三元锂电池的过放电诱发内短路实验研究

Experimental study on overdischarge induced internal short circuit of NCM batteries

设计了针对电池过放电特性的测试方法,并研究在不同的过放电程度下电池的内短路程度变化规律。结果表明:对于本实验所采用的三元锂电池,其过放电特性具有较好的一致性,其中SOC一致性比电压一致性更好;内短路的严重程度与过放电深度呈现非线性增长的关系。当本实验所采用三元锂电池过放电至-18%至-20%的SOC时,将发生不可逆的严重内短路现象,电池将表现成为一个线性电阻;而在发生严重内短路前,充电后的电池存在一个自修复的过程。

A method was presented to reveal the characteristics of the overdischarged batteries.Different levels of the internal short circuit were compared at the different degrees of overdischarge.The experimental results indicate that for the same batch of the NCM batteries,the overdischarge characteristics of different battery cells are almost the same.The overdischarge characteristics of SOC consistency is better than that of voltage consistency.The relationship between the levels of overdischarge and the severity of the internal short circuit exhibits a nonlinear growth.The irreversible critical internal short circuit would happen when the NCM lithium batteries were overdischarge between-18%to-20%of the SOC,and the severe irreversible internal short circuit would occur,and the batteries would behave as a resistance.The NCM batteries would have self-healing process during charging before the serious internal short circuit.