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

Abstract

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 CS-GF 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.