Multiwalled carbon nanotubes–V2O5 integrated composite with nanosized architecture as a cathode material for high performance lithium ion batteries

Abstract

Multiwalled carbon nanotubes (MWCNTs)–V₂O₅ integrated composite with nanosized architecture has been synthesized through hydrothermal treatment combined with a post-sintering process. During the hydrothermal reaction, protonated hexadecylamine (C₁₆H₃₃NH₃⁺) acts as an intermediator, which links the negatively charged vanadium oxide layer with the mixed-acid pretreated MWCNTs by weak electrostatic forces to form a three-phase hybrid (MWCNTs–C₁₆–VO_x). MWCNT–V₂O₅ composite and V₂O₅ nanoparticles can be obtained by sintering MWCNTs–C₁₆–VO_x at 400 and 550 °C in air, respectively. Among them, MWCNTs–V₂O₅ possesses better electrochemical performance as a cathode material for lithium ion batteries (LIBs). The unique porous nanoarchitecture of MWCNTs–V₂O₅ provides a large specific surface area and a good conductive network, which facilitates fast lithium ion diffusion and electron transfer. Additionally, the uniformly dispersed MWCNTs conducting network also behaves as an effective buffer which can relax the strain generated during charge–discharge cycles. Electrochemical tests reveal that MWCNTs–V₂O₅ could deliver a superior specific capacity (402 mA h g⁻¹ during initial discharge at a current density of 100 mA g⁻¹ between 1.5 and 4 V versus Li/Li⁺), good cycling stability (222 mA h g⁻¹ after 50 cycles) and high rate capability (194 mA h g⁻¹ at a current density of 800 mA g⁻¹).