Reducing hydroxide transport resistance by introducing high fractional free volume into anion exchange membranes

• Published in: Journal of membrane science 2024-05, Vol.701, p.122769, Article 122769
• Main Authors: Yuan, Caili, Chen, Yuhang, Lu, Xiaoli, Ma, Xiaoqin, Yuan, Wei, Zhu, Xun, Chen, Baoshu, Wang, Jianchuan, Wei, Zidong
• Format: Article
• Language: English
• Subjects: anion exchange; Anion exchange membrane; electric potential difference; electrolysis; electrolytes; Fuel cell; fuel cells; Hydroxide transport resistance; Hyperbranched structure; polymers; Water electrolysis
• ISSN: 0376-7388; 1873-3123
• DOI: 10.1016/j.memsci.2024.122769

The efficiency of ion transport in solid polyelectrolytes is significantly hindered by tight polymer chain entanglement compared to that in liquids. In this study, a series of hyperbranched poly(aryl piperidinium) anion exchange membranes (AEMs) with 1,3,5-triacetylbenzene as a branching point were synthesized. The hyperbranched structure results in weaker chain entanglement and a larger interchain correlation distance, leading to a higher fractional free volume, thereby greatly reducing ion transport resistance. Consequently, a remarkably higher OH− conductivity of the as-prepared hyperbranched AEM (296 mS cm−1) is achieved compared to that of non-hyperbranched AEMs (180 mS cm−1). Furthermore, the hyperbranched AEMs exhibit excellent fuel cell and water electrolysis performance, with a peak power density of 1.53 W cm−2 in AEMFCs and a current density of 1 A cm−2 at a voltage of 2 V in AEMWEs, respectively. [Display omitted] •Hyperbranched poly(aryl piperidinium) AEMs are prepared.•Weak chain entanglement and large interchain correlation distance increase the FFV.•High FFV reduces the ion transport resistance in AEM.•Excellent OH− conductivity and good AEMFC and AEMWE performance are achieved.