In Situ Formed Shields Enabling LiCO-Free Solid Electrolytes: A New Route to Uncover the Intrinsic Lithiophilicity of Garnet Electrolytes for Dendrite-Free Li-Metal Batteries.

Introduction of inorganic solid electrolytes is believed to be an ultimate strategy to dismiss dendritic Li in high-energy Li-metal batteries (LMBs), and garnet-type LiLaZrO (LLZO) electrolytes are impressive candidates. However, the current density for stable Li plating/stripping in LLZO is still quite limited. Here, we create in situ formed Li-deficient shields by the high-temperature calcination at 900 °C. By this novel process, the formation of LiCO on LLZO is restrained, and then we successfully obtain LiCO-free LLZO after removing the Li-deficient compounds. Without any surface modification, LiCO-free LLZO shows an intrinsic "lithiophilicity" characteristic. The contact angles of metallic Li on LLZO garnets are assessed by the first-principle calculation to confirm the lithiophilicity characteristic of LLZO electrolytes. The wetting of metallic Li on the LiCO-free LLZO surface leads to a continuous and tight Li/LLZO interface, resulting in an ultralow interfacial resistance of 49 Ω cm and a homogeneous current distribution in the charge/discharge processes of LMBs. Consequently, the current density for the stable Li plating/stripping in LLZO increases to 900 μA cm at 60 °C, one of the highest current density for LMBs based on garnet-type LLZO electrolytes. Our findings not only offer insight into the lithiophilicity characteristics of LLZO electrolytes to suppress dendritic Li at high current densities but also expand the avenue toward high-performance, safe, and long-life energy-storage systems.