针对微晶石墨振实密度低和首次库仑效率低的缺点,采用真空浸渍-炭化工艺对微晶石墨进行沥青炭包覆改性,利用XRD、拉曼光谱和 SEM等分析了炭包覆前后微晶石墨的结构和表面形貌,利用比表面测试仪测试了样品的BET比表面积,利用振实密度仪测定振实密度,并通过恒电流充放电和循环伏安等测试了样品的电化学性能。结果表明,炭包覆后微晶石墨的石墨化度略有降低,拉曼R 值由0.63增大至0.85；颗粒表面更光滑平整,BET 比表面积降低0.9m2/g,振实密度从0.95g/cm3提高至1.08g/cm3；不可逆容量损失从121mAh/g减小到44mAh/g,可逆容量从300mAh/g 提高到320mAh/g,首次库仑效率从71.2%提高到87.4%,而且循环性能得到明显改善。
To address the shortcomings,such as low tap density and low first cycle Coulombic efficiency of mi-crocrystalline graphite when used as lithium ion battery anode,the paper investigated the liquid phase coating for microcrystalline graphite using vacuum impregnation method.The microscopic structure of the coated sam-ple was tested with XRD,Raman spectrum.The surface feature was characterized by SEM and nitrogen ad-sorption-desorption.The performance of the sample was determined by galvanostatic test and CV test.It shows that after the modification,the degree of graphitization was reduced slightly,the Raman R value increases from 0.63 to 0.85,the surface of the graphite particles become neater and smoother,the BET specific surface area decreases by 0.9m2/g,and the tap density increases from 0.95 to 1.08g/m3 .The electrochemical performance of the modified graphite was significantly improved.and the irreversible capacity was reduced from 1 2 1 to 44mAh/g.The reversible capacity increases from 300 to 320mAh/g,the initial Coulombic efficiency increases from 71.2% to 87.4%.The cycle stability was improved significantly.
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