Current collector and negative electrode sheet

Abstract

The utility model relates to the technical field of lithium ion battery especially, it relates to current collector and negative pole piece. The current collector in the negative pole piece includes foil, first structural layer and second structural layer, the foil is provided with first through -hole, first structural layer is provided with second through -hole, the both ends fixed with foil of first structural layer along the thickness direction, the projection of first through -hole and second through -hole along the thickness direction coincides, first through -hole and second through -hole constitute the through -cavity for accommodating slurry, second structural layer is fixed on any one of two foils, second structural layer is fixed on the end face of corresponding foil away from first structural layer along the thickness direction, second structural layer blocks first through -hole, the foil without fixed second structural layer has first coating surface away from first structural layer along the thickness direction, the foil with fixed second structural layer has second coating surface close to second structural layer along the thickness direction, and first coating surface and second coating surface carry out coating processing in proper order.

Description

Technical Field

[0001] This utility model relates to the field of lithium-ion battery technology, and in particular to current collectors and negative electrode sheets. Background Technology

[0002] Lithium-ion batteries have attracted much attention due to their advantages such as high capacity, long cycle life, low environmental pollution, and safe and rapid charging and discharging. To further meet practical needs, the higher the gravimetric energy density of lithium-ion batteries, the better.

[0003] In related technologies, the mass of the current collector within the electrode of a lithium-ion battery has a significant impact on the battery's gravimetric energy density. Furthermore, the current collector inevitably exhibits uneven distribution during coating, leading to lithium plating on the electrode. Therefore, reducing the current collector's weight percentage within the electrode while simultaneously addressing lithium plating is a pressing issue. Utility Model Content

[0004] The purpose of this invention is to provide a current collector and a negative electrode to solve the problem of lithium deposition on the electrode caused by the positive and negative sides during the coating process, and to reduce the mass of the current collector, reduce the weight ratio of the current collector in the negative electrode, and improve the weight energy density of the lithium-ion battery.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] Current collectors include:

[0007] Foil material, wherein the foil material is provided with a first through hole extending along the thickness direction;

[0008] A first structural layer, wherein a second through-hole extends along the thickness direction, and foil is fixed to both ends of the first structural layer along the thickness direction, and the projections of the first through-hole and the second through-hole along the thickness direction coincide, the first through-hole and the second through-hole together forming a cavity for accommodating slurry; and

[0009] The second structural layer is fixed on either of the two foils and is fixed on the end face of the corresponding foil away from the first structural layer along the thickness direction. The second structural layer blocks the first through hole.

[0010] The foil without the second structural layer has a first coating surface away from the first structural layer along the thickness direction, and the foil with the second structural layer has a second coating surface close to the second structural layer along the thickness direction. The first coating surface and the second coating surface are coated sequentially.

[0011] As an optional solution, the foil is provided with a plurality of first through holes, and the first structural layer is provided with a plurality of second through holes, each of the first through holes corresponding to one of the second through holes.

[0012] As an optional solution, the radial cross-sectional shapes of the first through holes in multiple first through holes may be the same or different;

[0013] And / or, the radial dimensions of the first through holes in multiple first through holes are the same or different;

[0014] And / or, the spacing between the first through holes in a plurality of the first through holes may be the same or different.

[0015] As an optional option, the thickness of the first structural layer is 1 to 5 μm.

[0016] Alternatively, the foil material may have a thickness of 0.5–6 μm.

[0017] As an optional option, the radial dimension of the first through hole is 0.5 to 5 mm.

[0018] Alternatively, the first structural layer may be made of polypropylene.

[0019] As an alternative, the second structural layer is made of polyethylene terephthalate.

[0020] As an optional solution, the first structural layer is non-detachably connected to the foil;

[0021] The second structural layer is detachably connected to the foil.

[0022] The negative electrode sheet includes a slurry and a current collector as described above. The slurry is disposed on both ends of the current collector along the thickness direction and in the penetration cavity within the current collector. The slurry in the penetration cavity is simultaneously connected to the slurry at both ends of the current collector along the thickness direction.

