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.