Li Chao, Jiang Heming, Liu Pengxiang, Zhai Yi, Yang Xiuqin, Gao Longcheng, Jiang Lei
Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beihang University, Beijing 100191, P. R. China.
Key Laboratory of Bio-inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China.
J Am Chem Soc. 2022 Jun 1;144(21):9472-9478. doi: 10.1021/jacs.2c02798. Epub 2022 May 20.
Ion-exchange membranes (IEMs) convert osmotic energy into electricity when embedded in a reverse electrodialysis cell. IEMs with both high permselectivity and ionic conductivity are highly needed to increase the energy conversion efficiency. The ionic conductivity can be improved by increasing the content of immobile charge carriers, but it is always accompanied by undesirable permselectivity decrease due to excess swelling. Until now, breaking the permselectivity-conductivity tradeoff still has remained a challenge. Here, we demonstrate a membrane with the least ion-exchange capacity (∼10 mequiv g), generating an ultrahigh power density of 19.3 W m at a 50-fold concentration ratio. The membrane is made of a porphyrin-core four-star block copolymer (-BCP), forming the high-density helical porphyrin channels (∼10 cm) under the synergistic effect of BCP self-assembly and porphyrin π-π stacking. The porphyrin channel shows high Cl selectivity and high conductivity, benefiting high-performance osmotic energy conversion. This economic and facile membrane design strategy provides a promising approach to developing a new generation of IEMs.
离子交换膜（IEMs）嵌入反向电渗析电池时可将渗透能转化为电能。为提高能量转换效率，急需兼具高选择透过性和离子传导性的离子交换膜。通过增加固定电荷载体的含量可提高离子传导性，但由于过度溶胀，往往会导致不理想的选择透过性降低。到目前为止，打破选择透过性与传导性之间的权衡仍然是一项挑战。在此，我们展示了一种离子交换容量最低（约10 mequiv g）的膜，在50倍浓度比下可产生19.3 W m的超高功率密度。该膜由卟啉核四星嵌段共聚物（-BCP）制成，在BCP自组装和卟啉π-π堆积的协同作用下形成高密度螺旋卟啉通道（约10 cm）。卟啉通道具有高Cl选择性和高传导性，有利于实现高性能渗透能转换。这种经济简便的膜设计策略为开发新一代离子交换膜提供了一种很有前景的方法。
