Performance Variation of Flexible Polymer Electrolyte Fuel Cell with Ag Nanowire Current Collector under Torsion
This study shows the performance variation of flexible PEFC under torsion. Ag nanowires percolation network which can be stretched upto strain of 370% with less than 30 % increase of electrical resistance was adopted as material for current collector . Polydimethylsiloxane (PDMS) was used to fabricate bendable fuel cell stack. Cross-sectional sizes of flow channels on flow-field plates for anode and cathode were 1 x 1 mm2 and 2 x 1 mm2, respectively. Degrees of torsion were 0, 5, 10, 15 and 20°. The results showed that maximum power density of flexible PEFC decreases as torsion increases. From the previous results , it is speculated that compressive stress perpendicular to membrane-electrode assembly (MEA) decreased with increase of torsion degree. In order to investigate causes of performance loss, electrochemical impedance spectra were measured. It showed that ohmic and faradaic resistances of the cell increased with increase of torsion. It corresponds with the previous results that ohmic and faradaic resistances increase when normal compressive stress to MEA decrease. However, it was found that decreased percentage of maximum performance of the cell was less than 35 %, meaning that flexible PEFC can be used for flexible electronic devices if overdesigned.
This work was supported by the Global Frontier R&D Program on Center for Multiscale Energy System funded by the National Research Foundation under the Ministry of Education, Science and Technology, Korea (2011-0031569).
 I. Chang et al., Bendable polymer electrolyte fuel cell using highly flexible Ag nanowire percolation network current collectors, J. Mater. Chem. A, 2013, 1, 8541-8546.