Ni-YSZ|YSZ|LSM固体氧化物燃料电池性能测试

研究出平板式Ni-YSZ|YSZ|LSM单体电池；设计组装了电池性能测试系统；以H2为燃料，O2为氧化剂气体，在温度为500－900℃时测试了电池开路电压随温度和燃料气体流量变化而变化的对应关系；并分析了变化的原因，同时考察了电流电压特性和电流功率特性，发现电池的输出电流和输出功率随温度的升高而明显提高。     

液相进料直接甲醇燃料电池性能的实验研究

利用美国Arbin公司燃料电池测试装置，对液相进料直接甲醇燃料电池的性能进行了实验研究。通过电流．电压曲线，研究了燃料电池工作温度和压力、阴阳极差压、甲醇和氧气流量、甲醇浓度等参数对电池性能的影响。实验结果表明：较高的电池温度可以提高电池的性能；阴阳极差压提高，电池性能降低；在甲醇浓度较低时，燃料电池工作压力、工质流量和浓度的增加均使燃料电池性能有不同程度的提高。图8参7     

国内外能源信息

日本夏普公司最近研制出转换效率高达16.4％的多晶硅太阳能电池。这种电池面积10平方厘米,电极与电池成直角,以减少电阻和增加输出电流。为减少损失,电池表面增涂西层反射光膜。到1992年,多晶硅太阳能电池的光电转换率可望达到18％。     

氮化硅薄膜的性能研究以及在多晶硅太阳电池上的应用

利用椭圆偏振仪、准稳态光电导衰减法(QSSPCD)、X射线光电子能谱(XPS)、红外吸收光谱(IR)、反射谱等手段，研究了不同硅烷和氨气配比条件以及沉积温度对在多晶硅太阳电池上所沉积的氮化硅薄膜性能的影响，优化了沉积条件。通过比较沉积前后电池的各项性能，确认经氮化硅钝化后电池效率提高了40％以上，电池的短路电流也提高了30％以上，对于电池的开路电压提高也很大.     

高开路电压高转换效率硅太阳电池研究

一、引言 在改善硅太阳电池性能的研究中,为提高电池的短路电流已做了大量工作。例如,紫电池、绒面电池及锯齿形盖片的研制,已将电池的短路电流密度提高到47.5mA/cm~2以上。近期内,人们把提高电池的开路电压作为主攻方向,并已进行了多方面的努力。然而,报道的制造工艺都较复杂,周期也较长。另一方面,所有“高压”电池的短路电流输出几乎都比通常     

酞菁铜衍生物LB膜／N—Si光伏电池的反常的二极管整流效应

从表面态和材料电阻率的角度分析了酞菁铜衍生物ＬＢ膜光伏电池的反常整流效应，讨论了该效应与光生电流的关系，并介绍了消除反常现象提高光生电流的实验方法。     

硅基薄膜叠层太阳能电池减反射膜的效果评估

减反射膜涂覆在硅基薄膜太阳能电池的前板玻璃表面,通过减少对太阳光的反射而提高光电转换效率;然而,减反射膜的热固化工艺会影响减反射膜的最终效果,而无法区分减反射作用和热固化过程对电池效率的影响。文章设计了一种简单有效的评估测试方法,即将未镀减反膜的玻璃和镀减反膜的玻璃分别与电池叠放,来测试电池的量子效率和电流-电压性能,排除热固化工艺对电池性能的影响,以了解减反射膜对电池的作用效果。     

酞菁铜衍生物LB膜／N－Si光伏电池的反常二极管整流效应

从表面态和材料电阻率的角度分析了酞菁铜衍生物ＬＢ膜光伏电池的反常整流效应，讨论了该效应与光生电流的关系，并介绍了消除反常现象提高光生电流的实验方法。     

温度、压力和湿度对质子交换膜燃料电池性能的影响

以Nafion质子交换膜燃料电池(PEMFC)为对象，通过测量电池的电流—电压、电流—功率和电压—时间曲线，研究了温度、压力和湿度等条件对电池性能的影响，同时也考察了电池的能量转换效率及短期运行时的稳定性，得出了电池较佳的工作条件。实验和计算结果表明：在反应温度为72℃、H2和02压力分别为0．2MPa、进气湿度饱和时，电池最大输出功率可达0．7W．cm^-2；在0．3W.cm^-2～0．7W．cm^-2范围内电池能量转换效率为62％—34％；在大电流密度下电池仍能稳定工作。     

染料敏化太阳电池中电子传输性能

通过检测染料敏化TiO2纳米晶太阳电池中TiO2膜厚度和入射光的强度对电池光电转换性能的影响来研究电池中电子的传输性能。结果表明：TiO2膜厚度和入射光强度对电池性能有很大的影响。当TiO2膜厚度增大时，电池的短路电流(Isc)加大，而填充因子(ff)下降，开路电压(Voc)先上升后下降，电池的单色光光电转化效率(IPCE)增大；当光强度加大时，电池的短路电流和开路电压均增加，但是电池的填充因子降低。并用UV-Vis等手段表征了染料RuL2(SCN)2。     

