Boosting Pseudo‐capacitive Sodium Storage in Ultrafine Titanium Dioxide by an In‐situ Porous Forming Strategy

Abstract Due to its properties (stable, affordable and non‐toxic), titanium dioxide (TiO₂) has a promising future as electrode material for sodium‐ion batteries (SIBs). Its Na⁺ insertion/deinsertion mechanism, on the other hand, results in poor electronic conductivity and sluggish ionic diffusivity, leading to rapid capacity fading. Herein, a molten salt method is employed to creat abundant carbon pores framework, being capable of supporting plentiful ultra‐fine TiO₂ adhering (U‐TiO₂/C). With this unique porous structure of lots of exposed active sites, the U‐TiO₂/C composite provides a faster ions transport and volume expansion buffer zone during cycling. As anode for SIBs, the U‐TiO₂/C manifests splendid electrochemical performance. Specifically, the U‐TiO₂/C electrode delivers a high capacity of 202.7 mAh g⁻¹ after 100 cycles at 0.1 A g⁻¹ and 91.4 mAh g⁻¹ at 1.0 A g⁻¹ after 160 cycles. Even with the increased current density to 10.0 A g⁻¹, the U‐TiO₂/C electrode still performs a high capacity of 69.5 mAh g⁻¹ after 2500 cycles. Detailed kinetic analysis has been investigated to quantificationally demonstrate that the surface pseudocapacitive storage behavior plays a dominant role in the enhanced sodium storage.