International Journal of Hydrogen Energy, Vol.45, No.8, 5554-5564, 2020
High performance and stability of nanocomposite oxygen electrode for solid oxide cells
Solid oxide electrochemical cell (SOC) is a highly promising alternative for fuel conversion and power-to-gas due to its high efficiency and low emission. However, degradation resulting from the electrolyte-electrode interface is a major challenge in both fuel cell mode and electrolysis mode. Here, a co-sintering tri-layer structure cell with nano composite oxygen electrode is developed to mitigate the interface issue. A 10 x 10 cm(2) NiO/YSZ lYSZ lYSZ-La0.6Sr0.4Co0.2Fe0.8O3-25 (LSCF) cell has been conducted under different fuels in SOFC mode. A power density output of 558 mW/cm(2) @0.7 V-800 degrees C in wet H-2 and a durability of 300 h in simulated syngas have been obtained. The performance of LSF, LSCF and SSC oxygen electrodes have been studied in both SOFC and SOEC modes. It suggests that three oxygen electrodes have an order of SSC > LSCF > LSF in electrochemical performance, and an opposite order in stability of SOEC. The degradation of the LSCF and SSC can be derived from the solid-state reactions at the interface between Co-containing perovskites and YSZ during operation. It demonstrates that GDC and Ag modification can enhance the oxygen elettro destability by impeding the soli state reactions and the nanoparticles sintering. Results suggest that GDC has a negative effect on the cell performance and Ag has a positive effect, implying that enhancing the electric conductivity of YSZ-LSCF is the key to improve the cell performance. Moreover, cell with YSZ-SFM/GDC has been applied in CH4 assisted SOEC process (CH4-SOEC), in which a significant reduction of electricity consume can be realized. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.