基于库仑效率的退役锂离子动力电池储能梯次利用筛选

The Reutilization Screening of Retired Electric Vehicle Lithium-Ion Battery Based on Coulombic Efficiency

用于电动汽车的锂离子动力电池退役后,具备在储能系统等场合继续使用的潜力,其健康状态的准确预测对于退役电池的梯次利用具有重要意义。考虑到目前采用的电池性能预测指标估算精度上的不足,本文从电化学角度出发,分析库仑效率与电池容量衰减之间的内在关系。针对锂离子电池充放电循环中可逆锂源的消耗机理,在库仑效率的基础上引入了库仑非效率的定义。在相同实验条件下分别获得两块退役锂离子动力电池充放电容量、库仑效率、库仑非效率三者与循环次数之间的关系。最后,在库仑非效率测试结果对比中,创造性地采用对数坐标系,就此提出基于库仑效率对退役锂离子动力电池储能梯次利用进行筛选的方法,并通过实验验证了该方法的正确性。

Retired Lithium-ion batteries in electric vehicles have the potential to reuse in other energy storage systems. The accurate prediction of state of health (SOH) is of great significance. For better and quick screening healthy batteries for reutilization from numerous retired cells, this paper has come up with a screening method based on coulombic efficiency. Firstly the intrinsic electrochemical relationship between battery coulombic efficiency and capacity attenuation was analyzed. According to the consumption mechanism of reversible lithium ions during the charge-discharge cycles, coulombic inefficiency was introduced as a screening factor based on coulombic efficiency. The relationship between charge and discharge capacity, coulombic efficiency, and coulombic inefficiency with cycle times of two retired batteries (healthy and unhealthy) was obtained under same experimental conditions. The results demonstrate that healthy battery can be accurately screened out by coulombic inefficiency in logarithmic coordinate system, and this method was verified by cycle life test.