Secondary battery current collector and secondary battery

Abstract

The invention discloses a current collector of a secondary battery and the secondary battery. The current collector comprises an insulating support layer and two laminated structures. The insulating support layer has a first surface and a second surface opposite to the first surface. The two laminated structures are respectively arranged on the first surface and the second surface; wherein each laminated structure comprises a metal layer and a first conductive composite layer which are overlapped, the resistivity of the metal layer is less than or equal to 1 * 10 <-7 > omega.m, the first conductive composite layer comprises a composite material, a coupling material and a bonding material, and the composite material comprises graphene and a carbon-based material.

Description

Technical Field

[0001] The present invention relates to a current collector, and in particular to a current collector of a secondary battery and a secondary battery. Background Art

[0002] Secondary batteries are also called rechargeable batteries. For example, lithium-ion batteries have been continuously improving in performance since their introduction in 1990. They have been widely used in products such as computers, communications, and consumer electronics over the past two decades, and have had a great impact on human society. In addition, in order to reduce human dependence on petrochemical and coal fuels, reduce pollution emissions, and mitigate global warming, various lithium-ion battery vehicles, solar energy, and wind power renewable energy have become the focus of development in advanced countries around the world. Due to the rich variety of positive and negative electrode materials of lithium-ion batteries, lithium-ion batteries can exhibit excellent characteristics in different usage scenarios. Judging from the current development trend, lithium-ion batteries have also become the mainstream of large-scale power storage systems required for secondary batteries and energy storage applications.

[0003] In lithium-ion batteries, the role of the current collector is to serve as a conductor and support for concentrated power generation when the battery is charged and discharged. Taking copper foil as the current collector, various research institutions have continued to study the current collector coated with carbon-based conductive materials on copper foil. However, whether copper foil is used or carbon-based conductive materials are coated on copper foil as the current collector, when the battery is pierced by foreign objects, it will cause considerable safety problems, such as short circuit of the current collector causing the battery to burn or explode. In addition, because the copper foil used in existing current collectors is relatively thick (e.g. 8 to 10 microns) and heavier, it will also reduce the weight energy density of the battery.

[0004] Therefore, how to provide a current collector and a secondary battery that can improve safety while also improving the weight energy density of the battery is one of the issues that the industry attaches great importance to. Summary of the invention

[0005] In view of the above problems, an object of the present invention is to provide a current collector of a secondary battery and a secondary battery, which can improve the safety and weight energy density of the battery.

[0006] To achieve the above-mentioned purpose, the present invention provides a current collector of a secondary battery, comprising an insulating support layer and two laminated structures. The insulating support layer has a first surface and a second surface opposite to the first surface. The two laminated structures are respectively arranged on the first surface and the second surface; wherein each laminated structure comprises an overlapping metal layer and a first conductive composite layer, and the resistivity of the metal layer is ≤1x10 -7Ω·m, and the first conductive composite layer includes a composite material, a coupling material and a bonding material, and the composite material includes graphene and a carbon-based material.

[0007] In one embodiment, the material of the insulating support layer includes polyethylene terephthalate, polyimide or polypropylene, or a combination thereof.

[0008] In one embodiment, the material of the metal layer includes copper or aluminum.

[0009] In one embodiment, the carbon-based material includes graphene, nanocarbon black, carbon nanotubes or carbon nanofibers, or a combination thereof.

[0010] In one embodiment, the composite material accounts for 55 wt % to 70 wt % of the first conductive composite layer.

[0011] In one embodiment, the coupling material is a silane coupling agent, and the content of the silane coupling agent is between 5 wt % and 10 wt % of the first conductive composite layer.

[0012] In one embodiment, the bonding material includes acrylic, epoxy, polyacrylonitrile, polyvinyl pyrrolidone, polyvinyl alcohol or methyl cellulose, or copolymers thereof.

[0013] In one embodiment, the content of the bonding material is between 20 wt % and 40 wt % of the first conductive composite layer.

[0014] In one embodiment, the metal layer is sandwiched between the first conductive composite layer and the insulating support layer.

[0015] In one embodiment, the first conductive composite layer is sandwiched between the metal layer and the insulating support layer.

[0016] In one embodiment, each stacked structure further includes a second conductive composite layer, and each metal layer is sandwiched between each second conductive composite layer and each first conductive composite layer.

[0017] To achieve the above object, the present invention also provides a secondary battery, comprising the above-mentioned collector, two first electrodes, two second electrodes and two separators. The collector has two opposite surfaces. The two first electrodes are respectively arranged on the two surfaces of the collector. Each second electrode is arranged on a side of each first electrode away from the collector. Each separator is arranged between each first electrode and each second electrode.

