Unlocking the potential of ultra-thin two-dimensional antimony materials: Selective growth and carbon coating for efficient potassium-ion storage

Abstract

Antimony-based anodes have attracted wide attention in potassium-ion batteries due to their high theoretical specific capacities (∼660 mA h g−1) and suitable voltage platforms. However, severe capacity fading caused by huge volume change and limited ion transportation hinders their practical applications. Recently, strategies for controlling the morphologies of Sb-based materials to improve the electrochemical performances have been proposed. Among these, the two-dimensional Sb (2D-Sb) materials present excellent properties due to shorted ion immigration paths and enhanced ion diffusion. Nevertheless, the synthetic methods are usually tedious, and even the mechanism of these strategies remains elusive, especially how to obtain large-scale 2D-Sb materials. Herein, a novel strategy to synthesize 2D-Sb material using a straightforward solvothermal method without the requirement of a complex nanostructure design is provided. This method leverages the selective adsorption of aldehyde groups in furfural to induce crystal growth, while concurrently reducing and coating a nitrogen-doped carbon layer. Compared to the reported methods, it is simpler, more efficient, and conducive to the production of composite nanosheets with uniform thickness (3–4 nm). The 2D-Sb@NC nanosheet anode delivers an extremely high capacity of 504.5 mA h g−1 at current densities of 100 mA g−1 and remains stable for more than 200 cycles. Through characterizations and molecular dynamic simulations, how potassium storage kinetics between 2D Sb-based materials and bulk Sb-based materials are explored, and detailed explanations are provided. These findings offer novel insights into the development of durable 2D alloy-based anodes for next-generation potassium-ion batteries.