Disappearance of Electro-Freezing in Salt Solutions Beyond a Critical Ion Concentration: Salt-Type Independence

Static electric fields have been widely proposed to control freezing temperatures, but previous studies have been focused on pure water, leaving the underlying mechanisms incompletely understood. Here, we systematically investigate electrofreezing in salt solutions across varying concentrations and ion types. Our experiments demonstrate that above a critical ionic concentration, the field's nucleation-promoting effect is significantly weakened or even eliminated. Molecular dynamics simulations reveal that strongly hydrated ions disrupt local electric fields, interfering with water molecule alignment induced by the external field and preventing the formation of ordered interfacial structures necessary for ice nucleation. At high concentrations, a salt-enriched interfacial layer further suppresses ice crystal growth, ultimately nullifying the electrofreezing effect. These findings provide new insights into ice nucleation mechanisms under complex ionic conditions, with important implications for applications requiring precise control over freezing in saline environments.