Experimental research on the thermal runaway of lithium-iron-phosphate batteries under high-speed impact condition

Abstract With the rapid development of the new energy vehicle industry, the safety of power lithium-iron batteries has garnered significant attention. In this article, a 50 Ah square lithium-iron phosphate battery is used as the research object for a high-speed impact test. Through the self-designed high-speed impact test device of the lithium-ion battery, the piston is powered by high-pressure gas to impact the 50 Ah square lithium-iron phosphate battery, and the gas pressure is changed to simulate the impact of different speeds on the battery. We analyze the electric heating response of the battery under different impact conditions, study the impact speed, impact depth, punch shape, and state of charge on the impact safety of the battery, using the battery voltage and temperature changes after impact to describe the thermal runaway risk of the battery. The results show that the higher the impact velocity and the deeper the impact depth do not necessarily lead to a greater risk. There is a critical impact velocity and critical impact depth that make the risk of thermal runaway of the impact greatest. When the spherical punch hits the battery, the larger the punch diameter is, the faster the battery temperature rises and the higher the peak temperature is. When the sharp object destroys the battery, it is easier to cause thermal runaway, and the risk of thermal runaway is greater. With the increase of the battery’s state of charge, the risk of battery thermal runaway increases. This study supplemented research on the different factors affecting the thermal runaway risk of lithium-iron-phosphate batteries under the condition of high-speed impact and provided effective support for the safety research of lithium-iron-phosphate batteries.