Influence of pore size optimization in catalyst layer on the mechanism of oxygen transport resistance in PEMFCs

作     者：Shumeng Guan Fen Zhou Jinting Tan Mu Pan 

作者机构：State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Hubei Provincial Key Laboratory of Fuel Cells Wuhan University of Technology 

出 版 物：《Progress in Natural Science:Materials International》 (自然科学进展·国际材料(英文))

年 卷 期：2020年第30卷第6期

页      面：839-845页

核心收录：

学科分类：0808[工学-电气工程] 081705[工学-工业催化] 08[工学] 0817[工学-化学工程与技术] 

基　　金：financially supported by the National Key Research and Development Program of China (Program No. 2016YFB0101200 (2016YFB0101205)) National Natural Science Foundation of China (Program No. 21875177) Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory” (Program No. XHD2020-002-03 and XHD2020-002-04) 

主　　题：Pore size optimization Pore-forming agent Oxygen transport resistance PEMFC 

摘      要：In PEMFC, the oxygen transport resistance severely hinders the cell from achieving high performance. In this paper, pore-forming agent was used to optimize the pore size distribution of the catalyst layer(CL), and to study its effect on the mechanism of oxygen transport resistance, including molecular diffusion resistance, Knudsen diffusion resistance, and local O2resistance in CL. The results showed that with the pore formation the cell performance had a significant improvement at high current density, mainly due to its better oxygen transport properties, especially under low platinum conditions. The addition of pore-forming agent moved the pore diameter toward a larger pore diameter with a range from 70 to 100 nm, and also obtaining a higher cumulative pore volume. It was found that the increase of the cumulative pore volume and larger pore size were conducive to the diffusion of oxygen molecules in CL, and the resistance caused by which was the dominant part in total transport resistance. Further tests indicated that the improvement of molecular diffusion resistance was much larger than that of Knudsen diffusion resistance in the catalyst layer after pore formed. In addition, the optimized pore structure will also get a higher number of effective pores, which resulted in an increased effective area of the ionomer on the Pt surface. The higher effective area of the ionomer was particularly beneficial for the reduction of local O2resistance with low Pt loading.