Electrochemical behavior of nickel–polyaniline electrode in 1 M LiClO4–propylene carbonate electrolyte

Abstract

Doping of emeraldine-base (EB) with lithium salts involves the addition of lithium cations to nitrogen in imine groups and intercalation of counter ions i.e., proceeds similarly to doping with protonic acids. The results of studies show that doping of polyaniline (PANI) with a lithium salt proceeds relatively difficultly as compared with protonic doping. For a polyaniline electrode, to attain faster the stationary mode by repeated cycling (“electrode training”) in an organic lithium electrolyte and to reach the higher capacitance, the method of preliminary lithiation of the NiO surface layer on the nickel substrate with Li⁺ cations through the EB film is proposed. The studies show that preliminary cycling of the Ni/PANI electrode (7 cycles at 10 mV s^–1) in the region of negative potentials (from 0 to–2.99 V vs. Ag/AgCl) leads to substantial increase in the capacitance characteristics of the PANI film in the region of its intrinsic redox activity from–0.4 to +1.1 V at high charge–discharge currents (2–5 A/g).