Mechanism of the dynamic behaviors and failure analysis of lithium-ion batteries under crushing based on stress wave theory

Although quasi-static responses of lithium-ion batteries has been studied by many researchers recently, the dynamic behaviors and its underlying mechanism under crushing are still not fully understood. In this paper, the stress wave theory is employed to analyze the dynamic behaviors of 18,650 lithium-ion batteries for the first time. A numerical model of the battery cell is established and validated by experiments, which is then used to study the dynamic response under crushing within a wide scope of crushing velocity (up to 45 m/s). Many different responses are found that differ from quasi-static cases, including the early short circuit before drop in force, the "rise-drop-plateau-rise" force-displacement curve, the velocity-dependent crack positions and so on, all of which can be well characterized by stress wave. It is interesting that the failure displacement and the short-circuit position of the battery depends on the range of crushing velocity, which is resulted from different dynamic failure mechanism in each velocity range. Accordingly, a velocity-dependent failure criterion is obtained. The results show that a more specific strategy is needed in the safety design of battery modules under various crushing velocities.