Recent Advances in the Recovery of Ionomer Membranes from Used Membrane Electrode Assemblies: A Review

Abstract

The growing demand for proficient, sustainable energy storage and supply technologies has sparked the development of advanced ionomer membranes, electrodes, and metal catalysts. These membranes have critical functions in electrochemical devices, such as fuel cells, electrolyzers, and batteries, by facilitating proton transfer and providing essential reactant barriers. Perfluorosulfonic acid (PFSA) membranes are often favored for their superior proton conductivity and chemical, mechanical, and thermal stability. In proton exchange membrane fuel cells (PEMFC), they feature a sophisticated multilayer system, membrane electrode assembly (MEA) comprising the ionomer membrane, electrode, catalyst layer, and gas diffusion layer (GDL), with bipolar plates (BPs), and end plates used to connect several fuel cells in a stack. However, the lack of recycling processes for the deteriorated ionomer membrane from end-of-life (EoL) secondary sources leads to the accumulation of costly membranes that pose environmental risks and present a significant sustainability challenge due to high material costs. To address these issues, research is focused on sustainable recovery processes for ionomer membranes through dissolution using less hazardous solvents, aiming to minimize waste, maintain membrane integrity, and reduce power input. The objective of this review article is to present an overview of the recent recovery and recycling processes of ionomer membranes from EoL fuel cells and highlight some of the limitations of the membrane recycling processes as sustainable measures.