Tracing the Thermodynamic Footprint of Aging in Lithium-Ion Batteries

Lithium-ion batteries (LIBs) are indispensable for powering modern devices and renewable energy systems, yet aging and degradation processes significantly challenge their longevity and performance. This study uncovers a novel phenomenon termed the "aging memory effect," in which LIBs retain a thermodynamic trace of their aging history. Our findings illuminate the intricate relationship between battery aging and thermodynamic behavior, offering a fresh perspective for diagnosing and mitigating degradation.

Entropy measurements revealed variations in the degree of disorder within the electrodes, while enthalpy data captured the energy associated with phase transformations. These thermodynamic parameters provide critical insights into the battery's aging and degradation pathways.

The ability to retrace a battery’s aging memory through ΔS and ΔH measurements has profound implications. It enables identifying the electrode primarily responsible for limiting the battery’s capacity and provides a detailed understanding of the degradation mechanisms at play. This diagnostic approach bridges the gap between thermodynamic properties and electrochemical performance, offering a deeper understanding of internal dynamics within aged cells.

Furthermore, this thermodynamic analysis can inform predictive models for battery aging, enhancing the accuracy of state-of-health (SOH) and remaining useful life (RUL) estimations.