Triblock copolymer anion exchange membranes bearing alkyl-tethered cycloaliphatic quaternary ammonium-head-groups for fuel cells

• Published in: Journal of power sources 2017-10, Vol.365, p.282-292
• Main Authors: Lin, Chen Xiao, Wang, Xiu Qin, Li, Ling, Liu, Fang Hua, Zhang, Qiu Gen, Zhu, Ai Mei, Liu, Qing Lin
• Format: Article
• Language: English
• Subjects: Anion exchange membranes; Cycloaliphatic quaternary ammonium; Fuel cells; Triblock copolymer; Well-connected hydrophilic domains
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2017.08.100

To explore highly conductive and alkaline stable anion exchange membrane (AEM) materials, triblock copolymers bearing alkyl-tethered cycloaliphatic quaternary ammonium-head-groups are prepared via nucleophilic substitution, Friedel-Crafts acylation, ketone reduction and Menshutkin reaction. The designed triblock copolymers composed of quaternized poly(phenylene oxide) segments and poly(ether sulfone) segments are responsible for the microphase separated morphology and well-connected ion domains, as confirmed by transmission electron microscopy. The highest conductivity, up to 105.1 mS cm−1 at 80 °C is achieved for the AEM with ionic exchange capacity (IEC) of 1.81 meq g−1. Furthermore, the AEMs show robust alkaline stability due to the alkyl-tethered cation-head-groups structure. High retention of hydroxide conductivity (88.9%) and IEC (91.2%) is observed for the AEMs via degradation test in a 1 M aqueous KOH solution at 80 °C for 480 h. Based on the AEM with high conductivity, a H2/O2 fuel cell achieves a peak power density of 176.5 mW cm−2 (80 °C) at a current density of 500 mA cm−2. [Display omitted] •Triblock copolymer AEMs bearing alkyl-tethered head-groups were prepared.•Well-connected ionic domains were formed in the membranes.•The AEMs exhibited a highest conductivity of 105.1 mS cm−1 at 80 °C.•The AEMs have good thermal stability and robust alkaline stability.