Despite the huge expansion of electric vehicle sales in the market, customers are discouraged by the possible catastrophic consequences brought by the safety issues of lithium-ion batteries, such as internal short circuits, especially in crash scenarios. Herein, we reveal the quantitative relationship between the deformations of the battery and the internal short circuit. By in situ and ex situ observations and post mortem characterization of the component materials, we quantify the stress-driven internal short circuit and failure behavior of the component material. With the aid of a validated numerical computational model as well as the in situ characterization of the global-field temperature, we successfully identify the minor and major short circuits of the cells upon various mechanical abusive loadings. Finally, we establish the internal short circuit criteria for typical formats of batteries. This discovery also provides a fundamental understanding of both internal and external stress-driven short circuits in a much broader context.

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.