Chemical and electrical properties of LSM cathodes prepared by mechanosynthesis

Abstract

Mechanosynthesis of La 1-x Sr x MnO 3 (x = 0, 0.25, 0.5, 0.75 and 1) was carried out at room temperature from stoichiometric mixtures of La 2 O 3 , Mn 2 O 3 and SrO, obtaining monophasic powders with the perovskite structure. Physical properties of these materials and their chemical compatibility with the electrolyte yttria stabilized zirconia (YSZ), which depend strongly on the La/Sr ratio, were evaluated to corroborate availability to be implemented as cathode material in solid oxide fuel cells (SOFCs).Electrical conductivity values in air ranged between 100-400 Scm -1 in the temperature range of 25-850 °C. Samples presented low reactivity with YSZ in the working temperature range (600-1000 ºC) maintaining the grain size small enough to preserve the catalytic activity for oxygen reduction.

Development by Mechanochemistry of La0.8Sr0.2Ga0.8Mg0.2O2.8 Electrolyte for SOFCs

“…The possibility of transferring increasing amounts of mechanical energy using high-energy ball milling equipment, such-as planetary mills, means that milling times can be shortened considerably, reducing the impurity content in the final product to admissible levels for a large number of applications. In this sense, in previous works [29,30], our research group synthesized the LSM system in just 90 min using high-energy milling conditions, demonstrating that mechanochemistry can be direct, cost-effective, time-saving, and suitable for large scale production.…”

“…In the case of the LSM sample (Figure 1b), all maxima were also indexed in a pseudo-cubic symmetry with a similar lattice parameter, a = 0.391 nm. It is known from the literature data that the LSM structure is rhombohedral (space group 167, R-3c; JCPDS Card N • : 1-085-2219), however, due to the large peak broadening, because of the small size of the coherent diffraction domains (D = 14 nm), the real symmetry could not be resolved [29,30]. In this case, La 3+ are substituted by 20% of Sr 2+ and the B positions are totally occupied by Mn 3+ (ionic radius = 1.645 pm).…”

“…It has been shown in previous studies that mechanochemistry is an appropriate method to synthesize complex solid solutions with a perovskite structure that can be used as an electrolyte [27,28] (LSGM system), cathode [29,30] (LSM system, La 1−x Sr x MnO 3 ), or anode [31] (SLT system, Sr 1−x La x TiO 3 ) in SOFCs. Mechanochemistry is a relatively simple process that uses the mechanical energy provided by ball mills to induce solid-state reactions at room temperature in a wide variety of powder reactant mixtures.…”

CGO20–CuO composites synthesized by the combustion method and characterized by H2-TPR

“…However, using the aforementioned materials, the fuel cell is expected to operate at 800ºC-1000ºC, which are too high for practical applications [3,4]. Moreover, despite exhibiting excellent electrocatalytic properties when operating with H 2 fuel, Ni-YSZ composite presents certain significant drawbacks, such as carbon deposition when the cell operates with hydrocarbon fuels, sulphur poisoning, Ni particle agglomeration and volume instability upon redox cycling [5,6].…”

Ultrasound and Microwave-Assisted Co-precipitation Synthesis of La0.75Sr0.25MnO3 Perovskite Nanoparticles from a New Lanthanum(III) Coordination Polymer Precursor

“…Hitherto, a variety of methods have been evolved for the preparation of LSM powders, such as solid-state reaction [3], ultrasonic spray pyrolysis (USP) [5], sol-gel technique [6], the polymeric precursor method (Pechini) [7], hydrothermal synthesis [8], co-precipitation [9], and combustion [4]. The present study deals with the preparation of LSM nanoparticles by three new successful co-precipitation routes assisted by ultrasonic and microwave irradiation of a La ( H] + = 2,6-diaminopyridinium, and (pydc) 2− = 2,6-pyridinedicarboxylate} as a novel precursor.…”