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Tailoring thermal expansion characteristic of SrFe_1-xTi_xO_3-δ cathodes through Ti doping for intermediate-temperature solid oxide fuel cell application
Ili-Mastura Mashudi, Afifah Z. Juri and Nurul Akidah Baharuddin

This study investigates the thermal expansion behavior of SrFe_1-xTi_xO_3-δ (SFT) cobalt-free cathode materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs). SFT cathodes with varying titanium dopant concentrations (x = 0.1-0.5) were synthesized via the glycine-nitrate combustion method. Increasing x effectively reduced the SFT cathode thermal expansion coefficient (TEC), approaching that of the SDC electrolyte. While lower TEC is generally favored, it was observed that increasing x correlated with increased area-specific resistance (ASR) from previous work, suggesting that factors beyond TEC mismatch influence electrochemical performance. Notably, the SF9T1 composition (x = 0.1), despite exhibiting the highest TEC among the SFT series, demonstrated the best electrochemical performance and good adhesion to the electrolyte, highlighting its potential as promising IT-SOFC cathode material. The observed TEC differences compared to prior reports emphasize the influence of the synthesis method. This work provides valuable insights into the complex relationship between dopant concentration, TEC, ASR, and interfacial compatibility in SFT cathodes for IT-SOFC applications.

Keywords: Solid oxide fuel cell, cobalt-free cathode, thermal expansion coefficient, delamination, microstructural