  The solid-state diffusion coefficient of the electrode active material is one
of the key parameters in lithium-ion battery modelling. Conventionally, this
diffusion coefficient is estimated through the galvanostatic intermittent
titration technique (GITT). In this work, the validity of GITT and a faster
alternative technique, intermittent current interruption (ICI), are
investigated regarding their effectiveness through a black-box testing
approach. A Doyle-Fuller-Newman model with parameters for a
LiNi$_{0.8}$Mn$_{0.1}$Co$_{0.1}$O$_2$ electrode is used as a fairly faithful
representation as a real battery system, and the GITT and ICI experiments are
simulated to extract the diffusion coefficient. With the parameters used in
this work, the results show that both the GITT and ICI methods can identify the
solid-state diffusion coefficient very well compared to the value used as input
into the simulation model. The ICI method allows more frequent measurement but
the experiment time is 85% less than what takes to perform a GITT test.
Different fitting approaches and fitting length affected the estimation
accuracy, however not significantly. Moreover, a thinner electrode, a higher
C-rate and a greater electrolyte diffusion coefficient will lead to an
estimation of a higher solid-state diffusion coefficient, generally closer to
the target value.
