The rate determining step of energy conversion in state-of-art SOFCs at intermediate temperature (IT) is the sluggish kinetics of oxygen reduction reaction (ORR) in the cathode, and thus the cathode material significantly affects performances of IT-SOFCs. Up to now, cobalt-based perovskite oxides have received great attentions for the cathode material because of the low overpotential for ORR. [2]. However, cobalt-based materials have significantly high thermal expansion coefficient (TEC) values ( ), compared to those of typical electrolytes (yttria-stabilized zirconia and rare-earth-doped ceria, ). This big discrepancy gives rise to mechanical stress to the cell, which affects the long-term stability of cells [3]. Furthermore, cobalt-based materials are expensive and have a low stability under reducing atmospheres. In contrast, the TEC of lanthanum nickelates (Lan+1NinO3n+1) is , which is nearly analogous to the TEC of electrolyte materials [4]. In addition, lanthanum nickelates have high electrical conductivity with the great stability at IT. In this work, the performance and durability of lanthanum nickelates are investigated in the anode-supported cell design and analyzed by using various tools such as TEM, XPS, and DFT calculations [5].
References
[1] K.T. Lee, E.D. Wachsman, Science 334 (2011) 935.
[2] W. Zhou, Z. Shao, J. Power Sources 192 (2009) 231
[3] S. Pang, X. Xi, J. Power Sources 326 (2016) 176.
[4] R.K. Sharma, E. Djurado, J. Power Sources 325 (2016) 337.
[5] T.H Lee, J.-Y. Park. J. Power Sources 331 (2016) 495
Keywords: Solid oxide fuel cells; Lanthanum nickelate; Thermal Expansion Coefficient; Conductivity, Stability