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This paper proposes a highly effective voltage cell equalization method for lithium-ion (Li-ion) battery management systems (BMSs) for several applications, such as nearly zero energy buildings, microgrids, and electric vehicles. The concept of the suggested method is the proper control of the charging current of each cell of a battery stack through the suitable regulation of the gate source of each cell's parallel-connected mosfet. Thus, the mosfet can act as a controllable current source for providing the proper equalization current according to the specific needs of each battery cell. The correct voltage level of the gate-source of each mosfet is determined by a cell equalization controller through the comparison of the performance of each cell of a battery stack with the healthier cell, which is detected by an aging estimation algorithm based on the evaluation of the internal resistor and the capacity fade of each cell. Therefore, smoother and faster cell equalization is achieved compared to the conventional dissipative method. The practicality and the high effectiveness of the proposed cell equalization technique have been experimentally validated. Several experimental results are presented to demonstrate the operational improvements of the proposed cell equalization technique against the conventional one. [ABSTRACT FROM AUTHOR]

This paper proposes a lithium plating detection method for lithium-ion batteries that can be applied in real time, during the charging procedure. It is based on the impedance analysis and it can be realized by utilizing the dynamic electrochemical impedance spectroscopy (DEIS) technique. Specifically, a sinusoidal current is superimposed on the charging current, and the battery impedance is analyzed in the frequency domain without interrupting the charging procedure. In case of lithium plating during charging, the graphite interfacial impedance is significantly decreased and thus, the lithium plating can be detected by monitoring the real and imaginary parts of the battery impedance in real-time. Two battery cell types with different active materials and energy densities are examined at several temperatures and charging currents. The effectiveness of the proposed DEIS technique is validated with the voltage relaxation profile method and in comparison with the current interruption method, for different charging conditions, cell formats and chemistries. The experimental results reveal that the proposed method is capable to effectively detect the lithium plating for rates as high as 6C, at different temperatures and for different battery types. • Nondestructive method to detect the onset of lithium plating during charging • Dynamic EIS applied in real-time without interrupting the charging procedure • Lithium plating is detected by monitoring the battery interfacial impedance • Battery operating conditions are considered at the lithium plating detection • Experimental validation and correlation with existing methods [ABSTRACT FROM AUTHOR]