Hydroelectric-driven asymmetric supercapacitor for closed-loop renewable energy integration

The expanding deployment of renewable energy systems requires electrochemical energy storage devices capable of stabilizing intermittent power fluctuations while simultaneously providing sustained energy output and rapid charge-discharge response. Although supercapacitors offer exceptional power density and long cycling stability, their relatively low energy density has limited widespread adoption in renewable energy-coupled applications. Addressing this challenge requires rational device engineering that simultaneously enhances charge-storage capacity and expands the operational voltage window, without compromising charge-transfer kinetics. Herein, we report a flexible solid-state asymmetric supercapacitor constructed using tungsten disulfide synthesized via a one-step hydrothermal route. The fabricated flexible device was systematically evaluated for electrochemical characteristics, rate capability, and mechanical resilience under flexible operating conditions. The optimized configuration achieves a stable 2 V operating voltage window, delivering a device capacitance of 169.8 F g − 1 , an energy density of 94.3 Wh kg − 1 , and a power density of 15,296 W kg − 1 , while maintaining robust long-term cycling stability of 10,000 cycles. Importantly, beyond conventional laboratory potentiostatic evaluation, we demonstrate direct hydroelectric-driven charging and scalable voltage integration up to 11 V through serial supercapacitor assembly. The device exhibits rapid charge acceptance and flow-dependent charging kinetics under hydrodynamic input, validating its capability to function as a renewable energy buffering unit. By bridging high-voltage solid-state architecture with renewable coupled validation, this work advances asymmetric supercapacitors from material level optimization toward deployable decentralized energy-storage systems.