Lithium-Ion Batteries (LiBs) have become ubiquitous in modern technologies, such as in the burgeoning electric vehicle and consumer electronics markets. After manufacturing the LiB, a period of “break-in” occurs wherein the battery experiences rapid changes in properties, such as capacity [1] and stress [2], before leveling off to a stable value. Most research in LiBs analyze the full cycle life of the battery and have little regard for the initial break-in period. However, understanding and controlling break-in conditions could determine future performance of the cell. In this study, we use electrochemical acoustic and impedance spectroscopy measurements to analyze break-in of LiBs. We further analyze how break-in conditions, such as varying the rate of current, affect the overall performance of the battery.