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