Enhancing redox kinetics by electron orbital modulation for high-performance aqueous energy storage

The energy density of supercapacitors can be improved through rapid surface reconstruction of electrode materials in an alkaline medium. Transition metal sulfides (TMSs), including Co 9 S 8 , are widely used as energy storage electrode materials owing to their excellent structural characteristics. However, systematic research dealing with the enhancement of Co 9 S 8 reconstruction ability induced by Se doping has not well been investigated. Herein, an electron orbital modulation strategy was developed to promote the reconfiguration capability of Co 9 S 8 by substitution of the Se element. The theoretical simulation and experimental characterization confirmed the successful introduction of the Se element, resulting in more polarized charge distribution in Co 9 S 8 and better charge transfer ability. The improved adsorption capacity of OH − also enhanced the intensity of surface reactions, as well as effectively increased the refactoring rate. The optimized Co 9 S 5.1 Se 2.9 exhibited a specific capacitance of 1788.1 F g −1 at 1 A g −1 . The assembled flexible asymmetric supercapacitor delivered a maximum energy density of 54.9 Wh kg −1 . Overall, the proposed strategy can effectively be used to construct high energy density electrode materials with optimized reconstruction of dynamic rates through effective modulation of electron orbitals.