CN210926204U - Winding battery cell - Google Patents

Abstract

The utility model provides a coiling electricity core, include: the first pole piece comprises a first pole piece double-sided coating area; the second pole piece is opposite to the polarity of the first pole piece and comprises a second pole piece double-side coating area and a second pole piece single-side coating area; the second pole piece single-side coating area is arranged in a bending area when the second pole piece is wound, one side of the second pole piece single-side coating area, which is back to the winding center of the winding battery cell, is a coating area, and one side of the second pole piece single-side coating area, which faces the winding center of the winding battery cell, is an uncoated area; a diaphragm disposed between the first pole piece and the second pole piece. Compared with the prior art, the utility model discloses a first pole piece has left out the setting in single face coating district, and the department of buckling when the second pole piece is convoluteed sets up single face coating district, has improved the lithium risk of analysing that the single face district of coiling electric core exists at present, and the fracture risk does not appear in making the pole piece when improving the compaction density of pole piece, has reached the purpose that promotes electric core energy density.

Description

a wound battery

technical field

The utility model relates to the field of lithium ion batteries, in particular to a wound electric core.

Background technique

Since its commercialization, lithium-ion batteries have been widely used in various electronic products such as mobile phones, tablets, notebook computers, and mobile power supplies due to their advantages of light weight, high energy density, long cycle life, and good safety. With the development of thin and light electronic products such as mobile phones and tablets, the demand for higher energy density of batteries is increasing.

At present, the negative electrode of most manufacturers adopts dislocation continuous coating on both sides. Since the negative electrode active material (such as one or more of artificial graphite, natural graphite, amorphous carbon and hard carbon, etc.) has a lower compaction density than that of the positive electrode active material, During the rolling process, the compaction density of the single-sided coating area caused by the dislocation coating of the single and double sides of the negative electrode is much smaller than that of the negative electrode double-sided coating area. There are large differences between different regions; during the cycle of lithium-ion batteries, it is easy to cause the risk of preferential lithium precipitation in the single-sided coating area, which seriously affects the battery cycle life and safety performance.

In addition, due to the increasing demand for higher energy density of lithium-ion batteries, in order to pursue higher energy density, the compaction density of positive active materials is increasing, and at the same time, the positive current collector is getting thinner and thinner, which will make There is a risk of fragmentation after the positive electrode sheet is cold-pressed; in addition, with the continuous cycling of the battery under different conditions, the expansion of the battery due to its own material and structure causes the inner ring of the positive electrode sheet winding core to cause fragmentation risk. , causing the battery to fail.

In view of this, it is indeed necessary to provide a technical solution to solve the above problems.

Utility model content

The purpose of this utility model is to: aiming at the deficiencies of the prior art, to provide a kind of wound cell, which improves the risk of lithium precipitation on one side, improves the compaction density of the positive electrode sheet, does not cause the risk of fragmentation of the positive electrode sheet, and achieves the The purpose of improving the energy density of the cell.

In order to achieve the above object, the utility model adopts the following technical solutions:

A wound electric core, comprising:

a first pole piece, the first pole piece includes a first pole piece double-sided coating area;

The second pole piece is opposite to the polarity of the first pole piece, and the second pole piece includes a second pole piece double-sided coating area and a second pole piece single-sided coating area; the second pole piece The single-sided coating area is arranged in the bending area when the second pole piece is wound, and the side of the second pole piece single-sided coating area facing away from the winding center of the wound cell is coated. area, the side of the second pole piece single-sided coating area facing the winding center of the wound cell is an uncoated area;

A diaphragm is arranged between the first pole piece and the second pole piece.

The first pole piece of the utility model adopts continuous coating on both sides, and there is no dislocation coating. Since the first pole piece omits the single-sided coating area, the film caused by the single-sided coating area is avoided. The chip resistance and corresponding impedance increase relative to the main body, leading to the risk of lithium precipitation, which improves the cycle life and safety performance. In addition, the second pole piece of the present invention includes a single-sided coating area, the single-sided coating area is arranged in the bending area during winding, and the active material is coated on the outside of the bending area, so that the second pole piece is During the rolling process, it is ensured that the active material is not damaged or damaged, and the compaction density of the pole piece is improved without causing the risk of fragmentation caused by the bending of the wound cell, thereby significantly improving the energy density. .

