Effect of hydrophobic additive on oxygen transport in catalyst layer of proton exchange membrane fuel cells

• Published in: Journal of power sources 2018-03, Vol.379, p.338-343
• Main Authors: Wang, Shunzhong, Li, Xiaohui, Wan, Zhaohui, Chen, Yanan, Tan, Jinting, Pan, Mu
• Format: Article
• Language: English
• Subjects: CL with hydrophobic agent; Oxygen transport resistance; PEMFC; PTFE powder
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2018.01.068

Oxygen transport resistance (OTR) is a critical factor influencing the performance of proton exchange membrane fuel cells (PEMFCs). In this paper, an effective method to reduce the OTR of catalyst layers (CLs) by introducing a hydrophobic additive into traditional CLs is proposed. A low-molecular-weight polytetrafluoroethylene (PTFE) is selected for its feasibility to prepare an emulsion, which is mixed with a traditional catalyst ink to successfully fabricate the CL with PTFE of 10 wt%. The PTFE film exists in the mesopores between the carbon particles. The limiting current of the hydrophobic CL was almost 4000 mA/cm2, which is 500 mA/cm2 higher than that of the traditional CL. PTFE reduces the OTR of the CL in the dry region by as much as 24 s/m compared to the traditional CL and expands the dry region from 2000 mA/cm2 in the traditional CL to 2500 mA/cm2. Furthermore, the CL with the hydrophobic agent can improve the oxygen transport in the wet region (>2000 mA/cm2) more effectively than that in the dry region. All these results indicate that the CL with the hydrophobic agent shows a superior performance in terms of optimizing water management and effectively reduces the OTR in PEMFCs. [Display omitted] •CL with PTFE is fabricated successfully by using a low-molecular-weight PTFE.•The limiting current for CL with PTFE is much higher than that for traditional CL.•PTFE obviously reduces OTR in the dry region compared to the traditional CL.•The dry region range for CL with PTFE is broader than that of the traditional CL.•PTFE obviously improves the oxygen transport through the CL in the wet region.