Research On Fabrication And Electrochemical Performance Of Lithium Titanate Applying Hydrothermal Method

Spinel lithium titanate(Li4TisO12)as anode material for lithium ion battery has an extremely long and stable potential platform(1.5-1.6 V vs.Li/Li+),which can adequately avert the formation of SEI film and lithium dendritic crystal.In addition,spinel Li4TisO12 is a zero-strain material,it does not undergo significant volumetric change during the charge/discharge process,thus insuring excellent cycling stability and long cycling lifetime.These two characteristics make it as a potential candidate anode material for the next generation Lithium ion batteries.However,the low electrical conductivity(10-13 S/cm)of Li4Ti5O12 seriously limits practical applications at high rate capability.To overcome the weakness,two common and effective strategies are adopted.One is design of special morphologies of Li4Ti5O12.The other specifically effective strategy is to fabricate Li4Ti5O12/C composite materials.In this paper,flake Li4TisO12 was synthesized by a hydrothermal method and the effects of the proportion of raw materials(Li:Ti mole ratio)and calcination temperature on the electrochemical property of Li4TisO12 were investigated.The results displayed that when Li:Ti=5.5:5 and the calcination temperature was 700?,the electrochemical property of the fabricated Li4Ti5O12 sample is optimum.At 0.1 C,the initial discharge capacity of Li4Ti5O12 electrode was 186.3 mAh/g and still maintained 147.6 mAh/g after 100 cycles.Furthermore,the discharge capacity of Li4Ti5O12 electrode reached up to 102.8 mAh/g after 500 cycles at a rate of 10 C.In order to enhance the electrical conductivity of Li4Ti5O12,the Li4Ti5O12/C nanocomposite was fabricated via a hydrothermal method following by annealing treatment at 700? for 6 h using CTAB as a carbon source.Research showed that the Li4Ti5O12/C nanocomposite exhibited excellent electrochemical performance when the carbon content was 2.88%.The initial discharge capacity of Li4Ti5O12/C electrode was 190.6 mAh/g at 0.5 C,a stable capacity of 160.6 mAh/g was still kept for Li4Ti5O12/C electrode after 100 cycles.The initial discharge capacity of Li4Ti5O12/C electrode was 111.2 mAh/g at 20 C,even after 1000 cycles,the discharge capacity remained at 106.5 mAh/g,corresponding to a capacity retention rate was up to 95.8%with only 0.004%capacity loss per cycle.The coulombic efficiency maintained almost constant at approximately 100%.To further achieve the application of Li4Ti5O12 in the market,the Li4Ti5O12/GCP composite was prepared by a hydrothermal method and subsequent calcination at 700?applying graphite composite powder(GCP)as a conductive additive and carbon source.Research indicated that the initial discharge capacity of Li4Ti5O12/GCP electrode was 171.3 mAh/g at 0.5 C,after 100 cycles,a capacity of over 150.6 mAh/g can be kept for Li4Ti5O12/GCP electrode.Even at a rate of 10 C,the discharge capacity of Li4Ti5O12/GCP electrode can reach up to 118.9 mAh/g and the coulombic efficiency maintained almost constant at approximately 100%.