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Bilayer Anion-Exchange Membrane with Low Borohydride Crossover and Improved Fuel Efficiency for Direct Borohdyride
Xingxing Li1, Haodong Chen1, Wen Chu2
1College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018, P. R. China.
Abstract:
The development of membranes with low fuel crossover and high fuel efficiency is a key issue in direct borohydride fuel cells (DBFCs). In previous work, we produced a poly(vinyl alcohol) (PVA)-anion-exchange resin (AER) membrane with a low fuel crossover and a low fuel efficiency by introducing Co ions. In this work, a bilayer membrane was designed to improve the fuel efficiency and cell performance. The bilayer membrane was prepared by casting a PVA-AER wet gel onto the partially desiccated Co-PVA-AER gel. The bilayer membrane showed a borohydride permeability of 1.34 × 10-6 cm2·s-1, which was even lower than that of the Co-PVA-AER membrane (1.98 ×10-6 cm2·s-1) and the PVA-AER membrane (2.80 × 10-6 cm2·s-1). The DBFC using the bilayer membrane exhibited a higher fuel efficiency (37.4%) and output power (1.73 Wh) than the DBFCs using the Co-PVA-AER membrane (33.3%, 1.27 Wh) and the PVA-AER membrane (34.3%, 1.2 Wh). Furthermore, the DBFC using the bilayer membrane achieved a peak power density of 327 mW·cm-2, which was 2.14 times of that of the DBFC using the PVA-AER membrane (153 mW·cm-2). The drastic improvement benefited from the bilayer design, which introduced an interphase to suppress fuel crossover and avoided unnecessary borohydride hydrolysis.
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