In order to remove irreversible capacity showed by graphite anodes at first charging process, pre-lithiation was applied to the anodes which were laminated with cathodes and separator sheets. Through-holes were formed in the anodes and cathodes. By contacting the anodes with Li metal which was attached beside the laminated cell, the pre-lithiation process to the graphite anodes was started. After pre-lithiation for a limited period of time, the pre-lithiated capacity was balancing among the pre-lithiated graphite by contacting among the anodes. The cells composed of through-holed anodes and cathodes were tested in charging/discharging cycle and removal of the irreversible capacity which can be observed at the first charging/discharging cycle was confirmed. The anodes which were treated with appropriate pre-lithiation charge and balancing period successfully could decrease irreversible capacity from 7 to 1% and the cells exhibited stable 100% of targeted capacity. In this study, practical pre-lithiation process to decrease the irreversible capacity could be proposed.

Fig. １ Schematic of a series of the process of perpendicular pre-doping, capacity balancing and charging/discharging examined in this study.