催化热处理对MCMB作为锂离子电池负极材料电化学性能的影响

EFFECT OF CATALYTIC HEAT TREATMEAT ON THE ELECTROCHEMICAL PERFORMANCE OF MESO-CARBON MICROBEADS AS ANODE MATERIAL FOR LITHIUM-ION BATTERIES

用硝酸铁(Fe(NO3)3.9H2O)浸渍MCMB生球,在1500℃下进行催化热处理。采用X射线衍射、扫描电镜、恒流充放电、电化学交流阻抗等对样品进行测试和表征。结果表明,经催化热处理的MCMB表面碳层石墨化程度提高,处理后的MCMB在0.2mA/cm2电流密度下的首次可逆容量从相同温度下直接炭化样品的146mA.h/g提高至233mA.h/g,第30次循环放电容量与第1次循环放电容量的比值从68%提高至100%。交流阻抗结果显示,适量添加硝酸铁可以有效降低SEI膜(固体电解质膜)电阻及电极反应电荷传递电阻,有效地提高电极的电化学性能。

Mesocarbon microbeads （MCMB） were heat treated at 1 500℃ in the presence of ferric nitrate. The morphology, strucuture and electrochemical properties of these samples were characterized by XRD, SEM, charge-discharge and AC impedance measurements. It was found that graphitization degree of MCMB after catalytic heat treatment was improved. When these samples were used as anode materials for lithium ion batteries, the first reversible capacity reached 233 mA · h/g, which was higher than the value 146 mA · h/g of the sample without ferric nitrate addition, and showed excellent cyclability with the cycle efficiency approaching 100%. The kinetic properties of samples were characterized by AC impedance measurement. It was indicated that the proper ferric nitrate addition can reduce both the SEI film resistance and the charge- transfer resistance, and improve the electrochemical performance of MCMB anode.