CURRENT COLLECTORS AND ENERGY STORAGE DEVICES
In a first aspect, a current collector includes a polymer film, a first metal layer adhered to the polymer film, and a second metal layer adhered to the polymer film on a side opposite the first metal layer. The polymer film includes an electrically conductive filler and has a surface resistivity of 1 Megaohm/square or less. The first and second metal layers each have a thickness of 3 μm or less. The current collector has a mid-discharge voltage that is at least 20% lower when compared to an untreated battery-grade copper foil, based on a standard lithium-ion battery half-cell test at a temperature of 25° C. and discharge rate of 2 C or greater.
1 . A current collector comprising a polymer film, a first metal layer adhered to the polymer film, and a second metal layer adhered to the polymer film on a side opposite the first metal layer, wherein:
the polymer film comprises an electrically conductive filler and has a surface resistivity of 1 Megaohm/square or less;
the first and second metal layers each have a thickness of 3 μm or less; and
the current collector has a mid-discharge voltage that is at least 20% lower when compared to an untreated battery-grade copper foil, based on a standard lithium-ion battery half-cell test at a temperature of 25° C. and discharge rate of 2 C or greater.
2 . The current collector of claim 1 , wherein the polymer film comprises a polymer comprising an imide group.
3 . The current collector of claim 2 , wherein the polymer is selected from the group consisting of polyimides, poly(amide-imides), poly(ester-imides) and poly(amide-ester-imides).
4 . The current collector of claim 1 , wherein the polymer film comprises a multilayer film comprising:
a first outer layer comprising a first polymer;
a second outer layer comprising a second polymer; and
a core layer comprising a third polymer, wherein the core layer is between the first and second outer layers and the electrically conductive filler is present in one or more of the layers.
5 . The current collector of claim 4 , wherein one or more of the first, second and third polymers comprises a polymer comprising an imide group.
6 . The current collector of claim 4 , wherein the first and second polymers are the same.
7 . The current collector of claim 1 , wherein the electrically conductive filler is an inorganic filler, an organic filler or a mixture thereof.
8 . The current collector of claim 7 , wherein the electrically conductive filler is carbon black.
9 . The current collector of claim 1 , wherein the electrically conductive filler is present in the polymer film at a concentration in a range of from 5 to 65 weight percent based on the total weight of the polymer film.
10 . An energy storage device comprising the current collector of claim 1 .
11 . The energy storage device of claim 10 , wherein the energy storage device is selected from the group consisting of lithium-ion batteries, capacitors, super capacitors, fuel cells and redox flow batteries.