Ion transport property of hot-press cast Mg²⁺-ion conducting nano-composite polymer electrolyte membranes: Study of effect of active/passive filler particle dispersal on conductivity

Ion transport properties of Mg²⁺-ion conducting nano composite polymer electrolyte (NCPE) films have been investigated. NCPE membranes were cast by a completely dry/solution free hot-press technique. Solid Polymer Electrolyte (SPE) composition: (85PEO: 15Mg(ClO₄)₂), identified as the highest conducting film in a separate study with room temperature conductivity σ ~ 2.27x10^-6 S/cm, has been used as Ist-phase host matrix and different active (micro/nano-sized MgO) and passive (nano-sized SiO₂ and TiO₂) filler particles as IInd-phase dispersoid. Effect of fillers of different nature on ionic conductivity has been studied. As a consequence of dispersal of filler particles in fractional amount, conductivity (σ) enhancement of approximately one order of magnitude could be achieved at room temperature along with substantial improvement in the mechanical integrity of the film. The total ionic transference number (t_ion) and the cationic (Mg²⁺) transference number (t₊) have been determined using dc polarization and a combined ac/dc IS techniques, respectively. Active filler particles resulted in the considerable increase in t₊ of NCPE film. The activation energy (E_a) has also been computed from temperature dependent conductivity plot. (author)