Comparison of the membrane-electrode assembly conditioning procedures for direct methanol fuel cells

The effects of four conditioning procedures, i.e. methanol circulation, combination of methanol circulation and electric load, methanol circulation plus gas evolution, and H2/O2 PEMFC mode, on the electrochemical behaviors and performances of membrane-electrode assemblies (MEAs) in direct methanol fuel cells (DMFCs) have been comparatively investigated for maximizing their performances. The results show that the conditioning procedures do not have much influence on the catalytic activity, oxygen transport, and proton resistance in the catalyst layer. However, the conditioning procedures have significant influence on the hydration of the MEAs, which determines the electrochemical performances of the MEAs before eventually reaching their maximum performances. Among the various procedures investigated, the combination of methanol circulation and electric load is a convenient and effective in situ way to activate the fresh MEAs in DMFC, which speeds up the hydration of the MEAs due to large amount of water on both electrodes.

► Effects of pretreatment procedures on MEAs.
► Pretreatment improves MEA activity toward MOR and ORR.
► The passages for electrons, protons, and reactants oriented through electric load.
► Maximum power density achieved through electric load.