Poly (Ether Ether Ketone) Based Anion Exchange Membrane for Solid Alkaline Fuel Cell: A Review

Solid alkaline fuel cell is employed by polymer anion exchange membrane (AEM) that is permeable to hydroxide ion. A number of polymers have been proposed for AEM which include polysulfone (PSF), poly (phenylene oxide) (PPO), and poly (ether ether ketone) (PEEK). The purpose of this paper was to conduct a critical review on the development of PEEK polymer as AEM, particularly in terms of the fabrication methods, cationic functionalized group reagent, and the effect of fller addition on membrane properties. PEEK is a thermoplastics polymer that possesses superior mechanical, thermal, and chemical stability. The basic development of PEEK-based AEM involves the process of attaching the cationic functionalized group, namely quaternary ammonium (QA), quaternary phosphonium (QP), and imidazolium (Im) groups onto the PEEK backbone. Up to the recent time, the chloromethylation-functionalization and acid-base blending methods are among the commonly used fabrication methods in developing PEEK-based AEM. The increase in the degree of functionalization (DF) caused the basic PEEK-AEM, namely QA-PEEK, QP-PEEK, and Im-PEEK to exhibit high hydroxide conductivity apart from the degradation in alkaline stability, mechanical property, and dimensional stability. The modifcation of the membranes performed through the addition of fller or ionic-crosslink between acid and base may improve the anion conduction pathway, alkaline stability, mechanical property and water retention property of the membrane due to the increase of the DF.