Rational co-growth of molybdenum tungsten disulphide on Se-modified MWCNTs as cathode material for battery-supercapacitor hybrids

Abstract

A simple and rational strategy was employed to fabricate a highly three-dimensional (3D) network structure of WMo-S₂@Se-ACNTs as a suitable cathode for a battery-supercapacitor hybrid (BSH) via a hydrothermal process. A strong synergy between the transition metal ions during the co-deposition of tungsten-molybdenum disulfide (WMo-S₂) onto selenium-doped acid treated MWCNTs (Se-ACNTs) has been found to significantly enhance electrochemical activity, rate capability, and cycling stability. Consequently, the fabricated electrode exhibited outstanding mechanical and electrochemical properties, including low ohmic resistance and a high areal capacitance of 800F.g⁻¹ at 2.0 A.g⁻¹. Additionally, the WMo-S₂@Se-ACNTs showed 53 % pseudocapacitance and 47 % electric double-layer capacitance at 5.0 mV.s⁻¹. As a result, the pseudocapacitive property significantly enhances the rate performance. Furthermore, Quasi-solid-state Battery Supercapacitor Hybrid (QSS-BSH) fabricated by using WMo-S₂@Se-ACNTs as the cathode and reduced Graphene Oxide-Acid treated MWCNTs (rGO-ACNTs) as the anode and Quasi-solid-state Polyvinyl alcohol/Sulfuric acid (PVA/H₂SO₄) as the separator and electrolyte. The fabricated device demonstrated exceptional electrochemical performance, including a high operating voltage of 2.0 V, long-term cyclic stability (91 % capacitance retention after 6000 cycles), and high energy and power densities with a specific energy density of 134 Wh.kg⁻¹ and 380 Wh.kg⁻¹ at specific power densities of 1165 W.kg⁻¹ and 832 W.kg⁻¹, respectively.