Preparation and electrochemical properties of nanocable-like Nb₂O₅/surface-modified carbon nanotubes composites for anode materials in lithium ion batteries

Highlights: •The acid pretreatment for CNTs is a key factor to fabricate nanocable-like Nb₂O₅/SMCNTs composites. •The polar functional groups can induce the symmetrical growth of Nb₂O₅ nanoparticitles on the surface of SMCNTs. •SMCNTs can provide sufficient conductive contacts for composites and abundant active sites for electrochemical reaction. -- Abstract: Uniform nanocable-like Nb₂O₅/surface-modified carbon nanotubes (SMCNTs) composites for anode materials in lithium ion batteries were synthesized by hydrothermal method. It was indicated that Nb₂O₅ nanoparticles were tightly and uniformly cultivated on carbon nanotubes when CNTs were pretreated with concentrated H₂SO₄. As a result, Nb₂O₅/SMCNTs composite materials showed remarkable electrochemical performance as anode materials for lithium-ion batteries. It delivered a high reversible capacity of 441 mA h g⁻¹ cycled at the current density of 40 mA g⁻¹ after 100 cycles and an excellent rate capacity of 185 mA h g⁻¹ at the high current density of 5000 mA g⁻¹ after 200 cycles.