Scientific Achievement

Van der Waals-augmented density functional theory (vdW-DF), quasi-particle methods (G₀W₀), and continuum solvation techniques were used to predict several structural, thermodynamic, spectroscopic, electronic, and surface characteristics of solid-phase redox end-members in Li-S batteries.

Significance and Impact

• The stability of lithium persulfide, Li₂S₂, a compound whose presence may limit the capacity of Li-S batteries, was assessed by comparing the energies of hypothetical A₂B₂ crystal structures.
• In all cases Li₂S₂ is predicted to be unstable with respect to a two-phase mixture of Li₂S and α-S, suggesting that Li₂S₂ is a metastable phase.

Research Details

The stable surfaces and equilibrium crystallite shapes of Li₂S and α-S were predicted in the presence of a continuum solvation field intended to mimic the effect of a dimethoxyethane (DME)-based electrolyte.

 

Work performed at the University of Michigan (JCESR partner) by H. Park, H. S. Koh and D. J Siegel. J. Phys. Chem. C., 2015, 119, 4675-4683.

DOI: 10.1021/jp513023v

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