posted on 2014-05-28, 00:00authored byKeun-Hwan Oh, Dongju Lee, Min-Ju Choo, Kwang Hyun Park, Seokwoo Jeon, Soon Hyung Hong, Jung-Ki Park, Jang Wook Choi
We report boron nitride nanoflakes
(BNNFs), for the first time, as a nanofiller for polymer electrolyte
membranes in fuel cells. Utilizing the intrinsic mechanical strength
of two-dimensional (2D) BN, addition of BNNFs even at a marginal content
(0.3 wt %) significantly improves mechanical stability of the most
representative hydrocarbon-type (HC-type) polymer electrolyte membrane,
namely sulfonated poly(ether ether ketone) (sPEEK), during substantial
water uptake through repeated wet/dry cycles. For facile processing
with BNNFs that frequently suffer from poor dispersion in most organic
solvents, we non-covalently functionalized BNNFs with 1-pyrenesulfonic
acid (PSA). Besides good dispersion, PSA supports efficient proton
transport through its sulfonic functional groups. Compared to bare
sPEEK, the composite membrane containing BNNF nanofiller exhibited
far improved long-term durability originating from enhanced dimensional
stability and diminished chronic edge failure. This study suggests
that introduction of properly functionalized 2D BNNFs is an effective
strategy in making various HC-type membranes sustainable without sacrificing
their original adventurous properties in polymer electrolyte membrane
fuel cells.