Significance Rechargeable lithium metal batteries are promising next-generation high-energy-density energy storage systems. However, their applications have been greatly impeded by the instabilities of electrolytes toward both highly reductive lithium metal anode and high-voltage cathodes. Here, we use localized high-concentration electrolytes to investigate the fundamental correlation between the battery performance and the electrolyte solvation chemistry and its profound electrode/electrolyte interphase properties. Experimental and theoretical analyses reveal an intriguing general rule that the strong interactions between the salt and the solvent in the inner solvation sheath within the salt–solvent complexes promote their intermolecular proton/charge-transfer reactions, dictate the properties of the electrode/electrolyte interphases, and then influence the battery performances. These findings can shed light for rational electrolyte design for various battery systems.