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.

中文翻译：

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N 掺杂碳纳米片稳定的超细 MoS2 的界面 Mo-N 键合增强可实现超快耐用的钠离子半/满电池


二维层状材料的结构稳定性和 Na+ 扩散动力学对于提供高效的 Na+ 储存至关重要。在这里，少层 MoS2 纳米晶体锚定在 N 掺杂碳纳米片 （MoS2@NCs） 上，实现了快速的 Na+ 储存和较长的循环寿命。N 原子与 MoS2 纳米晶体和碳纳米片的紧密化学键 （Mo-N-C 键） 提高了 MoS2@NCs 的电子导电性和结构稳定性，而碳纳米片网络支持 MoS2@NCs 结构以减少体积效应，并为 Na+ 的快速扩散提供了表面主导的机制。密度泛函理论结果表明，具有 Mo-N-C 键的 MoS2@NCs 的低扩散势垒加速了 Na+ 转移动力学。因此，MoS2@NCs 在 20 A/g 时具有 307 mA h g-1 的优异倍率能力，并在 3,000 次循环中具有出色的长期稳定性。通过原位 EIS 和非原位 XRD 技术阐明了可逆的 Na+（去）插入行为。此外，组装好的 MoS2@NCs//Na3V2（PO4）3/C 全电池也表现出较高的可逆容量和良好的循环稳定性。这项工作为优化可用于高能量密度可充电 SIB 的二维分层材料开辟了一条新路线。