Preparation and Properties of Poly(vinyl alcohol)/Poly(vinyl pyrrolidone) Composites for Solid Alkaline Electrolyte Membranes

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/KOH composite 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 ℃.These membranes are,therefore,promising solid alkaline electrolyte membranes for use in alkaline direct methanol fuel cells at elevated operating temperature.