Exploration of significant influences of the operating conditions on the local O2 transport in proton exchange membrane fuel cells (PEMFCs)

• Published in: Physical chemistry chemical physics : PCCP 2017, Vol.19 (38), p.26221-26229
• Main Authors: Shen, Shuiyun, Cheng, Xiaojing, Wang, Chao, Yan, Xiaohui, Ke, Changchun, Yin, Jiewei, Zhang, Junliang
• Format: Article
• Language: English
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/c7cp04837h

A drastic reduction of the Pt loading in the cathode catalyst layers (CCLs) of proton exchange membrane fuel cells (PEMFCs) is much desired. However, a decrease in Pt loading inevitably leads to an unexpected increase of local O 2 transport resistance ( r Local ) and severely weakens the fuel cell performance, particularly at high current densities. Thus, it is both urgent and meaningful to explore the impacts of the operating conditions on r Local in CCLs and therefore to clarify the intrinsic mechanism. Herein, we systematically explore the influences of the operating conditions, in terms of the dry O 2 mole fraction, the relative humidity, the operating pressure and the temperature on r Local using limiting current measurements combined with mathematical calculations. The results show that, in contrary to the established rules, r Local in CCLs of PEMFCs is aggravated when the dry O 2 mole fraction or the operating pressure are increased. It is also experimentally found that r Local in CCLs is alleviated with the increase in the relative humidity or the operating temperature. Moreover, an adsorption controlled solution-diffusion model is proposed to illuminate the local O 2 transport behavior in CCLs of PEMFCs, and it accounts for the influence of the dry O 2 mole fraction on r Local in CCLs. Contrary to established rules, the local O 2 transport resistance is aggravated along with the increase in dry mole fraction O 2 .