High performance and eco-friendly chitosan hydrogel membrane electrolytes for direct borohydride fuel cells

Novel, cost-effective, and environmentally benign polymer electrolyte membranes (PEMs) consisting of ionically cross-linked chitosan (CS) hydrogel is reported for direct borohydride fuel cells (DBFCs). The membranes have been prepared by ionic cross-linking of CS with sulfate and hydrogen phosphate salts of sodium. Use of Na2SO4 and Na2HPO4 as cross-linking agents in the preparation of ionically crosslinked CS hydrogel membrane electrolytes (ICCSHMEs) not only enhances cost-effectiveness but also environmental friendliness of fuel cell technologies. The DBFCs have been assembled with a composite of nickel and carbon-supported palladium as anode catalyst, carbon-supported platinum as cathode catalyst and ICCSHMEs as electrolytes-cum-separators. The DBFCs have been studied by using an aqueous alkaline solution of sodium borohydride as fuel in flowing mode using a peristaltic pump and oxygen as oxidant. A maximum peak power density of about 810 mW cm(-2) has been achieved for the DBFC employing Na2HPO4-based ICCSHME and operating at a cell temperature of 70 degrees C. (C) 2012 Elsevier B.V. All rights reserved.