本研究是應用交流阻抗技術，以主動線上偵測方法對鋰離子電池進行殘餘容量偵測。交流阻抗技術能夠有效的評估電池的殘餘容量，包含動態範圍及靜態範圍下之量測。本研究運用恒電位方式對電池進行主動偵測，交流振幅大小為10mV，阻抗分析的頻率範圍為1Hz-10kHz，並應用奈氏圖來分析所量測之結果，奈氏圖為實部阻抗相對於虛部阻抗之圖形。實驗結果得知，動態量測及靜態量測之奈氏圖會有所不同，主要是因為電池內部電化學反應所引起的交流阻抗也有所不同，而放電過程中，當殘餘容量越來越小時，經由交流阻抗所呈現之奈氏圖也會有所改變，故本研究能經由主動線上偵測的方式，利用鋰離子電池的交流阻抗特性，來估算出鋰離子電池在動態範圍及靜態範圍下之殘餘容量。

An AC impedance-based technique for active online measurements of Li-ion battery systems is developed in this paper. An AC impedance technique is proposed to estimate state of charge (SOC) for Li -ion battery. The technique includes a set of static and dynamic measurements that are required for state of charge estimation. In this paper, potentiostatic measurements of Li-ion batteries, AC signal amplitude of 10mV is used. The impedance spectra are measured by sweeping frequencies between 1Hz and 10 kHz with 6 points/decade. The measurement results are presented in a Nyquist plot, a plot of real impedance against imaginary impedance. The test results shows that Nyquist plot of dynamic and static measurement of a battery cell are different, due to the internal electrochemical response. This is caused by the AC impedance that are different at frequencies. In discharge process, when SOC of cell is dropped, its AC impedance is also changed. Therefore, through active online detection, the proposed AC impedance technique can be utilized to measure the SOC of Li-ion battery.