Advancements in radiation-induced grafted anion-exchange membranes: Controlling pre-irradiation parameters of high-density polyethylene for enhanced fuel cell performance and durability

Manufacturing anion-exchange membranes (AEMs) with high durability is a current challenge for low-temperature alkaline fuel cells. In this work, a series of AEMs based on high-density polyethylene (HDPE) is synthetized by radiation-induced grafting (RIG) method considering various pre-irradiation conditions, such as temperature and atmosphere. The AEMs are extensively characterized, including assessments of the degree of grafting (DoG), ion-exchange capacity (IEC), water absorption properties, and hydroxide conductivity. Additionally, their molecular structure and thermal and mechanical properties are evaluated. Techniques, such as atomic force microscopy (AFM) and synchrotron small angle x-ray scattering (SAXS), are employed for analysis of AEMs morphology. Finally, the AEMs are applied in an H₂-O₂ anion-exchange membrane fuel cell (AEMFC) and subjected to a short-term stability test. Among the tested AEMs, the one pre-irradiated at low temperature (−10 °C) and air atmosphere exhibits excellent AEMFC performance of 2.1 W cm⁻². This sample possesses high OH⁻ conductivity of 208 mS cm⁻¹ at 80 °C, and the stability test shows a conductivity loss of −0.06 % h⁻¹ during 100 h under reduced relative humidity (80 %). Applying an accurate protocol for controlling pre-irradiation parameters can effectively reduce the irradiation degradation effects.