The supercapattery designed with a binary composite of niobium silver sulfide (NbAg 2 S) and activated carbon for enhanced electrochemical performance.

A supercapattery is a hybrid device that is a combination of a battery and a capacitor. Niobium sulfide (NbS), silver sulfide (Ag 2 S), and niobium silver sulfide (NbAg 2 S) were synthesized by a simple hydrothermal method. NbAg 2 S (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 Ag 2 S (232 C g -1 ), as determined by the electrochemical investigation of a three-cell assembly. Activated carbon and NbAg 2 S were combined to develop the asymmetric device (NbAg 2 S//AC). A maximum specific capacity of 142 C g -1 was delivered by the supercapattery (NbAg 2 S//AC). The supercapattery (NbAg 2 S/AC) provided 43.06 W h kg -1 energy density while retaining 750 W kg -1 power density. The stability of the NbAg 2 S//AC device was evaluated by subjecting it to 5000 cycles. After 5000 cycles, the (NbAg 2 S/AC) device still had 93% of its initial capacity. This research indicates that merging NbS and Ag 2 S (50/50 wt% ratio) may be the best choice for future energy storage technologies.