Highly Stretchable Supercapacitors Enabled by Interwoven CNTs Partially Embedded in PDMS

We present flexible and stretchable supercapacitors composed of interwoven carbon nanotubes (CNTs) embedded in polydimethylsiloxane (PDMS) substrates. CNTs are grown using atmospheric-pressure chemical vapor deposition (APCVD) on a Si/SiO2 substrate and then partially embedded into PDMS. This unique process permits a rapid and facile integration of the interwoven CNT–PDMS structure as a flexible and stretchable supercapacitor electrode with a high level of integrity under various strains. The electrochemical properties of the supercapacitors are measured in 30% KOH solution and with a poly(vinyl alcohol) (PVA)–KOH gel electrolyte (i.e., all-solid-state flexible supercapacitor). The measured capacitance of the supercapacitor is 0.6 mF/cm2 in 30% KOH solution and is 0.3 mF/cm2 with a PVA–KOH gel electrolyte at a scan rate of 100 mV/s, showing a consistent performance under stretching from 0% to 200% and bending/twisting angles from 0° to 180°. The stretching test is performed for 200 cycles from 0% to 100%, after which its capacitance is attenuated by 25%. The all-solid-state stretchable supercapacitors show a stable galvanostatic performance during and after 10 000 charge/discharge cycles with its capacitance maintained.