Study on proton-conducting solid oxide fuel cells with a conventional nickel cermet anode operating on dimethyl ether

This study investigates dimethyl ether (DME) as a potential fuel for proton-conducting SOFCs with a conventional nickel cermet anode and a BaZr _0.4Ce_0.4Y_0.2O_3-δ (BZCY4) electrolyte. A catalytic test demonstrates that the sintered Ni + BZCY4 anode has an acceptable catalytic activity for the decomposition and steam reforming of DME with CO, CH₄ and CO₂ as the only gaseous carbon-containing products. An O₂-TPO analysis demonstrates the presence of a large amount of coke formation over the anode catalyst when operating on pure DME, which is effectively suppressed by introducing steam into the fuel gas. The selectivity towards CH₄ is also obviously reduced. Peak power densities of 252, 280 and 374 mW cm^-2 are achieved for the cells operating on pure DME, a DME + H₂O gas mixture (1:3) and hydrogen at 700 °C, respectively. After the test, the cell operating on pure DME is seriously cracked whereas the cell operating on DME + H₂O maintains its original integrity. A lower power output is obtained for the cell operating on DME + H₂O than on H₂ at low temperature, which is mainly due to the increased electrode polarization resistance. The selection of a better proton-conducting phase in the anode is critical to further increase the cell power output.