Thermal characteristic evolution of lithium–ion batteries during the whole lifecycle

Abstract

This work extensively investigates the thermal characteristic evolution of lithium-ion batteries under different degradation paths, and the evolution mechanism through multi-angle characterization is revealed. Under different degradation paths, the evolution trend of temperature rise rate remains unchanged with respect to depth of discharge during the adiabatic discharge process, albeit to varying degrees of alteration. The temperature rise rate changes significantly with aging during the adiabatic discharge process under low-temperature cycling and high-rate cycling paths. The total heat generation rate, irreversible heat generation rate, and reversible heat generation rate exhibit similar evolution behavior with aging under different degradation paths. The interval range of endothermic process of reversible electrochemical reactions increases and the contribution of irreversible heat to the total heat increases with aging. To further standardize the assessment of different degradation paths on the thermal characteristics, this work introduces the innovative concept of “Ampere-hour temperature rise”. In low-temperature cycling and high-rate cycling paths, the ampere-hour temperature rise increases significantly with aging, particularly accentuated with higher discharge rates. Conversely, in high-temperature cycling and high-temperature storage paths, the ampere-hour temperature rise remains relatively stable during the initial stages of aging, yet undergoes a notable increase in the later stages of aging. The multi-angle characterization reveals distinct thermal evolution behavior under different degradation paths primarily attributed to different behavior changes of severe side reactions, such as lithium plating. The findings provide crucial insights for the safe utilization and management of lithium–ion batteries throughout the whole lifecycle.