Comprehensive characterization and understanding of micro-fuel cells operating at high methanol concentrations

We report on the analysis of the performance of each electrode of an air-breathing passive micro-direct methanol fuel cell (µDMFC) during polarization, stabilization and discharge, with CH(3)OH (2–20 M). A reference electrode with a microcapillary was used for separately measuring the anode the cathode potential. Information about the open circuit potential (OCP), the voltage and the mass transport related phenomena are available. Using 2 M CH(3)OH, the anode showed mass transport problems. With 4 and 6 M CH(3)OH both electrodes experience this situation, whereas with 10 and 20 M CH(3)OH the issue is attributed to the cathode. The stabilization and fuel consumption time depends mainly on the cathode performance, which is very sensitive to fuel crossover. The exposure to 20 M CH(3)OH produced a loss in performance of more than 75% of the highest power density (16.3 mW·cm(−2)).