A Mixed Modified Layer Formed in Situ to Protect and Guide Lithium Plating/Stripping Behavior

Uncontrolled lithium (Li) plating/stripping is one of the most fatal problems of lithium metal batteries (LMBs). Herein, we modified a copper (Cu) foil current collector surface with an indium nitride (InN) thin film, which regulated the Li plating/stripping process through in situ lithiation. That is, InN transformed into a lithium nitride (Li3N)/Li-In alloy phase (LixIny)-mixed protection layer during the first Li plating process. Li3N is an efficient Li+ conductor and is stable to Li, whereas LixIny possesses fast Li+ diffusion kinetics. The synergistic effect of these two species simultaneously caused the mixed protective layer to display fast Li+ diffusion, inhibited the rapid growth of Li dendrites, and induced bottom Li deposition under the protective layer. Li∥Cu cells exhibited higher Coulombic efficiency and a more stable lithium plating/stripping process than a control cell without an InN layer. Moreover, when an InN thin film was transplanted onto the surface of a Li metal sheet using the same method, the resulting Li∥Li symmetrical cell delivered extraordinary performance. This in situ formation of a multifunctional modified layer by a facile preparation process could be an effective way to inhibit dendrite growth and accelerate the application of LMBs.