Microstructural Tuning of High-Performance Bacterial Cellulose Anion Exchange Membranes via Constrained In Situ Polymerization and Double Chemical Cross-Linking

High electrochemical and durability anion exchange membranes (AEMs) are a vital material for Flexible zinc-air batteries (F-ZAB) and AEM water electrolysis (AEMWE) to achieve green economy and environmental protection. However, the existing AEMs possess the disadvantages of a complicated preparation process, poor homogeneity, and unsatisfactory electrochemical performance. Here, a novel alkaline exchange membrane is synthesized using bacterial cellulose (BC) as the matrix, incorporating constrained in situ Poly (diallyldimethylammonium chloride) (PDDA) polymerization and double chemical cross-linking techniques. By adjusting the microstructure, a unique long-range order and dense internal structure to address the issue of loose bonding between PDDA and BC is established and achieve the purpose of rapid OH- conduction. The membranes exhibit excellent application properties, with excellent ionic conductivity (145.12 mS cm-1) and superb mechanical strength (73.26 MPa). Consequently, the membrane is assembled into the F-ZAB, and the unprecedented power density of 258.7 mW cm-2 can be achieved at room temperature. Moreover, the membrane also can reach 3.0 A cm-2 at 2.3 V, indicating good prospects in the field of water electrolysis in 6 m KOH. The approach paves a new path for manufacturing AEMs for green energy and environmental applications. The membranes are fabricated through in situ polymerization, incorporating varying concentrations of Poly (diallyldimethyl-ammonium chloride), followed by modification using double cross-linking techniques. The BC/PDDA-G1.5-B6.75 membrane exhibits a sigma OH- of 145.12 mS cm-1, a current density of up to 3.0 A cm-2 using electrolytic wate and an excellent power density of 258.7 mW cm-2 in flexible zinc-air batteries. image