A facile approach to improve the electrochemical properties of polyaniline-carbon nanotube composite electrodes for highly flexible solid-state supercapacitors

We seek to improve the electrochemical properties of supercapacitor via engineering the interface of electroactive material/current collector. A facile electrochemical method is put forward to fabricate expanded graphite (ExGP), and polyaniline-carbon nanotube (PANI-CNT) composite electrodes using ExGP as substrate are prepared by one-step co-electrodeposition. Compared with PANI-CNT/GP electrodes, PANI-CNT/ExGP electrodes show significantly improved electrochemical capacitive performances due to reduced constriction/spreading resistance. This effect is ascribed to the increased area of contact points at the interface of electroactive material/current collector for the latter. The PANI-CNT/ExGP electrodes deliver a specific capacitance of 826.7 F g−1, higher than previous reports based on PANI-CNT composites. A highly flexible solid-state supercapacitor is assembled using PANI-CNT/ExGP electrodes. The device shows high rate capability, superior energy/power characteristics (7.1 kW kg−1 at an energy density of 12.0 Wh kg−1), and good cycling stability. This study demonstrates that optimizing electroactive material/current collector interface can implement faster electron transport and represents an effective strategy to promote electrochemical capacitive properties of supercapacitors.