The supercapattery designed with a binary composite of niobium silver sulfide (NbAg2S) and activated carbon for enhanced electrochemical performance

Abstract

A supercapattery is a hybrid device that is a combination of a battery and a capacitor. Niobium sulfide (NbS), silver sulfide (Ag2S), and niobium silver sulfide (NbAg2S) were synthesized by a simple hydrothermal method. NbAg2S (50/50 wt% ratio) had a specific capacity of 654 C g−1, which was higher than the combined specific capacities of NbS (440 C g−1) and Ag2S (232 C g−1), as determined by the electrochemical investigation of a three-cell assembly. Activated carbon and NbAg2S were combined to develop the asymmetric device (NbAg2S//AC). A maximum specific capacity of 142 C g−1 was delivered by the supercapattery (NbAg2S//AC). The supercapattery (NbAg2S/AC) provided 43.06 W h kg−1 energy density while retaining 750 W kg−1 power density. The stability of the NbAg2S//AC device was evaluated by subjecting it to 5000 cycles. After 5000 cycles, the (NbAg2S/AC) device still had 93% of its initial capacity. This research indicates that merging NbS and Ag2S (50/50 wt% ratio) may be the best choice for future energy storage technologies.