Electrode sheet, battery cell, and lithium battery

Abstract

An electrode sheet, a battery cell, and a lithium battery, relating to the technical field of lithium batteries. The electrode sheet comprises a current collector and an active coating. The electrode sheet comprises an uncoated foil area, a single-sided coated area in which one side surface of the current collector is coated with the active coating, and a double-sided coated area in which two side surfaces of the current collector are coated with the active coating. A corrugated portion is provided in the uncoated foil area, the corrugated portion is connected to the single-sided coated area, and the corrugated portion is provided with serrated or arc-shaped creases. The battery cell comprises an anode sheet, a separator, and a cathode sheet, the anode sheet using the electrode sheet. The lithium battery comprises the battery cell. By means of said technical solution, the problem that a single-sided coated area of an existing lithium battery electrode sheet is prone to wrinkling after being wound is solved, the safety of battery cells is improved, and energy density loss of battery cells is avoided.

Description

Electrodes, cells and lithium batteries Technical Field

[0001] The present application relates to the technical field of lithium batteries, and in particular, to a pole piece, a battery cell and a lithium battery. Background Art

[0002] Lithium battery cells are made by winding pole pieces and separators. Pole pieces are made by coating the surface of a metal foil that serves as a current collector with an active material slurry. Depending on actual needs, the active material can be coated on one or both sides of the current collector, or a blank foil area can be left on the current collector. Generally, when winding a battery cell, the pole piece located in the innermost circle of the battery cell is rolled with blank foil. The outermost part is coated with single-sided slurry because it requires the mutual coordination of the positive and negative pole pieces and to reduce slurry waste. The outermost part of the battery cell is coated with double-sided slurry.

[0003] Oily separators are widely used in existing lithium battery cells. However, due to the inherent limitations of these separators, the thinner single-sided coated area of ​​the electrode sheet does not work well with the separator. Specifically, after the electrode sheet is wound, the single-sided coated area that cooperates with the oily separator is prone to wrinkling, and this wrinkling is particularly pronounced when the electrode sheet uses a thin current collector. Wrinkling in the single-sided coated area of ​​the electrode sheet can lead to long-term lithium deposition in the battery cell, posing a safety hazard. Therefore, in order to prevent wrinkling of the electrode sheet, the relevant process uses glue to prevent wrinkling. However, the glue takes up space within the battery cell, resulting in a loss of energy density.

[0004] Application Contents

[0005] The present application provides a pole piece, a battery cell and a lithium battery, aiming to solve the problem that the single-sided coated area of ​​the existing lithium battery pole piece is prone to wrinkling after winding, thereby improving the safety of the battery cell and avoiding the loss of battery cell energy density.

[0006] To achieve the above-mentioned purpose, the present application proposes a pole piece, including a current collector and an active coating, wherein the pole piece has a hollow foil area, a single-sided coating area coated with the active coating on one side surface of the current collector, and a double-sided coating area coated with the active coating on both sides of the current collector, and a corrugated portion is provided in the hollow foil area.

[0007] In some embodiments, the corrugated portion is connected to the single-sided coating area.

[0008] In some embodiments, the current collector is a strip of metal foil.

[0009] In some embodiments, the corrugated portion has sawtooth-shaped folds.

[0010] In some embodiments, the corrugated portion has arc-shaped folds.

[0011] The present application discloses a battery cell comprising an anode electrode piece, a cathode electrode piece, and a separator located between the anode electrode piece and the cathode electrode piece. The anode electrode piece is any of the electrode pieces described above.

[0012] In some embodiments, the battery cell is a winding structure, and the battery cell includes a straight area and a bending area; the anode electrode sheet uses the empty foil area as the starting end of the winding in the winding structure, and the anode electrode sheet forms the first bend of the bending area at the position of its empty foil area, and the corrugated portion is arranged at one end of the empty foil area close to the single-sided coated area, and the corrugated portion is located in the straight area.

[0013] In some embodiments, the distance between the end of the single-sided coating area of ​​the anode plate and the bending area is between 0.5 and 10 mm.

[0014] In some embodiments, the distance between the end of the single-sided coating area of ​​the anode plate and the bending area is 3 mm.

