Effect of TiO2 nano fillers on ionic conductivity enhancement in Mg(BH4)2:polyethylene oxide (PEO) polymer gel electrolyte

Temperature dependence of ionic conductivity of three different compositions of the Mg(BH4)(2):polyethylene oxide (PEO):propylene carbonate (PC) polymer gel electrolyte with Mg(BH4)(2):PEO molar ratios of 1:8, 1:10, and 1:12 was studied. The composition with Mg(BH4)(2):PEO = 1:10 exhibited the highest ionic conductivity of 7.60 x 10(-6) S cm(-1) at 30 degrees C. The effect of TiO2 nanofiller on ionic conductivity enhancement was studied for Mg(BH4)(2):PEO:PC:TiO2 polymer gel electrolyte by varying the TiO2 weight ratio from 0 to 12.5 wt.%. The highest ionic conductivity of 17.95 x 10(-6) S cm(-1) at 30 degrees C was exhibited by the electrolyte composition with 10 wt% of TiO2 nanofiller. The optimized electrolytes had a Mg++ cationic transference number of 0.22 for the filler free electrolyte and 0.30 for the TiO2 10wt% filler incorporated electrolyte. Both electrolytes had negligible electronic conductivity. A more than two-fold increase in the ionic conductivity and a 30% increase in Mg++ ion transference number can be attributed to the nanofiller effect caused by TiO2. This preliminary study shows the possibility of developing this PEO-based polymer gel electrolyte to be used in rechargeable Mg ion batteries.