Investigation of Membrane–Electrode Separation Processes for the Recycling of Ionomer Membranes in End-of-Life PEM Fuel Cells

With the increasing development of proton exchange membrane fuel cell (PEMFC) technology in recent years, the recyclability of the membrane–electrode assemblies (MEAs), and more specifically of the aged samples, has become an important issue to be addressed. This study reports on different routes for the separation of membrane and electrodes from end-of-life (EoL) MEAs, which represents the initial step in the membrane recycling process. A specific methodology, using ultraviolet–visible (UV–vis) spectroscopy and optical microscopy, is first developed to monitor the process of membrane–electrode separation in the case of EoL MEAs. The quality of the separation of the different components is then monitored by establishing a material balance based on thermogravimetric analysis. A two-step process, based on the use of diluted isopropyl alcohol (IPA) solutions with stirring, is proposed as an efficient and environmentally friendly method for the effective separation of the electrodes from the ionomer membrane. This process offers a high yield recovery (up to 95% for PFSA), low energy consumption, and the avoidance of emission of harmful gases. First, the physical separation of membrane and electrodes is achieved under a mild temperature (40 °C), thus enabling the recovery of carbon, Pt, and ionomer binder on one side and the perfluorosulfonic acid (PFSA) ionomer membrane on the other side. Second, the further dissolution of the PFSA ionomer membrane at a higher temperature (75 °C) allows the recovery of a PFSA ionomer dispersion. Finally, the most promising processes are tested on both pristine and different aged MEAs to demonstrate the robustness of the methodology, regardless of the ionomer membrane type. The resulting hydroalcoholic ionomer solutions from EoL MEAs could then be reused in diverse applications such as purification technologies (pervaporation, ultrafiltration).