[0023] The beneficial effects of this utility model are:

[0024] The current collector provided by this utility model has a first through hole extending along the thickness direction on the foil and a second through hole extending along the thickness direction on the first structural layer. When the foil is fixed to both ends of the first structural layer along the thickness direction, the projections of the first and second through holes along the thickness direction coincide. The first and second through holes together form a penetration cavity that penetrates the foil and the first structural layer along the thickness direction. The second structural layer is fixed to the end face of either foil away from the first structural layer along the thickness direction, and the second structural layer blocks the penetration cavity. When coating is required on the current collector, the slurry is first applied to the first coating surface of the foil without the second structural layer fixed away from the first structural layer along the thickness direction. The slurry coated on the foil then enters the penetration cavity through the first through hole, completing the coating of the current collector. The first layer is coated on one side, and then the second structural layer is separated from the foil. At this time, the penetration cavity is restored to conductivity. Coating is then performed on the end face of the foil with the second structural layer fixed to it, away from the first structural layer along the thickness direction. That is, coating is performed on the second coating surface of the foil with the second structural layer fixed to it, close to the second structural layer along the thickness direction. The slurry coated on the end face comes into contact with the slurry stored in the penetration cavity, allowing lithium ions in the slurry on both sides of the two foils along the thickness direction to diffuse and communicate with each other along the penetration cavity. This effectively improves the diffusion capacity of lithium ions and effectively solves the problem of lithium deposition at the interface. This will significantly improve the charge and discharge rate capability of lithium-ion batteries. Moreover, during coating, the first and second structural layers can improve the structural strength of the foil, avoiding problems such as breakage and tearing of the foil during the coating process, thus improving the protection of the foil. In addition, the presence of the first through-hole in the foil can also reduce the mass of the foil, thereby reducing the weight ratio of the current collector in the electrode and increasing the gravimetric energy density of the lithium-ion battery.

[0025] This invention also provides a negative electrode sheet. By applying the aforementioned current collector, lithium ions in the slurry on both sides of the current collector along its thickness direction can diffuse and communicate with each other, effectively improving the diffusion capacity of lithium ions and solving the problem of lithium deposition at the interface. This significantly improves the charge and discharge rate capability of the lithium-ion battery. Furthermore, during coating, the first and second structural layers can enhance the structural strength of the foil, preventing breakage and tearing during the coating process and improving the protection of the foil. In addition, the presence of the first through-hole in the foil can reduce the mass of the foil, thereby reducing the weight ratio of the current collector in the electrode sheet and increasing the gravimetric energy density of the lithium-ion battery. Attached Figure Description

[0026] Figure 1 This is a cross-sectional schematic diagram of the current collector provided in Embodiment 1 of this utility model;

[0027] Figure 2 This is a cross-sectional schematic diagram of the slurry coated on one side of the current collector according to Embodiment 1 of this utility model;

[0028] Figure 3 This is a cross-sectional schematic diagram of the slurry coated on both sides of the current collector according to Embodiment 1 of this utility model;

[0029] Figure 4 This is a top view of the foil material provided in Embodiment 1 of this utility model;

[0030] Figure 5 This is a top view of the foil material provided in Embodiment 2 of this utility model;

[0031] Figure 6 This is a top view of the foil material provided in Embodiment 3 of this utility model;

[0032] Figure 7 This is a top view of the foil material provided in Embodiment 4 of this utility model;

[0033] Figure 8 This is a top view of the foil material provided in Embodiment 5 of this utility model;

[0034] Figure 9 This is a top view of the foil material provided in Embodiment Six of this utility model;

[0035] Figure 10 This is a top view of the foil material provided in Embodiment 7 of this utility model.

