Pole piece and battery cell

Abstract

The utility model discloses a pole piece which comprises a current collector and an active material layer, a double-sided coating section and a single-sided coating section are arranged on the current collector along the length direction, and the thickness of the current collector on the single-sided coating section is greater than that of the current collector on the double-sided coating section; active material layers are arranged on the two opposite sides of the current collector in the double-sided coating section; and an active material layer is arranged on one side of the current collector in the single-side coating section. The thickness of the current collector at the single-face coating section is larger than that of the current collector at the double-face coating section, the high energy density of the battery cell is maintained through the double-face coating section, the mechanical strength of the single-face coating section is high, and the single-face coating section is relatively not prone to warping during rolling machining; and the problem that the negative plate is broken at the first folding corner after charging and discharging cycles is difficult to occur, so that the safety of a battery cell using the pole plate is improved. The utility model further discloses a battery cell adopting the pole piece.

Description

Technical Field

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

[0002] In some existing battery cells, a separator is arranged between the positive pole piece and the negative pole piece, and the positive pole piece, the separator and the negative pole piece are formed into a wound battery cell by means of winding and bending. The pole piece includes a current collector and an active material layer. The current collector has a double-sided coating section and a single-sided coating section. Active material layers are arranged on both sides of the double-sided coating section, and an active material layer is arranged on one side of the single-sided coating section. In order to improve the energy density of the battery cell, there is a current trend to reduce the thickness of the current collector. However, in the case of a relatively large compaction density or coating density, the mechanical properties of the thinner current collector are insufficient, and the single-sided coating section of the current collector of the pole piece is prone to warping during roll pressing; and after the negative pole piece is wound, the first folding corner of the negative pole piece is within the single-sided coating section, and after charge and discharge cycles, the negative pole piece is prone to break at the first folding corner, resulting in safety problems for the battery cell using the pole piece. Summary of the Utility Model

[0003] The utility model aims to at least solve one of the technical problems existing in the prior art. For this purpose, the utility model provides a pole piece, which can reduce the risk of warping or breaking of the single-sided coating section and improve the safety of the battery cell.

[0004] The utility model also provides a battery cell with the above-mentioned pole piece.

[0005] The pole piece according to the first aspect embodiment of the utility model includes a current collector and an active material layer. The current collector is arranged with a double-sided coating section and a single-sided coating section along the length direction, the thickness of the current collector in the single-sided coating section is greater than the thickness of the current collector in the double-sided coating section; in the double-sided coating section, active material layers are arranged on opposite sides of the current collector; in the single-sided coating section, the active material layer is arranged on one side of the current collector.

[0006] The pole piece according to the first aspect embodiment of the utility model has at least the following beneficial effects: the thickness of the current collector in the single-sided coating section is greater than that in the double-sided coating section, maintaining a relatively high energy density of the battery cell through the double-sided coating section, and the mechanical strength of the single-sided coating section is relatively high, being relatively less prone to warping during roll pressing, and when the pole piece is a negative pole piece, the problem that the negative pole piece is not prone to break at the first folding corner after charge and discharge cycles, thereby improving the safety of the battery cell using the pole piece.

[0007] According to some embodiments of the utility model, the thickness of the single-sided coating section is the same along the length direction of the current collector.

[0008] According to some embodiments of the present utility model, the thickness of the current collector in the single-sided coating section gradually increases in a direction away from the double-sided coating section.

[0009] According to some embodiments of the present utility model, at least two thickness zones are arranged in the single-sided coating section in a direction away from the double-sided coating section, and the thickness of the thickness zone farthest from the double-sided coating section is the largest.

[0010] According to some embodiments of the present utility model, the thickness of the single-sided coating section is A, and the thickness of the double-sided coating section is B, satisfying 0 < A - B ≤ 3 μm.

[0011] According to some embodiments of the present utility model, the current collector is further provided with an empty foil section, the double-sided coating section, the single-sided coating section and the empty foil section are arranged in sequence along the length direction of the current collector, and the thickness of the empty foil section is the same as the thickness of one end of the single-sided coating section close to the empty foil section.

[0012] According to some embodiments of the present utility model, at least two thickness zones are arranged in the single-sided coating section in a direction away from the double-sided coating section, the thickness of the thickness zone farthest from the double-sided coating section is the largest, and the thickness of the thickness zone farthest from the double-sided coating section is the same as the thickness of the empty foil section.

[0013] According to some embodiments of the present utility model, the single-sided coating section includes a base thickness layer and a thickening layer, the thickness of the base thickness layer is the same as that of the double-sided coating section, one end of the base thickness layer is connected to one end of the double-sided coating section, the thickening layer is located on one side of the base thickness layer, and the active material layer is arranged on the other side of the base thickness layer.

[0014] According to some embodiments of the present utility model, the current collector is copper foil or aluminum foil.

