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Fabrication and characterization of anode-supported micro-tubular solide oxide fuel cell by phase inversion method.

机译：相转化法制备阳极支撑微管固体氧化物燃料电池及表征。

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摘要

Nowadays, the micro-tubular solid oxide fuel cells (MT-SOFCs), especially the anode supported MT-SOFCs have been extensively developed to be applied for SOFC stacks designation, which can be potentially used for portable power sources and vehicle power supply. To prepare MT-SOFCs with high electrochemical performance, one of the main strategies is to optimize the microstructure of the anode support. Recently, a novel phase inversion method has been applied to prepare the anode support with a unique asymmetrical microstructure, which can improve the electrochemical performance of the MT-SOFCs. Since several process parameters of the phase inversion method can influence the pore formation mechanism and final microstructure, it is essential and necessary to systematically investigate the relationship between phase inversion process parameters and final microstructure of the anode supports. The objective of this study is aiming at correlating the process parameters and microstructure and further preparing MT-SOFCs with enhanced electrochemical performance.;Non-solvent, which is used to trigger the phase separation process, can significantly influence the microstructure of the anode support fabricated by phase inversion method. To investigate the mechanism of non-solvent affecting the microstructure, water and ethanol/water mixture were selected for the NiO-YSZ anode supports fabrication. The presence of ethanol in non-solvent can inhibit the growth of the finger-like pores in the tubes. With the increasing of the ethanol concentration in the non-solvent, a relatively dense layer can be observed both in the outside and inside of the tubes. The mechanism of pores growth and morphology obtained by using non-solvent with high concentration ethanol was explained based on the inter-diffusivity between solvent and non-solvent. Solvent and non-solvent pair with larger Dm value is benefit for the growth of finger-like pores. Three cells with different anode geometries was prepared, La0.85Sr0.15MnO 3 (LSM) was selected as the cathode. Cells were tested at 800°C using humidified H2 as fuel. Cell with anode prepared by using pure water as non-solvent shows a maximum power density up to 437mW/cm 2. By comparing the anode geometry and electrochemical performance, it indicated that microstructure with longer finger-like pores and thinner macrovoid free layer close to the inner side of the tube is benefit to cell performance.;Another factor that can affect the microstructure of anode support is the ratio of solvent and polymer binder. In this research, anode-supported MT-SOFCs have been fabricated by phase inversion method. The effect of the viscosity of the casting slurry on the microstructure of YSZ-NiO anode support has been investigated. The microstructure of the YSZ-NiO support can be effectively controlled by varying the slurry composition with different solvent and polymer binder content. Gas permeation and mechanical strength of the YSZ-NiO support have been measured and four YSZ-NiO anode supports have been chosen for subsequent cell fabrication. The effective conductivity of the different anode supports has been measured at room temperature after reduced. Anode-supported single cells with YSZ electrolyte and