Determination of the diffusion coefficient of an inserted species in a host electrode with EIS, PITT and GITT techniques Battery – Application Note 70

The diffusion coefficients of the inserted species are key parameters that determine the battery cell properties. The larger the diffusion coefficient value is, the faster or, more correctly,  the more facile the insertion/desinsertion of the inserted species is, and eventually, the better the battery performance is.

Chronoamperometry and chronopotentiometry are classical techniques used to measure diffusion coefficient in the case of a semi-infinite linear diffusion [1-3]. In the case of bounded diffusion, several techniques and analyses are available such as Levich analysis and EIS fitting with the Winf element. Impedance analysis can also performed on commercial Li-ion batteries to try to derive information of the diffusion coefficient of the inserted species.

In this note we will first present the methods to obtain the diffusion coefficient in the case of a system where a restricted linear diffusion reaction is involved, using results from Electrochemical Impedance Spectroscopy (EIS), Galvanostatic Intermittent Titration Technique (GITT) and Potentiostatic Intermittent Titration Technique (PITT) experiments.