Comprehending the progressive structure of molten salt by deep potential molecular dynamics for high temperature heat storage

Abstract

Investigating the microscopic structure of molten salt holds extensive theoretical and practical significance for understanding their thermal properties and designing the novel functional materials. Here, we address the deep potential function of molten salt by the Deep Potential GENerator (DP-GEN) enhanced sampling method, and interpret the structure evolution of molten salt. Na + typically forms tetrahedral and hexagonal structures with surrounding anions, while K + commonly forms tetrahedral, hexagonal, and octahedral structures with surrounding anions. When Na + is positioned at the body center, it forms an octahedral structure with surrounding anions. When K + is located at the vertex or body center, it forms an octahedral structure with surrounding anions, and the octahedral structure centered on K + can further form a decahedral structure with another anion. High temperatures can cause unstable high-coordination structures to distort until they disintegrate. These microscopic insights might reshape the fundamental understanding on thermal properties of matter and open up a general opportunity to design of thermal energy storage material.