Suppressing Structure Delamination for Enhanced Electrochemical Performance of Solid Oxide Cells

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 La_0.8Sr_0.2MnO_3-δ (LSM), Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ (BSCF), and PrBa_0.8Ca_0.2Co₂O_5+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.