高温固体氧化物燃料电池实验演示

介绍一种高效低污染的新型能源－高温固体氧化物燃料电池的工作原理及其演示实验装置。     

固体氧化物燃料电池体系掺杂氧化锆的理论研究:从结构到导电性（英文）

固体氧化物燃料电池是一种将化学能(如H_2和O_2)转化为电能的清洁能源系统,它具有高效、低碳以及燃料适应性广的特点.作为燃料电池的"心脏",电解质决定了整个电池的性能,其中掺杂氧化锆是最为典型的燃料电池电解质材料.氧化钇稳定氧化锆在高温下具有优良的离子电导率,广泛应用在固体燃料电池中.电解质材料的组成和使用温度对电导率的影响在实验和理论上已得到了充分研究.复合氧化物的原子结构的表征是阐明其导电行为的关键,本文综述了氧化钇稳定氧化锆电解质的结构和导电性研究的最新理论进展,比较了研究该材料所采用的不同的理论方法及其相应结果,并总结了各种方法的优缺点.重点介绍了利用随机表面行走-神经网络方法取得的最新成果,这些成果和实验结果相吻合.结果表明,采用机器学习进行原子模拟为理解固体电解质中遇到的复杂物质现象提供了一种经济、高效和准确的方法.     

固体氧化物燃料电池

高效、洁净、全固态结构、高温运行的固体氧化物燃料电池(SOFC)是把反应物的化学能直接转化为电能的电化学装置，这种新型发电技术是目前发展最快的能源技术之一，有望在近年内走向商业化应用。SOFC单体电池由致密的电解质和多孔的阳极、阴极组成，现在主要发展了管状结构和平板式结构两种形式，单体电池通过致密的连接体材料以各种方式组装成电池组，广泛应用于大型发电厂、热电耦合设备、小型供能系统和交通工具等，市场前景广阔。     

21世纪的绿色能源--固体氧化物燃料电池(SOFC)

随着社会现代化程度的不断提高，全球对能源的需求也日趋增长．在人们物质生活水平得到不断提高的同时，环保意识也日益得到人们的重视．为使人们在提高生活水平的同时又能保护好环境，实现人与自然的和谐相处，就需要对传统的能量转换和废物再利用技术这两方面进行改革．其中，燃料     

固体氧化物直接碳燃料电池的模型计算

直接碳燃料电池(DCFC)是直接以碳或煤为燃料的燃料电池.本文以一种以固体氧化物为电解质的固定床直接碳燃料电池为对象,基于文献中的实验数据,建立了物理模型和数学方程,求解出电池在三个特定温度下的V-I曲线以及能量转换效率,并与文献中的实验结果进行对照,验证了对固定床直接碳燃料电池的反应过程的假设,分析了电池性能的影响因素,为直接碳燃料电池的应用打下了理论基础.     

固体氧化物燃料电池阳极微结构三维数值模拟

固体氧化物燃料电池(SOFC)是一种清洁高效的发电设备,其电极微结构直接影响电池的电化学性能。本文通过X-ray技术获取了SOFC阳极微结构,将电荷和物质传导定义在体相材料,将电化学反应定义在三相边界线上,建立了SOFC阳极电化学–传质耦合的三维微观模型,对比了两个微结构在80?C条件下的极化特性。研究表明微结构对电极内部物理场分布有极大影响,越靠近电极电解质界面,活化极化和离子电势波动越强烈。电极孔隙相细小的喉附近存在较大传质阻力,形成明显浓度极化跳跃。活化极化和欧姆极化大小相当,各占据总损失的45%以上。本文模型可用于研究微结构改变引起的电池退化和电极的优化设计。     

中温固体氧化物燃料电池的基本性质测量

介绍了固体氧化物燃料电池的工作原理,测量了中温薄膜固体氧化物燃料电池的开路电压、放电曲线及功率曲线,并分析了电池内阻随电流密度的变化.     

固体氧化物燃料电池温升模拟中入口异常高温度梯度研究

针对固体氧化物燃料电池热循环失效问题,建立了固体氧化物燃料电池热气体预热动态模型,研究了电池内最大温度梯度分布规律和入口异常高温度梯度形成的原因,结果表明:在热气体参数和预热方式变化时,电池内最大温度梯度始终处于电池入口边缘处的电极表面;电池入口处存在异常高的温度梯度,且在入口一小段区域内,温度梯度沿流动方向迅速下降;其原因是模型中入口采用均一的平均速度和温度,“入口效应”强化气体与电池换热;采用入口段延长的方式可使入口速度充分发展,降低电池内最大温度梯度,但由于均一温度入口并未优化,入口处仍然存在很大的温度梯度和温度梯度变化;因此采用数值模拟研究电池预热升温安全性时,仅采用最大温度梯度作为安全性判据会高估电池内热应力.     

