Controlling Interfacial Cation Interdiffusion to Unlock the Intrinsic Performance of Pr-Based PCFC Cathodes
Year: 2026
Type: preprint
Abstract: Bridging the gap between the intrinsic electrocatalytic activity of cathode materials and their practical performance in proton-conducting fuel cells (PCFCs) requires a fundamental understanding of cation interdiffusion at the electrode-electrolyte interface. In this study, we investigate the cation diffusion and adhesion ability for Pr-based perovskite cathodes of Pr 0.5 Sr 0.5 Co 0.75 Fe 0.25 O 3−δ (PSCF), PrBaCo 1.5 Fe 0.5 O 5+δ (PBCF), and Ba/Sr co-doped PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.5 O 5+δ (PBSCF) on a BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3−δ (BZCYYb) electrolyte. X-ray diffraction analysis reveals that conventional 1000 °C adhesion process triggers irreversible cation interdiffusion across the interface, resulting in a severe lattice expansion in PSCF and PBCF of +0.5 % and +1.3 %, respectively, leading to the delamination of the cathode from the electrolyte. To eliminate these interfacial penalties and evaluate the intrinsic electrocatalytic activity, a 750 °C bonding process was employed. By suppressing this cation interdiffusion, the irreversible volume variations were constrained to approximately ±0.1%, achieving crack-free interfaces for all compositions. Evaluated under these ideal conditions, the Sr-substituted simple perovskite PSCF demonstrated the highest peak power density, exceeding the benchmark PBSCF. This performance fundamentally originates from its disordered framework (Pnma), which provides enhanced electron-donating capability, an enriched concentration of surface-active oxygen intermediates, and superior electrical conductivity for rapid bulk charge transfer during the oxygen reduction reaction. Our thermomechanical analysis also reveals that the Ba/Sr co-doped PBSCF uniquely utilizes interfacial cation interdiffusion to counterbalance contact-induced expansion, maintaining a continuous interface even at 1000 °C. This study establishes a dual strategy for advancing PCFCs: unlocking the intrinsic electrocatalytic potential of active cathodes by either suppressing interfacial cation mixing via low-temperature processing or utilizing it through interface-tailored A-site engineering for spontaneous strain neutralization.
Source: ChemRxiv
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7204997503