Liquid Structure with Nano-Heterogeneity Promotes Cationic Transport in Concentrated Electrolytes

Area of Science:

• Electrochemistry
• Materials Science
• Physical Chemistry

Background:

• Aqueous electrolytes are crucial for battery technologies.
• High salt concentrations typically lead to increased viscosity and hindered ion transport.

Purpose of the Study:

• To investigate ion solvation and transport in superconcentrated aqueous electrolytes.
• To understand the structural origins of enhanced ion mobility.

Main Methods:

• Molecular dynamics simulations
• Small-angle neutron scattering
• Spectroscopic techniques

Main Results:

• Disproportionation of cation solvation at high salt concentrations (10-21 mol/kg).
• Formation of nano-heterogeneous domains (1-2 nm scale).
• Emergence of a 3D percolating lithium-water network facilitating fast cation transport.
• High lithium-transference number (0.73) observed.

Conclusions:

• Nano-heterogeneity decouples cations from anions, enabling efficient transport.
• Superconcentrated electrolytes offer a promising pathway for high-rate battery applications.
• Understanding these mechanisms guides the design of advanced electrolyte systems.