Visualizing the structural evolution of LSM/xYSZ composite cathodes for SOFC by in-situ neutron diffraction

Area of Science:

• Materials Science
• Electrochemistry
• Solid State Chemistry

Background:

• Composite cathodes are crucial for solid oxide fuel cell (SOFC) performance.
• Understanding thermal stability and reaction mechanisms in cathode materials is essential for SOFC longevity.
• Lanthanum strontium manganite (LSM) and yttria-stabilized zirconia (YSZ) are common SOFC cathode components.

Purpose of the Study:

• To determine the thermal stability of LSM-YSZ composite cathodes.
• To visualize phase evolution and analyze ion diffusion in heterogeneous cathode systems at high temperatures.
• To elucidate the reaction mechanism and kinetics between LSM and YSZ.

Main Methods:

• In-situ neutron diffraction was employed to study composite cathodes.
• High flux neutron source enabled visualization of phase evolutions.
• Structural analysis was used to derive ion diffusion activities.

Main Results:

• Tetragonal-to-cubic phase transition in YSZ above 900°C caused Mn ion redistribution.
• LSM and YSZ reaction at >1100°C occurred in a three-stage kinetic process.
• La2Zr2O7, SrZrO3, and MnO were identified as reaction products.

Conclusions:

• The thermal stability of LSM-YSZ cathodes is governed by phase transitions and ion diffusion.
• The three-stage reaction mechanism is strongly correlated with Y, Mn, and La ion behavior at elevated temperatures.
• In-situ neutron diffraction provides critical insights into high-temperature reaction kinetics in composite materials.