Effect of Ca doping at A or B sites on electrochemical performance of La1.9In0.1Ce2O7 proton conductors

Fluorite proton conductors La1.8In0.1Ca0.1Ce2O7-delta and La1.9In0.1Ce1.9Ca0.1O7-delta (LICaC and LICCa) were synthesized by solid state reaction. The effect of Ca doping at A site or B site on La1.9In0.1Ce2O7 was studied by X-ray diffraction (XRD), Inductively Coupled Plasma Mass Spectrometry (ICP), scanning electron microscopy (SEM) and electrical conductivity measurement. XRD shows that the LICaC and LICCa were successfully synthesized, and Ca was doped to the expected sites. The measured mass ratios of each element by ICP were in good agreement with their theoretical values. In addition, SEM also found that the surface of the sample was dense without holes. The conductivities of LICaC and LICCa were studied at 400-800 degree celsius, and their highest conductivities were 7.28x10(-4) and 5.56x10(-3) S<middle dot>cm(-1), respectively. The conductivity of LICCa doped at the B site is better than that of LICaC doped at the A site. In the wet air at 800 degree celsius, the proton transference numbers of LICaC and LICCa are 0.5 and 0.52, respectively. LICaC and LICCa were used as electrolytes to prepare fuel cells and their performance was tested. The electrolyte thickness of LICAC and LICCA was about 0.9 mm. At 700 degree celsius, the maximum power density of LICaC and LICCa electrolyte-based single cells are 124.51 and 162.26 mW cm(-2), respectively. The results show that LICCa has good proton conductivity and has potential as an electrolyte for high-performance fuel cells.