[0036] In the picture:

[0037] 100. Foil material; 110. First through hole;

[0038] 200, First structural layer; 210, Second through hole;

[0039] 300. Second structural layer;

[0040] 2000, slurry. Detailed Implementation

[0041] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, not the entire structure.

[0042] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0043] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0044] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, 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. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.

[0045] Example 1

[0046] The mass of the current collector within the electrode of a lithium-ion battery has a significant impact on the battery's gravimetric energy density. Furthermore, the coating process inevitably results in uneven distribution of the current collector, leading to lithium plating on the electrode. Therefore, reducing the current collector's weight percentage within the electrode while simultaneously addressing lithium plating is a pressing issue.

[0047] Therefore, such as Figures 1-4As shown, this embodiment provides a current collector. The current collector includes a foil 100, a first structural layer 200, and a second structural layer 300. The foil 100 has a first through-hole 110 extending along its thickness direction, and the first structural layer 200 has a second through-hole 210 extending along its thickness direction. Foil 100 is fixed to both ends of the first structural layer 200 along its thickness direction, and the projections of the first through-hole 110 and the second through-hole 210 along their thickness directions coincide. The first through-hole 110 and the second through-hole 210 together form a cavity for receiving slurry 2000. The second structural layer... The second structural layer 300 is fixed on either of the two foils 100, and the second structural layer 300 is fixed on the end face of the corresponding foil 100 away from the first structural layer 200 along the thickness direction. The second structural layer 300 blocks the first through hole 110. The foil 100 without the second structural layer 300 has a first coating surface away from the first structural layer 200 along the thickness direction, and the foil 100 with the second structural layer 300 has a second coating surface close to the second structural layer 300 along the thickness direction. The first coating surface and the second coating surface are coated sequentially.

[0048] The current collector has a first through hole 110 extending along the thickness direction on the foil 100 and a second through hole 210 extending along the thickness direction on the first structural layer 200. When the foil 100 is fixed at both ends of the first structural layer 200 along the thickness direction, the projections of the first through hole 110 and the second through hole 210 along the thickness direction coincide. The first through hole 110 and the second through hole 210 together form a through cavity that penetrates the foil 100 and the first structural layer 200 along the thickness direction. A second structural layer 300 is fixed to the end face of any foil 100 away from the first structural layer 200 along the thickness direction, and the second structural layer 300 seals the through cavity. When coating processing is required on the current collector, the slurry 2000 is first coated on the first coating surface of the foil 100 without the second structural layer 300 along the thickness direction away from the first structural layer 200. The slurry 2000 coated on the foil 100 will then enter the through cavity along the first through hole 110. After completing the single-sided coating of the current collector, the second structural layer 300 is separated from the foil 100. At this time, the penetration cavity is restored to conductivity. The end face of the foil 100 with the second structural layer 300 originally fixed thereto is coated away from the first structural layer 200 along the thickness direction. That is, the second coating surface of the foil 100 with the second structural layer 300 originally fixed thereto is coated with the second coating surface of the foil 100 with the second structural layer 300 along the thickness direction. The paste 2000 coated on the end face comes into contact with the paste 2000 stored in the penetration cavity, so that the two... Lithium ions within the slurry 2000 on both sides of the foil 100 along its thickness direction can diffuse and communicate with each other along the perforated cavity, effectively improving the diffusion capacity of lithium ions and solving the problem of lithium deposition at the interface. This significantly improves the charge and discharge rate capability of the lithium-ion battery. Furthermore, during coating, the first structural layer 200 and the second structural layer 300 enhance the structural strength of the foil 100, preventing breakage and tearing during the coating process and improving its protection. In addition, the presence of the first through-hole 110 within the foil 100 reduces its mass, thereby reducing the weight ratio of the current collector within the electrode and increasing the gravimetric energy density of the lithium-ion battery.

[0049] In this embodiment, the foil 100 is a copper foil. The electrochemical stability, high conductivity, mechanical strength, and electrolyte compatibility of the copper foil are all suitable for the battery negative electrode.

