Transient investigation of passive alkaline membrane direct methanol fuel cell

Passive direct methanol fuel cell (DMFC) is considered as an attractive power source for portable devices. In this study, a transient multiphase model for passive alkaline anion exchange membrane DMFC (AAEM-DMFC) is developed. The results show that the power density decreases during the operation and is more difficult to maintain stable with higher current density or lower voltage. The fuel efficiency increases with the increment of current density or the decrement of voltage. With a certain concentration, the optimal energy density is achieved at a moderate current density or voltage. Increasing the initial methanol concentration in reservoir can improve the energy density but decrease the fuel efficiency. Anode micro porous layer (MPL) can improve the fuel efficiency and increase the energy density with high initial concentration (or low current density) but cause negative effect on the energy density with low initial concentration (or high current density). Cathode MPL shows the similar but less significant effect. Generally, whether to use MPL should be determined by different operating conditions and the use demand. (C) 2016 Elsevier Ltd. All rights reserved.