Variation in structure and Li+-ion migration in argyrodite-type Li6PS5X (X = Cl, Br, I) solid electrolytes
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Date
2012-05-01
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Springer
Abstract
All-solid-state rechargeable lithium-ion batteries (AS-LIBs) are attractive power sources for electrochemical applications due to their potentiality in improving safety and stability over conventional batteries with liquid electrolytes. Finding a solid electrolyte with high ionic conductivity and compatibility with other battery components is a key factor in raising the performance of AS-LIBs. In this work, we prepare argyrodite-type Li(6)PS(5)X (X = Cl, Br, I) using mechanical milling followed by annealing. X-ray diffraction characterization reveals the formation and growth of crystalline Li(6)PS(5)X in all cases. Ionic conductivity of the order of 7 x 10(-4) S cm(-1) in Li(6)PS(5)Cl and Li(6)PS(5)Br renders these phases suitable for AS-LIBs. Joint structure refinements using high-resolution neutron and laboratory X-ray diffraction provide insight into the influence of disorder on the fast ionic conductivity. Besides the disorder in the lithium distribution, it is the disorder in the S(2-)/Cl(-) or S(2-)/Br(-) distribution that we find to promote ion mobility, whereas the large I(-) cannot be exchanged for S(2-) and the resulting more ordered Li(6)PS(5)I exhibits only a moderate conductivity. Li(+) ion migration pathways in the crystalline compounds are modelled using the bond valence approach to interpret the differences between argyrodites containing different halide ions. © 2012, Springer.
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Keywords
Lithium, Lithium ions, Chemical bonds, Valence, Ions, Neutron diffraction
Citation
Rayavarapu, P. R., Sharma, N., Peterson, V. K., & Adams, S. (2012). Variation in structure and Li+-ion migration in argyrodite-type Li6PS5X (X = Cl, Br, I) solid electrolytes. Journal of Solid State Electrochemistry, 16(5), 1807-1813. doi:10.1007/s10008-011-1572-8