Reversible Zn electrodeposition enabled by interfacial chemistry manipulation for high-energy anode-free Zn batteries

Aqueous Zn batteries have attracted intensive interest in terms of the high safety and sustainable raw materials with low cost. However, the excess use of Zn anode greatly limits the practical energy density of batteries and arouses a threat to their real-life application. Here, a robust heterointerface composed of 0D metal nanodots and 2D metal carbide nanosheets with triple synergistic effects is designed to manipulate interfacial chemistry for anode-free Zn batteries. An interface of in situ anchoring ultrafine Sn nanodots on Na+ decorated MXene nanosheets is used as a model. The 2D Na-MXene promotes the Zn plating/stripping kinetics and homogenizes the distributions of electric field and ion flux. The high-affinity Zn binding sites of 0D Sn nanodots reduce the plating energy barrier and consequently manipulate the uniform Zn nucleation/growth. The in situ formed ZnF2 layer during Zn plating allows Zn ions to diffuse and shields side reactions. Consequently, the stable Zn plating/stripping with a high accumulated areal capacity of 5,000 mAh cm−2 is realized at high current density and plating capacity (10 mA cm−2∼20 mAh cm−2). Benefitting from triply synergistic effects derived from built cooperative interfaces, an anode-free Zn cell is constructed, proving ameliorative cyclic stability.