Ag-GDC复合电极的性能及其在直接碳SOFC中的应用

制备了Ag与Gd掺杂的氧化铈(GDC)复合的电极材料。采用氧化钇稳定的氧化锆(YSZ)为电解质,Ag-GDC为阴极和阳极,组装成固体氧化物燃料电池(SOFC),采用担载5%(质量分数)Fe的活性炭为SOFC的燃料,对此直接碳SOFC(DC-SOFC)的输出性能及阻抗谱进行测试,并与采用传统阴极(掺Sr的锰酸镧与YSZ的复合材料)的DC-SOFC性能进行了比较,发现Ag-GDC具有更好的性能。采用扫描电镜(SEM)对电池的微观结构进行了分析,并就其对电池性能的影响进行了分析。     

管式电解质支撑型直接碳固体氧化物燃料电池的浸渍法制备及电性能

管状电解质支撑型固体氧化物燃料电池(SOFC)具有稳定性高、电极选择范围广、易封接等优点,很适合应用于直接碳固体氧化物燃料电池(DC-SOFC)现阶段的基础研究中。为实现管状电解质支撑型SOFC的便捷制备,本研究开发了管状YSZ(钇稳定化氧化锆)电解质支撑膜的浸渍法制备工艺。组装了电极材料为Ag-GDC(钆掺杂氧化铈)的电解质支撑型SOFC单电池。测试了单电池分别以加湿氢气和担载5%(w,质量分数)Fe的活性炭为燃料,环境空气为氧化剂的电性能。电池的开路电压接近理论值,且扫描电镜分析结果表明电解质膜致密。单电池以活性碳为燃料在800°C取得了280 m W?cm~(-2)的最大功率密度,接近其以加湿氢气为燃料的330 m W?cm~(-2)。交流阻抗谱结果表明YSZ电解质的欧姆电阻是影响电池性能的主要原因。DC-SOFC以恒电流1 A放电,运行了2.1 h,燃料利用率为36%。DC-SOFC二次装载碳燃料后的电性能几乎与初次的性能一样,表明制备的YSZ电解质支撑膜可稳定的应用于DC-SOFCs中。分析了DC-SOFC放电过程中电性能衰减的机制。     

质子导体固体氧化物燃料电池的Ba_2Co_9O_(14)阴极材料

Ba2Co9O14(BCO)是一种新型的电子-氧离子混合导体,在氧离子导体的固体氧化物燃料电池(SOFC)中,其作为阴极材料的应用可能性已经得到证实,本工作探索BCO在质子导体SOFC中的应用可能性。采用固相反应法制备BCO粉体,研究BCO与质子导体电解质BZCY(Ba Zr0.1Ce0.7Y0.2O3-δ)之间的化学相容性,分析BCO-BZCY复合阴极在BZCY电解质上的电化学性能。当复合阴极中BCO的质量含量为70%时,阴极性能最佳,界面阻抗活化能为1.26 e V。以BCO-BZCY为阴极,Ni-BZCY为阳极,BZCY为电解质的阳极支撑型单电池,700℃时,单电池的极化阻抗为0.15Ω·cm2,最大功率密度为400 m W·cm-2。     

固体氧化物燃料电池电化学阻抗谱差异化研究方法和分解

电化学阻抗谱技术(EIS)在固体氧化物燃料电池(SOFC)中已获得广泛应用。在EIS分析过程中,研究者能够清楚地获得燃料电池内部因纯离子(电子)导电引起的欧姆电阻和因电化学过程、扩散作用引起的极化阻抗的大小,但是对于极化阻抗的构成缺乏进一步解析。本文选用传统的Ni-YSZ阳极支撑电池,通过改变测试温度、阳极运行气氛和阴极运行气氛,设计了一套完整的阻抗差异分析(ADIS)实验。并基于弛豫时间分布法(DRT)和阻抗差异分析法,系统地分析并解释了阻抗谱中各频率段对应阻抗的物理或(电)化学含义,将该类型电池阻抗谱以6个RQ并联电路予以拟合,为之后燃料电池性能稳定性的研究奠定基础。     

以活性炭为燃料的固体氧化物燃料电池(英文)

