A thermally self-sustained micro solid-oxide fuel-cell stack with high power density

High energy efficiency and energy density, together with rapid refuelling capability, render fuel cells highly attractive for portable power generation. Accordingly, polymer-electrolyte direct-methanol fuel cells are of increasing interest as possible alternatives to Li ion batteries. However, such fuel cells face several design challenges and cannot operate with hydrocarbon fuels of higher energy density. Solid-oxide fuel cells (SOFCs) enable direct use of higher hydrocarbons, but have not been seriously considered for portable applications because of thermal management difficulties at small scales, slow start-up and poor thermal cyclability. Here we demonstrate a thermally self-sustaining micro-SOFC stack with high power output and rapid start-up by using single chamber operation on propane fuel. The catalytic oxidation reactions supply sufficient thermal energy to maintain the fuel cells at 500-600 degrees C. A power output of approximately 350 mW (at 1.0 V) was obtained from a device with a total cathode area of only 1.42 cm2.     

Ba0．5Sr0．5Co0．2Fe0．8O3—δ阴极材料制备与性能表征

采用凝胶浇注法（gelcasting）合成了中温固体氧化物燃料电池阴极材料Ba0.5Sr0．5Co0．2Fe0．8O3-δ粉体。对BSCF粉末和烧结体的性能进行了测试分析。结果表明,制备的试样为单一钙钛矿相,其颗粒尺寸均匀,BSCF阴极材料的电导率随测试温度的升高而降低,其中Ba0．5Sr0．5Co0.2Fe0．8O3-δ在500℃电导率为25．4S／cm。Ba0.5Sr0．5Co0.2Fe0．8O3-δ与SDC的界面阻抗在800℃为0．20Ωm2。     

Studies on the effects of pre-firing and sintering temperature on NSDC nanocomposite electrolytes

Solid oxide fuel cells (SOFCs) technology, with fuel flexibility, is one of the most promising power generation technology. However, the high operating temperature of SOFCs has hindered their commercial applications. As a crucial requirement to enhance its performance, SOFCs electrolytes should operate at a low temperature. Carbonate/ceria composites are developed as electrolytes for low operating temperature SOFCs, and a better understanding of the mechanism of its ionic conductivity serves this purpose. In this work, ceria-carbonate composite electrolyte, Na₂CO₃/samarium doped ceria (NSDC) were synthesized by the co-precipitation method. The synthesized electrolytes were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV–Vis spectroscopy. The XRD and SEM results showed that the sintered NSDC nanocomposite comprised a single-phase dense electrolyte structure. The crystallite size of the NSDC nanocomposite was greatly affected by the different pre-firing temperatures and different sintering temperatures. Also, the ionic conductivity of the prepared NSDC nanocomposite electrolytes was strongly dependent on the pre-firing and sintering temperatures. The NSDC nanocomposite electrolytes were pre-fired at 950 ?°C and 650 ?°C and sintered at 1200 ?°C and 900 ?°C respectively, had ionic conductivity in H₂ and air high as 0.36 ?S/cm and 0.3 ?S/cm.     

Li2SO4质子传导膜H2S固体氧化物燃料电池研究

制备和研究了具有H2S,(MoS2 NiS Ag)/Li2SO4 Al2O3/(NiO Ag),air结构的H2S固体氧化物燃料电池用于产生电能和脱除燃料气体中的H2S.电池在600～650 ℃和大气压下运行.燃料电池的电化学性能受电解膜的组成,电极材料和操作温度影响.掺杂了Al2O3 和少量H3BO4的Li2SO4质子传导膜可以提高膜的机械强度和性能,改善膜的致密性和电池的性能.适宜的Li2SO4 和 Al2O3 比为3～4∶1(质量比), 适宜掺杂H3BO4的量为2%～5%(w).掺杂了Ag粉和电解质的金属硫化物复合阳极在H2S气流下很稳定和性能很好, 掺杂了Ag粉和电解质的的NiO复合阴极在去除H2S时性能优于Pt电极催化剂.在650 ℃电池的最大输出功率密度为70 mW·cm -2,最大电流密度为180 mA·cm -2.然而,电池长期运行的稳定性实验仍有待研究.     

