Effect of Microstructure on the Ionic Conductivity of an All Solid-State Battery Electrode

In literature, the ionic conductivity of solid electrolytes is often discussed as one of the most important properties of an all solid-state battery. However, the behavior of the electrolyte inside a composite electrode and the influence of electrode structure on the ionic conductivity is neglected in most of the studies. In this work we manufactured model electrodes with clearly defined structures by using electrochemically inert glass particles as model active material with six different volume fractions and four different particle sizes, respectively. Higher volume fractions and smaller particles led to a decrease of ionic conductivity down to two decades due to emerging pores and a rise of tortuosity. Beneath the ionic conductivity the interface resistance between Li-metal and model electrodes was investigated, clearly indicating that high volume fractions of small active materials led to higher interface resistances. Finally, a model is introduced to predict the effective ionic conductivity of a solid electrolyte within an all solid-state battery electrode by just knowing the volume fraction of active material.