采用注浆成型法制备了管状电解质支撑的固体氧化物燃料电池(SOFC),电解质材料为YSZ,阳极和阴极材料都采用银.将活性炭不加任何气体直接用作电池的燃料.电池的有效面积为2.5cm2,在800℃时给出最大功率为16mW,其开路电压随温度的变化与理论结果一致.此电池在30mA的恒电流下连续稳定运行了37h,通过电化学反应消耗了加入电池中碳燃料的42%(w),证明了电池的工作是可以自维持的.与使用石墨燃料的SOFC相比,此电池的运行稳定性得到了明显的提高,因为活性炭比石墨具有大得多的微孔率和表面积.电池运行37h后很快衰减,燃料烧结和燃料量减少造成碳表面积减小可能是衰减的主要原因.电化学阻抗谱测试结果表明电池的极化电阻在电池的总损耗中占主导.通过对电池反应机理进行分析,认为发生在阳极/电解质界面的CO电化学氧化反应和发生在碳燃料表面的Boudouard反应构成的循环维持了电池的运行,因此通过添加促进上述两个反应的催化剂,可提高电池的性能.     

一种高活性 Ni掺杂 La0.6Sr0.4FeO3-δ作为碳基燃料固体氧化物燃料电池对称电极

固体氧化物燃料电池(SOFCs)是一种在中高温下可以直接将储存在燃料中的化学能转换成电能的全固态电化学反应装置.因其具有能量转换效率高、环境友好、全固态结构以及可以使用碳氢化合物燃料等优点,近年来受到了广泛的关注.在诸多电极材料当中, Ni基金属陶瓷是 SOFCs中最常使用的阳极材料,这是由于金属 Ni具有优良的电子电导和催化性能.然而当使用碳基化合物燃料时,传统的 Ni金属陶瓷阳极材料面临严重的积碳、Ni颗粒长大以及硫中毒等问题.这些问题不仅会影响 SOFCs的寿命,而且还会严重地降低 SOFC的商业化进程.因此,开发具有高催化活性、抗积碳的阳极材料对碳氢化合物为燃料的固体氧化物燃料电池的发展至关重要.与金属基阳极相比,氧化物阳极的热膨胀系数与电解质材料更匹配,性能的可调控性更强.铁酸锶镧(LSF)是一种分子式为 ABO3的钙钛矿结构的氧化物,在高温下具有较高的电子电导率.据报道 LSF作为阴极材料时,表现出了良好的性能.但是 LSF作为阳极材料时,却存在着催化性能不足的问题.我们研究了 Ni掺杂的 La0.6Sr0.4FeO3-δ(LSFN),以提高其作为 SOFCs阳极材料的催化性能.同时采用将 LSFN在 SOFC工作气氛下原位还原的方法,在 LSFN颗粒表面原位生长出分布均匀的纳米颗粒.透射电镜分析结果表明该偏析的颗粒为 Ni-Fe合金.有报道显示, Ni-Fe合金对碳氢化合物氧化具有良好的催化活性,所以在 LSFN颗粒表面生成这种合金颗粒有利于提高阳极材料的催化活性.对于 Ni-Fe合金以均匀的纳米颗粒析出的原因,还有待进一步研究.为了研究 LSFN作为 SOFC电极材料的性能,我们采用浸渍法将 LSFN前驱体溶液浸渍到氧化钇稳定氧化锆(YSZ)一体化电池的对称多孔骨架中,经过焙烧,得到了具有对称结构的 SOFC单电池.所使用的 YSZ一体化骨架为中间层薄而致密,两边厚而多孔的三层结构,这种结构可以显著地降低电解质的厚度,从而达到降低单电池的阻抗的目的.这一新型对称电池结构具有如下优点：阳极表面上可能发生的硫毒化和积碳问题有可能通过将阳极和阴极反用而消除;氧化剂(空气)将冲走吸附在电极上的硫和碳粒子,从而使电极得以再生.此外,氧化还原稳定的阴极预期将提高阴极的寿命.对单电池的电化学测试结果表明, LSFN电极材料的最佳浸渍量为30 wt%,这是因为较低的 LSFN浸渍量(<30 wt%),不能形成连续的电子传导网络,电极的电子传导能力不足;而 LSFN电极材料的浸渍量高于30 wt%时则会降低电极反应的三相界面,从而影响电池的性能.在750oC下, LSFN为电极的单电池在以湿润 C3H8为燃料时其开路电压(OCV)达到了约1.18 V,高于以 H2为燃料电池的电压.以 CH4为燃料时, LSFN为电极的单电池的开路电压远高于 LSF为电极的单电池.在750oC下,以 C3H8为燃料时, LSFN和 LSF为电极的电池的峰值输出功率密度分别达到400和230 mW/cm2.这些结果表明,通过 Ni掺杂和原位焙烧,在 LSFN电极颗粒表面制备了均匀分布的 Ni-Fe合金纳米颗粒,极大地提高了铁酸锶镧材料对碳基燃料的催化活性.长期放电测试结果表明, LSF为电极的单电池在测试过程中,尾气可以收集到类似焦油状的黑色物质;而 LSNF为电极的单电池在测试过程中并没有观察到明显的焦油状物质生成.通过气相色谱-质谱联用分析,发现所产生的焦油状物质主要成分是含苯环、碳碳双建或碳碳三键的烃类.这说明 LSF电极只能使 C3H8部分氧化, LSFN对 C3H8等碳氢化合物燃料的氧化具有高的催化活性和良好的耐久性. Ni掺杂的 La0.6Sr0.4FeO3-δ阳极材料是一种有希望的碳基燃料 SOFCs对称电极.     

