Pole piece, wound cell and battery

Abstract

The utility model discloses a kind of pole piece, and winding type battery and battery are disclosed, wherein pole piece includes current collector, first active material layer and second active material layer, current collector includes first polymer layer and metal layer, one end of length direction of metal layer is equipped with first recess, first polymer layer is equipped in first recess, metal layer has oppositely arranged first surface and second surface, first active material layer is equipped in first surface, second active material layer is equipped in second surface, along the length direction of metal layer, the length of second active material layer is less than the length of first active material layer, to make second surface form blank area, current collector is wound away from the end of blank area and is formed with straight edge part and bending part, part first polymer layer is located bending part, the toughness of current collector at the corner of inner circle of winding type battery can be improved, to avoid bending part to produce fracture or light transmission and other problems, the yield of winding type battery can be improved.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to an electrode, a wound cell, and a battery. Background Technology

[0002] With the development of battery technology, users have increasingly higher requirements for the energy density of wound battery cells, resulting in thinner foil materials and higher compaction density. During the hot pressing process, problems such as light transmission and breakage can easily occur at the corners of the inner ring of the wound battery cell, affecting the yield rate. Utility Model Content

[0003] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes an electrode sheet that can improve the toughness of the current collector, thereby improving the yield of wound battery cells.

[0004] This utility model also proposes a wound battery cell having the above-mentioned electrode plates.

[0005] This utility model also proposes a battery having the above-mentioned wound cell.

[0006] The electrode sheet according to a first aspect embodiment of the present invention includes: The current collector includes a first polymer layer and a metal layer. One end of the metal layer along its length is provided with a first groove, and the first polymer layer is disposed in the first groove. Along the thickness direction of the current collector, the metal layer has a first surface and a second surface disposed opposite to each other. A first active material layer is disposed on the first surface; A second active material layer is disposed on the second surface. Along the length direction of the metal layer, the length of the second active material layer is less than the length of the first active material layer, so that a blank area is formed on the second surface. The current collector is wound around one end away from the blank area and has a straight edge and a bent portion. A portion of the first polymer layer is located in the bent portion.

[0007] The electrode sheet according to the first aspect of the present invention has at least the following beneficial effects: When winding the electrode, winding begins from the end of the current collector furthest from the blank area, so that the bent portion and straight edge are located in the inner ring of the wound cell, and the blank area is located in the outer ring of the wound cell. Since part of the first polymer layer is located on the bent portion, the first polymer layer has good toughness, which improves the toughness of the bent portion. This can improve the toughness of the current collector at the corner of the inner ring of the wound cell, so as to avoid problems such as breakage or light transmission in the bent portion, and improve the yield of the wound cell.

[0008] According to some embodiments of the present invention, along the thickness direction of the current collector, the thickness of the first polymer layer is D1, which satisfies: 4μm≤D1≤5.5μm.

[0009] According to some embodiments of the present invention, the maximum thickness D2 of the metal layer satisfies: 7μm≤D2≤10μm.

[0010] According to some embodiments of the present invention, the current collector further includes a second polymer layer. The metal layer has a second groove at one end away from the first groove. The second polymer layer is disposed in the second groove. Along the thickness direction of the current collector, the projection of the second polymer layer passes through the blank area and the second active material layer.

[0011] According to some embodiments of the present invention, along the thickness direction of the current collector, the projection of a portion of the second polymer layer overlaps with the second active material layer to form a first region, and the width of the first region along the length direction of the current collector is B, satisfying: 8μm≤B≤10μm.

[0012] According to some embodiments of the present invention, the thickness of the second polymer layer along the thickness direction of the current collector is D3, which satisfies: 4μm≤D3≤5.5μm.

[0013] According to some embodiments of the present invention, along the length direction of the current collector, a first stepped groove and a second stepped groove are formed at both ends of the first surface, and the first active material layer located at both ends of the current collector is respectively accommodated in the first stepped groove and the second stepped groove.

