Optimizing the modification method of zinc-enhanced sintering of BaZr _0.4Ce_0.4Y_0.2O_3-δ-based electrolytes for application in an anode-supported protonic solid oxide fuel cell

The effects of zinc modification methods on membrane sintering, electrical conductivity of BaZr_0.4Ce_0.4Y_0.2O _3-δ (BZCY4) and the thermo-mechanical match of the BZCY4 electrolyte with anode were systematically investigated. Three modification methods are pursued, including the physical mixing of BZCY4 with a ZnO solid (method 1), introducing zinc during the solution stage of the sol-gel synthesis (method 2) and doping zinc into a perovskite lattice by synthesis of a new compound with a nominal composition of BaZr_0.4Ce_0.4Y _0.16Zn_0.04O_3-δ (method 3). Method 1 turned out to be the most effective at reducing the sintering temperature, which can mainly be attributed to a reactive sintering although ZnO doping into the BZCY4 lattice also facilitates the sintering. While all three modification methods facilitated the membrane sintering, only the electrolyte from method 3 had similar shrinkage behavior to the anode. An anode-supported thin-film BZCY4-3 electrolyte solid oxide fuel cell (SOFC) was successfully fabricated, and the fuel cell delivered an attractive performance with a peak power density of ∼307 mW cm^-2 at 700 °C.