Electrical conductivity of Sr₂MgMoO_{6−δ} for solid oxide fuel cell anodes

Abstract

A high purity powder of Sr 2 MgMoO 6¹¤ (SMM) was synthesized by a solid-state reaction under atmosphere-controlled conditions. The powder was sintered at a relatively low temperature (1200°C) to prepare compacts with high grain boundary density. SMM is a promising anode material for solid oxide fuel cells and hence, the samples were characterized under conditions relevant to this application. The electrical conductivity values of SMM under various oxygen partial pressures ( p O2 = 10 ¹15 10 4.3 Pa) over the temperature range of 300 850°C were measured by AC impedance spectroscopy. The grain boundary resistivity and bulk resistivity exhibited different oxygen-partial-pressure-dependent behavior. Electron conduction is proposed as the primary mechanism for electrical conductivity in the bulk of the sintered body of SMM under both low and high oxygen partial pressures. Electron conduction and oxygen ion conduction were found to be the primary mechanisms for electrical conductivity at the grain boundary of SMM under low and high oxygen partial pressures, respectively.

Enhanced coking resistance of Ni cermet anodes for solid oxide fuel cells based on methane on‐cell reforming by a redox‐stable double‐perovskite Sr 2 MoFeO 6‐δ

“…In recent years, oxygen‐deficient and mixed‐valent perovskite materials have been shown to have a potential application as SOFC anode materials because of their appropriate catalytic activity and electro‐conductivity. For example, molybdenum‐based double perovskites Sr 2 MMoO 6‐δ (M = Co, Ni, Fe, Mn, and Mg) have exhibited excellent catalytic activity towards the electro‐oxidation of H 2 and CH 4 . Among these oxides, Sr 2 NiMoO 6‐δ shows desirable electrochemical performance even in dry CH 4 , which is attributed to the increased catalytic activity for methane conversion because of in situ exsolution of Ni .…”

“…For example, molybdenum-based double perovskites Sr 2 MMoO 6-δ (M = Co, Ni, Fe, Mn, and Mg) have exhibited excellent catalytic activity towards the electrooxidation of H 2 and CH 4 . [9][10][11][12] Among these oxides, Sr 2 NiMoO 6-δ shows desirable electrochemical performance even in dry CH 4 , which is attributed to the increased catalytic activity for methane conversion because of in situ exsolution of Ni. 13 As a result, stability of catalyst decreases at low oxygen partial pressures.…”

Chemical compatibility of Sr₂MgMoO_6−δ with representative electrolyte materials and interlayer materials for solid oxide fuel cells

“…15)27) In particular, Sr 2 MgMoO 6¹¤ (SMM) has been demonstrated to have excellent performance as an anode material for DIR-SOFCs. 16)18),20), 28) To develop the original performance of SMM, it is necessary to be chemically compatible with the electrolyte material at the time of electrode production and DIR-SOFCs operation. In the preparation of the electrode, annealing at 1300°C or higher is performed in the atmosphere, and the DIR-SOFCs are operated at a high temperature of about 700 to 1000°C in a reductive atmosphere.…”