Changes in Thermal Stability of Cyclic Aged Commercial Lithium-Ion Cells

Abstract

Thermal stability is one of several factors affecting the safety properties of lithium-ion cells. The thermal stability for uncycled cells is well-documented, but the effect of cyclic ageing on thermal stability is far less studied and only for 18650 sized cells. In this paper, we describe how different temperature and current loads are affecting the thermal stability during cyclic aging. Three cylindrical lithium-ion power cells with different cathode, energy content and size were cyclic aged. Decrease in thermal stability was found in all three cyclic ageing test series as a function of relatively high current and low temperature. The decrease in thermal stability could be dangerous and should be an end of life criterion.