| Abstrakt: |
Understanding the behavior of lithium plating at low temperatures is crucial for optimizing charging protocols, and assuring safe and durable use of lithium-ion batteries. In this work, the electrochemical model with lithium plating as the side reaction is adopted to explore the phenomena and mechanisms. The model is parameterized and validated through the measured OCV (open circuit voltage), the discharging curves at different C-rates and temperatures, and especially the amount of plated metallic lithium under various conditions detected with NMR (nuclear magnetic resonance). When a coin model cell is charged from 0% to 60% (-25°C), 80% (-25°C), and 80% SOC (-20°C) using 1.5 C current, the lithium plating ratios, defined as the ratio between the charge corresponding to lithium plating and the total charge, are 1.15%, 1.55% and 0.92% respectively. The model indicates that lithium plating could occur even at SOCs lower than 10%, before the lithium-ion concentration at the surface of graphite particles becomes saturated. This can be attributed to the larger activation energy of lithium-ion intercalation, compared to that of lithium plating, which reduces the surface potential below the plating potential. The model is also used to determine the operating limits and subsequently the fast and safe charging protocols. [ABSTRACT FROM AUTHOR] |