The Composite Cathode of Ag and LSCF for SOFC Working under Intermediate Temperature

1 Introduction The composite electrode of La0.6Sr0.4Co0.2Fe0.8O3(LSCF) and Ag was studied as a new air electrode system for reduced-temperature SOFCs.The LSCF/Ag composite electrodes were prepared by baking the LSCF electrode with various Ag solution infiltrated in the pores of the electrode.In all cases,the cathode polarization resistance was reduced,which may be brought from the catalytic activity of Ag metal.For example,the power density of LSCF electrode on anode supported cell was increased from 0....     

Catalytic performance of nano-hybrid graphene and titanium dioxide modified cathodes fabricated with facile and green technique in microbial fuel cell

Finite resources of the world''s fossil fuel give rise to the irresistible urge to explore alternative renewable energy routes such as microbial fuel cells (MFCs). The limited productivity is one of the main obstacles for MFC scalability. In this study, a dual-chamber MFC was assembled and equipped with fabricated modified cathodes with titanium dioxide (TiO2) or hybrid graphene (HG) which mainly improved the catalytic activity of the cathode. The graphite paste (GP) bare electrode was modified by both nanomaterials using a green and facile technique. The results showed that the modified cathodes resulted in a considerable improvement for the MFC performance, i.e., the power density reaching levels of 80 mW/m2 for GP-TiO2 and 220 mW/m2 for GP-HG compared to 30 mW/m2 for GP electrode. Additionally, the modified electrodes exhibited lower charge transfer resistance (Rct) compared to the bare electrode. Therefore, these modified electrodes, fabricated by an eco-friendly method, could be used as alternatives to the precious expensive metals like Pt.     

中温固体氧化物燃料电池双钙钛矿PrBaCo2O5+δ作为潜在阴极的电化学性能研究

通过溶胶-凝胶制备双钙钛矿PrBaCo_2O_(5+δ)(PBCO)中温固体氧化物燃料电池阴极材料,研究结果表明:PrBaCo_2O_(5+δ)为四方结构.在100~850℃内,PBCO样品为金属导电机制.交流阻抗谱的测试结果表明:PrBaCo_2O_(5+δ)电极在800℃时的极化电阻为0.034 8Ω·cm~2.采用La_(0.9)Sr_(0.1)Ga_(0.8)Mg_(0.2)O_(3-δ)(LSGM)电解质为支撑体的单电池在800℃时的功率密度达到558.7 m W/cm2.     

A class of non-precious metal composite catalysts for fuel cells

Fuel cells, as devices for direct conversion of the chemical energy of a fuel into electricity by electrochemical reactions, are among the key enabling technologies for the transition to a hydrogen-based economy. Of several different types of fuel cells under development today, polymer electrolyte fuel cells (PEFCs) have been recognized as a potential future power source for zero-emission vehicles. However, to become commercially viable, PEFCs have to overcome the barrier of high catalyst cost caused by the exclusive use of platinum and platinum-based catalysts in the fuel-cell electrodes. Here we demonstrate a new class of low-cost (non-precious metal)/(heteroatomic polymer) nanocomposite catalysts for the PEFC cathode, capable of combining high oxygen-reduction activity with good performance durability. Without any optimization, the cobalt-polypyrrole composite catalyst enables power densities of about 0.15 W cm(-2) in H2-O2 fuel cells and displays no signs of performance degradation for more than 100 hours. The results of this study show that heteroatomic polymers can be used not only to stabilize the non-precious metal in the acidic environment of the PEFC cathode but also to generate active sites for oxygen reduction reaction.     

固体氧化物燃料电池电解质用离子导体

固体氧化物燃料电池以其高的能量转换效率和清洁的发电而被广泛研究.其中电解质—离子导体材料是影响固体燃料电池的效率和热力学稳定性的关键.作为所期望的电解质材料应满足以下要求(1)高的离子导电,(2)低的电子导电,(3)在使用条件一热力学稳定,(4)好的综合力学性能.在一些荧石相关结构和钙钛矿塑结构的氧化物中通过掺杂和取代形成氧空位可得到高的氧离子导电性.本文介绍了一些这类离子导体材料,并讨论了它们的特性.     

