Engineering Ultrathin Polyaniline in Micro/Mesoporous Carbon Supercapacitor Electrodes Using Oxidative Chemical Vapor Deposition

In this work, oxidative chemical vapor deposition (oCVD) is demonstrated to enable the integration of nanometer-thin polyaniline (PANI) that significantly improves charge storage capacity of supercapacitors utilizing carbide-derived carbon (CDC) with a bimodal (micro/mesoporous) pore size distribution. To our knowledge, this work is the first reported synthesis of PANI via oCVD. The oCVD process allows for the integration of PANI into pores as small as 1.7 nm, and resulting CDC/PANI electrodes have a gravimetric capacitance more than twice that of bare CDC (136 F g⁻¹ for 11 wt% of PANI in the CDC electrode versus 60 F g⁻¹ for bare Mo₂C-CDC at 10 mV s⁻¹). This yields a PANI-only gravimetric capacitance of ≈690 F g⁻¹, which is close to the theoretical value of 750 F g⁻¹. The coating preserves the native electrode surface area and pore size distribution, while improving capacitance due to the faradaic redox reactions of PANI. Even at high scan rates of over 100 mV s⁻¹, the added pseudocapacitance from PANI remains evident. The composite electrode exhibits good cyclability, decreasing to 90% of the initial value (≈100 F g⁻¹) after 10 000 cycles.