Electrochemical performance of strontium-doped neodymium nickelate mixed ionic–electronic conductor for intermediate temperature solid oxide fuel cells

• Published in: Journal of solid state electrochemistry 2013-03, Vol.17 (3), p.617-626
• Main Authors: Khandale, A. P., Punde, J. D., Bhoga, S. S.
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Condensed Matter Physics; Electrochemistry; Energy Storage; Original Paper; Physical Chemistry
• ISSN: 1432-8488; 1433-0768
• DOI: 10.1007/s10008-012-1892-3

The Nd 2 −  x Sr x NiO 4 +  δ ( x  = 0.1–0.5) solid solutions prepared by combustion synthesis are of submicron/superfine crystallite size. The crystal structure estimated by Rietveld analysis reveals increase in space in the rock salt layer on partial replacement of Nd 3+ by Sr 2+ . The transition from negative temperature coefficient to positive temperature coefficient of conductivity is observed at 913 K. The maximum dc conductivity ( σ  = 1.3 ± 0.02 S cm −1 at 973 K) is obtained for x  = 0.2 in Nd 2 −  x Sr x NiO 4 +  δ . The low dc conductivity compared with reported (≈100 S cm −1 ) is due to high porosity (low relative density) resulting from agglomeration of submicron crystallites. The variation in the conductivity with Sr content in Nd 2 −  x Sr x NiO 4 +  δ is understood on the basis of defect chemistry. The electrochemical properties of the cathode materials are studied using electrochemical impedance spectroscopy at various temperatures and oxygen partial pressures. Nd 1.8 Sr 0.2 NiO 4 +  δ cathode exhibits lowest-area-specific resistance = 0.52 ± 0.015 Ohm cm 2 at 973 K. At low (