A Novel Self‐Assembled Cobalt‐Free Perovskite Composite Cathode with Triple‐Conduction for Intermediate Proton‐Conducting Solid Oxide Fuel Cells

A traditional composite cathode for proton‐conducting solid oxide fuel cells (H‐SOFCs) is typically obtained by mixing cathode materials and proton conducting electrolyte of BaCe 0.7 Y 0.2 Zr 0.1 O 3–δ (BZCY), providing chemical and thermal compatibility with the electrolyte. Here, a series of triple‐conducing and cobalt‐free iron‐based perovskites as cathodes for H‐SOFCs is reported. Specifically, BaCe x Fe 1– x O 3–δ ( x  = 0.36, 0.43, and 0.50) shows various contents of two single phase perovskites with an in situ heterojunction structure as well as triple conductivity by tailoring the Ce/Fe ratios. The cell performance with the optimized BaCe 0.36 Fe 0.64 O 3–δ (BCF36) cathode composition reaches 1056 mW cm −2 at 700 °C. Moreover, a record cell performance of 1525 mW cm −2 at 700 °C is obtained by modifying the BCF36 cathode microstructure through a spraying method, demonstrating high promise with Co‐free cathodes for H‐SOFCs.