The Challenges to Ultra-Low-Platinum PEMFC Cathode and the Electrocatalyst Design Thereof

Abstract

Polymer electrolyte membrane fuel cell (PEMFC) has been extensively studied because of its many desirable qualities for the automotive application, including high power density, low operating temperature (~80 oC) as well as quick start-up and match-up to the power demand. Although appealing, a challenge caused by the high Pt loading in the cathode should be addressed before the mass production of fuel cell vehicles. In this regard, the research topic is now urgently focused on to use ultra-low Pt loading (≦0.1 gPt/kW) in the cathode of PEMFCs. It is noted that both the electrode kinetics of oxygen reduction reaction (ORR) [1] and mass transport for conventional cathodes with low Pt loading do not apply to the cathodes with ultra-low Pt loading, especially for the local mass transport surrounding Pt particles in the catalyst layer [2]. Herein, the challenges in the ultra-low Pt cathode in terms of ORR kinetics and local transport resistance will be clarified and the corresponding solution in terms of the electrocatalyst design will be provided. How the ORR kinetics on the cathode changes with the Pt loading decreasing will be examined in detail and the difference in the transport resistance in each component (Figure 1), especially the O2local transport between the ultra-low Pt cathode and high Pt cathode will be elucidated. The effects of catalyst type, specific activity, Pt loading as well as the cathode structure on the cell performance will be discussed, thus providing a solid scientific guideline for developing cathodes with ultra-low Pt loading and accelerating the commercialization of PEMFCs using cathodes with ultra-low Pt loading. Acknowledgements This work was supported in part by National Natural Science Foundation of China (Grant No. 21373135 and 21533005) and Science Foundation of Ministry of Education of China ( Grant No. 413064).