Poly(fluorenyl alkylene)-based anion exchange membranes for high-performance water electrolysis

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2024-01, Vol.480, p.148225, Article 148225
• Main Authors: Ma, Yichang, Li, Lingjing, You, Xueqing, Lin, Huiting, Yi, Guiqin, Su, Xiangyu, Zhu, Aimei, Liu, Qinglin, Zhang, Qiugen
• Format: Article
• Language: English
• Subjects: Anion exchange membrane; Hydrogen production; Poly(aryl alkylene); Water electrolysis
• ISSN: 1385-8947
• DOI: 10.1016/j.cej.2023.148225

[Display omitted] •The AEMs have curved-straight and short-long interlaced polymer structures.•The AEMs show a high OH– conductivity (155.7 mS cm−1) and durable alkaline stability.•A high current density of 4.9 A cm−2 @ 2.0 V is obtained in the AEMWE at 80 °C.•The 2200 h AEMWE shows a low voltage rising rate of 77 μV h−1 (1.0 A cm−2, 80 °C).•The QA groups were only degraded by 13.7 % after 2200 h of in-situ AEMWE testing. Durable and high-performance anion exchange membranes (AEMs) are a pivotal issue for the industrial application of AEM water electrolysis (AEMWE). In this study, a series of poly(fluorenyl alkylene) copolymers with different contents of biphenyls and p-terphenyls are synthesized for the high-performance AEMWE. The resulting AEM with an appropriate content of p-terphenyl well facilitates the microphase separation to get a well-defined microstructure that effectively improves the ionic conductivity and reduces the swelling ratio. The AEM with 20% p-terphenyl possesses an OH– conductivity of 155.7 mS cm−1, a water uptake of 128.7%, and a swelling ratio of 33.8% at 80 °C. Moreover, it also shows durable alkaline stability and retains 83.5% of cationic groups after immersing in 5 M NaOH at 80 °C for 1440 h. The assembled AEMWE cell achieves an excellent current density of 4.9 A cm−2 at 2 V in 1 M KOH (80 °C) and 2200 h of long-term constant current (1 A cm−2) operation with a low voltage rising rate of 77 μV h−1. After this long-term operation, only 13.7% of cationic groups are degraded in the AEM, showing excellent in-situ durability. Therefore, the developed AEMs should have great potential for applications in the AEMWE.