Single lithium-ion conducting polymer electrolytes based on poly[(4-styrenesulfonyl)(trifluoromethanesulfonyl)imide] anions

New single lithium-ion conducting polymer electrolytes are prepared by a copolymerization of the two monomers, lithium (4-styrenesulfonyl)(trifluoromethanesulfonyl)imide (LiSTFSI) and methoxy-polyethylene glycol acrylate (MPEGA, CH2=HCO2-(CH2CH2O)(n)-CH3, n=8) in various monomer ratios. The structures and compositions of the prepared lithium poly[(4-styrenesulfonyl) (trifluoromethanesulfonyl)imide-co-methoxy-polyethylene glycol acrylate] (Li[PSTFSI-co-MPEGA]) copolymers are characterized by H-1 and F-19 NMR, and gel permeation chromatography (GPC). For comparison, the corresponding blended polymer electrolytes comprising lithium poly[(4-styrenesulfonyl) (trifluoromethanesulfonyl)imide] (LiPSTFSI) and poly(ethylene oxide) (PEO) are also prepared and characterized. The fundamental properties of these two types of lithium-ion conducting polymer electrolytes are comparatively studied, in terms of phase transitions, thermal stability, XRD, ionic conductivities, lithium-ion transference numbers (t(Li)(+)), and electrochemical stabilities. Both types of the polymer electrolytes are thermally stable up to 300 degrees C. While both types of polymer electrolytes exhibit single lithium-ion conducting behavior with t(Li)(+)>0.9, the solid-state ionic conductivities of the Li[PSTFSI-co-MPEGA] copolymer electrolytes are all higher by 1-3 orders in magnitude than those of the blended ones, irrespective of the concentration of lithium ions. The highest ionic conductivities for the copolymer electrolytes are 7.6 x 10(-6) S cm(-1) at 25 degrees C and reach 10(-4) S cm(-1) at 60 degrees C, which are obtained at the ethylene oxide (EO) unit/Li+ ratio of 20.5. (C) 2013 Elsevier Ltd. All rights reserved.