Enhancing proton conduction under low humidity by incorporating core-shell polymeric phosphonic acid submicrospheres into sulfonated poly(ether ether ketone) membrane

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• 作者：Lingli Nie^a ; Jingtao Wang^a ; Tao Xu^a ; Hao Dong^a ; Hong Wu^a ; ^b ; Zhongyi Jiang^a ; ^{zhyjiang@tju.edu.cn}
• 关键词：Core&ndash ; shell polymeric phosphonic acid submicrosphere ; Sulfonated poly(ether ether ketone) ; Water retention ; Proton conduction ; Direct methanol fuel cell membrane
• 刊名：Journal of Power Sources
• 出版年：2012
• 期刊代码：58_03787753
• 类别：ce
• 出版时间：1 September, 2012
• 卷：213
• 期：Complete
• 页码：1-9
• 文件大小：1102 K

摘要

Polymeric phosphonic acid submicrospheres (PPASs) with carboxylic acid cores and phosphonic acid shells are synthesized by distillation-precipitation polymerization. The structure and composition of PPASs are confirmed by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and energy dispersive X-ray (EDX). The PPASs are then incorporated into sulfonated poly(ether ether ketone) (SPEEK) to fabricate composite membranes for direct methanol fuel cells (DMFCs). The incorporated PPASs enlarge the ion-channel size of the composite membranes as testified by small-angle X-ray scattering (SAXS), affording significantly enhanced water uptake and water retention. Compared with the membrane containing the polymeric carboxylic acid submicrospheres (PCASs), the PPASs-filled membrane exhibits higher proton conductivity owing to the higher water uptake and water retention of the PPASs and stronger acidity of phosphonic acid. The composite membrane with 15聽wt.%PPASs displays the highest proton conductivity of 0.0187聽S聽cm^鈭? at room temperature and 100%relative humidity (RH). At the RH as low as 20%, this membrane acquires a proton conductivity of 0.0066聽S聽cm^鈭?, 5 times higher than that of the SPEEK control membrane (0.0011聽S聽cm^鈭?) after 90聽min testing, at 40聽掳C.