The charging/discharging characteristics of lithium-ion battery are mainly dependent on itself temperature which is determined by the balance both the heat generated by battery itself and the heat removed by the battery thermal management system (BTMS). Consequently, study on the heat generation behaviors of the lithium-ion battery is necessary for designing the BTMS which is capable of maintaining batteries at optimum temperature ranging from 20℃ to 40℃. In this study, the heat generation behaviors and electro-thermal characteristics of a prismatic LiFePO4 battery with a high nominal capacity of 280Ah at the charging rates of 0.5C and 1C and initial temperatures of 15℃, 25℃ and 35℃ were comprehensively explored using an electrochemical-calorimetric method. The experimental results show that the charging capacity at the end of charging is nearly independent on the above mentioned charging rates and initial temperatures, which is due to the positive effect of heat generated by the battery itself in accelerate calorimeter rate (ARC). However, it is noted that the heat generation rates during the charging process (especially for the beginning of charging) significantly increases with the growth of charging rate and the decrease of initial temperature. At the state of charge (SOC) equal to 0.1 and initial temperature of 15℃, the heat generation rates at charging rates of 0.5C and 1C are about 20.2 W and 76.6 W respectively, that is to say, the heat generation rate at high charging rate of 1C is nearly 3.8 times than that at moderate charging rate of 0.5C. These findings indicate that the battery own the excellent charging efficiency (short charging time and charging capacity nearly equal to nominal capacity) at the high charging rate of 1C, however, significant rise of heat generation rate inevitably brings the huge challenge for the BTMS. This study may also provide some guidance for the design of BTMS.
Keywords lithium-ion battery, heat generation behaviors, electro-thermal characteristics, electrochemical-calorimetric method