Fluid Structure of Molten LiCl-Li Solutions

Area of Science:

• Materials Science
• Electrochemistry
• Physical Chemistry

Background:

• Molten LiCl-Li mixtures are vital for electrolytic reduction of metal oxides.
• Their high-temperature properties are studied, but Li dissolution remains unclear due to reactivity.
• Previous research lacked definitive proof of Li dissolution's physical nature.

Purpose of the Study:

• To investigate the structural evolution of molten LiCl-Li during in situ electrochemical Li introduction.
• To elucidate the physical nature of lithium dissolution in molten lithium chloride.
• To model the structure of Li nanoclusters formed in the melt.

Main Methods:

• In situ synchrotron X-ray scattering (WAXS and SAXS) to probe structural changes.
• Electrochemical introduction of metallic lithium into molten LiCl.
• Ab initio molecular dynamics (AIMD) simulations for structural modeling.

Main Results:

• Time-resolved X-ray scattering revealed transient chloride ion (Cl-) cages.
• These cages surrounded low-density voids with a periodicity of approximately 8.3 Å.
• Evidence suggests the formation of metastable lithium (Li) nanoclusters, predominantly Li8.

Conclusions:

• The study provides in situ structural evidence for Li nanocluster formation in molten LiCl.
• AIMD simulations support the X-ray diffraction findings, identifying Li8 as the dominant cluster size.
• This research clarifies the physical nature of Li dissolution in LiCl-Li melts.