[0015] The present application discloses a lithium battery, comprising a housing and a battery cell as described above, wherein the battery cell is encapsulated in the housing.

[0016] The technical solution of the present application provides a corrugated portion in the bare foil area of ​​the electrode, and further arranges the corrugated portion at a position where the bare foil area connects with the single-sided coated area. After the electrode is wound, the corrugated portion can provide a buffer space for wrinkling in the single-sided coated area, thereby alleviating the wrinkling phenomenon in the single-sided coated area.

[0017] In addition, in the wound-structure battery cell, the single-sided coating area of ​​the anode electrode is located in the flat area of ​​the battery cell, so that the structure of the single-sided coating area can be maintained more intact. The probability of wrinkles in the single-sided coating area can be greatly reduced without the need for adhesive tape, thereby avoiding the problem of energy density loss.

[0018] It can be seen that the present application solves the problem that the single-sided coated area of ​​the existing lithium battery electrode is prone to wrinkling after winding, thereby improving the safety of the battery cell and avoiding the loss of energy density of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG1 is a schematic diagram of the structure of the pole piece in Example 1, wherein the corrugated portion has a serrated fold;

[0020] FIG2 is a schematic diagram of the structure of the pole piece in Example 1, wherein the corrugated portion has an arc-shaped fold;

[0021] FIG3 is a schematic diagram of the structure of the battery cell in Example 2.

[0022] Specific implementation methods of this application

[0023] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0024] In order to further understand the content, features and effects of the present application, the following embodiments are given as examples and described in detail with reference to the accompanying drawings:

[0025] Example 1

[0026] Referring to Figures 1 and 2, a pole piece 1 disclosed in the present application is shown, which includes a current collector 11 and an active coating 12, wherein the current collector 11 is a strip-shaped metal foil, and the active coating 12 is formed by coating the active material slurry on the surface of the current collector 11. The pole piece 1 includes an empty foil area 101, a single-sided coating area 102 on one side of the current collector 11 with the active coating 12, and a double-sided coating area 103 on both sides of the current collector 11 with the active coating 12, and the empty foil area 101, the single-sided coating area 102 and the double-sided coating area 103 are arranged in sequence along the length direction of the current collector 11. In the empty foil area 101, there is no active coating 12 on both sides of the current collector 11. In the single-sided coating area 102, only one side of the current collector 11 has the active coating 12. In the double-sided coating area 103, both sides of the current collector 11 have the active coating 12.

[0027] 1 and 2 , a corrugated portion 111 is provided on the current collector 11 in the empty foil area 101. The corrugated portion 111 includes a plurality of folds formed by reciprocating bending of the current collector 11. The folds may be serrated or arc-shaped. The folds make the corrugated portion 111 as a whole present a wrinkled corrugated shape. The corrugated portion 111 is connected to the single-sided coating area 102. After the electrode 1 is wound to form the battery cell 2, the corrugated portion 111 can provide a buffer space for wrinkling of the single-sided coating area 102, thereby avoiding wrinkles in the single-sided coating area 102 to a certain extent.

[0028] Example 2

[0029] 3, the present application discloses a battery cell 2, comprising an anode electrode sheet 21, a separator 23 and a cathode electrode sheet 22 stacked on each other, wherein the separator 23 is arranged between the anode electrode sheet 21 and the cathode electrode sheet 22, and the three are stacked and wound to form the above-mentioned battery cell 2, wherein the anode electrode sheet 21 adopts the electrode sheet 1 in Example 1, and the anode electrode sheet 21 is wound with the empty foil area 101 as the winding starting end in the winding structure. The battery cell 2 with the wound structure includes a straight area 201 and a bent area 202, and the anode electrode sheet 21 and the cathode electrode sheet 22 in the straight area 201 are stacked and wound. They are all straight structures, and the anode electrode piece 21 and the cathode electrode piece 22 in the bending area 202 have a certain curvature; the anode electrode piece 21 forms the first bend of the bending area 202 of the battery cell 2 at the position of its empty foil area 101, and the single-sided coated area 102 of the anode electrode piece 21 is all located in the straight area 201, and the distance D between the end of the single-sided coated area 102 of the anode electrode piece 21 and the bending area 202 is between 0.5 and 10 mm. This distance D should be greater than the length of the corrugated portion 111. In some embodiments, this distance D is 3 mm. The corrugated portion 111 of the anode electrode piece 21 is arranged on the empty foil area 101 between the end of the single-sided coated area 102 and the bending area 202, that is, the corrugated portion 111 is located on the straight area 201 and is located at one end of the empty foil area 101 close to the single-sided coated area 102.

