| The spinel Li4Ti5O12is a zero strain material, with negligible structure change during Li+diffusion, which has been considered as one of the most prospective anode materials for Li-ion batteries because of its excellent safety performance, low manu-facturing cost and environmental friendly. However, the application of Li4Ti5O12an-ode material is limited, due to its ionic and electronic conductivity and poor phe-nomenon in charging/discharging under strong current resulted severe polarization. Therefore, to improve the rate performance of Li4Ti5O12materials by modification is the key to its commercialization.In the work, a kind of Li4Ti5O12material was prepared through solid-state reac-tion, using the anatase TiO2and LiCO3as raw materials. The microstructure and morphology of the samples were characterized by test such as TG-DSC, XRD, SEM, EDS and Raman. And the electrochemical performance of it was studied through testing of galvanostatic charge/discharge cycling, CV and EIS.Using the solid-state method, and combined with two-step sintering system, ef-fects of the time and temperature of the low and high termperatures sintering process on the electrochemical performance of the pure phase Li4Ti5O12were studied by or-thogonal experiments. The experimental results show that the pure spinel Li4Ti5O12prepared from the condition of first held at600℃for4h and then calcined at800℃for12h had the best rate performance. The as-prepared samples had cubic spinel crystal structure, which was compliance with standard LiTi5O12card, and exhibited a uniform particle size distribution. At charge/discharge rate of0.1C,1C and10C at room temperature, its original discharge capacities were163.9mAh/g,122.9mAh/g and80.4mAh/g, respectively. Over twenty cycles, the retention rate of capacity were97.0%,95.3%and86.3%.Combining the optimized synthetic conditions, the LiTi5O12materials were based on Ti doping Nb5+, Li doping Al3+modified research. The effect of doping with different content on the mirostructure and electrochemical properties of the Li4Ti5O12was systematically investigated. It was found that when Nb5+doped (x=0.05) and Al3+doped (y=0.1), LiTi4.95Nbo.osO12and Li3.9Al0.1Ti5O12had the best electrochemical performance, its crystal structure has not changed, also spinel crystal structure, exhib-ited a uniform particle size distribution, particle size in the range of0.5-1μm. At the rate of1C and IOC, the initial discharge capacities of Li4Ti4.95Nb0.05O12were147.0mAh/g and123.3mAh/g, respectively. After fifty cycles, it remained at140.7mAh/g and105.9mAh/g, with a retention rate of capacity being95.7%and85.8%. Equally, for the material of Li3.9Al0.1Ti5O12the dicharge capacities were originally137.5mAh/g and115.8mAh/g. and fifty cycles later, it remained at131.5mAh/g and95.8mAh/g, with a retention rate of capacity being95.5%and82.7%, respectively. After metal lattice dopin modification, both the rate capability and the cycle performance of as-prepared samples were significantly improved.Under an optimized synthetic process through high temperature solid-state reac-tion, and by modifying the surface of samples via facile electroless deposition of Ni, a composite material of LiTiO12/Ni was prepared. Also, the impact of reaction time on the performance of sample materials was explored. The result shows that composite materials prepared on the basis of electroless reaction for lOmin had the best per-formance. It had a cubical phased and spinel typed crystal structure and exhibited a uniform particle size distribution. At the charge/discharge rate of1C and5C, its dis-charge capacities were149.8mAh/g and132.5mAh/g, respectively. After fifty cycles, it remained at144.1mAh/g and124.0mAh/g, with a retention rate of capacity being96.2%and93.6%, and showed the good performance and cycle performance. |
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