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4436860 
Journal Article 
Highly-branched cross-linked poly(ethylene oxide) with enhanced ionic conductivity 
Paranjape, N; Mandadapu, PC; Wu, G; Lin, H 
2017 
1 
Polymer
ISSN: 0032-3861 
111 
1-8 
WOS:000395223300001 
Polymers containing poly(ethylene oxide) (PEO) have been investigated for solid electrolytes for lithium ion batteries, which are preferred to be amorphous and have flexible polymer chains to achieve high Li ion conductivity. This paper reports ionic conductivity in a series of cross-linked PEOs prepared from poly(ethylene glycol) methyl ether acrylate (PEGMEA, monomer) and poly(ethylene glycol) diacrylate (PEGDA, cross-linker) via photopolymerization. The resulting copolymers contain short PEO side chains and thus high content of amorphous PEO. While the cross-linking enhances mechanical strength for solid electrolytes, the introduction of PEGMEA with methoxyl chain end groups decreases T-g and increases ionic conductivity. The use of acrylate groups for polymerization, instead of methacrylate groups, also yields low Tg and thus high conductivity. The effect of PEGMEA content, salt content, and temperature on the ionic conductivity was thoroughly investigated, and it was satisfactorily described using the Vogel-Fulcher-Tammann (VFT) equation. The effectiveness of PEO-based polymers used for solid electrolytes in advanced lithium batteries was also elucidated based on the VFT equation. (C) 2017 Elsevier Ltd. All rights reserved. 
Ionic conductivity; Branched poly(ethylene oxide); Glass transition temperature