Synergistic bulk and interfacial engineering of Li2OHBr antiperovskite electrolyte for stable solid-state lithium-metal batteries

Lithium-rich antiperovskite (LiRAP) solid electrolytes, exemplified by Li 2 OHBr, have emerged as promising candidates for all-solid-state lithium-metal batteries owing to their high lithium content, low activation energy, and scalable processability. However, their practical implementation is hindered by practical ionic conductivity and pronounced interfacial instability against lithium metal, which together induce nonuniform Li + flux, localized current accumulation, and accelerated lithium dendrite formation. Herein, we report a synergistic bulk–interface engineering strategy to fundamentally stabilize the Li 2 OHBr/lithium metal interface. Fluorine doping is introduced to modulate the bulk Li 2 OHBr framework, enhancing Li + transport and homogenizing ionic flux, while a graphite interlayer is employed to construct an adaptive and ion-favorable interfacial environment. Experimental results demonstrate that graphite reacts with lithium metal to form a lithium-containing transitional phase that facilitates efficient interfacial Li + transport. DFT calculations further reveal that Li + migrates rapidly along the graphite surface with an energy barrier substantially lower than its adsorption energy, enabling fast interfacial redistribution and preventing Li + accumulation. Benefiting from the coupled enhancement of bulk ion transport and dynamic interfacial regulation, lithium-metal symmetric cells achieve stable cycling for over 900 h. This work provides insights into adaptive interfacial design and establishes a strategy for advancing LiRAP-based all-solid-state lithium-metal batteries.