Comparison of different current collecting modes of anode supported micro-tubular SOFC through mathematical modeling

A two-dimensional model comprising fuel channel, anode, cathode and electrolyte layers for anode-supported micro-tubular solid oxide fuel cell (SOFC), in which momentum, mass and charge transport are considered, has been developed. By using the model, tubular cells operating under three different modes of current collection, including inlet current collector (IC), outlet current collector (OC) and both inlet and outlet collector (BC), are proposed and simulated. The transport phenomena inside the cell, including gas flow behavior, species concentration, overpotential, current density and current path, are analyzed and discussed. The results depict that the model can well simulate the diagonal current path in the anode. The current collecting efficiency as a function of tube length is obtained. Among the three proposed modes, the BC mode is the most effective mode for a micro-tubular SOFC, and the IC mode generates the largest current density variation at z-direction.     

Dependence of open-circuit potential and power density on electrolyte thickness in solid oxide fuel cells with mixed conducting electrolytes

A continuum-level electrochemical model previously developed by the authors [1] is used to investigate the dependence of open-circuit voltage (OCV), and maximum power density on electrolyte thickness for solid oxide fuel cells (SOFCs) with mixed conducting electrolytes. Experimental results confirm the models predictions that OCV decreases monotonically with decreasing electrolyte thickness due to increased permeation flux [1]. The model was further extended to show that there exists an optimal electrolyte thickness at which maximum power density occurs for mixed conducting electrolytes. As expected, for electrolyte thickness greater than optimal losses from ohmic overpotential reduce cell output. However, when the electrolyte thickness is lower than optimal losses from an increasing electronic “leakage” current reduce cell output.     

Ag current collector for honeycomb solid oxide fuel cells using LaGaO3-based oxide electrolyte

Honeycomb type solid oxide fuel cell (SOFC) using a Ag mesh as a current collector and La_0.9Sr_0.1Ga_0.8Mg_0.2O₃ (LSGM) as an electrolyte was studied for reducing production cost. When an Ag mesh was used as a current collector, the power density of the cell became lower than that of a cell using a Pt mesh due to the relatively worse contact caused by the lower calcination temperature, particularly in the case of the anode. The preparation method and the electrode structure were investigated for the purpose of increasing the power density of the cell using the Ag current collector. It was found that an interlayer of Ni–Sm_0.2Ce_0.8O_1.9 (1:9) between the NiFe–LSGM cermet anode and the LSGM electrolyte was effective for decreasing the pre-calcination temperature for anode fabrication. Much higher power densities of 300 mW cm⁻² and 140 mW cm⁻² at 1073 K and 973 K, respectively, were achieved by inserting an interlayer. These results for the power density of the cell using the Ag mesh current collector after the optimization of the electrode structure and the preparation procedure are close to those of the cell using the Pt mesh current collector cell presented in our previous work.     

Study on the levelling process of the current collector for the molten carbonate fuel cell based on curvature integration method

The current collector for the molten carbonate fuel cell (MCFC) is manufactured from the sheet metal forming process. After the forming process, the current collector is bent resulting in a specific curvature (κ_i) in the direction in which trapezoidal protrusions are formed due to springback. In the stack of the MCFC, small deformation of the current collector can bring about defects in the electrolyte, non-uniform contact and difficulties in assembling the stack. Therefore, the curvature of the current collector should be minimized in order to reduce defects which can cause critical damage in the long-term operation. In order to straighten the current collector, the levelling process using three rolls was employed. In this work, a simple and effective method for designing the levelling process was proposed. An analytic model and the finite element analysis were used in combination. The optimal curvature minimizing the resultant curvature and the resultant moment of the current collector down to zero was calculated from the bending moment–curvature relationship. The bending moment–curvature relationship of the current collector was determined from the finite element analysis of uniform bending using the simulation results of the three-stage forming process. In the analytic model based on curvature integration method, the proper roll arrangement corresponding to the optimal curvature was calculated. Experiments were conducted using the calculated roll arrangement. The current collector was levelled nearly flat using the levelling process. After the levelling process, the flattened current collector was easily assembled with a centre plate and ensuring uniform contact with the electrolyte.     

