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Keywords:

Science & Technology, Physical Sciences, Chemistry, Inorganic & Nuclear, Chemistry, Polymers, Ionic liquids, Hybrid membranes, Hydrogen bonds, Lithium batteries, POLY(ACRYLIC ACID), GEL ELECTROLYTES, ALCOHOL), TEMPERATURE, IMIDAZOLIUM, PERFORMANCE, MEMBRANES, 0302 Inorganic Chemistry, 0399 Other Chemical Sciences, Inorganic & Nuclear Chemistry, 3402 Inorganic chemistry

Abstract:

Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Polymer blends of poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA) were prepared with different molar ratios by a solvent-casting technique. The XRD patterns of the blends show that the degree of crystallinity of the PVA membranes decreases with the addition of PAA owing to the formation of interpenetrating polymer chains. The vibrational spectra of the blend membranes reveal the formation of strong hydrogen bonding between PVA and PAA. Dynamic mechanical analysis (DMA) reveals that the storage modulus of a 25 mol-% PAA sample is comparable to that of pure PVA and, therefore, confirms the mechanical stability of the blend membranes. Significant changes in the peak areas and chemical shifts of the PVA hydroxyl signal (δ = 4-5 ppm) in the 1H NMR spectra of the blend membranes confirm the strong hydrogen bonding between the OH groups of PVA and PAA. The ionic liquid (IL) 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR14TFSI) with 0.2 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) was added to the polymer blend to prepare flexible, nonvolatile hybrid polymer electrolytes for lithium-ion batteries. A maximum ionic conductivity of 1 mScm-1 is observed at 90 C for the membrane with 70 mol-% IL. Mechanically stable polymer membranes for lithium-ion batteries consist of 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl) imide (PYR14TFSI) doped with 0.2 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI).