Electric double layer studies of Li electrode-PEO-LiTFSI electrolyte by constant potential simulations.

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• Electrochemical interfaces are critical for advanced battery technologies.
• Understanding the Li metal-polymer electrolyte interface is essential for improving battery performance.

Purpose of the Study:

• To investigate the structure and transport properties of the Li metal-PEO-LiTFSI polymer electrolyte interface.
• To elucidate the role of charge transfer, ion adsorption, and electric potential in interface behavior.

Main Methods:

• Density functional theory (DFT) computations.
• Molecular dynamics (MD) simulations.

Main Results:

• Significant charge transfer occurs between PEO chains and the Li surface.
• Distinct differences exist between negative (polymer/Li+ dominated) and positive (anion dominated) interfaces.
• Li+ ion adsorption on the Li slab is observed at high salt concentrations and potentials.
• Li+ transport kinetics are slow, especially near the negative electrode, and do not correlate with adsorption energy.
• Electric potential has a minor effect on Li+ adsorption.

Conclusions:

• Slow interface kinetics, particularly at the negative electrode, may impede charge transfer and lead to non-uniform Li plating.
• The findings provide insights into the challenges of Li metal anode stability in polymer electrolytes.
• Further research is needed to optimize interface properties for better battery performance.