High Lithium Ionic Mobility in Mo6S8 Chevrel Phase Cathodes

Rechargeable magnesium batteries have been recognized as an alternative solution to lithium ion batteries because of their advantages of excellent safety and cost [1]. Chevrel phase compounds, M_xMo₆S₈(M = metal), are promising cathode materials in Mg batteries, because they display exceptionally fast cation transport for multi-valent ions compared to any other host materials.  However, depending upon the composition and synthesized temperature of the Chevrel phase, the kinetics of Mg diffusion is highly affected at both room temperature and elevated temperature.

In addition, there are many on-going efforts to discover improved electrolytes for Mg batteries.  It has been recently demonstrated that using an electrolyte with a concentrated lithium salt could benetit the thermodynamic and kinetic in a lithium-sulfur cell [2].  Here, we report the experimental and computational calculation results to explain unusually high ionic mobility of lithium in Mo₆S₈ chevrel phase cathode materials.  When a concentrated lithium salt of 0.5M LiCl is added to the conventional APC electrolytes, almost full theoretical capacity can be achieved at room temperature in Mo₆S₈ Chevrel phase cathode materials at very high C-rates up to 20, 30C.

 

References

[1] D. Aurbach, Z. Lu, A. Schechter, Y. Gofer, H. Gizbar, R. Turgeman, Y. Cohen, M. Moshkovich, and E. Levi, Nature, 407, 724 (2000).

[2] E. S. Shin, K. Kim, S. H. Oh, W. I. Cho, Chem. Comm., 49, 2004 (2013).