Effects of Electrolyte, State of Charge, and Strain Rate on the Mechanical Properties of Lithium-Ion Battery Electrodes and Separators

Abstract

The mechanical properties of electrode materials are critical to the mechanical, electrical, and thermal performance, safety, and durability of lithium-ion batteries (LIBs). While mechanical testing is often conducted to elucidate the fundamental behavior of electrode materials, most existing studies focus on dry electrodes, which fail to fully capture the in-cell conditions. To address this gap, this study provides a comprehensive investigation of the coupled effects of SOC, electrolyte, and strain rate on the mechanical behavior of cathodes and anodes through compression and tensile testing. The study begins by isolating the impacts of SOC and electrolyte individually, followed by an analysis of their coupling effects. Scanning electron microscopy (SEM) characterization under diverse conditions is employed to uncover the underlying mechanisms driving these behaviors. Results reveal that the interplay between SOC, electrolyte presence, and strain rate significantly influences the mechanical responses of electrodes. These findings offer critical insights into the behavior of battery components under realistic loading conditions, demonstrating the complexity of the coupling of solid-liquid interactions in porous materials, and providing a foundation for improving the evaluation and design of LIB safety and durability.