Gd掺杂的CeO2纳米粉体及阻挡层的制备与物性研究

Abstract

Gd doped CeO2（CGO）is one of the most attentive electrolyte materials, which could reduce the operation temperature of solid oxide fuel cells (SOFCs) to intermediate temperature (600℃~800℃). In this paper, Acrylic acid modified sol-gel method is employed to prepare nanoscale Ce0.8Gd0.2O2-δ and Ce0.85Gd0.15O2-δ powders，PVP or PEG is used as dispersant to solve the agglomeration of CGO powders. The CGO powders prepared exhibited a narrow particle size distribution，the average particle size is ca.20nm，the BET special area surface of Ce0.8Gd0.2O2-δ and Ce0.85Gd0.15O2-δ powders could reach 56.69m2g-1 and 62.18m2g-1 respectively. The CGO powders exhibited a high sintering activity, the wafer prepared by squash method and sintered at 1350 ha℃s the highest densification, and the relative density could reach 95%. The conductivity of Ce0.8Gd0.2O2-δ and Ce0.85Gd0.15O2-δ powders is 0.024S cm-1 and 0.011S cm-1 respectively. The anode-supported SOFC using Ni-YSZ as anode, YSZ as electrolyte, LSCF-CGO as cathode need an interlayer to prevent the reaction between YSZ electrolyte and LSCF cathode. In this paper, CGO interlayer is obtained by spray coating method, the influence of CGO powders pre-sintering temperature, addition of PVP, planetary milling process and sintering temperature on the structural properties is studied systematically. The optimized preparation condition is CGO powders pre-sintered at 750℃，planetary ball milling for 48h by Φ2mm ball, 6wt%PVP added and sintering temperature of above 1250℃, which can prevent the interfacial reaction between YSZ electrolyte and LSCF cathode efficiently. The single cell with CGO interlayer sintered above 1250℃ exhibited area special ohmic resistance (ASR) of below 0.192Ωcm2 at 850 and average maximum power density ℃of above 600mW cm-2 at 750.℃Gd掺杂的CeO2（CGO）是目前最受关注的电解质材料之一，CGO电解质可以将固体氧化物燃料电池的运行温度降低到中低温（500℃~800℃）。本文用丙烯酸改进的溶胶凝胶法制备纳米Ce0.8Gd0.2O2-δ和Ce0.85Gd0.15O2-δ粉末，通过加入分散剂PVP或PEG解决CGO粉体的团聚问题。该法制备的Ce0.8Gd0.2O2-δ和Ce0.85Gd0.15O2-δ粉体的粒径约为20nm，颗粒分布均一，比表面积分别高达56.69m2g-1和62.18 m2 g-1。粉体烧结活性较高，用压片法制备的该粉体的圆片在1350℃下烧结达到最高的致密度，相对致密度达到95%。在650℃下Ce0.8Gd0.2O2-δ和Ce0.85Gd0.15O2-δ的电导率分别为0.024S cm-1和0.011 S cm-1。 对Ni-YSZ为阳极支撑、YSZ为电解质、LSCF-CGO为复合阴极的单电池，需要在YSZ电解质和LSCF阴极之间制备一层阻挡层。本文研究了湿法喷涂制备CGO阻挡层过程，考察了粉体预处理温度、PVP用量、行星球磨和烧结温度对CGO阻挡层结构和性能的影响。实验证明CGO阻挡层的最佳制备条件为：粉体预处理温度为750℃、Φ2mm的氧化锆球球磨48h、PVP用量为6wt%、烧结温度为1250℃~1300℃。制备的CGO阻挡层能够成功地阻挡YSZ电解质和LSCF阴极的反应。在850℃下，单电池欧姆电阻小于0.192Ω cm2；在750℃下，单电池的最大功率密度高于600 mW cm-2