High performance direct methanol fuel cells with micro/nano-patterned polymer electrolyte membrane

The effect of an enlarged specific surface area of the membrane with well-defined line patterns on the performance of a direct methanol fuel cell (DMFC) is investigated and compared with the baseline pristine Nafion 115 membrane. Line patterns with dimensions ranging from several tens of nanometers to several micrometers were fabricated on Nafion 115 membranes with high reliability using thermal imprint lithography to ensure an uncollapsible structure. In the case of quasi-nano-patterned membrane the cell performance increased about 35% compared with that of the pristine Nafion 115 membrane owing to an increased effective three-phase boundary caused by an enlarged specific surface area. Thus the performance of DMFCs can be improved further by controlling the shape and size of the line patterns for sufficient formation of the three-phase boundary.