废人造石墨用作锂电池负极的表面氧化成膜改性

Surface Oxidation and Similar SEI Formation on Scrap Artificial Graphite as Negative Material of Lithium Ion Batteries

废人造石墨在室温下经30%的双氧水氧化,真空干燥后进一步用LiOH浸渍处理或与Li_2CO_3共混后在N_2保护下升温处理,在人造石墨表面形成类SEI膜用作锂离子电池的负极材料.X射线衍射和X射线光电子能谱测试分析表明,表面氧化成膜处理使得人造石墨表面形成以Li_2CO_3为主要成分的膜层,石墨颗粒表面的氧含量增加,含氧官能团增多.样品的充放电测试结果表明:氧化成膜样品的放电容量均超过323mAh/g,均大于处理前的255.5 mAh/g,前50次循环的可逆放电容量基本没有衰减,仍保持在317mAh/g以上,说明氧化成膜处理有利于减少形成SEI膜时锂离子的消耗,抑制溶剂和电解质的分解,充放电效率提高.

Scrap artificial graphite used as negative material of lithium ion batteries was firstly oxidized with 30% H2O2 at room temperature, and then modified by two methods： LiOH impregnation and molten Li2CO3 coating technique with N2 protection. X-ray diffraction and X-ray photoelectron spectroscopy analysis show that these two modification methods can form Li2CO3 film as similar SEI film on the graphite surface, and increase oxygen content and oxygenic functional groups on the graphite surface. Compared with that of untreated artificial graphite, the charge capacities of treated samples with oxidation and similar SEI formation increase from 255.5mAh/g to 323mAh/g upward, and the reversible capacity decreases a little in the first fifty cycles, keeping 317mAh/g. It proves that surface oxidation and similar SEI formation treatment can reduce lithium ion consumption, restrain decomposition of solvent and electrolyte, and improve coulombic efficiency.