Preferably, the first pole piece further includes a first empty foil area arranged at the end of the first pole piece; the second pole piece further includes a second empty foil area arranged at the end of the second pole piece , the first empty foil area is opposite to the second empty foil area.

Preferably, the first empty foil area is connected with a first tab, and the second empty foil area is connected with a second tab. If the tab is arranged inside the winding, an empty foil area needs to be reserved inside the winding, and the reserved empty foil area is often larger than the area of the tab, which will cause the gap between the tab and the coating area. There is an excess part of the empty foil area, resulting in a height difference between the empty foil area and the coating area, and the excess empty foil area is opposite to the coating area on the other pole piece, that is, the coating is formed. There is no corresponding coating area on the area, which is equivalent to a situation where there is a dislocation, which leads to a decrease in the energy density of the cell. However, in the present invention, the tabs are arranged on the empty foil area of the outer ring of the battery cell. Since this empty foil area corresponds to the empty foil area on the other pole piece, the above-mentioned situation is avoided, thereby improving the efficiency of the battery core. energy density.

Preferably, the first tab and the first empty foil area are integrally formed or the first tab is welded to the first empty foil area; the second tab and the second empty foil area The second tab is integrally formed or the second tab is welded to the second empty foil area.

Preferably, the first tab is arranged parallel to the width direction of the first pole piece; the second pole tab is arranged parallel to the width direction of the second pole piece.

Preferably, the bending area includes a bending part and two end extension areas adjacent to the bending part. Enlarging the uncoated area to extend the uncoated area to both end areas increases the force range of the second pole piece during the rolling process, and reduces the risk of fragmentation that may exist at the bend.

Preferably, the second pole piece single-side coating area includes a first single-side coating area, and the first single-side coating area is disposed in the first bending area when the second pole piece is wound.

Preferably, the second pole piece single-side coating area further includes a second single-side coating area, and the second single-side coating area is disposed in the second bending area when the second pole piece is wound.

Preferably, the second pole piece single-side coating area further includes a third single-side coating area, and the third single-side coating area is arranged in the third bending area when the second pole piece is wound. During the rolling process, the bending part of the first few windings of the battery core can reduce the stress at the bending part due to the aforementioned lack of corresponding thickness, that is, there is a great risk of fragmentation in the early stage of the winding of the battery core. , the utility model uses single-sided coating in the first three winding and bending areas, and the inner side of the bending area is set as an uncoated area, which reduces the risk of fragmentation of the active material at the inner bending place due to rolling. At the same time, the second pole piece can ensure that the active material of the second pole piece is not damaged or destroyed during the rolling process, and the compaction density of the active material can be improved without causing the risk of fragmentation caused by the bending of the wound cell. This significantly increases the energy density of the cell.

Preferably, the lengths of the uncoated regions of the first single-sided coating region, the second single-sided coating region and the third single-sided coating region are all 2-8 mm. More preferably, the lengths of the uncoated regions of the first single-sided coating region, the second single-sided coating region and the third single-sided coating region are all 3-6 mm. It is enough to keep the uncoated area within this length range. If the length of the uncoated area is too large, the range of the empty foil area will be too large, which will lead to the situation that there is no corresponding coated area in the coated area, resulting in electrical failure. On the contrary, if the length range of the uncoated area is too small, the effect of reducing the risk of fragmentation cannot be satisfied, so it is sufficient to keep the uncoated area within this range.

Preferably, at the winding center of the wound cell, the head end of the first pole piece and the head end of the second pole piece as shown form a plug-in structure. That is, the head end of the first pole piece is opposite to and partially overlapped with the head end of the second pole piece. This kind of plug-in winding can significantly save materials and improve the energy density of the cell.

Preferably, the tail end of the second pole piece further includes a section of empty foil area to form an encircling circle to surround the second pole piece.

