天然石墨的复合改性研究

Surface modification of natural graphite for lithiumion batteries

国产天然鳞片微粉石墨具有较高的比容量 ,但它与溶剂的相容性差 ,高倍率充 /放电能力差 ,用环氧树脂热解碳对石墨进行复合改性处理 ,一方面改变石墨的表面状态 ,并使石墨层间结合力得到加强 ,改善了石墨材料与溶剂的相容性 ;另一方面还可以改变石墨片状颗粒的形状 ,减轻它在制膜过程中的择优取向 ,有利于锂离子在石墨中嵌入和脱出 ,从而提高石墨材料的高倍率充 /放电能力。本文主要阐述了用环氧树脂热解碳对国产天然石墨进行改性处理工艺 。

Natural flake graphite powder from Shandong,China showed high specific capacity when cycling at low rate, but their high rate capability and compatibility with electrolytes were poor. The modification of graphite powder embedded into epoxy resin could improve the compatibility with electrolytes due to the existence of a hard carbon layer surrounding the graphite particles. The particle shape of the graphite epoxy coke composite looked blocky, that diminished their preferable orientation. The hard carbon layer and less preferable orientation were beneficial to the kinetics of lithium ion intercalation and deintercalation, so the composite showed much better rate capability.The synthesis of the graphite epoxy coke composites and their electrochemical properties were described.