Suppressing Elemental Segregation in Yttrium-Doped Barium Zirconate Proton-Conducting Electrolytes via Crystal Defect Engineering

Proton-conducting ceramic cells (PCCs) are pivotal for advanced clean energy conversion devices due to their high proton conductivity and outstanding fuel flexibility. However, the fabrication of electrolytes remains a critical challenge in PCC, particularly for chemically stable yet refractory BaZr0.85Y0.15O3−δ (BZY), which suffers from severe elemental evaporation and phase segregation during high-temperature sintering. Herein, we propose a defect engineering strategy for fabricating high-quality electrolytes by suppressing rapid cationic migration along defect channels. Low-defect BZY crystals are successfully fabricated by the molten salt synthesis (MSS) method, exhibiting a 51% reduction in lattice distortion rate compared to conventional combustion-derived samples. The electrolyte sintered from BZY-MSS powder achieves chemical homogeneity, effectively eliminating the occurrence of detrimental impurity segregation. The assembled fuel cell demonstrates a significantly higher conductivity compared with the conventional BZY-based cells. This work validates crystal defect engineering as an effective strategy for resolving the persistent fabrication bottlenecks in proton-conducting electrolytes.