The beneficial effects of the present utility model are:

1) The utility model provides a wound electric core, comprising: a first pole piece, the first pole piece includes a double-sided coating area of the first pole piece; a second pole piece, which is different from the first pole piece. The polarity is opposite, and the second pole piece includes the second pole piece double-sided coating area and the second pole piece single-sided coating area; the second pole piece single-sided coating area is arranged on the second pole piece The bending area during winding, the side of the second pole piece single-sided coating area facing away from the winding center of the wound battery core is the coating area, and the second pole piece single-sided coating area The side facing the winding center of the wound electric core is an uncoated area; the separator is arranged between the first pole piece and the second pole piece. Compared with the prior art, the first pole piece of the present invention omits the single-sided coating area, which avoids the situation that the membrane resistance and corresponding impedance caused by the single-sided coating area increase relative to the main body, resulting in the risk of lithium precipitation. , improve cycle life and safety performance. The second pole piece of the present invention includes a single-sided coating area, the single-sided coating area is set in the bending area during winding, and the active material is coated on the outside of the bending area, so that the second pole piece is The rolling process ensures that the active material is not damaged or damaged, and the compaction density of the pole piece is improved without causing the risk of fragmentation caused by the bending of the wound cell, thereby significantly improving the energy density. The utility model improves the risk of lithium precipitation existing in the single-sided area of the current winding cell, improves the compaction density of the pole piece without causing the risk of fragmentation of the pole piece, and achieves the purpose of improving the energy density of the cell.

2) the second pole piece single-sided coating area of the present utility model comprises that the first single-sided coating area, the second single-sided coating area and the The third single-side coating area, through the setting of the three-side single-side coating area, ensures the stability of the second pole piece and improves its compaction density.

Description of drawings

Fig. 1 is one of the structural schematic diagrams of the utility model.

Fig. 2 is the second structural schematic diagram of the utility model.

In the figure: 1-first pole piece; 11-first pole piece double-sided coating area; 12-first empty foil area; 13-first pole lug; 2-second pole piece; 21-second pole piece Single-sided coating area; 211-first single-sided coating area; 212-second single-sided coating area; 213-third single-sided coating area; 22-second pole piece double-sided coating area; 23- 2nd empty foil area; 24-second tab; 3-diaphragm.

Detailed ways

As shown in Figures 1-2, a wound cell includes:

The first pole piece 1 includes a first pole piece double-sided coating area 11 and a first empty foil area 12 arranged at the end of the first pole piece 1. The first empty foil area 12 is connected with a first pole lug 13, and the first The tab 13 is integrally formed with the first empty foil area 12 or the first tab 13 is welded to the first empty foil area 12, and the first tab 13 is arranged parallel to the width direction of the first pole piece 1; wherein, the first pole piece The double-sided coating area 11 is to coat the first active material on both sides of the first current collector, and the projection surfaces of the active material on the front and back sides are the same, that is, there is no dislocation coating area;

The second pole piece 2 is opposite to the polarity of the first pole piece 1. The second pole piece 2 includes a second pole piece double-sided coating area 22, a second pole piece single-sided coating area 21, and a second pole piece The second empty foil area 23 at the end of the sheet 2 and opposite to the first empty foil area 12; The bending point and the extension area at both ends near the bending point, the side of the second pole piece single-sided coating area 21 facing away from the winding center of the wound cell is the coating area, and the second pole piece is single-sided coating The side of the area 21 facing the winding center of the wound cell is an uncoated area; the second empty foil area 23 is connected with a second tab 24, and the second tab 24 and the second empty foil area 23 are integrally formed or formed first. The diode tabs 24 are welded to the second empty foil area 23, and the second electrode tabs 24 are arranged parallel to the width direction of the second pole piece 2; wherein, the second pole piece double-sided coating area 22 is double-coated on the second current collector. The surface is coated with the second active material; the second pole piece single-sided coating area 21 includes the first single-sided coating area 211, the second single-sided coating area 212 and the third single-sided coating area 213; the first single-sided coating area 213; The lengths of the uncoated areas of the coated area 211, the second single-sided coated area 212 and the third single-sided coated area 213 are all 2-8 mm, preferably, the lengths of the uncoated areas are all 3-6 mm;

