Suppressing Structure Delamination for Enhanced Electrochemical Performance of Solid Oxide Cells

Abstract

Reversible solid oxide cells (rSOCs) have significant potential as efficient energy conversion and storage systems. Nevertheless, the practical application of their conventional air electrodes, such as La0.8Sr0.2MnO3−δ (LSM), Ba0.5Sr0.5Co0.8Fe0.2O3‐δ (BSCF), and PrBa0.8Ca0.2Co2O5+δ (PBCC), remains unsatisfactory due to interface delamination during prolonged electrochemical operation. Using micro‐focusing X‐ray absorption spectroscopy (µ‐XAS), a decrease (increase) in the co‐valence state from the electrode surface to the electrode/electrolyte interface is observed, leading to the above delamination. Utilizing the one‐pot method to incorporate an oxygen‐vacancy‐enriched CeO2 electrode into these air electrodes, the uniform distribution of the Co valence state is observed, alleviating the structural delamination. PBCC–CeO2 electrodes exhibited a degradation rate of 0.095 mV h−1 at 650 °C during a nearly 500‐h test as compared with 0.907 mV h−1 observed during the 135‐h test for PBCC. Additionally, a remarkable increase in electrolysis current density from 636 to 934 mA cm−2 under 1.3 V and a maximum power density from 912 to 989 mW cm−2 upon incorporating CeO2 into PBCC is also observed. BSCF–CeO2 and LSM–CeO2 also show enhanced electrochemical performance and prolonged stability as compared to BSCF and LSM. This work offers a strategy to mitigate the structural delamination of conventional electrodes to boost the performance of rSOCs.

Enhancing the Oxygen Reaction Kinetics through Compositing BaCoO3-δ with Triple Conductor BaCo0.4Fe0.4Zr0.1Y0.1O3−δ for Proton-Conducting Solid Oxide Fuel Cells

“…In recent years, there has been a growing emphasis on composite oxides comprising multiple phases as air electrodes. − This effect enhances three-phase conduction and increases the number of active sites, thereby providing additional opportunities for the air electrode reaction and promoting advancements in electrochemical performance: the incorporation of an oxygen vacancy-enriched phase with a fluorite structure (Gd 0.1 Ce 0.9 O 2−δ or CeO 2 ) into the double perovskite (NdBa 0.5 Ca 0.5 Co 1.5 Fe 0.5 O 5+δ , PrBaCo 2 O 5+δ , or PrBa 0.8 Ca 0.2 Co 2 O 6−δ ) enables the realization of exceptional electrochemical performance and ensures a homogeneous distribution of metal ion oxidation states during prolonged electrochemical operations. − The nanocomposite, composed of Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3−δ (BSCF) with mixed O 2– /e – conductivity and BCFZY with H + conductivity, exhibits exceptional triple conductivity properties, including accelerated kinetics of oxygen surface exchange, enhanced bulk conductivity, stable crystal structure, and compatible thermal expansion behavior with the electrolyte . In another study, the utilization of a multiphase system comprising an exceptional mixed O 2– /e – conductor BaCoO 3−δ (BCO) and a conventional air electrode material (La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3−δ or PrBa 0.8 Ca 0.2 Co 2 O 6−δ ) demonstrates minimal polarization resistance and exceptional stability when employed in reversible protonic ceramic electrochemical cells. − Therefore, it is interesting to explore BCO as the O 2– /e – conducting phase in BCFZY-based composite air electrodes for PCFCs due to their potential synergistic effect among H + /O 2– /e – conduction mechanisms.…”