A Dual-Confinement Strategy Based on Encapsulated Ni-CoS2 in CNTs with Few-Layer MoS2 Scaffolded in Rgo for Boosting Sodium Storage Via Rapid Electron/ion Transports

Owing to their high theoretical capacity, transition metal sulfides have received tremendous attention as potential anode materials for sodium-ion batteries (SIBs). Accelerating the charge migration and alleviating the volume expansion of anode materials is critical for improving the electrochemical performance of SIBs. Herein, a composite of Ni-CoS2⊂CNTs/MoS2/rGO (DC-CNTs/M) via dual-confinement strategy is constructed as anode material for SIBs. Few-layer MoS2 was prepared via the layered confinement of layered double hydroxides, which could accelerate the transfer of Na+. Moreover, in-situ-grown carbon nanotubes (CNTs) not only improve the electronic conductivity of the material but also encapsulate Ni-CoS2 can alleviate volume expansion during the charging/discharging process, further maintaining electrode integrity and stability. Therefore, the DC-CNTs/M electrode delivers attractive cycling stability (592.6 mAh g−1 at 0.5 A g−1 over 200 cycles) and high rate performance (486.2 mAh g−1 at 5.0 A g−1). EXAFS and XANES analyses were performed to investigate the chemical bond and coordination environments between the atoms, demonstrating the strong interactions between metal sulfides in the DC-CNTs/M composite. In addition, ex-situ XRD shows that the structural changes during the Na+ insertion/extraction processes are highly reversible. Consequently, the dual-confinement strategy would provide a unique approach to the rational design of high-performance anodes for SIBs.