Biomass-Based Anion Exchange Membranes Using Poly (Ionic Liquid) Filled Bacterial Cellulose with Superior Ionic Conductivity and Significantly Improved Strength

Abstract

How to simultaneously improve the ionic conductivity and mechanical properties is a key problem facing currently used anion-exchange membranes (AEMs). Here, novel AEMs were prepared using quaternized bacterial cellulose (QBC) as a dual-functional substrate and then filled with a polymeric ionic liquid (poly(vinylbenzyl) trimethylammonium chloride, PVD) with high ion-exchange capacity through in situ polymerization and crosslinking. The dense quaternary ammonium groups grafted on the surface of BC nanofibers greatly increased the ionic conductivity, while the special three-dimensional network structure of BC significantly enhanced the tensile strength and chemical stability of the obtained PVD filled quaternized BC (QBC/PVD) membranes. The ionic conductivity of QBC/PVD membrane reached as high as 111 mS cm−1 at 80°C, which was 109% higher than that of the pure BC/PVD membrane (only 53 mS cm−1). Moreover, the QBC/PVD membrane exhibited extremely high dry strength of 72.3 MPa and satisfactory wet strength and flexibility, this membrane can hang a container containing 500 g of water when at fully hydrated state. The alkaline direct methanol fuel cell equipped with QBC/PVD output a peak power density of 64 mW cm−2, showing its great application potential as an AEM.

Keywords

• quaternized bacterial cellulose
• porous substrate
• ionic conductivity
• cell performance
• anion exchange membranes
• fuel cells