Fabrication and electrochemical evaluation of polyhedral PANI-coated Co₃O₄ electrode for supercapacitor application

In this work, conducting polymer modification on metal oxide surfaces was targeted to improve the composite conductivity and stability for electrochemical energy storage applications. Polyhedral cobalt oxide (Co₃O₄) was prepared using a molten salt combustion method and coated with polyaniline (PANI). The composite (PANI-CoM) was characterized using XRD, TGA, FTIR, FESEM, TEM, and BET. From cyclic voltammetry analysis in 6 M KOH, PANI-CoM shows a high C_S (985 F/g) compared to bare Co₃O₄ (278 F/g), indicating that PANI coating has improved pseudocapacitive charge storability of the electrode. The electrolyte diffusion on the internal active surfaces has increased from 11% to 31%, contributed by the reduction of internal resistance by 29%. Activated carbon and ordered mesoporous carbon (OMC) were used to manufacture two sets of asymmetrical supercapacitor devices, and PANI-CoM/OMC functioned the best performance with an E_D of 22 Wh/kg at a P_D of 400 W/kg.