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 °C. It was shown that the cells can produce a maximum output power of 716.2 mW cm−2 at 590 °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.