Composite current collector and energy storage device

Abstract

The utility model discloses a composite current collector and an energy storage device, which belong to the technical field of current collectors and comprise a composite supporting layer, and the composite supporting layer comprises a conductive net layer and a filling layer filled in pores of the conductive net layer; the conductive layer is arranged on at least one surface of the composite supporting layer; the filling layers are two or more composite filling layers, and at least one filling layer in the composite filling layers has larger elasticity modulus compared with other filling layers. According to the composite current collector, the overall mechanical performance of the current collector can be improved to a certain extent.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of current collector, especially to a composite current collector and energy storage device. BACKGROUND

[0002] In the secondary battery, the current collector is needed, which is the part of current convergence, and its material is generally aluminum foil or copper foil; in the prior art, a composite current collector is proposed for safety consideration, which includes a polymer support layer and metal layers arranged on both sides of the support layer, which can improve the safety of the subsequent battery, and compared with the metal foil current collector, the composite structure can also reduce the weight of the current collector and improve the energy density of the lithium ion battery.

[0003] However, based on the metal layers on both surfaces of the composite current collector, which are not conductive to each other, an aluminum sheet needs to be externally connected to each tab before or after winding the pole piece in the process of preparing the lithium ion battery, which increases the process difficulty.

[0004] In the prior art, a composite substrate based on conductive mesh and polymer is used as a support layer to improve the electrical conduction performance, but the setting of the polymer layer does not greatly improve the overall thermal conductivity, pressure resistance and deformation resistance.

[0005] Further improvement and optimization are needed.

[0006] Patent document:

[0007] 1.CN113451583B Utility model content

[0008] The utility model aims at at least in certain extent solves one of the technical problems in the related art. To this end, one purpose of the utility model is to provide a composite current collector, which can improve the mechanical properties of the current collector to a certain extent.

[0009] The technical scheme of the utility model is as follows:

[0010] In the first aspect, the application discloses a composite current collector, which comprises:

[0011] The composite support layer comprises a conductive mesh layer and a filling layer filled in the pores of the conductive mesh layer.

[0012] And the conductive layer is arranged on at least one surface of the composite support layer.

[0013] Among them, the filling layer is set as two or more composite filling layers, and at least one of the composite filling layers has a greater elastic modulus than the other filling layers.

[0014] Based on the above technical scheme, the multi-layer filling layer structure can ensure sufficient tensile strength, making up for the relatively poor mechanical strength of the conductive mesh layer. Meanwhile, the layer with greater modulus in the filling layer can ensure a certain elastic deformation during subsequent battery processing, and its pressure resistance is also guaranteed, thereby ensuring the stability of the overall structure during subsequent rolling.

[0015] Further, the thickness of the conductive mesh layer is 6-300μm.

[0016] Further, the conductive mesh layer is a metal mesh or a foamed metal.

[0017] Further, the mesh number of the metal mesh is 20-1000.

[0018] Further, the porosity of the foamed metal is 85%-98%.

[0019] Further, the filling layer material is a polymer material.

[0020] Based on the above technical scheme, the mechanical properties of the support layer can be improved, and processing is facilitated.

[0021] Further, the filling layer is filled with a filler.

[0022] Based on the above technical scheme, the modulus of the filling layer can be further improved, and the mechanical properties can be increased.

[0023] Further, the filler is a heat-conducting filler.

[0024] Based on the above technical scheme, the heat-conducting properties can be increased.

[0025] Further, the total thickness of the filling layer with greater elastic modulus is 0.6-0.8 times the thickness of the conductive mesh layer.

[0026] Based on the above technical scheme, the pressure deformation of the composite support layer can be controlled, and it has a certain elastic deformation capacity, which is beneficial to the heat expansion resistance of the subsequently prepared battery and improves safety.

[0027] Further, the filling layer with greater elastic modulus is arranged on the inner side of the conductive mesh layer.

