抗积碳的固体氧化物燃料电池功能梯度阳极材料最优性能研究

The conventional SOFC anode material is the Ni-YSZ cermet, which offers excellent catalytic properties, mixed conductivity and good current collection. However, such cermet presents some disadvantages related to the low tolerance to carbon build up when operating under hydrocarbon fuelling.This study's focus is to improve the electrochemical performance and the tolerance to carbon deposition of the anode,finally increase the operational stability of hydrocarbon-fueled SOFC.In this study,a three-layer structure anode-supported composite membrane running on hydrocarbon is fabricated by tape casting and screen printing method.A La0.75Sr0.25Cr0.5Mn0.5O3(LSCM)-yttria-stabilized zirconia(YSZ) (LSCM-YSZ)support layer and a Ni-yttria-stabilized zirconia(YSZ)(Ni-YSZ)active layer with a Cu-La0.75Sr0.25Cr0.5Mn0.5O3-CeO2(Cu-LSCM-CeO2)catalyst layer were prepared by screen-printing Cu-LSCM-CeO2 slurry on the surface of the LSCM-YSZ support layer.The addition of the Cu-LSCM-CeO2 catalyst layer to the LSCM-YSZ support layer and the Ni-YSZ active layer can be expected to yield better performance in hydrocarbon fuel. The performances of single cell,combined with the composition of exit gas is carried out to study the kinetics of hydrocarbon oxidation reaction of the three-layer structure anode, to study the variation regularity of the performance of the cell and functioning parts of the cell as function of operating time, to analyze the reason of the degradation in the performance of the cell with this structure anode in hydrocarbon fuel, which eventually realize the functional design and fabrication of this structure anode materials in SOFC fueled by hydrocarbon fuel under theoretical guidance.

传统的固体氧化物燃料电池(Solid Oxide Fuel Cell,SOFC)直接使用碳氢化合物燃料时存在碳沉积以及Redox循环时体积变化大等问题。本项目将围绕改善SOFC阳极材料的抗碳沉积性能和电化学性能，提高阳极材料在碳氢化合物燃料中的稳定性这一科学目标开展研究。采用阳极抗积碳材料功能梯度结构设计的方法，通过流延共烧结和丝网印刷法制备Cu/LSCM-CeO2/LSCM-YSZ/Ni-YSZ/YSZ阳极支撑型复合膜，以功能梯度阳极材料协同作用的方式相互取长补短，可望解决碳氢化合物燃料发电时的碳沉积问题；通过SOFC的发电实验，结合反应气体的成分分析，综合多种表征手段研究碳氢化合物燃料在功能梯度阳极材料上发生电化学反应的动力学过程；研究电池总体性能及各部件性能随时间的变化规律，分析电池性能衰减的原因，实现理论指导下直接碳氢化合物SOFC功能梯度阳极材料的功能化设计与制备。

固体氧化物燃料电池(Solid Oxide Fuel Cell,SOFC)由于工作温度高可以实现燃料的内重整，对燃料的适应性强，除氢气外，还可直接使用甲烷等碳氢化合物。在Ni/YSZ阳极中，碳沉积主要是由于Ni对甲烷等燃料的裂解反应具有催化作用，使燃料裂解为氢气和碳，所以研究适应甲烷燃料的阳极材料一直备受关注。.本课题采用阳极抗积碳材料功能梯度结构设计的方法，将目前已知的催化性能优良的Cu/La0.75Sr0.25Cr0.5Mn0.5O3(LSCM)-CeO2、抗碳沉积性能优异的LSCM-YSZ和电化学活性优越的Ni-YSZ三种阳极材料组合起来，将对阳极的多种要求由不同功能层承担，并使各层相互配合，消除甲烷燃料在SOFC阳极上的碳沉积现象，并提高阳极在甲烷燃料中的稳定性和对电化学反应的催化活性，达到足够的功率密度。.(1) 应用丝网印刷和共烧结制备LaNi0.6Fe0.4O3-δ/Sc0.1Zr0.9O1.95/LaNi0.6Fe0.4O3-δ对称电池。实验表明，在750oC工作温度下纯LaNi0.6Fe0.4O3-δ阴极的极化电阻为0.70Ω•cm2，而21.3%(by mass)GDC包覆的LNF-GDC复合阴极的极化电阻最小(0.13Ω•cm2)。GDC的包覆加速气体/阴极/电解质三相界面反应区的扩散过程，降低阴极极化电阻，其活化能最小(136.80 kJ•mol-1), 故其阴极性能最佳。.(2) 采用流延法制备LSCM-YSZ阳极支撑层/Ni-ScSZ阳极活性层/ScSZ电解质层复合膜，在LSCM-YSZ支撑层上印刷一层Cu-LSCM-CeO2催化层，制备功能梯度阳极，以21.3%(by mass)GDC包覆的LNF作阴极，制备单电池。研究表明Cu/LSCM/CeO2比为2.15:7.0:0.85(by mass, Cu/CeO2比为2.5:1)功能梯度阳极(LSCM-YSZ2510)具有较好的性能，单电池在750℃、800℃时以甲烷为燃料的最大功率密度分别为491和670mW cm-2。该单电池在750°C于甲烷中运行240h，性能稳定，碳沉积极少。.本项目研究的功能梯度结构阳极材料能够在不添加外部重整设备的情况下使用来源广泛、廉价的甲烷燃料，能够显著降低SOFC的运营成本，提高SOFC的实用性，对推动SOFC的技术进步和商业化进展都有重要意义。