The production of Li-Ion battery electrodes is a highly interconnected process and many parameters
determine the functionality of the final battery cell. Therefore, characterization techniques are very
important to monitor the quality of the electrodes and to analyze deviations in electrode performance.
The impedance of the porous electrode is a characteristic performance indicator, relatively easy to
measure, and the corresponding spectra provide a comprehensive overview of characteristic timescales
of different processes. For a detailed analysis impedance spectra are commonly evaluated integrally
with the help of equivalent circuit models. However, often the performance of the electrode is affected
by local structural inhomogeneities due to compression in the calendering process or an unfavorable
binder and/or carbon black distribution. For instance, it was found that harsh drying conditions cause
binder migration to the electrode surface and consequently reduce the rate capability1. In this
contribution we interpret impedance spectra of Li-ion battery positive electrodes with the help of 3D
microstructure-resolved simulations2. This allows us to study in detail the effect of local structural
inhomogeneities on the electrode impedance and, thus, performance.
NMC electrodes with different thickness and density were prepared and characterized
electrochemically by galvanostatic cycling and electrochemical impedance spectroscopy. Impedance
spectra were recorded on symmetrical cells3 which are especially advantageous for the
characterization of electrode transport properties. Reconstructions of the electrodes were created with
the help of synchrotron tomography and a 3D stochastic structure generator4. The resulting
microstructures are then input to microstructure-resolved electrochemical simulations. With the help
of our simulations we are able to extract the contribution of the carbon black and binder network to the
overall pore transport resistance by comparing our simulations to the experimental data. Additionally,
we use different models for the spatial distribution of binder and carbon black to mimic different
drying conditions and investigate the effect on the electrode impedance and cell performance
