Sol-gel synthesis and electrical properties of ceria-based solid electrolytes

A series of solid electrolytes (Ce_(0.8)RE_(0.2))_(1-x)M_xO_(2-δ)(RE: Rare earth, M: Alkali earth) were prepared by sol-gel methods. XRD indicated that a pure fluorite phase was formed at 800℃. The synthesis temperature by the sol-gel methods was about 700℃ lower than by the traditional ceramic method. The electrical conductivity and impedance spectra were measured. XPS showed that the oxygen vacancy increased obviously by doping MO, thus, resulting in the increase of the oxygen ionic transport number and conductivity. The performance of ceria-based solid electrolyte was improved. The effects of RE_2O_3 and MO on the electrical properties were discussed. The conductivity and the oxygen ionic transport number of (Ce_(0.8)Sm_(0.2))_(1-0.05)Ca_(0.05)O_(2(?)δ) is 0.126 S·cm~(-1) and 0.99 at 800℃, respectively.     

Effect of the fuel electrode composition and structure on the performance of the direct methanol fuel cell

The effect the composition and structure of the active layer of the anode exerts on the performance of the solid-polymer direct methanol fuel cell is studied experimentally. It is shown that the ohmic voltage losses in the layer and the content of the solid polymer electrolyte (SPE) play an important role. The performance of the fuel cells is the best at 20–25 vol % SPE in the layer.     

咪唑类离子液体用作电解质对燃料电池性能的影响

为优化改善燃料电池的整体性能,在自由电解质燃料电池中,考察了五种咪唑类离子液体用作燃料电池电解质时对燃料电池性能的影响。结果表明,以氢气为燃料时,在相同电流密度下,电路电压和输出功率从高到低依次为1-丁基-3-甲基咪唑四氟硼酸盐 > 1-丁基-3-甲基咪唑六氟磷酸盐 > 氢氧化钠溶液 >> 氯化-1-丁基-3-甲基咪唑 > 溴化-1-丁基-3-甲基咪唑 > 1-丁基-3-甲基咪唑硫酸氢盐;以甲烷为燃料时,相同电流密度下,电路电压和输出功率从高到低则依次为溴化-1-丁基-3-甲基咪唑 > 1-丁基-3-甲基咪唑硫酸氢盐 > 氯化-1-丁基-3-甲基咪唑 > 氢氧化钠溶液> 1-丁基-3-甲基咪唑四氟硼酸盐 > 1-丁基-3-甲基咪唑六氟磷酸盐。以[Bmim]BF₄为氢气燃料电池电解质时,温度升高和离子液体中水含量增加,均会使燃料电池的性能减弱。     

Synthesis and test of palladium-based nanostructured anodic electrocatalysts for hydrogen fuel cells with solid polymer electrolyte

Palladium-based nanostructured electrocatalysts on the Vulcan XC-72 carbon support for fuel cells with solid polymer electrolyte are synthesized and studied. In particular, electrochemical studies of the synthesized catalysts are carried out and membrane-electrode assemblies are assembled on their basis and tested. The test results indicate that platinum can be replaced with palladium in the hydrogen electrode of the fuel cells.     

固体氧化物燃料电池直接以焦炭为燃料的电性能

直接碳固体氧化物燃料电池（DC-SOFC）是一种潜在的固体碳燃料高效率、低污染发电技术。本研究报道了将工业焦炭直接用作管式DC-SOFC燃料的研究。制备了电极材料为Ag-GDC （钆掺杂氧化铈）的YSZ （钇稳定化氧化锆）电解质支撑型管式固体氧化物燃料电池（SOFC）。采用拉曼光谱、扫描电镜和X射线能谱仪对焦炭燃料进行了性质表征。结果表明,焦炭燃料呈微米级的颗粒状,并含有大量对Boudouard反应有利的缺陷结构。电池以纯焦炭为燃料在850℃取得的最大功率密度为149mW/cm²,在碳燃料表面负载能提高Boudouard反应速率的Fe催化剂后,最大功率密度提高至217mW/cm²。通过电化学测试和尾气表征,分析了恒电流放电过程中电池的性能衰减机制。测试结果证明了将焦炭直接用作全固态DC-SOFC的燃料产生电能的可行性。     