[0015] The battery cell according to the embodiment of the second aspect of the present utility model includes the above-mentioned electrode sheet.

[0016] The battery cell according to the embodiment of the second aspect of the present utility model has at least the following beneficial effects: due to the adoption of the above-mentioned electrode sheet, the battery cell has better safety.

[0017] The additional aspects and advantages of the present utility model will be partially given in the following description, partially become obvious from the following description, or be understood through the practice of the present utility model. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and / or additional aspects and advantages of the present utility model will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, wherein:

[0019] Figure 1The front view schematic diagram of the electrode plate of the first embodiment of the present utility model;

[0020] Figure 2 The front view schematic diagram of the electrode plate of the second embodiment of the present utility model;

[0021] Figure 3 The front view schematic diagram of the electrode plate of the third embodiment of the present utility model.

[0022] Reference numerals:

[0023] Current collector 100, double-sided coating section 110, single-sided coating section 120, thickness partition 121, base thickness layer 122, thickening layer 123, empty foil section 130;

[0024] Active material layer 200. Detailed implementation manners

[0025] The embodiments of the present utility model will be described in detail below. The examples of the embodiments are shown in the drawings, wherein the same or similar reference numerals indicate the same or similar elements or elements with the same or similar functions from beginning to end. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present utility model and should not be construed as a limitation to the present utility model.

[0026] In the description of the present utility model, it should be understood that the orientation descriptions such as up and down refer to the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present utility model.

[0027] In the description of the present utility model, "a plurality of" means more than two. If there is a description of the first and the second, it is only for the purpose of distinguishing technical features and should not be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence relationship of the indicated technical features.

[0028] In the description of the present utility model, unless otherwise clearly defined, words such as "set", "installed", and "connected" should be understood in a broad sense. Those skilled in the art can reasonably determine the specific meanings of the above words in the present utility model in combination with the specific content of the technical solution.

[0029] In the existing lithium battery cells, the arrangement structures of the electrode plates are usually divided into a stacked type and a wound type. The stacked type is to alternately stack the positive electrode plates and the negative electrode plates, and a separator is provided between the positive electrode plates and the negative electrode plates. There is also an electrolyte inside the battery cell.

[0030] In some existing wound battery cells, a separator is provided between the positive electrode sheet and the negative electrode sheet, and the positive electrode sheet, the separator, and the negative electrode sheet are formed into a wound battery cell by means of winding and bending. The electrode sheet includes a current collector 100 and an active material layer 200. The current collector 100 has a double-sided coating section 110 and a single-sided coating section 120. Active material layers 200 are provided on both sides of the double-sided coating section 110, and an active material layer 200 is provided on one side of the single-sided coating section 120. In order to improve the energy density of the battery cell, a current trend is to reduce the thickness of the current collector 100. However, in the case of a relatively large compaction density or coating density, the thinner current collector 100 has insufficient mechanical properties, and the single-sided coating section 120 of the current collector 100 of the electrode sheet is prone to warping during roll pressing; and after the negative electrode sheet is wound, the first folding corner of the negative electrode sheet is within the single-sided coating section 120, and after charge and discharge cycling, the negative electrode sheet is prone to breakage at the first folding corner, resulting in safety problems for the battery cell using this electrode sheet.

[0031] Referring to Figures 1 to 3 , the electrode sheet of the embodiment of the present invention includes a current collector 100 and an active material layer 200. The current collector 100 is arranged with a double-sided coating section 110 and a single-sided coating section 120 along the length direction. The thickness of the current collector 100 in the single-sided coating section 120 is greater than the thickness of the current collector 100 in the double-sided coating section 110; in the double-sided coating section 110, active material layers 200 are provided on opposite sides of the current collector 100; in the single-sided coating section 120, an active material layer 200 is provided on one side of the current collector 100.

[0032] The thickness of the current collector 100 in the single-sided coating section 120 is greater than that in the double-sided coating section 110. By means of the double-sided coating section 110, a relatively high energy density of the battery cell is maintained, and the mechanical strength of the single-sided coating section 120 is relatively high, and it is relatively not prone to warping during roll pressing, and when the electrode sheet is a negative electrode sheet, the problem that the negative electrode sheet is not prone to breakage at the first folding corner after charge and discharge cycling is solved, thereby improving the safety of the battery cell using this electrode sheet.

[0033] In the first embodiment, the thickness of the single-sided coating section 120 is the same along the length direction of the current collector 100, and the thickness processing operation of the current collector 100 is relatively convenient. Only one thickness specification of a current collector 100 needs to be changed to form a single-sided coating section 120 and a double-sided coating section 110 with different thicknesses. The relatively thin double-sided coating section 110 can enable the battery cell to have a relatively high energy density, and the relatively large single-sided coating section 120 can increase the mechanical properties and reduce the risk of warping and breakage at the corner of the single-sided coating section 120 of the electrode sheet.

