Boosting Charge Storage and Oxygen Evolution Kinetics through Li+ Doping in Co9S8/Ni9S8 Materials

Abstract With the continuous development of society and the improvement of living standards, the need for renewable resources has become increasingly urgent. In the field of electrochemical energy storage systems, supercapacitors garner significant attention due to their rapid charging and discharging capabilities, high power density, and environmentally friendly nature. However, the effectiveness of electrocatalytic reactions largely depends on the kinetics of the hydrogen evolution reaction and oxygen evolution reaction (OER). This study explores the impact of Li+ doping on the electrochemical properties of Co9S8/Ni9S8 materials. Li-Co9S8/Ni9S8 is successfully synthesized via a two-step hydrothermal method, and the Li-Co9S8/Ni9S8-0.3 material demonstrates a mass specific capacitance of 855 F g−1 at a current density of 0.5 A g−1. The assembled asymmetric supercapacitor achieves a power density of 4050 W kg−1 at an energy density of 86.7 Wh kg−1. In a 1.0 M KOH electrolyte, the Li-Co9S8/Ni9S8-0.3 material exhibits efficient OER performance, with an overpotential of 191.4 mV at a current density of 20 mA cm−2. Moreover, the material exhibits a low battery voltage of 1.50 V at 20 mA cm−2 and maintains excellent stability over 30 h of cycling.