一种以H2S为燃料的固体氧化物燃料电池

研究了在一个大气压和750～850℃下,具有H2S、(MoS2 NiS Ag)／YSZ／Pt和空气结构的固体氧化物燃料电池的电化学性能,发现升温有助于增强电解质的离子传导性,使电池性能变好．在750℃下,阳极通入H2S、阴极通入空气时,电池的最大电流密度和最大功率密度分别达800mA／cm^2和84mW／cm^2;在850℃下,电池的最大电流密度和功率密度分别达1750mA／cm^2和200mW／cm^2．     

聚苯胺修饰阴极对沉积型微生物燃料电池产电性能的影响

考察了聚苯胺（PANI）修饰阴极对沉积型微生物燃料电池（SMFC）产电性能和有机质去除率的影响。衰减全反射红外光谱（ATR）表征证明修饰电极表面PANI为导电的质子掺杂状态。电化学阻抗谱（EIS）测试揭示,PANI修饰电极的欧姆内阻（R‰）和电荷转移内阻（R。）明显低于空白电极,且随着PANI负载量的增大逐渐减小。以PANI修饰阴极序批式运行沉积型微生物燃料电池（SMFC）,可以显著提高SMFC的产电性能以及沉积物中有机质去除率。与空白阴极SMFC体系相比,PANI—110修饰阴极SMFC的最大功率密度增大了64倍,表观内阻减小了12倍,SCOD去除率由12．4％增大到40．3％。     

Pt-SnO2/C电催化剂异型直接乙醇燃料电池的性能

以掺杂石墨粉的中间相碳微球(MCMB/G)烧结管为阴极支撑体,采用浸涂工艺分别制备了扩散层和催化层,通过在其外表面包裹Nafion 117膜制得管状异型阴极并组装成异型直接乙醇燃料电池,采用水热乙二醇制备了适用于直接乙醇燃料电池的阳极电催化剂,并通过XRD,TEM和EDS等技术对其进行了表征.采用线性循环伏安曲线、交流阻抗等测试手段,对Pt-SnO2/C电催化剂异型直接乙醇燃料电池进行了性能测试,并考察了温度、氧气流量等对电池极化性能的影响.结果表明:异型电池阻抗大于传统的平板电池,但其活化后电池阻抗明显下降;较高的氧气流量和较高的工作温度有利于提高电池性能;60℃条件下,Pt-SnO2/C电催化剂异型直接乙醇燃料电池功率密度达到8.5 mW·cm-2.     

Solid acids as fuel cell electrolytes

Fuel cells are attractive alternatives to combustion engines for electrical power generation because of their very high efficiencies and low pollution levels. Polymer electrolyte membrane fuel cells are generally considered to be the most viable approach for mobile applications. However, these membranes require humid operating conditions, which limit the temperature of operation to less than 100 degrees C; they are also permeable to methanol and hydrogen, which lowers fuel efficiency. Solid, inorganic, acid compounds (or simply, solid acids) such as CsHSO4 and Rb3H(SeO4)2 have been widely studied because of their high proton conductivities and phase-transition behaviour. For fuel-cell applications they offer the advantages of anhydrous proton transport and high-temperature stability (up to 250 degrees C). Until now, however, solid acids have not been considered viable fuel-cell electrolyte alternatives owing to their solubility in water and extreme ductility at raised temperatures (above approximately 125 degrees C). Here we show that a cell made of a CsHSO4 electrolyte membrane (about 1.5 mm thick) operating at 150-160 degrees C in a H2/O2 configuration exhibits promising electrochemical performances: open circuit voltages of 1.11 V and current densities of 44 mA cm-2 at short circuit. Moreover, the solid-acid properties were not affected by exposure to humid atmospheres. Although these initial results show promise for applications, the use of solid acids in fuel cells will require the development of fabrication techniques to reduce electrolyte thickness, and an assessment of possible sulphur reduction following prolonged exposure to hydrogen.     

