A high performance TiO2 anode modified by germanium and oxygen vacancies for lithium-ion batteries

A TiO ₂ anode modified by germanium and oxygen vacancies was fabricated using a hydrothermal method with an autoclave at 180 °C, followed by reduction sintering at 600 °C for 5 h in a reducing atmosphere. Germanium was obtained and distributed uniformly on the surface of the anatase TiO ₂ particles. Oxygen vacancies were identified on the TiO ₂ surface by electron paramagnetic resonance and X-ray photoelectron spectroscopy. The specific capacity of the Ge@TiO _2−x anode was 510 mAh g ⁻¹ after 550 charge-discharge cycles. The charge transfer and electrolyte impedance of Ge@TiO _2−x were smaller than those of the initial TiO ₂ . The lithium-ion diffusion coefficient in Ge@TiO _2−x was 7.87 × 10 ⁻¹³ cm ²·s ⁻¹, which was significantly higher than that of a commercial TiO ₂ anode. The germanium and oxygen vacancies in TiO ₂ provided more active sites for the transport of lithium ions and electrons, thereby reducing the energy barrier, accelerating the charge transfer of lithium ions and enhancing the conductivity and capacity of the Ge@TiO _2−x anode.