Vapor-phase polymerization of fibrous PEDOT on carbon fibers film for fast pseudocapacitive energy storage

Poly(3,4-ethylenedioxythiophene) (PEDOT) has emerged as one of promising conductive polymers in energy storage devices. However, the conventional solution oxidative polymerization usually produces PEDOT with low conductivity and limited surface area. This work reports the preparation of highly conductive fibrous PEDOT by a vapor-phase polymerization initialized with Fe2O3 nanosheets that are uniformly electrochemically deposited on the N-doped carbon nanofibers (CNFs) film. The incorporation of highly conductive PEDOT nanofibers expands the film and simultaneously increase the film conductivity by 80 times (103 S cm−1). Accordingly, an areal capacitance of 1926 mF cm−2 at 5 mA cm−2 with a PEDOT mass loading of 8.68 mg cm−2 has been achieved. Importantly, the fast pseudocapacitive charge storage mechanism afford the CNF-PEDOT a high-rate capability which retains 68% capacitance in 5–50 mA cm−2. Especially, the CNF-PEDOT film electrode exhibits an outstanding stability with 87% capacitance retention after 10,000 consecutive charging and discharging cycles at 50 mA cm−2. A CNF-PEDOT-based supercapacitor delivers an energy density of 97 μWh cm−2 at power density of 0.45 mW cm−2, surpassing state-of-the-art PEDOT-based devices. This work will open a new avenue for preparing highly conductive PEDOT hybrid electrodes towards high-performance supercapacitors.