Anion exchange membrane and its composites for fuel cell applications

Abstract

The problem of global climate change caused by greenhouse gases and environmental pollution has forced researchers and manufacturers to search for alternative sources of energy. This thesis addresses the fabrication and development of alkaline membrane fuel cells (AMFCs) and direct methanol alkaline membrane fuel cells (DMAMFCs). The AMFC and DMAMFC are low temperature fuel cells, in which an anion exchange membrane (AEM) is used as an electrolyte. Inspite of many research studies, the commercialization of fuel cells is still facing hiccups. Among the stumbling blocks the cost and environmental issues in proton exchange membrane fuel cells (PEMFCs) using Nafion as the electrolyte membrane are the major concerns. In this present study, two polymers were selected namely poly styrene poly styrene [PSEBS] and polysulfone [PSU] to prepare anion exchange membrane. PSEBS is hydrocarbon based triblock polymer and composed of two styrene end blocks and one ethylene butylene center block that is a thermoplastic phase dispersed in an elastomeric matrix. PSEBS is therefore a thermoplastic elastomer with excellent mechanical, chemical and thermal stabilities. Polysulfone is a commercially available aromatic polymer. Hence these two polymers are identified in this present study. The FTIR and XRD studies confirmed a good mix-up of the constituent polymers in the resulting composite. The SEM and TEM images indicated dense, uniform membranes and good compatibility among the constituents. Conclusively, it may be inferred that various composites showed good ionic conductivity which is a very important characteristic for an electrolyte in a fuel cell. They also showed excellent thermal stability, adequate mechanical properties and appreciable stability. There was good compatibility among the constituents in all the composite membranes as revealed by XRD and SEM. From the current investigation, it may be concluded that all the developed composite membranes are suitable for both AMFC and DMAMFC operations. newline newline newline