Innovative solid oxide fuel cells based on BaIn0.3Ti0.7O2.85 electrolyte and La2Mo2O9 amorphous reduced phase as anode material

Buvat, Gaëtan; Quarez, Éric; Joubert, Olivier

doi:10.1016/j.jpowsour.2015.10.030

Cited by 13 publications

(5 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…23 These successes have led to further investigation of the utility of these materials in SOFCs as both the electrolyte 24-26 and the anode. [27][28][29] Investigation into the precise mechanisms of conduction in La2Mo2O9, on the other hand, has been relatively sparse. Initially it was assumed that the partially occupied O2 and O3 sites were the cause of conductivity, with the O1 sites remaining static.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Direct Observation of Oxide Ion Dynamics in La₂Mo₂O₉ on the Nanosecond Timescale

et al. 2017

View full text Add to dashboard Cite

Quasielastic neutron scattering (QENS), underpinned by ab-initio molecular dynamics (AIMD) simulations, has been used to directly observe oxide ion dynamics in solid electrolyte La 2 Mo 2 O 9 on the nanosecond timescale, the longest timescale probed in oxide ion conductors by neutron scattering to date. QENS gives the activation energy of 0.61(5) eV for this process, while AIMD simulations reveal that the exchange processes, which ultimately lead to long-range oxide ion diffusion in La 2 Mo 2 O 9 , rely on the flexibility of the coordination environment around Mo 6+ , with oxide ions jumps occurring between vacant sites both within and between Mo coordination spheres. Simulations also differentiate between the crystallographic sites which participate in the oxide ion exchange processes, offering the first atomic-level understanding of the oxide ion dynamics in La 2 Mo 2 O 9 , which is consistent with the macroscopic experimental observations on this material.

show abstract

Section: Introductionmentioning

confidence: 99%

“…In addition, the phase transition has been shown to be suppressed in La 2 Mo 2 O 9 nanowires which also show extremely high conductivity . These successes have led to further investigation of the utility of these materials in SOFCs as both the electrolyte − and the anode. − …”

Section: Introductionmentioning

confidence: 99%

Direct Observation of Oxide Ion Dynamics in La₂Mo₂O₉ on the Nanosecond Timescale

et al. 2017

View full text Add to dashboard Cite

show abstract

“…In any case, these results seem to confirm the instability of the amorphous phase La 2 Mo 2 O 7– y in a reductive atmosphere. However, when amorphous La 2 Mo 2 O 7– y was tested as anode in a SOFC device, negligible losses in electrical properties were observed for over 4 days and even for over 30 days . This suggests that the amorphous phase was stable under the reducing atmosphere of a SOFC in operating conditions.…”

Section: Resultsmentioning

confidence: 98%

“…However, when amorphous La 2 Mo 2 O 7−y was tested as anode in a SOFC device, negligible losses in electrical properties were observed for over 4 days 11 and even for over 30 days. 13 This suggests that the amorphous phase was stable under the reducing atmosphere of a SOFC in operating conditions. Determinant effects as anodic overpotential, oxide ion migration from the electrolyte, or water vapor emission during fuel cell operation might lead to stabilization of the amorphous phase.…”

Section: ■ Results and Discussionmentioning

confidence: 98%

“…11 Therefore, so far, the most promising applications of La 2 Mo 2 O 9 -derived materials in SOFC devices are either for oxidized forms as electrolyte in single-chamber devices 12 (with less stringent reducing conditions) or for reduced amorphous form as anode material in double-chamber devices. 11,13 Very recently, Liu et al 14 showed that La 2 Mo 2 O 9 nanowires prepared by electrospinning exhibit a 3 orders of magnitude increase of ionic conductivity with respect to the bulk material. They attribute most of this increase to the presence of a highly conducting surface layer of strained amorphous phase with composition La 2 Mo 2 O 8.5 around the nanowires.…”

