Characteristics of Thermal Runaway Generation of Pouch-type Lithium-ion Batteries by Overcharging

Abstract

This study analyzes thermal runaway (TR) characteristics via experiments conducted on lithium-ion batteries. To generate the TR of lithium-ion batteries, overcharge was applied as an electrical abuse condition. The TR experiment was conducted in a chamber with the dimensions of 1.5 × 1.5 × 1.5 m by classifying the capacity of a pouch-type lithium-ion battery and cathode material employed. The experimental results demonstrated that the lithium-ion battery before TR exhibited repetitive voltage and temperature characteristics, and that TR could be detected in advance based on these characteristics. TR occurred after the cell surface temperature of the lithium ion battery was maintained at approximately 100 ℃ for a certain duration. The voltage of the lithium-ion battery gradually increased before TR; however, the voltage decreased after the inflection point (Vmax) was crossed. Then, the voltage increased sharply after decreasing for a certain duration and was higher than the voltage increase rate (V/min) observed before the inflection point (Vmax) was attained.