Titanium Nitride–Cellulose Nanofiber Composite Separator for Zn Anode Stability in Aqueous Batteries

Aqueous zinc-ion batteries (ZIBs) face significant challenges of Zn dendrite formation, electrode passivation, and corrosion. Herein, we introduce a composite separator composed of titanium nitride (TiN) and cellulose nanofiber (CNF), termed TN5, designed to enhance the performance of ZIBs. The TN5 separator, with a thickness of approximately 45 μm, combines low cost, high thermal stability, and flexibility. Experimental and theoretical analyses demonstrate that the TN5 separator improves Zn2+ ion diffusion and ensures uniform Zn plating, effectively mitigating dendrite and side reactions. Zn//Zn symmetric cells using the TN5 separator achieve exceptional cycling life spans of 2500 h at 0.5 mA cm–2 and 1000 h at 5 mA cm–2, significantly outperforming cells with CNF separators. Additionally, Zn//NVO full batteries with TN5 separators exhibit a superior discharge capacity and cycling stability. The enhanced performance is attributed to improved wettability, reduced concentration polarization, and the promotion of Zn (002) plane deposition. This study provides a comprehensive approach to developing high-performance, cost-effective separators for ZIBs, offering insights into the stabilization of Zn anodes and the advancement of aqueous zinc-ion battery technology.