Issue 2, 2011

Thermodynamic and electrical characteristics of NdBaCo2O5 at various oxidation and reduction states

Abstract

A solid oxide fuel cell is a device that converts the chemical energy in fuel to the electrical energy directly, efficiently and eco-friendly. The cation ordered perovskite-related oxide, NdBaCo2O5 (NBCO), is known as one of the best cathode materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs) because of their superior electrochemical properties. The aim of this work is to identify the crucial characteristics of NdBaCo2O5/YSZ composites, such as the redox properties, the structures, and the electrical conductivities for a new cathode material for IT-SOFCs. Thermodynamic redox properties including oxidation enthalpies and entropies were investigated by coulometric titration. The isotherms were obtained at 923, 973 and 1023 K over a wide range of p(O2). Oxygen non-stoichiometries have shown that higher temperatures lead the composites to a deeper reduction state rapidly near the p(O2) of 10−5 atm and at 1023 K, which can be the sign of the decomposition. Therefore, the NBCO-YSZ composites may not be suitable for the cathodes of SOFCs above operating temperatures of 1023 K due to the decomposition. The oxidation enthalpies and entropies were determined from the isotherms and the electrical conductivities measured by the 4-probe method were high enough for IT-SOFC cathode applications.

Graphical abstract: Thermodynamic and electrical characteristics of NdBaCo2O5+δ at various oxidation and reduction states

Article information

Article type
Paper
Submitted
06 Jun 2010
Accepted
06 Sep 2010
First published
27 Oct 2010

J. Mater. Chem., 2011,21, 439-443

Thermodynamic and electrical characteristics of NdBaCo2O5 at various oxidation and reduction states

S. Yoo, J. Y. Shin and G. Kim, J. Mater. Chem., 2011, 21, 439 DOI: 10.1039/C0JM01779E

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