Nature Sustainability, Published online: 26 June 2026; doi:10.1038/s41893-026-01866-z Interfacial electrochemical reaction kinetics are crucial to fast charging and low-temperature operation of batteries. We now reveal that solvent exchange dynamics of solvated ions are intrinsically coupled with their interfacial electrochemical reaction kinetics. An electrolyte designed using this insight enables fast charging and low-temperature operation in lithium-ion batteries.