Overcharge Tolerance of Intercalation Compounds in Lithium-ion Batteries

The tremendous success of lithium-ion battery technology is evident from its commercialization into a market dominating position and its enabling wide spread use of sophisticated portable powered technology. However, public awareness of lithium-ion technology safety has increased through recent laptop computer and cell phone recalls. Safety concerns are also one of the major hurdles to introduction of Li-ion cells into new large-format transportation applications (i.e., PHEVs and EVs). Charging protocols have been implicated in some of the small-cell field failures. One critical failure mode, overcharge, can arise through inappropriate selection of battery management parameters (i.e., voltage limits), poor charge voltage control tolerances for cells within a pack, and inaccuracies in the charging circuitry in either the battery pack or electronic device. Increasing demands for run-time and energy density in combination with cost pressures have influenced both electronic designers and cell manufacturers to increase charge voltage limits to maximize cell capacity. Without proper considerations, higher voltage limits can disrupt the lithium-ion system and its market acceptance. Overcharge tolerance of intercalation compounds will be discussed in the context of these market factors for Li-ion applications from a systems perspective.