Honeycomb-like Ni3S2 nanosheet arrays for high-performance hybrid supercapacitors

Supercapacitors have attracted great attention as advanced energy storage devices. However, the low energy density and high cost of electrode materials are the downsides for their practical applications. Here, we introduce a facile and low-cost strategy to develop honeycomb-like Ni3S2 nanosheet arrays (NSAs) as a redox-type electrode for aqueous hybrid supercapacitors (HSCs). Owing to the porous structure of NSAs, the Ni3S2 electrode can show excellent electrochemical performance in 2 M KOH aqueous electrolyte. A high specific capacity of 151.2 mAh g−1 has been achieved at the current density of 3 A g−1. To demonstrate their further applications, HSCs have been assembled with activated carbon (AC) as negative electrode and the assembled devices can successfully work within a large voltage range of 0–1.6 V and deliver a maximum energy density of 35.2 Wh kg−1 at the power density of 491 W kg−1.