Preparation And Electrochemical Performance Study Of TiO₂ Using As The Anode Materials For Lithium Battery

As the anode materials in the lithium battery,the improved safety of TiO₂ comes from its higher working potential compared with the lithium metal,efficiently avoiding the formation of lithium metal dendrites.Besides,the low volume variation?<4??during the charge-discharge process also accounts for the good structure stability and prolonged cycling life.However,the intrinsic poor electronic conductivity has prevented TiO₂ from enhancing practical lithium storage properties.To improve its conductivity,three ways have been tried,including structure controlling,particle size reduction and carbon introduction.The TiO₂ was successfully prepared by the electrostatic spinning method.Influence of heat-treating temperature and dwelling time on its electrochemical performance was studied.The phase structure and the morphology of the samples were characterized by the X-ray diffraction?XRD?and the scanning electron microscopy?SEM?,respectively.Pure anatase TiO₂ with one-dimenstional structure heated at 450? with a dwelling time of 1,2 and 3h was obtained.It was found that the TiO₂ sample heated at 450? for 2h exhibited an optimum electrochemical performance among the three samples.For the first cycle,the discharge capacity of the sample reached 203.2,177.2,153.4 and 131.6mAh/g at different rates of 0.2C,0.5C,1C,2C,respectively.After 100 cycles,it could retain 89?of its initial discharge capacity at 0.2C rate.Moreover,its resistance was lower and the lithium-ion diffusion coefficient was higher than that of the other two samples.Anatase TiO₂ was prepared by the hydro-thermal method.The influence of the dispersing agent on the particle size and the electrochemical performance for TiO₂ was studied.It was found that the particle coarsing and agglomeration could be inhibited by the addition of PAA or HCl.Therefore,the electrochemical performance was improved compared with that of the sample without the dispersing agent.Moreover,the resistance decreasing and the Li+ diffusion coefficient increasing could be realized as a result of the dispersing agent addition.For the two dispersing agent,the effect of the PAA was better than that of HCl.On the basis of the DSC?differential scanning calorimeter?and XRD data,it was found that the synthesizing temperature for the anatase and rutile TiO₂ increased with the introduction of the carbon.The amorphous carbon existed in the composite.Therefore,the electronic conductivity for the composite was improved,which led to the improvement of the electrochemical performances for TiO₂/C composite prepared by the electrostatic spinning or the hydro-thermal method.