Multiblock copolymer based anion exchange membranes and ionomers

Abstract

Anion exchange membranes (AEMs) have been a subject of research as hydroxide conducting polymer electrolytes in electrochemical devices like fuel cells and electrolyzers in recent years due to the alkaline conditions facilitating reaction kinetics and allowing for non-precious metal catalysts, which greatly reduces the cost. However, the wide-scale commercialization of the AEMs is impeded by the low ionic conductivity, high water uptake, poor alkaline stability, and poor mechanical properties of current materials. The primary objective of this study is to create anion exchange membranes and ionomers with improved properties, including high ionic conductivity (i.e. greater than 100 mS/cm), excellent chemical stability under alkaline conditions, and low water uptake for better dimensional stability, compared to existing materials in the applications of fuel cells and electrolyzers. To achieve this objective, several new structures for polymeric anion exchange membranes were designed, and the corresponding structure-morphology-property relationship was investigated: (1) multiblock copolymer with partial fluorination and long head-group tethers, (2) different number of ionic groups in hydrophilic segments, (3) long alkyl chain tethered quaternary trimethylammonium, quinuclidium, and phosphonium cations, (4) anion exchange ionomers performance in fuel cell and electrolyzer.