[0034] In the second embodiment, the thickness of the current collector 100 in the single-sided coating section 120 gradually increases in the direction away from the double-sided coating section 110. Specifically, when the negative electrode sheet is wound, the first folding corner is at the thicker part of the single-sided coating section 120, where the mechanical strength is higher. The single-sided coating section 120 at other positions can not only appropriately improve the mechanical strength but also appropriately reduce the influence of the thickness increase on the energy density, so that the current collector 100 has a better use effect.

[0035] In the third embodiment, at least two thickness zones 121 are arranged in the single-sided coating section 120 in the direction away from the double-sided coating section 110, and the thickness of the thickness zone 121 farthest from the double-sided coating section 110 is the largest. When the negative electrode sheet is wound, the innermost first folding corner is located in the thickest thickness zone 121, and the thickest thickness zone 121 has the highest mechanical strength, which can reduce the risk of the negative electrode sheet breaking. The thickness of the other thickness zones 121 increases relative to the double-sided coating section 110, so that the mechanical strength of the other thickness zones 121 also increases, and the influence of the thickness increase on the energy density is reduced, and the warping risk of the single-sided coating section 120 is reduced, so that the current collector 100 has a better use effect. Specifically, the single-sided coating section 120 can be provided with two, three or more thickness zones 121, and those skilled in the art can specifically configure according to actual needs.

[0036] It should be understood that in some embodiments, the thicknesses of different thickness zones 121 are different and there may be no increasing or decreasing relationship. For example, when there are three thickness zones 121, the thickness of the thickness zone 121 close to the double-sided coating section 110 is J, the thickness of the thickness zone 121 farthest from the double-sided coating section 110 is L, and the thickness of the thickness zone 121 located between the two is K, and the relationship can also be K < J < L.

[0037] It should be understood that in some embodiments, the thicknesses of different thickness zones 121 are different and there is an increasing relationship. For example, when there are three or more thickness zones 121, the thickness of the thickness zone 121 close to the double-sided coating section 110 is J, the thickness of the thickness zone 121 farthest from the double-sided coating section 110 is L, and the thickness of the thickness zone 121 located between the two is K, and the relationship can also be J < K < L.

[0038] It should be understood that in some embodiments, among different thickness zones 121, the thicknesses of some non-adjacent thickness zones 121 can be the same. For example, when there are three thickness zones 121, the thickness of the thickness zone 121 close to the double-sided coating section 110 is J, the thickness of the thickness zone 121 farthest from the double-sided coating section 110 is L, and the thickness of the thickness zone 121 located between the two is K, and the relationship can also be K < J = L.

[0039] Specifically, when the electrode sheet is a positive electrode sheet, the current collector 100 is usually made of aluminum foil. By adjusting the roll gap and pressure parameters of the rolling mill during the rolling process, different thickness variations can be produced along the length direction of the current collector 100.

[0040] Specifically, when the electrode sheet is a negative electrode sheet, the current collector 100 is usually made of copper foil. By controlling the process of electrolytically generating the raw foil and controlling the current density, electrolysis time, and concentration of the copper sulfate solution, different thickness variations can be adjusted along the length direction of the current collector 100.

[0041] In the embodiment, the thickness of the single-sided coating section 120 is A, and the thickness of the double-sided coating section 110 is B, satisfying 0 < A - B ≤ 3 μm. The thickness of the above-mentioned single-sided coating section 120 meets the mechanical strength requirements, making it not easy for the single-sided coating section 120 to warp or break, and not causing the thickness of the single-sided coating section 120 to increase too much and affect the energy density of the electrode sheet, with relatively good use effects.

[0042] Specifically, when the single-sided coating section 120 has a uniform thickness, the thickness of the single-sided coating section 120 can be 0.5, 1, 1.5, 2, 2.5, or 3 microns more than the thickness of the double-sided coating section 110, etc.; when the single-sided coating section 120 has two or more thickness zones 121, each thickness zone 121 can be 0.5, 1, 1.5, 2, 2.5, or 3 microns more than the thickness of the double-sided coating section 110, etc. separately, which is convenient for processing and improving the use effects.

[0043] Preferably, A = B + N * 0.5 microns, where N can be a natural number, which is convenient for controlling the dimensional variation of the single-sided coating section 120.

[0044] In the embodiment, the current collector 100 is further provided with an empty foil section 130. The double-sided coating section 110, the single-sided coating section 120, and the empty foil section 130 are arranged in sequence along the length direction of the current collector 100. The thickness of the empty foil section 130 is the same as the thickness of the end of the single-sided coating section 120 close to the empty foil section 130. The empty foil section 130 is used as a coating gap. When producing the electrode sheet raw material, no active material is coated at the empty foil section 130, and it can be cut at the empty foil section 130 to form a separate electrode sheet, which is convenient for adapting to the existing strip electrode sheet processing technology.

