LiCoO2 electrode/electrolyte interface of Li-ion batteries investigated by electrochemical impedance spectroscopy
Date
2007Author
Zhuang QuanChao
庄全超
Xu JinMei
Fan XiaoYong
樊小勇
Wei GuoZhen
Dong QuanFeng
董全峰
Jiang YanXia
姜艳霞
Huang Ling
黄令
Sun Shigang
孙世刚
Collections
- 化学化工-已发表论文 [14469]
Abstract
The storage behavior and the first delithiation of LiCoO2 electrode in 1 mol/L LiPF6-EC:DMC:DEC electrolyte were investigated by electrochemical impedance spectroscopy (EIS). It has found that, along with the increase of storage time, the thickness of SEI film increases, and some organic carbonate lithium compounds are formed due to spontaneous reactions occurring between the LiCoO2 electrode and the electrolyte. When electrode potential is changed from 3.8 to 3.95 V, the reversible breakdown of the resistive SEI film occurs, which is attributed to the reversible dissolution of the SEI film component. With the increase of electrode potential, the thickness of SEI film increases rapidly above 4.2 V, due to overcharge reactions. The inductive loop observed in impedance spectra of the LiCoO2 electrode in Li/LiCoO2 cells is attributed to the formation of a Li1-x CoO2/LiCoO2 concentration cell. Moreover, it has been demonstrated that the lithium-ion insertion-deinsertion in LiCoO2 hosts can be well described by both Langmuir and Frumkin insertion isotherms, and the symmetry factor of charge transfer has been evaluated at 0.5.