Time-Resolved Electrochemical Kinetics and Pseudocapacitive Charge Storage in Fe-MOF@CoSn-Based Asymmetric Hybrid Supercapacitors

Metal–organic frameworks (MOFs) have attracted significant interest as electrode materials for energy storage systems owing to their tunable structures, large surface areas, and adjustable physicochemical properties. In this study, MIL-100(Fe) was successfully grown on CoSn(OH)6 (MOF@CTH), and its electrochemical performance was systematically evaluated for asymmetric hybrid supercapacitors (AHS). The charge storage mechanism was elucidated through Dunn analysis, revealing a significant increase in the distinct capacitive contributions for MOF@CTH2. Additionally, the distribution of relaxation times analysis provided detailed insight into electrochemical kinetics, highlighting a capacitive Faradaic and noncapacitive Faradaic charge transfer process occurring within the relaxation timescale of 0.1–1 s for MOF@CTH2. The MOF@CTH2 electrode attained an outstanding specific capacitance of 1124.6 F/g, corresponding to a specific charge of 562.3 C/g. The hybrid two-electrode system constructed with MOF@CTH2 and reduced graphene oxide as the positive and negative electrode, respectively, delivered an energy density of 36.21 Wh/kg and a power density of 749.98 W/kg. This work advances our understanding of time-resolved electrochemical processes in MOF-based systems and highlights their potential in high-performance AHS applications.