Double Perovskite Sr<sub>2</sub>CoFeO<sub>5+</sub><sub>δ</sub>: Preparation and Performance as Cathode Material for Intermediate-temperature Solid Oxide Fuel Cells
Zhengpeng Chen, Fangjun Jin, Mingfei Li, Jiangbo Dong, Renci Xu, Hanzhao Xu, Kai Xiong, Muming Rao, Chuangting Chen, Xiaowei Li, Yihan Ling
Abstract
As the operating temperature decreases, intermediate-temperature solid oxide fuel cells (IT-SOFCs) require cathode materials with high catalytic activity.In this study, double perovskite Sr2CoFeO5+δ (SCF) was synthesized by Sol-Gel method, and the effect of different ratios of SCF cathode compounded with 20% (molar fraction) Sm2O3 doped CeO2 (SDC) on the electrode performance was elucidated.The SOFC single-cell performance was improved by the optimized chemical expansion and area-specific resistance (ASR) from composite electrodes.Results show that, the good chemical compatibility with common electrolytes can be observed from the SCF cathode after annealing at 950 ℃ for 10 h, and the average thermal expansion coefficient (TEC) of pure SCF can be significantly reduced for the composite sample of SCF and SDC at a mass ratio of 1:1, from 2.44×10 -5 to 1.54×10 -5 K -1 .ASR of SCF-xSDC (SDC content: 20%, 30%, 40%, 50%(in mass)) composite cathodes were as low as 0.036, 0.034, 0.028 and 0.092 Ω•cm 2 at 800 ℃, respectively.The SCF-40SDC composite cathode exhibited the lowest ASR value in the whole temperature range.Based on the 0.3 mm-thick La0.9Sr0.1Ga0.8Mg0.2O3-δ(LSGM) electrolyte, the maximum power density of SOFC using SCF-40SDC (757 mW• cm -2 ) as a cathode is higher than that of SCF (684 mW• cm -2 ).These results demonstrate that the SCF-40SDC composite cathode is a promising candidate for application in IT-SOFCs.