Hybrid Co3O4/Co9S8 Nanowires for High-Performance Asymmetric Supercapacitors

We successfully synthesize hierarchical Co3O4@Co9S8 nanowires on nickel foam by a facile two-step method. The as-prepared samples show one-dimensional nanowires decorated with uneven surface after vulcanization process with pure Co3O4 nanowires to form Co3O4@Co9S8 composite, which exhibit high specific capacitance of 2667 F g(-1) at 12 A g(-1), maintaining 76.78% capacitance retention of initial capacitance. The assembled asymmetric supercapacitor (ASC) device shows excellent capability of energy storage and power output with an energy density of 267.9 mW h cm(-3) at power density of 7.5 W cm(-3) and 187.5 mW h cm(-3 )at 15 W cm(-3). In addition, it exhibits excellent cycling capability with 84.2% retention after 6000 cycles. Therefore, the as-prepared material can be used as promising energy storage materials.