直接碳氢化合物固体氧化物燃料电池

直接碳氢化合物固体氧化物燃料电池(D-HC SOFC)具有能量密度高和运行成本低等特点,可望在便携式电源等方面得到广泛应用,已成为国际上SOFC领域的研究热点。本文对D-HC SOFC进行了热力学分析,综述了目前国际上在D-HC SOFC研究方面的现状,指出现有的D-HC SOFC研究工作绝大多数都是围绕着如何避免积碳进行。围绕着避免积碳的3条途径即降低工作温度、采用合适的催化剂和促进电化学氧化,对D-HC SOFC研究进行了阐述和讨论。文中还提到一些阳极反应机理方面的研究,并对今后的D-HC SOFC工作提出了作者的观点,认为应该在D-HC SOFC电池组方面和涉及到气体分布的阳极反应机理方面做更多工作。     

A Carbon–Air Battery for High Power Generation

We report a carbon–air battery for power generation based on a solid‐oxide fuel cell (SOFC) integrated with a ceramic CO₂‐permeable membrane. An anode‐supported tubular SOFC functioned as a carbon fuel container as well as an electrochemical device for power generation, while a high‐temperature CO₂‐permeable membrane composed of a CO₃^2? mixture and an O^2? conducting phase (Sm_0.2Ce_0.8O_1.9) was integrated for in situ separation of CO₂ (electrochemical product) from the anode chamber, delivering high fuel‐utilization efficiency. After modifying the carbon fuel with a reverse Boudouard reaction catalyst to promote the in situ gasification of carbon to CO, an attractive peak power density of 279.3 mW cm^?2 was achieved for the battery at 850 °C, and a small stack composed of two batteries can be operated continuously for 200 min. This work provides a novel type of electrochemical energy device that has a wide range of application potentials.     

Gas dynamics in channels of a gas-feed direct methanol fuel cell: exact solutions

The gas dynamics in channels on both sides of a gas-feed direct methanol fuel cell (DFMC) are considered. The basic equations for the flow velocity and density are derived, taking into account the mass and momentum transfer through the channel/backing layer interface. For the practical case of small inlet velocities the analog of the Bernoulli equation is formulated and the exact solution of nonlinear gas dynamics equations is obtained. It is shown that the flow in both the cathode and anode channels is incompressible (its density is constant) and electrochemical reactions affect only the flow velocity v. Simple formulae for v as a function of local current density and effective water drag coefficient are derived.     

真空注浆法制备YSZ电解质膜管及其在固体氧化物燃料电池中的应用

以吡啶为分散剂,采用真空注浆法制备出膜厚为0.2mm、长度为140mm的致密YSZ电解质膜管。研究了烧结温度对样品致密度和离子导电率的影响.用1650℃烧结2h制备的致密YSZ电解质膜管组装成固体氧化物燃料电池,以氢气和煤气为燃料,研究了电池在500～900℃的电化学性能.实验结果表明,用真空注浆法可制备出高质量和高密度的YSZ电解质膜管,在1600℃烧结后,其相对密度已达到理论密度的98.1%,接近理论密度.单电池的开路电压最大值为1.213V,最大输出功率为0.48W.以氢气为燃料的燃料电池性能明显高于以煤气为燃料的电池性能.     

基于电-化-热耦合理论对称双阴极固体氧化物燃料电池堆的电流与温度场数值模拟

本文基于电-化-热多场耦合理论,通过有限元方法建立了一个基于对称双阴极结构SOFC电堆单元的三维数值模型,研究了其电堆内部的电流密度分布和温度分布. 研究结果表明,气体流动方式以及集流方式影响了电解质上电流密度和温度分布：在气体进、出气口处有较大的电流密度分布;在气体共流模式下,电解质层温度分布却较均匀;在双阴极结构电池阴极侧的单一集流模式下,集流侧的电解质的平均电流密度高于另一侧.     

