A Fast Alternative to the Galvanostatic Intermittent Titration Technique

Abstract

The galvanostatic intermittent titration technique (GITT) has been regarded as the go-to method for determining the diffusion coefficients of Li-ions in insertion electrode materials at various states of charge (SoC). However, the method is notoriously time-consuming. In this work, the intermittent current interruption (ICI) method, which has previously been employed to investigate the progression of internal resistances in Li-ion cells, is demonstrated to provide comparably accurate measurements of diffusion coefficients with a drastically reduced experimental time. Theoretically, it is first derived from Fick’s laws that the ICI method renders essentially the same information as GITT. Experimentally, both GITT and ICI are then compared side-by-side in a three-electrode half-cell of LiNi_0.8Mn_0.1Co_0.1O₂ (NMC811). It is shown that the results from both methods match where the assumption of semi-infinite diffusion applies. Moreover, the benefit of the comparatively non-disruptive ICI method to operando characterization methods is demonstrated via correlation of changes in the continuously monitored diffusion coefficient of Li⁺ in NMC811 to structural changes in the material by operando X-ray diffraction (XRD).

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