以丁烷为燃料的便携直接火焰固体氧化物燃料电池堆的研究(英文)

以丁烷液化气为燃料,以固体氧化物燃料电池为电源,可以进行全天候的充电,是未来理想的充电模式。研究了以丁烷为燃料的可以便携的直接火焰燃料电池堆。该电池结构和电性能分别用扫描电子显微镜SEM和电化学工作站进行了表征。该电池堆由3片以Ni/YSZ为阳极支撑形的单电池构成。该电池堆操作开路电压为2.1 V,最大输出功率为0.24 W,可带动小风扇连续运行超过4 h。运行4 h后电池阳极没有积炭发生,说明该电池可以连续运行多个小时,可用作便携充电电源。     

Development of new glass composite membranes and their properties for low temperature H2/O2 fuel cells.

A new glass electrolyte formed by constant amounts of titanium oxide (TiO2) and various amount of phosphotungstic acid (PWA) doped P2O5-SiO2 is prepared using the sol-gel process. The structural formation is confirmed by Fourier infrared spectroscopy (FTIR) and from thermogravimetric and differential thermal analysis (TG/DTA) measurements, the glasses display good thermal stability. Further characterisation is undertaken by N2 adsorption/desorption measurements, proton conductivity and hydrogen permeability analyses and a H2/O2 fuel cell test is also performed. The glass materials with large pores and specific surface area are suitable for use as the electrolyte in H2/O2 fuel cells. The effect of TiO2 processing with constant amount of PWA in phosphosilicate glasses, is investigated and discussed. The hydrogen permeability is 1.57x10(-11) mol cm(-1) s(-1) Pa(-1) at 110 degrees C for 0.8 mm thick glass; a power density of 46.3 mW cm(-2) at 125 mA cm(-2) and a current density of 175 mA cm(-2) is obtained (T=28 degrees C, relative humidity).     

Preparation of microtubular solid oxide fuel cells based on highly asymmetric structured electrolyte hollow fibers

A simple and cost-effective method has been developed for the fabrication of microtubular solid oxide fuel cells (MT-SOFCs). Highly asymmetric electrolyte hollow fibers composed of a thin dense skin layer and a thick porous substrate are first prepared by a modified phase inversion/sintering technique. The porous substrate is then formed into the anode by deposition of a Ni catalyst via an electroless plating method inside the pores while the thin dense skin layer serves directly as the electrolyte film of ...     

基于高度非对称结构电解质中空纤维的微管式固体氧化物燃料电池制备

提出了一种简单而方便的微管式固体氧化物燃料电池(MT-SOFCs)的制备新方法.首先应用改进相转化-烧结技术制备由致密电解质表皮薄层和多孔支撑层构成的高度非对称结构电解质中空纤维膜(微管),在电解质中空纤维膜的多孔支撑层内通过化学镀法沉积Ni催化剂作为电池阳极,而致密电解质表皮层直接作为电解质膜,在电解质微管外表面用浆料涂层法制备电池的多孔阴极,烧结后即得到完整的MT-SOFC.应用该方法制备了Ni-YSZ|YSZ|LSCF微管式电池,该电池以H2/空气作原料气,在800℃时最大输出功率达到159.6mWcm-2.     

Active layer of the cathode of a fuel cell with a solid polymer electrolyte: The effect of the Nafion concentration on the overall characteristics

A computer-aided simulation of the structure of the active layer of the cathode of a fuel cell with a solid polymer electrolyte (Nafion) is performed under the assumption about equidimensionalness of dimensions of grains of the substrate (with platinum crystallites in them) and grains (agglomerates of molecules) of Nafion. It is analyzed how the Nafion concentration affects principal parameters, which include the specific surface area, in the vicinity of which electrochemical process goes on; the effective ionic electroconductivity, and the effective diffusion coefficient of a gas. It is demonstrated how one can determine the Nafion concentration at which the overall current takes on a maximum value. Dependences of the optimum value of the overall current and the thickness of the active layer and the weight of platinum, which correspond to it, on the Nafion concentration are calculated. It is demonstrated that there in principle cannot exist one individual optimum concentration of Nafion, which is suitable for all techniques used for the preparation of the active layer. The mutual relationship between values of the effective diffusion coefficient of a gas and the effective ionic electroconductivity of Nafion determines the value of the optimum of the Nafion concentration.     

