Dramatic reduction of water crossover in direct methanol fuel cells by cathode humidification

As a key parameter in enabling the operation of high concentration methanol fuel cells, the water transport coefficient through the membrane must be reduced to between 0 and -1/6. We show that this coefficient can be lowered to -0.7 at 60°C and under common cathode flow conditions using fully humidified air. A previously developed membrane electrode assembly based on a Nafion 112 membrane was used. The present result gives rise to the possibility of achieving a water-neutral state for use of pure methanol, i.e., with the water crossover coefficient of -1/6, under temperatures much higher than 60°C and in active air-flowing direct methanol fuel cell systems with high power density.