Characterization of a membraneless direct-methanol micro fuel cell

Abstract

Abstract

The performance of a membraneless laminar flow micro fuel cell was evaluated under different operating conditions. The fuel cell was microfabricated in polydimethylsiloxane using standard soft-lithography techniques. It used methanol solution as the fuel for the anode side, and oxygen saturated sulphuric acid for the cathode. The parameters studied were the methanol concentration, flowrate, device width, and the concentration of sulphuric acid in the anode stream. Performance was characterized by V—I plots, stability of open circuit potential (OCP), polarization resistances, and anode polarization curves. We observed behaviour different from that shown thus far by existing laminar flow fuel cells. Our results show that the power output of the device decreases with an increase in the methanol concentration. An increase in the flowrate also decreases the power output of the device. It is shown that these trends are likely caused by the cell's internal resistance to proton transport. The addition of sulphuric acid to the fuel significantly decreases this resistance. It was found that the device OCP was not stable over extended operation, and could drop by more than 150 mV in 72 h.