A New Scalable Preparation of Metal Nanosheets: Potential Applications for Aqueous Zn-Ion Batteries Anode

2D metal nanosheets are attractive for various applications stemming from the intriguing characteristics related with their dimensionality; however, their effective and scalable preparation remains a great challenge. Herein, a scalable preparation process of relatively active metal nanosheets (e.g., Zn, Al, and Cu) with the thickness down to several nanometers at low cost is demonstrated, which involves an initial self-folding-rolling step followed by the subsequent ultrasonication to exfoliate them without any etching step. The native oxide on the surface of the metals, which acts as a barrier between the adjacent metal layers, plays a special role in enabling the successful preparation of 2D metal nanosheets. As a demonstration for their practicability, a hierarchical Zn anode, which is constructed by the Zn microsheets coated with carbon (Zn MS@C) via in situ carbonization of carboxymethylcellulose (CMC) binder, is successfully implemented as anode for rechargeable aqueous Zn-ion batteries. When applied in symmetrical battery, the Zn MS@C delivers a long lifespan of over 800 h at 0.2 mA cm⁻² with a capacity of 0.1 mA h cm⁻². Importantly, the full battery of MnO₂ || Zn MS@C also performs a high discharge capacity of 217.4 mA h g⁻¹ after 140 cycles at 300 mA g⁻¹.