Mesoscopic modeling of transport resistances in a polymer-electrolyte fuel-cell catalyst layer: Analysis of hydrogen limiting currents. (1st December 2019)

• Record Type: Journal Article
• Authors: Mu, Yu-Tong; Weber, Adam Z.; Gu, Zhao-Lin; Tao, Wen-Quan
• Is Part Of: Applied energy. Volume 255(2019)
• Publication Date: 2019-12-01
• Subjects: PEFC -- Local transport resistance -- Low-loaded platinum -- Catalyst layer -- Lattice Boltzmann method; Power (Mechanics) -- Periodicals; Energy conservation -- Periodicals; Energy conversion -- Periodicals; 621.042
• DOI: 10.1016/j.apenergy.2019.113895
• Languages: English
• ISSNs: 0306-2619

Abstract

Highlights: Local transport resistances of catalyst layer in PEFCs are numerically predicted. A 3D multiscale model considering interfacial transport resistances is proposed. Bulk resistance of ionomer thin-film dominates the local transport resistance. Higher Pt/C ratio and bare carbon fraction lead to higher local transport resistance. Contribution of pores to catalyst layer resistance is small at low Pt loadings. Abstract: Understanding transport resistances in a polymer-electrolyte fuel cell (PEFC) catalyst layer (CL) is essential to mitigate the unexpected voltage loss when using low loadings of precious metals. In this paper, we explore through mesoscopic modeling the quantification analyses of the transport resistances in CL as derived using hydrogen-pump limiting current. Numerical treatments on the conjugated interfacial conditions at interfaces of ionomer/pore and Pt/ionomer are proposed to describe the mesoscopic transport processes of hydrogen and proton. Characterizations of the reconstructed microstructure of CL are performed. Parameter analyses on the influences of the critical transport properties such as the permeation coefficient and the dissolution and adsorption reaction rates at the surfaces of ionomer/pore and Pt/ionomer on the local transport resistance are presented. It is found that the local transport resistance is mainly originated from the diffusion resistance of the ionomer thin-film, which is more resistive than its bulk analogue with its permeation coefficient fitted to be 5.9% of the bulk one. The interfacial transport resistances and the diffusion resistance are coupled. The local transport resistance increases with I/C ratio due to thicker ionomer coated on the particles. Higher Pt/C ratio and bare carbon fraction lead to higher local transport resistance since the ionomer loading relative to Pt roughness factor decreases. The local transport resistance decreases with the porosity. The contribution of pores to the CL resistance, which decreases with the porosity, is comparatively small at low loadings.