The molten salt synthesis of core-shell heterostructure cathode materials for solid oxide fuel cells
Embargo Date
2023-08-26
OA Version
Citation
Abstract
Solid oxide fuel cells (SOFCs) are high temperature electrochemical energy conversion devices that convert chemical energy directly to electricity. Several technical and cost drivers exist to lower the operating temperature of SOFCs from the state-of-the-art 1000˚C to less than 800˚C. However, one of the main hurdles for SOFCs becoming commercially viable is the sluggish reaction kinetics of the oxygen reduction reaction (ORR) at the cathode as the operating temperature is reduced. La0.6Sr0.4Co0.2Fe0.8O3-∂ (LSCF) perovskite is a state-of-the-art cathode material, yet it suffers from low surface catalytic activity for the ORR. One way to mitigate this shortcoming has been to infiltrate nanoparticle electrocatalysts, such as La0.8Sr0.2MnO3-∂ (LSM) perovskite onto the surface of LSCF. However, infiltration often requires multiple rounds to achieve uniform coverage of the substrate, numerous chemical agents for optimization, and additional decomposition and calcination steps. These pitfalls can be eliminated by instead using a molten salt to synthesize core-shell heterostructures. In this work, the molten salt synthesis (MSS) is investigated as a potential method to synthesize core-shell LSCF-LSM SOFC cathodes. The influence of multiple molten salt chemistries on the successful synthesis of LSM and stability of LSCF is studied and a thermodynamic rationale is determined. The MSS of core-shell LSCF-LSM nanoparticles is demonstrated for the first time and parameters are explored to maximize core-shell yield. Core-shell heterostructure cathodes are then fabricated and their performances are characterized using electrochemical impedance spectroscopy (EIS).