Tannic Acid-Decorated Spongy Graphene for Flexible and High Performance Supercapacitors

A simple method was developed to prepare tannic acid-decorated spongy graphene hydrogel (TAGH) as interconnected, three-dimensional (3D) porous network supercapacitor electrode materials. Tannic acid (TA) not only can be fully competent in reducing graphene oxide and stabilizing reduced graphene oxide, but also can prevent graphene sheets from agglomerating by suppressing the pi-pi. stacking interactions. Such 3D porous TAGH electrodes with low charge transfer resistance of 0.4 Omega.cm(2) displayed a maximum specific capacitance of 533 F/g at 0.5 A/g. The assembled TAGH supercapacitor showed a good cycling stability (84.6% capacitance retention after 8000 charging/discharging cycles) and mechanical flexibility (93.4% capacitance retention after 500 folding/unfolding cycles). Remarkably, the flexible device can achieve superior energy density of 37.0 Wh/kg and higher power density of 4476.7 W/kg. These results demonstrate a great potential for application of 3D TAGH electrodes in flexible, high performance wearable electronics and energy storage devices. (C) 2018 The Electrochemical Society.