【作者】 李艳华；

【导师】 刘晓梅；

【作者基本信息】 吉林大学 ， 凝聚态物理， 2004， 硕士

【摘要】 燃料电池是一种高效、低污染的能量转化装置，之所以称其为电池，是因为同其它化学电池一样，都是由阴极、阳极和电解质组成。但它又不同于一般意义上的电池，一般意义上的电池是一种储能装置，而燃料电池却是一种能量转化装置，用于转化电能的化学能来自燃料和氧化剂气体的反应能，从这一意义上讲，燃料电池也可以看作是一种靠电化学过程发电的　“发电 53<WP=60>机”。但燃料电池不同于传统的热机，一般的发电机都要通过热机转换，其发电效率受到卡若循环的限制，而燃料电池不受卡诺循环的限制；另外，燃料电池一般采用气体燃料，粉尘和有害气体排放量很小。因此,燃料电池将在未来能源发展中占有重要地位。 固体氧化物燃料电池（简称 ＳＯＦＣ）作为第四代燃料电池，有几点优越性是很直接的：它具有全固态结构，操作方便，避免了使用液态电解质所带来的腐蚀和电解质流失等问题；燃料广泛，不仅可以使用 Ｈ２、ＣＯ 等燃料，而且可以直接使用天然气、煤气以及其它碳氢化合物；无需贵金属作催化剂，大大降低了电池的成本；考虑热电联供，能量综合利用率可以达到 ８０％以上。因此，ＳＯＦＣ 的发展更是备受关注。　 传统的 ＳＯＦＣ 一般以 ８％ｍｏｌ 的钇稳定氧化锆（ＹＳＺ）作为电解质，掺锶的锰酸镧（ＬＳＭ）为阴极，　Ｎｉ／　ＹＳＺ 金属陶瓷为阳极，但必须在高温条件下才能具有较高的离子电导率，而高温操作增加了材料选择和制备上的困难。因此降低电池的操作温度，寻求中温区新型的电解质和与之相匹配的电极材料成为新世纪推 ＳＯＦＣ 实用化的关键任务之一。基于此，本文在研究中温电解质 Ｃｅ１－ｘＳｍｘＯ２－δ（ｘ＝０．０５，０．１，０．１５，０．２，０．３）的制备条件和性能的基础上，采用优选配比的原则，利用固相法制备了 ＮｉＯ／ＳＤＣ 复合阳极材料，并对其性能（电导率，过电位等）进行了研究和讨论：　 （１）用 Ｓｏｌ－Ｇｅｌ 法制备了 Ｃｅ１－ｘＳｍｘＯ２－δ（ｘ＝０．０５，０．１，０．１５，０．２，０．３）系列电解质材料，通过对它们的晶体结构、电导率以及热膨胀等一系列的性能测试，详细比较并讨论了它们的电导率、氧离子空位的产生以及热膨胀等微观机制的异同。测试结果表明溶胶－凝胶法制备的 Ｃｅ１－ｘＳｍｘＯ２－δ（ｘ＝０．０５～　０．３）系列电解 １３００℃即可形成高致密度的立方萤石结构，此温度远低于传统的高温固相法烧结温度：１６００℃－１６５０℃；　Ｃｅ０．８５Ｓｍ０．１５Ｏ２－δ配比的样品，其交流阻抗谱，热膨胀系数均表现出优于其它配比合成的样品的性质，８００℃时的电导率为 2<WP=61>０．０９２Ｓ／ｃｍ，　导电活化能为 ０．７４２　ｅＶ。　 （２）优选Ｃｅ０．８５Ｓｍ０．１５Ｏ２－δ电解质，利用机械混合法制备了 ＮｉＯ／ＳＤＣ 系列复合阳极材料，通过对样品的 ＸＲＤ 谱分析表明，　还原前样品的主要成分为 ＳＤＣ相　和 ＮｉＯ 相，还原后样品的主要成分为 ＳＤＣ 相和 Ｎｉ 相，说明 ＮｉＯ 还原后已变成了金属 Ｎｉ；其电化学性能测试和交流阻抗谱测试表明，样品在还原前后，导电机制发生了明显的变化，还原前均为离子与电子－空穴导电相结合的混和导体，还原后表现为良好的电子导电性，阳极材料的电导率很大程度上取决于 Ｎｉ 的含量，导电率与 Ｎｉ 含量的关系呈 Ｓ 形趋势，根据渗透理论可以解释为复合阳极材料中存在两种导电机制，即穿过 Ｎｉ 相的电子导电通道和穿过 ＳＤＣ 相的离子导电通道。总之，NiO/SDC 系列复合阳极材料的性能指标在Ni质量比为 ６０％时出现极值。更多还原

