Direct Measurements of Effective Electronic Transport in Porous Li-Ion Electrodes

An accurate assessment of the electronic conductivity of electrodes is necessary for understanding and optimizing battery performance. The bulk electronic conductivity of porous LiCoO2-based cathodes was measured as a function of porosity, pressure, carbon fraction, and the presence of an electrolyte. The measurements were performed by delamination of thin-film electrodes from their aluminum current collectors and by use of a four-line probe. FIB/SEM (focused ion beam/scanning electron microscope) imaging was used to correlate the electrode microstructure to electronic conductivity. The introduction of electrolyte to dry electrodes reduced electronic conductivity by around 60%.