Conductivity modification of gum acacia-based gel electrolytes

Abstract

Gum acacia (GA) is a natural gum with a high molecular weight; it is a polysaccharide material that is acidic in nature and the least viscous among hydrocolloids. The ion-conducting behavior of water-dissolvable GA-based gel electrolytes has been studied with salt (ammonium chloride (NH 4 Cl)) concentration, GA content and temperature enhancement. The conductivity of GA-based gel electrolytes without salt has been found to increase with the increase in GA content at low concentrations and reaches a maximum value of 4·99 × 10 −3 S/cm at 40 wt.% of GA and then shows a small decrease at higher concentrations of GA. GA-based gel electrolytes show ionic conductivity decrements and indicate negative activation energy with increase in temperature, which contradicts the theoretical explanation – that is, σ = σ o exp(−E a /K b T). An ionic conductivity on the order of 10 −1 S/cm has been observed for varying weights percentages of GA-based gel electrolytes containing 5 M ammonium chloride and does not show much change with temperature enhancement from 10 to 70°C, which makes it suitable for their use in fuel cells and other device applications.