Huang Zequan, Zhu Danyi, Ma Mingjie, Zhao Bing, Liang Jiazhen, Zhang Liang, Chen Chao, Liu Mengjiao, Gao Congjie, Huang Fei, Xue Lixin
College of Chemical Engineering, State Key Laboratory Breeding Base of Green Chemistry Synthesis Technology, Zhejiang University of Technology, Hangzhou, Zhejiang, 310014, China.
College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, Zhejiang, 325035, China.
Small. 2024 Nov 30:e2408159. doi: 10.1002/smll.202408159.
The degradation of fixed cationic groups in most anion exchange membranes (AEMs) under alkaline environments limits their durability for alkaline water electrolysis (AWE). Ion-solvating membranes (ISMs) have emerged as a promising alternative to address this issue. Herein, a cationic group-free ion solvating membrane in a free-standing gel form (ISM-PBI-FG) is presented, created through a sol-to-gel transformation process followed by KOH imbibing. This approach yields a 3D porous microstructure composed of entangled polybenzimidazole (PBI) nanofibrils, achieving 89% porosity, which enables ultrahigh alkali uptake (346% in 6 M KOH) and exceptional ionic conductivity (763 mS cm at 80 °C). The absence of cationic groups avoids the attack by OH, thus ensures good alkaline stability with a conductivity retention rate of 91.6% over a 3120 h ex situ test in 6 M KOH. The resulting membrane delivered outstanding AWE performance with current densities of 5.5 A cm using platinum-group-metal (PGM) catalysts and 2.2 A cm using PGM-free catalysts at 2.0 V. Notably, the in situ electrolyzer device based on ISM-PBI-FG offers extensive operational flexibility ranging from 40-100 °C and demonstrates record durability in concentrated alkaline conditions, with a voltage decay rate of only 23.5µV h, outperforming most reported AEMs and ISMs.
在碱性环境下，大多数阴离子交换膜（AEM）中固定阳离子基团的降解限制了它们在碱性水电解（AWE）中的耐久性。离子溶剂化膜（ISM）已成为解决这一问题的一种很有前景的替代方案。在此，我们展示了一种独立凝胶形式的无阳离子基团离子溶剂化膜（ISM-PBI-FG），它是通过溶胶-凝胶转变过程，然后浸入KOH制成的。这种方法产生了一种由缠结的聚苯并咪唑（PBI）纳米纤维组成的三维多孔微观结构，孔隙率达到89%，实现了超高的碱吸收量（在6 M KOH中为346%）和出色的离子电导率（80°C时为763 mS/cm）。无阳离子基团避免了OH的攻击，从而确保了良好的碱性稳定性，在6 M KOH中进行3120小时的异位测试后，电导率保留率为91.6%。使用铂族金属（PGM）催化剂时，所得膜在2.0 V下的电流密度为5.5 A/cm²，使用无PGM催化剂时为2.2 A/cm²，展现出出色的碱性水电解性能。值得注意的是，基于ISM-PBI-FG的原位电解槽装置在40-100°C范围内具有广泛的操作灵活性，并在浓碱性条件下表现出创纪录的耐久性，电压衰减率仅为23.5μV/h，优于大多数已报道的AEM和ISM。