平板式固体氧化物燃料电池多物理场耦合建模

固体氧化物燃料电池(Solid oxide fuel cell,SOFC)在高温下工作,影响电池性能和结构完整性的因素众多,如何能够综合考虑这些因素并准确地预测和优化电池结构与工作性能是亟待解决的问题。使用COMSOL软件建立了单个平板式固体氧化物燃料电池多场耦合有限元三维模型,考虑电化学反应、物质浓度、流体流动、传热和固体力学多物理因素共同作用下,探明了电池在工作阶段的气体摩尔分数、电流密度、温度和热应力的分布规律。结果表明,氢气和氧气的摩尔分数随着气体流动的方向逐渐降低;在电池空气入口处,电解质电流密度较大;电池温度分布不均匀并产生了较大的热应力。本文建立的SOFC多场耦合模型可为后续SOFC的研究提供分析方法和理论支持。     

生物质气为燃料的燃料电池理论电动势计算

在以生物质气体为燃料的固体氧化物燃料电池体系中,通过热力学平衡分析编程计算出700-1200 K时气体中各物种例如H2、CO、CO2和CH4的平衡组成,从而得到以氧化钇稳定氧化锆(YSZ)为电解质的电池理论电动势．碳沉积对电动势有显著影响．通过计算可以推测比较适宜的操作温度和增湿条件．还计算了以掺杂氧化铈为电解质的电池电动势,相比氢气为燃料时,使用生物质气体导致的电动势的下降比使用YSZ为电解质的电池要小的多．     

Performance of double layer electrolyte cells Part I: Model behavior

The present work reports on the estimated performance of double layer electrolyte based cells, including one yttria stabilized zirconia (YSZ) electron blocking layer. In order to evaluate the impact of the relative magnitude of the materials properties on the cell performance, a range of electrical properties has been considered, taking YSZ as reference. At constant temperature, the open circuit voltage, the oxygen permeability and the oxygen partial pressure profiles in such two layer electrolyte cells are related to the materials ionic and electronic transport properties, layers thickness and overall cell oxygen partial pressure boundary conditions. The effectiveness of the electron blocking characteristics of YSZ layers is demonstrated for a variety of materials, but consideration of the exact electrical properties (the n-type but also the p-type and ionic conductivities) of the second electrolyte layer is shown to be a fundamental requirement for proper design of such cells.     

Samaria-doped Ceria Modified Ni/YSZ Anode for Direct Methane Fuel in Tubular Solid Oxide Fuel Cells by Impregnation Method

以NiO和8%(摩尔分数)氧化钇稳定的氧化锆为原料,采用注凝成型工艺制备了管状固体氧化物燃料电池阳极支撑体．用离子浸渍法对阳极支撑体进行表面修饰．用电化学工作站测单电池交流阻抗和输出性能并且用化学气相色谱仪对电池尾气进行分析．测试结果表明修饰后的阳极在通甲烷的情况下出现了一定程度的积炭,但是积炭现象在一定的测试时间内达到平衡,没有对电池造成破坏,并且显著地提高了电池阳极的电化学性能．单电池在通入氢气和甲烷的情况下最大输出功率密度分别达到了225和400 mW/cm²．     

Preparation of honeycomb porous La0.6Sr0.4Co0.2Fe0.8O3−δ-Gd0.2Ce0.8O2−δ composite cathodes by breath figures method for solid oxide fuel cells

Honeycomb porous La_0.6Sr_0.4Co_0.2Fe_0.8O_3−δ-Gd_0.2Ce_0.8O_2−δ (LSCF-GDC) composite cathodes are prepared using the breath figures (BFs) method with nontoxic and easily available water droplets as templates. The fabrication of honeycomb porous membranes is realized in a relatively humid environment, using a volatile solvent. The microstructure and morphology of the membranes produced are investigated by scanning electron microscopy (SEM). The SEM micrographs suggest that experimental conditions, such as ambient temperature, relative humidity, and concentration of polymer and LSCF-GDC powder, which have direct influence on the solvent evaporation affects the pore structure of the porous membranes. Electrochemical impedance spectroscopy (EIS) is used to evaluate the polarization resistance of LSCF-GDC composite cathodes prepared at different experimental conditions. The honeycomb porous LSCF-GDC composite cathode showing average pore diameter of 10 μm illustrates the lowest polarization resistance.     

