In-situ synthesized binder-free flocculent TiO2-x film as anode for lithium-ion batteries

Herein, a novel in-situ approach is exploited to fabricate flocculent TiO2-x film on the Ti foil surface by efficient micro-arc oxidation (MAO) and hydrothermal reaction, which is used as a binder-free anode directly for lithium-ion batteries (LIBs). After introducing oxygen vacancies through hydrothermal reaction, many nano-particles grow on the surface of framework and form 3D flocculent structure. The electrochemical impedance of the as-prepared TiO2-x anode decreases one order of magnitude after hydrothermal treatment. As a result, this TiO2-x film delivers a high capacity of 844 mA h cm−3 (more than 200 mA h g−1) at current density of 10 μA cm−2, which is much higher than that of untreated TiO2 film (225 mA h cm−3). Furthermore, during the discharge-charge cycles, the nano-particles continue to shrink and homogenize without any cracks and dropping off on the surface because of its excellent stability. As a result, the conductivity of this TiO2-x film has a certain increament, which enhances the cyclic performance of the TiO2-x anode. These phenomena have great significance for its application in the field of LIBs.