Emcoating Architecture Construction via CO2/H2 Coupling Treatment Doubles Reversible Capacity of NbO2/C Anode

As a promising alternative as lithium-ion anode, niobium dioxide appeals to researchers due to high theoretical capacity and good electron conductivity. However, rarely work about NbO2 based high performance anode is reported. Here, NbO2 nanoparticles emcoated in continuous carbon matrix is constructed through CO2/H-2 coupling treatment. CO2 activation introduces unique carbon emcoating structure, which builds interconnected electron conductive network with low carbon content. Furthermore, crystallographic phase of NbO2 is enhanced during H-2 treatment, which increases the lithium storage ability. Electrochemical performance of NbO2 anodes is significantly improved based on the carbon emcoating structure. A high reversible capacity of 391 mAh g(-1) is retained after 350 cycles at 0.2 C. Additionally, at a current density of 1 A g(-1), the reversible capacity reaches 139 mAh g(-1). Compared with conventional NbO2/C nanohybrids, the lithium diffusion coefficient of carbon-emcoated sample shows improvement of three orders of magnitude. Moreover, the in situ XRD investigation shows a reversible lithium insertion behaviour with a limited volume change.

Automated summary

In this study, niobium dioxide nanoparticles coated in a continuous carbon matrix were constructed through CO2/H-2 coupling treatment. The resulting carbon-emcoated NbO2 sample exhibited improved electrochemical performance and a high reversible capacity of 391 mAh g(-1) after 350 cycles at 0.2 C.