Synthesis of lithium insertion material Li4Ti5O12 from rutile TiO2 via surface activation

The synthesis of spinel-type lithium titanate, Li4Ti5O12, a promising anode material of secondary lithium-ion battery, from “inert” rutile TiO2, is investigated. On the purpose of increasing the reactivity of rutile TiO2, it is treated by concentrated HNO3. By applying such activated rutile TiO2 as the titanium source in combination with the cellulose-assisted combustion synthesis, phase-pure Li4Ti5O12 is successfully synthesized at 800 °C, at least 150 °C lower than that based on solid-state reaction. The resulted oxide shows a reversible discharge capacity of ∼175 mAh g−1 at 1 C rate, near the theoretical value. The resulted oxide also shows promising high rate performance with a discharge capacity of ∼100 mAh g−1 at 10 C rate and high cycling stability.