Al intercalated ZnS nanosheets as anode for supercapattery application with wide operating potential window

Abstract

Selection of electrode material and operating potential window are important factor affecting the specific capacitance, energy density and stability of energy storage devices. Pristine ZnS has attracted the researchers to be focused for electrochemical performance due to its high theoretical capacitance, easy fabrication, low cost and environmental friendliness. Herein, we report successful fabrication of Al intercalated ZnS (Al_1.6Zn_80.9S_17.5) nanosheets to optimize the structure, morphology and electrochemical performance as anode material for supercapattery application. Al-ZnS (Al_1.6Zn_80.9S_17.5) is operated at wider potential window −0.3 to 0.8 to achieve an excellent specific capacitance of 1414 Fg⁻¹ along with high energy density of about 90 Whkg⁻¹ at 6540 WKg⁻¹ power density, much higher than pristine ZnS (0 to 1.6 V, 705 Fg⁻¹). The different current controlling mechanisms has also been analyzed by theoretical study using Dunn’s differentiation method. The reported wide potential window offers the opportunity to develop asymmetric supercapattery device that can operate at broaden potential window. Furthermore, Al-ZnS//rGO supercapattery device operating at 1.5 V potential is constructed using Al-ZnS as anode and rGO as cathode. Al-ZnS//rGO supercapattery device demonstrates an excellent specific capacitance of approximately 250 Fg⁻¹ and energy density of about 140 Whkg⁻¹ at 5800 WKg⁻¹. The designed supercapattery device also exhibits 98 % columbic and capacitance retention of 90 %. The designed work elaborates on new guidelines for novel electrode material and explores the possibility of achieving the wide potential windows that can be utilized for practical energy storage applications.