Structure–transport correlations in Na11Sn2SbSe12 and its sulfide solid solutions
Erika P. Ramos,
Abdeljalil Assoud,
Laidong Zhou,
Abhinandan Shyamsunder,
Daniel Rettenwander,
Linda F. Nazar
Affiliations
Erika P. Ramos
Department of Chemistry and the Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Ave. W, Waterloo, Ontario N2L 3G1, Canada
Abdeljalil Assoud
Department of Chemistry and the Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Ave. W, Waterloo, Ontario N2L 3G1, Canada
Laidong Zhou
Department of Chemistry and the Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Ave. W, Waterloo, Ontario N2L 3G1, Canada
Abhinandan Shyamsunder
Department of Chemistry and the Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Ave. W, Waterloo, Ontario N2L 3G1, Canada
Daniel Rettenwander
Institute for Chemistry and Technology of Materials, Graz University of Technology (NAWI Graz), Stremayrgasse 9, 8010 Graz, Austria
Linda F. Nazar
Department of Chemistry and the Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Ave. W, Waterloo, Ontario N2L 3G1, Canada
We report a new ion conductor—Na11Sn2SbSe12—as a possible candidate for a solid catholyte in composite cathodes for all-solid state Na-batteries, which exhibits a room temperature ionic conductivity of 0.15 ± 0.03 mS cm−1 and an activation energy of 0.39 ± 0.02 eV. The sulfide solid solutions of Na11Sn2SbSe12, namely, Na11Sn2SbS12−xSex (x = 1 and 6), were also investigated through a combination of Rietveld refinement against powder x-ray diffraction data and electrochemical impedance spectroscopy to reveal the complex structure–property relationships governing ion transport in this class of materials. Meanwhile, broadening of the Na-ion diffusion pathways in Na11Sn2SbSe12 is expected to facilitate Na-ion transport compared to the sulfide-rich member of the solid solution, the opposite holds: increasing the Se fraction in Na11Sn2SbS12−xSex leads to a little change in the activation energy but a reduction in the ionic conductivity. We ascribe this to the lowering of the prefactor, σ0, in the Arrhenius relationship with increasing lattice “softening” as a function of higher Se content.
