Ceria-based electrolytes, namely Gd-doped ceria (CGO), are currently used as IT-SOFC electrolytes. The addition of an alkaline carbonate phase was already considered to enhance the conductivity and decrease the sintering... [ view full abstract ]
Ceria-based electrolytes, namely Gd-doped ceria (CGO), are currently used as IT-SOFC electrolytes. The addition of an alkaline carbonate phase was already considered to enhance the conductivity and decrease the sintering temperature of this material. Composites based on CGO (ceramic porous backbone) and a mixed alkaline carbonate phase (infiltrated in the pores) are also interesting for CO2 separation membranes (1-2). However, the standard production of strong ceramic matrices with tuned microstructure/porosity involves high processing temperatures.
In this work porous CGO matrices were fabricated at low temperature (<1100 °C) using a eutectic mixture of Na and Li salts (NLS) as sintering aids. The effect of the sintering aid (carbonates or nitrates) on the microstructure was investigated by scanning electron microscopy (SEM). Electrical assessment using the porous matrix and/or dense CGO/NLS composites involved impedance spectroscopy measurements performed in air up to 600 °C, and at higher temperature (600-750 °C) within an extended range of oxygen partial pressures (0.21 to below 10-20 atm).
Depending on sintering temperature and admixture, microstructures ranged from porous to almost fully dense, with grain growth assisted by the sintering aid. The electrical performance showed modest deviation from standard CGO electrolytes. The strong CGO/NLS matrices hereby developed may be an alternative to complex processing routes (e.g., replica, direct foaming, sacrificial template).
Acknowledgement: Funding from projects CO2ZERO (POCI-01-0145- FEDER-016654 - PTDC /CTM -CER/6732/2014) and CICECO‐Aveiro Institute of Materials (FCT UID/CTM/ 50011/2013), Portugal FCT/MEC PIDDAC and co-financed by FEDER under the COMPETE 2020 Program, and from CNPq (Program Ciência sem Fronteiras, Brazil).
(1) J.L. Wade, K.S. Lackner, A.C. West, Solid State Ionics, 178 (2007) 1530-1540.
(2) F.M.B. Marques, S.G. Patrício, E. Muccillo, R. Muccillo, Electroch. Acta, 210 (2016) 87-95
Energy Generation (SOFC, PCFC, PV, ...) , Energy Conversion , Membranes for gas separation , Processing , Conduction of electrons and ions
