Lithium-Ion Battery Real-Time Diagnosis with Direct Current Impedance Spectroscopy

The health and safety of lithium-ion batteries are closely related to internal parameters. The rapid development of electric vehicles has boosted the demand for online battery diagnosis. As the most potential automotive battery diagnostic technology, AC impedance spectroscopy needs to face the problems of complex test environment and high system cost. Here, we propose a DC impedance spectroscopy (DCIS) method to achieve low-cost and high-precision diagnosis of automotive power batteries. According to the resistance-capacitance structure time constant, this method can detect the battery electrolyte resistance, the solid electrolyte interphase resistance and the charge transfer resistance by controlling the pulse time of the DC resistance measurement. Unlike AC impedance spectroscopy, DCIS does not rely on frequency domain impedance to obtain battery parameters. It is a time-domain impedance spectroscopy method that measures internal resistance through a time function. Through theoretical analysis and experimental data, the effectiveness of the DCIS method in battery diagnosis is verified. According to the characteristics of DCIS, we further propose a fast diagnostic method for power batteries. The working condition test results show that this method can be used to diagnose online battery life and safety.