Role of anion on the electrochemical performance of MnCo chalcogenides

Transition metal chalcogenides (TMCs) own multiple oxidation states and enhanced electroactivities of metal centres. To reveal the influence of anions in TMCs on the electrochemical performance of these promising supercapacitor electrode materials, three manganese and cobalt chalcogenides, namely MCS, MCSe, and MCTe are synthesized and characterized. In alkaline electrolytes, the capacities at a current density of 1 A g−1 are 920.5, 529.9, and 131.3C g−1, respectively. MCS exhibits a superior specific capacity, enhanced rate capability, and long-term cycling stability. Consequently, anions of S, Se and Te determine electrochemical performance of TMCs. An ensembled quasi-solid asymmetric supercapacitor, consisting of the MCS cathode and an anode of a holey reduced graphene oxide (hrGO) coupled with 2,2,6,6-Tetramethylpiperidin-1-oxyl (TEMPO) possesses a maximum energy density of 43.7 Wh kg−1 at a power density of 750.3 W kg−1 or a maximum power density of 14,898.6 W kg−1 at an energy density of 15.3 Wh kg−1. It retains 98.3 % of initial capacity even after 7500 charge/discharge cycles at a current density of 10 A g−1. This study provides insight into the synthesis and utilization of TMCs for the ensemble of high-performance supercapacitors.