Essential electronic properties on stage-1 Li/Li+-graphite-intercalation compounds for different concentrations

TL;DR

This study uses first-principles DFT calculations to analyze the electronic properties of stage-1 Li and Li+ graphite intercalation compounds at various concentrations, revealing differences in electronic behavior and interlayer interactions.

Contribution

It provides detailed insights into the geometric, electronic, and charge distribution properties of Li and Li+ GICs across different concentrations, highlighting the nature of their interlayer interactions.

Findings

Li-GICs exhibit metallic behavior with a Fermi energy shift.

Li+-GICs behave as semimetals similar to graphite.

Weak van der Waals interactions are present between graphite layers.

Abstract

We use first-principles calculation within the density functional theory (DFT) to explore the electronic properties on stage-1 Li- and Li+-graphite-intercalation compounds (GIC) for different concentrations, LiCx/Li+Cx with x= 6,12,18,24,32 and 36. The essential properties, e.g. geometric structures, band structures and spatial charge distributions are determined by the hybridization of orbitals, the main focus of our works. The band structures/density of states/spatial charge distribution display that the Li-GIC possesses blue shift of fermi energy and just like metals, but the Li+-GIC still preserves as original graphite or so-call semimetal possessing the same densities of free electrons and holes. According to these properties, we find that there exists weak but significant van der Waals interactions between interlayer of graphite, and 2s-2pz hybridization between Li and C. There scarcely exists strong interactions between Li+-C. The dominant interaction between the Li and C is 2s-2pz orbital-orbital couple; the orbital-orbital couple is not significant in Li+ and C case but the dipole-diploe couple.