Highly Stretchable Supercapacitors via Crumpled Vertically Aligned Carbon Nanotube Forests

Stretchable supercapacitors have received increasing attention due to their broad applications in developing self-powered stretchable electronics for wearable electronics, epidermal and implantable electronics, and biomedical devices that are capable of sustaining large deformations and conforming to complicated surfaces. In this work, a new type of highly stretchable and reliable supercapacitor is developed based on crumpled vertically aligned carbon nanotube (CNT) forests transferred onto an elastomer substrate with the assistance of a thermal annealing process in atmosphere environment. The crumpled CNT-forest electrodes demonstrated good electrochemical performance and stability under either uniaxial (300%) or biaxial strains (300% x 300%) for thousands of stretching-relaxing cycles. The resulting supercapacitors can sustain a stretchability of 800% and possess a specific capacitance of 5 mF cm(-2) at the scan rate of 50 mV s(-1). Furthermore, the crumpled CNT-forest electrodes can be easily decorated with impregnated metal oxide nanoparticles to improve the specific capacitance and energy density of the supercapacitors. The approach developed in this work offers an alternative strategy for developing novel stretchable energy devices with vertically aligned nanotubes or nanowires for advanced applications in stretchable, flexible, and wearable electronic systems.