[0014] According to some embodiments of the present invention, the first polymer layer is PET or PP.

[0015] According to a second aspect embodiment of the present invention, a wound battery cell includes: Positive electrode sheet; Negative electrode plate; The separator, the positive electrode, the separator and the negative electrode are stacked and wound in sequence to form the wound battery cell, wherein the positive electrode and / or the negative electrode are the electrodes described in the above embodiments.

[0016] The wound battery cell according to the second aspect embodiment of the present invention has at least the following beneficial effects: When using the electrode sheet of the first aspect embodiment of this utility model, the winding begins from the end of the current collector away from the blank area, so that the bent portion and the straight edge portion are located in the inner ring of the wound battery cell, and the blank area is located in the outer ring of the wound battery cell. Since part of the first polymer layer is located on the bent portion, the first polymer layer has good toughness, which improves the toughness of the bent portion. This can improve the toughness of the current collector at the corner of the inner ring of the wound battery cell, so as to avoid problems such as breakage or light transmission in the bent portion, and improve the yield of the wound battery cell.

[0017] The battery according to a third aspect of the present invention includes the wound cell described in the above embodiments.

[0018] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein: Figure 1 This is a schematic diagram of the electrode sheet structure according to an embodiment of the present invention. The electrode sheet has been wound up. Figure 2 This is a schematic diagram of the electrode sheet in an embodiment of the present invention. The electrode sheet is not wound in the figure. Figure 3 This is a schematic diagram of multiple electrodes in an embodiment of the present invention.

[0020] Icon labels: Straight edge 101, bent part 102, blank area 103, metal layer 110, first groove 111, second groove 112, first stepped groove 113, second stepped groove 114, first polymer layer 120, second polymer layer 130, first active material layer 200, second active material layer 300. Detailed Implementation

[0021] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0022] In the description of this utility model, it should be understood that the directional descriptions, such as up, down, front, back, left, right, etc., indicate the directional or positional relationship based on the directional or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0023] In the description of this utility model, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. If "first" or "second" is used in the description, it is only for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0024] In the description of this utility model, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this utility model in conjunction with the specific content of the technical solution.

[0025] In related technologies, with the development of battery technology, users have increasingly higher requirements for the energy density of wound battery cells, resulting in thinner foil materials and higher compaction density. During the hot pressing process of wound battery cells, problems such as light transmission and breakage are prone to occur at the corners of the inner ring, affecting the yield rate of wound battery cells.

[0026] Reference Figure 1 , Figure 2 According to a first aspect embodiment of the present invention, the electrode includes a current collector, a first active material layer 200, and a second active material layer 300. The current collector includes a first polymer layer 120 and a metal layer 110. A first groove 111 is provided at one end of the metal layer 110 along its length direction. The first polymer layer 120 is disposed within the first groove 111. Along the thickness direction of the current collector, the metal layer 110 has a first surface and a second surface disposed opposite to each other. The first active material layer 200 is disposed on the first surface, and the second active material layer 300 is disposed on the second surface. In the length direction of layer 110, the length of the second active material layer 300 is less than the length of the first active material layer 200, so that a blank area 103 is formed on the second surface. The end of the current collector away from the blank area 103 is wound and formed with a straight edge portion 101 and a bent portion 102. Part of the first polymer layer 120 is located in the bent portion 102. In this way, by setting the first polymer layer 120, the toughness of the current collector at the corner of the inner ring of the wound battery cell can be improved, so as to avoid problems such as breakage or light transmission in the bent portion 102, and the yield of the wound battery cell can be improved.

[0027] For example, when winding the electrode, winding begins from the end of the current collector away from the blank area 103, so that the bent portion 102 and the straight edge portion 101 are located in the inner ring of the wound cell, and the blank area 103 is located in the outer ring of the wound cell. Since part of the first polymer layer 120 is located on the bent portion 102, the first polymer layer 120 has good toughness, which improves the toughness of the bent portion 102. This can improve the toughness of the current collector at the corner of the inner ring of the wound cell, so as to avoid problems such as breakage or light transmission in the bent portion 102, and improve the yield of the wound cell.

