Operando Li metal plating diagnostics via MHz band electromagnetics.

A nondestructive detection method for internal Li-metal plating in lithium-ion batteries is essential to improve their lifetime. Here, we demonstrate a direct Li-metal detection technology that focuses on electromagnetic behaviour. Through an interdisciplinary approach combining the ionic behaviour of electrochemical reactions at the negative electrode and the electromagnetic behaviour of electrons based on Maxwell's equations, we find that internal Li-metal plating can be detected by the decrease in real part of the impedance at high-frequency.

Impact of Surface Layer Formation during Cycling on the Thermal Stability of the LiNiCoMnO Cathode.

In this study, the effects of charge/discharge cycling on the thermal stability of LiNiCoMnO, a high-Ni cathode material, are systematically investigated. X-ray diffraction measurements show that there is almost no change in the bulk structure of the cathode after cycling. However, X-ray absorption fine structure measurements indicate that Ni in the surface layer is reduced and stable rock-salt structures are formed.