Blends and composites of sulphonated poly styrene ethylene butylene poly styrene for PEM and direct methanol fuel cells

Abstract

In general, fuel cells use hydrogen as fuel and oxygen as oxidant. In theory, any gases capable of being electrochemically oxidized or reduced can be used as fuel and oxidant in a fuel cell. In spite of various research studies, the commercializations of fuel cells are still facing hiccups. One such hiccup is the cost and environmental issues of Nafion electrolyte which is one of the critical components of the fuel cell. The aim of the present research work is to synthesize and characterize polymer electrolyte membranes that can act as a replacement for Nafion. With this concept in mind, a tri block polymer, poly styrene ethylene butylene polystyrene (PSEBS) is considered for the fabrication of electrolytes. Nine series of electrolyte membranes were fabricated and characterized in the current study. It includes blending of sulphonated poly styrene ethylene butylene poly styrene (SPSEBS) with polysulphone (PSU), polyvinylidene fluoride (PVDF), poly styrene ethylene butylene poly styrene (PSEBS), sulphonated polysulfone (SPSU) and composite membranes of SPSEBS with boron phosphate (BPO4), zirconium phosphate (ZrPO4) and phosphoric acid (H3PO4). Two other interesting studies involved the preparation of special membranes by layer by layer assembly of sulphonated polysulphone and aminated polysulphone on SPSEBS and SPSEBS crosslinked with glutaraldehyde. Collectively, it may be inferred that various blends, composite, LBL membranes and crosslinked membranes showed good proton conduction which is very important for an electrolyte in fuel cell. They showed excellent thermal stability, adequate mechanical properties and appreciable durability. There is a good compatibility among the constituents in all the blend and composite membranes as revealed by XRD and SEM. From the current investigation, it may be concluded that all the developed blend and composite membranes are suitable for both DMFC and PEMFC operation. In particular, the composite membranes are more promising for PEMFC and the LBL membranes for DMFC.