Research On Li₄Ti₅O₁₂ As Anode Material For Lithium-ion Batteries

In this paper,a series of lithium titanate cathode materials were prepared though solid-state reaction process from the angle of the commercialization to improve their rate performance by modification.X-ray diffraction（XRD）analysis and scanning electron microscopy（SEM）techniques were employed to study their structures and morphologies.Thecharge-dischargecycling,electrochemicalimpedance spectroscopy（EIS）analysis and cyclic voltammetry（CV）tests were performed to study their electrochemical performance.The optimal synthesis of lithium titanate materialsthough solid-state reaction process as follows:Excess lithium carbonate（8 wt%）was provided to compensate for lithium evaporation and wet mixing mode was used before the final calcination at 850?C for 12 h.The experimental results showed thatthe pure spinel lithium titanate prepared by this optimal synthesispresented the best electrochemical performance anddelivered the first discharge capacities of 152.3（0.2C）,111.2（1C）,93.4（2C）,63.7（5C）and 35.6（10C）mAhg^-1,respectively.The effects of organic susbstanceassisted combustion（polyethyleneglycol,citric acid,sucrose）,Al³⁺doping（Al（OH）₃）,Mg²⁺doping（Mg₂（OH）₂CO₃）,Cr³⁺doping（Cr₂O₃）on the electrochemical properties of Li₄Ti₅O₁₂ were systematically investigated.The experimental results showed that theLi_3.5Mg_0.5Ti₅O₁₂ material doped by Mg²⁺exhibited the best electrochemical performance.It delivered the first discharge capacities of 168.72（0.2C）,133.24（1C）,119.18（2C）,100.42（5C）and79.85（10C）mAhg^-1,respectively,and a reversible capacity of 96.62 mAh.g^-1 with about 96.22%capacity retention after 500 cycles at 5C discharge rate was achieved.