Investigation of Fabrication Methods to Enhance Proton Conductivity in Ba(Zr0.4Ce0.4Y0.1Yb0.1)O3 electrolytes for Solid Oxide Electrolysis Cells Using Sintering Aids

High-temperature solid oxide cells (SOCs) can be reversibly operated as fuel cells (SOFCs) or as electrolyzer cells (SOECs) for applications like water splitting or syngas production. SOECs are particularly attractive due to their high electrical-to-chemical energy conversion efficiencies, making them ideal for hydrogen or syngas production in renewable energy contexts, such as "power2gas." Among ABO₃ perovskite-type proton conductors, Ba(Zr_0.4Ce_0.4Y_0.1Yb_0.1)O₃ exhibits a relatively high conductivity of 0.013 S cm⁻¹ at 600°C. However, its densification at low temperatures is challenging, requiring sintering at 1500–1700°C to achieve a high relative density. Such high sintering temperatures can lead to problems like BaO evaporation, phase segregation, and Ni diffusion, all of which reduce proton conductivity and affect the cell’s performance. This project aims to develop a Ba(Zr_0.4Ce_0.4Y_0.1Yb_0.1)O₃ electrolyte with high protonic conductivity for proton-conducting solid oxide electrolysis cells. By using sintering aids like ZnO, Y₂O₃, and BaO, we propose different fabrication methods to transfer from Ba(Zr_0.4Ce_0.4Y_0.1Yb_0.1)O₃ electrolyte pellets to apply on NiO anode in order to enhance the densification process and reduce grain boundary resistance. In this research, different wt% of ZnO, Y₂O₃, and BaO were added to Ba(Zr_0.4Ce_0.4Y_0.1Yb_0.1)O₃, leading to improvements in conductivity and grain size. The effects of these additives on the relative density, microstructure, and electrochemical performance of the electrolyte for steam electrolysis were investigated, showing increased conductivity and enhanced electrochemical performance. The phase purity and proton conductivity of the electrolyte were also measured and analyzed.