Evaluation of NdBaCo2O5+δ oxygen electrode combined with negative expansion material for reversible solid oxide cells

The mismatch of thermal expansion between the oxygen electrodes and the electrolytes is still a critical issue, which leads to the degradation of performance for solid oxide cells (SOCs) or even the damage to cells during the long-term operation. Here, we propose a strategy to achieve complete thermomechanical compatibility between NdBaCo 2 O 5+δ (NBC) electrode and other cell components by introducing NdMnO 3-δ (NM), a negative thermal expansion (NTE) oxide. During the thermal cycling process, the negative expansion material alleviates the shear and tensile stresses of the NBC electrode in a three-dimensional space. Whereafter, the “buffer effect” significantly improves the thermal cycling stability of the composite electrode. The results of electrochemical impedance spectroscopy and microstructure observation also confirmed that the significant improvement in thermal stability is mainly related to a better bonding ability between the oxygen electrode and the electrolyte.