Conductive PEDOT:PSS/cellulose nanofibril paper electrodes for flexible supercapacitors with superior areal capacitance and cycling stability

PEDOT:PSS has been widely used as the electrode materials for supercapacitors. However, processing PEDOT:PSS bulk films with good flexibility and mechanical stability is still challenging. The present study is aimed at providing a facile and low-cost strategy for the preparation of mechanically strong and conductive PEDOT:PSS based bulk films by using Cellulose nanofibrils (CNF) as building blocks. PEDOT:PSS/CNF suspension was firstly prepared via a simple in situ polymerization process. Afterwards, flexible and conductive PEDOT:PSS/CNF nanopaper (PEDOT:PSS/CNP) were prepared from the PEDOT:PSS/CNF suspension by vacuum filtration and Dimethyl sulfoxide (DMSO) post-treatment. Results showed that the optimized PEDOT:PSS/CNP exhibited excellent flexibility, high tensile strength (72 MPa), and high electrical conductivity (66.67 S/cm). Finally, a symmetric supercapacitor was assembled using the PEDOT:PSS/CNP as electrodes. The assembled supercapacitor could deliver the maximum areal specific capacitance of 854.4 mF cm−2 (corresponding to 122.1F cm−3) at 5 mV/s and offer the highest areal energy density of 30.86 μWh cm−2 (corresponding to 4.41 mWh cm−3), which are among the highest values reported for PEDOT:PSS based supercapacitors. More importantly, the assembled supercapacitor showed remarkable cycling stability with the capacitance retention of 95.8% after 10,000 charge/discharge cycles. Considering the good mechanical properties and excellent electrochemical performance, the PEDOT:PSS/CNP could be a promising electrode material for flexible supercapacitors.