Poly (ionic liquid) filled and cross-linked bacterial cellulose-based organic-inorganic composite anion exchange membrane with significantly improved ionic conductivity and mechanical strength

The “trade-off” between high ionic conductivity and dimensional stability is a current challenge in preparation of anion-exchange membranes (AEMs). Here, the inorganic precursor tetraethyl silicate (TEOS) was used to induce silica mineralization on the surface of bacterial cellulose (BC) to obtain SiO2@BC. Then the CC of 3-(Trimethoxysilyl)propyl methacrylate (MPS) was modified on the SiO2@BC surface to fabricate MSiO2@BC porous substrate, followed by in situ filling and crosslinking polymerization with the CC of the cationic monomers (VBTAC) to prepare MSiO2@BC-PVD AEM. The inorganic component in the porous substrate not only enhanced the mechanical properties of AEM, but also induced to construct ordered ion transport channels within the membrane that effectively improved the ionic conductivity. The MSiO2@BC-PVD membrane simultaneously exhibited satisfactory ion conductivity (102 mS cm−1) and low swelling ratio (only 5.9%) at 80 °C. Moreover, the MSiO2@BC-PVD membrane showed a favorable tensile strength of 47.1 MPa, which was 95% higher than that of the pure BC/PVD membrane. More importantly, the maximum peak power density of alkaline direct methanol fuel cell assembled with MSiO2@BC-PVD membrane reached to 100 mW cm−2 at 80 °C. The present work opens a novel path to achieve AEMs with excellent ion conductivity and cell performances.