Composite current collector, pole piece and power battery

Abstract

The utility model provides a composite current collector, a pole piece and a power battery. The composite current collector comprises: a base film; the two supporting structures are arranged on the two opposite sides of the base film respectively, and the supporting structures are made of conductive materials; and one side, deviating from the base film, of each supporting structure is provided with one metal layer. According to the technical scheme provided by the utility model, the supporting structure is arranged, so that the problems of chap and discontinuity of the metal layer caused by extension of the metal layer due to expansion of the silicon-based negative electrode can be avoided, thereby ensuring that the metal layer keeps stable conductivity and internal resistance of the battery cell, and avoiding the phenomena of thermal runaway and cyclic diving.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, and in particular to a composite current collector, a pole piece and a power battery. Background Art

[0002] Under the pressure of energy crisis and environmental pollution, safety, environmental protection and energy saving have become the themes of today's automobile development. New energy vehicles are highly valued and strongly supported by the transportation and energy departments due to their advantages of energy saving, environmental protection and pollution-free. Among them, power batteries, as the power source of electric vehicles, are the key components of electric vehicles. In recent years, the high price and short driving range of power batteries have always been the constraints of the development of the industry. Therefore, it is necessary to reduce costs and increase energy density. Since the current industrialization of graphite negative electrodes is close to its theoretical energy density of 372mAh / g, silicon-based negative electrodes with higher energy density are a better choice. Secondly, composite current collectors with PET and PP as base films are also the mainstream application direction due to their lighter weight and safer characteristics.

[0003] At present, the volume effect of the silicon-based negative electrode material itself will expand during the cycle, causing the composite current collector to extend. The extension process causes the metal layer on the surface of the composite current collector to crack and discontinuously, resulting in poor conductivity of the metal layer, increased internal resistance of the battery cell, thermal runaway and cycle diving. Utility Model Content

[0004] The main purpose of the utility model is to provide a composite current collector, a pole piece and a power battery, which can solve the problem in the prior art that the composite current collector expands due to the expansion of the silicon-based negative electrode material, which in turn leads to poor conductivity of the metal layer, thermal runaway and cycle diving.

[0005] In order to achieve the above-mentioned purpose, according to one aspect of the utility model, a composite current collector is provided, comprising: a base film; two support structures, respectively arranged on opposite sides of the base film, and the support structures are made of conductive materials; two metal layers, and a metal layer is provided on the side of each support structure facing away from the base film.

[0006] Furthermore, the supporting structure is a mesh structure, and a plurality of polygonal mesh holes are provided on the mesh structure.

[0007] Furthermore, the polygonal mesh is a triangular mesh.

[0008] Further, the shape of the triangular mesh is an equilateral triangle; and / or the diameter of the inscribed circle of the triangular mesh is greater than the diameter of the metal atoms of the metal layer.

[0009] Further, the support structure is made of conductive metal or conductive plastic.

[0010] Further, the support structure is made of copper or aluminum or silver.

[0011] Further, the base film is made of PE or PP.

[0012] Further, the metal layer is deposited on the corresponding support structure by evaporation or water electroplating; and / or the thickness d of the base film ranges from 6 μm to 12 μm.

[0013] According to another aspect of the present invention, a pole piece is provided, the pole piece comprising the above-mentioned composite current collector and an active material arranged on the composite current collector.

[0014] According to another aspect of the present invention, a power battery is provided. The power battery includes a positive electrode sheet and a negative electrode sheet. The positive electrode sheet and / or the negative electrode sheet is the above-mentioned electrode sheet.

[0015] By applying the technical solution of the utility model, a conductive support structure is arranged between the base film and the metal layer. When the active material attached to the surface of the metal layer (for example, the silicon-based negative electrode) expands during the cycle due to its own volume effect, the support structure can support the metal layer, thereby improving the structural stability of the metal layer, avoiding the expansion of the silicon-based negative electrode that causes the metal layer to stretch, and further causing cracks and discontinuities in the metal layer, thereby ensuring that the metal layer maintains stable conductivity and internal resistance of the battery cell, and avoiding thermal runaway and cycle diving. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

[0017] Figure 1 A schematic structural diagram of a composite current collector according to an embodiment of the utility model is shown;

[0018] Figure 2 Shows Figure 1 Schematic diagram of the assembly of a partial structure of a composite current collector (wherein the metal layer is not shown).