[0018] In one embodiment, the material of the first electrode includes copper, and the material of the second electrode includes aluminum.

[0019] In one embodiment, the material of the first electrode includes aluminum, and the material of the second electrode includes copper.

[0020] In one embodiment, each first electrode is a copper foil, the secondary battery further includes two third conductive composite layers, and each third conductive composite layer is disposed on a surface of each isolation film facing each first electrode.

[0021] As described above, in the current collector and the secondary battery of the present invention, two laminated structures are respectively arranged on the first surface and the second surface of the insulating support layer, each laminated structure includes an overlapping first conductive composite layer and a metal layer, and the resistivity of the metal layer is ≤1x10 -7 Ω·m, and the first conductive composite layer includes a composite material, a coupling material and a bonding material, and the composite material includes a structure and material design of graphene and a carbon-based material. When the collector of the present invention is applied to a secondary battery and is penetrated by a foreign object, the collector can reduce or cut off the short-circuit current from the material level (insulating support layer), thereby improving the safety of the battery. In addition, since the organic material density of the collector is low, the weight energy density of the battery can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 FIG. 1 is a schematic diagram of a current collector of a secondary battery according to an embodiment of the present invention.

[0023] Figure 2 and Figure 3 They are schematic diagrams of current collectors according to different embodiments of the present invention.

[0024] Figure 4 and Figure 5 They are partial schematic diagrams of secondary batteries according to different embodiments of the present invention. DETAILED DESCRIPTION

[0025] The following will refer to the relevant drawings to illustrate the collector and secondary battery of some embodiments of the present invention, wherein the same components will be described with the same reference symbols. The components appearing in the following embodiments are only used to illustrate their relative relationships and do not represent the proportions or sizes of the actual components.

[0026] Figure 1 Schematic diagram of a current collector of a secondary battery according to an embodiment of the present invention.

[0027] like Figure 1 As shown, the current collector 1 of the secondary battery of this embodiment includes an insulating support layer 11 and two laminated structures 12 .

[0028] The insulating support layer 11 has a first surface 111 and a second surface 112 opposite to the first surface 111. In some embodiments, the material of the insulating support layer 11 may include, for example but not limited to, polyethylene terephthalate (PET), polyimide (PI) or polypropylene (PP), or a combination thereof, and the thickness of the insulating support layer 11 may be, for example but not limited to, 3 micrometers (μm).

[0029] The two stacked structures 12 are respectively disposed on the insulating support layer 11 and are respectively in direct contact with the first surface 111 and the second surface 112 of the insulating support layer 11. Each stacked structure 12 includes an overlapping first conductive composite layer 121 and a metal layer 122. In this embodiment, the metal layer 122 is sandwiched between the first conductive composite layer 121 and the insulating support layer 11. The resistivity of the metal layer 122 is ≤ 1x10 -7 Ω·m. In some embodiments, the material of the metal layer 122 may include copper or aluminum. In some embodiments, the metal layer 122 used for the negative electrode may be, for example, copper foil, and the metal layer 122 used for the positive electrode may be, for example, aluminum foil. In some embodiments, the preferred thickness of the metal layer 122 may be, for example, 1 μm.

[0030] The first conductive composite layer 121 includes a composite material, a coupling material and an adhesive material. Among them, the composite material may include graphene and a carbon-based material, and the proportion is not limited. Here, the carbon-based material may include graphene, nanocarbon black, nanocarbon tubes or nanocarbon fibers, or a combination thereof. In other words, a carbon-based material of graphene, nanocarbon black, nanocarbon tubes or nanocarbon fibers, or a combination thereof is added to graphene to form the aforementioned composite material (i.e., a graphene carbon-based composite material). In some embodiments, the content of the composite material may account for between 55wt% and 70wt% of the content of the first conductive composite layer 121, and preferably 65wt%, for example.

[0031] The coupling material may be, for example, but not limited to, a silane coupling agent. In some embodiments, the content of the silane coupling agent may be between 5wt% and 10wt% of the content of the first conductive composite layer 121, preferably, for example, 9wt%. The bonding material may include, for example, acrylic acid, acrylic, epoxy, polyacrylonitrile (PAN), polyvinyl pyrrolidone (PVP), polyvinyl alcohol (PVA) or methyl cellulose (CMC), or a combination thereof, or a copolymer thereof. In some embodiments, the content of the bonding material may be between 20wt% and 40wt% of the content of the first conductive composite layer 121, preferably, for example, 26wt%.

