Elsevier

Solid State Sciences

Volume 55, May 2016, Pages 83-87
Solid State Sciences

LiCuS, an intermediate phase in the electrochemical conversion reaction of CuS with Li: A potential environment-friendly battery and solar cell material

https://doi.org/10.1016/j.solidstatesciences.2016.02.010Get rights and content
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Highlights

  • Li1.1Cu0.9S forms as an intermediate phase in the reaction of CuS with Li.

  • The compound crystallize in the Na3AgO2 structure type, which is related to Li2S.

  • The metal atoms are tetrahedrally or linearly coordinated by sulphur atoms.

  • Li1.1Cu0.9S is yellow in powder form and a direct bandgap semiconductor.

Abstract

The crystal structure of a ternary sulfide with the approximate composition LiCuS, which is a promising candidate for environment-friendly battery and solar cell materials is reported. The crystal structure was solved by a combination of neutron and X-ray powder diffraction data, and 7Li solid-state NMR analysis. A yellow powder, Li1.1Cu0.9S, was obtained by the reaction of CuS with a slight excess of Li metal. The compound crystallizes in the Na3AgO2 structure type in the space group Ibam. An idealized crystal structure of Li1.1Cu0.9S can be derived from the cubic Li2S structure by moving a part of the Li along the c axis so that these Li atoms become linearly coordinated by S. All the metal sites are occupied by randomly mixed Li and Cu atoms; however, there is a strong preference for linear coordination by Cu. The density functional theory calculations show that Li1.1Cu0.9S is a direct band-gap semiconductor with an energy gap of 1.95 eV in agreement with experimental data.

Keywords

Li-ion batteries
Crystal structure
DFT calculations
Optoelectronics
New materials
NMR

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