One-step synthesis of NiCo2S4 with high electrochemical performance used for hybrid capacitor

Abstract Spinel sulfide NiCo2S4 (NCS) is one of the ternary metal sulfides, used as a promising electrode for hybrid capacitor, which is beneficial from its multi-active sites and good conductivity. In this study, NCS with sulfur vacancies was obtained through a one-step hydrothermal reaction. The morphology of NCS was regulated by adding a certain content of urea. Additionally, flower-like NCS was obtained when 10 mmol of urea was added, whose highest specific capacity performance was 453.40 C g−1 at 1 A g−1. Meanwhile, the as-prepared NCS electrode and activated carbon electrode were fabricated into hybrid capacitors. The energy density of such a device reached the highest value of 27.77 Wh kg−1, whereas the maximum power density was 13.34 kW kg−1. Moreover, this hybrid capacitor maintained the 62.07% of its initial capacity after 10 000 cycles at 2 A g−1, indicating that this one-step synthesized NCS has potential to be applied to long-serving energy storage device.