Novel strategy for high-performance supercapacitors through the polyvinylpyrrolidone (PVP)-assisted growth of FeS.

Iron disulfide or pyrite (FeS) has emerged as a promising transition metal sulfide-based supercapacitor owing to its abundance and superb electrochemical properties. However, FeS still faces major hurdles in realizing its full potential, such as a low energy density and poor conductivity. In this study, we report a high-performance FeS supercapacitor synthesized by a direct one-step process with the help of polyvinylpyrrolidone (PVP). The incorporation of PVP on the active materials prevented dendritic expansion and acted as a binding for solving the current FeS limitations, while facilitating a one-step synthesis process. Additionally, PVP could enhance the electrochemical performance by enabling faster ion movement. An FeS/PVP nanocomposite was successfully synthesized, and used in an asymmetric supercapacitor, demonstrating a high specific capacity of 735 F g (at 2 A g) and a high energy density of 69.74 W h kg (at 911 W kg). The superior electrochemical properties of FeS/PVP were enabled by the lower charge-carrier resistance and better surface passivation by PVP, as demonstrated by both electrochemical experiments and first-principles calculations. The high-performance supercapacitor of FeS presented in this study synthesized by an efficient method provides a new insight into novel supercapacitor electrodes.