Synthesis And Modification Of Nano Li₄Ti₅O₁₂Materials

As one of the anode materials for lithium-ion batteries,Li4Ti5O12(LTO)has many outstanding properties,such as zero strain effect,stable charge and discharge platform,good cycle stability etc.However,the low conductivity and specific capacity have restricted its large-scale application.In order to improve the electrochemical properties of Li4Ti5O12,this paper showed a facile preparation of nano Li4Ti5O12,and discussed the properties of Li4Ti5Oi1 physical doped with graphene.The materials were characterized by Thermogravimetry-differential thermoanalysis(TG-DTA),X-ray Diffraction(XRD),scan electron microscope(SEM),particle size analysis(PSA)and investigated by constant current charge-discharge test at room temperature.Firstly,this study disscussed the optimum condition for preparing nano Li4Ti5O12 via“microwave hydrothermal method”.At the same time,the influence of the synthesis conditions on the phase composition,morphology and charge-discharge performance of the LTO was also investigated,including the reactant ratio,microwave hydrothermal reaction time,calcination temperature,calcination time and emulsifier OP.These five factors were proved to have important effects on features of the LTO.And the optimal synthesis conditions are the lithium titanium ratio of 0.84,microwave hydrothermal reaction time of 20 min at 150 ?,the calcination temperature of 500 ? and calcined for 1 h,adding an appropriate amount of emulsifier OP.Under these conditions,we obtained nano Li4TisO12 with high purity and crystallinity.The particle is ball shaped and has smaller size(about 20 nm).Electrochemical experiments showed that the nano Li4Ti5O12 exhibited a high initial discharge capacity of 130.6 mAh/g at 0.1 C rate,and the capacity retention rate reached up to 92%after 20 cycles.Besides,it had a very stable discharge platform accounted for about 75.2%of the whole time.Then,this study discussed the properties of nano Li4Ti5O12 physical doped with graphene(doping amount of 1.5%).The result showed that the mixed material had a good electrochemical performance.The discharge platform was stable,and its initial discharge capacity was up to 140.1 mAh/g at 0.1 C rate.After twenty cycles,the capacity retention rate remained in 93.4%.They were both higher than the corresponding values of pure nano Li4Ti5O12.