Sm2O3掺杂Ce2O3的加入量对YBa2Cu3O7-δ界面性能的影响

固体氧化物燃料电池(SOFC)具有稳定性高、寿命长、污染低等优点,是二十一世纪的绿色能源之一。当前SOFC阴极通常采用掺杂的ABO3钙钛矿型材料。这类材料在高温下具有较高的导电率和催化活性,但中温化是SOFC的趋势,高温下常用的La(Sr)MnO3阴极材料在中温下性能下降,不能满足中温下电导率的要求。本论文尝试采用柠檬酸燃烧法来制备YBa2Cu3O7-δ,并在YBCO中加入一定量的Sm2O3掺杂的Ce2O3(SDC)作为SOFC的阴极材料,通过对阻抗分析,研究了SDC掺杂量、烧结温度等对该阴极材料性能的影响。实验结果表明:随着SDC的掺杂量x(0≤x≤50%)和烧结温度的升高,阴极材料的界面阻抗减小。在SDC的掺杂量为50%时,且在800℃下烧结得到的烧结体界面阻抗最小,其界面比电阻仅为0.1353ohm/cm2(800℃),这标志着掺杂SDC的YBCO作为中温固体氧化物燃料电池的阴极材料时非常具有发展前景的。     

空气阴极微生物燃料电池处理模拟酸性矿井水的研究

酸性矿井水因pH值低、重金属离子含量高,难以直接采用硫酸盐还原菌生化处理.试验构建了空气阴极微生物燃料电池系统来处理酸性矿井水,有效处理废水H+和重金属离子,同时还能产电.构建的空气阴极微生物燃料电池系统(污泥量40mL,硫酸盐还原菌30mL,阳极材料为碳布,室温)的最大功率密度达到82.24mW/m2,最大电压为332.2mV;硫酸根的最大去除率达到41.6,对Zn2+、Cu2+、Cd2+和Fe2+的去除率分别达到83.7%、77.4%、84.2%和66.8%,化学需氧量的最大去除率达到60.9%.分析认为,空气阴极微生物燃料电池有效处理废水H+,弱化了H2S的生物抑制作用,强化了硫酸盐还原菌还原产生的S2-与重金属离子生成硫化物,并经能谱分析加以验证.     

H2S气体浓度及流率对复合质子传导膜燃料电池性能的影响

采用溶胶—凝胶法制备了纳米级Li2SO4+Li2WO4+Al2O3复合质子传导膜,研究了不同H2S气体浓度、流率和操作温度对结构为H2S、（复合MoS2阳极催化剂）/ 复合质子传导膜/（复合NiO阴极催化剂）、空气的燃料电池电化学性能影响。燃料电池的性能与通入阳极侧的H2S浓度和流率有关,H2S浓度和流率增加,提高了阳极侧气体扩散速率和电化学活性组分,使燃料电池的开路电压、输出电流与功率密度提高,电化学性能变好。即使气体中的H2S浓度低达5%时,该气体也可作为电池的燃料并用来发电。操作温度增加,质子传导膜的电传导率和电化学反应速率增加,电池的输出电流与功率密度提高。比较了MoS2与复合MoS2催化剂的性能,复合MoS2催化剂比MoS2催化剂具有更好的性能和化学稳定性。当采用纯H2S作为燃料,通入阳极和阴极侧的H2S和空气的流率分别为35mlmin-1和100mlmin-1,操作温度为650、700和750oC时,燃料电池产生的最大功率密度为12.4、52.9和130 mWcm-2、最大电流密度为45、281和350 mAcm-2。     

Effect of La0.8Sr0.2Co0.2Fe0.8O3-δ morphology on the performance of composite cathodes

