Lithium Silicide Nanocrystals: Synthesis, Chemical Stability, Thermal Stability, and Carbon Encapsulation

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• 作者：Jacqueline E. Cloud ; Yonglong Wang ; Xuemin Li ; Tara S. Yoder ; Yuan Yang ; Yongan Yang
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：October 20, 2014
• 年：2014
• 卷：53
• 期：20
• 页码：11289-11297
• 全文大小：657K
• ISSN：1520-510X

文摘

Lithium silicide (Li_xSi) is the lithiated form of silicon, one of the most promising anode materials for the next generation of lithium-ion batteries (LIBs). In contrast to silicon, Li_xSi has not been well studied. Herein we report a facile high-energy ball-milling-based synthesis of four phase-pure Li_xSi (x = 4.4, 3.75, 3.25, and 2.33), using hexane as the lubricant. Surprisingly, the obtained Li_3.75Si phase shows significant downward shifts in all X-ray diffraction peak positions, compared with the standard. Our interpretation is that the high-energy ball-mill-synthesized Li_3.75Si presents smaller internal pressures and larger lattice constants. The chemical-stability study reveals that only surface reactions occur after Li_4.4Si and Li_3.75Si are immersed in several battery-assembly-related chemicals. The thermal-stability study shows that Li_4.4Si is stable up to 350 掳C and Li_3.75Si is stable up to 200 掳C. This remarkable thermal stability of Li_3.75Si is in stark contrast to the long-observed metastability for electrochemically synthesized Li_3.75Si. The carbon encapsulation of Li_4.4Si has also been studied for its potential applications in LIBs.