[0032] As mentioned above, in the collector 1 of the present embodiment, two laminated structures 12 are respectively disposed on the first surface 111 and the second surface 112 of the insulating support layer 11, each of the laminated structures 12 comprises an overlapping first conductive composite layer 121 and a metal layer 122, the metal layer 122 is sandwiched between the first conductive composite layer 121 and the insulating support layer 11, and the resistivity of the metal layer 122 is ≤1x10 -7 Ω·m, and the first conductive composite layer 121 includes a composite material, a coupling material and a bonding material, and the composite material includes a structure and material design of graphene and carbon-based materials. When the collector 1 of this embodiment is applied to a secondary battery and is penetrated by a foreign object, the design of the collector 1 can reduce or cut off the short-circuit current from the material level (insulating support layer 11), thereby improving the safety of the battery. In addition, since the organic material density of the collector 1 is low, the weight energy density of the battery can be improved.

[0033] In addition, when applied to a secondary battery, since the upper and lower surfaces of the current collector 1 of this embodiment can be in contact with the negative electrode material or the positive electrode material, the high specific surface area of ​​the first conductive composite layer 121 can increase the adhesion between heterogeneous materials (i.e., the metal layer 122 and the negative electrode material, or the metal layer 122 and the positive electrode material), and at the same time improve the conductivity, improve the heat conduction and heat dissipation capacity, increase the heat radiation and heat dissipation function, and also improve the chemical corrosion resistance. In addition, the high density negative charge of the graphene contained in the first conductive composite layer 121 can also be used to prevent the formation of dendrites of lithium metal.

[0034] Figure 2 and Figure 3 They are schematic diagrams of current collectors according to different embodiments of the present invention.

[0035] like Figure 2 As shown, the collector 1a of this embodiment is substantially the same as the collector 1, and the main difference from the collector 1 is that the first conductive composite layer 121 of the collector 1a of this embodiment is sandwiched between the metal layer 122 and the insulating support layer 11. In this way, the short-circuit current can be reduced or cut off from the material level, the safety of the battery can be improved, the weight energy density of the battery can be improved, and the adhesion between the metal layer 122 and the insulating support layer 11 can be increased.

[0036] In some embodiments, the first conductive composite layer 121 may be disposed on the metal layer 122 or the insulating support layer 11 by coating, for example, by transfer, micro-dimpling, gravure coating, etc.

[0037] In addition, if Figure 3As shown, the current collector 1b of this embodiment is substantially the same as the current collector 1a, and the main difference from the current collector 1a is that each laminated structure 12 of the current collector 1b of this embodiment may further include a second conductive composite layer 123, and each metal layer 122 is sandwiched between each second conductive composite layer 123 and each first conductive composite layer 121. Here, the second conductive composite layer 123 and the first conductive composite layer 121 may have the same material composition, and the content ratio of each material may be the same or different, which is not limited by the present invention.

[0038] Figure 4 and Figure 5 They are partial schematic diagrams of secondary batteries according to different embodiments of the present invention.

[0039] Please refer to Figure 4 The secondary battery 2 of this embodiment is a lithium-ion battery and may include a current collector 21, two first electrodes 22, two second electrodes 23 and two isolation films 24. The current collector 21 has two opposite surfaces S1 and S2. The two first electrodes 22 are respectively disposed on the surfaces S1 and S2 of the current collector 21 and individually contact the surfaces S1 and S2 of the current collector 21. Each second electrode 23 is disposed on a side of each first electrode 22 away from the current collector 21. And each isolation film 24 is disposed between each first electrode 22 and each second electrode 23, whereby the isolation film 24 can separate the first electrode 22 from the second electrode 23 to prevent the two electrodes from contacting and short-circuiting.

[0040] The current collector 21 may be the current collector 1, 1a or 1b of the above-mentioned embodiment. The specific technical contents have been described in detail above and will not be further described here.

