LAUSR

Abstract The internal temperature of the battery is important for the design of battery thermal management and battery safety; however, it is difficult to be tested and seldom studied. A method of embedding thermocouples inside a prismatic L i [ N i 1 / 3 C o 1 / 3 M n 1 / 3 ] O 2 (NCM) lithium-ion battery was developed to study the temperature inconsistency between the battery interior and the surface. Six thermocouples were embedded in the interior and six were attached to the surface of the battery. First, the feasibility of the embedding-thermocouples method was verified by comparing the capacity, resistance, temperature etc. between the batteries with and without embedded thermocouples. Then 1C and 2C charging and discharging experiments were carried out under the adiabatic condition in an Accelerating Rate Calorimeter (ARC). 1C−5C rates of charging and discharging experiments were executed under the natural convection condition. The temporal and spatial temperature varieties of battery interior and surface were analyzed. The experimental results show that under the adiabatic condition, the temperature difference (TD) between the interior and surface of the battery was small, only 1.7 °C at 1C discharge rate and 3.1 °C at 2C discharge rate. However, under the natural convection condition, the maximum TD reached 11.3 °C at 5C discharge rate. The TD among the six internal temperature measurement points was small for all cases, which means a good uniform temperature distribution inside the battery. In addition, through experiment-data analysis, a near linear relationship was found for the battery internal and external temperature. The effect of the current rates on the maximum temperature and the maximum temperature difference was also studied. The results showed that a good quadratic function relationship was observed for both the maximum temperature and the maximum TD.