固体氧化物燃料电池直接以焦炭为燃料的电性能

直接碳固体氧化物燃料电池（DC-SOFC）是一种潜在的固体碳燃料高效率、低污染发电技术。本研究报道了将工业焦炭直接用作管式DC-SOFC燃料的研究。制备了电极材料为Ag-GDC （钆掺杂氧化铈）的YSZ （钇稳定化氧化锆）电解质支撑型管式固体氧化物燃料电池（SOFC）。采用拉曼光谱、扫描电镜和X射线能谱仪对焦炭燃料进行了性质表征。结果表明,焦炭燃料呈微米级的颗粒状,并含有大量对Boudouard反应有利的缺陷结构。电池以纯焦炭为燃料在850℃取得的最大功率密度为149mW/cm²,在碳燃料表面负载能提高Boudouard反应速率的Fe催化剂后,最大功率密度提高至217mW/cm²。通过电化学测试和尾气表征,分析了恒电流放电过程中电池的性能衰减机制。测试结果证明了将焦炭直接用作全固态DC-SOFC的燃料产生电能的可行性。     

固体氧化物燃料电池直接以焦炭为燃料的电性能（英文）

直接碳固体氧化物燃料电池(DC-SOFC)是一种潜在的固体碳燃料高效率、低污染发电技术。本研究报道了将工业焦炭直接用作管式DC-SOFC燃料的研究。制备了电极材料为Ag-GDC(钆掺杂氧化铈)的YSZ(钇稳定化氧化锆)电解质支撑型管式固体氧化物燃料电池(SOFC)。采用拉曼光谱、扫描电镜和X射线能谱仪对焦炭燃料进行了性质表征。结果表明,焦炭燃料呈微米级的颗粒状,并含有大量对Boudouard反应有利的缺陷结构。电池以纯焦炭为燃料在850℃取得的最大功率密度为149 mW/cm~2,在碳燃料表面负载能提高Boudouard反应速率的Fe催化剂后,最大功率密度提高至217 mW/cm~2。通过电化学测试和尾气表征,分析了恒电流放电过程中电池的性能衰减机制。测试结果证明了将焦炭直接用作全固态DCSOFC的燃料产生电能的可行性。     