Mass transfer in porous systems, flooded in part with water, of gas diffusion and catalytic layers of the cathode of a fuel cell with a solid polymer electrolyte

Mass transfer in porous gas diffusion and catalytic layers of the cathode of a hydrogen-air fuel cell with a solid polymer electrolyte is considered. The transport processes are considered with allowance made for the partial flooding of porous systems of these layers with water, which forms during the fuel cell operation. The consideration also allows for the influence of the diluent gas present when air oxygen is used as the oxidant. The fraction of water-flooded pores is calculated within percolation theory as a function of structural parameters of the porous system. Conditions leading to the beginning of the gas diffusion layer flooding are presented.     

Nanostructure and properties of sulfonated polyarylenethioethersulfone copolymers as proton exchange fuel cell membranes

A systematic investigation of properties and nanostructure of sulfonated polyarylenethioethersulfone (SPTES) copolymer proton exchange membranes for fuel cell applications has been presented. SPTES copolymers are high temperature resistant (250 °C), and form tough films with excellent proton conductivity up to 170 ± 5 mS/cm (SPTES 70 @ 85 °C, 85%RH). Small angle X‐ray scattering of hydrated SPTES 70 revealed the presence of local water domains (diameter ～5 nm) within the copolymer. The high proton conductivity of the membranes is attributed to the formation of these ionic aggregates containing water molecules, which facilitate proton transfer. AFM studies of SPTES 70 as a function of humidity (25–65%RH) showed an increase in hydrophilic domains with increasing humidity at 22 °C. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2813–2822, 2007     

Influence of preparation method on the structure and catalytic activity of supported solid sulfuric acid

Summary FT-IR and ²⁹Si-NMR studies suggested the interaction of H₂SO₄ with the SiO₂ support in the material synthesized by the sol-gel method. ¹H-NMR results showed that the acid strength of solid sulfuric acid was almost the same as that of liquid sulfuric acid. The catalyst showed higher catalytic activity and stability than that prepared by impregnation method.     

SOFC中干甲烷浓度对Ni-YSZ阳极上反应的影响

为探讨固体氧化物燃料电池(solid oxide fuel cell, SOFC)中干甲烷浓度对反应的影响,采用色谱在线测量阳极尾气,总结阳极尾气的变化规律。在此基础上,分析干甲烷在固体氧化物燃料电池Ni-YSZ阳极上的反应,寻找干甲烷浓度与电流对电池阳极反应影响的数学关系。结果表明,随着电流密度的增加,低浓度甲烷按顺序发生CH₄+O^2- → CO+2H₂+2e^-、CH₄+2O^2- → CO+H₂O+H₂ +4e^-、CH₄+3O^2- → CO+2H₂O + 6e^-、CH₄+4O^2- → CO₂+2H₂O+8e^-反应,高浓度甲烷只发生甲烷的第一个氧化反应,中浓度甲烷发生前两个或前三个反应。依据法拉第第一定律及反应物之间的关系,确定甲烷的低、中、高浓度的判定依据分别为:q_v(CH₄)≤I/(4F)、I/(4F)≤q_v(CH₄)≤I/(2F)、q_v(CH₄)≥I/(2F)。     

薄膜型中温固体氧化物燃料电池 (SOFC)研制及性能考察

用一种廉价的湿化学方法 ,在Ni_YSZ阳极基膜上制备出致密的YttriaStabilizedZirconia(YSZ)薄膜 .薄膜的厚度约为 10 μm ,致密均匀 ,无裂纹等缺陷 .以Ni_YSZ阳极基膜 ,YSZ薄膜和锶掺杂锰酸镧阴极 (LSM )组装的SOFC单电池 ,在 80 0℃下功率密度达 0 1W /cm2 .研究分析表明 ,YSZ薄膜的IR降 (包括电极 /YSZ薄膜的接触电阻 )较小 ,不是影响电池性能的主要因素 ,大的阳极过电位是影响电池性能的主要因素 .     

