Résumé
The durability of ionomer membranes is an important factor affecting the lifetime of proton exchange membrane fuel cells. Degradation of ionomer membrane causes performance losses that accelerate with time and result in catastrophic MEA failure. Membrane instability has two main origins mechanical fatigue and chemical degradation. Both modes strongly depend on the operating conditions applied: temperature, relative humidity, humidity cycling, reactant pressure, applied voltage and properties of the membrane, mainly the ionomer type and equivalent weight (EW), and membrane thickness. Thin membranes (<<20 µm) with low equivalent weight (<<800 EW) are required to achieve industry targets for FCEV however they are also more prone to undergo accelerated degradation.
This work focuses on the development and evaluation of different methods to increase durability through the development of a highly heterogeneous membrane system comprising a reinforcing component, radical scavenger and/or hydrogen peroxide decomposition catalyst and in which the architecture of the membrane is designed at the nano- to micro-metric length scales, the latter facilitated by the use of solution casting processes. Electrospun nanofibres provide mechanical strength, ensure low membrane swelling when exposed to humidity cycles, and also provide an appropriate distribution medium for radical scavenging species. This presentation will discuss benefits and remaining challenges associated with efficiency and stability of mechanical and chemical reinforcements.
Acknowledgement: This project has received funding from the Fuel Cells and Hydrogen 2 Joint Undertaking under grant agreement No 671465 VOLUMETRIQ. This Joint Undertaking receives support from the European Union’s Horizon 2020 research and innovation programme.