The Preparation, Electrochemical Energy Storage Properties And Mechanism Study Of Titanium-based Anode Materials

Lithium ion batteries (LIBs) have attracted extensive attention because of the large energy density, high open-circuit voltage, low self-discharge rate, long lifespan and environmental benignity. However, there exists potential safty risk for the traditional carbon anode materials with low energy density. As a result, it is necessary to exploit an ideal candidate to subsititute the traditional materials for LIBs. TiO2as an ideal material for photocatalysis, is also widely used as an high performance anode material for LIBs. The formation of lithium dendrites can be avoided because of the higher voltage plateau for TiO2, which has superior security to carbon materials. In addition, the abundant storage and stable electrochemical properties for TiO2makes it possible for large-scale production. In order to overcome the shortages of TiO2, three ways have been used to improve its performance. The details are as follow:1. We have fabricated TiO2mesoporous microspheres with nanorod structure by means of hydrothermal reaction. Carbon coated TiO2(C-TiO2) can be also prepared by mixing with citric acid through the calcination in N2atmosphere. Through this way, the electric conductivity can be significantly improved for C-TiO2. What’s more, the structure distortion can be prevented with the carbon coated on the surface and within the mesoporous structure, which guarantees the excellent cycling performance and rate capability. C-TiO2shows superior electrochemical performance to commercial anatase TiO2with size around25nm.2. We have successfully fabricated pure Li4TisO12and Li4Ti5O12/rutile TiO2composites using different malor ratios of Li/Ti with above mentioned mesoporous TiO2as precursor. Li4Ti5O12is considered as the most promising anode materials because of the electrochemical stability, wide voltage plateau and the negligible volum expansion. In order to improve the specific capacity and lithium ion diffusion coefficents for Li4Ti5O12, we fabricated Li4i5O12/rutile TiO2nanocomposites, in which rutile TiO2possesses higher theoretical capacity (335mAh/g). The electrochemical test result shows that4-5-LTO-RT electrode possesses the most competitive electrochemical performance.3. Because of the stable electrochemical properties for TiO2, we deposited Fe2O3nanorods on TiO2nanosheets by hydrothermal method to improve its capacity. As all we know, Fe2O3is also considered as an ideal anode material as a result of the high theoretical capacity, low cost and environmental benignity, however, the large volume expansion in the charge-discharge process for Fe2O3is still the primary problem to overcome. Therefore, we fabricated TiO2@Fe2O3nanocompsite arrays. By this way, the electrochemical stability of TiO2and the high specific capacity of Fe2O3can be combined together, which makes TiO2@Fe2O3electrode possesses excellent electrochemical performance through "synergetic effect".