钙钛矿材料在固体氧化物燃料电池燃料重整中的应用

固体氧化物燃料电池（solid oxide fuel cell,SOFC）是通过电化学反应将化石燃料（煤、石油和天然气等）、生物质燃料或其它碳氢燃料中的化学能直接转换为电能的发电装置,能量转换效率更高、污染更低,被公认为21世纪高效绿色能源技术. 但直接以碳氢化合物为燃料时,镍基阳极中容易产生积碳,从而失去电化学催化活性. 在阳极外侧进行一次燃料的预重整是一种行之有效的解决办法,其中高效稳定的重整催化剂至关重要. 本文将结合本课题组的研究进展对钙钛矿催化剂在燃料重整中的应用进行概述,并提出自己相应的观点和展望.     

Electrochemical Noise Measurement of Polymer Membrane Fuel Cell under Load

Electrochemical noise of a polymer membrane hydrogen–air fuel cell under different currents is measured. Frequency and amplitude dependences of the current-noise power spectral density are calculated. In the frequency interval from 10 to 200 Hz a linear segment of the frequency characteristic has a slope of ?2. The current-noise power spectral density is found to be proportional to the 4th power of the fuel cell loading DC current. Thus found frequency dependence of the fuel cell electrochemical noise was shown to differ markedly from that of the electrochemical impedance real component.     

Comparison of characteristics of solid oxide fuel cells with YSZ and CGO film solid electrolytes formed using magnetron sputtering technique

The work describes the methods of manufacturing single cells of solid oxide fuel cell (SOFC) with thin–film YSZ and CGO electrolytes and also with the bilayer YSZ/CGO electrolyte. Formation of YSZ and CGO films on the supporting NiO–YSZ anode of SOFC was carried out using the combined electron–ionic–plasma deposition technique. The microstructure and phase composition of the formed coatings are studied and also comparative analysis of electrochemical characteristics of single fuel cells with different electrolytes is performed. It is shown that the maximum power density of 1.35 W/cm² at the temperature of 800°C is obtained for the cell with bilayer YSZ/CGO electrolyte. However, the highest performance at lower working temperatures (650–700°C) is characteristic for the fuel cell with single–layer CGO electrolyte; its power density is 600–650 mW/cm².     

中温复合固体电解质SDC-LSGM的制备和性能

采用甘氨酸-硝酸盐法分别制备了Ce0.85Sm0.15O2-δ(SDC)与La0.9Sr0.1Ga0.8Mg0.2O3-δ(LSGM)两种电解质材料, 并用固相混合法将两种材料按不同质量比(SDC与LSGM的质量比分别为9∶1, 8∶2, 5∶5)混合制备复合电解质材料. 采用交流阻抗技术对样品的电学性能进行研究. 实验结果表明, SDC与LSGM的质量比为9∶1(SL91)时, 样品具有较高的电导率, 在350—800 ℃温度范围内其电导率均比SDC的高. 以复合电解质为支撑体, 以Sm0.5Sr0.5CoO3 为阴极、NiO/SDC 为阳极制成单电池, 测试结果显示, 在800 ℃时以SL91为电解质的单电池的最大输出功率密度为0.25 W/cm2, 最大电流密度为1.06 A/cm2. 在电池的工作温度区间(600—800 ℃)内以复合材料为电解质的单电池的开路电压比以SDC为电解质的高.     

非贵金属催化的碱性硫离子燃料电池放电特性

燃料的选择对于燃料电池电极催化剂的选择、燃料电池的成本及其商业化有着至关重要的影响寻求电化学活性好、成本低,并且能够为非贵金属催化剂所催化的燃料是一项有前景的工作.硫离子的电化学活性及其低成本使之成为一个具有吸引力的选择.本文以碱性硫离子作为燃料构建了碱性硫离子燃料电池.在室温条件下,单体电池在以非贵金属为催化剂的条件下获得了12.3 mW· cm-2的功率密度,此时的电流密度达到了42.8 mA·cm-2; 50 h寿命测试显示了碱性硫离子燃料电池良好的稳定性.此外,通过离子色谱分析,在放电产物中检测到了硫代硫酸盐、亚硫酸盐以及硫酸盐.深度氧化使得硫离子具有更高的放电容量.与之前研究的燃料相比,硫离子具有成本低、运输容易、电化学活性高并且能够被非贵金属催化剂催化的优点.     

