Determining the degree and the spatial extent of structural order in liquids is a grand challenge. Here, we are able to resolve the structural order in a model organic electrolyte of 1 M lithium hexafluorophosphate (LiPF 6 ) dissolved in 1:1 (v/v) ethylene carbonate:diethylcarbonate by developing an integrated method of liquid-phase transmission electron microscopy (TEM), cryo-TEM operated at −30°C, four-dimensional scanning TEM, and data analysis based on deep learning. This study reveals the presence of short-range order (SRO) in the high–salt concentration domains of the liquid electrolyte from liquid phase separation at the low temperature. Molecular dynamics simulations suggest the SRO originates from the Li + -(PF 6 − ) n ( n  > 2) local structural order induced by high LiPF 6 salt concentration.

The macroscopic behavior of matter is determined by the microscopic arrangement of atoms, but this arrangement is often difficult or impossible to observe experimentally. Instead, researchers use simulation techniques like molecular dynamics to probe the microscopic structure and dynamics of everything from proteins to battery electrolytes. SolvationAnalysis extracts solvation information from completed molecular dynamics simulations, letting researchers access key solvation structure statistics with minimal effort and accelerating scientific research.