电化学阻抗谱法预测锂电池荷电状态

SOC of lithium-ion rechargeable battery predicted by electrochemical impedance spectroscopy

为了准确预测使用过程中的电池荷电状态,提出了电化学阻抗谱预测法。通过试验曲线得知电池的阻抗图谱包含一个高频区的感抗弧和两个低频区的容抗弧,由此建立了锂电池合理的等效电路,并通过非线性拟合的最小二乘法和电化学知识相结合,解析了等效电路中的元件参数值。研究各参数随荷电状态变化的规律,发现阻抗模的最大值处的频率fmax、相角参数Φ以及等效电容CS可用于锂电池荷电状态的分析和预测。

For predicting the state of charge（SOC） of lithium-ion rechargeable battery accurately, a method based on electrochemical impedance spectroscopy was presented. The test curves show that dispersion of impedance data are comprised by an inductive part in the high-frequency region and two capacitive parts in the low-frequency region. The reasonable equivalent circuit of battery was established. The data obtained at several state of charge values of the battery were analyzed by a non-linear least-squares fitting procedure and some electrochemical knowledge. The frequency of maximum of the semicircle （fmax）, the phase angle Φ, the equivalent series capacitance （Cs） were identified as suitable parameters for predicting the state of charge values of the lithium-ion battery.