Preparation Of Lithium Titanate Anode Materials For Lithium Ion Battery And Their Electrochemical Property

Lithium-ion batteries (LIBs) are considered to be the best performance of the batterysystem, due to their high voltage, small size, light weight, environmental pollution, long lifecycle and high specific capacity, and have attracted much attention by worldwidecompanies and researchers. As an important part of LIBs, the anode materials can greatlyaffect the whole performance of the LIBs. Recently, lithium titanate is seen as a promisingnegative material in LIBs due to its stable platform for charging and discharging, the "zerostrain" of the electrode material, good cycling performance, and the faster charge anddischarge rate and other advantages over carbon anode materials. Meanwhile, nanosizedmaterials for anodes have showed excellent performance and their preparation andelectrochemical performance studies have attracted wide attention from researchers.In this thesis, lithium titanate-based composites were prepared. Their structures werecharacterized by XRD, SEM, TEM, and other techniques. Their lithium storageperformance was evaluated and their electrochemical performance was tested in details.The following is our main work:(1) Ti3+-Li4Ti5O12-TiO2composites were prepared by hydrothermal-pyrolysisroute.Ti3+-Li4Ti5O12-TiO2composites were prepared using titanium powder as the sourcematerials, by hydrothermal-pyrolysis method followed by subsequent annealing treatmentin a reduction atmosphere. This route features effective, environmentally friendly and lowcost. Through a series of comparative tests, the cycle performance of Ti3+-Li4Ti5O12-TiO2nanocomposites was significantly improved, and under the high current density, thecomposites showed higher capacity and rate capability.(2) Li4Ti5O12/R-TiO2composites were prepared by hydrothermal-pyrolysis route.Li4Ti5O12/R-TiO2composites were synthesized using titanium powder, sodiumhydroxide, lithium hydroxide as the source materials by hydrothermal-pyrolysis method.Studies have shown that, Li4Ti5O12/R-TiO2treated in ammonia has better electrochemicalproperties. (3) Nitrogen-doped carbon coated lithium titanate nanoparticles were prepared bysolvothermal-pyrolysis route.Nitrogen-doped carbon coated lithium titanate nanoparticles were synthesized, usingtitanium tetrachloride as the source materials. Compared to the carbon coated lithiumtitanate and lithium titanate, nitrogen-doped carbon coated lithium titanate has goodelectrochemistry performance. The first discharge capacity is194mAh g-1with the rate of0.5C and the capacity was stable in the following cycles.