Creating a Chevrel Hybrid Mo6S_8-ySe_y to Improve the Performance of Beyond Li-Ion Batteries

Attempting to solve the energy crisis, we consider the use of beyond Li-ion batteries. We are especially interested in the use of Ca and Al metals, due to their abundance within Earth’s crust. Ca and Al are more cost-effective, and environmentally friendly than Li. Additionally, the increased valency increases the energy density. We consider the Chevrel phase (CP), Mo₆X₈ where X= S, Se, Te, as a cathode for Ca-ion batteries. The CP cathode has widely been studied as a cathode for multivalent ion batteries. Several studies have shown that changing the chalcogen X, impacts the potential and diffusion kinetics. Literature shows that the S-rich CP yields a high voltage, with sluggish ion mobility; compared to the Se-rich CP which exhibits a lower voltage and improved ion mobility. We evaluate several S/Se chalcogen concentrations, testing 256 unique configurations, to tune both the potential and diffusion kinetics. Density functional theory is used to investigate the electronic properties, stability, diffusion kinetics, and voltage properties of CaMo6S_8-ySe_y, where y = 0-8. We implement the SCAN functional, a meta-GGA for an improved level of theory.