The recycling technologies optimisation for end-of-life PEM fuel cells is one of the main activities advanced within BEST4Hy. As important European research centre in the Energy field, the CEA gives its contribution with the exploration of novel technologies for the dismantling and recovery of Platinum and Ionomer from the PEMFC. Together with Hensel Recycling and EKPO, the CEA is one of the main actors of this activity.

Here, a short interview to better understand the results obtained until now with the experiments performed by the CEA. Marion Chevallier, R&D Researcher and Engineer, answers to our questions:

How to recover critical raw materials from a PEMFC?

There are two main steps to recover the critical raw materials from a PEM fuel cells: the first is the dismantling of the MEA, which is the core of each cell; the second one is the specific recovery of precious materials, such as Platinum. Within Best4Hy project, I deal with the recovery of Platinum from the MEA’s fuel cells. As CEA, we have developed a new process based on an electroleaching and electrodeposition treatment. Our technique consists in freeing the platinum from the catalytic membrane (which is stick with other components) and depositing it immediately on another convenient support, which is a recycled GDL. This is done electrochemically: electrons are removed from the anode to help the platinum “peel” off and are added to the other side, at the cathode, to deposit the platinum on the over-cycled material.

The electrolyte used for this electron’s movement is composed of a composite ionic liquid that provides the properties required for the process. The ionic liquids are non-toxic and non-hazardous solvent, which makes our process safe and green, as its free from organic solvents or acidic and oxidising solutions.

How this process bring innovation?

For the electroleaching and electrodeposition process, the main innovation is the one single step execution: a single electrolyte bath allows for both electrochemical leaching and deposition. In simple word, material extraction and deposition take place immediately, avoiding the several steps usually required in the conventional metal recovery treatments. The use of ionic liquids for this recycling step is also an innovative aspect, meeting safety and environmental criteria. The concept of one-step recovery process for Platinum in ionic liquids was patented in 2017, but thanks to BEST4Hy we are now working on a new aspect, adapting it on new types of MEAs and real-life materials.

Which kind of barriers did you find in this processs and which solutions have you proposed?

Two main challenges were found during the recovery process. A major obstacle was to find anodes that allow the oxidation of Platinum at high potentials, while ensuring the integrity of the anode material and the absence of oxidation. For this purpose, we used metal mixed oxides grids that resist to high potentials. In addition, we were able to electrolyse the Platinum on both sides of the CCM, saving time and energy in the process. Our second challenge was to adapt the process, and thus the patent, to the current most popular electrode in the PEM: in the past years GDE (Gas Diffusion Electrode) was very common, but now CCM (Catalyst Coated Membrane) is the most used materials. The CCM do not have conductive properties, compromising the success of the electroleaching and electrodeposition processes. Finally, we found out mesh metal mixed oxides as best solution for both of the mentioned challenges and the desired Platinum recovery targets.

Does this process have the potentiality to be scaled-up?

We have just started the scaling-up phase for the electro-leaching and electro-deposition technology. Next months will be focused on this objective, testing the current 3 millilitres of samples, used in laboratory, to scale up to 10 litres target. We are already working on a 5-litre scale pilot, which should be operational within a few months. Potentiality to handle several stacks at once also exists, but at the present time it is not part the project’s mission.

The scale-up phase really needs a huge amount of material to test, so I would mention the importance of EKPO, as fuel cells supplier and BEST4Hy’s partner. EKPO provided us over 200 CCMs to test. It is very important the age of the CCMs received, which range from fresh (0h of use), old (200h of use) to very old (2800 h of use) ones. This age variety of CCMs enables us to check the robustness of the process on different aged materials.

Something really remarkable, it is also the attention captured from our BEST4Hy stakeholder’s network: two companies already asked about our novel processes developed in the framework of the project. This means a rising interest from the industries and the energy sector for a more sustainable pathway of hydrogen technologies.

Related news and materials:

BEST4Hy at the 4th Mediterranean Symposium Electrochemistry for Environment and Energy

The CEA with BEST4Hy on The Hydrogen Standard magazine