High pressure anode operation of direct methanol fuel cells for carbon dioxide management

Experiments with independent pressurization of the direct methanol fuel cell anode and cathode allow for the observation of DMFC operation with carbon dioxide gas formation suppressed. Results indicate that the limiting current density is strongly related to the applied pressure, and, therefore, to the presence of CO2 in the liquid phase. An additional experiment where CO2 is allowed to accumulate in recycled anode fuel solution over a period of time and is then stripped from solution using nitrogen gas indicates that the presence of CO2 in anode fuel solution at any pressure contributes to significant decreases in power and current density. Because CO2 bubbles are ubiquitous in direct methanol fuel cells, this finding is key to the optimization of these systems.

► High pressure operation of DMFC improves maximum power density.
► High pressure operation of DMFC reduces limiting current density.
► Vacuum operation of DMFC enhances performance.
► Nitrogen stripping of CO2 from recycled anode fuel supply restores peak power density.