Enhancement in supercapacitive performances of polyaniline nanofiber electrodes using surface-expanded graphite substrate

A facile surface-treated method is developed to fabricate surface-expanded graphite foil (SE-GF), which serves as substrate for the electrochemical growth of polyaniline (PANI), to enhance the supercapacitive performances of obtained PANI electrodes. We also compare the electrochemical properties of electro polymerized PANI with different dopants. Comparing with H2SO4 doped PANI electrodes, HClO4 doped PANI electrodes show enhanced electrochemical capacitive properties due to the formed loose morphology of nanofibers. More importantly, the supercapacitive performances of PANI nanofibers grown on SE-GF substrate are remarkably improved in comparison to those grown on GF substrate. This is caused by the optimal electron transfer pathways constructed at the interface of SE-GF substrate and PANI films. The resulting SE-GF/PANI electrodes exhibit superior electrochemical properties such as high specific capacitance (422.1 mF cm−2 at 0.5 mA cm−2), good rate performance, and remarkable cycling stability (94.1% of capacitance retention for 5000 cycles). Such characteristics offer great promise in high performance supercapacitor applications. This study demonstrates the importance of electron transfer pathways at the interface of substrate/current collector and electroactive material for electrochemical performances of electrodes.