[0050] As an optional solution, the thickness of the foil 100 is 0.5–6 μm to reduce the thickness of the current collector while meeting actual requirements. In this embodiment, the thickness of the foil 100 is 2 μm. In other embodiments, the thickness of the foil 100 can be arbitrarily adjusted within the range of 0.5–6 μm according to actual requirements; this embodiment does not impose specific limitations.

[0051] In an optional embodiment, the first structural layer 200 is made of polypropylene. Polypropylene (PP) has excellent acid and alkali resistance, good electrical insulation properties, and will not be corroded when used in a battery. Furthermore, polypropylene has a certain degree of ductility, allowing it to wrap around the probe during subsequent probe testing, thus improving battery protection.

[0052] Furthermore, the thickness of the first structural layer 200 is 1–5 μm. In this embodiment, the thickness of the first structural layer 200 is 2 μm. In other embodiments, the thickness of the first structural layer 200 can be arbitrarily adjusted within the range of 1–5 μm according to actual needs; this embodiment does not impose a specific limitation.

[0053] Optionally, the second structural layer 300 is made of polyethylene terephthalate (PET). PET material has excellent mechanical properties and is widely used as an insulating film in the field of insulating packaging.

[0054] Optionally, the first structural layer 200 is non-detachably connected to the foil 100, while the second structural layer 300 is detachably connected to the foil 100, so as to separate the second structural layer 300 from the foil 100 after single-sided coating is completed. Specifically, in this embodiment, the first structural layer 200 is fixed to the foil 100 by electroplating, and the surface of the second structural layer 300 is coated with an aqueous epoxy coating liquid. A nanoscale adhesive layer is formed through online coating and transverse stretching processes, and self-adhesion to the foil 100 is achieved by van der Waals forces.

[0055] To further reduce the mass of the current collector and further prevent lithium plating, the foil 100 is provided with a plurality of first through holes 110, and the first structural layer 200 is provided with a plurality of second through holes 210, with each first through hole 110 corresponding to a second through hole 210.

[0056] In addition, such as Figure 4 As shown, the radial cross-sectional shape of the multiple first through holes 110 is circular, the radial dimensions of the multiple first through holes 110 are the same, and the spacing between the multiple first through holes 110 is the same.

[0057] Optionally, the radial dimension of the first through hole 110 is 0.5 to 5 mm. In this embodiment, the radial dimension of the first through hole 110 is 1 mm. In other embodiments, the radial dimension of the first through hole 110 can be arbitrarily adjusted within the range of 0.5 to 5 mm according to actual needs; this embodiment does not impose a specific limitation.

[0058] Example 2

[0059] This embodiment provides a current collector. The specific structure of the current collector provided in this embodiment is basically the same as that in Embodiment 1. The difference between the current collector provided in this embodiment and Embodiment 1 is that the radial dimensions of the first through holes 110 within the plurality of first through holes 110 are different.

[0060] Specifically, such as Figure 5 As shown, the radial cross-sectional shape of the plurality of first through holes 110 is circular. The radial dimensions of some first through holes 110 differ from those of others, and the spacing between adjacent first through holes 110 is the same. Specifically, the radial dimension of the first through hole 110 in the central region of the foil 100 is larger than that in the edge region to prevent breakage or tearing of the foil 100 and to protect the foil 100. In this embodiment, the radial dimension of the first through hole 110 in the central region of the foil 100 is 3 mm, and the radial dimension of the first through hole 110 in the edge region is 1 mm. In other embodiments, the actual radial dimension of the first through hole 110 can be adjusted according to actual needs; this embodiment does not impose specific limitations.

[0061] Example 3

[0062] This embodiment provides a current collector. The specific structure of the current collector provided in this embodiment is basically the same as that in Embodiment 1. The difference between the current collector provided in this embodiment and Embodiment 1 is that the spacing between the first through holes 110 in the plurality of first through holes 110 is different.

