Preparation and characterization of anion exchange nano fillers and their effect on anion exchange membrane for anion exchange membrane fuel cells

Abstract

Fuel cells are electrochemical energy conversion devices which convert hydrogen-rich fuel into electricity directly, through an electro-chemical reaction with water being the only by-product. Among the various types of fuel cells, Anion Exchange Membrane Fuel Cells (AEMFCs) are notable as it possess many economic advantages, such as superior Oxygen Reduction Reaction (ORR) kinetics; its potential for use of non-Pt catalysts like Ag, Fe, Co and Ni; reduced fuel cross over and easier water management. The main drawback in the AEMFC is its low anionic conductivity of AEM. As a result, this technology in the present state is not commercially viable without the use of a membrane having high ionic conductivity along with remarkable physico-chemical and thermo-mechanical stabilities. Hence, there is a need to develop a suitable AEM, to overcome the above bottlenecks for their improved efficiency and durability of AEMFC. In most of the reported research studies, AEM composite membranes have been prepared using unfunctionalized nanofillers which improves the conductivity and stability of the membranes to some extent. In the present study, composite membranes have been fabricated using functionalized fillers and were investigated for their anion exchange characteristics in influencing the fuel cell efficiency. This research study addresses fabrication of composite anion exchange membranes for AEMFCs. Also, the Quaternary ammonium functionalised PSU (QPSU) was reinforced with various functionalised inorganic nano fillers to form composite membranes. For this study, three fillers were chosen namely, Santa Barbara Amphorous (SBA-15), Titanate Nano Tubes (TNT) and Polyhedral Oligomeric Silsesquioxane (POSS). The fillers were functionalized with two different ion exchange groups namely, quaternary ammonium and Imidazolium (using ionic liquids (IL)). Polysulfone was initially chloromethylated and then quaternized to produce an ideal membrane for AEMFC. newline