The reasonable insertion potential of sodium and the abundant resources of titanium make the TiO2 a promising anode material for sodium-ion batteries (SIBs). However, semi-conductivity type of pristine TiO2 with sluggish redox kinetics has retarded its practical application. In this work, we designed a simple method to in-situ form oxygen vacancies (Vo) in flexible TiO2 (F-TiO2-x) anode for SIBs by ex situ electrospinning. Thanks to the existence of Vo, the F-TiO2-x flexible anode can deliver an ultrahigh reversible capacity of 353 mAh g-1 at 0.1C. Even at relatively high rate of 1C, a charge capacity of 331 mAh g-1 can be still maintained after 1000 cycles. Moreover, the function mechanism of Vo is illustrated by first-principles density functional theory (DFT) methods, which demonstrates that the Vo can change the electronic structure and enhance the electronic conductivity. Meanwhile, cross-linked conductive network of carbon nanofibers can further facilitate the ions/electrons transmission. Furthermore, such a simple but effective ex situ electrospinning method to prepare flexible electrode contained in-situ formed Vo is expected to be widely accepted by various systems other than SIBs.

In-situ formed oxygen vacancies in flexible anatase TiO2 anode to induce ultrahigh sodium storage capacity for sodium ion batteries

ACS Spring Meeting 2021

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