Thermodynamic and Mechanical Stability of Crystalline Phases of Li 2 S 2

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Department of Physics


In lithium-sulfur (Li-S) battery, Li 2 S 2 is one of the key intermediate products which may exist as an insoluble solid in a battery system. In this article, the low-energy crystalline phases of Li 2 S 2 are investigated using density functional theory coupled with the Van Der Waals correction terms. The calculated results find that the tetragonal, triclinic, and hexagonal phases of Li 2 S 2 phases are thermodynamically stable with the preference for the hexagonal phase to be the ground state. The low-energy Li 2 S 2 phases also exhibit highly anisotropic elastic properties which can be attributed to the unique S-S bond orientations in their lattices. We believe that the elastic modulus in Li-S solids can be properly tuned if the S-S bonds orientation and distribution can be controlled during the synthesis process, which may be helpful for the development of functionalized cathode in the Li-S battery.

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© 2019 American Chemical Society. Publisher’s version of record: https://doi.org/10.1021/acs.jpcc.8b11290

Publication Title

Journal of Physical Chemistry C