基于不同衰退路径下的锂离子动力电池低温应力差异性

锂离子动力电池受到的低温冲击通常发生在某一特定情况下,其低温应力与新电池存在一定差异。通过以35A·h复合材料电池为研究对象,针对电池充放电过程中存在的不同反应阶段,利用转化容量增量曲线划分电池工作区间,使电池在不同SOC区间循环老化,跟踪其电化学特性变化,分析衰退机理。在0℃环境下,采用C/3、C、3C/2、2C和5C/2电流依次对老化电池进行充放电冲击,分析基于不同衰退路径下的动力电池低温应力差异性。结果表明:动力电池在不同SOC区间循环使用会产生差异性明显的衰退路径,其低温衰退与其之前经历的循环衰退并不存在映射关系和一致性。同时得到的结论为动力电池成组应用的寿命分析和梯次利用电池的筛选配组提供依据。

The Lithium-Ion Battery Low Temperature Stress Based on Different Degradation Paths

Lithium power battery is usually impacted by low temperature in a particular situation, and its low temperature stress is different with that in initial condition. Taken 35 Ah composite battery as an example, work range of the battery was divided by the transformation curve of the incremental capacity analysis based on different reaction stages of battery charging and discharging process. By aging the batteries at different SOC range, this paper traced the changes of electrochemical properties and analyzed degradation mechanism. Under 0℃ environment, the stress differences under low temperature of batteries which were degraded through different paths, was analyzed usingC/3, 1C, 3C/2, 2C and 5C/2 currents to impact the aging cells by charging and discharging respectively. The result showed that the power battery produced obviously different degradation paths when it cycled at different SOC ranges. There is no mapping relation and consistency between low temperature degradation and cycling degradation. The conclusion provides the basis for battery pack lifetime analysis and second battery matching.