Recycling Nafion in ionic liquids: a sustainable route for fuel cells

In light of current climate challenges, the decarbonization of energy systems has become a major priority. In this context, fuel cells represent a promising electrochemical technology, particularly for mobility and electricity generation with low local emissions. Their deployment relies on proton exchange membranes, such as Nafion. However, despite its excellent electrochemical performance, Nafion remains costly to produce. Moreover, the use of fluorinated polymers raises environmental and health concerns, and no industrial recycling process currently exists, representing a major challenge for the sustainable development of fuel cell technologies.

This study explores an innovative strategy based on ionic liquids—non-volatile liquid salts composed entirely of ions, whose properties can be tailored for specific applications—to enable membrane dispersion and subsequent recovery (Figure). To understand how Nafion disperses, a multiscale approach was employed, combining macroscopic swelling kinetics, small-angle neutron scattering (SANS – ILL, D16), and wide-angle X-ray scattering (WAXS). These complementary techniques probe different length scales: WAXS provides information on structural changes at the molecular level, while SANS gives access to the nanoscale organization of ionic domains and the polymer matrix. Building on this approach, neutron contrast variation using partially deuterated ionic liquids will provide additional insight by enabling a more detailed separation of structural contributions.

Overall, this work opens new perspectives for the sustainable recycling of fuel cell membranes, for guiding the selection of ionic liquids, and for extending the process to end-of-life membrane-electrode-assemblies, potentially in combination with catalyst recovery [1,2].

[1] M. Coudray et al., Industrial & Engineering Chemistry Research, Part 1, Vol 62, 2023 
[2] M. Coudray et al., Industrial & Engineering Chemistry Research, Part 2, Vol 62, 2023