Solid oxide cells (SOCs) are promising sustainable and efficient electrochemical energy conversion devices. The application of a bilayer electrolyte comprising wide electrolytic oxide and highly conductive oxide is essential to lower the operating temperatures while maintaining high performance. However, a structurally and chemically ideal bilayer has been unattainable through cost-effective conventional ceramic processes. Here, we describe a strategy of naturally diffused sintering aid allowing the fabrication of defect-free doped-zirconia/doped-ceria bilayer electrolyte with full density and reduced interdiffusion layer at lower sintering temperature owing to the supply of small but appropriate amount of sintering aid from doped zirconia to doped ceria that makes the thermal shrinkages of both layers perfectly congruent. The resulting SOCs exhibit a minimal ohmic loss of 0.09 ohm cm2 and remarkable performances in both fuel cell (power density exceeding 1.3 W cm-2) and electrolysis (current density of -1.27 A cm-2 at 1.3 V) operations at 700°C.
Bibliographical noteFunding Information:
This work was supported by the Korea Institute of Energy Technology Evaluation and Planning (no. 20173010032140), Technology Development Program to Solve Climate Changes through the National Research Foundation (NRF) of Korea funded by the Ministry of Science, ICT & Future Planning (2017M1A2A2044982), and Korea Institute of Science and Technology (KIST) internal research programs (no. 2E30994 and 2E30995).
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