管式固体氧化物燃料电池模型研究进展

管式结构是固体氧化物燃料电池一种重要结构类型,在设计和密封方面具有优势。近年来建模成为管式固体氧化物燃料电池研究的一种重要手段,已经发展出各种各样的模型。介绍了电化学模型、综合模型(同时耦合电化学、流动及传热)以及动态模型,比较各类模型优点和不足,指出有必要建立能同时从宏观和微观多层面多角度评价电池的全面模型。     

固体氧化物燃料电池发展及展望

在21世纪的今天,能源和环境对人类的压力越来越大.当人们把能源供应仍然寄托于煤的综合利用为主时,可以直接使用多种碳基燃料的高温固体氧化物燃料电池(SOFC)发电技术将是新型高效洁净能源的有效途径之一.在发展大型电站技术的同时,固体氧化物燃料电池作为分布式电站和备用电源技术及示范工程蓬勃开展.世界范围内,各种相关鼓励SOFC快速发展的政策陆续出台.千瓦量级的SOFC发电系统将在军方首先试用,多国联合的SOFC商业化进程正在加速实施.     

固体氧化物燃料电池电压检测系统设计与应用研究

固体氧化物燃料电池堆由多片单电池串／并联组成,各单电池的电压是表征电池堆性能的关键参数。大功率电池堆高达数百伏的累积电势,成了单电池电压测试的障碍。本文设计了一种高共模抑制比的差分运算电路,该电路在测试中能有效地抑制燃料电池堆的共模电压。实验优化了利用该电路进行燃料电池电压检测的最佳方案。     

Development and characterization of vacuum plasma sprayed thin film solid oxide fuel cells

The vacuum plasma spraying (VPS) process allows the production of thin solid oxide fuel cells (SOFCs) with low internal resistances. This enables the reduction of the cell operating temperature without a significant decrease in power density. Consequently, the long-term stability of the cells can be improved and low-cost materials can be used. Different material combinations and spray parameter variations were applied to develop thin-film SOFCs, which were plasma sprayed in a consecutive deposition process onto different porous metallic substrates. The use of Laval nozzles, which were developed at the German Aerospace Center (DLR), and the use of conical F4V standard nozzles enable the fabrication of thin gas tight yttria- and scandia-stabilized ZrO₂ (YSZ and ScSZ) electrolyte layers and of porous electrode layers with high material deposition rates. The optimization of the VPS parameters has been supported by laser doppler anemometry (LDA) investigations. The development of the plasma-sprayed cells with a total thickness of approximately 100 μm requires an overall electrical and electrochemical characterization process of the single layers and of the completely plasma-sprayed cell assembly. The plasma-sprayed cell layers reveal high electrical conductivities. The plasma-sprayed cells show very good electrochemical performance and low internal resistances. Power densities of 300 to 400 mW/cm² at low operating temperatures of 750 to 800 °C were achieved. These cells can be assembled to high performance SOFC stacks with active cell areas up to 400 cm², which can be operated at reduced temperatures and good long-term stability.     

SOFC单电池局部性能的评价与测试

为了制备高性能大面积固体氧化物燃料电池(SOFC)单电池,解决由于面积过大而导致的单电池上气体分配不均匀及各部分温度差异,通过实验设计测试了单电池的各个区域的性能,包括局部电性能和局部温度.实验在1片10cm×10cm(有效反应面积9cm×9cm)的阳极支撑SOFC单电池上进行,电池的阴极以及空气气体分配板和集流器都被...     

Creep behaviour of porous SOFC electrodes: Measurement and application to Ni-8YSZ cermets

A methodology is proposed in this study to investigate the creep properties of porous Ni-8YSZ cermet. Creep experiments have been conducted under reducing atmosphere at the typical SOFC operating temperatures. Specimens have been loaded in a four-point bending test bench. A special attention has been paid in this work to the analytical and numerical modelling of the mechanical test. It has been highlighted that Ni-8YSZ exhibits substantial creep strain rates even at relative low temperatures (700 °C < T < 850 °C). The creep exponent has been found to be just slightly higher than unity (1 < n < 2) while the activation energy has been determined equal to Q = 115 kJ mol⁻¹.High-temperature plastic strains of both Ni and 8YSZ phases have been estimated through the local stress acting on the cermet particles. This analysis indicates that creep behaviour of the Ni-8YSZ composite is not influenced by the metallic phase, but is controlled by the deformation of the 8YSZ matrix. It is also proposed that cermet creep mechanism involves Zr⁴⁺cations diffusion at the surface rather than in the bulk of the 8YSZ material.Impact of the Ni-8YSZ cermet creep on the internal stresses distribution in SOFC is discussed considering the anode supported cell (ASC) design. It is shown that cermet creep strain can induce a substantial stress decrease in the thin electrolyte.     

