Rose-like Ni3S4 as battery-type electrode for hybrid supercapacitor with excellent charge storage performance

Rose-like Ni3S4 microflowers are successfully synthesized by a novel two-step hydrothermal technique. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterization are used to identify the spinel structure and rose-like morphology of the synthesized Ni3S4. The cyclic voltammetry and galvanostatic charge–discharge tests demonstrate improved electrochemical performance. The Ni3S4 microflower shows enhanced pseudocapacitive performance of approximately 1797.5 F g−1 at a current density of 0.5 A g−1, and the kinetic analysis reveals a diffusion controlled faradaic characteristic of Ni3S4 (28.66% capacitive contributions). Moreover, a hybrid supercapacitor is successfully assembled with Ni3S4 as the positive electrode and active carbon (AC) as the negative electrode. The Ni3S4//AC device exhibits a relatively high energy density of 18.625 Wh kg−1, a maximum power density of 1500.2 W kg−1 as well as an excellent cycling performance (approximately 93% capacitance retention over 5000 cycles).