Nanocubic transition metal sulfides (FeMn)S2@NC synthesized by MOFs facily for supercapacitors

Abstract

Transition metal sulfides have attracted considerable attention as supercapacitor materials due to their favorable electrochemical properties and low cost. However, challenges such as slow electrochemical kinetics and significant volume changes still persist. In this study, (FeMn)S₂@NC nanocubes were synthesized by utilizing MOFs as precursors, employing a solution method to encapsulate Ppy around the periphery, followed by a one-step annealing process. The electrode prepared from (FeMn)S2@NC exhibits a high specific capacitance of 1154 F/g at 1 A/g and retains a specific capacitance of 777 F/g even at a high current density of 5 A/g. After 8000 charge-discharge cycles at 10 A/g, it still maintains a high capacity retention of 94 % and close to 100 % Coulombic efficiency. The (FeMn)S2@NC//AC capacitor exhibite excellent electrochemical performance with good rate capability and practical value 39.73F/g at 1A/g, 38.26F/g at 2A/g, 26.67F/g at 5A/g, 20.53F/g at 7A/g and 14F/g at 10A/g. Electrochemical testing at 5A/g show 93.3 % high capacity retention after 180,000 cycles.