Coupling Effect of State-of-Charge and Strain Rate on the Mechanical Behavior of Electrodes of 21700 Lithium-Ion Battery

Abstract As an emerging type of high-density lithium-ion batteries (LIBs) for electric vehicles, 21700 cylindrical batteries may suffer inevitable mechanical vibrations, curbstone impact/penetration, and crash accidents, which probably induce internal short circuit (ISC), thermal runaway, and more catastrophic events such as fire/explosion. Therefore, exploring the mechanical behavior quantitively serves as a cornerstone for a better understanding of the safety behaviors of batteries. This paper focuses on the characterization of the tensile mechanical behavior of the electrodes under different state-of-charges (SOCs) coupled with strain rate effect. In the meantime, a numerical computation model is also established to provide a fundamental understanding of the electrode deformation. We discover that both anodes and cathodes are highly anisotropic at various electrochemical statuses, and strong strain rate dependency can be observed. Results provide an in-depth and systematic characterization of the mechanical behaviors of the electrodes and a powerful tool for the future design, evaluation, and manufacturing of safer batteries.