LSM/YSZ cathode are fabricated and tested. Maximum cell power densities of 606 mWcm-2, 449 mWcm -2, 339 mWcm-2 and 253 mWcm-2 have been obtained respectively at 750 °C with humidified hydrogen as fuel and ambient air as oxidant. The correlation between the cell electrochemical performance and anode microstructures has been discussed.;Adjusting the slurry composition by introducing additive is also an effective approach to tailor the microstructure of the anode support. Poly(ethylene glycol) (PEG), which is a common applied polymer additive, was selected to fabricate the YSZ-NiO anode supports. The effect of molecular weight and amount of PEG additive on the thermodynamics of the casting solutions was characterized by measuring the coagulation value. Viscosity of the casting slurries was also measured and the influence of PEG additive on viscosity was studied and discussed. The presence of PEG in the casting slurry can greatly influence the final anode support microstructure. Based on the microstructure result and the measured gas permeation value, two anode supports were selected for cell fabrication. For cell with the anode support fabricated using slurry with PEG additive, a maximum cell power density of 704 mWcm-2 is obtained at 750 oC with humidified hydrogen as fuel and ambient air as oxidant; cell fabricated without any PEG additive shows the peak cell power density of 331 mWcm-2. The relationship between anode microstructure and cell performance was discussed.;Anode-supported micro-tubular solid oxide fuel cells (MT-SOFCs) based on BaZr0.1Ce0.7Y0.1Yb0.1O 3-delta (BZCYYb) proton-conducting electrolyte have been prepared using a phase inversion method. Three sulfur-free polymer binder candidates ethyl cellulose (EC), polyvinylidene fluoride (PVDF), polyetherimide (PEI) and sulfur-containing polythersulfone (PESf) were used as polymer binders to fabricate NiO-BZCYYb anode. The overall influence of polymer binder on the anode supports was evaluated. Sulfide impurity generated from PESf was revealed by XRD and X-ray photoelectron spectroscopy (XPS). The difference in the anode microstructure for samples fabricated by different polymer binders was examined by scanning electron microscope (SEM) and analyzed by measuring the gas permeation data of the reduced samples. Single cells based on different anode supports were characterized in anode-supported MT-SOFCs with the cell configuration of Ni-BZCYYb anode, BZCYYb electrolyte and La0.6Sr 0.4Co0.2Fe0.8O3-delta (LSCF)-BZCYYb cathode at 650 °C using hydrogen as fuel and ambient air as oxidant. MT-SOFCs of the anode fabricated using PEI show maximum power density of 0.45 Wcm -2 compared with 0.35 Wcm-2 for cells fabricated with PESf. The difference in cell performance was attributed to the phase purity of the anode fabricated by different polymer binders. Sulfur-free polymer binder PEI exhibits advantages over the commonly applied PESf and other sulfur-free polymer binder candidates.;To eliminate the skin layer formed close to the inner side of the tubular sample when using the phase inversion method. Polyethersulfone (PESf)-polyethylenimine (PEI) blend was employed as the polymer binder to fabricate the micro-tubular solid oxide fuel cells (MT-SOFCs). The potential impurity introduced in the anode support by the polymer binder was examined by XPS and the resulting novel microstructure was analyzed based on the backscattered electron (BSE) images. Cells fabricated with blend polymer binder showed