Direct-write fabrication of integrated planar solid oxide fuel cells

Integrated planar solid oxide fuel cell (IP-SOFC) with multilayered structure has been fabricated via direct-writing process named robo-dispensing. Partially stabilized zirconia (PSZ) substrate with sufficient mechanical strength and gas permeability was utilized as a support for SOFC. The 2-cells serially integrated planar SOFC in which each cell is composed of the line-shaped electrode and electrolyte was produced The SOFC component paste materials were dispensed through cylindrical nozzle of 0.21 mm in diameter onto a moving plate that was controlled by robo-dispensing machine. The thicknesses of anode, electrolyte and cathode were 30 μm, 15 μm and 20 μm, respectively. The fabricated IP-SOFC exhibited OCV of 1.82 V and maximum power density of 35 mW.     

Fuel cell high-power applications

Energy consumption plays an important role in our modern civilization and daily life, which is heavily dependent on burning fossil fuels. The increasing threat of the fast depletion of resources such as petroleum, coal, and natural gas forces people to seek regenerative energy sources, such as solar, wind, geothermal, and hydroelectric energies. Another way of saving valuable natural resources and solving the environmental problem is to develop cleaner and more efficient energy conversion devices. In recent years, fuel cell (FC) research and development have received much attention for their higher energy conversion efficiency and lower or nongreenhousegas emissions than thermal engines in the processes of converting fuel into usable energies [1]-[3]. The power and energy efficiency of an FC is highly dependent on thermodynamics, electrode kinetics, and reactant mass transfer, as well as materials and components for assembling the FC. These factors have been addressed throughout the FC history and are now still the major challenges for FC research and development [4]-[6].     

固体氧化物燃料电池阴极数学模型与性能分析

该文针对固体氧化物燃料电池（SOFC）的LSM/YSZ(Sr掺杂LaMnO3 / Y2O3稳定ZrO2)多孔阴极，耦合电极内部离子传导、电子传导、气体扩散与电化学反应过程，建立了全面考虑活化极化、欧姆极化与浓差极化的电极微观数学模型。模型对交换电流密度计算子模型进行了改进，揭示了温度、氧气分压对其的影响，并将三相界 (TPB )定量表示为电极微观结构参数（孔隙率，配位数，接触角等）的函数。模型计算结果与文献中实验数据吻合较好。在此基础上利用该模型对过电位、氧气浓度等参数在电极上的分布进行计算，并研究了混合导体颗粒尺寸、氧气利用率、电极厚度、孔隙结构参数对电极极化的影响。模拟结果对电极微观结构优化及电池运行提供了一定的理论指导。     

Structural and electrical transport properties of Pr-doped SrTi 0.93 Co 0.07 O 3-δ a novel SOEC fuel electrode materials

Solid Oxide Electrolyzer Cells (SOECs) are very promising electrochemical devices for the production of syngas (H2/CO) by H2O and CO2 co-electrolysis. The structure, microstructure and electrical properties of the fuel electrode material play a crucial role in the performance of the whole cell and efficiency of electrocatalytic reduction of steam into hydrogen. In the present work, a novel Co and Pr co-doped SrTiO3-δ material attracted attention as a potential fuel electrode for SOFC/SOEC. Materials with different praseodymium content were prepared by a solid-state reaction process. XRD confirmed cubic perovskite structure in all obtained samples. SEM results showed porosity in doped materials and EDX proved ABO3 stoichiometry. TEC values were about 1.17–1.26•10−5 K−1 very close to the YSZ electrolyte value. XPS studies turn out that a praseodymium can be multivalent and exist on mixed +3 and + 4 oxidation state. Electrical conductivity of samples was measured by DC 4-wire method in range of 100-800 °C. Highest value of total conductivity was achieved for Sr0.7Pr0.3Ti0.93Co0.07O3-δ and reached 23.7 S∙cm−1. The obtained results were discussed and analyzed in term of defect chemistry.     

CH_4-O_2固体氧化物燃料电池化学反应研究

研究了以甲烷为燃料气体、空气为氧化气体的固体氧化物燃料电池中的主要化学反应。同时研究了固体氧化物燃料电池电极结构、三相界面（电解质／电极／气体）结构和运行环境以及它们对电池主要化学反应的影响。并通过研究Ｐｔ｜ＹＳＺ｜Ａｇ固体氧化物燃料电池的开路电压与甲烷流量的关系,探讨燃料电池中的主要化学反应过程对电池性能的影响。研究表明,增加电极的孔隙率,可以增加三相界面的面积,从而增加有效反应区域,有利于电池反应。提高运行温度和阴极室氧的浓度,可以提高甲烷的利用率和电池的性能。     

固体氧化物燃料电池阳极材料的研究进展

固体氧化物燃料电池(SOFC)因具有能量转换率高,燃料适应性强,环境友好和操作方便等优点,受到了人们的普遍关注,但是SOFC的广泛应用还有待于其关键材料的进一步发展.介绍了SOFC对阳极材料的基本要求,对阳极材料研究进展进行评述.重点对各种阳极材料(金属、YSZ金属陶瓷、Cu基金属陶瓷、Ce基氧化物以及钙钛矿氧化物等)性能方面的优缺点进行比较,并着重介绍了钙钛矿阳极材料f铬酸镧基氧化物)的进展情况.对改进阳极材料性能的各种措施进行了归纳和总结.     

