Functionality of an oxygen Ca3Co4O9+δ electrode for reversible solid oxide electrochemical cells based on proton-conducting electrolytes

Reversible solid oxide cells (rSOCs) based on proton-conducting electrolytes represent an advanced electrochemical technology aimed at reversible energy conversion. Their high levels of efficiency, minimal impact on the environment and economic viability point to a positive future for rSOCs. In this study we present the results of electrochemical characterization of the Ca3Co4O9+delta-based oxygen (or steam) electrodes for rSOCs with the BaCe0.5Zr0.3Y0.2O3-delta electrolyte. The electrodes developed display excellent electrochemical activity both in the symmetrical and reversible cells. In detail, the electrode polarization resistance at 700 degrees C amounts to less than 0.25 Omega cm(2) after long-term measurements (1500 h, symmetrical cell mode of operation) and lower than 0.13 Omega cm(2) (open circuit voltage mode of operation), exceeding the electrode performances of other Co-based materials of "112" (LnBaCo(2)O(5+delta), Ln is the lanthanide) and "114" (YBaCo4O7+delta) families. Analysis of these data shows that Ca3Co4O9+delta can be considered to be a promising alternative to the state-of-the-art electrodes utilized in protonic ceramic fuel and electrolysis cells.