In Situ-Constructed Lithiophobic-Lithiophilic Gradient Interlayer Enabling Ultrahigh Critical Current Density for Sulfide-Based Solid-State Lithium Batteries

All-solid-state lithium batteries are expected to achieve high energy density but suffer from the issues of lithium dendrite and anodic interfacial reaction. Herein, a lithiophilic-lithiophobic gradient interlayer of lithium-contained alloy/LiF is in situ constructed on a lithium anode by metal trifluoromethanesulfonate (OTf^-) salt modification. The upper lithiophobic layer is rich in LiF to avoid deposition of lithium on the solid-state electrolyte/lithiophobic layer interface, while the lithiophilic alloy layer induces uniform lithium deposition. In this study, three metals with lithiophilic properties (Ag, In, and Al) were selected to form alloys with lithium. Among them, Ag exhibited notable advantages during the alloying process owing to its unique chemical characteristics and forms Li-Ag alloy with continuously varying compositions to regulate the deposition behavior of lithium. As a result, AgOTf@Li/LPSC/AgOTf@Li symmetric batteries with a gradient interlayer exhibited a high critical current density of 8.0 mA cm^-2. The NCM/LPSC/AgOTf@Li all-solid-state battery can have an areal capacity of 0.345 mA h cm^-2 at a high mass loading of 6.5 mg and a high current density of 1.2 mA cm^-2.