100 um.

The pole piece of the present embodiment has no gap defect. In addition, in order to further verify the effect, the inventors of the present invention performed 10 consecutive tests on this example, and no notch defect occurred.

To sum up, adopt the utility model discloses technical scheme cuts the foil district earlier, cuts the coating district again, can change the distribution and the trend of change of the force inside the foil in the cross cutting process, reduces the atress in foil district, protects foil 101, avoids the pole piece to appear the breach, the utility model discloses embodiment technical scheme is applicable to all lithium ion battery's pole piece cross cutting manufacturing process, utilizes this technical scheme can reduce the structural support piece of pole piece- -the mechanical properties influence of foil 101 in the cutting process; the embodiment of the utility model provides a technical scheme is particularly useful for the application of the high (the coating thickness is big), the dense ordinary strong pole piece of compaction (for example foil thickness is 6 um), can eliminate the breach in utmost point ear district, specially adapted copper foil negative pole piece.

The above-described embodiments do not limit the scope of the present invention. Any modification, equivalent replacement, and improvement made within the spirit and principle of the above-described embodiments should be included in the protection scope of the technical solution.

Claims

1. The utility model provides a cross cutting equipment suitable for cutting of lithium ion battery pole piece, characterized by includes:

2. The die cutting equipment suitable for cutting the lithium ion battery pole piece according to claim 1,

the blade of the die cutting edge is a straight line which is inclined from the direction right opposite to the foil area to the coating area, and the distance between the blade and the die cutting table is gradually increased.