Electrodeposited cobalt coating on Crofer22APU steels for interconnect applications in solid oxide fuel cells

A gas-tight cobalt-based protective coating was successfully applied by electroplating and subsequent oxidation. The coating covered all the surfaces of the machined gas channels of the metallic interconnect and adhered well to this substrate. Such a gas-tight coating offers effective blocking of Cr diffusion or evaporation from the interconnect and hence a reliable protection against Cr poisoning of the SOFC cathode. Chemical interactions were observed between the cobalt coating and the LSM contact layer, resulting in layer spallation during oxidation under pressureless conditions. Applying a pressure to the layers, spallation was effectively prevented. Although the area specific resistance (ASR) of the coated interconnect was higher than the uncoated one, it decreased steadily with time within the measurement period. The ASR was 28 mΩ cm² after an exposure of 1170 h. It seems thus that electroplating followed by oxidation is a promising method for the fabrication of spinel protective coatings for SOFC interconnects or other balance-of-plant components with complicated gas flow paths.     

Niobium based tetragonal tungsten bronzes as potential anodes for solid oxide fuel cells: synthesis and electrical characterisation

In this paper we report studies on a range of niobate based tungsten bronzes, with a view to analysing their potential as anode materials in SOFCs. Six systems were studied, (Sr_1−xBa_x)_0.6Ti_0.2Nb_0.8O₃, Sr_0.6−xLa_xTi_0.2+xNb_0.8−xO₃, (Sr_0.4−xBa_x)Na_0.2NbO₃, (Ba_1−xCa_x)_0.6Ti_0.2Nb_0.8O₃, Ba_0.5−xA_xNbO₃ (A=Ca, Sr), and Ba_0.3NbO_2.8, and the electrical conductivities were examined over a range of oxygen partial pressures (10⁻²⁰–1 bar). All the systems showed good conductivity in low oxygen partial pressures, with values as high as 8 S cm⁻¹ at 930°C (P(O₂)=10⁻²⁰ bar). As the oxygen partial pressure was raised the conductivity dropped showing in most cases an approximate [P(O₂)]^−1/4 dependence and good re-oxidation kinetics. Of all the samples studied the (Sr_1−xBa_x)_0.6Ti_0.2Nb_0.8O₃ and (Ba_1−xCa_x)_0.6Ti_0.2Nb_0.8O₃ systems appear most promising for potential use as anode materials in SOFCs.     

Ultrathin‐Carbon‐Layer‐Protected PtCu Nanoparticles Encapsulated in Carbon Capsules: A Structure Engineering of the Anode Electrocatalyst for Direct Formic Acid Fuel Cells

Structure engineering is an effective strategy to enhance the performance of electrocatalysts for the formic acid oxidation reaction. However, it remains a challenge to prepare a highly active electrocatalyst based on a distinct understanding of its structure‐dependent performance. The design and synthesis of ultrathin‐carbon‐layer‐protected PtCu nanoparticles (NPs) encapsulated in a N‐doped carbon capsule (PtCu@NCC) is reported. This system is fabricated by using Zn‐based metal–organic frameworks as the carbon support source and metal‐containing tannic acid as the protecting shell template. It displays 9.8‐ and 9.6‐fold enhancements in mass activity and specific activity compared to commercial Pt/C. Moreover, a constructed direct formic acid fuel cell using PtCu@NCC as the anodic electrocatalyst delivers a maximum power density of 121 mW cm^?2. Significantly, PtCu@NCC exhibits superior structural stability and catalytic durability in both half‐cell and full‐cell tests. A mechanism study reveals that the enhanced activity is partially attributed to facilitated electro‐oxidation kinetics of formic acid in the unique structure of PtCu@NCC, while the excellent durability stems from the “protecting effect” of the in‐situ‐formed ultrathin carbon layer on the surface of the PtCu NPs. This work opens a new avenue for the development of high‐performance electrocatalysts for fuel‐cell applications by offering essential insights into the structure–performance relationship of the materials.     

Cr2O3催化合成气转化至甲醇的微观动力学研究

Cr₂O₃是双功能催化合成气转化的重要氧化物组分,其可将合成气转化为重要的中间物种甲醇. 结合密度泛函理论计算和微观动力学模拟,本文系统研究了干净Cr₂O₃(001)和(012)表面,以及氢覆盖或含有氧空位的还原(012)表面的结构及催化合成气转化至甲醇的活性. 本文探讨了合成气转化为甲醇的分步或协同反应路径,并确定CO或CHO氢化是决速步骤. 微观动力学分析表明,Cr₂O₃(001)表面难以催化合成气转化为甲醇,在673 K 时,两个还原性(012)表面的反应速率(25∽28 s^-1)比干净的(012)表面(4.3 s^-1)高出约五倍. 计算结果表明了Cr₂O₃表面还原性对催化活性的重要性,或许可以为双功能催化体系中氧化物组分的设计提供参考.