Dual-phase electrolytes for advanced fuel cells

Double-phase electrolyte (DPE) consisting of doped CeO2/NiAl solid phase and NaOH liquid phase was used for fuel cells utilizing LiNiO2 anode and Ag cathode at working temperatures over 450 degrees C. It was shown that the cells can produce a maximum output power of 716.2 mW cm(-2) at 590 degrees C even though utilized with relatively large thickness of electrolyte, from 0.8 to 1.2 mm. Most measurements of open circuit voltage (OCV) range between 1 and 1.2 V; a significantly higher OCV value of 1.254 V was also obtained. Liquid channel conductive mechanism of NaOH in DPE is proposed; both O2- and H+ concur to conduct the current; the doped CeO2 transports O2- ions, whereas the molten second phase transports H+ protons. Moreover, SEM observations and EDS analysis suggest that Na+ and OH- also contribute to enhance both OCV and output power of our cells. The addition of NiAl to the doped CeO2 increases the mechanical strength and the output power of DPE; however the reasons of this latter effect are still to be further investigated. The results show that DPE is a promising electrolyte to manufacture fuel cells with advanced performances. (c) 2005 Elsevier B.V. All rights reserved.