Mesoporous nanohybrids of 2D layered Cu–Cr phosphate and rGO for high-performance asymmetric hybrid supercapacitors

Abstract

Asymmetric hybrid supercapacitors (AHSs) with wide operating voltage windows can be developed by effectively combining electric double-layer capacitor- and battery-type electrodes while maintaining their excellent cycling stabilities. In this study, the hybridization of two-dimensional Cu–Cr phosphate (CCP) with layered reduced graphene oxide (rGO) is achieved to develop a high-performance AHS. CCP and rGO are combined into CCP/rGO (CCPG) nanohybrids by a simple and inexpensive single-step chemical method. The CCPG nanohybrids prepared with an optimal amount of rGO exhibit mesoporosity with high surface areas (40 m2/g) and fast charge transfer kinetics. The optimized CCPG delivers a higher specific capacity of 1620 C/g than CCP (694 C/g) in a three-electrode configuration at a current density of 1 A/g. When fabricated using the CCPG and rGO, the AHS exhibits a high specific capacity of 177 C/g, high specific energy of 65.14 Wh/kg, high specific power of 826 W/kg at 1 A/g, and outstanding cyclic stability (94%) within the widened potential window (1.6 V) in aqueous electrolyte. This study suggests that conducting rGO plays a crucial role in the formation of high-performance CCPG nanohybrids, and consequently, the resulting CCPG electrode demonstrates considerably enhanced physiochemical and electrochemical properties, compared with the CCP electrode. Through this hybridization approach, various nanohybrids of other metal dichalcogenide phosphates and rGO can also be developed.