In the present work,one dimensional La0.8Sr0.2Co0.2Fe0.8O3 δ(LSCF) nanofibers with the mean diameter of about 100 nm prepared by electrospinning were deposited on Gd0.2Ce0.8O1.9(GDC) electrolyte followed by sintering to form one dimensional LSCF nanofiber cathode. And LSCF/GDC composite cathodes were formed by introducing GDC phases into LSCF nanofiber scaffold using infiltration method. The polarization resistances for the composite cathode with an optimal LSCF/GDC mass ratio of 1/0.56 are 0.27,0.14 and 0.07 Ω cm2at 650,700 and750 1C,respectively,which are obviously smaller than 2.26,0.78 and 0.29 Ω cm2of pure LSCF nanofiber cathode. And the activation energy is1.194 eV,which is much lower than that of pure LSCF nanofiber cathode(1.684 eV). These results demonstrate that the infiltration of GDC into LSCF nanofiber scaffold is an effective approach to achieve high performance cathode for solid oxide fuel cells(SOFCs). In addition,the performance of composite cathode in this work was also compared with that of our previous nanorod structured LSCF/GDC composite cathode.     

Nitrogen-doped graphene nanosheets as high efficient catalysts for oxygen reduction reaction

It is of great significance in exploring alternative catalysts to platinum (Pt)-based materials for oxygen reduction reaction (ORR),because this reaction is invariably involved in various fuel cells and metal-air batteries.We herein reported the nitrogen doped graphene nanosheets (NGNSs) with pore volume of as high as 3.42 m 3 /g and investigated their potential application as ORR catalysts,it was demonstrated the NGNSs featured high activity,improved kinetics and excellent long-term stability for ORR.The NGNSs were successfully used as cathode catalysts of microbial fuel cells (MFCs) and performed even better than the commercial Pt/C (Pt 10%) catalysts at the maximum power output.     

Designing fast oxide-ion conductors based on La2Mo2O9

The ability of solid oxides to conduct oxide ions has been known for more than a century, and fast oxide-ion conductors (or oxide electrolytes) are now being used for applications ranging from oxide fuel cells to oxygen pumping devices. To be technologically viable, these oxide electrolytes must exhibit high oxide-ion mobility at low operating temperatures. Because of the size and interaction of oxygen ions with the cationic network, high mobility can only be achieved with classes of materials with suitable structural features. So far, high mobility has been observed in only a small number of structural families, such as fluorite, perovskites, intergrowth perovskite/Bi2O2 layers and pyrochlores. Here we report a family of solid oxides based on the parent compound La2Mo2O9 (with a different crystal structure from all known oxide electrolytes) which exhibits fast oxide-ion conducting properties. Like other ionic conductors, this material undergoes a structural transition around 580 degrees C resulting in an increase of conduction by almost two orders of magnitude. Its conductivity is about 6 x 10(-2) S cm(-1) at 800 degrees C, which is comparable to that of stabilized zirconia, the most widely used oxide electrolyte. The structural similarity of La2Mo2O9 with beta-SnWO4 (ref. 14) suggests a structural model for the origin of the oxide-ion conduction. More generally, substitution of a cation that has a lone pair of electrons by a different cation that does not have a lone pair--and which has a higher oxidation state--could be used as an original way to design other oxide-ion conductors.     

基于钛网基膜电极组件的被动式直接甲醇燃料电池

基于钛网基膜电极组件（membrane electrode assembly,MEA）设计并制作被动式直接甲醇燃料电池（directmethanol fuel cell,DMFC）．钛网基MEA以钛金属网作为电极支撑体基底材料,Nafionll7作为质子交换膜．PtRU／XC-72R作为阳极催化剂,Pt／XC-72R作为阴极催化剂．被动式DMFC壳体采用有机玻璃材料制作．密封元件采用硅胶片制作．紧固件选用标准件．在室温空气自呼吸条件下,选取不同甲醇浓度的电解液．测试了基于钛网基MEA的被动式DMFC极化性能．结果表明：当电解液中甲醇浓度从0．5mol／L经过1．0mol／L增大到1．5mol／L时．基于钛网基MEA的被动式DMFC的功率密度峰值呈现先增大、后减小的规律;当甲醇浓度为1．0mol／L。电池功率密度峰值为3．91mW/cm2．