A new class of lithium hybrid gel electrolyte systems

This report describes new materials prepared by using Li2PdCl4 [or (CH3)(2)SnCl2], Li3Fe(CN)(6) and glycerol, as precursors. The nearly instantaneous sol double right arrow gel process followed by complete dehydration under reduced pressure produced the [FexPdy(CN)(z)Cl-v(C3H8O3)Li-l] (I) and [FexSny(CH3)(2y)(CN)(z)Cl-v(C3H8O3)Li-l] (II) materials with the characteristics of a hybrid inorganic-organic gel (HGE), as confirmed by morphological studies. FIR, MIR, Raman laser, and UV-visible investigations together with detailed compositional data allowed us to propose a structural hypothesis and to describe the interactions between ions and glycerol in these materials. We concluded that the two HGEs consist of a hybrid backbone composed of a mixture of inorganic -organic clusters of Fe and Pd (or Sri) structural units with glycerol surrounded by nonbonded glycerol molecules. The materials I and II are thermally stable up to similar to115 and similar to125 degreesC, respectively. DSC investigations revealed their T-g at -74 and -76degreesC, respectively. Variable-temperature H-1 and Li-7 NMR line width, spin-lattice relaxation, and pulsed field gradient diffusion measurements were performed to investigate a possible correlation between glycerol mobility and lithium migration. Electrical spectroscopy measurements in the 10 mHz to 1 GHz range taken from -60 to +80 degreesC provided information regarding the systems' conductivity mechanism and structural relaxations. In addition, electrical spectra in the high-frequency region revealed the presence of an a relaxation event associated with glycerol molecules. This phenomenon suggests that the proposed HGEs exhibit the glycerol glass-forming behavior typical of supercooled materials. Finally, HGEs I and II exhibited room temperature conductivities of 5.0 x 10(-5) S-cm(-1) and 8.5 x 10(-5) S-cm-1, respectively, which classify these materials as good ion conductors.