Porous structure O-rich carbon nanotubes as anode material for sodium-ion batteries

Carbon materials with high electronic conductivity and high surface area show obvious advantage as anode material for commercial sodium-ion batteries. Here, carbon nanotubes (CNTs) with porous and disordered structures (PCNTs) are synthesized via a facile K₂CO₃-assisted activation method. The open porous structures (specific surface areas of 444 m² g⁻¹) and abundant defects (O defects content of 7.2 at%) may not only shorten the transport path of Na ion, increase contact interface between electrolyte and electrode, but also facilitate the reversible capacity of Na storage. In addition, the 3D CNT conductive network improves the electronic conductivity. PCNT anode displays a favorable reversible capacity of 255 mAh g⁻¹ after 200 cycles at 0.1 A g⁻¹, with an initial Coulombic efficiency of 60% and excellent rate capability of 187 mAh g⁻¹ at 2.00 A g⁻¹. This work gives a simple strategy for manufacturing porous CNT anode for advanced energy storage devices.