Lithium-Ion Battery Online Capacity Diving Multilevel Evaluation and Early Warning Method Based on State of Nonlinear Aging

As an effective way to energy conservation and emission reduction, lithium-ion batteries (LIBs) have been widely used in energy storage, electric vehicles, 3C devices, and other related fields, and will have greater application prospects in the future. However, the aging failure of LIBs with nonlinear features, especially the capacity diving, will not only cause a sudden drop in capacity, but also damage the safety of LIBs and lead to thermal runaway. In this paper, a nonlinear evaluation indicator, state of nonlinear aging (SoNA), is introduced to quantify the capacity diving degree of such nonlinear aging batteries, and a multi-level evaluation and early warning method for capacity diving is established. Through this evaluation and early warning method, the severity of the capacity diving behavior can be identified, so as to remind the user whether to replace or maintain the battery, which greatly reduces the risk of battery safety issues.