中温固体氧化物燃料电池电解质材料及其制备工艺的研究发展趋势

RESEARCH AND DEVELOPMENT TRENDS OF ELECTROLYTE MATERIALS AND TECHNOLOGY IN INTERMEDIATE TEMPERATURE SOLID OXIDE FUEL CELL

综合介绍了中温固体氧化物燃料电池(solid oxide fuel cells,SOFCs)的电解质材料以及薄膜的制备工艺。中温SOFCs的工作温度应低于800℃,甚至低于750℃,为600～800℃。固体氧化物电解质的晶体结构基本上属于下列两类:面心立方的萤石型和立方型钙钛矿晶体结构。稳定ZrO2是萤石型结构电解质的一个典型代表。8%(摩尔分数,下同)氧化钇稳定氧化锆(8% in mole Y2O3 stabilized ZrO2,8YSZ),其在1000℃左右才有可观的离子电导率(0.1S/cm)。在800℃,氧化钪掺杂氧化锆(Zr0.9Sc0.1O1.95,scandia doped zirconia,SSZ)的电导率(0.1S/cm)比Zr0.9Y0.1O1.95(10YSZ)的(0.03S/cm)高得多。Sm掺杂的CeO2(samarium doped ceria,CSO)电解质有希望应用于中温SOFCs。Sr和Mg掺杂LaGaO3(LSGM)氧离子导体已成为中低温SOFCs重要候选电解质材料。改进氧化锆基电解质的电导性能的另一个途径是薄膜化。厚度小于10μm的YSZ基SOFCs,在800℃,0.8V时的功率密度可达800mW/cm2。薄膜比厚膜能提供更好的化学均匀性和更易控制成分。SOFCs要求精细和尺度小时,通常选择薄膜;而低成本和大尺寸时,通常选择厚膜。成本较低的膜成型工艺有等离子喷涂、胶态成型工艺、流延成型、冷冻干燥成型、丝网印刷和真空泥浆浇注等。

The electrolyte materials used in intermediate temperature solid oxide fuel cells （SOFCs） are reviewed, and the fabrication processes of film components are introduced emphatically in this paper. The operation temperature of intermediate temperature SOFCs must be lower than 800 ℃, even lower than 750 ℃, with a temperature range of 600-800℃. Good solid oxide electrolytes belong to generally two crystallographic families, namely face-centered fluorite and primitive cubic perovskite structures. A representative of fluorite solid electrolytes is the stabilized ZrO2. 8% in mole Y2O3 stabilized ZrO2 （8YSZ） has a considerable ionic conductivity of 0.1S/cm at ~1 000℃. Zr0.9Sc0.1O1.95 （SSZ） has a conductivity of 0.1 S/cm at 800℃ whereas Zr0.9Y0.1O1.95 （herein after referred to YSZ）） has a conductivity of 0.03 S/cm at the same temperature. Samarium doped ceria （CSO） is a desired electrolyte material for use of intermediate temperature SOFCs. Sr and Mg doped LaGaO3（LSGM） oxygen ion conductor already is a important alternator for intermediate and low temperature SOFCs. Another way to lower the operating temperature ofa SOFC is the use of thin elec- trolyte membranes. At 800℃ YSZ thin film with a thickness less than 10 μm ceils demonstrated excellent performance, achieving power densities of 800 mW/cm2 at 0.8 V. Generally, thin films provide higher chemical homogeneity and composition control than thick films. Thin films are preferred in precise and laboratory scale applications, while thick film techniques are preferred for low-cost and up-scalable manufacturing. Film fabrication techniques for low-cost include plasma spray, colloidal state forming, tape casting method, freeze-drying process, screen printing and vacuum slip casting etc.