Coaxial Carbon Nanotube Supported TiO₂@MoO₂@Carbon Core–Shell Anode for Ultrafast and High-Capacity Sodium Ion Storage

Abstract

The sluggish kinetic in electrode materials is one of the critical challenges in achieving high-power sodium ion storage. We report a coaxial core-shell nanostructure composed of carbon nanotube (CNT) as the core and TiO₂@MoO₂@C as shells for a hierarchically nanoarchitectured anode for improved electrode kinetics. The 1D tubular nanostructure can effectively reduce ion diffusion path, increase electrical conductivity, accommodate the stress due to volume change upon cycling, and provide additional interfacial active sites for enhanced charge storage and transport properties. Significantly, a synergistic effect between TiO₂ and MoO₂ nanostructures is investigated through ex situ solid-state nuclear magnetic resonance. The electrode exhibits a good rate capability (150 mAh g^-1 at 20 A g^-1) and superior cycling stability with a reversibly capacity of 175 mAh g^-1 at 10 A g^-1 for over 8000 cycles.