The diaphragm 3 is arranged between the first pole piece 1 and the second pole piece 2; then the first pole piece 1, the diaphragm 3 and the second pole piece 2 are wound in the order to form a flat electric core; In addition, the head end of the first pole piece 1 and the head end of the second pole piece 2 are in a plug-in structure, so that the winding center of the wound cell forms a plug-in structure; the tail of the second pole piece 2 The end also includes an empty foil area to form an encircling circle surrounding the second pole piece 2 .

In order to make the technical solutions and advantages of the present utility model clearer, the present utility model and its beneficial effects will be described in further detail below with reference to the specific embodiments and the accompanying drawings, but the embodiments of the present utility model are not limited thereto.

Example 1

A wound electric core, comprising:

The negative electrode sheet includes a double-sided coating area of the negative electrode sheet and a first empty foil area 12 arranged at the end of the negative electrode sheet. Welded in the first empty foil area 12, the negative electrode tabs are arranged parallel to the width direction of the negative electrode sheet; wherein, the negative electrode sheet double-sided coating area is to coat the negative electrode active material on both sides on the negative electrode current collector, and the active material on both sides of the positive and negative The projection surface is the same, that is, there is no dislocation coating area, and the negative electrode current collector can use copper foil;

Positive electrode sheet, the positive electrode sheet includes a double-sided coating area of the positive electrode sheet, a single-sided coating area of the positive electrode sheet, and a second empty foil area 23 arranged at the end of the positive electrode sheet and opposite to the first empty foil area 12; The covering area is arranged in the bending area of the positive electrode sheet when it is wound, and the bending area includes the bending area and the extension areas at both ends adjacent to the bending area. One side is the coating area, and the side of the single-sided coating area of the positive electrode sheet facing the winding center of the wound cell is the uncoated area, that is, the empty foil area; the second empty foil area 23 is connected with the positive electrode ear, the positive electrode ear It is integrally formed with the second empty foil area 23 or the positive electrode lugs are welded to the second empty foil area 23, and the positive electrode lugs are arranged parallel to the width direction of the positive electrode sheet; wherein, the double-sided coating area of the positive electrode sheet is a double-sided coating on the positive electrode current collector. The positive electrode active material is coated; preferably, the single-side coating area of the positive electrode sheet includes a first single-side coating area 211, a second single-side coating area 212 and a third single-side coating area 213, and the first single-side coating area 211, the lengths of the uncoated areas of the second single-sided coating area 212 and the third single-sided coating area 213 are both 2-8 mm, preferably, the lengths of the uncoated areas are both 3-6 mm;

The separator 3 is arranged between the positive electrode sheet and the negative electrode sheet; then a flat battery cell is formed by winding the negative electrode sheet, the separator 3 and the positive electrode sheet in the order, in addition, the head end of the negative electrode sheet and the head end of the positive electrode sheet are aligned type structure, so that the winding center of the wound cell forms a plug-in structure; the tail end of the positive electrode sheet also includes a section of empty foil area to form an encircling circle to surround the positive electrode sheet.

Example 2

A wound electric core, comprising:

The positive electrode sheet includes a double-sided coating area of the positive electrode sheet and a first empty foil area 12 arranged at the end of the positive electrode sheet. It is welded to the first empty foil area 12, and the positive electrode tabs are arranged parallel to the width direction of the positive electrode sheet; wherein, the double-sided coating area of the positive electrode sheet is to coat the negative electrode active material on both sides of the positive electrode current collector, and the active material on the positive and negative sides is The projection surface is consistent, that is, there is no dislocation coating area, and the positive electrode current collector can be made of aluminum foil;

