构型熵工程增强双钙钛矿型氧电极抗 Cr 中毒能力

Solid oxide fuel cells (SOFCs) are a kind of highly efficient and clean power generation devices whose cathode performance is critically important for the commercial application of the entire cell. Cation segregation on the surface of cathodes significantly affects the performance and operational stability. The double perovskite oxide PrBa_0.8Ca_0.2Co₂O_5+δ (PBCC), a highly active cathode, still suffers from serious surface segregation and insufficient Cr-tolerance ability. In order to improve the stability of cathode, an A-site medium-entropy double perovskite oxide Pr_0.6La_0.1Nd_0.1Sm_0.1Gd_0.1Ba_0.8Ca_0.2Co₂O_5+δ (ME-PBCC) derived from PBCC was prepared, and its segregation behavior in Cr-containing atmosphere was systematically investigated. Compared with traditional PBCC cathode, segregation of BaCrO₄ and Co₃O₄ on the surface of ME-PBCC is significantly suppressed, which is attributed to its higher configurational entropy. Electrical conductivity relaxation (ECR) and electrochemical impedance spectroscopy (EIS) results indicate that electrochemical stability of the ME-PBCC cathode has been significantly improved. Among the improvements, after Cr deposition for 48 h, the oxygen surface exchange coefficient k_chem of the medium-entropy cathode decreases from 4.4×10^–4 cm·s^–1 to 1.8×10^–4 cm·s^–1, with the reduction of k_chem significantly lower than that of PBCC (which decreases from 7.3×10^–4 cm·s^–1 to 1.2×10^–4 cm·s^–1). Furthermore, the EIS results after treatment in Cr-containing air at 700 ℃ for 48 h show that the polarization resistance (R_p) of ME-PBCC is only 0.07 Ω·cm², which is lower than 0.11 Ω·cm² of PBCC, confirming that the medium-entropy cathode has significantly improved operational stability and Cr resistance. This study demonstrates that ME-PBCC is a promising cathode material for SOFCs.