Present LIBs for EV-use possess large power densities by the sacrifice of energy densities in order to shorten the charging time. In the practical LIBs for portable devices, dense and thick composite electrodes are used. In this case, the ion transport of electrolyte solution through the pores in the composite electrodes becomes a slow process. In order to enhance the energy densities with remaining high power densities, the ion transport rate should be increased for the dense and thick composite electrodes. Unfortunately, to develop dense and thick electrodes with high power densities, fundamental understanding of the ion transport in composite electrodes has not been clear. In this study, ion transportation behavior was investigated with ac impedance spectroscopy.

To focus on the impedance of ion transportation of electrolyte through the pores in composite electrode, we prepared anodic aluminum membranes with homogeneous macro- and meso- pores. In addition, graphite composite electrodes were also used. As a result, we obtained semi-circles, and this semi-circle was assigned to the ion transport process through the graphite composite electrode. The detail analysis will be presented at the meeting.