Effects of 160 MeV Ni12+ ion irradiation on HCl doped polyaniline electrode

Abstract

Conducting polymers are suitable as electrode materials for high performance supercapacitors because of their high specific capacitance and high dc conductivity in the charged state. Ion beam (energy >1 MeV) irradiation of materials is a novel technique to modify their properties. Polyaniline conducting polymer thin films doped with HCl are synthesized electrochemically on indium tin oxide coated glass substrates and are irradiated with 160 MeV Ni12+ ions at different fluences, namely, 5 × 1010, 5 × 1011 and 3 × 1012 ions cm−2. The dc conductivity measurements of the irradiated films showed up to 70% increase in conductivity, which may be due to the increase of carrier concentration in the polymer film as observed in UV-Vis spectroscopy and other effects like the cross linking of polymer chains, bond breaking and creation of defects sites. An x-ray diffractogram study shows that the degree of crystallinity of polyaniline increases upon swift heavy ion (SHI) irradiation with the increase in ion fluence. The capacitance of the irradiated films is lowered but that of the supercapacitors with irradiated films showed enhanced electrochemical stability compared with the devices with unirradiated films while characterized for a cycle life up to 10 000 cycles. This effect could possibly be ascribed to the stabilization of volatile surface groups upon SHI irradiation.