Preparation and Properties of Novel Sulfonated Pentablock Copolymer (sPBC) Membrane for PEM Fuel Cell

Abstract

Fuel cell is considered as a promising alternative energy device to convert chemical energy into electrical energy. Proton exchange membrane fuel cell (PEMFC) has special attention, in all types of fuel cell, due to its high power density, low temperature start-up, portable and cleanliness. Nafion (perfluorosulfonic acid) is successfully used as membrane for PEMFC but because of its limitations other alternative materials are also explored. In aromatic hydrocarbon, especially block copolymer, has been very attractive for membrane material due to its implicit properties in the field of ionic transportation, water retention and repulsion. In this work, sulfonated pentablock copolymer (sPBC, NexarTM) has been worked out as an alternative to Nafion for PEMFC membrane. The sPBC membrane was developed by casting method. Material properties were analyzed with the help of FTIR, XRD and TGA. Membrane characterization test for fuel cell such as water uptake, ion exchange capacity (IEC) and proton conductivity was carried out and then compared with Nafion. Proton conductivity at different temperatures was also evaluated, and it was found that Nexar has higher conductivity than Nafion. Conductivity–temperature relationship is used to calculate activation energy, and it was found that Nexar has lower activation energy than Nafion. Transport model for proton was also predicted using activation energy.