Density Functional Theory screening of gas-treatment strategies for stabilization of high energy-density lithium metal anodes

TL;DR

This study uses density functional theory to investigate how different molecular gases interact with lithium metal surfaces, aiming to develop non-electrolyte passivation methods to stabilize high energy-density lithium anodes.

Contribution

The paper provides a detailed computational analysis of gas decomposition on lithium surfaces, identifying SO2 as a promising candidate for insulating passivation layers.

Findings

SO2 creates effective insulating passivation layers on lithium surfaces.

Gas exposure induces surface reconstructions and alters work functions.

Nitrogen causes minimal elastic changes compared to other gases.

Abstract

To explore the potential of molecular gas treatment of freshly cut lithium foils in non-electrolyte based passivation of high energy-density Li anodes, density functional theory (DFT) has been used to study the decomposition of molecular gases on metallic lithium surfaces. By combining DFT geometry optimization and Molecular Dynamics, the effects of atmospheric (N2, O2, CO2) and hazardous (F2, SO2) gas decomposition on Li(bcc) (100), (110), and (111) surfaces on relative surface energies, work functions, and emerging electronic and elastic properties are investigated. The simulations suggest that exposure to different molecular gases can be used to induce and control reconstructions of the metal Li surface and substantial changes (up to over 1 eV) in the work function of the passivated system. Contrary to the other considered gases, which form metallic adlayers, SO2 treatment emerges as the most effective in creating an insulating passivation layer for dosages <= 1 mono-layer. The substantial Li->adsorbate charge transfer and adlayer relaxation produce marked elastic stiffening of the interface, with the smallest change shown by nitrogen-treated adlayers.