Causal Relationship between Potential Shift and Molecular Structure in Concentrated Electrolytes.

Area of Science:

• Electrochemistry
• Materials Science
• Computational Chemistry

Background:

• Concentrated electrolytes are vital for high-energy-density lithium-metal batteries.
• Understanding potential shifts is crucial for battery stability and performance.
• Previous work highlighted Li+-anion interactions but lacked causal insight.

Purpose of the Study:

• To investigate the causal relationships governing potential shifts in concentrated electrolytes.
• To apply causal discovery methods to electrochemical systems.
• To identify key descriptors influencing electrode potential.

Main Methods:

• Utilized Linear Non-Gaussian Acyclic Model (LiNGAM) for causal discovery.
• Analyzed 75 electrolyte solutions with LiFSI salt and various solvents.
• Employed molecular dynamics simulations to derive 132 descriptors (molecular and intermolecular).
• Used a genetic algorithm for descriptor dimensionality reduction.

Main Results:

• Li+-anion spatial distribution descriptors, particularly long-range NDF, showed a direct causal effect on potential.
• Intrinsic molecular properties did not exhibit causal relationships with potential shifts.
• Findings support theoretical frameworks emphasizing liquid-phase Madelung interactions.

Conclusions:

• Causal discovery effectively identifies fundamental physical mechanisms in electrochemistry.
• Electrolyte potential shifts are primarily governed by Li+-anion spatial arrangements.
• This research advances the design principles for advanced lithium-metal batteries.