高温固体氧化物燃料电池（SOFC）进展

固体氧化物燃料电池(SOFC) 采用的是全固体的电池结构, 不存在液体电解质带来的腐蚀和流失等问题, 而且具有燃料适应性广等突出优点, 近几年发展非常迅速, 已经展示出作为集中或分散发电新技术的前景。本文较详细地介绍了固体氧化物燃料电池的特点、工作原理和关键电池材料的研制, 并全面阐述了国内外发展现状和发展趋势。     

The effect of mass transfer on electrochemical impedance of a solid oxide fuel cell anode

This paper presents electrochemical impedance simulation of a solid oxide fuel cell (SOFC) anode in order to investigate the effect of mass transport processes on the impedance spectra. The current model takes in to account the gas-phase transport processes both in the gas channel and within the porous electrode and couples the gas transport processes with the electrochemical kinetics. The impedance simulation is carried out in time domain, and the correlation between the anode harmonic responses to the sinusoidal excitation and the impedance spectra is analyzed. In order to solve the system of non-linear equations, an in-house code based on the finite difference method is developed and utilized. Results show a depressed semicircle in the Nyquist plot, which originates from gas transport processes in the gas channel, in addition to a Warburg diffusion impedance originates from gas transport in the thick porous anode. The influence of parameters such as electrode thickness, inlet gas composition, and temperature is also investigated and the results are discussed. The simulation results are in good agreement with published data.     

Development of solid–oxide fuel cell for reduced operating temperatures

A technique for formation of electrolyte thin films with the thickness of 6–10 μm of zirconia stabilized by yttria (YSZ) is developed on the basis of the method of chemical deposition from the vapor phase of organometallic compounds (MOCVD). Planar electrochemical cells based on film electrolyte with a supporting anode with the working surface area of 12 cm² were manufactured. A solid-oxide fuel cell (SOFC) based on two fuel cells was developed and its life cycle tests at reduced operating temperatures (<800°C) were carried out for 400 h. The maximum power density reached in the SOFC tests was 316 mW/cm².     

Catalysis in high-temperature fuel cells

Catalysis plays a critical role in solid oxide fuel cell systems. The electrochemical reactions within the cell--oxygen dissociation on the cathode and electrochemical fuel combustion on the anode--are catalytic reactions. The fuels used in high-temperature fuel cells, for example, natural gas, propane, or liquid hydrocarbons, need to be preprocessed to a form suitable for conversion on the anode-sulfur removal and pre-reforming. The unconverted fuel (economic fuel utilization around 85%) is commonly combusted using a catalytic burner. Ceramic Fuel Cells Ltd. has developed anodes that in addition to having electrochemical activity also are reactive for internal steam reforming of methane. This can simplify fuel preprocessing, but its main advantage is thermal management of the fuel cell stack by endothermic heat removal. Using this approach, the objective of fuel preprocessing is to produce a methane-rich fuel stream but with all higher hydrocarbons removed. Sulfur removal can be achieved by absorption or hydro-desulfurization (HDS). Depending on the system configuration, hydrogen is also required for start-up and shutdown. Reactor operating parameters are strongly tied to fuel cell operational regimes, thus often limiting optimization of the catalytic reactors. In this paper we discuss operation of an authothermal reforming reactor for hydrogen generation for HDS and start-up/shutdown, and development of a pre-reformer for converting propane to a methane-rich fuel stream.     

Determination of H2S and HCl concentration limits in the fuel for anode supported SOFC operation

Solid oxide fuel cell (SOFC) is an electric generator, operating based on electrochemical reaction converting gaseous fuel to electricity and heat. It is characterized by the high electrical efficiency of up to 70% with cogeneration and negligible emission of pollutants. Syngas from the biomass gasification is considered to be a possible fuel for solid oxide fuel cell systems. However, high level of contaminants such as H₂S, HCl, alkali metals, tars and particulates, in addition to possibility of carbon deposition and high temperature gradients due to internal reforming of hydrocarbons requires cleaning and conditioning of the syngas stream. The current status of the effect of contaminants on the SOFC performance has been reviewed and effects of single contaminants (H₂S, HCl) has been tested. It has been found that anode supported solid oxide fuel cell (AS-SOFC) with Ni/YSZ cermet anode can tolerate up to 1 ppm H₂S and up to 10 ppm HCl without significant performance degradation.      

