【摘要】 研究了氧化微扩层处理对天然鳞片石墨晶体结构、表面形貌及其电化学性能的影响。结果表明,经氧化微扩层处理后,鳞片石墨的平均层间距d002略微增大,平均晶粒尺寸显著减小,鳞片石墨颗粒表面出现刻蚀和片层剥落现象。氧化微扩层处理1 h后,鳞片石墨的首次可逆容量从331.9 m A·h/g提高至364.7 m A·h/g,首次库伦效率从86.5%提高至88.8%。经过氧化微扩层处理,石墨的平均晶粒尺寸减小,锂离子在碳层表面及边缘嵌入量增加;在石墨表面引入的纳米级孔隙结构进一步增大了锂离子存储空间;同时,对表面细小颗粒的刻蚀清除,使石墨比表面积减小,是可逆容量和首次库伦效率提高的主要原因。更多还原

【Abstract】 The effects of mild expansion treatment by oxidation on the crystal structure, surface morphology and electrochemical performance of flake graphite were investigated in this paper. The results indicate that the average interlayer distance of d002 increased slightly, while the average crystallite size decreased significantly. The treatment also causes etching on particle surface and flaking of the graphite sheet. After expansion for 1 h, the initial reversible capacity of flake graphite increases from 331.9 m A·h/g to 364.7 m A·h/g, while the initial columbic efficiency increases from 86.5% to 88.8%. The treatment improves the insertion amount of Li~+ in the surface and edge of a graphite sheet because of the decreased average crystallite size. Nanoscale pore is introduced in the surface, which provides more space for lithium ion storage. At the same time, fine particles on the surface of graphite are removed, which results in the lower specific surface area. These are the main reasons for a higher reversible capacity and initial columbic efficiency.更多还原