Fabrication of anion-exchange composite membranes for alkaline direct methanol fuel cells

The quaternized poly(vinyl alcohol)/3-(trimethyl ammonium) propyl-functionalized silica (designated as QPVA/Q-SiO2) composite polymer membrane is prepared by a solution casting method. The Q-PVA is polyvinyl alcohol (PVA) derivatized with glycidytrimethyl ammonium chloride (GTMAC) and the Q-SiO2 is 3-(trimethyl ammonium) propyl-functionalized silica. The highest ionic conductivity of the QPVA/20 wt.%Q-SiO2 composite polymer electrolyte is σ = 2.37 mS cm−1 at ambient temperature. The alkaline direct methanol fuel cell (ADMFC) comprised of an anion-exchange QPVA/Q-SiO2 composite membrane is assembled and examined. The highest peak power density of the DMFC with 8 M KOH + 2 M CH3OH fuel is 35.13 mW cm−2 at 50 °C and 1 atm air. The peak power density is 0.27 mW cm−2 with a pure 2 M CH3OH fuel at 25 °C and 1 atm air.

► The quaternized poly(vinyl alcohol)/3-(trimethyl ammonium) propyl-functionalized silica (designated as QPVA/Q-SiO2) composite polymer membrane was applied on ADMFC.
► The highest ionic conductivity of the QPVA/20 wt.%Q-SiO2 composite polymer electrolyte in water is 2.37 mS cm−1 at ambient temperature.
► The addition KOH electrolyte in methanol fuel plays a vital role in improving the performance of alkaline direct methanol fuel cell (ADMFC).