Facile template-free synthesis of mesoporous cobalt sulfide for high-performance hybrid supercapacitors

A high-capacity and mesopore-rich electrode material is crucial for constructing hybrid supercapacitors (HSCs) with high energy densities. Developing mesopore-rich cobalt sulfides can increase the effective contact area for surface redox reactions. However, incorporating mesopores in metal sulfides is challenging owing to the low affinity between metals and sulfur. Herein, a simple strategy to fabricate mesoporous cobalt sulfide (mp-Co3S4) was proposed. The mp-Co3S4 exhibited the specific capacities of 246.2 mAh g(-1) (at a current density of 1 A g(-1)) and delivered remarkable energy and power densities (32.5 Wh kg(-1) and 596.94 W kg(-1), respectively) when used as an electrode for an HSCs device, showing an excellent cycle life and capacity retention of 84% after 3000 cycles. In addition, unique structure of the fabricated mp-Co3S4 provided sufficient electrochemically active sites and enhanced the cycle stability of the constructed HSC device. This template-free synthesis of mp-Co3S4 can be used to fabricate other transition metal sulfides.