[0028] It should be noted that the electrode can be a positive electrode or a negative electrode. When the electrode is a positive electrode, the metal layer 110 is aluminum foil, and the first active material layer 200 may include a positive active material, a positive binder, and a positive conductive agent; the second active material layer 300 may include a positive active material, a positive binder, and a positive conductive agent. When the electrode is a negative electrode, the metal layer 110 is copper foil, and the first active material layer 200 may include a negative active material, a negative binder, and a negative conductive agent; the second active material layer 300 may include a negative active material, a negative binder, and a negative conductive agent. No restrictions are imposed here.

[0029] For example Figure 2 As shown, in some embodiments of this utility model, the thickness of the first polymer layer 120 along the thickness direction of the current collector is D1, which satisfies: 4μm≤D1≤5.5μm. On the one hand, this can reduce the overall thickness of the current collector, allowing the current collector to be coated with more mass of the first active material layer 200 or the second active material layer 300, thereby increasing the energy density of the battery. On the other hand, it ensures that the first polymer layer 120 has sufficient thickness to prevent the first polymer layer 120 from breaking, thereby improving the yield of the wound battery cell.

[0030] For example, when the thickness D1 of the first polymer layer 120 along the thickness direction of the current collector is less than 4 μm, the thickness of the first polymer layer 120 is too thin, and the first polymer layer 120 located at the bending portion 102 is prone to breakage when the electrode is wound. When the thickness D1 of the first polymer layer 120 along the thickness direction of the current collector is greater than 5.5 μm, the thickness of the first polymer layer 120 is too thick, the coating quality of the first active material layer 200 and the second active material layer 300 is reduced, and the energy density of the wound cell is reduced. By setting the thickness of the first polymer layer 120 along the thickness direction of the current collector to between 4 μm and 5.5 μm, the energy density of the battery can be increased and the yield of the wound cell can be improved.

[0031] It is understood that the thickness D1 of the first polymer layer 120 along the thickness direction of the current collector can be 4μm, 4.1μm, 4.2μm, 4.3μm, 4.4μm, 4.5μm, 4.6μm, 4.7μm, 4.8μm, 4.9μm, 5.0μm, 5.1μm, 5.2μm, 5.3μm, 5.4μm, 5.5μm, or within any two of the above values.

[0032] For example Figure 2 As shown, in some embodiments of this utility model, the maximum thickness D2 of the metal layer 110 satisfies: 7μm≤D2≤10μm. On the one hand, this can reduce the overall thickness of the current collector, allowing the current collector to be coated with more mass of the first active material layer 200 or the second active material layer 300 to increase the energy density of the battery. On the other hand, it ensures that the metal layer 110 has sufficient thickness to prevent the metal layer 110 from breaking, thereby improving the yield of the wound battery cell.

[0033] For example, when the maximum thickness D2 of the metal layer 110 is less than 7 μm, the thickness of the first polymer layer 120 is too thin, and the metal layer 110 located at the bending portion 102 is prone to breakage when the electrode is wound. When the maximum thickness D2 of the metal layer 110 is greater than 10 μm, the thickness of the metal layer 110 is too thick, the coating quality of the first active material layer 200 and the second active material layer 300 is reduced, and the energy density of the wound cell is reduced. By setting the maximum thickness D2 of the metal layer 110 between 7 μm and 10 μm, the energy density of the battery can be increased and the yield of the wound cell can be improved.