The negative electrode sheet, the negative electrode sheet includes a double-sided coating area of the negative electrode sheet, a single-sided coating area of the negative electrode sheet, and a second empty foil area 23 arranged at the end of the negative electrode sheet and opposite to the first empty foil area 12; The covering area is arranged in the bending area of the negative electrode sheet when it is wound, and the bending area includes the bending place and the extension areas at both ends adjacent to the bending place. One side is the coating area, and the side of the single-sided coating area of the negative electrode sheet facing the winding center of the wound cell is the uncoated area, that is, the empty foil area; the second empty foil area 23 is connected with the negative electrode ear, the negative electrode ear It is integrally formed with the second empty foil area 23 or the negative electrode lugs are welded to the second empty foil area 23, and the negative electrode lugs are arranged parallel to the width direction of the negative electrode sheet; wherein, the double-sided coating area of the negative electrode sheet is a double-sided coating on the negative electrode current collector. The negative electrode active material is coated; preferably, the single-side coating area of the negative electrode sheet includes a first single-side coating area 211, a second single-side coating area 212 and a third single-side coating area 213, and the first single-side coating area 213. 211, the lengths of the uncoated areas of the second single-sided coating area 212 and the third single-sided coating area 213 are both 2-8 mm, preferably, the lengths of the uncoated areas are both 3-6 mm;

The separator 3 is arranged between the positive electrode sheet and the negative electrode sheet; then a flat battery cell is formed by winding the negative electrode sheet, the separator 3 and the positive electrode sheet in the order, in addition, the head end of the negative electrode sheet and the head end of the positive electrode sheet are aligned type structure, so that the winding center of the wound cell forms a plug-in structure; the tail end of the negative electrode sheet also includes a section of empty foil area to form an encircling circle to surround the negative electrode sheet.

Based on the disclosure and teaching of the above specification, those skilled in the art to which the present invention pertains can also make changes and modifications to the above-mentioned embodiments. Therefore, the present invention is not limited to the above-mentioned specific embodiments, and any obvious improvement, replacement or modification made by those skilled in the art on the basis of the present invention belongs to the protection scope of the present invention. In addition, although some specific terms are used in this specification, these terms are only for the convenience of description and do not constitute any limitation to the present invention.

Claims (10)

1. A wound cell, comprising:

the first pole piece comprises a first pole piece double-sided coating area;

the second pole piece is opposite to the polarity of the first pole piece and comprises a second pole piece double-side coating area and a second pole piece single-side coating area; the second pole piece single-side coating area is arranged in a bending area when the second pole piece is wound, one side of the second pole piece single-side coating area, which is back to the winding center of the winding battery cell, is a coating area, and one side of the second pole piece single-side coating area, which is facing to the winding center of the winding battery cell, is an uncoated area;

a diaphragm disposed between the first pole piece and the second pole piece.

2. The wound cell of claim 1, wherein the first pole piece further comprises a first empty foil region disposed at an end of the first pole piece; the second pole piece further comprises a second empty foil area arranged at the tail end of the second pole piece, and the first empty foil area and the second empty foil area are arranged oppositely.

3. The wound cell of claim 2, wherein a first tab is connected to the first empty foil region and a second tab is connected to the second empty foil region.

4. The wound cell of claim 3, wherein the first tab is integrally formed with or welded to the first empty foil zone; the second tab and the second empty foil area are integrally formed or the second tab is welded to the second empty foil area.

5. The winding cell of claim 1, wherein the bend region comprises a bend and two end extensions adjacent to the bend.

6. The wound cell of claim 1, wherein the second pole piece single-side coated region comprises a first single-side coated region disposed at a first fold region of the second pole piece as it is wound.

7. The wound cell of claim 6, wherein the second pole piece single-side coated region further comprises a second single-side coated region disposed at a second fold region of the second pole piece as it is wound.

8. The wound cell of claim 7, wherein the second pole piece single-sided coating region further comprises a third single-sided coating region disposed at a third fold region of the second pole piece during winding.

9. The wound cell of claim 8, wherein the uncoated regions of the first, second and third single-coated regions are each 2-8 mm in length.

10. The wound cell of claim 1, wherein the first end of the first pole piece and the second pole piece form an interdigitated structure at the winding center of the wound cell.

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