【Abstract】 Fuel cells are a device which can convert energy with high efficiency andlow pollution. They are also called cells because they are composed of cathode、anode and electrolyte sandwiched by them, which are the same with thetraditional cell, But they produce electricity by electrochemical combination offuel gas (e.g. hydrogen) with oxidant gas (e.g. oxygen),which differs from thetraditional cell used to reserve energy. So they can also be looked as a generatorwith an electrochemical process. But compared with the conventional generatorwhose efficiency of producing electricity, they are not subject to the Carnot 3<WP=62>limitation, they convert the chemical energy directly to electrical energy withoutintermediate of thermal energy and have excellent energy conversionefficiency as a result. In addition to high efficiency and low emissions, they havealso several other advantages such as modular and distributed nature, and muchlower production of pollutants. Since fuel cells just have these advantages, theywill play an essential role in any future hydrogen fuel economy. As the forthgeneration fuel cell, SOFCs (Solid Oxide Fuel Cells)hasseveral outstanding advantages: Because all the components of SOFCs ar e solid,they can be fabricated in very thin layers and configured into uni- que shapesunachievable in other fuel cells systems having a liquid electr- olyte. Thesefeature permit themdesign with additionalperformance imp- rovement;moreover, SOFCs offer good fuel flexibility, they can use the H2, CO as well asthe natural gas﹑ coal gas turns spirit and other carbon hydrogencompounds asfuel materials. During SOFC operating, they are unnecessary to use preciousmetals as the catalyst, so the cost of them can be minimized, the efficiency of theoverallenergyconversion efficiency can attain 80% above. the development of SOFCs attractsthe interests all over the world because of these merits. Today’s demonstration SOFCs utilize yttria stabilized zirconia(YSZ)containing typically mol%Y, as the electrolyte; a ceramic-mentalcomposite(cermet) comprised of Ni+YSZ as the anode; and La1-xSrxMnO3-δ,(lanthanum strontium manganite or LSM)as the cathode，in general, they mustoperate at high temperature because of the low ionic conductivity of YSZelectrolyte at lower operating temperatures, such high operating temperaturescause many serious problems such as physical and chemical degradation of the 4<WP=63>SOFCs component materials. Therefore, it is important to reduce the operationtemperature of SOFCs, it is desirable to develop the new electrolyte operating atthe Intermediate-Temperature(IT) and the electrode materials which match with itmutually. According to these, in this thesis, bases on study of synthesis andperformance of Ce1-xSmxO2-δ(x=0.05，0.1，0.15，0.2，0.3),we adopted the meansof optimization to go together with ratio, the NiO/SDC composite anodematerials were synthesized by using the traditional method. The properties of thesynthesized products were studied in detail using XRD spectra﹑　a.c. impedancespectra and electrochemical analysis: (1) A series of Ce1-xSmxO2-δ(x=0.05，0.1，0.15，0.2，0.3) electrolyte weresynthesized by Sol-Gel method. By the measurements of their physical propertiessuch as crystal structure﹑　a.c. impedance spectra and thermal expansion, theirdifferences in micro-mechanism were compared and discussed. The results of theresearch show that Ce1-xSmxO2-δ(x=0.05～0.3) electrolyte are single phase solidsolutions with fluorite structure at 1300℃，which is much lower than thetemperature of using solid state method:　1600℃-1650℃；moreover,　Ｃｅ０．８５Ｓｍ０．１５Ｏ２－δ　has the highest conductivity of 0.092S/cm and the lowest activation energy of0.742 eV at 800℃. (2) Several NiO/SDC composite anode with different NiO contents weresynthesized by mechanic更多还原