Microflower-like CuS/Co3S4 composite as high-capacity and excellent-stability material for hybrid supercapacitors

Recently, transition metal sulfides (TMSs) have attracted great attention because of their abundant valence states and remarkable electrochemical activity in the field of supercapacitors. However, it is still a great challenge to prepare TMSs with high specific capacitance, good rate performance, and remarkable cycle stability. Herein, the microflower-like CuS/Co ₃S ₄ composite was achieved through an efficient two-step procedure. Firstly, the microflower-like CuCo precursors consisting of ultrathin nanoflakes were prepared by a simple solvothermal reaction. Subsquently, the CuS/Co ₃S ₄ composites with microflower-like microstructure, rich in nanoflakes, almost the same with the precursors, were obtained using Na ₂S·9 H ₂O as the sulfur source through a simple hydrothermal treatment. Ascribing to the distinctive microflower structure and bimetallic sulfides synergy, the CuS/Co ₃S ₄ electrode shows a notable specific capacitance (1483 F g ⁻¹ at 1 A g ⁻¹) and an impressive rate performance (1038.1 F g ⁻¹ at 20 A g ⁻¹). Furthermore, the assembled hybrid supercapacitor CuS/Co ₃S ₄//PC displays a considerable energy density of 55.02 Wh kg ⁻¹ at the power density of 372.5 W kg ⁻¹, and a distinguished cycle performance. This study provides valuable insights into the development of novel bimetallic sulfides for potential application in supercapacitors.