Ultralow 0.076% Silver Doping: An Efficient Strategy for Suppressing Lithium Penetration in Sulfide Solid Electrolytes

Using an artificial interfacial layer containing silver to modify the interface between the solid electrolyte and the lithium anode is an effective approach to mitigate the issue of lithium dendrite growth in solid electrolytes. This strategy has opened up an important technical pathway for the development of next-generation all-solid-state lithium metal batteries (ASSLMBs) with both high energy density and high safety. However, in conventional strategies employing silver-containing interfacial layers, a high silver loading is required, which increases cost and hinders large-scale commercialization. In this work, we report an ultralow dose of Ag (0.076 wt %) doped into 73Li2S-27P2S5 (Ag-LPS), which promotes the in situ formation of a dynamically stable mixed conducting interphase (MCI) layer at the interface. This trace doping strategy significantly enhances the CCD to exceeding 7.4 mA cm–2. Symmetric Li|Ag-LPS|Li cells achieve stable cycling for over 300 h at 0.5 mA cm–2. Moreover, full cells configured as Li4Ti5O12|Li5.5PS4.5Cl1.5|Ag-LPS|Li exhibit excellent cycling stability, retaining 93% of their initial capacity after 80 cycles at 1C. This work provides a practical and cost-effective strategy for in situ creation of a stable MCI layer via trace Ag doping, effectively suppressing lithium dendrite growth and advancing the development of high-performance ASSLMBs.