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

Abstract 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.