废旧三元动力电池电热特性的实验研究

Experimental study on electro-thermal characteristics of aged power batteries with ternary material

动力电池老化容易引发荷电状态不准、退役电池筛选困难以及热安全性等问题,限制了电动汽车及废旧电池梯次利用的发展。而研究高比能量电池的老化特性,对比分析多种环境、多种条件下废旧电池的电热性能变化有助于为解决上述问题提供理论依据,因此基于动力电池测试系统对其进行了实验研究与讨论。研究表明:电池随着循环次数增加,有效容量和能量逐渐衰减,能量效率逐渐降低,底部截面发生膨胀;随着电池老化程度的增加,其倍率性能、环境温度适应性均会变差,内阻、内阻温度敏感度明显增大;电池电性能的变化直接影响其热性能,电池的工作温度以及温升速率与新电池相比明显增加,新旧电池工作温度的差异在低温环境或高倍率放电的条件下更为严重。

The aging of power batteries is likely to cause problems such as inaccurate state of charge, difficult screening of retired batteries, and thermal safety, which limit the development of electric vehicles and the use of old batteries. Furthermore, it may offer theoretical foundation to solve the above problems by studying on the aging characteristics and analyze the variation of electro-thermal performance between fresh and aged batteries in a variety of environments or conditions by comparison. Therefore, it is researched and discussed based on the power battery test system through experiments. It is found that effective capacity, energy and energy efficiency reduces gradually as well as the increase of cycle numbers. Meanwhile, there is a slight swelling phenomenon accompanied by aging at the bottom section. The rate characteristics and the adaptability of ambient temperature become worse with the increase of aging degree. Moreover, the resistances and temperature sensitivity of resistances increase obviously. The variation of electrical performance affects its thermal performance directly so that working temperature and temperature gradient of battery increase obviously with comparison of fresh battery. The difference of working temperature between fresh and aged batteries is more serious especially for discharging under low ambient temperature or by high rate.