Experimental investigation of the effect of free openings of current collectors on a direct methanol fuel cell

A current collector is one of the key components of a direct methanol fuel cell (DMFC). For a planar-type DMFC, the current collector is usually fabricated from a thin metal that has open holes. The geometry of the current collector may have a significant effect on DMFC performance. Therefore, the design of the current collector is important for DMFC design. The objective of this study is to make a systematic experimental investigation of DMFC performance in the presence of current collectors with different free open ratios and total perimeter lengths of the free openings. Current collectors with 5 × 5, 7 × 7, and 10 × 10 hole arrangements under different total free open ratios of 30%, 40%, 50%, and 60% are investigated. The results show that the total free open ratio can significantly affect cell performance; they also show that decreasing the total free open ratio decreases cell performance, and increasing the total free open ratio increases cell performance. A high total free open ratio affects the total contact area between the membrane electrolyte assembly (MEA) and current collectors. Proper consideration of both the total free open ratio and the total contact area between the MEA and current collectors is necessary for the design of DMFC current collectors. In addition, a longer total perimeter of the free openings yields higher cell performance with the same free open ratio of the current collectors.     

CPC热管式真空管集热器的集热效率研究

介绍了CPC(compound parabolic concentrator)热管式真空管集热器的结构,对CPC热管式真空管太阳能集热器进行了传热分析,并对CPC热管式真空管集热器、热管式真空管集热器和CPC热管式集热器的集热效率进行了对比计算。CPC热管式真空管集热器的集热效率的理论计算和试验结果表明:CPC热管式真空管集热器的集热效率最佳。     

Multi-variable optimisation of PEMFC cathodes based on surrogate modelling

A two-dimensional, steady state, isothermal agglomerate model for cathode catalyst layer design is presented. The design parameters, platinum loading, platinum mass ratio, electrolyte volume fraction, thickness of catalyst layer and agglomerate radius, are optimised by a multiple surrogate model and their sensitivities are analysed by a Monte Carlo method based approach. Two optimisation strategies, maximising the current density at a fix cell voltage and during a specific range, are implemented for the optima prediction. The results show that the optimal catalyst composition depends on operating cell voltages. At high current densities, the performance is improved by reducing electrolyte volume fraction to 7.0% and increasing catalyst layer porosity to 52.9%. At low current densities, performance is improved by increasing electrolyte volume fraction to 50.0% and decreasing catalyst layer porosity to 12.0%. High platinum loading and small agglomerate radius improve current density at all cell voltages. The improvement in fuel cell performance is analysed in terms of the electrolyte coating thickness, agglomerate specific area, conductivity, overpotential, volumetric current density and oxygen mole fraction within the cathode catalyst layer. The optimisation results are also validated by the agglomerate model at different cell voltages to confirm the effectiveness of the proposed methodologies.     

Effect of anisotropic electrical resistivity of gas diffusion layers (GDLs) on current density and temperature distribution in a Polymer Electrolyte Membrane (PEM) fuel cell

A two-dimensional two-phase model is used to analyze the effects of anisotropic electrical resistivity on current density and temperature distribution in a PEM fuel cell. It is observed that a higher in-plane electrical resistivity of the gas diffusion layer (GDL) adversely affects the current density in the region adjacent to the gas channel and generates slightly higher current densities in the region adjacent to the current collector. Also, in case of GDLs with high anisotropic thermal conductivity, the maximum and minimum temperatures in a cathode catalyst layer depend on the average current density and not the local current density.     

A direct carbon fuel cell with (molten carbonate)/(doped ceria) composite electrolyte

A composite electrolyte containing a Li/Na carbonate eutectic and a doped ceria phase is employed in a direct carbon fuel cell (DCFC). A four-layer pellet cell, viz. cathode current collector (silver powder), cathode (lithiated NiO/electrolyte), electrolyte and anode current collector layers (silver powder), is fabricated by a co-pressing and sintering technique. Activated carbon powder is mixed with the composite electrolyte and is retained in the anode cavity above the anode current collector. The performance of the single cell with variation of cathode gas and temperature is examined. With a suitable CO₂/O₂ ratio of the cathode gas, an operating temperature of 700 °C, a power output of 100 mW cm⁻² at a current density of 200 mA cm⁻² is obtained. A mechanism of O²⁻ and CO₃²⁻ binary ionic conduction and the anode electrochemical process is discussed.     

Transmittance Study of a Tubular Cover Collector

Transmittance of a tubular cover collector has been calculated for a particular orientation. Tilt of the collector is optimised for the four typical days (two equinoxes and two solstices) at Delhi and Madras, a high and low latitude station respectively. Only the two nearest neighbouring tube elements are considered, in order to take into account the shadowing effect. In the present system, where the thickness of the tube and the flat glass sheets, has been taken to be the same, the transmittance of the tubular cover has been found to be comparitively less than that of a cover formed by two parallel sheets of window glass. However, because of its cylindrical geometry, very thin glass tubes can be used for all practical purposes, thereby, increasing the transmittance to a great extent. It has also been concluded that for all tubular covers including this system, hour angle instead of angle of incidence is an exact parameter to study the variation of effective transmittance. The difference in the mode of variation of transmittance with hour angle in the present system, with that in case of tubular collector, is attributed to the variation of average angle of incidence (local) with hour angle.