Ionic conduction studies in Li3+ ion irradiated P(VDF–HFP)–(PC + DEC)–LiCF3SO3 gel polymer electrolyte

Abstract

In an attempt to increase the Li ion diffusivity in gel polymer electrolytes, the effects of Li3+ ion irradiation in P(VDF–HFP)–(PC+DEC)–LiCF3SO3 electrolyte system, with five different fluences, is studied. Irradiation with swift heavy ions shows enhancement in conductivity at low fluences and decreased in conductivity at higher fluences with respect to pristine polymer electrolyte films. Maximum room temperature ionic conductivity after irradiation is found to be 2.6×10−3S/cm. This interesting result could be attributed to the fact that, higher fluence provides critical activation energy for cross-linking and crystallization to occur, which results in decrease in ionic conductivity. XRD results show decrease in the degree of crystallinity upon ion irradiation at low fluences (⩽1011ions/cm2) and increase in crystallinity at high fluences (>1011ions/cm2). In FTIR spectra the absorption band intensities around 3025cm−1 and 2985cm−1 decrease upon irradiation with a fluence of 5×1010ions/cm2 suggesting chain scission and increase upon irradiation with a fluence of 5×1012ions/cm2 indicating cross-linking. FTIR analyses corroborate the conductivity and XRD results.