积碳过程对固体氧化物燃料电池阳极性能影响机理的孔隙尺度研究

The durability of solid oxide fuel cell (SOFC) fed by hydrocarbon fuels is significantly affected by the carbon deposition in anode, which is an emerging technology barrier to the commercialization of SOFC. Therefore, the mechanisms of carbon deposition and its effect on anode performance need to be understood thoroughly. Under certain conditions, hydrocarbon fuel is catalyzed to crack after diffusing to the catalyst, and hence carbon deposition occurs. The deposited carbon deactivates the catalyst and changes the pore microstructure, which greatly affects the transport and reactions in anode and deteriorates the anode performance. In the study of this proposal, mechanisms for influences of carbon deposition on anode performance are revealed by studying the transport and reactions in porous anode. Based on Lattice Boltzmann method and imaging technology for the 3D microstructure of porous electrode, a pore scale simulation method considering the heterogeneity and nano/micro scale effect of the anode microstructure is established for the transport and reactions in porous anode. Using this model, the coupling mechanism of transport and reactions in anode is investigated to reveal the mechanism of carbon deposition. Based on the pore scale simulation method, an unsteady model is further developed by considering the changes of catalytically active sites and pore structure caused by carbon deposition. Using this unsteady model, the influence mechanisms of carbon deposition on anode performance is revealed by studying the coupling of carbon deposition with transport and reactions in porous anode. The study in this proposal will provide fundamental theories to develop cutting edge technologies for improving SOFC durability by suppressing carbon deposition.

固体氧化物燃料电池使用碳氢燃料引起的阳极积碳问题会显著影响电池耐久性，并严重阻碍其商业化进程，为此需要深入理解积碳产生的原因及其对阳极性能影响的机理。燃料气体传输至阳极催化剂表面，在一定条件下裂解产生积碳，从而降低催化剂活性并改变孔隙结构，显著影响多孔阳极内的物质传输与反应过程，降低阳极性能。本项目拟通过研究多孔阳极内的物质传输与反应过程，揭示积碳过程对阳极性能的影响机理。结合格子玻尔兹曼方法与多孔电极三维微结构成像技术，发展孔隙尺度下多孔阳极内物质传输与反应过程的模拟方法，综合考虑阳极微结构的各向异性和微纳米尺度特征，揭示多孔阳极内物质传输与反应过程的耦合机制，阐明积碳产生机理；进一步考虑积碳改变多孔阳极内催化活性位和孔隙结构的动态过程，发展非稳态模型，阐明积碳过程与物质传输和反应过程的耦合机制，揭示积碳过程对阳极性能的影响机理，为发展通过抑制积碳提高电池耐久性的创新技术提供理论支撑。

如何在保证固体氧化物燃料电池（SOFC）电化学性能的前提下提高其阳极抗积碳能力已成为SOFC商业化的瓶颈问题，为此需要深入理解积碳产生的原因以及积碳过程对阳极性能的影响机理。项目紧密围绕任务书设定的研究目标，对SOFC多孔阳极内的积碳过程开展了孔隙尺度的研究。发展了孔隙尺度下多孔阳极微结构内气体、载流子传输与电化学和重整反应耦合过程的格子玻尔兹曼（LB）模拟方法，该方法综合考虑了阳极微结构微纳米尺度和各向异性特征；实验制备了SOFC阳极，并采用X射线断层扫描技术重构了其三维微结构作为孔隙尺度研究的几何结构基础；实验测量了阳极极化特性曲线作为验证孔隙尺度模型的对比数据；采用经过验证的孔隙尺度LB模型研究了多孔阳极内物质传输与反应过程之间的耦合和竞争机理，揭示了阳极内积碳产生的过程及机制。项目研究结果可为同时提高SOFC电化学性能与抗积碳能力的技术创新提供理论支撑，也可为遍及能源、环境、生物等诸多领域的微纳米多孔介质内物质传输现象的分析提供研究思路和有效方法。