Engineering Anisotropically Curved Nitrogen-Doped Carbon Nanosheets with Recyclable Binary Flux for Sodium-Ion Storage

As a low-cost substitute of graphene and graphene derivatives, 2D carbon nanosheets are considered to be attractive materials for high-performance electrochemical energy-storage devices. Nevertheless, the lack of cost-effective and green preparation methods still greatly impedes the application of 2D carbon nanosheets in sodium-ion batteries. Herein, an environmental friendly and versatile strategy is proposed to engineer anisotropically curved nitrogen-doped carbon nanosheets (CNCNs) derived from biosources with hydrosoluble and recyclable flux. After undergoing serious corrosion from the LiCl/KCl binary flux, the resulting CNCNs possess high structural stability. Notably, the CNCNs also possess a rational specific surface area, open porous structure, and abundant accessible edges, which can shorten the ion-diffusion path, provide abundant accessible active sites, and result in less charge-transfer impedance and excellent sodium-ion diffusion coefficient (8.9×10⁻¹⁰ cm² s⁻¹). As a consequence, CNCN electrodes can deliver a high specific capacity of 361.6 mAh g⁻¹ at 50 mA g⁻¹. Such architecture provides a promising structural platform for the fabrication of 2D carbons for highly reversible and high capacity sodium-ion batteries.