Spiny Spherical Nickel–Cobalt Bimetallic Sulfide Nanocomposite for High-Energy-Density Pseudocapacitor

Multicomponent transition-metal sulfide is a potential electrode material for pseudocapacitors due to its excellent conductivity and high capacitance. Since the morphology and preparation method of electrode materials greatly affect the performance of capacitors, the development of novel structured multimetal sulfide is of great significance. Herein, we prepare Ni,Co–S materials by hydrothermal method and obtain diverse morphologies by changing the ratio of Ni, Co, and thiourea in the precursors. The Ni,Co–S exhibits optimum capacitance performance with a precursor mass ratio of 1:2:2 for Ni, Co, and thiourea. The discharge specific capacitances of Ni,Co–S at 1 and 20 A·g–1 in 6.0 mol·L–1 KOH are 1641 and 1406 F·g–1, respectively. In addition, the assembled asymmetric supercapacitor using Ni,Co–S and NPHTCK as bipolar shows a high energy density of 44.7 Wh·kg–1 at a power density of 800 W·kg–1.