Numerical Modeling of Asymmetric-Temperature Cycling for Lithium-Ion Batteries Under Fast-Charging Conditions

High temperatures during charge–discharge cycles pose a significant threat to the safety and capacity of lithium-ion batteries by accelerating solid–electrolyte interphase (SEI) growth. Conversely, elevating the temperature during charging enhances Li-ion transport and suppresses lithium plating, suggesting an asymmetric temperature modulation (ATM) strategy in which cells are charged at elevated temperatures and discharged at room temperature to mitigate degradation under extreme fast-charging conditions. In this study, a one-dimensional electrochemical model incorporating key side reactions—SEI formation, lithium plating, and lithium stripping—is developed to analyse the ageing behaviour of plug-in hybrid electric vehicle (PHEV) cells under ATM operation. Within the present modelling framework and for the investigated temperature and current ranges, lithium plating is found to exert only a modest influence on the SEI growth rate, and the capacity degradation associated with SEI formation at a given temperature follows a unique time dependence that shows only a weak sensitivity to the charging rate. A phenomenological hill-shaped dependence of plating reversibility on the state of charge (SOC) is implemented based on experimental observations. The simulation results show good agreement with experimental data for PHEV cells operated under ATM, reproducing a capacity retention of about 80% after 1000 cycles at a charging temperature of 49 °C.