Section: ■ Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Reduction Kinetics of La₂Mo₂O₉ and Phase Evolution during Reduction and Reoxidation

et al. 2016

Self Cite

View full text Add to dashboard Cite

An amorphous reduced form of oxide ion conductor La2Mo2O9 had been proposed as sulfur-tolerant anode material for solid oxide fuel cell, but its oxygen content was not known. In this paper, we investigate the reduction kinetics by diluted hydrogen of La2Mo2O9 to amorphous, and the oxygen range of the amorphous form. The reduction kinetics is studied as a function of the powder specific surface area and of the temperature, on powders synthesized by solid state reaction and by polyol process using two different solvents. The reduction process was carried out by TGA under 10% H2 diluted in argon, and its kinetics is analyzed and modeled. As expected, small particles and high temperature lead to higher reduction rates. Several reduction steps were identified by XRD during the process. At 700 °C La2Mo2O9 is directly reduced into the amorphous phase La2Mo2O7-y, whereas at 760 °C reduction occurs through an intermediate crystallized La7Mo7O30 (≅ La2Mo2O8.57) phase before amorphization. In both cases, further reduction of La2Mo2O6.2 amorphous phase leads to an exsolution of metallic molybdenum and a molybdenum deficiency in the amorphous phase. Reoxidation of amorphous La2Mo2O7-y was studied by TGA, DTA and XRD. At low temperature in air, the reduced compounds are reoxidized while remaining amorphous. The annealing for 60 h at 350 °C in air of reduced La2Mo2O6.66, obtained beforehand by solid state reaction, gives an amorphous phase with composition La2Mo2O8.85. The existence domain of the reduced amorphous phase in terms of oxygen content therefore ranges at least from O6.2 to O8.85, thus including the composition La2Mo2O8.50 of the amorphous surface layer at the origin of a huge increase of ionic conductivity recently reported in nanowires of La2Mo2O9.

show abstract

Cationic Interdiffusion at the SOFC Electrolyte/Cathode Interface in La₂Mo₂O₉/La_0.8Sr_0.2MnO_3‐δ

et al. 2017

View full text Add to dashboard Cite

In this work cation diffusion between a La 2 Mo 2 O 9 (LM) ionic conductor and the conventional Solid Oxide Fuel Cell (SOFC) cathode material La 0.8 Sr 0.2 MnO 3-d (LSM), was probed using secondary ion mass spectrometry (SIMS), and diffusion coefficients of Sr, Mo and Mn cations within both materials evaluated. Diffusion coefficients extracted from samples with a Sr solution deposited on the LM pellets and from a Mo solution deposited on LSM pellets were found to be orders of magnitude higher than the cross-diffusion through the inter-face between two dense pellets in direct contact. These differences may be due to uncertainty in determining the interface position, or to a real dependence on the source of the diffusing cation. In the most favorable case, that of pellets in direct contact, extrapolation of diffusion coefficients down to a typical SOFC operating temperature, 800 8C, show that Mo diffusion in LSM (diffusion coefficient~10 À14 cm 2 .s À1 ) is much higher than Sr or Mn diffusion in LM, and incompatible with use in a SOFC device, unless an efficient buffer layer is used.[a] Dr.

show abstract

Innovative solid oxide fuel cells based on BaIn0.3Ti0.7O2.85 electrolyte and La2Mo2O9 amorphous reduced phase as anode material

Cited by 13 publications

References 24 publications

Direct Observation of Oxide Ion Dynamics in La₂Mo₂O₉ on the Nanosecond Timescale

Direct Observation of Oxide Ion Dynamics in La₂Mo₂O₉ on the Nanosecond Timescale

Reduction Kinetics of La₂Mo₂O₉ and Phase Evolution during Reduction and Reoxidation

Cationic Interdiffusion at the SOFC Electrolyte/Cathode Interface in La₂Mo₂O₉/La_0.8Sr_0.2MnO_3‐δ

Contact Info

Product

Resources

About

Innovative solid oxide fuel cells based on BaIn0.3Ti0.7O2.85 electrolyte and La2Mo2O9 amorphous reduced phase as anode material

Cited by 13 publications

References 24 publications

Direct Observation of Oxide Ion Dynamics in La2Mo2O9 on the Nanosecond Timescale

Direct Observation of Oxide Ion Dynamics in La2Mo2O9 on the Nanosecond Timescale

Reduction Kinetics of La2Mo2O9 and Phase Evolution during Reduction and Reoxidation

Cationic Interdiffusion at the SOFC Electrolyte/Cathode Interface in La2Mo2O9/La0.8Sr0.2MnO3‐δ

Contact Info

Product

Resources

About

Direct Observation of Oxide Ion Dynamics in La₂Mo₂O₉ on the Nanosecond Timescale

Direct Observation of Oxide Ion Dynamics in La₂Mo₂O₉ on the Nanosecond Timescale

Reduction Kinetics of La₂Mo₂O₉ and Phase Evolution during Reduction and Reoxidation

Cationic Interdiffusion at the SOFC Electrolyte/Cathode Interface in La₂Mo₂O₉/La_0.8Sr_0.2MnO_3‐δ