| 研究概要 |
This research consists of two major parts. First, we synthesized and characterized silicon oxide nanowires (SiOx NWs)
having Si nanoparticles (Si NPs) at their tips to investigate the growth mechanism of the NWs. Second, we evaluated the NWs as anodes of lithium ion battery (LIBs).
Products from the laser vaporization of targets of four types, Si, 50/50 Si/SiO2, 10/90 Si/SiO2, and SiO2, without the addition of any metal catalysts in the presence of high-pressure Ar gas were characterized by transmission electron microscopy and related techniques. Amorphous SiOx NWs were only observed for the products from the Si and Si/SiO2 targets. We proposed a novel mechanism for the growth of the NWs, in which nuclei of the NWs are formed on the Si-rich molten SiOx NPs due to precipitation of SiOx via its supersaturation. We also found that crystalline germanium NWs surrounded amorphous carbon layers having NPs at their tips were able to be grown.
For the evaluation of the SiOx NWs as anodes of LIBs, we used a liquid electrolyte composed of ethylene carbonate, diethylene carbonate, and so on. From the measurement of the charge-discharge curves, charge and discharge capacities were found to be about 1100 mAh/g, which are more than three times of those of commercially available LIBs, over 90 cycles.
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