Quantifying the Impact of Overdischarge on Large Format Lithium-ion Cells

摘要

Lithium-ion batteries can help enable the Navy and Marine Corps to meet their energy storage needs; however, safety is of paramount concern. Overdischarge, followed by recharge, is a failure mechanism in lithium-ion batteries that can be associated with long-term storage, poor battery module design, and internal cell defects. Overdischarge is known to cause copper dissolution, SEI layer degradation, and gas generation. By itself, overdischarge does not result in catastrophic thermal runaway; however, if a battery is recharged and used following an overdischarge event, the chances of thermal runaway increase. This paper describes an ongoing investigation into the link between depth and duration of overdischarge, quantitative changes to the cell as a result of overdischarge, and performance and safety characteristics in lithium-ion batteries. Through the use of x-ray photoelectron spectroscopy (XPS), we measure copper dissolution in both an overdischarged cell and a healthy cell.