A comprehensive heat generation study of lithium titanate oxide-based lithium-ion batteries

A precise interpretation of lithium-ion battery (LIB) heat generation is indispensable to the advancement and accomplishment of thermal management systems for different applications of LIB, including electric vehicles. The internal resistance of a lithium titanate oxide (LTO)-based LIB was determined at different state of charge (SOC) levels and current rates to understand the relationship between internal resistance and heat generation. Random and different pulse discharge current step durations were applied to consider the effect of different SOC interval levels on heat generation. The total generated heat was measured for different discharge rates and operating temperatures in a Netzsch IBC 284 calorimeter. It was seen that a 6.7% SOC decrease at high SOC levels corresponds to 0.377 Wh, 0.728 Wh, and 1.002 Wh heat generation for 26A, 52A, and 78A step discharge, both at 20 °C and 30 °C. However, a 1.85% SOC decrease at medium SOC levels corresponds already to 0.57 Wh, 0.76 Wh, and 0.62 Wh heat generation. It can be inferred that the impact of SOC level on heat generation for this cell is more prominent at a lower than at a higher SOC.