Optimal cell architecture for reversible solid oxide cells featuring rare-earth nickelate oxygen electrodes

Abstract

Improved performance in reversible electrochemical cells can be achieved by incorporating novel high-performance materials, or by optimizing electrode architectures employing known materials. In this work, we optimize the electrode architecture of a reversible solid oxide cell by tuning the oxygen electrode active layer (AL) and current collecting layer (CCL) thicknesses in reversible solid oxide cells that employ Nd2NiO4+δ and Nd0.5Ce0·5O2-δ (NNO-NDC50) composite electrodes. A detailed electrochemical performance analysis by impedance spectroscopy revealed that proper architectural design can significantly reduce the ohmic and polarization resistance. An optimum thickness of 27 μm for AL and 23 μm for CCL was found to result in an area-specific polarization resistance of 0.032 Ωcm2 in NNO|NNO-NDC50|GDC10|YSZ symmetrical half-cells. Single full cells with the optimized architecture Ni-YSZ|YSZ|GDC10|NNO-NDC50|NNO showed significant performance improvements in both fuel cell and electrolysis modes compared to state-of-the-art cells. A high power density of 1.54 Wcm−2 in the fuel cell mode was achieved with 97%H2–3%H2O fuel and air at 800 °C. The cell also achieved high current densities of 1.31272 Acm−2 and -1.25649 Acm−2 at 0.7 V and 1.2V respectively under 50% H2–50% H2O fuel and air at 800 °C, demonstrating its suitability for reversible power generation and electrolysis applications.