以煤层气为燃料的固体氧化物燃料电池发电系统的模拟与分析

固体氧化物燃料电池(solid oxide fuel cell,SOFC)发电具有效率高、噪声低、排放低的优点。为评估煤层气SOFC发电系统性能,并与现有燃气内燃机发电技术进行对比,在AspenPlus模拟环境中构建了SOFC发电系统流程,研究30%和91%煤层气浓度下水碳比、电流密度、空气预热温度等参数对系统性能的影响,并与燃气内燃机发电进行技术经济性比较。结果表明,使用30%浓度煤层气时,SOFC发电效率为38.7%,略低于燃气内燃机发电效率,年CO2排放量与燃气内燃机接近;使用91%浓度煤层气时,SOFC发电效率为53.2%,高出燃气内燃机13.4%,年燃料成本降低24%,年CO2排放量相比燃气内燃机降低23%;受大量冷却空气的影响,SOFC的NOx排放是燃气内燃机的2倍。由结果可知,当煤层气浓度在30%以上时,SOFC相比燃气内燃机才具有效率优势;煤层气浓度越高,SOFC的效率优势越明显;当煤层气浓度低于30%时,建议仍使用燃气内燃机进行发电。     

固体氧化物燃料电池传感器检测变压器油中溶解气体定量特性

在线油色谱法是目前公认的发现变压器潜伏性故障的重要检测方法,对变压器运行状态的评估具有重要意义。气体传感器是在线色谱的关键技术。目前,国内外研制了许多油色谱在线监测传感器,但都存在灵敏度不高、线性范围难以满足要求等缺点,上述缺陷限制了在线色谱技术取代传统的离线检测技术。针对上述问题,提出一种固体氧化物燃料电池传感器检测变压器油中溶解气体的方法,介绍了传感器的制备方法、实验方法及步骤,并对油中气体的气敏响应机制进行探讨。在此基础上,基于Nernst方程构建传感器的定量数学模型。实验结果表明,固体氧化物燃料电池(SOFC)检测器技术及该文构建的模型能实现H_2、CH_4、C_2H_4、C_2H_6和C_2H_2的准确定量及高精度测量,对C_2H_2的灵敏度达到1×10~(-7),能较好地解决常规传感器及其定量方法稳定性差、准确性和灵敏度低等问题,具有重要的推广及应用价值。     

钙钛矿型SOFC阴极材料的研究进展

阴极是固体氧化物燃料电池(SOFC)的重要部件之一,阴极的性能对SOFC的性能(尤其是低温SOFC的性能)起着决定性的作用,阴极的界面电阻是整个电池电阻的70%～85%.ABO2型钙钛矿稀土复合氧化物是目前最普遍应用的固体氧化物燃料电池的阴极材料,钙钛矿材料的结构特点决定了该材料具有电子-离子混合导电性.对固体氧化物燃料电池阴极材料的催化机理、制备方法、复合梯度阴极进行了详细的描述,并提出了通过改善微结构来提高低温阴极材料的性能是今后发展的主要方向.     

固体氧化物燃料电池阳极结构研究进展

概述了有关固体氧化物燃料电池(SOFC)阳极结构研究的进展,探讨了阳极的组成材料、孔隙率、孔的微观结构、多层结构以及界面性质等因素对SOFC性能的影响。分析了多孔阳极的微观结构,指出各向异性的孔状结构会损害阳极性能。总结了阳极材料制备工艺参数对阳极孔隙率的影响。比较了近年来开发的几种多层阳极并指出其结构特点以及制备工艺的难点。介绍了加入混合导体层来改善SOFC电极/电解质界面性质的方法。     

Doping of SiGe core-shell nanowires

Dopant deactivation in pure Si and pure Ge nanowires (NWs) can compromise the efficiency of the doping process at nanoscale. Quantum confinement, surface segregation and dielectric mismatch, in different ways, strongly reduce the carrier generation induced by intentional addition of dopants. This issue seems to be critical for the fabrication of high-quality electrical devices for various future applications, such as photovoltaics and nanoelectronics. By means of Density Functional Theory simulations, we show how this limit can be rode out in core-shell silicon-germanium NWs (SiGe NWs), playing on the particular energy band alignment that comes out at the Si/Ge interface. We demonstrate how, by choosing the appropriate doping configurations, it is possible to obtain a 1-D electron or hole gas, which has not to be thermally activated and which can furnish carriers also at very low temperatures. Our findings suggest core-shell NWs as possible building blocks for high-speed electronic device and new generation solar cells.     

