The ion diffusion and conduction phenomena in origoethers and polyethers: CH{sub}3(OCH{sub}2CH{sub}2)OCH{sub}3, n=2～56

摘要

Polyethyleneoxides (PEG) are applicable to the solid polymer electrolyte due to their flexibility and high solubility for alkaline salts. We studied the electrolytes composed of smaller series of PEG molecules, so called "glyme family" like diglyme (DC), triglyme (TC), tetraglyme (TeG), pentaglyme (PG), and polyethyleneglycol dimethyl ether (PEGDM) with the molecular weights of 400, 1,000 and 2,500. The ionic conductivities of the electrolytes doped with LiN(SO{sub}2)CF{sub}3){sub}2 were measured. Also the self-diffusion coefficients were measured for the solvent, anion and lithium ion by the pulsed-field gradient spin-echo (PGSE) 1{sup left}H, 19{sup left}F, and 7{sup left}Li NMR, respectively. The spin-lattice relaxation times (T{sub}1) have been measured for investigation of the local polymer segmental and lithium hopping motions. The segmental motions continuously slow down as the molecular size of the solvents increases. The diffusion and ion conduction mechanisms are discussed and the lithium ion-solvent interaction schemes are shown to depend on the solvent size.