Preparation and Characterization of Composite Polymer Electrolytes Based on UV-Curable Vinylic Ether-Containing Cyclotriphosphazene, LiClO4, and α-Al2O3

A new UV-curable vinylic ether-containing cosubstituted cyclotriphosphazene, N 3 P 3 (O(CH 2 CH 2 O) 2 CH 3 ) 3 (OCH 2 CH 2 OCH CH 2 ) 3, [V 3 M 3 ], was synthesized with high yield. This cosubstituted cyclotriphosphazene was characterized by FT-IR, ESI-MS, and 1 H, 13 C, and 31 P NMR spectroscopy. A series of free-standing films with thickness of about 200 μm of V 3 M 3 -based composite polymer electrolytes were then prepared by mixing V 3 M 3 with various amounts of LiClO 4 salt and α-Al 2 O 3 and cured by UV irradiation. The cation−oxygen interactions in the cured polymer electrolytes were investigated by FT-IR spectroscopy. The ionic conductivities of the cured polymeric membranes measured by ac impedance measurements showed that the best conductivity of the as-prepared solid polymer electrolyte film at room temperature was 3.5 × 10 -5 S/cm. The result of the cyclic voltammetry measurements revealed that the V 3 M 3 -based composite polymer electrolyte films were electrochemically stable up to about 4.2 V.