[0063] Specifically, such as Figure 6 As shown, the radial cross-sectional shape of the plurality of first through holes 110 is circular, the radial dimensions of the plurality of first through holes 110 are the same, and the spacing between adjacent first through holes 110 within the plurality of first through holes 110 is different. Specifically, the spacing between the first through holes 110 in the central region of the foil 100 is smaller than the spacing between the first through holes 110 in the edge region of the foil 100, in order to prevent the edge of the foil 100 from breaking or tearing and to protect the foil 100. It should be noted that, in this embodiment, the spacing between two adjacent first through holes 110 in the central region is 4 mm, and the spacing between two adjacent first through holes 110 in the edge region is 10 mm. In other embodiments, the spacing between two adjacent first through holes 110 can also be adjusted according to actual needs, and this embodiment does not impose a specific limitation.

[0064] Example 4

[0065] This embodiment provides a current collector. The specific structure of the current collector provided in this embodiment is basically the same as that in Embodiment 1. The difference between the current collector provided in this embodiment and Embodiment 1 is that the radial dimensions of the plurality of first through holes 110 are different, and the spacing between the plurality of first through holes 110 is different.

[0066] Specifically, such as Figure 7 As shown, the radial cross-sectional shape of the plurality of first through holes 110 is circular. The radial dimensions of some first through holes 110 and some first through holes 110 within the plurality of first through holes 110 are different, and the spacing between adjacent first through holes 110 within the plurality of first through holes 110 is different.

[0067] In this embodiment, the radial dimension of the first through hole 110 located in the central region of the foil 100 is larger than the radial dimension of the first through hole 110 located in the edge region of the foil 100. The spacing between two adjacent first through holes 110 located in the central region of the foil 100 is smaller than the radial dimension of two adjacent first through holes 110 located in the edge region of the foil 100.

[0068] Example 5

[0069] This embodiment provides a current collector. The specific structure of the current collector provided in this embodiment is basically the same as that in Embodiment 1. The difference between the current collector provided in this embodiment and Embodiment 1 is that the radial cross-sectional shape of the plurality of first through holes 110 is different.

[0070] Specifically, such as Figure 8 As shown, the radial cross-sectional shape of the multiple first through holes 110 includes circles, triangles and rectangles, the maximum radial dimension of the multiple first through holes 110 is the same, and the spacing between the multiple first through holes 110 is the same.

[0071] Example 6

[0072] This embodiment provides a current collector. The specific structure of the current collector provided in this embodiment is basically the same as that in Embodiment 1. The difference between the current collector provided in this embodiment and Embodiment 1 is that the radial cross-sectional shapes of the plurality of first through holes 110 are different and the radial dimensions of the plurality of first through holes 110 are different.

[0073] Specifically, such as Figure 9 As shown, the radial cross-sectional shape of the multiple first through holes 110 includes circles, triangles and rectangles. The maximum radial dimension of the rectangular holes, triangular holes and circular holes in the multiple first through holes 110 gradually decreases, and the spacing between the multiple first through holes 110 is the same.

[0074] Example 7

[0075] This embodiment provides a current collector. The specific structure of the current collector provided in this embodiment is basically the same as that in Embodiment 1. The difference between the current collector provided in this embodiment and Embodiment 1 is that the radial cross-sectional shape of the plurality of first through holes 110 is different, the radial size of the plurality of first through holes 110 is different, and the spacing between the plurality of first through holes 110 is different.

[0076] Specifically, such as Figure 10 As shown, the radial cross-sectional shape of the first through holes 110 includes circles, triangles and rectangles. The maximum radial dimension of the rectangular holes, triangular holes and circular holes in the multiple first through holes 110 gradually decreases. The distance between two adjacent first through holes 110 in the central region of the foil 100 is smaller than the distance between two adjacent first through holes 110 in the edge region of the foil 100.

