Localized Medium Concentration Electrolyte with Fast Kinetics for Lithium Metal Batteries

Localized high‐concentration electrolyte is widely acknowledged as a cutting‐edge electrolyte for the lithium metal anode. However, the high fluorine content, either from high‐concentration salts or from highly fluorinated diluents, results in significantly higher production costs and an increased environmental burden. Here, we have developed a novel electrolyte termed "Localized Medium‐Concentration Electrolyte" (LMCE) to effectively address these issues. This LMCE is designed and produced by diluting a medium concentration (0.5 M – 1.5 M) electrolyte which is incompatible with lithium metal anode before diluting. It has ultralow concentration (0.1 M) and demonstrates remarkable compatibility with lithium metal anode. Surprisingly, our LMCE, despite having an ultralow concentration (0.1 M), exhibits excellent kinetics in Li/Cu, Li/Li, LiFePO4/Li, and NCM811/Li batteries. Additionally, LMCE effectively inhibits the corrosion of the Al current collector caused by LiTFSI salt under high voltage (> 4 V) conditions. This groundbreaking LMCE design transforms the seemingly "incompatible" into the "compatible", opening up new avenues for exploring various electrolyte formulations, including all liquid electrolyte‐based batteries.