电化学极化原位生成含钴阴极与电解质之间界面的机理

Solid oxide fuel cells (SOFC) are a highly efficient and environment-friendly electrochemical power generation device. It is essential to develop intermediate temperature SOFC (IT-SOFC) and utilization of high performance cobaltite cathode materials is vital to enhance the output performance of IT-SOFC. Based on applicants’ preliminary original study on in situ fabrication of cobaltite cathodes at SOFC’s operating temperatures, the aim of this project is to unravel the mechanism of in situ electrode/electrolyte formation of cobaltite cathodes induced by electrochemical polarization. The project contains the following several parts. (1) Investigating the effects of key factors such as conductivity of electrolyte, electrocatalytic activity, ionic conductivity, microstructure of cobaltite cathodes, level and direction of polarization current, and duration of polarization on the formation of electrode/electrolyte interface, so as to unravel the mechanism and kinetics of electrochemical polarization induced interface formation; (2) Surveying the electrode processes and rate-determining steps of oxygen reduction reaction (ORR) on cobaltite cathodes prepared via the electrochemical polarization, in order to understand the effect of in situ formation of interface on the mechanism of ORR; and (3) Examining the potential change of polarization formed interface as well as structure, composition and electrocatalytic performance of cobaltite cathodes, so as to clarify the evolution mechanism of electrode/electrolyte interface. The success of this project will provide insights into fundamental and technological understanding of in situ formation and evolution of electrode/electrolyte interface induced by the electrochemical polarization, fostering direct application of cobaltite cathodes on barrier-layer-free zirconia electrolyte.

固体氧化物燃料电池（SOFC）是一种高效、环保的电化学发电装置。中温化是SOFC发展的必然趋势，而应用高性能含钴阴极是提高中温区电池输出性能的重要途径。本项目基于申请人在电池运行温区原位制备含钴阴极的前期原创性研究结果，致力于阐明电化学极化引致含钴阴极层与电解质之间的界面生成机理。拟开展以下几方面的工作：（1）研究电解质电导率、阴极催化性能、离子导电性、微结构、极化电流、电流方向、极化时间等关键因素对界面生成的影响，阐明电化学极化生成界面的机理和动力学过程；（2）探究电化学极化法制备的含钴阴极的氧还原过程和反应速度控制步骤，揭示极化生成的界面对于阴极反应机理的影响；（3）考察极化生成的界面和阴极结构、组成、电化学性能的变化规律，构建界面的演化机理。本项目的完成，有望获得电化学极化引致界面原位生成和演化机理和技术关键，为在氧化锆电解质上直接构筑含钴阴极提供理论和实践依据。

本项目提出了电化学极化法制备免烧含钴阴极的新思路，避免了传统的高温烧结过程，简化了阴极制备流程，同时保留了阴极初始粉体的精细微结构，提升了阴极的电化学催化活性。通过研究电化学极化法构筑免烧含钴阴极/电解质界面的关键影响因素，掌握了该方法构筑免烧电极/电解质界面的机制和技术关键；通过解析阴极的内阻组成，揭示了经电化学极化法构筑的免烧阴极氧还原反应机理和速度控制步骤；通过开展长时间稳定性测试，验证了长期运行后电化学极化法制备的阴极仍保留初始精细微结构，从而确保免烧电极的运行稳定性。项目成功地解决了免烧含钴阴极/电解质界面构筑的关键科学问题，进而推进电化学极化法制备免烧含钴阴极工程问题的解决。在Electrochemical Energy Reviews、Applied Catalysis B: Environmental、Chemical Engineering Journal等期刊发表SCI论文14篇、核心期刊论文2篇、授权发明专利6件（含转让1件）、培养硕士研究生3名。

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