Recent Advances in Supercapacitor Materials and Devices (2020–2025): Comprehensive Analysis of Electrode Engineering, Electrolyte Design, and Device Performance

Supercapacitors have emerged as important electrochemical energy-storage technologies owing to their high power density, rapid charge-discharge capability, and long operational life.During 2020-2025, research in this field increasingly moved beyond isolated materials optimization toward integrated engineering of electrode chemistry, electrode architecture, electrolyte composition, and full-device configuration.This review critically examines recent advances in carbon-based electrodes, (TMS), metal oxides and hydroxides, metal-organic framework (MOF)-derived materials, chalcogenides, and multicomponent composite architectures.Particular emphasis is placed on TMS and MOF-derived electrodes because of their tunable redox chemistry, structural versatility, and potential for high-energy asymmetric and hybrid supercapacitors.Recent developments in aqueous, ionic-liquid, gel, and solid/quasi-solid electrolytes are discussed with respect to voltage-window expansion, ionic transport, safety, and temperature tolerance.The review further examines symmetric, asymmetric, and hybrid device architectures and critically evaluates commonly reported electrochemical metrics, incl uding capacitance, energy density, power density, and cycling stability.Special attention is given to inconsistencies arising from three-electrode measurements, mass normalization, electrode balancing, and insufficient reporting of practical device parameters.Finally, the review identifies major barriers associated with scalable manufacturing, structural degradation, electrolyte-electrode compatibility, standardization, and practical mass loading, and proposes research directions based on defect and interface engineering, advanced electrolytes, scalable electrode fabrication, data-driven materials discovery, and realistic device-level evaluation.