[0077] Example 8

[0078] This embodiment provides a negative electrode sheet, which includes a slurry 2000 and a current collector provided in any of the embodiments 1 to 7 above. The current collector is provided with slurry 2000 on both ends of the current collector along the thickness direction and in the penetration cavity inside the current collector. The slurry 2000 in the penetration cavity is connected to the slurry 2000 on both ends of the current collector along the thickness direction.

[0079] This negative electrode sheet, by applying the current collector provided in any of the embodiments 1 to 7 above, allows lithium ions within the slurry 2000 on both sides of the current collector along the thickness direction to diffuse and communicate with each other, effectively improving the diffusion capacity of lithium ions and effectively solving the problem of lithium deposition at the interface. This significantly improves the charge and discharge rate capability of the lithium-ion battery. Moreover, during coating, the first structural layer 200 and the second structural layer 300 can improve the structural strength of the foil 100, preventing breakage and tearing of the foil 100 during the coating process and improving the protection of the foil 100. In addition, the presence of the first through-hole 110 in the foil 100 can reduce the mass of the foil 100, thereby reducing the weight ratio of the current collector in the electrode sheet and increasing the gravimetric energy density of the lithium-ion battery.

[0080] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating the present utility model, and are not intended to limit the implementation of the present utility model. Those skilled in the art can make various obvious changes, readjustments, and substitutions without departing from the protection scope of this utility model. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.

Claims

1. A current collector, characterized by, include: A foil (100) having a first through hole (110) extending in the thickness direction; A first structural layer (200) is provided with a second through hole (210) extending along the thickness direction. The foil (100) is fixed on both ends of the first structural layer (200) along the thickness direction. The projections of the first through hole (110) and the second through hole (210) along the thickness direction coincide. The first through hole (110) and the second through hole (210) together form a through cavity for accommodating slurry (2000). as well as The second structural layer (300) is fixed on either of the two foils (100), and the second structural layer (300) is fixed on the end face of the corresponding foil (100) away from the first structural layer (200) along the thickness direction. The second structural layer (300) blocks the first through hole (110). The foil (100) without the second structural layer (300) has a first coating surface away from the first structural layer (200) along the thickness direction, and the foil (100) with the second structural layer (300) has a second coating surface close to the second structural layer (300) along the thickness direction. The first coating surface and the second coating surface are coated sequentially.

2. The current collector of claim 1, wherein The foil (100) is provided with a plurality of first through holes (110), and the first structural layer (200) is provided with a plurality of second through holes (210), each of the first through holes (110) being provided with a corresponding second through hole (210).

3. The current collector of claim 2, wherein The radial cross-sectional shapes of the first through holes (110) within the plurality of first through holes (110) are the same or different; And / or, the radial dimensions of the first through holes (110) within the plurality of first through holes (110) are the same or different; And / or, the spacing between the first through holes (110) in the plurality of first through holes (110) is the same or different.

4. The current collector according to any one of claims 1 to 3, wherein The thickness of the first structural layer (200) is 1 to 5 μm.

5. The current collector according to any one of claims 1 to 3, characterized in that, The thickness of the foil (100) is 0.5 to 6 μm.

6. The current collector according to any one of claims 1 to 3, characterized in that, The radial dimension of the first through hole (110) is 0.5 to 5 mm.

7. The current collector according to any one of claims 1 to 3, characterized in that, The first structural layer (200) is made of polypropylene.

8. The current collector according to any one of claims 1 to 3, characterized in that, The second structural layer (300) is made of polyethylene terephthalate.

9. The current collector according to any one of claims 1 to 3, characterized in that, The first structural layer (200) is non-detachably connected to the foil (100); The second structural layer (300) is detachably connected to the foil (100).

10. A negative electrode sheet, characterized in that, The device includes a slurry (2000) and a current collector as described in any one of claims 1 to 9, wherein the current collector is provided with the slurry (2000) on both ends of the current collector along the thickness direction and in the through cavity within the current collector, and the slurry (2000) in the through cavity is simultaneously connected to the slurry (2000) on both ends of the current collector along the thickness direction.

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