锂离子蓄电池高倍率放电研究

Study on discharge of Li-ion battery at high-rate

锂离子蓄电池在放电过程中电压随放电容量的增大而降低,电池的放电容量随放电电流的增大而减小。然而在高倍率放电的条件下,电池的放电电压曲线会出现电压峰,同时电池的放电容量也有所增大。通过红外热成像的方法对锂离子蓄电池高倍率放电条件下的热行为进行比较细致的研究表明:锂离子蓄电池放电过程中各个区域的电极反应是非常不平衡的;高倍率放电的条件下,开始时电池极耳附近区域的电阻较小,电流密度较大,因此这部分产生的热量比较大,温度升高较快;在放电过程的后期,靠近极耳区域的容量耗尽,远离极耳区域的部分如果温度上升比较缓慢时,会导致放电过程终止,反之会出现电压上升的现象。该研究为锂离子蓄电池特别是锂离子动力电池的设计提供了新的思路。

The voltage of Liion battery was decreased with the increase of discharge capacity while its discharge capacity was decreased with the increase of discharge current. However, when the battery was discharged at high rate, the voltage peak would be in the curve of discharge voltage and the discharge capacity would also be increased. The results of research by IR Thermal Imaging systems show that when Liion battery is discharged at high rate, the electrode reaction in each part is not equilibrium. At the beginning of highrate discharge, the resistance closed to tabs is low and the current density there is high, so this part has large heat and the temperature is elevated quickly. At the end of discharge process, the energy around the tabs is consumed away. At that time, if the temperature of the part far from the tabs increases slow, the discharge process is terminated prematurely. The study provides new way for designing Liion battery, especially the power battery.