Systematic Investigation into Mg2+/Li+ Dual-Cation Transport in Chevrel Phases Using Computational and Experimental Approaches

Abstract

Computational and experimental investigations into the Li+, Mg2+, and Mg2+/Li+ dual-cation transport properties within the Chevrel phase Mo6S8 have been performed. Five representative paths were selected for 3D diffusion, and their corresponding energy barriers were determined. Based on density functional theory calculation results, we reveal,phenomena of the cation trapping, sluggishness of Mg2+ ion transport, and synchronized movement of inserted cations induced by repulsive interactions. The computational results were further validated by cyclic voltammetry carried out at ambient to high temperatures, from which apparent diffusion constants and activation energies for each case were determined. We found broad agreement between the theoretical and experimental results and suggest an optimum scenario for charge-discharge processes within the dual-cation hybrid system.