Self-diffusion coefficients of lithium, anion, polymer, and solvent in polymer gel electrolytes measured using Li-7,F-19, and H-1 pulsed-gradient spin-echo NMR

Four series of solution and corresponding polymer gel electrolyte systems w ere studied. The systems were composed of a solvent (gamma-butyrolactone (G BL) or propylene carbonate (PC)), (three different concentrations of) a lit hium salt (LiBF4 or lithium bis(trifluromethanesulfonyl)-imide (LiTFSI, LiN (SO2CF3)(2))), and poly(ethylene glycol diacrylate) of molecular weight 400 0 (PEO), which was cross-linked to form the polymer gels. The self-diffusio n coefficients of the lithium, the anions, the solvents and the polymer wer e obtained independently using Li-7, F-19 and H-1 pulsed-gradient spin-echo NMR measurements. From the individual diffusion coefficients of each compo nent of the GBL-LiBF4, GBL-LITFSI, PC-LiBF4, and PC-LiTFSI solutions and th e corresponding polymer gel electrolytes, the solvation and the solvent-dep endent behaviour of the lithium and the anions are clearly shown. Especiall y in the gels, the lithium binding with the PEO matrix were found to be qui te different depending on whether the solvent was PC or GEL. (C) 2000 Elsev ier Science Ltd. All rights reserved..