First Principles Study of Li-Ion Complex Binding on Lithium Metal Surfaces

Lithium-metal anodes would allow lithium-ion batteries to have higher gravimetric energy densities due to their low mass density and low electrochemical potential. They tend to form dendrites, however, which can lead to safety issues which limit their use in batteries. Dendrites form on lithium metal batteries as a consequence of SEI formation, necessitating further optimization of the electrolytic inputs. Prior work [1] developed an accurate machine-learned force field that provides ab initio quality insights into the molecular complexation of Li ions in ethylene carbonate solution. Using first principles density functional theory calculations, we study the interaction of solvated lithium ion complexes taken from molecular dynamics with our machine-learned force field with lithium metal surfaces. We assess the performance of different exchange-correlation functionals in calculating binding energetics of the solvated lithium ions, and show how different solvation environments modify the binding sites and energetics of lithium ions on lithium surfaces. We study charge transfer in these different binding modes, and assess how different complexes contribute to the early stages of SEI formation.

[1] J. Phys. Chem. B 2022, 126, 33, 6271–6280