Functionalized Separator with Integrated Mass Transfer Selectivity and Kinetics Regulation toward Durable Zn Anodes
Hangjun Ying, Shenwen Liu, Qinglong Zhao, Haonan Zheng, Mengya Wang, Chaowei He, Lucheng Cai, Lingjie Zhang, Huajun Tian, Gaorong Han, Wei‐Qiang Han
Abstract
The limited durability of Zn anodes in aqueous zinc-ion batteries (AZIBs) can largely be attributed to disordered ion transport and sluggish kinetics. In this work, a functional separator comprising bacterial cellulose functionalized with boehmite (BM/BC) is developed to regulate the ion flux, enhancing both the selectivity and kinetics of Zn 2+ transport. The BM/BC separator leverages strong coordination between its polar surface functional groups and electrolyte species to effectively anchor H 2 O molecules and SO 4 2– anions. This anchoring effect facilitates Zn 2+ desolvation and selective migration, yielding an exceptional Zn 2+ transference number of 0.81 and significant suppression of interfacial side reactions. Furthermore, the nucleophilic property of boehmite mitigates the strong adsorption of Zn 2+ by the cellulose chains, thereby conferring the BM/BC interfaces with low Zn 2+ diffusion barriers, which can accelerate Zn 2+ transport and homogenize the Zn 2+ flux. Consequently, the BM/BC separator effectively suppresses interfacial degradation of the Zn anode, as collectively demonstrated by the extended lifespan (>2900 h) in Zn||Zn symmetric batteries, stable cycling (>1000 cycles) in Zn||MnO 2 full batteries, and robust performance in pouch configurations. This work provides a feasible strategy and fundamental insights for the design of advanced separators for high-performance AZIBs.