化成电压对锂离子电池性能的影响

Effects of formation voltage on performance of Li-ion battery

研究化成电压对钴酸锂(Li Co O2)正极、石墨负极的锂离子电池性能的影响。从电池容量、倍率、阻抗、存储和循环性能等方面,并从负极固体电解质相界面(SEI)膜形成机理的角度,分析电池性能的差异。化成充电截止电压设定为3.70 V,与3.80 V相比,电池的容量、倍率、阻抗和存储等性能都有所改善。不同化成截止电压生成的SEI膜厚度不同,3.80 V时生成的SEI膜外层疏松,有机锂盐层增厚,因有机层稳定性差导致电芯的存储性能变差。

The effect of formation processes on performance of Li-ion battery, whose cathode and anode materials were lithium cobaltate （LiCoO2 ） and graphite, was analyzed. The differences of battery performance were analyzed through the anode solid electrolyte interphase（SEI） film forming mechanism, which was taken into account the capacity, ratio, impedance, storage and cycle performance. Compare to the battery with 3.80 V, the battery with 3.70 V of formation charge cut-off voltage had better performance in capacity, rate, impedance and storage. The different thickness of SEI film was variable with different formation charge cut-off voltage, the SEI film with 3.80 V of formation charge cut-off voltage had a thicker layer of organic lithium salt with a porous morphology. The organic layer was instable, which made the storage performance of battery worse.