High-Performance Biomechanical Energy Harvester Enabled by Switching Interfacial Adhesion via Hydrogen Bonding and Phase Separation

Dramatic advances in wearable electronics have triggered tremendous demands for wearable power sources. To mitigate the impact of CO2 emission on the environment caused by energy consumption, biomechanical energy harvesting for self-powered wearable electronics offers a promising solution. The output power of devices largely relies on the surface charge density, where adhesion interfaces generate a higher amount than nonadhesion counterparts, yet unfavorable for wearable devices due to the large detachment force required. Thus, sustaining high surface charge density in an adhesion-free interface represents a major challenge. Herein, by leveraging intermolecular interactions and solvent evaporation induced phase separation, a nonadhesion interface is successfully realized, minimizing the interfacial adhesion from 20 to 0 kPa. Importantly, benefiting from the induced nano/microscale topography upon phase separation, comparable surface charges are generated at the interface. Consequently, a high-performance flexible biomechanical energy harvester featuring a record high peak power density of 20.5 W m^-2 Hz^-1 at low matching impedance of 1 MΩ is achieved under a low biomechanical input force of 5 N. The device can power small electronics by harvesting regular or intermittent biomechanical energy and illuminate light-emitting diodes wired/wirelessly. This work provides a facile strategy for interfacial engineering toward efficient energy harvesting.