Coaxial electro-spun stretchable nanofiber electrode at wide electrochemical voltage

Flexible supercapacitors have important implications in the field of smart clothing and wearables due to the ultra-fast charging/discharging rate, long cycle life, environmental friendliness and sustainability. However, a simple method is lacking to synthesize wearable electrodes with both wide electrochemical voltage and high capacitance performance in one step. A coaxial electrospinning method is applied herein for preparation of selfsupported nanofiber electrode with polycaprolactone (PCL) as the core and Na-MnO2 as the sheath combined with impregnation of acid-modified carbon nanotubes (CNTs). Na-MnO2 prepared by hydrothermal method provides extra pseudo-capacitance and wide working window, polycaprolactone (PCL) and acid-modified CNTs further guarantee the stretchability and electrical conductivity. The stretchable symmetric supercapacitors based on the nanofiber electrodes with elongation at break of 62.39 % are further assembled with a capacitance of 0.655 mF/cm(2) at 100 mV/s and excellent tensile properties at the wide working voltage of 0-1.2 V. The stretchability and wide voltage of the devices constructed herein only by one-step core-shell spinning demon-strate the great potential of the doped MnO2-based nanofiber for applications in wearable energy storage field.