化学学报 ›› 2024, Vol. 82 ›› Issue (1): 36-45.DOI: 10.6023/A23090412 上一篇    下一篇

研究论文

氟掺杂对可逆固体氧化物电池性能的影响及相关动力学研究

李萍a,b, 杨琪玉a, 曾婧a, 张然a, 陈秋燕a, 闫飞a,b,*()   

  1. a华北电力大学(保定) 环境科学与工程系 河北 保定 071003
    b河北省燃煤电站烟气多污染物协同控制重点实验室 华北电力大学(保定) 河北 保定 071003
  • 投稿日期:2023-09-13 发布日期:2023-11-29
  • 基金资助:
    项目受国家自然科学基金(52102246); 中央高校基本科研业务费专项资金(2023MS144); 中央高校基本科研业务费专项资金(2023MS149)

Effect of Fluorine Doping on the Performance of Reversible Solid Oxide Cells and Related Kinetic Studies

Ping Lia,b, Qiyu Yanga, Jing Zenga, Ran Zhanga, Qiuyan Chena, Fei Yana,b()   

  1. aDepartment of Environmental Science and Engineering, North China Electric Power University, Baoding Campus, Baoding 071003, Hebei, China
    bNorth China Electric Power University, Baoding Campus, Hebei Key Laboratory of Power Plant Flue Gas Multi-Pollutants Control, Baoding 071003, Hebei, China
  • Received:2023-09-13 Published:2023-11-29
  • Contact: E-mail: yanfeiican@tju.edu.cn
  • Supported by:
    National Natural Science Foundation of China(52102246); Fundamental Research Funds for the Central Universities(2023MS144); Fundamental Research Funds for the Central Universities(2023MS149)

可逆固体氧化物电池(RSOC)表现出优异的热力学和动力学性质, 被认为是一种很有前途的能量转换装置. 制备了两种RSOC电极材料La0.6Sr0.4Fe0.8Co0.2O3 (LSFC)和La0.6Sr0.4Fe0.8Co0.2F0.1O2.9 (F0.1-LSFC), 对比了F掺杂对电池放电和电解性能的影响并对电极表面动力学反应进行探究. 研究表明F掺杂可降低B位元素价态、提高材料氧空位浓度, 进而提高电池性能. 700 ℃, 30%H2O/H2燃料下, 由F0.1-LSFC组成的RSOC的最大功率密度为234.3 mW•cm-2, 约为LSFC组成的RSOC的1.7倍. 并且在1.3 V下, 由LSFC和F0.1-LSFC组成的RSOC的电流密度分别为–245.6和–417.9 mA•cm-2. 此外, 通过电极表面动力学分析发现, 对于氢氧化反应(HOR), F0.1-LSFC电极反应的速度控制步骤(RDS)主要是电荷转移反应, 而LSFC电极反应的RDS主要是氢气的吸附和解离反应; 对于氧还原反应(ORR), RDS是吸附的氧原子还原成O-.

关键词: 可逆固体氧化物电池, 镧锶铁钙钛矿, 氢氧化反应, 氧还原反应, 电化学性能

Reversible solid oxide cell (RSOC) exhibits excellent thermodynamic and kinetic properties and is considered as a promising energy conversion device. In this work, two types of RSOC electrode materials, La0.6Sr0.4Fe0.8Co0.2O3 (LSFC) and La0.6Sr0.4Fe0.8Co0.2F0.1O2.9(F0.1-LSFC) are synthesized using the solid-state reaction method, the effects of fluorine doping on the cell discharge and electrolysis performance are discussed. Meanwhile, the electrode surface kinetic reactions are also explored through construction of equivalent symmetrical cells. After fluorine doping, SrF2 precipitates in F0.1-LSFC material, resulting in defects in perovskite La sites, which further leads to Coulomb cation exclusion and lattice disorder of FeO6 octahedron, resulting in expansion of unit cell volume. Moreover, the results also show that fluorine doping can reduce the valence state of B-site elements, increase the concentration of oxygen vacancies, and thereby improve cell performance. The maximum power density of RSOC composed of F0.1-LSFC at 700 ℃ with 30%H2O/H2 as the fuel is 234.3 mW•cm-2, approximately 1.7 times higher than that of RSOC composed of LSFC. And at 1.3 V, the current densities of the RSOC composed of LSFC and F0.1-LSFC are –245.6 and –417.9 mA•cm-2, respectively. The effect of fluorine doping on the catalytic activity of perovskite materials for hydrogen oxidation reaction (HOR) is investigated. The results show that the catalytic activity of perovskite materials for HOR can be improved by fluorine doping. In addition, the electrochemical impedance spectra (EIS) under different hydrogen partial pressures were measured by adjusting the hydrogen partial pressure (pH2) on both sides of the equivalent symmetrical cells, so as to explore the rate determining step (RDS) of electrode reaction. The results show that the RDS of electrode reaction changes after fluorine doping. For LSFC electrode, the RDS of reaction is mainly hydrogen adsorption and dissociation reaction, while for F0.1-LSFC electrode, the RDS of reaction is mainly charge transfer reaction. Similarly, the test method of equivalent symmetrical cells is still used for oxygen reduction reaction (ORR) dynamics research. The difference is that the atmosphere on both sides of the cells becomes O2. From EIS test results, it can be seen that with the increase of temperature, the polarization resistance (RP) value of the equivalent symmetrical cell gradually decreases, and the RP value of F0.1-LSFC is lower than LSFC, indicating that fluorine doping and increasing the operating temperature can reduce the RP value, thereby improving the catalytic activity of ORR. It is worth noting that the RP value of the equivalent symmetrical cell composed of LSFC and F0.1-LSFC in O2atmosphere is lower than that in H2 atmosphere, indicating that LSFC and F0.1-LSFC electrode materials are more prone to ORR. On the other hand, the RDS of ORR process can be studied from the effect of oxygen partial pressure (pO2) on EIS of equivalent symmetrical cells. The results show that the RDS of electrode for ORR process is the reduction of oxygen atoms to O-.

Key words: reversible solid oxide cell, LaSrFeO3 perovskite oxide, hydrogen oxidation reaction, oxygen reduction reaction, electrochemical performance