Essential properties of AlCl4-related graphite intercalation compounds of aluminum-ion-based battery cathodes

TL;DR

This paper investigates the geometric and electronic properties of AlCl4-related graphite intercalation compounds, focusing on stage-1 and stage-2 configurations, to understand their potential as aluminum-ion battery cathodes.

Contribution

It provides detailed simulations and analyses of the structural and electronic features of AlCl4 intercalated graphite, highlighting properties relevant for battery applications.

Findings

Stage-4 and stage-3 compounds are experimentally observed.

Stage-1 and stage-2 compounds are difficult to synthesize due to structural constraints.

Distinct electronic features such as van Hove singularities are identified.

Abstract

Up to now, many guest atoms/molecules/ions have been successfully synthesized into graphite to form the various compounds. For example, alkali-atom graphite intercalation compounds are verified to reveal the stage-n structures, including LiC6n and LiM8n [M=K. Rb and Cs; n=1, 2, 3; 4]. On the other side, AlCl4-ion/molecule ones are examined to show stage-4 and stage-3 cases at room and lower temperatures, respectively. Stage-1 and stage-2 configurations, with the higher intercalant concentrations, are unable to synthesize in experimental laboratories. This might arise from the fact that it is quite difficult to build the periodical arrangements along the longitudinal z and transverse directions simultaneously for the large ions or molecules. Our works are mainly focused on stage-1 and stage-2 systems in terms of geometric and electronic properties. The critical features, being associated with the atom-dominated energy spectra and wave function within the specific energy ranges, the active multi-orbital hybridization in distinct chemical bonds, and atom- & orbital-decomposed van Hove singularities, will be thoroughly clarified by the delicate simulations and analyses.