Flexible, Thin-Layer Solid-State Supercapacitor Based on V_2O_5-Graphene Composite Electrode and Ionic Liquid Gel Polymer Electrolyte for Portable Electronic Systems

摘要

Supercapacitors long recognized for high power electrical energy storage have in the recent years received considerable stimulus as a preferred power source for use in wearable, portable and disposable medical electronic devices. Unified integration with such devices requires flexible supercapacitors in the solid-state planar format with high energy-power capacity. In this quest, transition metal (hydro) oxides MnO_2, V_2O_5, RUO_2 etc. displaying fast and reversible Faradaic surface and bulk redox reactions are most striking but least investigated as solid-state flexible supercapacitors. The key impediments have been the intrinsic low electrical conduction and reductive dissolution at lower cathodic voltages in presence of hydroxyl ions which are common in most past reported polymer gel electrolytes. These factors restrain the metal oxide supercapacitors from achieving their potential performance. In this research, we demonstrate high (1700-1920 Fg-1) specific capacity symmetrical flexible supercapacitor based on sol-gel processed V_2O_5-graphne composite electrode configured over stainless steel foil substrate using ionic liquid gel electrolyte. Flexible stainless steel foil substrate has high conductivity and offers both flexibility and strength.