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/H₂ 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 H₂ 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.