Quarternized polysulfone/ZSM‐5 zeolite composite anion exchange membrane separators for aluminum‐air battery

Abstract A membrane is a critical component of an Al‐air battery because it provides ion transport and ensures separation of the anode and cathode. In this work, a series of quaternized polysulfone (QPSF) membrane blended with ZSM‐5 zeolite anion exchange membranes (AEMs) were fabricated by solution casting to be used as separators in Al‐air batteries. All membranes showed moderate to excellent water uptake (WU), swelling ratio, ion exchange capacity (IEC), and ion conductivity measurements (IC). Incorporation of ZSM‐5 zeolite resulted in hydrophilicity and improved WU, with QPSF/3 wt% ZSM‐5 retaining 114% water at room temperature. The QPSF/3 wt% ZSM‐5 composite membrane was the best performing membrane with the IEC and the highest hydration number of 2.85 mmol g −1 , 2.23, and a maximum of IC of 229.85 mS cm −1 at room temperature, respectively. QPSF/3 wt% ZSM‐5 retained 65% of its original IC in an alkaline medium after 7 days. QPSF/3 wt% ZSM‐5 exhibited a stable discharge voltage of 1.3 V and a specific capacity of 11,716 mAh/g Al in a laboratory fabricated Al‐air cell. This study provides an excellent anion exchange composite membrane separator candidate for Al‐air battery applications.