Li3+ ion irradiation effects on ionic conduction in P(VDF-HFP)-(PC+DEC)-LiClO4 gel polymer electrolyte system

Swift heavy ion irradiation of P(VDF-HFP)-(PC+DEC)-LiClO4 gel polymer electrolyte system with 48 MeV Li3+ ions having five different fluences was investigated with a view to increase the Li+ ion diffusivity in the electrolyte. Irradiation with swift heavy ion (SHI) shows enhancement of conductivity at lower fluences and decrease in conductivity at higher fluences with respect to unirradiated polymer electrolyte films. Maximum room temperature (303 K) ionic conductivity is found to be 2.2 x 10(-2) S/cm after irradiation with fluence of 10(11) ions/cm(2). This interesting result could be ascribed to the fluence-dependent change in porosity and to the fact that for a particular ion beam with a given energy higher fluence provides critical activation energy for cross-linking and crystallization to occur, which results in the decrease in ionic conductivity. The XRD results show decrease in the degree of crystallinity upon ion irradiation at low fluences (<= 10(11) ions/cm(2)) and increase in crystallinity at high fluences (> 10(11) ions/cm(2)). The scanning electron micrographs (SEM) exhibit increased porosity of the polymer electrolyte films after low fluence ion irradiation. (c) 2006 Elsevier B.V. All rights reserved.