Critical challenges and progress of solid garnet electrolytes for all-solid-state batteries

Significant safety problems and poor cyclic stability of conventional lithium-ion batteries, which based on organic liquid electrolytes, hinder their practical application, while all-solid-state batteries (ASSBs) are considered the most promising candidates to replace traditional lithium-ion batteries. As a critical component of ASSBs, solid-state electrolytes play an essential role in ion transport properties and stability. At present, the solid garnet electrolyte is considered as one of the most promising electrolytes because of its excellent performance. However, it still faces many challenges in ionic conductivity, air stability, electrode/electrolyte interface, and lithium dendrites. Therefore, this review is concerned about the up-to-date progress and challenges which will greatly influence the large-scale application of solid garnet electrolytes. Firstly, various ways to improve the ionic conductivity of solid garnet electrolytes are comprehensively summarized. Then, the stability of solid garnet electrolytes in the air is carefully discussed. Secondly, the latest progress in interface engineering between anode/cathode and solid garnet electrolytes treated by different methods is reported. The formation mechanism and influencing factors of lithium dendrites in the solid garnet electrolyte are systematically focused on. Finally, the development and innovation of composite solid garnet electrolytes and 3D garnet electrolytes are summarized in detail. Some important characterization techniques for studying the aforementioned problems are also summarized. Based on the current development of solid garnet electrolytes and solid-state batteries, further challenges and perspectives are presented.     

BaCe_(0.8)Y_(0.2)O_(3-α)固体电解质的离子导电性及其燃料电池性能

用高温固相反应合成了BaCe0.8Y0.2O3-α固体电解质用氢浓差电池和氧浓差电池方法研究了它的离子导电特性。以该氧化物为固体电解质多孔性Pt为电极材料组成氢空气燃料电池测定了该燃料电池的电流电压特性。研究发现BaCe0.8Y0.2O3-α在氢气中几乎是一个纯的质子导体在氧气中是一个氧离子和电子空穴的混合导体其燃料电池的开路电压OCV接近于理论值最大输出电流密度约为820mA·cm-21000℃最大输出功率密度约为200mW·cm-21000℃放电性能稳定具有良好的电池性能。     

Preparation and characterization of pva based solid polymer electrolytes for electrochemical cell applications

Solid polymer electrolyte films containing poly(vinyl alcohol) (PVA) and magnesium nitrate (Mg(NO3)2) were prepared by solution casting technique and characterized by using XRD, FTIR, DSC and AC impedance spectroscopic analysis. The amorphous nature of the polymer electrolyte films has been confirmed by XRD. The complex formation between PVA and Mg salt has been confirmed by FTIR. The glass transition temperature decreases with increasing the Mg salt concentration. The AC impedance studies are performed to evaluate the ionic conductivity of the polymer electrolyte films in the range of 303 383 K, and the temperature dependence seems to obey the Arrhenius behavior. Transport number measurements show that the charge transport is mainly due to ions. Electrochemical cell of configuration Mg/(PVA + Mg(NO3)2) (70:30)/(I2 + C + electrolyte) has been fabricated. The discharge characteristics of the cell were studied for a constant load of 100 kΩ.     

中温燃料电池阴极材料la0.6sr0.4fe0.8co0.2o3的合成与性能

固体氧化物燃料电池;阴极材料;溶胶-凝胶法     

Mechanical endurance of polymer electrolyte membrane and PEM fuel cell durability

The life of proton exchange membrane fuel cells (PEMFC) is currently limited by the mechanical endurance of polymer electrolyte membranes and membrane electrode assemblies (MEAs). In this paper, the authors report recent experimental and modeling work toward understanding the mechanisms of delayed mechanical failures of polymer electrolyte membranes and MEAs under relevant PEMFC operating conditions. Mechanical breach of membranes/MEAs in the form of pinholes and tears has been frequently observed after long‐term or accelerated testing of PEMFC cells/stacks. Catastrophic failure of cell/stack due to rapid gas crossover shortly follows the mechanical breach. Ex situ mechanical characterizations were performed on MEAs after being subjected to the accelerated chemical aging and relative humidity (RH) cycling tests. The results showed significant reduction of MEA ductility manifested as drastically reduced strain‐to‐failure of the chemically aged and RH‐cycled MEAs. Postmortem analysis revealed the formation and growth of mechanical defects such as cracks and crazing in the membranes and MEAs. A finite element model was used to estimate stress/strain states of an edge‐constrained MEA under rapid RH variations. Damage metrics for accelerated testing and life prediction of PEMFCs are discussed. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2346–2357, 2006