[0019] The above drawings include the following reference numerals:

[0020] 1. Base film; 2. Support structure; 3. Metal layer. DETAILED DESCRIPTION

[0021] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0022] See also Figure 1 and Figure 2 As shown, the utility model provides a composite current collector, including: a base film 1; two support structures 2, which are respectively arranged on opposite sides of the base film 1, and the support structures 2 are made of conductive material; two metal layers 3, and a metal layer 3 is provided on the side of each support structure 2 facing away from the base film 1.

[0023] In the above technical solution, the base film 1 is a polymer base film. Since the support structure 2 is made of a conductive material, the support structure 2 has collecting conductivity and can collect and transmit current.

[0024] Through the above-mentioned arrangement, a conductive support structure 2 is arranged between the base film 1 and the metal layer 3. When the active material (for example, the silicon-based negative electrode) attached to the surface of the metal layer 3 expands during the cycle due to its own volume effect, the support structure 2 can support the metal layer 3, thereby improving the structural stability of the metal layer 3, and avoiding the expansion of the silicon-based negative electrode that causes the metal layer 3 to stretch, thereby causing cracks and discontinuities in the metal layer, thereby ensuring that the metal layer 3 maintains stable conductivity and internal resistance of the battery cell, and avoiding thermal runaway and cycle diving.

[0025] In one embodiment of the present invention, the base film 1 and the metal layer 3 are both prior art and will not be described in detail herein.

[0026] like Figure 2 As shown, in the embodiment of the present utility model, the support structure 2 is a mesh structure, and a plurality of polygonal mesh holes are provided on the mesh structure.

[0027] Through the above arrangement, on the one hand, when the metal atoms of the metal layer 3 are attached to the support structure 2 by evaporation or water electroplating, some of the metal atoms can pass through the polygonal mesh and attach to the base film 1; on the other hand, the mesh structure with polygonal meshes can play a role similar to "reinforcement ribs". Compared with the solid structure, the mesh structure has a greater structural strength, which can avoid the problem of damage to the support structure 2 due to the expansion of the silicon-based negative electrode, thereby causing cracking of the metal layer 3.

[0028] like Figure 2 As shown, in the embodiment of the present invention, the polygonal mesh is a triangular mesh. By setting the polygonal mesh to a triangular mesh, since the triangular structure is relatively stable, the structural stability of the support structure 2 can be further improved, thereby strengthening the supporting effect of the support structure 2 on the metal layer 3 and improving the structural stability of the metal layer 3.

[0029] In another embodiment of the present invention, the polygonal mesh may also be a quadrilateral, pentagonal, hexagonal or other polygonal mesh.

[0030] like Figure 2 As shown, in the embodiment of the present invention, the shape of the triangular mesh is an equilateral triangle. By setting the shape of the triangular mesh to an equilateral triangle, the structural stability of the support structure 2 can be further enhanced, ensuring that the support structure 2 is uniformly deformed after being stressed, thereby improving the structural stability of the metal layer 3.

[0031] In the embodiment of the present invention, the diameter of the inscribed circle of the triangular mesh is larger than the diameter of the metal atoms of the metal layer 3 .

[0032] In an embodiment of the present invention, the diameter of the inscribed circle of the triangular mesh is ≥360 pm.

[0033] It should be noted that since the metal atoms of the metal layer 3 are deposited on the support structure 2 by evaporation or water electroplating, a mesh diameter on the support structure 2 that is too small will result in gaps between the metal atoms and the metal atoms will not be densely distributed, thereby affecting the performance of the metal layer 3.

[0034] Through the above setting, the inscribed circle diameter of the triangular mesh is set to be larger than the metal atom diameter of the metal layer 3, which can avoid gaps between metal atoms and ensure dense distribution of metal atoms.

[0035] In one embodiment of the present invention, the support structure 2 is made of conductive metal or conductive plastic.

[0036] In a preferred embodiment of the present invention, the support structure 2 is made of copper, aluminum or silver.

