Jinghe Bai,Zhiying Han,Defeng Zhou,Xiaofei Zhu,Ning Wang,Ruyi Chen,Jing He,Wenfu Yan
As a Ruddlesden-Popper (RP) phase solid oxide fuel cell (SOFC) cathode material , Pr 2 NiO 4+δ (PNO) is a critical challenge for SOFC commercialization due to the lack of oxygen vacancies and insufficient redox reaction (ORR) activity. In this paper, various concentrations of La 0.6 Sr 0.4 CoO 3-δ (LSC) nanoparticles are coated on the surface of PNO by an impregnation method, and the ORR kinetics of PNO is found to be improved by constructing a composite cathode with heterointerfaces. The formation of the heterointerface effectively enhances the transfer of interstitial oxygen in the PNO and the oxygen vacancies in LSC, which can promote the conduction of O 2− in the cathode and thus improves the ORR activity of the material. When the impregnation concentration of LSC reached C LSC = 0.2 mol L −1 , the ORR activity can reach the highest level. At 700 °C, the area-specific resistance of PNO-LSC reaches 0.024 Ω cm 2 , which is 83.4% lower than that of PNO (0.145 Ω cm 2 ). And the peak power density of PNO-LSC reaches 0.618 W cm −2 , which is 1.89 times larger than that of PNO (0.327 W cm −2 ). Therefore, the construction of composite cathodes with heterointerfaces via impregnation provides an alternative strategy for enhancing the ORR activity of the cathode materials in SOFC.
Yihui Liu,Kai Kang,Zhuofei Pan,Chao Wang,Kangtao Jiang,Yun Wang
Pr 2 NiO 4+δ -based (Ruddlesden-Popper) perovskite-structured oxide materials are promising candidates for low and intermediate temperature solid oxide fuel cells (SOFCs) systems. In this study, we prepared a high-performance cubic-fluorite/perovskite heterostructure Pr 6 O 11 -Pr 1.2 Sr 0.8 NiO 4+δ (PO-PSNO) cathode for intermediate temperature SOFCs by solution impregnation method. By changing the impregnation amount of Pr 6 O 11 , the micro-morphology of the heterostructure was regulated, so that the heterostructure interface had the best reactive site. The oxygen reduction reaction (ORR) performance of Pr 1.2 Sr 0.8 NiO 4+δ is improved, and the content of surface Sr in the heterostructure electrode material is reduced. Our results indicate that the synergistic effect of PO particles and PSNO skeleton makes the heterostructure exhibit a high oxygen surface exchange properties and catalytic performance. When the impregnation amount of PO particles reaches about 10% of the PSNO skeleton, the heterostructure has the best ORR activity. The oxygen surface exchange coefficient (K chem ) of 2-PO-PSNO is 5.8 × 10 -4 cm·s −1 , being 1.45 times as that of PSNO at 750 °C. Meanwhile, the polarization impedance (R p ) of 2-PO-PSNO is reduced by 66% to only 0.114 Ω cm 2 . Our study provides a new approach for developing high-performance RP structured perovskite cathodes and demonstrates practical applications in the field of SOFCs.
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.
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