An NMR investigation of ionic structure and mobility in plasticized solid polymer electrolytes

Na-23 and F-19 nuclear magnetic resonance spectroscopy is used to investigate the effect of plasticizer addition on ionic structure and mobility in a urethane crosslinked polyether solid polymer electrolyte. The incorporation of dimethyl formamide and propylene carbonate plasticizers in a sodium triflate/polyether system results in an upheld chemical shift for the Na-23 resonance consistent with decreased anion-cation association and increased cation-plasticizer interactions. The F-19 resonances appears less susceptible to changes in chemical environment with only minor chemical shift changes recorded. Spin lattice relaxation measurements for the F-19 nucleus are also reported. Two minima are observed in the relaxation measurements consistent with both an inter and intramolecular relaxation mechanism.