Fiber-shaped Supercapacitor and Electrocatalyst Containing of Multiple Carbon Nanotube Yarns and One Platinum Wire

Light weight and flexible fiber-shaped supercapacitors (FSSCs) that are considered to be ideal energy storage devices for powering wearable electronics. A flexible, high energy density all-solid-state Pt/n-CNT@PANI FSSCs was fabricated by using a simple method. The electrode was formed by twisting a number of CNT yarns (n) with one platinum filament as current collector, upon which PANI nanowires were deposited in-situ to form the final Pt/n-CNT@PANI FSSCs. The electrode structure with n = 5 fabricated at a twist level of 1000 T/m showed the best electrochemical performance. The optimum flexible Pt/5-CNT@PANI FSSC exhibited a specific capacitance of 217.7 F/g at the current density of 0.2 A/g, indicating a 7-fold increase in specific capacitance than the initial Pt/1-CNT@PANI with one CNT yarn (n = 1) of about 29.9 F/g. The Pt/5-CNT@PANI FSSC showed an energy density of 30.22 Wh/kg accompanied by a power density of 91.88 W/kg. The Pt/5-CNT@PANI exhibits remarkable electrocatalytic activity for hydrogen evolution reaction (HER) with a low onset overpotential of −188 mV and low Tafel slope of 84.99 mV/dec. The Pt/5-CNT@PANI yarns can be used as not only FSSC with excellent cycle stability and flexibility and but also an active and stable electrocatalyst for HER in alkaline electrolytes.