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本文详细研究了橄榄石结构磷酸盐脱嵌锂过程的控制步骤,发现就多元橄榄石结构Li(FeMnCo)PO4磷酸盐而言,碳含量比较低时在充放电曲线之间存在非对称现象.充电时与Fe2+/Fe3+电对对应的容量小于理论容量,与Co2+/Co3+电对对应的容量大于理论容量;放电时与Co2+/Co3+电对对应的容量远小于相应的充电容量,但是与Fe2+/Fe3+电对对应的放电容量远大于与该电对对应的充电容量.电极呈现出以Co2+/Co3+电对充电,以Fe2+/Fe3+电对放电的行为.作者认为在充电和放电过程中活性材料颗粒内部存在内界面,充电时内界面内部组成是Fe2+、Co2+、Mn2+和低浓度的Fe3+,而内界面外部组成是Co3+、Mn2+、Fe3+和低浓度的Co2+.非对称现象的主要原因是内界面移动速度缓慢,碳含量低时慢的内界面移动速度是电化学脱嵌锂过程的主要控制步骤.
In this paper, the control procedure of the deintercalation of lithium in olivine structure phosphate has been studied in detail. It is found that there is an asymmetry between the charge and discharge curves for the multicomponent olivine Li (FeMnCo) PO4 phosphate when the carbon content is low. The capacity corresponding to the Fe2 + / Fe3 + electrode pair is smaller than the theoretical capacity, and the capacity corresponding to the Co2 + / Co3 + electrode pair is larger than the theoretical capacity. The capacity corresponding to the Co2 + / Co3 + electrode pair is much smaller than the corresponding charge capacity during discharge, The discharge capacity corresponding to the electricity pair is much larger than the corresponding capacity of the electricity pair.The electrode shows the behavior of discharge with Co2 + / Co3 + charge and Fe2 + / Fe3 + discharge.The author thinks that during the charge and discharge, The inner interface of the inner interface is Fe2 +, Co2 +, Mn2 + and Fe3 +, while the inner interface is composed of Co3 +, Mn2 +, Fe3 + and low concentration of Co2 +. The main reason of the asymmetry phenomenon is the velocity of the inner interface Slow, slow movement of the inner interface at low carbon content is the primary control step of electrochemical deintercalation of lithium.