Preparation And Properties Of Li₄Ti₅O₁₂ As Anode Material Of Lithium-Ion Batteries

In this paper, Lithium Titannate was synthesized by sol-gel method and solid-state reaction respectively. In addition, Thermogravimetry-Differential Thermoanalysia(TG-DTA) was used to fix the sinter temperature, X-Ray Diffraction(XRD) to analyze micro-structure, Scanning Electron Microscope(SEM) to observe superficial morphology. Galvanostatic charge-discharge test, Cycle Voltammagram(CV) and Electrochemical Impedanc Spectroscopy(EIS) were used to study specific capacity and cyclic behavior.Anode material Li₄Ti₅O₁₂ for lithium ion batteries had been prepared by a sol-gel method with Tetra-n-butyl Titanate and Li₂CO₃ as starting materials and citric acid as a chelating agent. Citric acid can complex with Ti and Li at the same time to realize more uniform distribution of ions and smaller particle size in the solution. The effect of amount of chelating agent on electochemical properties of product was investigated. In our study, the sample synthesized at 650℃for 8h and 850℃for 16h with citric acid to titanium molar ratio R = 1∶2 showed the best discharge capacity of 148.65mAh/g and 116.82mAh/g for the first cycle and the 100th cycle respectively. The capacity retention was 78.59%。Anode material Li₄Ti₅O₁₂ using LiAc as Li source had smaller paricle distance and contacted each other closer. The material had better electochemical properties than the former using Li₂CO₃. It had a first discharge capacity of 153.61mAh/g and obtained 143mAh/g with a capacity retention of 80.96% after 100 cycles.Li₄Ti₅O₁₂ materials synthesized by solid-state reaction were prepared with amorphism TiO2 and Li₂CO₃ as the raw materials. The results demonstrated that the materials of best performance were sintered by two-step method, the raw materials were pre-sintered at 650℃for 8h then were treated at 850℃for 16h. The Li₄Ti₅O₁₂ as the anode materials for lithium ion battery had a first discharge capacity of 159.16mAh/g, and a long platform around the voltage of 1.55V. The sample obtained a capacity of 143mAh/g with a capacity retention of 89.9% after 100 cycles. The materials showed fine cycling properties.The carbon modification using dextrose as carbon source was researched. The results showed that 20%wt was the best carbon doping quantity, the materials had a first discharge of 172.94 mAh·g-1. The sample with 10%wt carbon had a little improvement in cyclic stability and diacharge capacity. However, the 30%wt carbon doped sample's electrochemical properties were weakened.