Nafion–Nafion/polyvinylidene fluoride–Nafion 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 1.1×10−2 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 110 °C. It is noteworthy that the Nafion–Nafion/PVdF–Nafion laminated membrane sustains high performance at temperatures above 130 °C, whereas the performance of a Nafion membrane is drastically decreased.