[0030] Therefore, in the above-mentioned battery cell 2, the single-sided coated area 102 of the anode electrode 21 does not pass through the bending area 202 of the inner circle of the battery cell 2, and thus does not bend. The structure of the single-sided coated area 102 can be kept more complete, thereby greatly reducing the probability of wrinkles in the single-sided coated area 102, and the corrugated portion 111 connected to the single-sided coated area 102 can provide a buffer for the wrinkles of the single-sided coated area 102, thereby further reducing the probability of wrinkles in the single-sided coated area 102.

[0031] Example 3

[0032] The present application also discloses a lithium battery, comprising a housing and the battery cell 2 of Example 2, wherein the battery cell 2 is encapsulated in the housing.

[0033] The implementation principle and beneficial effect of the present application are that, by setting a corrugated portion 111 at the position where the empty foil area 101 of the electrode 1 is connected to the single-sided coated area 102, after the electrode 1 is wound, the corrugated portion 111 can provide a buffer space for wrinkling of the single-sided coated area 102, thereby alleviating the wrinkling phenomenon of the single-sided coated area 102. In addition, in the battery cell 2 with a wound structure, the single-sided coated area 102 of the anode electrode 21 is located in the straight area 201 of the battery cell 2, so that the structure of the single-sided coated area 102 can be maintained more intact, and the probability of wrinkling of the single-sided coated area 102 can be greatly reduced without sticking adhesive tape, thereby avoiding the problem of energy density loss.

[0034] It can be seen that the present application solves the problem that the single-sided coated area 102 of the existing lithium battery electrode 1 is prone to wrinkling after winding, thereby improving the safety of the battery cell 2 and avoiding the loss of energy density of the battery cell 2.

[0035] The above description is only a partial or preferred embodiment of the present application. Neither the text nor the drawings can limit the scope of protection of the present application. Any equivalent structural transformation made by using the contents of the present application specification and drawings under the overall concept of the present application, or direct / indirect application in other related technical fields, is included in the scope of protection of the present application.

Claims

1. A pole piece, characterized in that, It includes a current collector and an active coating. The electrode has an empty foil area, a single-sided coating area where the active coating is coated on one side surface of the current collector, and a double-sided coating area where the active coating is coated on both side surfaces of the current collector. A corrugated portion is provided in the empty foil area.

2. The pole piece according to claim 1, characterized in that, The corrugated portion is connected to the single-sided coating area.

3. The pole piece according to claim 1, characterized in that, The current collector is a strip-shaped metal foil.

4. The pole piece according to any one of claims 1-3, characterized in that, The corrugated portion has serrated creases.

5. The pole piece according to any one of claims 1-3, characterized in that, The corrugated portion has arc-shaped creases.

6. A battery cell, characterized in that, It includes an anode electrode, a cathode electrode, and a separator located between the anode electrode and the cathode electrode. The anode electrode uses the electrode according to any one of claims 1-5.

7. The battery cell according to claim 6, wherein, The battery cell has a wound structure. The battery cell includes a flat area and a bent area; In the wound structure, the anode electrode uses the empty foil area as the starting end of winding. The anode electrode forms the first bend of the bent area at the position of its empty foil area. The corrugated portion is provided at one end of the empty foil area close to the single-sided coating area, and the corrugated portion is located in the flat area.

8. The battery cell according to claim 7, characterized in that, The distance between the end of the single-sided coating area of the anode electrode and the bent area is between 0.5 and 10 mm.

9. The cell according to claim 8, wherein, The distance between the end of the single-sided coating area of the anode electrode and the bent area is 3 mm.

10. A lithium battery, characterized in that, It includes a housing and the battery cell according to any one of claims 6-9. The battery cell is encapsulated in the housing.

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