[0041] In some embodiments, the materials of the first electrode 22 and the second electrode 23 are different. The first electrode 22 may be a negative electrode, and its material may include copper, while the second electrode 23 may be a positive electrode, and its material may include aluminum; or, the first electrode 22 may be a positive electrode, and its material may include aluminum, while the second electrode 23 may be a negative electrode, and its material may include copper. In some embodiments, the negative electrode may be an electrode in which a highly conductive carbon material (such as graphite, lithium titanate, etc.) is coated on copper foil, while the positive electrode may be an electrode in which a lithium composite oxide (such as lithium, manganese, cobalt, nickel, iron phosphate, etc.) is coated on aluminum foil. In some embodiments, the isolation membrane 24 may be a microporous membrane made of a polyolefin compound, such as polyethylene (PE) or polypropylene (PP). In addition, in different embodiments, such as Figure 5As shown, the aforementioned conductive composite layer material (forming a third conductive composite layer 25) can be coated on the surface of the microporous isolation film 24 facing the first electrode 22 (copper foil), and the high-density negative charge of the graphene contained in the conductive composite layer can also be used to prevent the formation of dendrites of lithium metal, and the strength of the isolation film 24 can also be increased. In addition, the secondary battery 2 can also include an electrolyte (not shown) made by dissolving a lithium salt in an organic solvent.

[0042] In summary, in the current collector and the secondary battery of the present invention, two laminated structures are respectively disposed on the first surface and the second surface of the insulating support layer, each laminated structure comprises an overlapping first conductive composite layer and a metal layer, and the resistivity of the metal layer is ≦1x10 -7 Ω·m, and the first conductive composite layer includes a composite material, a coupling material and a bonding material, and the composite material includes a structure and material design of graphene and a carbon-based material. When the collector of the present invention is applied to a secondary battery and is penetrated by a foreign object, the collector can reduce or cut off the short-circuit current from the material level (insulating support layer), thereby improving the safety of the battery. In addition, since the organic material density of the collector is low, the weight energy density of the battery can be improved.

[0043] The above description is for illustrative purposes only and is not intended to be limiting. Any equivalent modifications or changes made thereto without departing from the spirit and scope of the present invention should be included in the appended claims.

Claims

1. A current collector for a secondary battery, comprising: An insulating support layer having a first surface and a second surface opposite to the first surface; as well as Two stacked structures are respectively disposed on the first surface and the second surface; Wherein, each of the laminated structures comprises an overlapping metal layer and a first conductive composite layer, and the resistivity of the metal layer is ≤1x10 -7 Ω·m, and the first conductive composite layer includes a composite material, a coupling material and a bonding material, and the composite material includes graphene and a carbon-based material. 2 . The current collector as claimed in claim 1 , wherein the material of the insulating support layer comprises polyethylene terephthalate, polyimide or polypropylene, or a combination thereof. The current collector as claimed in claim 1 , wherein the material of the metal layer comprises copper or aluminum. 4 . The current collector of claim 1 , wherein the carbon-based material comprises graphene, nanocarbon black, carbon nanotubes or carbon nanofibers, or a combination thereof. 5 . The current collector according to claim 1 , wherein the content of the composite material is between 55 wt % and 70 wt % of the first conductive composite layer. 6 . The current collector according to claim 1 , wherein the coupling material is a silane coupling agent, and the content of the silane coupling agent is between 5 wt % and 10 wt % of the first conductive composite layer.

7. The current collector of claim 1, wherein the binder material comprises acrylic acid, acrylic, epoxy resin, polyacrylonitrile, polyvinyl pyrrolidone, polyvinyl alcohol or methyl cellulose, or a copolymer thereof.

8. The current collector of claim 1, wherein the content of the binder material is between 20 wt% and 40 wt% of the first conductive composite layer.

9. The current collector of claim 1, wherein the metal layer is interposed between the first conductive composite layer and the insulating support layer.

10. The current collector of claim 1, wherein the first conductive composite layer is interposed between the metal layer and the insulating support layer. 11 . The current collector according to claim 10 , wherein each of the stacked structures further comprises a second conductive composite layer, and each of the metal layers is sandwiched between each of the second conductive composite layers and each of the first conductive composite layers.

12. A secondary battery comprising: The current collector according to any one of claims 1 to 11, wherein the current collector has two opposing surfaces; Two first electrodes are respectively disposed on the two surfaces of the current collector; two second electrodes, each of the second electrodes being arranged on a side of each of the first electrodes away from the current collector; as well as Two isolation films, each of which is disposed between each of the first electrodes and each of the second electrodes. 13 . The secondary battery according to claim 12 , wherein the material of the first electrode comprises copper, and the material of the second electrode comprises aluminum. 14 . The secondary battery according to claim 12 , wherein the material of the first electrode comprises aluminum, and the material of the second electrode comprises copper.

15. The secondary battery according to claim 12, further comprising: two third conductive composite layers; The third conductive composite layers are arranged on surfaces of the isolation films facing the first electrodes.

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