Modified transition metal chalcogenides for high performance supercapacitors: Current trends and emerging opportunities

The quest for high-performance supercapacitive materials which can deliver high power density like conventional capacitors and high energy density like conventional batteries has never been descended among the research community. Among various electrode materials, transition metal chalcogenides have attracted significant attention owing to their intriguing electrochemical characteristics such as rich redox chemistry, multiple valence states, higher electronic conductivity as compared to their oxide counterparts, fast ion diffusion kinetics, and morphological diversity; however, they suffer from poor rate performance, cyclability, surface area, and agglomeration issues. To levitate their electrochemical performance, researchers have unveiled various modification strategies including composite fabrication with various carbon allotropes and conductive polymers, forming heterostructures with different metal compounds, fabricating mixed metal chalcogenides, and by doping heteroatoms. Nevertheless, a more profound correlation between the type of modification and resultant electrochemical performance is still coveted. This review briefly discusses the challenges associated with the supercapacitor application of transition metal chalcogenides, and the importance of the modification approach, followed by a comprehensive discussion on different modification strategies and how these strategies have helped in elevating their electrochemical performance. Moreover, this review also outlines the associated existing challenges and future opportunities in the field.