significantly enhanced power output compared with those cells only fabricated with PEI or PESf. The improved cell performance demonstrated that using blend polymer as binder is a promising and versatile approach for MT-SOFC fabrication via phase inversion method.;Finally, to investigate the effect of the anode microstructure on the total cell performance, two types of anode support with different microstructure were prepared via the phase inversion method at different temperature. Cells fabricated based on these two anode supports were tested at 750 °C with hydrogen or hydrogen mixture with fuel gas. The measured current density-voltage (I-V) curves were fitted by a polarization model, and several parameters were archived through the modeling process. The influence of the anode support on the total cell performance was discussed based on the calculated result.
机译：如今，微管固体氧化物燃料电池（MT-SOFC），特别是阳极支撑的MT-SOFC已得到广泛开发，可用于SOFC堆的标识，可潜在地用于便携式电源和车辆电源。为了制备具有高电化学性能的MT-SOFC，主要策略之一是优化阳极载体的微观结构。近来，已经采用一种新颖的相转化方法来制备具有独特的不对称微结构的阳极载体，其可以改善MT-SOFC的电化学性能。由于相转化方法的几个工艺参数会影响孔的形成机理和最终的微观结构，因此有必要系统地研究相转化工艺参数与阳极载体最终微观结构之间的关系。这项研究的目的在于关联工艺参数和微观结构，并进一步制备具有增强的电化学性能的MT-SOFC .;用于触发相分离过程的非溶剂会显着影响所制造阳极载体的微观结构通过相位反转法。为了研究非溶剂影响微观结构的机理，选择水和乙醇/水混合物用于NiO-YSZ阳极载体的制备。非溶剂中乙醇的存在会抑制试管中手指状孔的生长。随着非溶剂中乙醇浓度的增加，在管的外部和内部都可以观察到相对致密的层。基于溶剂与非溶剂之间的相互扩散性，解释了使用非溶剂与高浓度乙醇获得的孔生长和形态的机理。 Dm值较大的溶剂和非溶剂对有利于手指状毛孔的生长。制备了三个具有不同阳极几何形状的电池，选择La0.85Sr0.15MnO 3（LSM）作为阴极。使用加湿氢气作为燃料在800°C下测试电池。用纯水作为非溶剂制备的带有阳极的电池，其最大功率密度高达437mW / cm 2。通过比较阳极的几何形状和电化学性能，它表明具有较长的手指状孔和较薄的大孔隙自由层的微观结构接近于管的内侧有利于电池性能。另一个可能影响阳极载体微观结构的因素是溶剂和聚合物粘合剂的比例。在这项研究中，已经通过相转化方法制备了阳极支撑的MT-SOFC。研究了浇注液粘度对YSZ-NiO阳极载体微观结构的影响。通过改变具有不同溶剂和聚合物粘合剂含量的浆料组成，可以有效地控制YSZ-NiO载体的微观结构。测量了YSZ-NiO载体的气体渗透性和机械强度，并选择了四个YSZ-NiO阳极载体用于随后的电池制造。还原后，已在室温下测量了不同阳极支撑体的有效电导率。制作并测试了带有YSZ电解质和LSM / YSZ阴极的阳极支撑单电池。在以湿氢为燃料，环境空气为氧化剂的情况下，分别在750°C下获得了606 mWcm-2、449 mWcm -2、339 mWcm-2和253 mWcm-2的最大电池功率密度。讨论了电池电化学性能与阳极微观结构之间的相关性。通过引入添加剂调节浆料组成也是调整阳极载体微观结构的有效方法。选择聚（乙二醇）（PEG），这是一种常用的聚合物添加剂，用于制造YSZ-NiO阳极载体。通过测量凝固值来表征分子量和PEG添加剂的量对浇铸溶液的热力学的影响。还测量了铸造浆料的粘度，并且研究和讨论了PEG添加剂对粘度的影响。浇铸浆料中PEG的存在会极大地影响最终的阳极载体微观结构。基于微观结构结果和测得的气体渗透值，选择了两个阳极支架进行电池制造。对于带有阳极支撑的电池，使用带有PEG添加剂的浆料制造，在750 oC下以湿化氢为燃料，周围空气为氧化剂，最大电池功率密度为704 mWcm-2。没有任何PEG添加剂制成的电池显示的峰值电池功率密度为331 mWcm-2。讨论了阳极微观结构与电池性能之间的关系。;已经建立了基于BaZr0.1Ce0.7Y0.1Yb0.1O 3-delta（BZCYYb）质子传导电解质的阳极支撑微管固体氧化物燃料电池（MT-SOFCs）。用反相法制备。三种无硫聚合物粘合剂候选物乙基纤维素（EC），聚偏二氟乙烯（PVDF），聚醚酰亚胺（PEI）和含硫聚醚砜（PESf）被用作聚合物粘合剂，以制备NiO-BZCYYb阳极。评估了聚合物粘合剂对阳极载体的总体影响。通过XRD和X射线光电子能谱（XPS）揭示了PESf产生的硫化物杂质。通过扫描电子显微镜（SEM）检查了由不同聚合物粘合剂制成的样品的阳极微观结构差异，并通过测量还原后样品的气体渗透数据进行了分析。在650°C下具有Ni-BZCYYb阳极，BZCYYb电解质和La0.6Sr 0.4Co0.2Fe0.8O3-delta（LSCF）-BZCYYb阴极的阳极构型的阳极支撑MT-SOFC中表征了基于不同阳极支撑的单电池使用氢气作为燃料，环境空气作为氧化剂。使用PEI制造的阳极的MT-SOFC的最大功率密度为0.45 Wcm -2，而使用PESf制造的电池的最大功率密度为0.35 Wcm -2。电池性能的差异归因于由不同聚合物粘合剂制成的阳极的相纯度。与常规应用的PESf和其他无硫聚合物粘合剂相比，无硫聚合物粘合剂PEI更具优势。;使用相转化法时，可消除在管状样品内侧附近形成的表皮层。聚醚砜（PESf）-聚乙烯亚胺（PEI）混合物用作聚合物粘合剂，以制造微管式固体氧化物燃料电池（MT-SOFC）。通过XPS检查了聚合物粘合剂在阳极载体中引入的潜在杂质，并基于背散射电子（BSE）图像分析了所得的新型微观结构。与仅使用PEI或PESf制成的电池相比，使用共混聚合物粘合剂制成的电池显示出显着增强的功率输出。改善的电池性能表明，使用共混聚合物作为粘合剂是通过相转化法制造MT-SOFC的一种有前途的通用方法。最后，研究阳极微结构对总电池性能的影响，两种类型的阳极载体通过相转化法在不同温度下制备出不同的组织。基于这两个阳极支架制造的电池在750°C下用氢气或氢气与燃料气体的混合物进行了测试。极化模型拟合了测得的电流密度-电压（I-V）曲线，并通过建模过程存储了一些参数。根据计算结果讨论了阳极载体对电池整体性能的影响。

著录项

  • 作者

    Ren, Cong.;

  • 作者单位

    University of South Carolina.;

  • 授予单位 University of South Carolina.;
  • 学科 Mechanical engineering.;Materials science.
  • 学位 Ph.D.
  • 年度 2015
  • 页码 127 p.
  • 总页数 127
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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