Microwave sintering coupled with sintering aids for proton-conducting oxide membranes

Abstract

The BaCe0·4Zr0·4Y0·2O3 (BCZY) was modified with the NiO sintering aid and prepared by a microwave sintering (MVS) method as the electrolyte for proton-conducting solid oxide fuel cells (H–SOFCs). The incorporation of NiO into the BCZY lattice improves the sinterability of the material, leading to the increase of the shrinkage from 3% to 26% after the high-temperature sintering. The dense BaCe0·4Zr0·4Y0·15Ni0·05O3 (BCZYN) pellet can be obtained after sintering at 1500 °C, whereas the Ni-free BCZY is porous after sintering at the same condition. By further using the MVS method, the BCZYN can be densified at 1300 °C, which is 200 °C lower than conventional sintering. Furthermore, the microwave-sintered BCZYN has a higher conductivity than the conventionally sintered one due to the larger grain size. Using the MVS method in the H–SOFCs fabrication, the high porosity of the anode substrate can be retained. In contrast, the cell prepared by the conventional sintering (CS) method has a relatively dense anode, which is detrimental to gas fuel transportation. As a result, the microwave sintered cell exhibits an output of 1010 mW cm−2 at 700 °C, which is significantly larger than that for the conventionally sintered cell, being 535 mW cm−2 at the same testing condition, suggesting the advantage of using the MVS method for the fuel cell fabrication.