Stimuli-Triggered Diffusion Dynamics in Single-Junction Electrode for Enhanced Supercapacitor Performance: Insights into the Carrier Relaxation and Charge Transfer Kinetics

Study of external triggers add new chemistry to energy storage research by virtue of controlling diffusion and charge transfer dynamics. Herein, we have chosen a model system, Ag₂S-BiVO₄ (Ag₂S-BVO), for examining the diffusion dynamics upon light illumination using electrochemical and carrier relaxation studies. Favorable band alignments in the single-junction electrode lead to optimized carrier movement across the interfaces, developing a partial positive charge on the electrode, thereby enhancing the mass-transport of electrolyte ions toward the active electrode for efficient charge storage. Synergistic coupling across the heterojunction provides a high areal capacity of 338 mF cm^-2 at 0.5 mA cm^-2 under light illumination by facilitating the dominant diffusion characteristics within system. In addition, the Ag₂S-BVO-based asymmetric supercapacitor exhibits an areal energy density of 32 mWh cm^-2 @ 700 mW cm^-2 under illumination. This study provides a strategy to tune the capacitive and diffusion contributions for high-performance light-sensitive supercapacitor devices.