Reliability and failure analysis of Lithium Ion batteries for electronic systems

This paper presents an investigation into the reliability and physical degradation mechanisms associated with the loss of battery performance. Cells from two different manufactures underwent cycle life testing until failure (defined as a 20% decrease in nominal capacity). Designated samples from each battery type were subjected to one of two different discharge methods, one at a constant discharge rate of 1C and the other at a constant discharge rate of 0.5C. A third group of batteries were collected and examined after undergoing catastrophic failure in field applications. The tape pull test (to test adhesion/cohesion of electrode material to current collectors) is introduced for the first time in battery literature. Other analysis techniques such as x-ray imaging and environmental scanning electron microscopy were used to investigate the structural and chemical degradation of all the samples. Statistical analysis was performed on the cycle life data to evaluate battery reliability.