Refined method for predicting electrochemical windows of ionic liquids and experimental validation studies

Area of Science:

• Computational Chemistry
• Materials Science
• Electrochemistry

Background:

• Accurate prediction of electrochemical windows (ECWs) for ionic liquids is crucial for their application in electrochemical devices.
• Experimental determination of ECWs is sensitive to setup and conditions, making direct comparisons challenging.
• Existing simulation methods often lack the accuracy or efficiency needed for reliable ECW prediction.

Purpose of the Study:

• To develop and validate a novel computational approach for calculating the ECWs of ionic liquids.
• To provide a method for consistent and quantitative comparison of ECWs across different ionic liquids.
• To improve the efficiency and accuracy of predicting ionic liquid performance in electrochemical applications.

Main Methods:

• A hybrid approach combining classical molecular dynamics (MD) for liquid phase sampling with ab initio MD (AIMD) for accurate electronic structure calculations.
• Density functional theory (DFT) was used to calculate the energy difference between the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) from stable configurations.
• Snapshots from classical MD trajectories were relaxed using AIMD and quenched to local energy minima to ensure accurate HOMO/LUMO calculations.

Main Results:

• The developed method accurately predicts the experimental trends of ECWs for a series of ionic liquids.
• Quantitative agreement between predicted and experimentally measured ECW values was achieved.
• The method demonstrates high efficiency in comparing ECWs of ionic liquids under consistent conditions.

Conclusions:

• The combined classical MD and AIMD method offers an efficient and accurate approach for calculating ionic liquid ECWs.
• This computational tool facilitates reliable comparison of ionic liquids, overcoming experimental variability.
• The findings pave the way for accelerated discovery and optimization of ionic liquids for electrochemical technologies.