Dendrites-Free Zn Metal Anodes Enabled by an Artificial Protective Layer Filled with 2D Anionic Nanosheets

Metallic zinc (Zn) has been considered to be an ideal anode material for aqueous batteries, but is impeded by the growth of Zn dendrites and its side reactions with an aqueous electrolyte. Here, it is reported that an artificial protective layer filled with novel 2D Zn²⁺ adsorbed Sb₃ P₂ O₁₄ ^3- (denoted as Zn-Sb₃ P₂ O₁₄ ) nanosheets provide an effective route to mitigate the above challenging problems. The Zn-Sb₃ P₂ O₁₄ protection layer not only avoids the direct contact with the aqueous electrolyte to suppress the side reactions but also allows for Zn-ions to pass through the protection layer rapidly. Moreover, the 2D Sb₃ P₂ O₁₄ ^3- skeleton with negative charge also confines the 2D diffusion of Zn-ion along the lateral surface of Zn anode, resulting in a uniform electron-deposition. This unique protection layer not only enables dendrite-free Zn plating/stripping with an average Coulombic efficiency of 99.2% for 200 cycles, but also sustains the symmetric Zn||Zn cell over 1300 h at 1 mA cm^-2 and 1 mAh cm^-2 as well as for 450 h at 10 mA cm^-2 and 10 mAh cm^-2 . Such advantages bring high reversibility to full Zn batteries with MnO₂ cathodes, which deliver a discharge capacity of 111.7 mAh g^-1 after 1000 cycles.