Yttrium‐Doped Barium Zirconate‐Cerate Solid Solution as Proton Conducting Electrolyte: Why Higher Cerium Concentration Leads to Better Performance for Fuel Cells and Electrolysis Cells

Abstract

Proton conducting Y‐doped BaZrO 3, BaCeO 3 and their solid solutions are receiving increasing attention due to their promising application as electrolytes in ceramic fuel cells and electrolysis cells. However, the literature indicates a clear tendency that the performance of the cells increases with increasing Ce content in the electrolyte. In this work, to elucidate this phenomenon, a systematic work is performed on investigating the phase, hydration, and transport behaviors of BaZr 0.8−xCexY 0.2 O 3−δ (BZCY20). The results reveal that in the temperature range between 500 and 700 °C, with increasing Ce content, the dehydration temperature elevates and the proton concentration increases, showing that the Ce component favors the stabilization of protons. Furthermore, the transport number of hole conduction decreases, whereas the transport number of ionic conduction increases with the increasing Ce content. By further separating the contribution of oxide ions and protons, it is found that the oxide ion conductivity increases with the increasing Ce content at higher temperatures of 600 and 700 °C. Such decreased hole conductivity and increased oxide ion conductivity result in the enhancement of the ionic conduction of BZCY20 with increasing Ce content, and therefore improve the performance of fuel cells and electrolysis cells.