The Effects of Integration Processes on Properties of One Transistor MFMPOS Memory Devices

Integration processing of one-transistor memory devices deals with the following issues: film quality of ferroelectric materials, integration process induced damages such as etching and forming gas annealing damage of ferroelectric materials, the alignment for devices. In order to make high quality one-transistor memory devices, integration processes including nitride gate replacement, oxide trench etching structures, selective deposition, etc. have been investigated for fabrication of one transistor MFMPOS (M: Metal, F: Ferroelectrics, M: Metal, P: polysilicon, O: oxide, S: silicon) memory devices. The integration processes for one transistor memory device have also been optimized to reduce process-induced damages. Based on the experimental results, MOCVD selective deposition can make higher quality patterned ferroelectric thin films, damascene structure with CMP processes can reduce the etching damages. Therefore, the high quality one transistor MFMPOS memory devices have been made.     

Fabrication of MgO-coated TiO2 nanotubes and application to dye-sensitized solar cells

Dye-sensitized solar cells (DSCs) are more spotlighted than conventional photovoltaic devices due to their relatively low cost, easy fabrication and high efficiency. However, there are limitations to increase the conversion efficiency of DSCs. The limiting factors are the quantity of dye adsorption and charge recombination between TiO₂ electrode and electrolyte. Coating other materials such as high energy band gap insulators or semiconductors on the TiO₂ electrode enhances dye adsorption and reduces charge recombination. We fabricated DSCs based on bare TiO₂ nanotube arrays and 0.02 and 0.04 M MgO coated TiO₂ nanotube arrays. MgO layer increased the photovoltage and photocurrent. The overall conversion efficiency of DSCs using 0.02 M MgO coated TiO₂ nanotubes was 1.61%. MgO formed insulating layers between TiO₂ nanotube array electrode and electrolyte. Charge recombination was inhibited at the interfaces of TiO₂ nanotube array electrode and electrolyte by MgO insulating layers. MgO coating also improved dye adsorption because iso-electric point (IEP) of MgO was larger than TiO₂. When the IEP of coating material is larger than TiO₂, the chemical attraction between the electrode surface and Ru-based dye molecule is increased.     

Numerical modeling of micro single-chamber ceria-based SOFC

Performance of intermediate temperature SOFC system of micro scale single-chamber with composite electrodes alternately placed on the ceria-based electrolyte has been successfully evaluated by numerical modeling. The polarization curve was obtained through a series of calculations for ohmic loss, activation loss and concentration loss. The calculation of each loss was based on the consideration of fluid dynamics, convection of fuel-air gas mixture, diffusion and oxygen ion conduction. The performance characteristics of SOFC were quantitatively investigated for various structural parameters such as distance between electrodes and thickness of electrolyte and electrode. The effect of the inflow direction of fuel-air mixture on the performance of the fuel cell was analyzed.     

固体氧化物燃料电池的效率分析

固体氧化物燃料电池(SOFC)具有很高的理论能量转换效率,但是目前报道的实际SOFC单体性能远不能达到理论转换效率。从热力学理论及实验数据出发解释了SOFC单体性能远不能达到理论效率的原因,针对电压效率、电流效率和燃料利用率分别提出了相应的改进方法,为SOFC的进一步发展提供理论依据。其中温度对电压效率、电流效率和燃料利用率有重要的影响,提高温度可以提高这三者的值,但是提高温度将降低SOFC的热力学理论效率。     

Cathodic Polarization Study on Doped Lanthanum Gallate Electrolyte Using Impedance Spectroscopy

The perovskite electrolyte La_{1 – x}Sr_xGa_{1 – y}Mg_yO₃ (LSGM) has received a lot of interest in recent years after it was first reported to have significantly higher oxygen-ion conductivity than conventional YSZ. A very large fraction of the total polarization losses in SOFC is known to occur at the electrode-electrolyte interfaces manifesting itself as the kinetic barrier to charge-transfer reactions. AC complex impedance spectroscopy studies were conducted on symmetrical cells of the type [air, electrode/LSGM electrolyte/electrode, air] to measure the charge-transfer polarization at the cathode-electrolyte interfaces. The electrode materials were slurry-coated on both sides of the LSGM electrolyte support. The cathode materials investigated in this study include La_{1 – x}Sr_xMnO₃(LSM), LSCF (La_{1 – x}Sr_xCo_yFe_{1 – y}O₃) and a two-phase particulate composite consisting of LSM +doped-lanthanum gallate (LSGM). Symmetrical cell studies were also performed on SOFC anode materials. The principal anode material investigated in this study is a porous composite of Ni-gadolinium doped ceria (GDC). It is well known that Ni reacts with the state-of-the-art LSGM anode material. Thus our approach is to use a barrier layer of GDC between the Ni-GDC anode and the LSGM electrolyte. This paper will focus on the influence of microstructure, electrode composition, electrode thickness, interfacial compatibility and electrode processing conditions on cathode and anode polarization.     

