Large-Scale, Lightweight, and Robust Nanocomposites Based on Ruthenium-Decorated Carbon Nanosheets for Deformable Electrochemical Capacitors.

Despite the increase in demand for deformable electrochemical capacitors as a power source for wearable electronics, significant obstacles remain in developing these capacitors, including their manufacturing complexity and insufficient deformability. With recognition of these challenges, a facile strategy is proposed to fabricate large-scale, lightweight, and mechanically robust composite electrodes composed of ruthenium nanoparticles embedded in freestanding carbon nanotube (CNT)-based nanosheets (Ru@a-CNTs). Surface-modified CNT sheets with hierarchical porous structures can behave as an ideal platform to accommodate a large number of uniformly distributed Ru nanoparticles (Ru/CNT weight ratio of 5:1) while improving compatibility with aqueous electrolytes. Accordingly, Ru@a-CNTs offer a large electrochemically active area, showing a high specific capacitance (∼253.3 F g) and stability for over 2000 cycles. More importantly, the exceptional performance and mechanical durability of quasi-solid-state capacitors assembled with Ru@a-CNTs and a PVA-HPO hydrogel electrolyte are successfully demonstrated in that 94% of the initial capacitance is retained after 100 000 cycles of bending deformation and a commercial smartwatch is charged by multiple cells. The feasible large-scale production and potential applicability shown in this study provide a simple and highly effective design strategy for a wide range of energy storage applications from small- to large-scale wearable electronics.