Li2CO3添加剂对石墨电极性能的影响

Effects of Li_2CO_3 Additive on the Performance of Graphite Electrode

运用电化学阻抗谱(EIS)和循环伏安法(CV)研究了在1mol/LLiPF6-EC(碳酸乙烯酯):DMC(碳酸二甲酯)电解液中添加Li2CO3对石墨电极性能的影响及机制.CV研究结果表明,在1mol/LLiPF6-EC:DMC电解液中添加Li2CO3能够有效抑制石墨电极首次充放电过程中碳酸乙烯酯(EC)的单电子还原过程,即还原分解产生乙烯和碳酸锂的过程,进而改善石墨电极的电化学循环性能.EIS研究结果表明,在添加Li2CO3的1mol/LLiPF6-EC:DMC电解液中,石墨电极表面的固体电解质相界面膜(SEI膜)具有较强的黏弹性,可以更好地适应锂离子嵌入过程中石墨颗粒体积的微小变化,从而使锂离子的嵌入过程更容易进行.

Effects of Li2CO3 additive in 1 mol/L LiPF6-EC（ethylene carbonate）：DMC（dimethyl carbonate） electrolyte（1：1,mass ratio） on electrochemical performance of graphite electrode were investigated by cyclic voltammetry（CV） and electrochemical impedance spectroscopy（EIS） in the first lithiation process.The CV results show that electrochemical performance of the graphite electrode is improved by adding Li2CO3 into 1 mol/L LiPF6-EC：DMC electrolyte and the single electron reduction of EC,namely decomposes to ethylene and Li2CO3,is largely suppressed in the electrolyte with Li2CO3 additive in the first lithiation,thus reducing the consumption of the electrolyte and Li-ions in the solid electrolyte interface film（SEI film） formation process.EIS results display that the SEI film formed on the graphite surface in the electrolyte with Li2CO3 additive shows better viscoelasticity,and it can well accommodate the tiny volume change resulted from the Li-ion intercalation process,which makes Li-ion insertion and desertion much easier.The above results suggest that Li2CO3 could be used as a promising electrolyte additive for lithium ion batteries electrolyte.