The influence of local lithium plating on battery safety and a novel detection method

Li-ion batteries are widely used in the clean energy field, but battery safety is an unresolved obstacle. Spontaneous accidents are difficult to prevent and are usually thought to be related to internal failures in the battery. Among various failure modes, the mechanism and detection method of local lithium plating are still challenging. In this study, an anode crack defect is implanted in the battery to reproduce the failure mode of local lithium plating accurately. The effects of local lithium plating are revealed by electrochemical testing, disassembly characterization, and thermal testing. The plated lithium is porous and contains a large percentage of irreversible lithium in the metallic state. After being fully infiltrated by the electrolyte, metallic lithium can degrade the thermal stability of the battery. The local lithium plating can produce a similar risk as homogeneous lithium plating but is more difficult to detect. As the inhomogeneous Li-ion distribution leads to persistent Li-ion exchange, this study proposes a relaxation voltage-based detection method. The detection method is well-targeted for the local lithium plating problem and significantly outperforms existing detection methods for homogeneous lithium plating. The mechanism and method proposed in this study can guide the design of future battery safety management strategies.