Effect of Overdischarge on Swelling and Recharge Performance of Lithium Ion Cells

Abstract Effects of overdischarge on characteristics of lithium ion cells were deeply studied, and experiments have been made to reveal its mechanisms. The results suggest that overdischarge may result in large swelling of cells and degradation of recharge capabilities. The mechanism can be explained as that: a copper foil used as an anode collector will be oxidized to copper ion when deep overdischarge occurs and reduce at the anode in recharging progress, which greatly deteriorates the cell efficiency; solid electrolyte interface (SEI) film is to decompose and reform because of excessive de‐intercalation of lithium ions, and the released gas such as carbon dioxide makes the cell bulge. The experimental results prove that when 20% Li(Ni 1/3 Co 1/3 Mn 1/3 )O 2 was added to LiCoO 2 cathode materials, the cell swelling rate could be greatly reduced, and the recharge capability would be enhanced much.