基于电化学阻抗谱的锂离子电池析锂检测方法

Lithium plating identification based on electrochemical impedance spectra of lithium ion batteries

根据无析锂和析锂锂离子电池在不同温度下电化学阻抗谱变化趋势,应用等效电路模型分别拟合电化学阻抗谱中的Ohm阻抗和固体-电解液界面阻抗,提出了EIS-Ohm法和EIS-SEI法,利用扫描电镜和化学方法对析锂检测方法进行了验证。随着温度升高,析锂电池的电化学阻抗谱中的Ohm阻抗先增大后减小,固体-电解液界面阻抗变化较小;扫描电镜观察和化学方法确定了电池电极表面析出锂金属形貌和化学变化特性。结合电池工作温度(-10~60℃)和检测时间(>21 min),讨论了2种析锂检测方法的可行性。结果表明:基于电化学阻抗谱开发的2种检测方法能够清晰地判断电池发生析锂现象,这一快速、非解体检测方法对电池寿命和安全管理具有重要意义。

The EIS-Ohm method and the EIS-SEI method were proposed based on the variation tendency of electrochemical impedance spectroscopy(EIS)in different temperatures for the lithium ion batteries with and without lithium plating,and the equivalent circuit model was applied to fit the Ohmic impedance and the solidelectrolyte interface impedance in the EIS respectively.With temperature increase,the EIS of the lithium plating batteries showed an increase and then a decrease in Ohmic impedance,while the impedance at the solidelectrolyte interface showed a smaller change.Scanning electron microscopy(SEM)and chemical methods were used to determine the morphology and chemical transformation of the plating lithium metal from the electrode surface.The feasibility of two lithium identification methods was discussed by combining the operating temperature(-10~60℃)and detection time(>21 min)of the battery.The results show that the two detection methods developed based on electrochemical impedance spectroscopy can clearly identify the lithium plating,and the rapid,non-dissembling identification methods have important applications for battery life and safety management.