[0037] In one embodiment of the present invention, the base film 1 is made of PET or PP, wherein the PET film is a polyethylene glycol terephthalate polymer film, and the PP film is a polypropylene polymer film.

[0038] In the embodiment of the present invention, the metal layer 3 is deposited on the corresponding support structure 2 by evaporation or water electroplating. By evaporation or water electroplating, some metal atoms can be deposited on the support structure 2, and some metal atoms can be attached to the base film 1 after passing through the mesh of the support structure 2.

[0039] Both evaporation and water electroplating methods are existing technologies and will not be described in detail here.

[0040] like Figure 1As shown, in the embodiment of the utility model, the thickness d of the base film 1 ranges from 6 μm to 12 μm. This arrangement can ensure the performance of the composite current collector on the one hand, and the structural strength of the composite current collector on the other hand, thereby providing good support for the support structure 2 of the metal layer 3.

[0041] In an embodiment of the present invention, the thickness of the support structure 2 is 0.5 μm to 1 μm, and the thickness of the metal layer 3 is 0.5 μm to 1 μm.

[0042] The utility model also provides a pole piece, which comprises the above-mentioned composite current collector and an active material arranged on the composite current collector.

[0043] In the above technical solution, when the electrode is a negative electrode, the active material is a silicon-based negative electrode.

[0044] The pole piece of the utility model has all the technical features and all the technical effects of the above-mentioned composite current collector, which will not be described in detail here.

[0045] The utility model also provides a power battery, which comprises a positive electrode sheet and a negative electrode sheet, and the positive electrode sheet and / or the negative electrode sheet is the above-mentioned electrode sheet.

[0046] The power battery of the utility model has all the technical features and all the technical effects of the above-mentioned pole piece, which will not be described in detail here.

[0047] From the above description, it can be seen that the above-mentioned embodiments of the utility model achieve the following technical effects: a conductive support structure is arranged between the base film and the metal layer, and when the active material attached to the surface of the metal layer (for example, a silicon-based negative electrode) expands during the cycle due to its own volume effect, the support structure can support the metal layer, thereby improving the structural stability of the metal layer, avoiding the expansion of the silicon-based negative electrode that causes the metal layer to stretch, and further causing cracking and discontinuity of the metal layer, thereby ensuring that the metal layer maintains stable conductivity and internal resistance of the battery cell, and avoiding thermal runaway and cycle diving.

[0048] Obviously, the embodiments described above are only some embodiments of the utility model, not all embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the utility model.

[0049] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0050] The above description is only the preferred embodiment of the utility model, and is not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A composite current collector, characterized in that: include: Basement membrane (1); Two support structures (2), respectively arranged on opposite sides of the base film (1), and the support structures (2) are made of conductive material; Two metal layers (3), each of the support structures (2) is provided with the metal layer (3) on a side facing away from the base film (1).

2. The composite current collector according to claim 1, characterized in that: The support structure (2) is a mesh structure, and a plurality of polygonal mesh holes are provided on the mesh structure.

3. The composite current collector according to claim 2, characterized in that: The polygonal mesh is a triangular mesh.

4. The composite current collector according to claim 3, characterized in that: The shape of the triangular mesh is an equilateral triangle; and / or, The diameter of the inscribed circle of the triangular mesh is greater than the diameter of the metal atoms of the metal layer (3).

5. The composite current collector according to any one of claims 1 to 4, characterized in that: The supporting structure (2) is made of conductive metal or conductive plastic.

6. The composite current collector according to claim 5, characterized in that: The support structure (2) is made of copper, aluminum or silver.

7. The composite current collector according to any one of claims 1 to 4, characterized in that: The base film (1) is made of PE or PP.

8. The composite current collector according to any one of claims 1 to 4, characterized in that: The metal layer (3) is deposited on the corresponding support structure (2) by evaporation or water electroplating; and / or, The thickness d of the base film (1) ranges from 6 μm to 12 μm.

9. A pole piece, characterized in that: The pole piece comprises the composite current collector according to any one of claims 1 to 8 and an active material disposed on the composite current collector.

10. A power battery, characterized in that: The power battery comprises a positive electrode sheet and a negative electrode sheet, and the positive electrode sheet and / or the negative electrode sheet is the electrode sheet according to claim 9.

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