亚硫酰基存在下石墨负极界面的SEI膜机制

使用恒电流充放电和粉末微电极循环伏安方法研究了亚硫酰基添加剂对碳酸丙烯酯(PC)基电解液电化学嵌脱锂性能的影响。研究表明, 所使用的亚硫酰基添加剂可以有效地抑制石墨负极在PC基电解液中首次充电过程的层离现象, 添加剂活性基团的吸电子能力是决定添加剂在电极表面固体电解质相界面(SEI)膜形成电位的重要因素, 成膜电位与Li 在电解液中的溶剂化状况无关,表明电解液组分在电极界面的还原反应, 特别是还原反应的初始反应是电子从电极本体到电解液组分活性中心的迁移。在所使用的亚硫酰基添加剂中, 亚硫酸乙烯酯(ES)可以在碳负极/电解液相界面形成优良的SEI膜, 有望在石墨类负极材料的锂离子蓄电池中得到应用。

SEI mechanism on graphite surface in presence of sulfinyl additives

The effects of sulfinyl additives (DMSO, ES, SO2 and SOCl2) on graphite electrochemical properties in PC-based electrolyte solution were investigated by using cyclic voltammetry and chronopotentiometry measurements. All the additives used were found effective in suppressing exfoliation of graphite structure. Comparison of the onset of reduction potential suggests that, not related to the solvation state of Li in the electrolyte, electron-attracting ability of the additives is the dominant factor deciding the SEI formation potential on carbon surface in the first cathodic process. This suggestion indicates that the initial reaction of electrolyte components is the electron transfer from electrode to electrolyte component of higher electrochemical activity. Among the sulfinyl additives, ES, with the advantage of producing stable and Li conductive SEI components in PC-based electrolyte, is desirable for use with graphite anode in lithium ion battery based on "rocking-chair" concept.