Nafion-Nafion/polyvinylidene fluoride-Nation laminated polymer membrane for direct methanol fuel cells

The laminated composite polymer electrolyte membrane is prepared as a sandwich structure, i.e., Nafion-Nafion/polyvinylene difluoride (PVdF)-Nafion. The conductivity of the laminated membrane is 1.1 x 10(-2) S cm(-1). The middle layer of PVdF/Nafion successfully blocks methanol cross-over. In tests in a direct methanol fuel cell (DMFC), all of the Nafion-Nafion/PVdF-Nafion membranes give higher power densities than with a Nafion membrane. The highest current density using a blend membrane with 20% PVdF at a constant cell voltage of 0.3 V is 217.64 mA cm(-2) at 110degreesC. It is noteworthy that the Nafion-Nafion/PVdF-Nafion laminated membrane sustains high performance at temperatures above 130degreesC, whereas the performance of a Nation membrane is drastically decreased. (C) 2004 Published by Elsevier B.V.