3.1.3. Electrochemical characterization of MEAs
Fig. 5(a) shows the IeV curves of the MEAs hot-pressed at
1.0e4.0 MPa. These single-cell polarization curves were taken
at 60 C under ambient pressure by feeding a 1.0 M methanol
solution to the anode and dry air to the cathode. Similar open
circuit voltages are observed for all MEAs with a value of about
0.8 V, which indicates that they experience approximately the
same amount of methanol crossover. The DMFC performance
improves with an increase in pressure of up to 3.0 MPa and
then declines with a higher pressure of 4.0 MPa. The best
performance is obtained at 3.0 MPa where the maximum
power density is around 106 mW cm2. The difference in
performance is more pronounced in a high current density
range, which corresponds to the mass transfer region and is