Efficient simulations of mobility matrices for electrolytes by applying forces.

Area of Science:

• Computational materials science
• Electrochemistry
• Physical chemistry

Background:

• Ion drift velocities are essential for battery electrolyte performance.
• Predicting species mobilities in atomistic simulations is a significant challenge.
• Two common organic liquid electrolytes studied are LiPF6 in dimethyl carbonate (DMC) and a DMC/ethylene carbonate (EC) mixture.

Purpose of the Study:

• To compare the computational efficiency and statistical accuracy of two methods for measuring ion mobilities in battery electrolytes.
• To investigate the influence of system size and simulation time on the statistical errors of each method.
• To determine the preferred method for practical application in atomistic simulations.

Main Methods:

• Investigated LiPF6 in DMC and a DMC/EC mixture using atomistic simulations.
• Measured ion mobilities by observing center of mass diffusion (no applied forces).
• Measured ion mobilities by observing species drift under external electric fields.

Main Results:

• The drift method exhibited significantly smaller variance in repeated measurements compared to the diffusion method.
• Statistical errors were found to scale differently with system size and simulation time for the two methods.
• The drift method demonstrated superior computational efficiency for mobility measurements.

Conclusions:

• The drift method is statistically more robust and computationally efficient for measuring ion mobilities in battery electrolytes.
• The drift method should be preferred over the diffusion method for practical atomistic simulations.
• Accurate prediction of species mobilities is critical for advancing battery electrolyte design and performance.