Silver‐Decorated Graphene Mediates “Lithiene” Structured Interlayers for Ultrafast Lithium Transport in Solid‐State Batteries

Abstract

ABSTRACT Solid‐state lithium metal batteries (SSLMBs) employing garnet‐type Li 6.5 La 3 Zr 1.5 Ta 0.5 O 12 (LLZTO) electrolytes offer a pathway to high energy density but are plagued by interfacial impedance and catastrophic dendrite propagation. Current interfacial engineering strategies often fail to fundamentally alter the thermodynamic tendency of lithium to grow in uncontrolled three‐dimensional (3D) dendritic morphologies, severely limiting critical current densities. Here, a mechanism‐driven design of a “lithiene” structured interlayer enabled by chemically bonded Ag nanoparticles anchored on vertically aligned reduced graphene oxide (rGO) nanosheets is reported. This architecture fundamentally reconfigures lithium deposition dynamics: the lithiophilic Ag sites lower the nucleation energy barrier via Li–Ag alloying, while the conductive rGO framework acts as a two‐dimensional (2D) template that kinetically confines lithium growth within its lamellar interspaces. In situ field‐emission scanning electron microscopy, in situ x‐ray photoelectron spectroscopy, and—implemented for the first time in battery research—in situ energy‐tunable hard x‐ray photoelectron spectroscopy (HAXPES) reveal a sequential deposition mechanism. Epitaxial Li–Ag alloying followed by Li intercalation and subsequent planar growth along the rGO basal planes is observed, effectively transforming bulk lithium into a 2D “lithiene‐like” morphology. Consequently, the modified SSLMBs achieve unprecedented rate capabilities of 4 C (3.0 mA cm −2 ) at 25°C and 7 C (4.7 mA cm −2 ) at 60°C, alongside 97% capacity retention over 440 cycles. These findings provide a physical chemistry framework for manipulating the dimensionality of lithium crystallization, offering a scalable route to dendrite‐free, high‐rate solid‐state batteries.