Synthesis And Electrochemical Properties Of Li₄Ti₅O₁₂ And Its Composites Anode Material For Lithium Ion Batteries

As energy and the enviroment crisis obtain more attention as a result of economic development, new energy has become a research focus. To utilize new energy, one of the critical steps is its storage and conversion, and for this step, Lithium-ion battery is always considered to be an ideal choice and receives more and more attention. Develeping excellent battery material underlies high power lithium-ion with long lifed and less enviroment pollution.The anode materials of Li4Ti5O12as the "zero-strain" materials:they neither react with electrolyte, for their high discharge plateau (about1.55v), which guarantees the safety of lithium-ion battery, nor change their structure during charging and discharging, for their stable structure. For all these features, Li4Ti5O12has attracted many reseachers. However, its poor electron conductivity doesn’t support a better rate performance. In this essay, Li4Ti5O12and Cu/Li4Ti5O12are prepared successfully based on the preparation and modification of Li4Ti5O12. The main contents are as follows:1. Detailing the research status of anode materials of lithium-ion battery and Li4Ti5O12, and clarifying the significance and problems to be resolved of Li4Ti5O12researching.2. The precursor Li1.81H0.19Ti2O5·xH2O nanosheet has been synthesised by hydro-thermal method without any template and surfactant, usinng TBT as Ti-source and LiOH·H2O as Li-source. Based on the research of how the length of reacting time influences the appearance of the precursor, finding out the optimal condition for the precursor by controlling the time length. In the observation of the reaction of the precursor, the grow mechanism of Li1.81H0.19Ti2O5·xH2O is concluded. Then calcinate the precursor in certain temperature, and the temperature and the phase of the precursor transformed into Li4i5Oi2were studied by TGAand XRD. The sample calcined at500℃has the best electrochemical performance. Therefore, we can safely achieve that the growing of the precursor have impact on the growing of Li4Ti5O12in hydro thermal system, and the Li4Ti5O12nanosheet compounded in hydrothermal system is a kind of potential Lithium-ion anode materials for its good performance in electrochemical property.3. The micro/nanoscale hybrid Li4Ti5O12and Cu/Li4Ti5O12composites are obtained at hydrothermal temperature as low as180℃and subsequent calcination treatment in5%H2containing Argon (Ar) atmosphere at600℃for3h. The obtained micro-/nanoscale Cu/Li4Ti5O12composites with different contents of metallic Cu were determined by ICP, the Cu content is0wt.%,3.75wt.%,7.5wt.%,15wt.%,22.5wt.%, respectively. the Cu metal is dispersed in the matrix of Li4Ti5O12,and the presence of Cu has no effect on the crystal structure of spinel Li4Ti5O12. The key strategy in this work is to investigate the influence of the Cu content on the electrochemical properties of Li4Ti5O12. The Cu/Li4Ti5O12(15wt.%) composite performs the best electrochemical performance, with the capacity of107mAh/g after1000cycles, in the potential range of1.0-3.0V (Li+/Li) at current densities of20C.4. To evaluate the performance of laboratory-compounded Li4Ti5O12when it is used as total battery, the Li4Ti5O12is combined with the LiNi0.5Mn1.5O4(4.8V) compounded by others. To explore the commercial application feasibility of laboratory material.