Preparation of a Super Flexible Cu/Carbon Composite Nanofiber Film Electrode for High-Performance Flexible All-Solid-State Supercapacitors

A super flexible copper/carbon nanofiber film electrode is successfully synthesized through a calcination process wholly under nitrogen atmosphere. It is found that the heating rate in the calcination process plays a crucial role in achieving foldable super flexibility. The as-obtained film electrode exhibits mechanical super flexibility with a maximum specific capacitance of 608 F g −1 at a current density of 1 A g −1 and a capacity retention of 75.7% after 1000 cycles. Its flexible symmetric all-solid-state supercapacitor shows a superior areal capacitance of 88 mF cm −2 at a current density of 0.2 mA cm −2 and a high energy density of 41 μWh cm −2 at a power density of 0.28 mW cm −2 .