On the electrochemical impedance response of composite insertion electrodes – Toward a better understanding of porous electrodes

• Published in: Electrochimica acta Vol. 295; pp. 787 - 800
• Main Authors: Gruet, David, Delobel, Bruno, Sicsic, David, Lucas, Ivan T., Vivier, Vincent
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.02.2019; Elsevier BV; Elsevier
• Subjects: Chemical Sciences; Electric power; Electrochemical impedance spectroscopy; Electrodes; Electrolytes; Engineering Sciences; Lithium-ion batteries; Mathematical models; Modeling; Porosity; Porous electrode; Single particle; Solid phases; Lithium-ion batteries; Porous electrode; Modeling; Single particle; Electrochemical impedance spectroscopy
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2018.10.115

Electrochemical Impedance Spectroscopy (EIS) is a powerful tool to assess and understand the degradation of Li-ion battery (LIB) performances during operation (i.e. upon charge and discharge cycles). The full interpretation of EIS diagrams associated to complex electrode/electrolyte interfaces is however tedious. An analytical solution for the electrochemical impedance of a porous electrode composed of spherical intercalation particles in contact with concentrated electrolyte is presented herein. The proposed model which is based on the concentrated solution theory previously developed but which also accounts for kinetic limitations, and both solution-phase and solid-phase diffusion limitations, can predict the EIS response of a porous electrode at any state of charge using a limited set of parameters. Moreover, the developed model can predict the optimal porosity of the electrode to be targeted during the manufacturing process for the best cycling performances depending on the composition of the electrode (volume fractions of active material, binder and conductive agent).