A passive vapor-feed direct methanol fuel cell based on a composite pervaporation membrane

A passive micro direct methanol fuel cell (μDMFC) by using composite pervaporation membrane for vapor fuel supply without any extra power is presented. A simple and power free vaporizer based on composite pervaporation membrane, which consists of a PDMS active layer and a porous silicon support layer, is integrated with a μDMFC, converting the methanol from liquid phase to vapor phase. The novel anode structure generates methanol vapor, which diffuses to and reacts with catalyst directly. The prototype can exhibit a fuel efficiency of 78.4%, higher than other reported passive μDMFCs, and a large energy density of about 1020 Wh L^-1, which is 1.5 times higher than the reported liquid fed passive DMFCs. It is believed that the vapor-feed μDMFC will be more applicable for micro systems.