[0045] In the embodiment, the single-sided coating section 120 is arranged with at least two thickness zones 121 along the direction away from the double-sided coating section 110. The thickness of the thickness zone 121 farthest from the double-sided coating section 110 is the largest, and the thickness of the thickness zone 121 farthest from the double-sided coating section 110 is the same as the thickness of the empty foil section 130, which is convenient for cutting the electrode sheet raw material at the empty foil section 130 to form a separate electrode sheet and adapting to the existing strip electrode sheet processing technology.

[0046] Specifically, the single-sided coating section 120 can be provided with two, three or more thickness partitions 121, which can be specifically configured by those skilled in the art according to actual needs.

[0047] In an embodiment, the single-sided coating section 120 includes a base thickness layer 122 and a thickening layer 123. The thickness of the base thickness layer 122 is the same as that of the double-sided coating section 110. One end of the base thickness layer 122 is connected to one end of the double-sided coating section 110. The thickening layer 123 is located on one side of the base thickness layer 122, and the active material layer 200 is disposed on the other side of the base thickness layer 122. The above structure can make the side of the electrode sheet where the active material layer 200 is coated in the single-sided coating section 120 relatively smooth, facilitating production and use.

[0048] Specifically, when the negative electrode sheet is wound, the head of the negative electrode sheet is located in the inner winding circle, and the tail of the negative electrode sheet is located in the outer winding circle. At this time, the single-sided coating section 120 of the negative electrode sheet is located at the head of the negative electrode sheet.

[0049] Specifically, when the positive electrode sheet is wound, the head of the positive electrode sheet is located in the inner winding circle, and the tail of the positive electrode sheet is located in the outer winding circle. At this time, the single-sided coating section 120 of the positive electrode sheet is located at the tail of the positive electrode sheet.

[0050] The present invention also includes a battery cell that uses the above-mentioned electrode sheet. Due to the above structure, the use safety of the battery cell can be improved without significantly affecting the energy density of the battery cell.

[0051] Specifically, the electrode sheet and battery cell structures of the present invention can be applied in a lithium battery. It can be understood that the electrode sheet and battery cell structures of the present invention can also be applied in batteries made of other materials, which can be specifically configured by those skilled in the art according to actual needs.

[0052] In the description of this specification, the descriptions with reference to terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0053] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A pole piece, characterized in that, Comprising: A current collector (100) is arranged with a double-sided coating section (110) and a single-sided coating section (120) arranged along the length direction. The thickness of the current collector (100) in the single-sided coating section (120) is greater than the thickness of the current collector (100) in the double-sided coating section (110); in the double-sided coating section (110), active material layers (200) are arranged on both opposite sides of the current collector (100); in the single-sided coating section (120), the active material layer (200) is arranged on one side of the current collector (100); at least two thickness zones (121) are arranged along the direction away from the double-sided coating section (110) in the single-sided coating section (120), and the thickness of the thickness zone (121) farthest from the double-sided coating section (110) is the largest.

2. The pole piece according to claim 1, characterized in that: The thickness of the current collector (100) in the single-sided coating section (120) gradually increases along the direction away from the double-sided coating section (110).

3. The pole piece according to claim 1, wherein: The thickness of the single-sided coating section (120) is A, and the thickness of the double-sided coating section (110) is B, satisfying 0 < A - B ≤ 3 μm.

4. The pole piece according to claim 1, wherein: The current collector (100) is further provided with a blank foil section (130). The double-sided coating section (110), the single-sided coating section (120), and the blank foil section (130) are arranged in sequence along the length direction of the current collector (100). The thickness of the blank foil section (130) is the same as the thickness of the end of the single-sided coating section (120) close to the blank foil section (130).

5. The pole piece according to claim 4, wherein: At least two thickness zones (121) are arranged along the direction away from the double-sided coating section (110) in the single-sided coating section (120). The thickness of the thickness zone (121) farthest from the double-sided coating section (110) is the largest, and the thickness of the thickness zone (121) farthest from the double-sided coating section (110) is the same as the thickness of the blank foil section (130).

6. The pole piece according to claim 1, wherein: The single-sided coating section (120) includes a base thickness layer (122) and a thickening layer (123). The thickness of the base thickness layer (122) is the same as that of the double-sided coating section (110). One end of the base thickness layer (122) is connected to one end of the double-sided coating section (110). The thickening layer (123) is located on one side of the base thickness layer (122), and the active material layer (200) is arranged on the other side of the base thickness layer (122).

7. The pole piece according to claim 1, characterized in that: The current collector (100) is copper foil or aluminum foil.

8. A battery cell, characterized in that, Including the pole piece according to any one of claims 1 to 7.

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