Optimization and Durability of Reversible Solid Oxide Cells

Reversible solid oxide cells (rSOCs) hold a considerable potential to play a very important role in the future energy system. The present work focuses on understanding the influence of initial cell performance, duration of the operation when cycling between SOFC and SOEC modes, current density and temperature on the durability of rSOCs. Two different cell designs are developed and their performance in reversible operation was evaluated. Type I is Ni-yttria stabilized zirconia (Ni-YSZ) fuel electrode supported planar SOCs, with a LSC-CGO (La0.6Sr0.4CoO3-δ-Ce0.9Gd0.1O2-δ) composite oxygen electrode, Type II is the same fuel-electrode supported half-cell with CGO oxygen electrode backbone infiltrated with LSC nano-electrocatalysts. Comparable degradation rates of below 5-10%/1000 hours were achieved for Type I cells operated at ±0.5 A/cm2, or for Type II cells operated at ±1.25 A/cm2. The electrochemical performance and durability of both cell types are compared and the observed degradation behavior is discussed.