具有磷酸铁锂电池负极特征的SOC区间的确定方法

A Method to Determine Characteristic Region of Negative Electrode with State of Charge for Lithium-Ion Battery

商用锂离子电池包含正极和负极,这两个电极的老化速度一般不一致。以磷酸铁锂电池为例,该电池老化主要由负极贡献的。为了在不拆解全电池的情况下研究其老化问题,需要从其外特性中求取可反映老化现象的负极特征曲线,然后再从这段特征曲线中确定相关的老化信息。该项工作首先需要确定该曲线明显的荷电状态(SOC)区间段,称为负极特征区间。为此,该文首先提出电池基于分数阶模型的线性化电势变化模型;通过研究在不同SOC工作点处正负电极电势的变化特征,给出可以利用全电池阶跃电流激励仿真确定该负极特征区间的方法;最后分析了该区间与电池老化的关联性。该文采用三电极电池(含参比电极)验证了该负极特征区间的正确性,该方法对商用磷酸铁锂电池老化问题的在线观测具有指导意义。

There are a positive and a negative electrode in a commercial lithium ion batteries.The aging rates of the two electrodes are generally inconsistent.Take lithium iron phosphate batteries as an example,the negative electrode dominates the degradation in this battery.It is considerable to distinguish the characteristics of the negative electrode from the external characteristics of the battery,and then to find the relevant aging information from this characteristic curve to study the aging problem of lithium iron phosphate batteries without dismantling them.As first step of the work,It is necessary to determine the obvious characteristics’SOC region of the curve which is called negative characteristic region in this paper.Based on the fractional-order model and the linear model of different State of charge(SOC)working point,this paper analyzes potential change of two electrodes under different SOC,and give a method to determine the negative characteristic region.Finally,the correlation between the region and the aging of the battery were analyzed.These results are verified by the three-electrode experiment,which indicates that this method has guiding significance for the on-line observation of the aging problem of commercial lithium iron phosphate battery.