A Self-Improved High-Capacitance Supercapacitor Based on Unstacking of Reduced Graphene Oxide Assisted By Lithium Salts of Tungstosilicic Acid

摘要

Lithium salts of tungstosilicic acid (SiWLi) enriched with oxygen-containing functional groups were developed as an electrolyte for the prevention of reduced graphene oxide (rGO) restacking. The morphology and microstructure of SiWLi and rGO were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The composite of SiWLi and rGO were fabricated and utilized as electrodes to assemble supercapacitors, which displayed significantly enhanced capacitance. The initial specific capacitance of this supercapacitor is 203 F g~(-1) at 10 mV s~(-1). After 2300 cyclic voltammetry tests it grew up to 297 F g~(-1) at 10 mV s~(-1). In addition, this self-improved supercapacitor exhibited excellent rate performance after 2300 cyclic voltammetry tests. The achieved specific capacitance is 271 F g~(-1) at 200 mV s~(-1), which is much higher than that obtained in the initial test (173 F g~(-1) at 200 mV s~(-1)). The self-improved effect could be attributed to more activated rGO assisted by the synergistic electrochemical interaction between the electric double layer capacitance of rGO and the pseudocapacitance of SiWLi.