Tuning electrochemical performance and interfacial compatibility of oxygen electrodes in proton-conducting solid oxide electrolysis cells

Abstract

The growing demand for clean energy and the urgent need to reduce carbon emissions have accelerated the development of alternative energy solutions, with solid oxide electrochemical cells standing out owing to their efficiency in energy conversion between renewable energies and hydrogen. However, the slow reaction kinetics of its oxygen electrode, particularly at intermediate temperatures, impose a significant obstacle in optimizing their performance, reversibility, and durability. To address these challenges, this study introduces a new A-site deficient perovskite oxide as a potential electrode material for reversible protonic ceramic electrochemical cells. The cation deficiency effectively triggered the formation of oxygen vacancies and proton defects after hydration to facilitate multiple charge carrier conduction for enhanced electrode activity. After investigating the effects of cationic deficiency on structure and electrode polarization in a symmetric cell configuration of praseodymium nickel cobaltite perovskite (Pr_1−xNi_0.7Co_0.3O_3−δ), the optimal composition was confirmed and used for integration into full cells. The electrochemical performances in fuel cell and electrolysis modes were studied, and reversible operation and short-term stability test were conducted to understand the improved behaviors, providing a pathway to facilitate excessive proton conductivity for enhanced reaction activity in oxygen electrodes.