Preparation And Electrochemical Performance Of Doped Li₄Ti₅O₁₂ As Anode Materials For Lithium-ion Batteries

Recent years, spinel Li4Ti5O12has attracted significant attention as a promisingcandidate of cathode materials for lithium-ion batteries due to its superior cyclingstability, outstanding safety performance, low cost and environmentally friendly.However, low electronic conductivity and poor high-rate performance are the mainobstacles for the development and commercialization of Li4Ti5O12. In order toimprove the conductivity, rear earth ions doping and metal nanocrystals combinationwere mainly used to improve the electrochemical performance of Li4Ti5O12.Li4Ti5O12nanocrystals were synthesised by the method of hydrothermal methodand subsequent annealling process, using tetrabutyl titanate as titanium precursor,lithium hydroxide monohydrate as Li precursor and RE3+(RE=Gd3+, Y3+, La3+) ionsas doped ions. The XRD, Raman, SEM, EDS, TEM results of the saamples withdifferent norminal doping concentrations （0%、6%、10%） show that theas-synthesized nanocrystals are spinel Li4Ti5O12, and with the increase of RE3+doping concentration, the thick nanosheets with irregular shape are converted toregular ultrathin nanosheets with a thickness of~8.5nm, meanwhile the surface areaincrease from32.9to43.4m2g-1. The electrochemical properties of samples withdifferent RE3+doping concentration through the charge and discharge performancetest, cyclic voltammetry and EIS are measurd, indicating that the Li4Ti5O12naosheetsdoped with RE3+show better electrochemical performance. For example, when thedoping concentration of Gd3+increase to10%, the ultrathin nanosheets with nominaldoping concentration of10%show the initial discharge capacity of175.88mAh/g atthe current rate of1C, capacity kept at164.83mAh/g after100cycles, and highdischarge specific capacity retention rate as high as93.7%. In order to further improve the electrochemical performance of Li4Ti5O12materials, the Li4Ti5O12/Ag composite materials was prepared via a simple electrolessdeposition (ED) method, using Gd3+doped Li4Ti5O12ultrathin nanosheets as supporter.The measured electrochemical performance indicates that the cyclability and ratecapability of Li4Ti5O12/Ag composites are excellent. High reversible dischargespecific capacity of188.38、174.63、164.59、154.44、148.69mAh/g at1C,5C,10C,20C and30C rate are demonstrated, respectively, and when back to1C, it stillshows a high discharge specific capacity of184.37mAh/g.