Graphene networks for high-performance flexible and transparent supercapacitors

Graphene network (GN) was synthesized by a two-step chemical vapour deposition (CVD) method, involving the thermal annealing sputter-coated Cu film to form a Cu network by annealing for CVD deposition of graphene onto the Cu network catalyst. The resultant graphene network was transferred onto a flexible and transparent polymer (e.g., PDMS) substrate while maintaining its porous structure and integrated interconnection, providing both good optical transparency (e.g., transmittance of 86% at 550 nm wavelength) and mechanical flexibility. Flexible and transparent all-solid-state supercapacitors based on the newly-developed graphene network were fabricated to exhibit an area specific capacitance of 4.2 μF cm⁻² at a discharge current of 0.1 μA with a high optical transparency (transmittance of 84%), which outperforms devices based on uniform multi-layer graphene sheet.