酚醛树脂包覆和预成膜共改性石墨作为锂离子电池负极材料的研究

以天然石墨为原料,球磨过筛得到颗粒均一的球形颗粒。酚醛树脂作为碳源对球磨后石墨进行包覆,经过高温碳化处理,在天然石墨表面形成一层碳包覆层,再对包覆后石墨用聚二甲基硅氧烷进行表面预成膜处理。采用X射线衍射仪、扫描电子显微镜和LAND电池测试系统等对共改性石墨进行结构、形貌和电化学性能分析。XRD分析显示,共改性后的石墨层间距d002和无序化程度增加,说明在石墨的表面形成了一定的包覆层。SEM图片中可以看出改性后的石墨颗粒致密均匀且较为圆滑,这种结构使得石墨颗粒表面积适当减小,电化学性能得到提高。电化学性能测试结果,采用共改性后的石墨在0.1C首次放电比容量达到362mA·h/g,首次库伦效率为92%,100个循环后容量仍保持为最高容量的98.6%。

Phenolic Resin Coated and Prefilm Modified Graphite as Lithium Battery Cathode Materials Research

The uniformity spherical graphite particles were made by ball milling sieve processing with natural graphite as raw material.Carbon-coated natural graphite composite was prepared by carbonization of Phenolic resin-coated natural graphite at high temperature.With polydimethyl siloxane form surface film processing on the coated-graphite,X-ray diffraction（XRD）,scanning electron microscopy（SEM）and land battery test system were used to characterize the crystal structure,morphology and electrochemical properties of samples.XRD results showed that Phenolic successfully coated on the surface of natural graphite because d002 and the disorder degree increased SEM images indicated that graphite particles is uniform and smooth.The electrochemical performance was improved as graphite surface area reduced by this structure.Electrochemical performance revealed that the capacity of compound modification graphite was 362mA·h/g at 0.1C,Coulomb efficiency is 92%for the first time,after the 100 cycle the capacity remains as the highest capacity of 98.6%.