固体氧化物燃料电池(SOFC)合金连接体耐高温氧化导电防护涂层

降低固体氧化物燃料电池(SOFC)工作温度,可使用高电导、高热导、高强度的合金作为连接体。其中含Cr的铁素体不锈钢合金,具有与SOFC其他部件材料匹配的热膨胀系数,此外还有易于加工及成本低廉等优点,成为中低温板式SOFC连接体材料应用与研究的重点。但这类合金表面高温氧化所带来的界面电阻变化,及Cr挥发进而在阴极沉积所带来的诸多问题,成为影响板式SOFC长期稳定的关键因素,因此必须进行有效的表面处理。从SOFC合金连接体引起的电堆性能衰减机理出发,阐明了降低或防止阴极Cr中毒的几类方法,论述了合金连接体涂层的必要性。结合笔者开发设计的尖晶石粉末还原法在合金连接体表面制备纳米微结构Mn_(0.9)Y_(0.1)Co_2O_4(MYC)防护涂层方面的工作,综述了国内外SOFC合金连接体涂层材料及涂层制备方法的研究进展。对各类涂层材料及涂层制备方法优缺点进行比较的同时,重点介绍了电导率高、实用性较强的钙钛矿结构及尖晶石结构涂层材料。最后展望了合金连接体涂层的发展前景。

Conductive Protective Coating with Heat Oxygen-resistance for Solid Oxide Fuel Cell (SOFC) Alloy Interconnect

The alloy with high conductivity, thermal conductance and strength can be used as the interconnect to reduce the temperature of solid oxide fuel cell (SOFC). The chromium-containing ferritic stainless steels are selected as the leading candidate alloys in the application and study of interconnects for intermediate and low temperature SOFC due to thermal coefficient of expansion matching with the component material of SOFC, easy processing, low cost, etc.. However, issues caused from both interface resistance change induced from surface high-temperature oxidation, and the Cr volatilization and deposition to the cathode, have become the major reasons to influence the long-term stability of SOFC. Therefore, effective surface treatment must be carried out. Based on the degradation mechanism induced from alloy interconnect of SOFC stack, the work illustrates several methods to reduce or prevent cathode Cr poisoning and summarizes that it is necessary to prepare a protective coating on the surface of interconnect alloy. In combination with the previous study by the authors about the Mn0.9Y0.1Co2O4 (MYC) protective coating of nanostructure on alloy interconnect prepared by the spinel powders reduction technique, the domestic and overseas development of coating materials and fabrication methods for SOFC alloy interconnect are elaborately reviewed. For comparison of the advantages and disadvantages of all kinds of coating materials and coating preparation methods, the perovskite structure and spinel structure materials are highlighted due to high electrical conductivity and practical application ability. Finally, the outlook of alloy interconnect coating is outlined.