Research On Preparation And Modification Of Li₄Ti₅O₁₂ As Anode Material For Lithium Ion Battery

As one of the most promising anode materials for lithium-ion batteries, spinel Li₄Ti₅O₁₂ has been widely studied recently. Researches showed that doping with aliovalent ions can improve the electrochemical properties of electrode materials Li₄Ti₅O₁₂. This work concentrates on the influence of different doping elements on its electrochemical performance. This thesis mainly includes three aspects:?1? The Mg doped nanostructured Li₄Ti₅O₁₂ of spinel phase was synthesized by hydrothermal method and solid state reaction method with Li₂CO₃, TiO₂?P25? and Mg O as raw materials. The amount of Mg doping greatly affects the electrochemical performance of the products.The amount of Mg doping is 0.05, and the electrochemical performance of samples is best. The initial discharge capacity and charge capacity were 190.8 m Ahg^-1 and 195.2 m Ahg^-1 at 1C, and the discharge capacity also can reach 178.4 m Ahg^-1 after 100 times. Even at high current densities, the electrochemical performance is very excellent.?2? The Cr and Sb co-doped nanostructured Li₄Ti₅O₁₂ of spinel phase was synthesized by hydrothermal method and solid state reaction method with Li₂CO₃, TiO₂?P25?, Cr₂O₃ and Sb₂O₅ as raw materials. The amount of Cr and Sb co-doping greatly affects the electrochemical performance of the products. The amount of Cr and Sb co-doping is0.05, and the electrochemical performance of samples is best. The first discharge capacity and recharge capacity were 186.2 m Ahg^-1 and 151.7m Ahg^-1 at 1C, and the discharge capacity can still reach 171.32 m Ahg^-1after 100 times. Even at high current densities, the electrochemical performance is very good.?3? The Sb doped TiO₂ hollow spheres were synthesized by hydrothermal method. For the formation of Sb doped Li₄Ti₅O₁₂ hollow spheres, the above Sb doped TiO₂ hollow spheres in ethanol were further mixed with Li₂CO₃ according to the stoichiometric quantities of Li₄Ti_4.75Sb_0.25O₁₂. Afterwards, the mixture fully dried in air at 60 °C,and annealed at 800 °C for 8 h to obtain Sb doped mesoporous Li₄Ti₅O₁₂ hollow spheres?Sb-LTO?. The first discharge capacity and recharge capacity were 165.9 and 156.3 m Ahg^-1 at 1C rate, and the coulomb efficiency is as high as 94% for the first time. Moreover, the discharge capacity reached 154.4 m Ahg^-1 after 100 times, and the electrochemical performance is good at high current densities.