Symbio FCell (France)

Understanding the relationship between flooding behavior of Proton Exchange Membrane Fuel Cell Catalyst Layers (CLs) and their manufacturing parameters is of crucial importance to achieve global cell performance goals. We report here a novel computational workflow able to predict how manufacturing parameters impact the CL microstructure and its associated transport properties. The workflow comprises one discrete element method model for 3D CL microstructure generation that uses four manufacturing parameters inputs. The microstructures are then characterized with a novel two phase-field lattice Boltzmann model. A two-contact angle description was chosen to unravel the wetting behavior difference between the ionomer and carbon with platinum. The physics were verified using standard tests. The modeling workflow was tested on five microstructures generated with different water to isopropanol volumetric ratio in the solvent composition used to prepare the CL inks. Liquid water coverage ratio on the solid phases, relative permeabilities, and capillary pressures were calculated for each case and compared. The coverage ratio is noticeably influenced by the solvent composition, while the two-phase invasion is mostly impacted by the contact angle of the materials. Additionally, regular correlations used in macroscopic models were compared with the obtained results. We believe that our approach allows gaining unprecedented insights on the transport processes happening in CLs and can be also implemented in a macro-scale model for performance estimation.

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).

An optimized potential window for efficient platinum electrodissolution, the first step of a Pt recycling process, is proposed.

The FCEVs have earned more attention in the past years, with the urge of finding green alternatives for fuel cells. Very convincing small series vehicles (such as the new Mirai) are spearheads for PEMFC technologies and shows how complex both the system and the MEAs have to be designed. More specifically, in the case of the MEA, the importance of mesoporous carbons as carbon support [1], enabling lower Pt poisoning, but also lower O2 resistance in the catalytic layer [2] has been clearly emphasized. In addition, the porosity distribution of the material was concluded to be both favourable to O2 transport, but also to ionomer film continuity onto the carbon support [2]. However, recent literature also indicated with DFT technologies that the solvent system used (hence the ink formulation) could have a major impact on the performance [3], with possible ionomer penetration in the pore, making sluggish performance with an important bottleneck to oxygen transport.In this study, we aim at demonstrating how solvents modify the interaction between the ionomer and the mesoporous carbon, with a systematic performance screening in PEMFC configuration (25 cm²), while changing ink formulation or parameters, linking the change of the pore distribution of the coated electrode (N2 adsorption), with the performances.[1] T. Yoshizumi, H. Kubo, M. Okumura, and T. Motor, SAE inernational, 1–6 (2021).[2] N. Ramaswamy, W. Gu, J. M. Ziegelbauer, and S. Kumaraguru, J. Electrochem. Soc., 167, 064515 (2020).[3] N. Kikkawa and R. Jinnouchi, J. Phys. Chem. C, 126, 11518–11528 (2022).

This paper is on the subject of identification of essential sensors for Proton Exchange Membrane Fuel Cell (PEMFC) system in Fuel Cell Electric Vehicle (FCEV) application. Sensors are classified as physical sensors and gas sensors. Physical sensors are used to detect pressure, temperature, mass flow rate and relative humidity of the fuel cell. Gas sensors consist of the hydrogen leakage detector and the environment sensor system. The environment sensor system detects gas contaminations, e.g., carbon dioxide in the air. Depending on the sensor development review and the sensor specifications comparisons, sensors owned low cost, small volume, fast response, high resolution, excellent stability and durability are suitable for FCEV application. Some future work on fuel cell sensor-set size optimization is also suggested to facilitate the move towards commercialization.