Abstract: This article focuses on a 50 Ah high-capacity NCM battery as the research object, using thermal runaway（TR） time as the standard for the combination of electric and thermal working conditions. By changing the initial SOC and charging rate of the battery, TR experiments were carried out under the combined effects of normal charging and local overheating in different scenarios. Changes of thermal and electric parameter characteristics such as TR time, combustion behavior, TR SOC, maximum surface temperature, temperature rise rate and voltage peak of the battery in different scenarios were analyzed in detail. The results show that under the combined effect of normal charging and thermal abuse, the higher the initial SOC of the battery, the higher the charging rate, and the shorter the TR time. The severity of TR is determined by the battery's TR SOC; When the battery is at a lower SOC, it will experience TR during charging, and the voltage will suddenly increase to over 10 V before TR and then suddenly drop to zero. When the battery is at a higher SOC, the difference between the combined effect and single abuse of TR is significantly reduced.

Key words: lithium-ion batteries, thermal runaway, normal charging, thermal abuse