Cyclodextrin templated nanoporous anion exchange membrane for vanadium flow battery application

• Published in: Journal of membrane science 2019-09, Vol.586, p.98-105
• Main Authors: Ma, Yanjiao, Li, Lv, Ma, Lingling, Qaisrani, Naeem Akhtar, Gong, Shoutao, Li, Panyue, Zhang, Fengxiang, He, Gaohong
• Format: Article
• Language: English
• Subjects: Anion exchange membrane; Cyclodextrin; Porous; Template; Vanadium flow battery
• ISSN: 0376-7388; 1873-3123
• DOI: 10.1016/j.memsci.2019.05.055

A β-cyclodextrin (β-CD) based template method is proposed for fabricating high performance nanoporous anion exchange membranes for vanadium flow batteries (VFBs). The β-CD template can be uniformly dispersed in hydroxyl modified polysulfone precursor membrane with a low degree of quaternization; removal of the template will result in the formation of AEMs with well controlled pore structure. This new template method is advantageous due to the hydrogen bonding between the β-CD and polymer so that aggregation of β-CD in the membrane can be minimized. The well dispersed β-CD is beneficial for fabricating porous AEM with small pores, and further for selective transport of protons and anions in the battery. The fabricated porous AEM has low IEC, high conductivity and low vanadium ions permeability. The VFB employing such a membrane showed a coulombic efficiency of 99% and an energy efficiency of 80% at 120 mA cm-2. This work demonstrates the synergistic effect of nanopore and imidazolium cation for high performance VFB membrane fabrication. •Hydroxyl polysulfone (HPSf-Im) with low quaternization degree (48%) was synthesized.•Porous AEM of HPSf-Im was fabricated with β-cyclodextrin (β-CD) template.•β-CD could be well dispersed in HPSf-Im and the AEM porosity was tunable.•The porous AEM showed high conductivity and ion selectivity at a low IEC.•High efficiencies of VFB were obtained with the porous AEM.