【作者】 王朋；

【导师】 贺德衍；

【作者基本信息】 兰州大学 ， 凝聚态物理， 2013， 硕士

【摘要】 制备具有更大容量,更高功率密度和更长循环寿命的下一代锂离子电池,关键是发展具有高性能的电极材料。硅材料由于具有10倍于碳的理论比容量、材料自身在地壳中储量丰富、无毒等优点,有望成为下一代锂离子电池理想的负极材料,因此也成为当前研究的热点。然而,Si材料在嵌锂、脱锂过程中存在严重的体积膨胀,如何解决其体积膨胀所造成的电池容量快速衰减等问题成为目前研究所面临的最大挑战。本论文以获得高性能的Si电极为目标,将湿化学方法制备的纳米结构SiO2作为前驱物和模板,制备出Si的纳米管和纳米多孔结构。。方面,采用静电纺丝技术制备出SiO2纳米管,通过镁热还原并结合后续的酸洗除杂制备了Si纳米管,研究了给液速率、外加电压、接受距离等工艺参数对静电纺丝过程的影响,证实了可以通过控制这些工艺参数实现对碳包覆Si纳米管的可控制备。另一方面,我们以SiO2纳米球作为前驱物和模板,利用镁热还原反应制备了多孔Si材料。与传统的单晶Si片腐蚀制备相比较,这种方法成本低廉,可实现多孔Si的可控制备。研究了所制备的多孔Si作为锂离子电池负极材料的电化学性能。实验发现,所制备的多孔Si材料的首次放电比容量为1245mAh/g,充电比容量为963mAh/g,首次库仑效率为77.3%,并且具有良好的循环稳定性。更多还原

【Abstract】 Exploring electrode materials with high performance is critical for fabricating the next generation lithium ion battery with larger capacity, higher power density and longer cycle life. Silicon materials are expected to be the cathode electrode material of the next generation lithium ion battery and have become a research focus due to their high theoretical capacity which is10times than that of carbon, abundance in the earth’s crust, non-toxic property, etc. However, there exists large problems with silicon materials about its volume expansion in lithium and delithiation process, how to solve the fast decay of the battery capacity caused by serious volume expansion is a big challenge in the current research.This thesis aim to obtain a high performance Si electrode. The wet chemical methods was used to synthesize nanostructured SiO2, which acted as precursor and the template in the fabrication of silicon nanotubes and nano-porous structure.On one hand, SiO2nanotubes was fabricated by the electrospinning method, then Si nanotubes was fabricated by Magnesium thermal reduction along with subsequent pickling impurity removing. The influence of the parameters such as the liquid rate, applied voltage, receiving distance on the electrospinning process was researched, and finally it was confirmed that carbon coated Si nanotube can be fabricated in a controlled way by adjusting the above parameters.On the other hand, using SiO2nanoparticles as precursor and template, porous silicon material was fabricated by magnesium thermal reduction. Compared with conventional fabrication based on corrosion of monocrystalline Si wafer, this method is inexpensive and can realize controlled fabrication of porous Si. By studying the electrochemical properties of the fabricated porous Si based lithium-ion battery cathode materials, it is found that the porous Si materials have an initial discharge capacity of1245mAh/g, a charging capacity of more than963mAh/g, an initial coulombic efficiency of77.3%, and a good cycling stability.更多还原