Water Crossover Experiments in an Open-Cathode Direct Methanol Fuel Cell

A direct methanol fuel cell (DMFC) that does not require an external water feed or a powered water-recovery system has potential for wide application in portable electronic devices. This paper provides experimental data for the water recovery rate in a novel DMFC design featuring a hydrophobic cathode gas-diffusion layer that allows for passive water recovery. Water and methanol crossover rates were experimentally characterized by measuring the water vapor and carbon dioxide concentration at the cathode exit with an infrared sensor. The result showed that the mass-transport parameter of water vapor, increases linearly with increasing cell temperature and remains invariant with respect to the cell current density. Water neutrality of the DMFC stack was achieved while the cell operated close to 50 °C and 150 mA/cm² with a 1M methanol solution. A comprehensive empirical equation based on the experimental results is presented, along with system-level insights into the controllability of water management in designing an open cathode DMFC system.