[0034] It is understandable that the maximum thickness D2 of the metal layer 110 can be 7μm, 7.1μm, 7.2μm, 7.3μm, 7.4μm, 7.5μm, 7.6μm, 7.7μm, 7.8μm, 7.9μm, 8.0μm, 8.1μm, 8.2μm, 8.3μm, 8.4μm, 8.5μm, 8.6μm, 8.7μm, 8.8μm, 8.9μm, 9.0μm, 9.1μm, 9.2μm, 9.3μm, 9.4μm, 9.5μm, 9.6μm, 9.7μm, 9.8μm, 9.9μm, 10μm, or fall within the range of any two of the above values.

[0035] In some embodiments of this utility model, the current collector further includes a second polymer layer 130. The metal layer 110 has a second groove 112 at one end away from the first groove 111. The second polymer layer 130 is disposed in the second groove 112. Along the thickness direction of the current collector, the projection of the second polymer layer 130 passes through the blank area 103 and the second active material layer 300, which can improve the toughness of the current collector at the junction of single-sided coating and double-sided coating, relieve the pressure on the electrode, and thus improve the yield of the wound battery cell.

[0036] Understandably, referring to Figure 3 , Figure 3 The black rectangular blocks in the diagram refer to the cutting positions of the current collector. During electrode manufacturing, a foil is removed, and multiple receiving grooves are rolled out on the foil. A polymer layer is embedded in each receiving groove through a hot-pressing composite process. Then, a metal material of the same material as the foil is vapor-deposited onto the surface of the foil to form a current collector. Next, multiple first active material layers 200 spaced along the length of the current collector are coated on the first surface of the current collector using a coating device, and multiple second active material layers 300 spaced along the length of the current collector are coated on the second surface of the current collector. Finally, the current collector is cut at intervals between adjacent first active material layers 200 using a cutting device to divide the polymer layer into a first polymer layer 120 and a second polymer layer 130. Simultaneously, the receiving grooves are divided into a first groove 111 and a second groove 112, thereby obtaining multiple electrodes. Further details are omitted here.

[0037] In some embodiments of this utility model, along the thickness direction of the current collector, the projection of a portion of the second polymer layer 130 overlaps with the second active material layer 300 to form a first region. The width of the first region along the length direction of the current collector is B, which satisfies: 8μm≤B≤10μm. This can improve the toughness of the current collector at the junction of single-sided coating and double-sided coating, alleviate electrode pressure, and prevent the winding cell from breaking.

[0038] For example, when the width B of the first region along the length of the current collector is less than 8 μm, the width of the first region along the length of the current collector is too narrow. When the metal layer 110 is excessively extended, the second polymer layer 130 is easily misaligned with the second active material layer 300, which cannot relieve the pressure on the electrode. The wound cell is prone to strip breakage. When the width B of the first region along the length of the current collector is greater than 10 μm, the width of the first region along the length of the current collector is too wide, which increases the material cost of the second polymer layer 130 and increases the manufacturing cost of the electrode. By setting the width B of the first region along the length of the current collector in the range of 8 μm to 10 μm, strip breakage of the wound cell can be prevented and the manufacturing cost of the electrode can be reduced.

[0039] It is understandable that the width B of the first region along the length direction of the current collector can be 8μm, 8.1μm, 8.2μm, 8.3μm, 8.4μm, 8.5μm, 8.6μm, 8.7μm, 8.8μm, 8.9μm, 9.0μm, 9.1μm, 9.2μm, 9.3μm, 9.4μm, 9.5μm, 9.6μm, 9.7μm, 9.8μm, 9.9μm, 10μm, or fall within the range of any two of the above values.

[0040] In some embodiments of this utility model, along the thickness direction of the current collector, the thickness of the second polymer layer 130 is D3, satisfying: 4μm≤D3≤5.5μm. The thickness of the second polymer layer 130 is equal to the thickness of the first polymer layer 120. On the one hand, this can reduce the overall thickness of the current collector, allowing the current collector to be coated with more mass of the first active material layer 200 or the second active material layer 300, thereby increasing the energy density of the battery. On the other hand, it ensures that the second polymer layer 130 has sufficient thickness to prevent the second polymer layer 130 from breaking, thereby improving the yield of the wound battery cell.

