Li 3+ ion irradiation effects on ionic conduction in P(VDF–HFP)–(PC + DEC)–LiClO 4 gel polymer electrolyte system

Abstract

Swift heavy ion irradiation of P(VDF–HFP)–(PC + DEC)–LiClO 4 gel polymer electrolyte system with 48 MeV Li 3+ 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 × 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.