Durability and degradation of vapor-fed direct dimethyl ether high temperature polymer electrolyte membrane fuel cells

Abstract

Dimethyl ether (DME) combines high energy density with easy handling and low toxicity and is therefore an attractive fuel. The absence of carbon-carbon bonds allows for electro-oxidation with good kinetics and it is therefore particularly interesting for use in fuel cells. This work presents the first durability studies of vapor-fed direct dimethyl ether fuel cells with phosphoric acid doped polybenzimidazole membranes as electrolytes. Fuel cells are operated in direct DME mode at 160 and 200 °C and the cell voltage at a constant current load of 100 mA cm -2 is recorded over more than 200 h. Regular electrochemical impedance spectroscopy and polarization data are used as diagnostic measures to monitor the cell characteristics. It is shown that the cell performance deteriorates severely within 200 h of operation at 160 or 200 °C. The degradation is connected to different modes that ultimately result in both increasing polarization resistance and increasing area specific resistance, which may be connected to the chemical incompatibility between the fuel and the electrolyte.

Hydrogen Separation and Purification from Various Gas Mixtures by Means of Electrochemical Membrane Technology in the Temperature Range 100–160 °C

“…More specifically the formed NH 4 + ions react with the PO 4 3− groups, consequently resulting in a loss of conductivity. Similar to the results reported here, Vassiliev et al [ 68 ] reports on the possible chemical incompatibility between the other organic fuels and the electrolyte in HT membranes doped with PA. More specifically, it was concluded that the probable reasons were that the catalyst deactivation and/or acid depletion within the electrode occurred.…”

Performance degradation and mitigation of high temperature polybenzimidazole-based polymer electrolyte membrane fuel cells

“…59 Another mode of PA loss for cells operated with a direct feed of organic fuels, such as methanol or dimethyl ether, is the chemical formation of organic phosphate derivatives within the membrane. 68,69 These alkyl phosphates are less conducting and more volatile than the pure PA, and may be responsible for the relatively fast performance degradation of direct methanol and direct dimethyl ether HT-PEMFCs. 70 However, the relatively low methanol slip from the reformer for HT-PEMFCs has been found to have a very limited effect on the performance durability.…”