| The demand for developing sustainable and green energy sources are at the top of the agenda in today’s energy-based society, with growing concerns over environmental issues and the stretched energy situation. Li-ion batteries, considered to be the most important energy storage and conversion technology with prominent advantages of high energy and power density as well as long cycling life, have aroused much researchers’attention. Li-ion batteries consisted of anode, cathode, electrolyte and diaphragm. The electrochemical performance of Li-ion batteries strongly depends on the electrode properties, and a prudent selection of electrode materials including anodes and cathodes plays a central role. TiO2 have been intensively investigated as important anodes for Li-ion batteries due to their high safety and excellent cycling stability. Thus, TiO2-based materials were chosen as research subjects to improve the specific capacity, cycling stability and rate performance for Li-ion batteries. The research contents of this paper are as follows:1、A new type of TiO2-B nanoribbons anchored with NiO nanosheets (TiO2@NiO) is synthesized via a hydrothermal process and subsequent homogeneous precipitation method. XRD analysis indicates that TiO2-B and cubic NiO phases exist in the composites. According to SEM images, the morphology of TiO2@NiO hybrid material is unique, similar to that of leaf mosaic in biological system. According to electrochemical investigations, the nanostructured hybrid material as anode exhibits superior initial charge/discharge capacity and capacity retentions. The initial discharge capacity of TiO2@NiO hybrid nanostructure is 395 mAh·g-1, and the capacity remain 380 mAh·g-1 after 50 charge/discharge cycles, which is about 96.2% capacity retentions and 7.8%higher than that of pristine TiO2-B nanoribbons.2、The spinel LiMn2O4 was modified with TiO2-B nanobelts to improve its specific capacity and cycling performance. TiO2-B/LiMn2O4 composites were fabricated by a facile liquid phase mixing method. The results show that TiO2-B nanobelts are uniformly distributed in LiM2O4 particle. Compared with bare LiMn2O4, TiO2-B/LiMn2O4 composite cathode material shows enhanced specific capacity of 129 mAhg-1 and improved cycling stability. After 50 cycles, the 2.0 wt.% TiO2-B nanobelts modified LiMn2O4 exhibited the capacity retention of 94.5%. The improvement of the electrochemical performance is attributed to suppression of Mn2+ dissolution, higher structural stability of the composite.3、A new type of LiMn2O4@TiO2 cathode material with shape similar to honeycomb was synthesized via a simple sintering process. The spinel LiMn2O4 was modified with anataseTiO2 to improve its specific capacity and cycling performance. The morphology and structure of the samples were characterized by means of X-ray diffraction and scanning electron microscopy. The XRD results show that the main diffraction peaks of LiMn2O4@TiO2 moved to the left obviously, which meaning that the interlayer spacing is increased. According to SEM images, TiO2 realized not only doping modification but also coating modification. And, electrochemical testing show that LiMn2O4@TiO2 composite cathode material shows enhanced specific capacity of 127 mAh/g and improved cycling stability, compared with bare LiMn2O4. After 200 cycles between 3.0 and 4.3V at 0.5C charge/discharge rate at room temperature, the 0, 2.0,3.0,4.0 and 5.0 wt.% titanium sol modified LiMn2O4 exhibited the capacity retention of 86.4,87.8,90.6,88.2, and 86.2%, respectively. That is to say, the capacity retention rate of 3.0 wt.%titanium sol modified LiMn2O4 is obviously higher than that of bare LiMn2O4. |
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