Abstract: In order to study the thermal runaway risk of ternary lithium batteries, 18650 nickel cobalt manganese ternary lithium batteries were selected as the research object, and a testing platform for measuring the characteristic parameters of battery thermal runaway process was built to explore the thermal runaway process and combustion trace characteristics of lithium-ion batteries under different states of charge, electrical abuse, and thermal abuse. The results show that the positive current collector plate of lithium batteries has a certain protective effect on thermal runaway caused by overcharging and short circuit of the battery. When the SOC is above 25%, the degree of thermal runaway damage to the battery is directly proportional to the charge. By combining the characteristics of voltage and temperature changes before and after thermal runaway in lithium-ion batteries, as well as the characteristics of battery explosion and combustion, the characteristic peaks of the temperature curve can be used to determine the state of the battery that has experienced thermal runaway, and X-ray and voltage changes can be combined to determine the fault state of the battery and trace the location of the fire in the lithium-ion battery. The research results can provide reference basis for lithium battery design, lithium battery fire extinguishing, and fire investigation.

Key words: nickel cobalt manganese ternary lithium battery, overcharging, thermal runaway, temperature, burning marks