Paper Electrodes Coated with Partially-Exfoliated Graphite and Polypyrrole for High-Performance Flexible Supercapacitors

Flexible paper electrodes for supercapacitors were prepared with partially-exfoliated graphite and polypyrrole as the active materials. Graphite was coated on paper with pencil drawing and then electrochemically exfoliated using the cyclic voltammetry (CV) technique to obtain the exfoliated graphite (EG)-coated paper (EG-paper). Polypyrrole (PPy) doped with beta-naphthalene sulfonate anions was deposited on EG-paper through in-situ polymerization, leading to the formation of PPy-EG-paper. The as-prepared PPy-EG-paper showed a high electrical conductivity of 10.0 S.cm(-1) and could be directly used as supercapacitor electrodes. The PPy-EG-paper electrodes gave a remarkably larger specific capacitance of 2148 F.g(-1) at a current density of 0.8 mA.cm(-2), compared to PPy-graphite-paper (848 F.g(-1)). The capacitance value of PPy-EG-paper could be preserved by 80.4% after 1000 charge/discharge cycles. In addition, the PPy-EG-paper electrodes demonstrated a good rate capability and a high energy density of 110.3 Wh.kg(-1) at a power density of 121.9 W.kg(-1). This work will pave the way for the discovery of efficient paper-based electrode materials.