Direct growth of porous vanadium nitride on carbon cloth with commercial-level mass loading for solid-state supercapacitors

Abstract

Mass production of wearable devices with effective three-dimensional (3D) structure is a vital prerequisite for practical energy storage. Vanadium nitride (VN) has been identified as a promising supercapacitor electrode due to its wide negative potential working window, high specific capacitance and outstanding electrical conductivity, Herein, porous VN is grown on carbon cloth (CC) by a dip-coating and nitridation method. Such a VN/CC electrode provides effective 3D structure is beneficial for high mass loading (up to 28.3 mg cm−2) with high specific capacitance. Consequently, the as-prepared VN/CC electrode can achieve high areal capacitance of 3.34 F cm−2 at 5 mA cm−2. As a result, the flexible symmetric supercapacitor shows robust cycling stability (96% retention over 10,000 cycles) with PVA/KOH gel electrolyte. In addition, high energy/power density (0.341 mWh cm−2 at 1.92 mW cm−2) and excellent cycling performance (87% retention over 8000 cycles) are achieved in the assembled solid-state asymmetric supercapacitor cell with Zn−Ni−Co ternary oxides (ZNCO)/NF cathode and VN/CC anode. The results provide a simple route to prepare high mass loading porous VN-based electrodes with outstanding areal capacitance. It is believed that this strategy will favor the development of other transition metal nitride electrodes for commercial use in the future.