Vanadium disulfide nanosheets loaded on carbon cloth as electrode for flexible quasi-solid-state asymmetric supercapacitors: energy storage mechanism and electrochemical performance

Abstract

Supercapacitors have excellent current discharge capacity and high energy conversion efficiency, and compared with other energy storage devices they cause little pollution in the environment. However, they generally exhibit lower energy density. Herein, vanadium disulfide (VS₂) nanosheets are grown on the surface of carbon cloth (CC) with a large specific surface area by a hydrothermal method to form a highly open network, which effectively promotes charge transfer and improves energy density. The synergistic effect of CC with double-layer capacitance characteristics and VS₂ with pseudocapacitance characteristics is fully realized for enhancing the electrochemical performance. The specific capacitance of VS₂/CC is 972.5 mF cm⁻² at 1 mA cm⁻², and the capacitance retention is 77.5% after 10 000 charge and discharge cycles at 10 mA cm⁻². Furthermore, an asymmetric supercapacitor based on VS₂/CC-12 and activated carbon (AC/CC) was also assembled. The asymmetric supercapacitor possesses a higher energy density of 0.22 mW h cm⁻² at 4.24 mW cm⁻². When the power density increases to 8.26 mW cm⁻², the energy density is still 0.16 mW h cm⁻². This demonstrates that VS₂/CC composites have great potential applications as flexible supercapacitor electrode materials.