Layered MoS are promising anode materials due to the applicable interlayer spacing (0.62 nm) and high theoretical specific capacity (669mAh g). Nevertheless, the low electric conductivity, large structure variation and sluggish ionic kinetics result in rapid capacity decay and suboptimal cycle performance of MoS-based sodium-ion batteries (SIBs). Here, the two-step methodology was used to grow MoS sheets on the surface of N-doped carbon fibers with CoS nanoparticles encapsulated in. The obtained MoS@CoS@CNFs exhibit a distinctive hierarchical structure, which increases the electrode-electrolyte interface, thereby minimizing the diffusion distance of Na. Experiment and calculation results demonstrates that the incorporation of CoS not only enhances the ion mobility and pseudocapacitance contribution of the electrode material, but also amplifies its conductivity and adsorption energy of Na, ultimately elevating the rate performance and ensuring long cycle stability of SIBs. Consequently, the MoS@CoS@CNFs composite enabled a commendable capacity of 494.5 mAh g after 700 cycles at 0.5 A g. Impressively, when the current density was increased to 2 A g, it reserved a capacity of 310 mAh g for 2000 cycles. To encapsulation of CoS nanoparticles in the MoS@CoS@CNFs composite promotes the stability of the anodes and boosts durable Na storage, making it a promising method for designing high performance SIBs.

中文翻译：

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CoS2纳米颗粒封装促进稳定的MoS2@CoS2@CNFs异质结构和持久的钠离子存储


由于适用的层间距（0.62nm）和高理论比容量（669mAh g），层状MoS是有前途的负极材料。然而，低电导率、大的结构变化和缓慢的离子动力学导致MoS2基钠离子电池（SIB）的快速容量衰减和次优循环性能。在这里，采用两步法在封装有 CoS 纳米颗粒的 N 掺杂碳纤维表面生长 MoS 片。获得的 MoS@CoS@CNF 表现出独特的分层结构，增加了电极-电解质界面，从而最小化Na的扩散距离。实验和计算结果表明，CoS的引入不仅增强了电极材料的离子迁移率和赝电容贡献，而且放大了其电导率和Na吸附能，最终提高了SIB的倍率性能并确保了长循环稳定性。因此，MoS@CoS@CNFs 复合材料在 0.5Ag 下循环 700 次后具有令人称赞的 494.5 mAh g 的容量。令人印象深刻的是，当电流密度增加到2Ag时，2000次循环后仍保留310 mAh g的容量。将 CoS 纳米颗粒封装在 MoS@CoS@CNFs 复合材料中可提高阳极的稳定性并增强持久的 Na 存储，使其成为设计高性能 SIB 的有前途的方法。