Highly flexible and transparent dielectric elastomer actuators using silver nanowire and carbon nanotube hybrid electrodes.

We demonstrate a dielectric elastomer actuator (DEA) with a high areal strain value of 146% using hybrid electrodes of silver nanowires (AgNWs) and single-walled carbon nanotubes (SWCNTs). The addition of a very small amount of SWCNTs (∼35 ng mm-2) to a highly resistive AgNW network resulted in a remarkable reduction of the electrode sheet resistance by three orders, increasing the breakdown field by 183% and maximum strain, while maintaining the reduction of optical transmittance within 11%. The DEA based on our transparent and stretchable hybrid electrodes can be easily fabricated by a simple vacuum filtration and transfer process of the electrode film on a pre-strained dielectric elastomer membrane. We expect that our approach will be useful in the future for fabricating stretchable and transparent electrodes in various soft electronic devices.

All-solid-state flexible supercapacitor based on nanotube-reinforced polypyrrole hollowed structures.

Supercapacitors are strong future candidates for energy storage devices owing to their high power density, fast charge-discharge rate, and long cycle stability. Here, a flexible supercapacitor with a large specific capacitance of 443 F g-1 at a scan rate of 2 mV s-1 is demonstrated using nanotube-reinforced polypyrrole nanowires with hollowed cavities grown vertically on a nanotube/graphene based film. Using these electrodes, we obtain improved capacitance, rate capability, and cycle stability for over 3000 cycles. The assembled all-solid-state supercapacitor exhibits excellent mechanical flexibility, with the capacity to endure a 180° bending angle along with a maximum specific and volumetric energy density of 7 W h kg-1 (8.2 mW h cm-3) at a power density of 75 W kg-1 (0.087 W cm-3), and it showed an energy density of 4.13 W h kg-1 (4.82 mW h cm-3) even at a high power density of 3.8 kW kg-1 (4.4 W cm-3). Also, it demonstrates a high cycling stability of 94.3% after 10 000 charge/discharge cycles at a current density of 10 A g-1. Finally, a foldable all-solid-state supercapacitor is demonstrated, which confirms the applicability of the reported supercapacitor for use in energy storage devices for future portable, foldable, or wearable electronics.