Performance and Degradation of Electrolyte Supported SOECs with Advanced GDC Thin-film Layers in Long-term Stack Test

Electrolyte supported Solid Oxide Cells (ESCs) with advanced thin-film Gd-doped ceria layers deposited via EB-PVD method at 600 o C were assembled and electrochemically investigated in a so-called “rainbow” stack with 30 repeat units (RUs). At the initial stage of the SOEC operation, the stack reached a high performance with an electrical efficiency of 99.65 % at 75 % steam conversion and a total power input of 1.98 kW. A long-term stack test was performed in SOEC mode for over 5000 h and demonstrated a low voltage degradation of approx. +10.9 mV·kh –1 per RU (+0.9% kh –1 ). The RUs with EB-PVD GDC thin-films demonstrated similar initial performance and degradation rate to the state-of-the-art cells. In this paper, the investigation mainly focuses on the electrochemical characteristics of RUs containing the EB-PVD thin-film GDC layers.