Abstract:

Thermal runaway of battery is an irreversible failure mode that can, in its most severe form, cause battery combustion and explosion, which can trigger the combustion of electrical vehicles, resulting in heavy loss of property and danger to human life. Therefore, it is considerably significant to study thermal runaway for understanding the failure mechanisms of the Li-ion batteries and improving the battery quality by optimizing the design to reduce the risk of battery combustion and explosion. Based on the electrical vehicle incident investigations, thermal runaway can be mainly attributed to mechanical abuse. In this study, the research progress with respect to the effects of nail penetration and crushing on the thermal runaway of the Li-ion vehicle batteries is summarized. In additional, the factors that influence the thermal runaway of Li-ion batteries are systematically analyzed, including battery materials and structures. Results show that under nail penetration and crushing, the battery charge states, internal structural design, and chemical systems considerably influence the thermal runaway results. Among them, the internal structural design and chemical systems of the batteries affect their thermal safety performance. Furthermore, mechanical abuses, such as nail penetration and crushing, trigger thermal runaway by causing large-scale internal short circuits in the batteries. Hence, rationalization proposals with respect to battery safety design have been proposed based on the related research results to avoid internal short circuits.

Key words: battery safety, thermal runaway, mechanical abuse, lithium ion battery