双过渡层阴极对流延法制备的阳极支撑直接碳固体氧化物燃料电池性能的改善作用

采用流延法制备了阳极支撑的固体氧化物燃料电池(SOFC),电解质材料为钇稳定化氧化锆(YSZ),阳极为镍和YSZ构成的金属陶瓷(Ni-YSZ),阴极为LSCF-GDC/LSCF复合材料,同时在阴极与电解质之间制备了YSZ-GDC/GDC双过渡层。分别采用含3%的加湿H_2和活性炭为燃料,对此电池的输出性能及阻抗谱进行测试。采用加湿H_2测试的结果表明:在800℃下,采用双过渡层电池的开路电压达到1 V,最大功率密度为680 mW·cm~(-2),比未改良电池的最大功率密度(372 mW·cm~(-2))提高了83%。直接采用固体碳为燃料时,具有双过渡层阴极的电池在850℃时的开路电压达到0.95 V,最大输出功率密度达429 mW·cm~(-2),几乎比无过渡层阴极的电池(225 mW·cm~(-2))高出1倍,特别是双过渡层阴极还使直接使用碳燃料的SOFC(DC-SOFC)的燃料利用率提高了33%。     

一种高活性Ni掺杂La_(0.6)Sr_(0.4)FeO_(3-δ)作为碳基燃料固体氧化物燃料电池对称电极（英文）

固体氧化物燃料电池(SOFCs)是一种在中高温下可以直接将储存在燃料中的化学能转换成电能的全固态电化学反应装置.因其具有能量转换效率高、环境友好、全固态结构以及可以使用碳氢化合物燃料等优点,近年来受到了广泛的关注.在诸多电极材料当中,Ni基金属陶瓷是SOFCs中最常使用的阳极材料,这是由于金属Ni具有优良的电子电导和催化性能.然而当使用碳基化合物燃料时,传统的Ni金属陶瓷阳极材料面临严重的积碳、Ni颗粒长大以及硫中毒等问题.这些问题不仅会影响SOFCs的寿命,而且还会严重地降低SOFC的商业化进程.因此,开发具有高催化活性、抗积碳的阳极材料对碳氢化合物为燃料的固体氧化物燃料电池的发展至关重要.与金属基阳极相比,氧化物阳极的热膨胀系数与电解质材料更匹配,性能的可调控性更强.铁酸锶镧(LSF)是一种分子式为ABO_3的钙钛矿结构的氧化物,在高温下具有较高的电子电导率.据报道LSF作为阴极材料时,表现出了良好的性能.但是LSF作为阳极材料时,却存在着催化性能不足的问题.我们研究了Ni掺杂的La_(0.6)Sr_(0.4)FeO_(3-δ)(LSFN),以提高其作为SOFCs阳极材料的催化性能.同时采用将LSFN在SOFC工作气氛下原位还原的方法,在LSFN颗粒表面原位生长出分布均匀的纳米颗粒.透射电镜分析结果表明该偏析的颗粒为Ni-Fe合金.有报道显示,Ni-Fe合金对碳氢化合物氧化具有良好的催化活性,所以在LSFN颗粒表面生成这种合金颗粒有利于提高阳极材料的催化活性.对于Ni-Fe合金以均匀的纳米颗粒析出的原因,还有待进一步研究.为了研究LSFN作为SOFC电极材料的性能,我们采用浸渍法将LSFN前驱体溶液浸渍到氧化钇稳定氧化锆(YSZ)一体化电池的对称多孔骨架中,经过焙烧,得到了具有对称结构的SOFC单电池.所使用的YSZ一体化骨架为中间层薄而致密,两边厚而多孔的三层结构,这种结构可以显著地降低电解质的厚度,从而达到降低单电池的阻抗的目的.这一新型对称电池结构具有如下优点:阳极表面上可能发生的硫毒化和积碳问题有可能通过将阳极和阴极反用而消除;氧化剂(空气)将冲走吸附在电极上的硫和碳粒子,从而使电极得以再生.此外,氧化还原稳定的阴极预期将提高阴极的寿命.对单电池的电化学测试结果表明,LSFN电极材料的最佳浸渍量为30wt%,这是因为较低的LSFN浸渍量((27)30wt%),不能形成连续的电子传导网络,电极的电子传导能力不足;而LSFN电极材料的浸渍量高于30wt%时则会降低电极反应的三相界面,从而影响电池的性能.在750oC下,LSFN为电极的单电池在以湿润C_3H_8为燃料时其开路电压(OCV)达到了约1.18V,高于以H_2为燃料电池的电压.以CH_4为燃料时,LSFN为电极的单电池的开路电压远高于LSF为电极的单电池.在750oC下,以C_3H_8为燃料时,LSFN和LSF为电极的电池的峰值输出功率密度分别达到400和230mW/cm~2.这些结果表明,通过Ni掺杂和原位焙烧,在LSFN电极颗粒表面制备了均匀分布的Ni-Fe合金纳米颗粒,极大地提高了铁酸锶镧材料对碳基燃料的催化活性.长期放电测试结果表明,LSF为电极的单电池在测试过程中,尾气可以收集到类似焦油状的黑色物质;而LSNF为电极的单电池在测试过程中并没有观察到明显的焦油状物质生成.通过气相色谱-质谱联用分析,发现所产生的焦油状物质主要成分是含苯环、碳碳双建或碳碳三键的烃类.这说明LSF电极只能使C_3H_8部分氧化,LSFN对C_3H_8等碳氢化合物燃料的氧化具有高的催化活性和良好的耐久性.Ni掺杂的La_(0.6)Sr_(0.4)FeO_(3-δ)阳极材料是一种有希望的碳基燃料SOFCs对称电极.     

