PREPARATION OF FUNCTIONALIZED SiO2/F-SF POSS HYBRID FILLERS AND THEIR APPLICATION IN GEL POLYMER ELECTROLYTES

Hybrid SiO2/POSS fillers were obtained using the method based on solvent evaporation. Octakis({1,1,2,2,3,3,4,4-octafluoropentyloxypropyl}dimethylsiloxy) octasilsesquioxane (F-SF FOSS) was used to modify the surface of silica, hydrated or prepared via emulsion method. The effectiveness of modification was evaluated by FT-IR spectroscopy and nuclear magnetic resonance (Si-29 and C-13 CF MAS NMR). The parameters of porous structure of the prepared hybrid fillers, such as surface area BET, mean pore diameter and pore volume were determined. The hybrid products were subjected to dispersive analysis (non-invasive backscattering method, NIBS) and morphological characterization (using transmission electron microscopy - TEM). The obtained hybrid systems were used as additives in gel polymer electrolytes, prepared by activation of dry composite membranes in a liquid solution of lithium salt. The electrolytes were subjected to electrochemical studies, including the measurements of specific conductivity by impedance spectroscopy in a wide range of temperatures and the determination of potential windows by the linear cyclic voltammetry. The addition of FOSS composites had a beneficial effect on the transport of lithium cations and the room temperature conductivity of gel electrolytes based on PVdF/HFP membranes was enhanced by an order of magnitude. The observed increase in gel conductivity was poorly correlated with the ability of liquid phase absorption. The anodic stability of gels only slightly increased upon the addition of FOSS to PVdF/HFP membranes. The fillers studied show promising properties in the context of future research and development studies on new solid electrolytes for lithium cells with increased safety.