纳米复合氢氧化镍电极研究

纳米氢氧化镍材料是一种高效的镍电极材料 ,纳米级镍电极的制备方法对镍电极电化学性能的影响很大。研究结果表明 :分散处理的纳米氢氧化镍颗粒制备的镍电极在容量与放电平台方面高于未处理的电极 ;纳米复合镍电极的电化学性能优于纳米镍电极。分散处理的纳米氢氧化镍颗粒组装而成的纳米复合镍电极电化学性能超过了常规球镍电极。纳米颗粒团聚的减轻与纳米颗粒的流动性 ,使纳米复合电极的导电性能与质子传导性能明显改善是分散处理纳米复合镍电极具有优良电化学性能的原因。     

Numerical investigation of the staged gasification of wet wood

Gasification of wooden biomass makes it possible to utilize forestry wastes and agricultural residues for generation of heat and power in isolated small-scale power systems. In spite of the availability of a huge amount of cheap biomass, the implementation of the gasification process is impeded by formation of tar products and poor thermal stability of the process. These factors reduce the competitiveness of gasification as compared with alternative technologies. The use of staged technologies enables certain disadvantages of conventional processes to be avoided. One of the previously proposed staged processes is investigated in this paper. For this purpose, mathematical models were developed for individual stages of the process, such as pyrolysis, pyrolysis gas combustion, and semicoke gasification. The effect of controlling parameters on the efficiency of fuel conversion into combustible gases is studied numerically using these models. For the controlling parameter are selected heat inputted into a pyrolysis reactor, the excess of oxidizer during gas combustion, and the wood moisture content. The process efficiency criterion is the gasification chemical efficiency accounting for the input of external heat (used for fuel drying and pyrolysis). The generated regime diagrams represent the gasification efficiency as a function of controlling parameters. Modeling results demonstrate that an increase in the fraction of heat supplied from an external source can result in an adequate efficiency of the wood gasification through the use of steam generated during drying. There are regions where it is feasible to perform incomplete combustion of the pyrolysis gas prior to the gasification. The calculated chemical efficiency of the staged gasification is as high as 80–85%, which is 10–20% higher that in conventional single-stage processes.     

管型固体氧化物燃料电池技术进展

叙述了以阴极、阳极、电解质、多孔陶瓷为支撑体的各类管型固体氧化物燃料电池(SOFC)的研发现状;介绍了西门子-西屋动力公司发展管型SOFC热电联供和联合循环发电技术的进展.发展以管型SOFC为主体的联合循环发电-热电联供的洁净能源供应系统,可提高以煤、天然气等燃料的发电效率,形成用户端的直接电、热、冷联供网络.     

Comprehensive summary of solid oxide fuel cell control: a state-of-the-art review

A thermoelectric generation (TEG) system has the weakness of relatively low thermoelectric conversion efficiency caused by heterogeneous temperature distribution (HgTD). Dynamic reconfiguration is an effective technique to improve its overall energy efficiency under HgTD. Nevertheless, numerous combinations of electrical switches make dynamic reconfiguration a complex combinatorial optimization problem. This paper aims to design a novel adaptive coordinated seeker (ACS) based on an optimal configuration strategy for large-scale TEG systems with series–parallel connected modules under HgTDs. To properly balance global exploration and local exploitation, ACS is based on ‘divide-and-conquer’ parallel computing, which synthetically coordinates the local searching capability of tabu search (TS) and the global searching capability of a pelican optimization algorithm (POA) during iterations. In addition, an equivalent re-optimization strategy for a reconfiguration solution obtained by meta-heuristic algorithms (MhAs) is proposed to reduce redundant switching actions caused by the randomness of MhAs. Two case studies are carried out to assess the feasibility and superiority of ACS in comparison with the artificial bee colony algorithm, ant colony optimization, genetic algorithm, particle swarm optimization, simulated annealing algorithm, TS, and POA. Simulation results indicate that ACS can realize fast and stable dynamic reconfiguration of a TEG system under HgTDs. In addition, RTLAB platform-based hardware-in-the-loop experiments are carried out to further validate the hardware implementation feasibility.