Study on a Passive Vapor Feed Direct Methanol Fuel Cell with High Methanol Concentration

Abstract

Abstrac t—An extensive research has been carried out to improve the performance of direct methanol fuel cells (DMFCs) using low methanol concentration below 5 M either in active or passive conditions due to methanol crossover (MCO) problem which the methanol crosses over the membrane and reacts directly with oxygen at cathode. However, a low methanol concentration leads to a low energy density of the fuel cell system and a short runtime which cannot meet the requirement of commercialization. Therefore, it is important to use a high concentration of methanol in DMFC to achieve a high energy density. This study was done to improve the performance of passive vapor feed DMFC by using high methanol concentrations from 12 M (molarity) to neat methanol. From the results obtained, it was showed that the performance of passive vapor feed DMFC that used high methanol concentration improved. It was a linear dependence of current density on methanol concentration which is the current density increased when the methanol concentration increased up to neat. The linear dependence of current density on the concentration suggested that the cell operation was under the rate controlling by the methanol transport. Therefore, it can conclude that high methanol concentration can leads to high energy density achieved by the DMFCs.