Electrode materials and reaction mechanisms in solid oxide fuel cells: a brief review. III. Recent trends and selected methodological aspects

Continuing previous reviews on mixed-conducting electrodes for intermediate-temperature solid oxide fuel cells (IT SOFCs), this work presents a short overview of novel cathode and anode materials, their electrochemical performance in contact with oxygen anion- and proton-conducting solid electrolytes, and specific features determining possible applications. Priority was given mainly to recent research reports published during the last 2–5 years. Particular emphasis is focused on the relevant methodological aspects, potential limitations and drawbacks, and factors affecting electrode polarization and durability. Typical ranges of the polarization resistances, overpotentials, power densities in the cells with various current collectors, and the electrode materials total conductivity and thermal expansion are compared. The electrode compositions appraised in single-chamber and micro-SOFCs, hydrocarbon- and carbon-fueled cells, high-temperature electrolyzers, and other solid-electrolyte appliances are briefly covered in light of their similarity to the common SOFC materials discussed in the previous parts.     

Electrode materials and reaction mechanisms in solid oxide fuel cells: a brief review

This work is focused on the comparative analysis of electrochemical and transport properties in the major families of cathode and anode compositions for intermediate-temperature solid oxide fuel cells (SOFCs) and materials science-related factors affecting electrode performance. The first part presents a brief overview of the electrochemical and chemical reactions in SOFCs, specific rate-determining steps of the electrode processes, solid oxide electrolyte ceramics, and effects of partial oxygen ionic and electronic conductivities in the SOFC components. The aspects associated with materials compatibility, thermal expansion, stability, and electrocatalytic behavior are also briefly discussed. Primary attention is centered on the experimental data and approaches reported during the last 10–15 years, reflecting the main challenges in the field of materials development for the ceramic fuel cells.     

A novel multistep dip-coating method for the fabrication of anode-supported microtubular solid oxide fuel cells

A novel multistep dip-coating method was developed and successfully applied to the fabrication of anode-supported microtubular solid oxide fuel cells (SOFCs) using carbon rods as combustible cores. The fabricated microtubular SOFCs consisted of Ni-yttria-stabilized zirconia (YSZ), YSZ, strontium-doped lanthanum manganite (LSM)–YSZ, and LSM as the anode, electrolyte, cathode, and cathode current collector materials, respectively. To investigate the role of anode porosity on cell performance, two types of anode supports were prepared: one without a pore former and the other with a 10 wt.% graphite pore former. The microstructural features of the microtubular SOFCs were examined using scanning electron microscope images whereas the electrochemical performance was characterized by electrochemical impedance spectroscopy measurements as well as I–V characteristic curves. The results showed that the method used is a simple and low-cost alternative to conventional methods for the fabrication of microtubular SOFCs. We found that the anode porosity played an important role in improving the overall performance of the microtubular SOFC by reducing the concentration polarization.     

