A New Class of Lithium Ion Conductors with Tunable Structures and Compositions: Quaternary Diamond-like Thiogermanates
Solid State Ionics
LISICON, Ion conductivity, Thiogermanate, Solid-state electrolyte, Kesterite, Stannite
The new Li2CoGeS4 compound crystallizes in the Pn space group with the wurtz-kesterite structure, according to single crystal X-ray diffraction. The structure of Li2CoGeS4 and the high degree of phase-purity in which it is prepared are supported by high-resolution synchrotron X-ray powder diffraction. Varying the divalent ion in Li2-II-GeS4 materials yields three different structure types, all of which are derived from hexagonal diamond. These structural variations give rise to Li+-encompassing [II–GeS4]2 − nets with different topologies that offer diversity in lithium ion diffusion pathways. In the first systematic study of the lithium ion conductivity in quaternary diamond-like materials, wurtz-kesterite-type Li2CoGeS4 and Li2FeGeS4 (Pn), lithium cobalt(II) silicate-type Li2MnGeS4 (Pna21), and wurtz-stannite-type Li2CdGeS4(Pmn21) are presented as environmentally stable lithium ion conductors. These materials are comprised of cubic diamond-like [CoGeS4]2 − and [FeGeS4]2 −anionic frameworks, ABW-like [MnGeS4]2 −, and square lattice-like [CdGeS4]2 −. As assessed using impedance spectroscopy, Li2FeGeS4 exhibits the most promising Li+ ion conductivity of 1.8(3) × 10− 4 S/cm at 100 °C, while Li2CdGeS4 shows the lowest activation energy for lithium ion conduction, EA = 0.74(2) eV.
Brant, J. A., Devlin, K. P., Bischoff, C., Watson, D., Martin, S. W., Gross, M. D., & Aitken, J. A. (2015). A New Class of Lithium Ion Conductors with Tunable Structures and Compositions: Quaternary Diamond-like Thiogermanates. Solid State Ionics, 278, 268 - 274. https://doi.org/10.1016/j.ssi.2015.05.019. Retrieved from https://nsuworks.nova.edu/cnso_chemphys_facarticles/172