Effect of Plasticizers on Methyl Cellulose-Based Alkaline Solid Polymer Electrolytes

A preliminary investigation of biopolymer electrolytes based on methyl cellulose (MC), potassium hydroxide (KOH), and various plasticizing additives are described in this presentation. The electrolyte films with the composition of KOH between 5 and 50 wt.% (with respect to MC), were prepared by the solution cast technique. The biopolymer was first dissolved in distilled water with controlled amount of the KOH. The homogenous solutions obtained were evaporated in vacuum oven at constant temperature (40 °C) to form thin films. The room temperature ionic conductivity of the solvent free electrolytes films were characterized using impedance spectroscopy technique. In general, the unplasticized KOH based electrolytes were found to show moderate ionic conductivity up to 5.64×10^-6 S/cm. Upon the addition of plasticizers PC and EC the conductivity rises to 6.70×10^×6 and up to 3.58×10^-3 respectively. However, the addition of propylene carbonate (PC) and ethylene carbonate (EC) as a plasticizing additive lowered the mechanical stability. To control mechanical stability, the addition of such plasticizers is limited the suitability use of the electrolytes.