Air-breathing fuel cells fed with dimethoxymethane (DMM) vapor

The dimethoxymethane vapor-fed fuel cell (V-DMMFC) described in this paper is an innovative design for passive water management without the need for a complex micro-fluidic subsystem. DMM is a promising fuel for vapor-fed fuel cells because it has high energy density, an absence of C–C bonds, and lower toxicity as well as high vapor pressure. In a polarization measurement, the V-DMMFC showed an open circuit voltage of around 0.55 V and a high power density of 34.7 mW cm−2 at 0.315 V, which is higher than that of a fuel cell with MeOH vapor. The V-DMMFC achieved a fast response in fuel feeding and a higher Faradic efficiency (76.1%) than that of fuel cells fed with MeOH vapor (53.7%); these improvements result from a higher vapor pressure and a lower fuel crossover of DMM. For constant voltage (CV) mode, the V-DMMFC provided evidence for the long-term stability of the device and for the sustainability of humidity within the self-humidified MEA without any additional provision of water.