Modeling of microreactor for syngas production by catalytic partial oxidation of methane

Fixed-bed reactors for the catalytic partial oxidation of methane (CPOM) to produce synthesis gas still pose hot spots problems. Microreactor is a good alternative reactor proposed to resolve these problems. In this paper, synthesis gas (hydrogen and carbon monoxide) production was investigated by a two-dimensional numerical model of single microchannel. CFD modeling with detailed chemistry was conducted to understand the CPOM on platinum (Pt) catalyst. Gas inlet velocity, microchannel pressure, and fuel to air ratio (F/A) are selected as the effective parameters on microchannel performance. Study results show that Reynolds number has considerable effect on methane conversion, hydrogen to carbon monoxide ratio (H2/CO), and product distribution. Increasing gas inlet velocity causes all the above parameters to decrease. It is noted that increasing microchannel pressure and decreasing the ratio of fuel to air cause the decrease of the H2/CO ratio.     

Ash-free coal as fuel for direct carbon fuel cell

This work describes the performance of the direct carbon fuel cell (DCFC) fuelled by ash-free coal. Employing coal in the DCFC might be problematic, mainly because of the ash deposition after the cell reactions. In the study, the carbonaceous ash-free component of coal is obtained, which is then evaluated as the DCFC fuel and compared with raw coal, active carbon, carbon black, and graphite. The electrolyte-supported SOFC structure is adapted to build the DCFC. The DCFC based on the ash-free coal fuel exhibits good performance with regard to the maximum power density, day-by-day measurements, and durability at continuous run. When the carbon fuels are internally gasified to H₂ and CO, the power density is generally much improved, compared to N₂ pyrolysis environment. The power generation is most likely related to the concentration of pyrolyzed gases as well as the electrochemical reactivity of the solid carbon.     

新型导电陶瓷Sm_0.9St_0.1Al_0.5Mn_0.5O_(3-δ)的制备及其电性能研究

采用有机凝胶法结合固相烧结技术制备了Sm_0.9St_0.1Al_0.5Mn_0.5O_(3-δ)(SSAM9 155)新犁导电陶瓷.通过TG/DTA,FTIR, XRD,SEM和直流四引线法系统研究了凝胶前驱体的热分解及其相转化过程和烧结体的结构、相稳定性、微观形貌、电导率以及电输运机制.结果表明,凝胶前驱体在900℃焙烧5 h可以形成完全晶化的四方钙钛矿相纳米粉体;高温烧结制得的SSAM9155陶瓷的电导率取决于P型电导,电导率随温度的升高而增大,导电行为符合P型小极化子跳跃机制;随烧结温度的升高或保温时间的延长,SSAM9155陶瓷的电导率和相对密度都先增大后减小,1600℃烧结10 h制得的SSAM9155陶瓷具有最高的电导率和相对密度(98%),该样品在空气和氢气气氛中850℃时的电导率分别为8.21和1.26 S·cm~(-1),表观活化能分别为0.265和0.465 eV.具有较高电导率的Sr,Mn掺杂的SmAlO_3导电陶瓷有望成为一种新型的固体氧化物燃料电池(SOFC)阳极材料.     

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 ) .     

Ni-Fe/SDC电池阳极材料的制备和性能表征

采用硝酸盐-柠檬酸法合成了具有高比表面积的一系列Ni-Fe氧化物和电解质Ce0.8Sm0.2O1.9(SDC), 利用上述材料制备出固体氧化物燃料电池(SOFC)复合阳极材料Ni-Fe/SDC, 并对其微结构和相关性能进行测试. 结果表明: 该复合阳极材料与电解质SDC具有较高的热匹配性, 以其作为SOFC的阳极, 氢气为燃料, 其单电池表现出优异的性能, 700 ℃电池输出功率密度最高可达90.6 mW•cm−2.