Research On Li₄Ti₅O₁₂ As The Negative Materials For Lithium Ion Batteries

Spinel Li₄Ti₅O₁₂is promising anode material for rechargeable lithium ion batteriesdue to its “zero-strain”. Its high reversible capacity is175mAh/g, and has a dischargeplatform of1.55V relative to lithium metal. But the low ionic and electronicconductivity （10-9S/cm） restricts its application. Li₄Ti₅O₁₂was prepared by hightemperature solid state reaction in this paper. The structure and particle size distributionof the sample were investigated by XRD, laser particle size analyzer. Meanwhile,electrochemical properties were analyzed through CV and charge-discharge test.The preparation of Li₄Ti₅O₁₂by solid state method was optimized. The resultsshowed that Li₄Ti₅O₁₂synthesized with rutileTiO2and Li2CO3at800℃,12h, ballmilling had stable platform voltage and high discharge specific capacity.Lithium titanate was doped with a large proportion of metal（Al、Mg、Cr、Mn）,all of the doped sample showed bad capacity. The platform voltage of the sample dopedwith metal （Al、Mg、Cr） didn’t change. The results indicated that the platform voltage ofthe sample doped with Mn was changed.In order to improve its electronic conductivity, Li₄Ti₅O₁₂was prepared with ureaas nitrogen source. The results showed that the sample still was the spinel structure, Thefirst discharge specific capacity of sample increased than pristine Li₄Ti₅O₁₂, the sampleLi₄Ti₅O₁₂also had better cycling behavior.The Li₄Ti₅O₁₂was modified by carbon with lucose as carbon source, The resultsindicated that the suitable amount of glucose was20%. The electronic conductivity ofLi₄Ti₅O₁₂coated with C was improved obviously. The initial discharge specific capacityof the Li₄Ti₅O₁₂was167.06mAh/g at the rate of0.2C. The Li₄Ti₅O₁₂/C also displayedthe good electrical performance at1C.