In this work, we electrochemically deposited self-doped polyanilines (SPANI) on the surface of carbon-nanoparticle (CNP) film, enhancing the superficial faradic reactions in supercapacitors and thus improving their performance. SPANI was electrodeposited on the CNP-film employing electropolymerization of aniline (AN) and o-aminobenzene sulfonic acid (SAN) comonomers in solution. Here, SAN acts in dual roles of a self-doped monomer while it also provides an acidic environment which is suitable for electropolymerization. The performance of SPANI−CNP-based supercapacitors significantly depends upon the mole ratio of AN/SAN. Supercapacitor performance was investigated by using cyclic voltammetry (CV), galvanostatic charge and discharge (GCD), and electrochemical impedance spectroscopy (EIS). The optimal performance of SPANI−CNP-based supercapacitor exists at AN/SAN ratio of 1.0, having the specific capacitance of 273.3 Fg⁻¹ at the charging current density of 0.5 Ag⁻¹.

A photopolymerization method is used to prepare a mixture of polymer ionic liquid (PIL) and ionic liquid (IL). This mixture is used as a solid-state electrolyte in carbon nanoparticle (CNP)-based symmetric supercapacitors. The solid electrolyte is a binary mixture of a PIL and its corresponding IL. The PIL matrix is a cross-linked polyelectrolyte with an imidazole salt cation coupled with two anions of Br⁻ in PIL-M-(Br) and TFSI⁻ in PIL-M-(TFSI), respectively. The corresponding ionic liquids have imidazolium salt cation coupled with two anions of Br⁻ and TFSI⁻, respectively. This study investigates the electrochemical characteristics of PILs and their corresponding IL mixtures used as a solid electrolyte in supercapacitors. Results show that a specific capacitance, maximum power density and energy density of 87 and 58 F·g⁻¹, 40 and 48 kW·kg⁻¹, and 107 and 59.9 Wh·kg⁻¹ were achieved in supercapacitors based on (PIL-M-(Br)) and (PIL-M-(TFSI)) solid electrolytes, respectively.

Without the addition of inorganic acids, 2,5-Diaminobenzenesulfonic acid (DABSA) molecules form an acid environment, and are then electrochemically copolymerized with AN monomers to generate a self-doped polyaniline (SPAN) film on mild steel substrates. These SPAN deposition films are employed to test the protection efficiency for mild steel in a corrosion environment of HCl and NaCl, respectively. Electrochemical impedance spectroscopy (EIS) and polarization were used to determine the charge transfer resistance (R_ct) and corrosion current (I_corr), respectively. The above two parameters R_ct and I_corr are combined to evaluate the protection efficiency of SPAN film on mild steel. Experimental results show that the SPAN thin film with the AN/DABSA ratio of 8.8 has the optimal corrosion resistance in 1 M HCl and 1 M NaCl aqueous solutions, respectively.