Nanoengineering to achieve high sodium storage: a case study of carbon coated hierarchical nanoporous TiO₂ microfibers

Nanoengineering of electrode materials can directly facilitate sodium ion accessibility and transport, thus enhancing electrochemical performance in sodium ion batteries. Here, highly sodium-accessible carbon coated nanoporous TiO₂microfibers have been synthesised via the facile electrospinning technique which can deliver an enhanced capacity of ≈167 mAh g⁻¹after 450 cycles at current density of 50 mA g⁻¹and retain a capacity of ≈71 mAh g⁻¹at the high current rate of 1 A g⁻¹. With the benefits of their porous structure, thin TiO₂inner walls, and the introduction of conductive carbon, the nanoporous TiO₂/C microfibers exhibit high ion accessibility, fast Na ion transport, and fast electron transport, thereby leading to the excellent Na-storage properties presented here. Nanostructuring is proven to be a fruitful strategy that can alleviate the reliance on materials' intrinsic nature; and the electrospinning technique is versatile and cost-effective for the fabrication of such an effective nanoporous microfiber structure.