GDC粉体的制备优化及其作为SOFC单电池阻挡层的应用研究

发布时间：2018-02-21 06:17

  本文关键词： SOFC GDC 阻挡层 水系流延 烧结助剂　出处：《景德镇陶瓷学院》2014年硕士论文　论文类型：学位论文

【摘要】：在过去20年里，固体氧化物燃料电池(Solid oxide fuel cell，SOFC）的研究取得了不菲的成果。传统SOFC的工作温度较高，会导致其电池寿命短和制造成本高等一系列问题，因此提高电极的催化性能、降低电池的工作温度日趋成为研究重点。混合离子-电子导体LSCF比纯电子导体LSM（传统的阴极材料）对O2具有更高的催化活性，将其作为阴极的单电池在中低温下拥有更高的放电性能。但是LSCF与传统电解质YSZ（Y2O3稳定的ZrO2）发生反应生成的低电导相会影响电池性能，且与YSZ热匹配性差，经多次热循环后易分层影响电池寿命。本课题主要围绕制备与电极和电解质有良好的匹配性和化学相容性的GDC阻挡层而展开研究。 本文分别采用尿素和NH4HCO3作沉淀剂制备GDC（10mol%Gd2O3掺杂CeO2）纳米粉体，通过对比这两种粉体的形貌及其烧结体的烧结性能和电性能，得出NH4HCO3作沉淀剂合成的GDC更适合制备致密度高且氧离子导电性能好的阻挡层。通过对比分析陈化温度、陈化时间、反应温度、洗涤方式等对GDC粒径和团聚性的影响，得出符合阻挡层要求的GDC粉体的制备工艺为：在60℃恒温水浴锅内，向已配好的0.1mol/L的Gd和Ce的硝酸盐溶液中，边搅拌边按一定的速度逐滴加入NH4HCO3沉淀剂，直至溶液pH＞7。加料完全后的体系在80℃下陈化6小时，再将得到的乳白色沉淀，用去离子水和无水乙醇分别离心洗涤3次后置于70℃烘箱中烘干，最后在空气气氛下750℃煅烧保温2h，获得分散性良好且尺寸分布较均应的GDC粉体。 助烧结剂Bi2O3的添加，可有效地降低GDC的烧结温度，，使之在1280℃时便可烧结致密，从而阻止了高温共烧时GDC与YSZ间的反应。样品相对密度随着助烧结剂Bi2O3添加量的增加而增大，在3%的Bi2O3添加量下GDC的相对密度达最大值。GDC的电导率与其致密度变化一致，当含量为3%时电导率达最大值0.05388S/cm。这主要是由于样品越致密越利于氧空位的迁移，电导率自然也就升高。 在相同条件下（700℃下，以3%H2O+H2为燃料，空气为氧化气体），添加GDC阻挡层的单电池的极化电阻和欧姆电阻分别为1.13Ωcm2和0.45Ωcm2，均远小于未添加GDC层的单电池。这是因为阻挡层有效地避免了阴极和电解质之间的反应，阻止高阻抗物质Sr2ZrO4或La2Zr2O7的生成，使得电池性能得以提升。添加了阻挡层的单电池最大功率密度可达0.70W/cm2，而未添加GDC阻挡层的单电池最大功率密度仅为0.24W/cm2。
[Abstract]:In the past 20 years, solid oxide fuel cells (SOFCs) have achieved remarkable results. The high working temperature of traditional SOFC leads to a series of problems, such as short battery life and high manufacturing cost, so the catalytic performance of the electrodes is improved. Reducing the working temperature of the battery is becoming the focus of the research. The mixed ion-electronic conductor LSCF has higher catalytic activity to O2 than the pure electronic conductor LSM (traditional cathode material). However, the low conductance phase formed by the reaction of LSCF with the traditional electrolyte YSZ(Y2O3 stabilized ZrO2 will affect the performance of the cell, and its thermal compatibility with YSZ is poor. It is easy to delaminate the battery life after repeated thermal cycles. This paper focuses on the preparation of GDC barrier layer with good matching and chemical compatibility with electrodes and electrolytes. In this paper, urea and NH4HCO3 were used as precipitators to prepare GDC(10mol%Gd2O3 doped CEO _ 2 nano-powders. The morphology, sintering properties and electrical properties of the two kinds of powders were compared. It is concluded that GDC synthesized with NH4HCO3 as precipitant is more suitable for the preparation of barrier layers with high density and good oxygen ion conductivity. The effects of aging temperature, aging time, reaction temperature and washing method on the particle size and agglomeration of GDC are compared and analyzed. The preparation process of GDC powder which meets the requirements of barrier layer is obtained as follows: in 60 鈩

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