Reversal Tolerant Anodes Using Protective Layers for Highly Robust Automotive Fuel Cells

Fuel cell electric vehicles (FCEVs) powered by polymer electrolyte membrane fuel cells (PEMFCs) need an improvement in their durability and robustness to achieve broader commercialization. Cell reversal induced by hydrogen starvation could significantly reduce the performance and durability of the PEMFC system in a short time. Here, we present the cell performance degradation and cell failure mechanisms during hydrogen starvation through examining membrane electrode assemblies (MEAs) with several different anode structures. For an MEA with conventional anode composed of carbon-supported platinum catalyst (Pt/C), the degradation caused by cell reversal primarily comes from carbon support corrosion. It is worth noting that an MEA with Pt black-only anode without any carbon also fails during hydrogen starvation. It is postulated that cell failure and performance degradation of the MEA with Pt black-only anode are caused by the corrosion of carbon materials present in the anode microporous layer (MPL) in gas diffusion layers. Based on these findings, we proposed a reversal tolerant anode (RTA) composed of both Pt black as a catalyst layer and thin titanium (Ti) as a protective layer. The conventional MEA with Pt/C anode exhibits the highest cell voltage degradation rate of 15.2% loss/min and the lowest reversal tolerance, whereas this new RTA MEA with Pt black and 13.0 μm thick Ti layer anode gives the lowest cell voltage degradation rate of 0.049% loss/min and the highest reversal tolerance, which is an approximately 310-fold increase compared with the conventional MEA with Pt/C anode. These findings will greatly contribute to designing a new concept of RTAs and enhancing the cell voltage reversal tolerance of PEMFCs dramatically under severe operating conditions of hydrogen starvation and thus improving the competitiveness of FCEVs.