| During all the anode materials, Silicon (Si) has captured broad attention due to its highest theoretical specific capacity of ～3580 mAh·g-1, modest discharge potential (～0.5 V versus Li/Li+). However, the pure Si anode hasn’t realized commercial utilization due to the bad cycling stability and rate performance. Such reasons can be attributed to the bad electrochemistry behavior:(1)The large volume expansion/contraction during Li-ion insertion/extraction processes result in silicon pulverization and lose electrical contact with current collector, (2)The low electronic conductivity of silicon leading to poor rate performance at high rate charge/discharge. To solve the above-mentioned issues, this paper mainly utilize structure designing to prepare several porous silicon composites, aimed at alleviating the volume effect during cycling by the abundant pores, and thus improve the cycling stability. Meanwhile, composite of silicon and carbon/PANi are prepared to enhance the electronic conductivity of the electrode, thereby improving its rate performance. The samples are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, nitrogen adsorption, and Raman spectroscopy.Following are major results of this paper:(1) Three porous silicon anode materials are prepared through magnesiothermic reduction using SBA-15, diatomite and microsilica separately. They all exhibit good cycle stability, as the porous structure plays an important role in alleviating the stress generated during charge/discharge processes. OMP-Si, the reduction product of SBA-15, presents the best cycling stability and the highest reversible capacity. The as-prepared OMP-Si rods preserve the ordered honeycomb porous structure of SBA-15, and connect end to end, forming lotus-root like chains with high packing density. Moreover, a liquid ambient reaction model is proposed to describe the reaction mechanism between SBA-15 and magnesium powder and the formation of this lotus-root like highly ordered mesoporous structure at temperature of 660℃.(2) To improving the electronic conductivity, the OMP-Si is treated with carbon coating, the carbon layer coated on the surface of OMP-Si can provide conductive network for the electrode. Such a unique structure promotes higher reversible capacity and better capacity retention. The excellent electrochemical performance of this highly ordered mesoporous Si/C shows its promising applications in anode materials for Li-ion batteries. At the same time, to study the role of carbon during the magnesiothermic reduction, a compare sample is prepared. In detail, firstly coat SBA-15 with carbon, and then process with magnesiothermic reduction, the as-prepared sample is titled as OMP-Si/C-1. The OMP-Si/C-1 sample shows a better electrochemical performance than OMP-Si/C, higher reversible capacity and better rate performance.(3) Using OMP-Si as template, filling with anilinemonomers, and polyaniline is polymerized in the mesoporous channels to form the composite of mesoporous silicon and polyaniline. The structure not only can alleviate the volume effect of silicon during charge/discharge process with the good ductibility of PANi, but also can provide electronic conductivity for the whole electrode, accordingly enhance the cycling and rate performance of the material. After 20 times cycling, this composite still maintain a reversible capacity of 800 mAh·g-1, and the capacity still reach 220 mAh·g-1 at the current density of 2000 mA·g-1.In conclusion, this paper adopt cheap and easy available silicas with special structure as silica source and template, prepared porous silicon anode materials with good electrochemical performance by magnesiothermic reduction under moderate reaction conditions. In addition, the composites of OMP-Si and carbon/palyaniline are prepared to improve the electronic conductivity, and enhance the electrochemical performance. Such a simple and practical method increases the potential of practical utilization of silicon based anode material.
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