Dynamically Stable and Intimately Bonded Li/Garnet Interface for High‐Areal‐Capacity Solid‐State Lithium‐Metal Batteries

Abstract A multifunctional Li 3 N‐Li 2 O hybrid interlayer is elaborately designed and constructed by a facile one‐step surface etching method to address the issues of lithium dendrite penetration and the interfacial Kirkendall voids formation in solid‐state lithium metal batteries based on garnet‐type electrolyte Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 . The constructed Li 3 N‐Li 2 O hybrid interlayer greatly promotes interfacial lithium‐ion conduction while dramatically reducing leakage of electronic current from the lithium anode to garnet by three orders of magnitude. Most importantly, the introduced Li 3 N‐Li 2 O interlayer shows a high interfacial work of adhesion with both garnet and Li, preventing detachment between the lithium metal and electrolytes during the lithium stripping process, even at high areal capacity cycling. Benefiting from such a synergistic effect, the assembled lithium symmetric cell exhibits a high critical current density of 2.6 mA cm −2 and achieves a stable cycling for over 100 h for an ultrahigh areal capacity of 4.0 mAh cm −2 at a current density of 0.4 mA cm −2 .