Investigating microstructure evolution of lithium metal during plating and stripping via operando X-ray tomographicmicroscopy
Li metal is considered as the most important negative electrode active material for Li-based batteries because of its high theoretical specific capacity of 3860mAh g-1, which is an order of magnitude higher than the currently used graphite, and by being the most electropositive metal. When coupled with high-capacity cathodes, either Li insertion materials or conversion chemistries, or applied in a solid-sate configuration, a leap in energy density can be obtained. The main challenge in the direct utilization of Li metal as anode is the formation of a mossy and dendritic morphology upon cycling manifested in a low Columbic efficiency and a continuous consumption of the electrolyte through parasitic side reactions, continuous growth of the solid electrolyte interphase (SEI) and irreversible capacity loss on the anode. These issues are a result of processes taking place both during charge (Li plating) and discharge (Li stripping), creating an unstable electrode structure.
In this work, we demonstrate the use of operando synchrotron XTM to capture the formation, growth, and dissolution of Li microstructures.