Effects of impact mass on dynamic mechanical responses and failure modes of square lithium-ion batteries under impact loading

Electric vehicles are prone to collision accidents during operation, and power lithium-ion batteries are inevitably subjected to impact, which leads to varying degrees of damage to the battery, and assessing the extent of this damage is crucial for the safe use of the battery. Based on the above background, the study was conducted on the influence of different impact masses on the dynamic impact response and failure behavior of square lithium-ion batteries. Firstly, in the quasi-static compression test, six different feed rates were used to test the extrusion of lithium-ion batteries. The test results show that the peak load required for lithium-ion batteries to reach hard short-circuit failure continues to decrease with the increment of feed rate. This indicates that the short-circuit failure load of lithium-ion batteries under quasi-static conditions is mainly determined by the feed rate. Then the hammer impact test, through the regulation of the quality of the punch and impact speed, the system simulates the lithium-ion battery may encounter a variety of impact conditions. Impact quality is an important factor in determining the degree of damage to lithium-ion batteries. Under the same impact energy, the damage of low-speed large mass impact on lithium-ion battery is significantly higher than that of high-speed low mass impact. At a constant impact energy, mass is the dominant factor in determining the degree of battery damage. If the impact mass is heavier, it will produce a larger impact load, which will cause more serious damage to the internal structure of the lithium-ion battery, leading to its functional damage or even failure. Conversely, if the impact mass is lighter, the impact force generated is relatively small, and the damage to the battery structure is correspondingly reduced. Therefore, the size of the impact mass directly affects the degree of damage to the lithium-ion battery, which is a key indicator for evaluating its safety performance and durability. The impact speed has a significant impact on the voltage drop of lithium-ion batteries after damage. Especially accelerating the occurrence of hard short circuits, further exacerbating the sharp drop in voltage. This characteristic makes the impact velocity as an important consideration for evaluating the voltage stability and overall safety performance of lithium-ion batteries after damage.