The importance of cell geometry for electrochemical impedance spectroscopy in three-electrode lithium ion battery test cells

The influence of geometric and electrochemical asymmetries on the impedance spectra recorded in three-electrode test cells for lithium ion batteries was investigated. These asymmetries lead to distortions such as e.g. scaling effects which appear in common Swagelok cells. Moving the reference electrode to a coaxial position in combination with a precise alignment of the electrode stack optimized the geometry of current lines, leading to reliable impedance spectra up to frequencies of 50 kHz regardless of the electrode configuration.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► EIS is a powerful tool for the analysis of lithium ion batteries. ► Impedance spectra of full cells are a sum of the impedance of each electrode. ► A reference electrode separates the working and counter electrode impedance. ► Geometric or electrical asymmetries cause distortions in impedance spectra. ► A new Swagelok-type cell was developed which prevents these distortions.