阳极负载型SOFC阳极基底厚度对性能的影响

制备不同厚度阳极负载型YSZ薄膜固体氧化物燃料电池 ,并对电池的极化、放电性能进行了测试 .结果表明 ,电池的性能明显受阳极性能的影响 ,阳极过电位大的原因之一是受多孔阳极气体扩散的影响 .降低阳极基底的厚度 ,阳极过电位明显减小 ,电池性能明显提高 .当阳极基底厚度为 0 .5mm时 ,在 80 0℃工作温度下 ,电池的功率密度达到 0 .1 9W·cm- 2 ,较之阳极厚度为 1 .0mm的电池性能提高近 1 .5倍 (0 .1 3W·cm- 2 ) .     

A verification of the reaction mechanism of direct carbon solid oxide fuel cells

Anode-supported tubular solid oxide fuel cells (SOFCs) with Cu–CeO₂–yttria-stabilized zirconia (YSZ) anode, YSZ electrolyte film, and silver cathode were fabricated. The cells were tested with 5 wt% Fe-loaded activated carbon and dry CO, respectively, and their performances were compared to verify the reaction mechanism of direct carbon SOFCs (DC-SOFCs). The corresponding current–voltage curves and impedance characteristics of the cells operating on these two different fuels were found to be almost the same at high temperatures, demonstrating the presumed mechanism that the anode reaction of a DC-SOFC is the electrochemical oxidation of CO, just as in a SOFC operated directly on CO. Some experimental evidences including the difference in open circuit voltage at different temperatures and the operating stability of the cells were analyzed in detail.     

Correlation of the electrochemical reversibility and resolution of the anode and cathode peaks of the electrode processes of hydroquinone and metol on graphite and platinum

Cyclic and direct voltammetry with linear potential sweep was used to study the potential difference of the anode and cathode peaks for hydroquinone and metol in the cyclic voltammograms (CVA) of their individual solutions on the main factors affecting the reversibility of the electrochemical process on electrodes of a graphite-epoxy composite (GEC), namely, the state of the surface of the indicator electrode, the pH of the buffer solution, and the mode of polarization. The surface state of the GEC electrode was affected by its passivation in air for various periods of time; the reversibility of the electrode process was judged by the difference between the anode and cathode potentials on the CVAs of hydroquinone and metol. A correlation was found between the degree of reversibility and the difference of peak potentials for similar electrode processes of hydroquinone and metol on the GEC electrode and other solid electrodes made of graphite materials and platinum.     

Effect of pretreatments on the anode structure of solid oxide fuel cells

An important objective in the development of solid oxide fuel cell (SOFC) is to produce thin stabilized zirconia electrolytes that are supported upon the nickel–zirconia composite anode. Although this will reduce some of the problems associated with SOFCs by permitting lower temperature operation, this design may encounter problems during start- up. The first step in a start-up involves the reduction of nickel oxide in the anode to metallic nickel and increase of three-phase boundary will be beneficial for further reaction. In this study, two pretreatment methods are investigated for their effects on the performances of SOFC. Performances of the SOFCs are influenced by the pretreatment conditions, which included exposure of the cells to dilute H₂/O₂ either under open-circuit or closed-circuit conditions before their performance studies. By carrying out the methods, the pretreatment using the closed circuit is found to attain much higher performances effectively and efficiently. Accompanying with SEM and element analysis, increase of three-phase boundary is considered to give rise to changes in the anode microstructure, leading to activation of the anode. Mechanisms of NiO in anode reducing to Ni and porous structure via different pretreatments and their effects on the anode microstructure are proposed.     

Single solid-oxide fuel cells with supporting ni-cermet anode

Single solid-oxide fuel cells (SOFCs) with a porous (36-41%) supporting Ni-cermet anode are manufactured and tested. The effect of the thickness of the supporting Ni-cermet anode on the electrochemical characteristics of single SOFCs is studied. It is shown that polarization losses on electrodes at the current density of 1.2 A/cm² increase by about 2 times from 0.13 to 0.25 V at an increase in the thickness of the supporting Ni-cermet anode from 0.40 to 1.27 mm. The impedance spectroscopy method is used to identify relaxation processes responsible for the behavior of the fuel cell anode and cathode. It is found that a significant percentage of polarization losses on the anode is due to transport limitations in fuel supply to the three-phase nickel/electrolyte/gas phase interface and removal of the reaction products away from it.