Dynamic electrochemical properties of extremely stretchable electrochemical capacitor using reduced graphene oxide/single-wall carbon nanotubes composite

Stretchable reduced graphene oxide (rGO)/single-wall carbon nanotubes (SWNTs) composite electrodes were prepared using a spray coating technique onto gold-coated latex substrates. Poly(vinyl alcohol) (PVA)/phosphoric acid (H3PO4) was used as a stretchable electrolyte in order to assemble a symmetrical electrochemical capacitor (EC). Cyclic voltammetry (CV) indicated a typical double layer capacitance, even after a number of stretching cycles. Electrochemical impedance spectroscopy (EIS) showed a well-defined capacitive responsewith lowinternal resistance after repetitive stretching to 100% strain.Galvanostatic charge/discharge measurements with up to 100 stretch cycles yielded symmetrical charge/discharge curves indicating reversibility and facile kinetics. The highest capacitance of an unstrained latex EC was 61 F g^-1 (15.3 mF cm^-2), which decreased to 49 F g^-1 (12.3 mF cm^-2) and 42 F g^-1 (10.5 mF cm^-2) after 50 and 100 stretching cycles, respectively. The stretchable EC subjected to 100 stretching cycles retained approximately 67% of its initial capacitance value after 3,000 charge/discharge cycles.