90 C fast-charge Na-ion batteries for pseudocapacitive faceted TiO2 anodes based on robust interface chemistry

Sodium-ion batteries are a potential candidate for next-generation energy storage devices. Unfortunately, developing an anode with improved long-term cycling stability and high-rate performance remains a substantial problem. In this work, we develop that the Na+ intercalation pseudocapacitance in faceted titanium dioxide endows extreme fast charging and long cycle life in a sodium-ion battery. Theoretical calculations and comprehensive characterization exhibit that high ionic conductivity, stable solid electrolyte interphase (SEI), and pseudocapacitive behavior are essential for fast charging. This well-designed electrode demonstrates a significantly high reversible capacity of about 135 mAh g−1 at 90 C (∼30 A g−1) for 10,000 cycles with an 87.8% retension. Coupled with a vanadium phosphate sodium Na3V2(PO4)3 cathode, and this full cell displays a specific capacity of 310 mAh g−1 at 0.2 A g−1 for 100 cycles. This study unveils the key mechanisms for fast-charging sodium storage, and can also facilitate the improvement of other titanium-based anodes secondary batteries.