[0028] Based on the above technical scheme, the large-modulus filling layer arranged on the inner side can play a clamping role of the small-modulus filling layer arranged on the relatively outer side, avoiding the problem of falling off due to fracture.

[0029] In a second aspect, the application also discloses an energy storage device prepared based on the above composite current collector. BRIEF DESCRIPTION OF DRAWINGS

[0030] The accompanying drawings are used to provide further understanding of the present application, and constitute a part of the specification, and are used to explain the present application together with embodiments of the present application, and do not constitute a limitation to the present application. In the drawings:

[0031] Figure 1 is a sectional view of a single-layer conductive mesh layer;

[0032] Figure 2 is a case where the conductive layer and the aperture are provided on both sides, and the apertures on both sides are provided substantially symmetrically.

[0033] Wherein, the horizontal direction represents the transverse direction, and the vertical direction represents the thickness direction.

[0034] In the drawings:

[0035] 1-conductive mesh layer; 21-first filling layer; 22-second filling layer; 23-third filling layer; 3-conductive layer. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments.

[0037] Examples of the described embodiments are shown in the drawings, wherein the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary, and are intended to explain the present application, and cannot be understood as a limitation to the present application.

[0038] Referring to Figure 1 , some embodiments of the present application propose a composite current collector, comprising:

[0039] The composite support layer comprises a conductive mesh layer 1 and a filling layer filled in the apertures of the conductive mesh layer 1.

[0040] And the conductive layer 3 is arranged on both surfaces of the composite support layer.

[0041] Wherein, the filling layer comprises a first filling layer 21, a second filling layer 22 and a third filling layer 23 arranged in sequence along the thickness direction, and the second filling layer 22 has a greater elastic modulus than the first filling layer 21 and the third filling layer 23.

[0042] Based on the above current collector structure, a multi-layer filling layer structure can be used to ensure sufficient tensile strength, making up for the relatively poor mechanical strength of the conductive mesh layer 1. Meanwhile, the layer with a larger modulus in the filling layer can ensure a certain elastic deformation during subsequent battery processing, and its pressure resistance is also guaranteed, thereby ensuring the stability of the overall structure during subsequent rolling. It can improve the defects of the prior art, which only uses a conductive mesh or a single polymer filling layer material in the conductive mesh, which has relatively poor mechanical properties.

[0043] In the above structure, the thickness D of the conductive mesh layer is set to 6-300 μm; the conductive mesh layer can be at least one of a metal mesh such as an aluminum mesh, a copper mesh, and a nickel mesh, and the filling layer is arranged in the pores of the metal mesh, and the pore size is 80-1000 mesh; the conductive mesh layer can also be at least one of a foamed metal such as foamed copper, foamed nickel, and foamed aluminum, and the filling layer is arranged in the connected pores of the foamed metal, and the porosity is 85%-98%.

[0044] For the filling layer 21, 23, the material can be selected from a polymer material, and the related polymer material is a known polymer material disclosed in the prior art, which will not be described again. It has a relatively small elastic modulus, for example, the modulus is 500-2000 MPa;

[0045] The second filling layer 22 has a relatively larger elastic modulus, for example, the modulus is 1500-6000 MPa. In order to have a larger modulus, a filler such as an inorganic filler can be added to the filling layer to increase the mechanical properties of the entire film, and when further adding a conventional heat-conducting filler such as graphite (for example, the addition amount is 3%-10%), the heat-conducting performance can also be increased to a certain extent.

[0046] During molding, the conductive mesh layer 1 and the polymer film group stacked according to the filling layer order can be hot-pressed and combined above the melting point temperature to fill in the conductive mesh layer and form the filling layer.

[0047] The second filling layer 22 can also be formed in the conductive mesh layer 1 in a casting manner under negative pressure after the first conductive layer 21 is filled by hot-pressing and combining, and the third filling layer 23 is further formed by hot-pressing and combining after drying and curing.

