Unveiling Charge Storage Mechanisms in Transition Metal Chalcogenide Supercapacitors: Understanding through In-Situ/Operando Spectroscopy and DFT Studies

Abstract

Transition metal chalcogenides (TMCs) have emerged as promising electrode materials for supercapacitor (SC) application due to their high theoretical capacity and rich redox activity, but their real application remains limited by poor electrical conductivity, structural instability, and sluggish ion diffusion. Moreover, their charge-storage mechanisms remain unclear due to the complex interplay of surface redox reactions, ion intercalation, and structural changes. Recent advancements in various in-situ and operando spectroscopic techniques, such as Raman spectroscopy and X-ray absorption spectroscopy (XAS), have enabled real-time observation of the electronic, chemical, and structural changes during electrochemical processes. Moreover, density functional theory (DFT) modeling complements experimental findings by providing atomic-level insight into redox kinetics, and electronic structure changes that govern charge-storage behavior. This review discusses the recent progress in understanding the charge-storage behavior of TMC-based SC electrodes, highlighting how in-situ/operando spectroscopic techniques reveal real-time structural and chemical changes during electrochemical processes, while DFT approaches uncover the electronic and atomic-scale origins of charge storage mechanisms. Finally, the review outlines current challenges and future prospects, emphasizing the use of in-situ/operando studies and DFT analysis on actual devices, as well as the integration of these approaches for achieving precise structure-property relationships. Such combined strategies would guide the rational design and development of advanced TMC-based energy storage materials with enhanced performance and stability.