Early Warning Strategy for Thermal Runaway of Lithium-Ion Battery Packs

Lithium-ion batteries have a series of advantages such as high specific energy, light weight, environmental protection and safety, no memory effect, and stable performance. The thermal runaway of lithium-ion batteries is a potential safety hazard of lithium-ion battery packs. The internal short circuit of lithium-ion batteries is a common link in the thermal runaway of batteries caused by mechanical abuse, electrical abuse, and thermal abuse. How to identify the internal short-circuit battery in the latent period before thermal runaway occurs becomes a difficult problem. This paper proposes an internal short-circuit detection method for lithium-ion batteries based on the remaining charge capacity. The main mechanism of this method is to realize the internal short-circuit detection through the inconsistency between the short-circuit battery in the battery pack and the remaining charge capacity of the normal battery. Under constant current charging, the battery power increases linearly, and the remaining charging power of the short-circuit battery can be obtained by multiplying the charging time difference between two adjacent charging conditions by the charging current, and the short-circuit current can be calculated and converted into short circuit resistance. This method can not only detect and determine the internal short-circuit battery in the lithium-ion battery pack, but also quantitatively calculate the short-circuit resistance value and leakage current. It can be seen from the experimental results that the error between the theoretical and experimental results of the internal short-circuit resistance is within 10%.