High Proton Conductivity in Sc-Doped BaZrO3: Effect of Dopant on Hydration Thermodynamics and Transport Behavior

Abstract

Proton conducting solid oxide electrolysis cells (SOECs) have great promise in converting renewable energies into hydrogen at intermediate temperatures (400~600 oC). The high efficiency and fast hydrogen production rate benefit from the proton conducting electrolyte with attractive proton conductivity and low activation energy. Transition element doped-BaZrO3 oxides have been widely employed as electrolyte because they show modest conductivity and high chemical stability in the realistic SOEC conditions. Still, the electrolyte development with higher proton conductivity is urgently needed to further reduce hydrogen production costs. In this work, a series of Sc doped BaZrO3 electrolytes are studied to understand the effects of the dopant, gas atmosphere and temperature on the hydration behavior and proton transport. The proton concentration, hydration thermodynamics and relevant characterizations are investigated to understand how the proton incorporation process is affected. The dehydration process can reveal that the protons have different stabilized positions in the lattice. Furthermore, the proton trapping can be also affected by the different dopant, which indicates the selection of the Zr-site doping should be balanced with consideration on proton concentration and migration energy simultaneously. This work will give some helpful insights into the design of proton conducting materials.