Interfacial Mo-N bonding enhancement of N-doped carbon nanosheets-stabilized ultrafine MoS2 enable ultrafast and durable sodium ion half/full batteries

Abstract

The structural stability and Na⁺ diffusion kinetics of two-dimensional layered materials are critical to deliver efficient Na⁺ storage. Here, few-layer MoS₂ nanocrystals were anchored on N-doped carbon nanosheets (MoS₂@NCs), which realizes fast Na⁺ storage and long cycle life. The tight chemical bonding (Mo-N-C bonds) of N atom to MoS₂ nanocrystals and carbon nanosheets improves the electronic conductivity and the structural stability of MoS₂@NCs, while the carbon nanosheets network supports the MoS₂@NCs structure to reduce the volume effect and provides a surface-dominated mechanism for fast Na⁺ diffusion. Density functional theory results show that the low diffusion barrier of MoS₂@NCs with Mo-N-C bonds accelerates the Na⁺ transfer kinetics. Consequently, MoS₂@NCs possesses superior rate capability of 307 mA h g⁻¹ at 20 A/g and excellent long-term stability over 3,000 cycles. The reversible Na⁺ (de)insertion behavior is elucidated through in-situ EIS and ex-situ XRD technology. In addition, the assembled MoS₂@NCs//Na₃V₂(PO₄)₃/C full cell also exhibits a high reversible capacity and good cycle stability. This work opens a new route for optimizing two-dimensional layered materials that can be used for high energy density rechargeable SIBs.