Double-layer carbon protected CoS 2 nanoparticles as an advanced anode for sodium-ion batteries.

Cobalt disulfides with high theoretical capacity are regarded as appropriate anode materials for sodium ion batteries (SIBs), but their intrinsically low conductivity and large volume expansion lead to a poor electrochemical performance. In this work, graphitic carbon coated CoS ₂ nanoparticles are encapsulated in bamboo-like carbon nanotubes by pyrolysis and sulfidation process. Graphitic carbon can improve the electrical conductivity and prevent the agglomeration of CoS ₂ nanoparticles. Meanwhile, bamboo-like carbon nanotubes can serve as conductive skeleton frames to provide rapid and constant transport pathways for electrons and offer void space to buffer the volume change of CoS ₂ nanoparticles. The advanced anode material exhibits a long-term capacity of 432.6 mA h g ^-1 at 5 A g ^-1 after 900 cycles and a rate capability of 419.6 mA h g ^-1 even at 10 A g ^-1 in the carbonate ester-based electrolyte. This avenue can be applicable for preparing other metal sulfide/carbon anode materials for sodium-ion batteries.
Competing Interests: There are no conflicts to declare.
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