Enhancing Stability and Performance of Pr2NiO4+δ Cathode Materials for SOFCs through Low-Strontium Doping

In this study, Pr 2-x Sr x NiO 4+δ (x = 0.1, 0.15, 0.2) cathode materials are synthesized via the EDTA-citric acid method, and the effects of low-strontium doping on their crystal structure, phase stability, and electrochemical performance are systematically evaluated. The results show that at a low Sr 2+ doping level, the material maintains the original K 2 NiF 4 -type structure. The results indicate that low-concentration Sr 2+ doping caused no significant change to the crystal structure of the material, while the samples with x=0.15 and x=0.2 maintain relatively good thermal stability at elevated temperatures. Meanwhile, the low content of Sr 2+ can reduce the loss of interstitial oxygen in the cathode material, this balance greatly improves the high-temperature electrical conductivity and electrocatalytic activity. The area specific resistance values of Pr 1.9 Sr 0.1 NiO 4 , Pr 1.85 Sr 0.15 NiO 4 , Pr 1.8 Sr 0.2 NiO 4 at 800 °C are 0.042 Ω cm 2 , 0.027 Ω cm 2 and 0.065 Ω cm 2 , respectively. Another crucial finding is that the maximum power densities of Pr 2-x Sr x NiO 4+δ (x = 0.1, 0.15, 0.2) in the single cells at 800 °C are 505, 598, and 310 mW cm 2 , respectively. In addition, the average thermal expansion coefficient of Pr 2-x Sr x NiO 4+δ ranges from 14.1 to 15.1×10 -6 K -1 between 30 and 1000 °C, closely matching that of conventional electrolytes. These results indicate that Pr 2-x Sr x NiO 4+δ (x = 0, 0.1, 0.15, 0.2) is a promising cathode material for solid oxide fuel cells. This work presents a research framework for optimizing Pr 2 NiO 4+δ cathodes, highlighting that low-level Sr 2+ doping balances stability and activity—both critical attributes for fuel cell materials.