Rapid Determination of the Li-Ion Diffusion Coefficient in Intercalation Electrodes by Intermittent Current Interruption

Abstract

The galvanostatic intermittent titration technique (GITT) has long been regarded as the go-to method for determining the diffusion coefficient of Li-ions in the intercalation electrode materials at various states of charge (SoC). However, the GITT is a stand-alone technique and notoriously time-consuming. Here, we present an efficient alternative to GITT: the intermittent current interruption (ICI) method. From Fick’s laws, it is demonstrated that the ICI method renders the same information as GITT. Both GITT and ICI are experimentally benchmarked by electrochemical impedance spectroscopy (EIS) in a half-cell of lithium nickel-manganese-cobalt oxide (NMC 811). The results from the three employed methods match each other where the assumption of semi-infinite diffusion applies, thereby demonstrating the applicability of using a more efficient technique to determine the lithium diffusivity. Moreover, the nondisruptive nature and the compatibility with galvanostatic cycling make the ICI method ideal for online diagnoses and operando characterization of Li-ion batteries.Figure: Diffusion coefficient (D) of Li-ions in NMC 811 plotted against the potential (E) in measurements employing GITT and ICI methods. Figure 1