Operando safety diagnosis for Li-ion battery via MHz band electromagnetics

A nondestructive, simple detecting method of internal Li-metal plating in the Lithium-ion battery (LiB) is essential for diagnosing the safety of battery systems for realising the long-life use of the LiB. We show a direct Li-metal detection technology that is dependent on the electromagnetic response of the battery at a high-frequency (MHz). By the unique response of the high-frequency electromagnetics based on the Maxwell’s law, a negative correlation is observed between the real-part impedance and the internal Li-metal plating deposited on the anode surface by the partial electrochemical potential overstress. This finding makes the diagnostic process much simpler than conventional methods such as data-driven analytical approach, because this finding measures a direct response from the electronic behaves to the metal deposition, rather than symptoms from the ionic behaves. The sufficient decrease in the real-part impedance was confirmed only in the Li-metal plated commercial batteries (LFP-18650, 1500 mAh, representatively) that are degraded by repeated rapid charging. Notably, this finding can be assembled as a battery monitoring sensor that diagnoses the growth of Li-metal plating during real-field operation. This finding is expected to contribute to the solutions for the new global environmental challenges by supporting the safe and long-term use of LiBs both in the classification process and its reuse.