Compositional and configuration entropy tuning enabling Cr-resistance cathodes for solid oxide fuel cells

The performance and stability of solid oxide fuel cell (SOFC) cathodes are severely limited by chromium poisoning. To address these concerns, we designed and investigated A-site two high-entropy perovskite oxides, which possess equivalent configuration entropy but distinct elemental compositions. Compared to the conventional double perovskite PrBaCo₂O_5+δ (PBC), the PBSLSC cathode demonstrated superior oxygen reduction reaction activity, while PBSNGC showed inferior performance. Crucially, both high-entropy cathodes exhibited significantly enhanced resistance to chromium poisoning, as evidenced by the suppressed formation of SrCrO₄ and Co₃O₄ secondary phases. This improved Cr-tolerance is due to high-entropy sluggish diffusion effect, which mitigates the segregation of Ba/Sr and cobalt elements. Our findings demonstrate that while configurational entropy is critical, the specific elemental composition is a decisive factor in determining cathode activity. This work establishes high-entropy engineering as a powerful strategy for developing highly active and Cr-tolerant cathodes for intermediate-temperature SOFCs.