[0048] The conductive layer 3 is made of a metal material and is deposited on at least one surface of the conductive mesh layer 1 by evaporation, sputtering, and electroplating, and the thickness is set to 0.1-2 μm. The material can be selected from copper, aluminum, nickel, chromium, etc.

[0049] In some other embodiments of the present application, the number of filler layers in the conductive mesh layer 1 can be two groups, or more than three groups; as preferred, the total thickness of the filler layer with greater elastic modulus is 0.6-0.8 times the thickness of the conductive mesh layer 1, which controls the pressure deformation of the composite support layer while having a certain elastic deformation capacity, which is beneficial to the subsequent preparation of the battery's heat-resistant expansion capacity and improves safety.

[0050] For the multi-layer filler layer structure, the thickness of each filler layer can be selected as needed. The filler layer with greater elastic modulus is preferably arranged on the inner side of the conductive mesh layer 1; the filler layers of different components can be arranged in a concentrated manner or in an interval manner. The large modulus filler layer arranged on the inner side can play a clamping role of the small modulus filler layer arranged on the relatively outer side, avoiding the problem of falling off due to fracture.

[0051] As Figure 2 In some embodiments of the present application, the case of a double-layer conductive mesh layer is disclosed, at this time, the opposite sides of the first mesh layer 11 and the second mesh layer 12 are connected by the second filler layer 22, and other filler layers are further filled on the opposite sides of the first mesh layer 11 and the second mesh layer 12, thereby forming a multi-conductive mesh layer composite structure.

[0052] Of course, the structure based on more layers of conductive mesh layer should also be covered within the protection scope of the present application.

[0053] In addition, the present application also discloses an energy storage device such as a lithium battery prepared based on the above-mentioned composite current collector, a preparation method and process thereof can be prepared according to the traditional lithium battery

[0054] In the description of the present application, it should be understood that the orientations or positional relationships indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like are based on the orientations or positional relationships shown in the drawings or conventional expressions in the prior art, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0055] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which means that there are three cases of A, A and B, and B. In addition, the character " / " in this paper generally represents a "or" relationship between the front and rear associated objects.

[0056] The "multiple" appearing in the present application refers to two or more (including two), and similarly, "multiple groups" refers to two or more groups (including two groups), and "multiple pieces" refers to two or more pieces (including two pieces).

[0057] The above merely describes a preferred specific implementation of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art, within the technical range disclosed by the present application, according to the technical scheme and the inventive concept of the present application, makes equivalent replacements or changes, which should be encompassed in the protection scope of the present application.

Claims

1. A composite current collector, comprising: a composite support layer, the composite support layer comprising a conductive mesh layer and a filler layer filled in the pores of the conductive mesh layer; and a conductive layer disposed on at least one surface of the composite support layer; characterized in that the filler layer is provided as two or more composite filler layers, at least one of the composite filler layers having a greater elastic modulus than the other filler layers. The thickness of the conductive mesh layer is 6-300 μm. The conductive mesh layer is a metal mesh or a foamed metal.

2. The composite current collector of claim 1, wherein The metal mesh has a mesh count of 20-1000 mesh.

3. The composite current collector of claim 1, wherein The foamed metal has a porosity of 85%-98%. The thickness of the conductive layer is 0.1-2 μm. The filler layer is made of a polymer material.

4. The composite current collector of claim 1, wherein Some of the filler layers are provided with fillers.

5. The composite current collector of any one of claims 1-4, wherein, The fillers are thermally conductive fillers.

6. The composite current collector of claim 5, wherein The total thickness of the filler layer having a greater elastic modulus is 0.6-0.8 times the thickness of the conductive mesh layer.

7. The composite current collector of claim 6, wherein The filler layer having a greater elastic modulus is disposed on the inner side of the conductive mesh layer.

8. The composite current collector of any one of claims 1-4, 6, 7, wherein, The composite current collector of claim 9 is included.

9. The composite current collector of claim 8, wherein, ​ 10. An energy storage device, characterized by, ​

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