Shell-strengthened hollow architecture of NiCo2S4 carved through an in-situ reaction Ostwald Ripening mechanism with significantly enhanced electrochemical performance

For Faraday supercapacitors , some battery-type electrode materials such as nickel-based materials attract intensive attention by virtue of their high theoretical capacity. However, it is quite difficult for these materials to achieve the satisfied high-rate performance and cycling life concurrently due to the contradiction of their individual requirements to the microscopic structure of materials. In this work, we build a hollow architecture of NiCo 2 S 4 at hydrothermal condition following an in-situ reaction Ostwald Ripening mechanism. The as-prepared NiCo 2 S 4 presents a shell-strengthened hollow structure, satisfying the as-mentioned two requirements: (1) the rich pores in shell and hollow structure plus structural cobalt ions lead to the excellent high-rate performance of NiCo 2 S 4 ; (2) the dense particulate layer in shell with additional mechanical strength prolongs the cycling life of NiCo 2 S 4 . Consequently, the asymmetrical supercapacitors assembled with NiCo 2 S 4 as positive electrode material show both high energy and power densities, and excellent cycling stability.