Fully passive degassing and fuel supply in direct methanol fuel cells

In this paper a micro direct methanol fuel cell (muDMFC) is presented, which is operated in a completely passive way, i.e. the cell does not require an external pump for fuel supply. The surface energy of deformed CO₂ bubbles, generated as a reaction product during DMFC operation, is employed to supply methanol to the anode. In contrast to a digital valve based approach presented earlier by Meng et. al. [1], a tapered channel is applied to achieve a pumping mechanism. This way the pump rates can be adapted to the requirements of a specific cell. The presented study reveals that this concept is able to maintain the supply for all typical DMFC operation conditions. Experimental results are presented that demonstrate the continuous operation of a passive muDMFC for more than 15 hours.