Phosphorus-Modulation-Triggered Surface Disorder in Titanium Dioxide Nanocrystals Enables Exceptional Sodium-Storage Performance.

Structural modulation and surface engineering have remarkable advantages for fast and efficient charge storage. Herein, we present a phosphorus modulation strategy which simultaneously realizes surface structural disorder with interior atomic-level P-doping to boost the Na+ storage kinetics of TiO2 . It is found that the P-modulated TiO2 nanocrystals exhibit a favourable electronic structure, and enhanced structural stability, Na+ transfer kinetics, as well as surface electrochemical reactivity, resulting in a genuine zero-strain characteristic with only approximately 0.1 % volume variation during Na+ insertion/extraction, and exceptional Na+ storage performance including an ultrahigh rate capability of 210 mAh g-1 at 50 C and a strong long-term cycling stability without significant capacity decay up to 5000 cycles at 30 C.