A novel approach for substantially improving the sinterability of BaZr0.4Ce0.4Y0.2O3-delta electrolyte for fuel cells by impregnating the green membrane with zinc nitrate as a sintering aid

Abstract

BaZr0.4Ce0.4Y0.2O3-delta (BZCY4) has been widely considered to be a promising electrolyte material for H+ - SOFC, but it is restricted to commercial applications due to its poor densification behavior. A dense BZCY4 pellet was obtained by sintering at 1250 degree Celcius after impregnating the material with a zinc nitrate solution.The dilatometer curves and scanning electron microscopy (SEM) images indicated that the sinterability of the BZCY4 material is effectively improved by impregnating the green membrane with 4wt% Zn. Moreover, EDX mapping indicated that the Ba, Zr and Ce elements were homogeneously distributed in the BZCY4+4 wt%Zn sample sintered at 1250 degree Celcius . In addition, an integrated SOFC employing a BZCY4+4 wt% Zn electrolyte was successfully fabricated without any cracks and delamination by impregnating the BZCY4 electrolyte membrane with zinc nitrate as a sintering aid. This single cell with a 25mm thick BZCY4+4 wt% Zn electrolyte membrane exhibited power densities as high as 360 and 276 mWcm-2 at 700 and 600 degree Celcius , respectively. Electrical conductivity measurements demonstrated that the total conductivities of BZCY4+4 wt% Zn were 0.46*10-2 S cm-1, 0.56*10-2 S cm-1,0.20*10-2 S cm-1 and 0.40*10-2 S cm-1 at 600 degree Celcius in air, wet air,10% H2–Ar and wet 10% H2–Ar, respectively.