Tai Sun

Synergetic effects of hydrogenated Mg3La and TiCl3 on the dehydrogenation of LiBH4

To improve the hydrogen storage performance, Mg3La alloy and TiCl3 is ball milled simultaneously with LiBH4 to yield a designed composition. It has been revealed that there is a synergistic effect of Mg3La alloy and TiCl3 on the dehydrogenation of LiBH4, which improves the dehydrogenation performance when compared to adding either hydrogenated Mg3La or TiCl3 alone. 4.3 wt% of H2 can be released within 10 min at 400 °C in the LiBH4 + Mg3La + TiCl3 system. The dehydrogenation activation energy of this system is 52.6 kJ mol−1, which is much lower than that of pristine LiBH4. In addition, the LiBH4 + Mg3La + TiCl3 system preserves fast dehydrogenation kinetics and stable hydrogen storage capacity in the re-/dehydrogenation cycles.

Effect of Graphite Matrix on Property of Silicon/Carbon Composite Anode Material for Lithium-Ion Battery

Nano-silicon carbon coated and combined with different graphite matrixes was synthesized by ball milling，and spray dying-pyrolysis methods. The physical properties of Si/C composites were detected by X-ray diffraction（XRD），scanning electron microscopy（SEM），and all composites were completely coated by a carbon layer. Their electrochemical performances were studied by galvanostatic cycle and electrochemical impedance spectra. These analyses show that the discharge specific capacity of composited anode based on expanded graphite exhibits the best comprehensive electrochemical performance such as cycle stability and initial charge/discharge efficiency among various composites，owing to the co-effect of expanded graphite and amorphous carbon layer as the structural stabilizer and conductive additives to prevent the volume change and enhance the electronic conductivity of the composites. The discharge specific capacity is 700.9 mAhg-1 at a current density of 100mAg-1，initial charge/discharge efficiency is 77.4%. After 30 cycles，the capacity retention rate can reach 87.7%.

Synthesis and Electrochemical Performance of Silicon/Carbon Composite Anodes through Ball Milling and Spray Drying Pyrolysis Process

A facile method was developed to synthesize amorphous carbon coated nano-sized silicon and graphite by using glucose or pitch as organic carbon source, nano-sized silicon particles were uniformly coated onto the artificial graphite by combined ball milling and spray drying pyrolysis, and the effect of binder types, binder amounts on the precursor morphology, feed rate and spray pressure on the electrochemical performance were investigated in detail. The partial size, surface morphology and electrochemical performances of the as-synthesized powders were analyzed by particulate size description analyzer (PSDA), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and constant current charge/discharge tools. It is found that, citric acid and binder are important for improving the free-aggregation of nano-sized silicon and the morphologyof combined silicon and graphite. Therefore, under the optimal experimental conditions, amorphous carbon from pitch coated nano-sized silicon and graphite composite anodes exhibits much higher electrochemical performance. It can deliver the first discharge specific capacity of 796.3mA·h/g at a current density of 100 mA/g, as well as 85% of initial coulombic efficiency. Additionally, the discharge specific capacity retains 724.9mA·h/g, and the discharge capacity retention of a half cell system is 91% after 50 cycles.

Study on Preparation of Si/C Anode Material by Spray Dying and Carbonization

Si/C composites were prepared by spray dying and carbonization process using silica powder, artificial graphite and glucose as raw materials. The physicochemical property and electrochemical performance of composite materials were characterized by XRD, SEM, constant current charge-discharge and cyclic voltammeter (CA) test, respectively. The results show that composite anode materials have pure phase structure with particle size of 5~20μm, and its special structure that silicon and graphite particles are constructed can exhibit good electrochemical performance. The initial discharge specific capacity of Si/C composites is 1033.2mAhg-1 at a current density of 100mAg-1.While the current density is as high as 600mAg-1, the discharge specific capacity is 584.2mAhg-1, and the first cycle coulombic efficiency is 77.3% at 100mAg-1.The mechanism of capacity fading of Si/C composites is discussed by different morphology characterization after 100 cycles.