A multifunctional protective layer filled with 2D anionic nanosheets enabling a dendrite-free zinc anode

Metallic zinc (Zn) has been considered as an ideal anode material for aqueous batteries, but its development is hampered by the growth of Zn dendrites and side reactions with aqueous electrolytes. Herein, a multifunctional protective layer attached to Zn metal was fabricated by uniformly dispersing 2D Ti3O72− nanosheets in polyacrylonitrile (PAN) (denoted as PTO@Zn) to alleviate the above problems. The PAN layer can serve as an elastic H2O/O2-blocking layer to guard against corrosion and suppress intense dendrite evolution, and 2D Ti3O72− nanosheets with a negative charge confine the two-dimensional (2D) diffusion of Zn2+ along the lateral surface of the Zn anode, resulting in uniform deposition. This unique protective layer not only enables the anode to deliver a long lifespan of 2800 h at 0.5 mA cm−2 and 0.25 mA h cm−2 as well as 300 h at 5 mA cm−2 and 5 mA h cm−2, but also achieves an average coulombic efficiency (CE) of 98.4% over 500 cycles at 2 mA h cm−2. Moreover, the assembled PTO@Zn||MnO2 full cell exhibits remarkable rate performance and long-term cycling stability. This work provides a new strategy to prepare a multifunctional protective layer for highly stable Zn metal anodes.