[0041] For example, when the thickness D3 of the second polymer layer 130 along the thickness direction of the current collector is less than 4 μm, the thickness of the second polymer layer 130 is too thin. When the metal layer 110 is excessively stretched, the second polymer layer 130 is easily misaligned with the second active material layer 300, which cannot relieve the pressure on the electrode. When the thickness D3 of the second polymer layer 130 along the thickness direction of the current collector is greater than 5.5 μm, the thickness of the second polymer layer 130 is too thick. The coating quality of the first active material layer 200 and the second active material layer 300 is reduced, and the energy density of the wound cell is reduced. By setting the thickness of the first polymer layer 120 along the thickness direction of the current collector to between 4 μm and 5.5 μm, the energy density of the battery can be increased and the yield of the wound cell can be improved.

[0042] It is understandable that the thickness D3 of the second polymer layer 130 along the thickness direction of the current collector can be 4μm, 4.1μm, 4.2μm, 4.3μm, 4.4μm, 4.5μm, 4.6μm, 4.7μm, 4.8μm, 4.9μm, 5.0μm, 5.1μm, 5.2μm, 5.3μm, 5.4μm, 5.5μm, or within any two of the above values.

[0043] In some embodiments of this utility model, along the length direction of the current collector, a first stepped groove 113 and a second stepped groove 114 are formed at both ends of the first surface, respectively. The first active material layer 200 located at both ends of the current collector is respectively housed in the first stepped groove 113 and the second stepped groove 114, which can increase the corner space of the wound cell to store more electrolyte, thereby reducing lithium plating of the wound cell.

[0044] For example, when the first active material layer 200 is coated, the two ends of the first active material layer 200 are located in the first stepped groove 113 and the second stepped groove 114, respectively, making the first active material layer 200 located at both ends of the current collector more porous, which can increase the corner space of the wound cell to store more electrolyte, thereby reducing lithium plating of the wound cell.

[0045] In some embodiments of this utility model, the first polymer layer 120 is made of PET material (polyester material). PET material has good toughness and mechanical strength, which can improve the mechanical strength and toughness of the electrode sheet, thereby avoiding the current collector from breaking or breaking, and improving the yield of the wound battery cell.

[0046] As another implementation, the first polymer layer 120 is made of PP material (polypropylene material). PP material has good toughness and mechanical strength, which can improve the mechanical strength and toughness of the electrode sheet, thereby avoiding the current collector from breaking or breaking, and improving the yield of the wound battery cell.

[0047] It should be noted that the first polymer layer 120 can also be a combination of PP and PET materials, which will not be elaborated here.

[0048] In some embodiments of this utility model, the second polymer layer 130 is made of PET material. PET material has good toughness and mechanical strength, which can improve the mechanical strength and toughness of the electrode sheet, thereby preventing the current collector from breaking or breaking, and improving the yield of the wound battery cell.

[0049] As another implementation, the second polymer layer 130 is made of PP material. PP material has good toughness and mechanical strength, which can improve the mechanical strength and toughness of the electrode, thereby avoiding the current collector from breaking or breaking, and improving the yield of the wound battery cell.

[0050] It should be noted that the second polymer layer 130 can also be a combination of PP and PET materials, which will not be elaborated here.

[0051] Reference Figure 1 , Figure 2According to a second aspect of the present invention, a wound battery cell includes a positive electrode, a negative electrode, and a separator. The positive electrode, the separator, and the negative electrode are stacked and wound in sequence to form a wound battery cell. The positive electrode and / or the negative electrode are the same electrodes as those in the first aspect of the present invention, which can improve the yield of the wound battery cell.

