Infrared studies of polyacrylonitrile-based polymer electrolytes incorporated with lithium bis(trifluoromethane)sulfonimide and urea as deep eutectic solvent

摘要

In this work, urea is introduced into polyacrylonitrile (PAN)-based polymer electrolyte containing lithium bis(trifluoromethane)sulfonimide (LiTFSI) to form a deep eutectic solvent with urea and LiTFSI in the mole ratio of 1:3. The ambient ionic conductivity of the polymer electrolyte film is enhanced from 2.54 x 10(-4) S cm(-1) to 3.82 x 10(-3) S cm(-1) with the addition of urea. Infrared studies has revealed that urea interacts with the LiTFSI through coordination of Li+ ions onto the carbonyl (C=0) group of urea, and hydrogen bonding possibly to the O atoms in the SO2 groups of TFSI- ions. Hydrogen bondihg interactions of urea with DMF and PAN are also evident. The enhancement in conductivity is believed to be due to urea being involved in the dissociation of LiTFSI and its role as an additional ion conduction pathway through its carbonyl group. (C) 2016 Elsevier B.V. All rights reserved.