Nanotrench Superfilling Facilitates Embedded Lithium Anode for High-Areal-Capacity Solid-State Batteries

Solid-state batteries based on lithium metal anodes are expected to meet safety challenges while maintaining a high energy density. One major challenge lies in the fast interface degradation between the electrolyte and the lithium metal. Herein, we propose a quasi-3D interphase on a garnet solid-state electrolyte (SSE) by introducing lithiophilic nanotrenches. The nanotrenches created by the lithiophilic nanowire array can induce the superfilling of lithium metal into the nanotrenches, resulting in a low interfacial resistance (4 Ω cm²). Moreover, the embedded lithium metal anode optimizes the lithium deposition/stripping behavior not limited at the Li–SSE interface (∼1–10 nm) but extended into the bulk lithium anode (∼10 μm), realizing a high critical current density of 1.8–2.0 mA cm^–2 at room temperature (RT). The embedded lithium metal anode is further applied in Li||LiFePO₄ solid-state batteries, demonstrating a high reversible areal capacity of ∼3.0 mAh cm^–2 at RT.