[0052] In the wound battery cell of the second aspect embodiment of this utility model, when winding the electrode, the winding starts from the end of the current collector away from the blank area 103, so that the bent portion 102 and the straight edge portion 101 are located in the inner ring of the wound battery cell, and the blank area 103 is located in the outer ring of the wound battery cell. Since part of the first polymer layer 120 is located on the bent portion 102, the first polymer layer 120 has good toughness, which improves the toughness of the bent portion 102. This can improve the toughness of the current collector at the corner of the inner ring of the wound battery cell, so as to avoid problems such as breakage or light transmission in the bent portion 102, and improve the yield of the wound battery cell.

[0053] Reference Figure 1 , Figure 2 The battery according to the third aspect embodiment of the present invention, including the wound cell of the second aspect embodiment of the present invention, can improve the battery's service life.

[0054] In the wound cell of the second aspect embodiment of this utility model, when winding the electrode, the winding starts from the end of the current collector away from the blank area 103, so that the bent portion 102 and the straight edge portion 101 are located in the inner ring of the wound cell, and the blank area 103 is located in the outer ring of the wound cell. Since part of the first polymer layer 120 is located on the bent portion 102, the first polymer layer 120 has good toughness, which improves the toughness of the bent portion 102. This can improve the toughness of the current collector at the corner of the inner ring of the wound cell, so as to avoid problems such as breakage or light transmission in the bent portion 102, and improve the service life of the battery.

[0055] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0056] The present invention has been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the invention.

Claims

1. A pole piece for a wound cell, characterized by, include: The current collector includes a metal layer (110) and a first polymer layer (120). One end of the metal layer (110) in the length direction is provided with a first groove (111). The first polymer layer (120) is disposed in the first groove (111). Along the thickness direction of the current collector, the metal layer (110) has a first surface and a second surface disposed opposite to each other. A first active material layer (200) is disposed on the first surface; A second active material layer (300) is disposed on the second surface. Along the length direction of the metal layer (110), the length of the second active material layer (300) is less than the length of the first active material layer (200), so that a blank area (103) is formed on the second surface. The current collector is wound around one end away from the blank area (103) and has a straight edge portion (101) and a bent portion (102). A portion of the first polymer layer (120) is located in the bent portion (102).

2. The pole piece of claim 1, wherein Along the thickness direction of the current collector, the thickness of the first polymer layer (120) is D1, which satisfies: 4μm≤D1≤5.5μm.

3. The pole piece of claim 1, wherein The maximum thickness D2 of the metal layer (110) satisfies: 7μm≤D2≤10μm.

4. The pole piece of claim 1, wherein The current collector also includes a second polymer layer (130). In the length direction of the current collector, a second groove (112) is provided at one end of the metal layer (110) away from the first groove (111). The second polymer layer (130) is disposed in the second groove (112). Along the thickness direction of the current collector, the projection of the second polymer layer (130) passes through the blank area (103) and the second active material layer (300).

5. The pole piece of claim 4, wherein Along the thickness direction of the current collector, a portion of the projection of the second polymer layer (130) overlaps with the second active material layer (300) to form a first region. The width of the first region along the length direction of the current collector is B, which satisfies: 8μm≤B≤10μm.

6. The pole piece of claim 4, wherein Along the thickness direction of the current collector, the thickness of the second polymer layer (130) is D3, which satisfies: 4μm≤D3≤5.5μm.

7. The pole piece of claim 1, wherein Along the length direction of the current collector, a first stepped groove (113) and a second stepped groove (114) are formed at both ends of the first surface, and the first active material layer (200) located at both ends of the current collector is respectively housed in the first stepped groove (113) and the second stepped groove (114).

8. The pole piece of claim 1, wherein The first polymer layer (120) is PET or PP.

9. A wound cell, characterized by, include: Positive electrode sheet; Negative electrode plate; The separator, the positive electrode, the separator and the negative electrode are sequentially stacked and wound to form the wound battery cell, wherein the positive electrode and / or the negative electrode are electrodes as described in any one of claims 1 to 8.

10. A battery, characterized by Including the wound battery cell as described in claim 9.

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