Abstract
Recently, lithium-ion cell with large capacity that can be applicable for industrial usages such as backup batteries for power systems has been developed. The lithium-ion cells are expected to reduce the space of the back up battery system drastically. In the backup applications, long service life as well as cell safety is required. Therefore, to improve the safety of the cell, we have prepared a separator that has higher endurance-temperature than conventional polyolefm separator and evaluated the effect on the cell performance. Moreover, a cell structure that has a heat conductor inside the cell was proposed, and the effect of the heat conductor on the characteristics of the cell in overcharge was verified by using a lithium-ion cell with rated capacity of 40 Ah. As a result, it was confirmed that improvement of the endurance-temperature of separator and installation of the heat conductor was effective for the improvement of the safety of the lithium-ion cell.
