Building a PEG-C@MoSe2@CNT heterostructure via in-situ selenidation as highly reversible anodes for Na+ batteries

Herein, we describe a simple and efficient method to build C@MoSe 2 @CNT composites that exhibit good electrochemical performance as anode materials for sodium-ion batteries. The protocol uses commercially available and cheap carbon nanotubes (CNT) as the conductive network. Molybdenum selenide (MoSe 2 ), in-situ -synthesized from Mo-ethylene glycol (poly(ethylene glycol) (PEG, M n ≈ 200)) complexes, grows along the CNT with a discontinuous morphology, which creates multiple channels for the insertion of Na + . Meanwhile, PEG-C provides a thin carbon coating layer to increase stability. For PEG-200-2-C/MoSe 2 /CNT at room temperature, the storage at 2 A g −1 is 426 mA h g −1 after 500 cycles and 212 mA h g −1 after 3,000 cycles. Compared with pure MoSe 2 , density functional theory calculations indicate that the Na + diffusion barrier in the MoSe 2 of C@MoSe 2 @CNT effectively decreases from 0.91 to 0.72 eV, hence promoting the reversibility of the Na + storage.