In situ formation of Li₃N interlayer enhancing interfacial stability of solid-state lithium batteries

The uneven deposition of lithium ions has raised safety concerns related to the growth of lithium dendrites on the surface of lithium metal batteries. In this work, an in situ formed Li₃N interlayer is introduced to regulate the deposition of lithium ions on the lithium metal surface effectively. The Li₃N interlayer is formed on the lithium metal surface by the reaction of nitrogen gas (N₂) released from the reaction layer at a specific temperature. The in situ Li₃N interlayer enables the Li||Li symmetric cell exhibits cycling stability over 1200 h at 0.2 mA cm^-2 due to the lower nucleation overpotential, demonstrating excellent Li plating/stripping performance. Furthermore, density function theory (DFT) calculations reveal that Li⁺ preferentially adsorb onto the Li₃N (001) plane and diffuse along the surface during the Li⁺ migration process. This in situ Li₃N interlayer effectively inhibits dendrite growth and the occurrence of side reactions, enabling stable cycling of Li||LiFePO₄ cell for over 700 cycles at 0.5 C. Additionally, Li||LiCoO₂ full cell also exhibits a capacity retention of 81.6 % after 500 cycles with a specific discharge capacity of 80.8 mAh/g and a coulombic efficiency (CE) of 99.4 %. This modification strategy is an effective approach for enhancing interfacial stability of solid-state lithium batteries.