Regulating zinc deposition for dendrite-free aqueous zinc-ion batteries: A zincophilic chitosan polyelectrolyte hydrogel modified glass fiber separator

Rechargeable aqueous zinc-ion batteries (AZIBs) are a promising low-cost, safe, and eco-friendly alternative to lithium-ion batteries. However, the inhomogeneous deposition of metallic zinc on the anode and severe side reactions have hindered their large-scale application. In this study, we developed a zincophilic separator by coating and gelating natural chitosan (CS) onto one side of conventional glass fiber (GF) separators (named CSGF separator), which regulates zinc anode performance. The uniformly distributed CS hydrogel layer on GF anchors numerous water molecules and H+ in the electrolyte, inhibiting their activity and restraining side reactions. The functional groups of the CS-GF separator interact with zinc ions, promoting their diffusion and transfer kinetics and alleviating dendritic growth during zinc plating/stripping. Furthermore, the CS hydrogel layer improves the flatness of the GF separator and homogenizes its pore size distribution, guiding the uniform transport and deposition of zinc ions. The Zn||Zn symmetrical cells using CS-GF separators possess superior long life stability (1000 h at 2 mA cm-2/1 mA h cm-2), and high Coulombic efficiency of 99.6 %. Additionally, the rate capacity and cyclability of the Zn||NaV3O8 full cells with CS-GF separators are significantly improved. Therefore, the low-cost and scalable CS-GF separator holds tremendous great potential for practical application in AZIBs.