Pattern Investigation and Quantitative Analysis of Lithium Plating under Subzero Operation of Lithium-Ion Batteries

Safety hazards arising from lithium (Li) plating during the operation of lithium-ion batteries (LIBs) are a constant concern. Herein, this work explores the coaction of low temperatures and current rates (C rates) on Li plating in LIBs by electrochemical tests, material characterization, and numerical analysis. With a decrease in temperature and an increase in C rate, the battery charging process shifts from normal intercalation to Li plating and even ultimately fails at -20 °C and 0.5C. The morphology observations reveal the detailed growth process of individual plated Li through sand-like Li, whisker Li, dendritic Li, mossy Li, and finally bulk Li, as well as aggregated Li from sparse to dense. Through quantitative analysis, the dynamic pattern under long-term cycles is revealed. The low temperature and high C rate will lead to an increase in Li plating capacity and irreversibility, which are further deteriorated with the cycles. In addition, a critical condition of high Li plating and high reversibility at -10 °C and 0.2C is found, and further studies are needed to reveal the competition between kinetics and thermodynamics in the Li plating process. This work provides detailed information on the range and growth process of Li plating and quantifies Li plating, which can be used for practical Li plating prediction and regulation.