Antioxidant Poly(aryl piperidinium) Anion Exchange Membrane for Fuel Cells

Anion exchange membranes (AEMs) serve as critical components in anion exchange membrane fuel cells (AEMFCs), requiring exceptional chemical stability under harsh operating conditions. Although their alkaline stability has been thoroughly studied, antioxidant stability has received limited attention due to unclear oxidative degradation mechanisms. This work identifies backbone oxidative cleavage and phenyl oxidation as the primary degradation pathways in poly(aryl piperidinium) AEMs. We demonstrate that incorporating radical scavengers effectively enhances the membrane antioxidant properties. Specifically, hydroquinone (HQ)-functionalized AEMs through ionic cross-linking show a remarkable 130% improvement in antioxidant performance (168 h) compared to pristine AEMs (72 h). It exhibits improved mechanical stability, maintaining 70.0% (20.3 MPa) and 62.8% (18.2 MPa) strength retention after extended 5000 h alkaline stability and fuel cell lifespan tests, respectively, approximately twice the durability of pristine AEMs. This work provides fundamental insights into AEMs oxidative degradation and offers a practical approach to extend the durability of AEMFCs durability.