High rate capability electrode constructed by anchoring CuCo2S4 on graphene aerogel skeleton toward quasi-solid-state supercapacitor

Abstract

Designing nano-scale electrode materials has been proven to be an efficient path for enhancing the rate capability and stability of supercapacitors. Herein, a novel electrode is designed by anchoring copper cobalt sulfide (CuCo2S4) nanoparticles on the graphene aerogel (GA) via a facile solvothermal method. The CuCo2S4 particles with an average size of 21 nm can guarantee the abbreviated ion diffusion paths and the GA can ensure a conductive skeleton and prevent CuCo2S4 from agglomeration, thus promoting kinetics and efficiency of electrochemical process synchronously. As a result, the CuCo2S4/GA electrode exhibits a high specific capacitance of 668 F g−1 at a current density of 1 A g−1 along with 72% retention as the current increases to 20 A g−1, showing a decent rate capability. The measurable analysis of charge storage reveals that the surface capacitive process plays a dominant role during the electrochemical process and its proportion raises with the increase of the scan rate, resulting in excellent rate capability. Additionally, a quasi−solid−state supercapacitor is assembled by using CuCo2S4/GA composite as the free-standing electrode, which delivers an energy density of 22 W h kg−1 together with a power density of 1080 W kg−1, implying the potential application in supercapacitors.