SOFC复合阳极中的Cu在CeO2表面上沉积的密度泛函研究

对固体氧化物燃料电池中的Cu-CeO2/YSZ复合阳极中的Cu在CeO2表面上沉积进行了密度泛函研究。Cu在CeO2的高对称性(101 0)表面的生长,首先键合于表面悬挂键或者表面成键轨道上,经过一次重排,表面的Cu层逐渐开始紊乱,变得凹凸不平并最终生长为三维团簇。对于(112 0)面,Cu初始只能键合于CeO2表面的悬挂键,然后生长为不规则的之字形结构、二维条带、二维岛并最终生长为扁平的团簇。Cu与CeO2之间存在很强的作用,在同一个吸附量下,有时可能存在多种构型,其活化能一般很低,沉积的Cu可在这些构型间来回迁移。很多位于CeO2 101 0))和(112 0)表面的Cu都带有略微的正价态,为可能的活性相,这些带正电荷的Cu有助于对燃料气的络合活化。     

Enhanced electrochemical properties of Bi-layer La0.5Sr0.5CoO3−δ cathode prepared by a hybrid method

Bi-layer La_0.5Sr_0.5CoO_3−δ (LSCO) cathodes are processed by a hybrid method that combines a seed layer prepared by a pulsed laser deposition (PLD) technique and a conventional cathode layer (∼7 μm in thickness) by a screen printing method. By inserting the PLD seed layer with the thickness of ∼500 nm or less, robust cathode films with desired microstructure and excellent adhesion properties with the underlying electrolyte layer, are successfully fabricated. The area specific resistance (ASR) of the hybrid cathode layers decreases about 5 times compared with that of the single layer cathode films prepared by the conventional screen printing method. The hybrid approach provides a cost-effective way to fabricate thick cathode films with significantly enhanced electrochemical properties for solid oxide fuel cells (SOFCs).     

Placement of reference electrode in solid electrolyte cells

The placement of reference electrodes in solid state ionic conductors is not as flexible as in liquid state electrochemistry. This is in particular a problem when material from the gas phase is involved, as in solid oxide fuel cell. Many of the arrangements used are problematic: either they produce results that are very sensitive to electrode placement, change the potential distribution, do not provide a uniform current density and overpotential at the electrode or require delicate patterns liable to fail. We here present a new approach suitable for thin layer SOFC. It includes a calibration procedure derived from numerical simulations in combination with experiments. This allows the use of the common three-electrode arrangement on thin solid electrolyte (SEs) where the reference electrode is placed side by side with the working electrode, on an extension of the thin layer SE. This is so despite the sensitivity of that arrangement to both misalignment of the electrodes and to a difference in the impedance of the two current carrying electrodes. The misalignment tolerated, with the present method, may exceed the SE thickness. The allowed misalignment increases with the electrode/SE impedance ratio. The method copes also with the difference in the electrode impedance. Two special configurations are discussed in which the calibration is not required. However, these require a more accurate preparation technique of the cell.     

Fabrication of wormhole-like YSZ and Ni-YSZ by the novel soft-hard template CTAB/NaCl-assisted route. Suppressing Ni coalescence in SOFC

A novel one-pot synthesis route leading to the formation of a wormhole-like structure was developed for the successful fabrication of porous YSZ and Ni-YSZ systems. This method involved co-precipitation in the presence of the micelle-forming agents CTAB/Pluronic P123 and crystallising NaCl. The obtained skeletons were mechanically stable and presented almost 50% uniform, open porosity without using any additional pore-formers. The fabricated 0.3 M CTAB/NaCl Ni-YSZ showed better long-term electrical stability in hydrogen than a traditional Ni-YSZ cermet. It resulted from the suppression of Ni structural changes throughout the anode scaffold. Moreover, higher electrochemical activity of this novel anode is expected due to the smaller particle sizes of Ni/YSZ, high homogeneity, highly developed TPB, and better interfacial interaction between the Ni and YSZ. Therefore, the novel soft-hard templating method is recognised as a promising route for the fabrication of the YSZ or Ni-YSZ with a highly developed microstructure and improved stability.