Preparation and properties of Poly(vinyl alcohol)/Poly(vinyl pyrrolidone) composites for solid alkaline electrolytemembranes

Abstract

Solid alkaline electrolyte membranes were prepared using poly(vinyl alcohol)/poly(vinyl pyrrolidone) (PVA/PVP) by KOH doping. The composition, microstructure, thermal stability, ionic conducitvity and methanol uptake of the composite membranes were investigated in detail. The wholly transparent, homogeneous and compact PVA/PVP/KOHcomposite membranes were obtained when m(PVA):m(PVP)=1:0.5 in a mass ratio and no obvious phase seperation was observed. The ionic conductivity and thermal stability of the PVA/PVP membranes increased greatly with increasing the content of PVP. A high ionic conductivity of 2.01×10-3 S·cm-1 was obtained when a mass ratio of m(PVA);m(PVP)=1:1 was used. In additon, the methanol uptake of the PVA/PVP/KOH membranes showed almost no change after conditioning at elevated temperatures and it was 4 times lower than that of the Nafion 115 membrane after conditioning at 100°C. These membranes are, therefore, promising solid alkaline electrolyte membranes for use in alkaline direct methanol fuel cells at elevated operating temperature. © Editorial office of Acta Physico-Chimica Sinica.