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A comprehensive research coupling experiment and computation has been performed to understand the phase transition of Na 3 SbS 4 and to synthesize cubic Na 3 SbS 4 ( c -Na 3 SbS 4 ), a high temperature phase of Na 3 SbS 4 that is difficult to be preserved when cooled down to ambient temperature. The formation of c -Na 3 SbS 4 is verified by Rietveld refinement, nuclear magnetic resonance spectroscopy as well as electrochemical impedance spectroscopy. Unlike tetragonal Na 3 SbS 4 ( t -Na 3 SbS 4 ) appearing phase transition at high temperature, c -Na 3 SbS 4 is stable not just at room temperature but also sustaining thermal cycling up to at least 200 °C. Both experiment and theoretical calculation reveal that the ionic conductivity of c -Na 3 SbS 4 is higher than that of t -Na 3 SbS 4 , though the values are in the same order of magnitude. Both structures allow fast ion transport. All-solid-state cells with c -Na 3 SbS 4 solid electrolyte demonstrate superior Coulombic efficiency, high specific capacity, and relatively good cycling stability. Na 3 SbS 4 solid electrolyte is promising for all-solid-state sodium-ion batteries. [ABSTRACT FROM AUTHOR]

Abstract Sulfide solid electrolytes possess high ionic conductivity and moderate dendrite suppression capability, but rather poor compatibility against oxide cathodes and metallic Li. Here, we report O-doped Li 6 PS 5 Br as solid electrolyte synthesized by a facile solid-state sintering. Different from other O-incorporated sulfides, the O atoms in Li 6 PS 5- x O x Br prefer to substitute the S atoms at free S2− sites rather than those at the PS 4 tetrahedra. Remarkably, without deteriorating the ionic conductivity, this inorganic solid electrolyte with O doping exhibits comprehensively enhanced properties including excellent dendrite suppression capability, superior electrochemical and chemical stability against Li metal as well as high voltage oxide cathodes, and good air stability. Li(Ni 0.8 Co 0.1 Mn 0.1)O 2 and LiCoO 2 -based all-solid-state batteries with Li 6 PS 4.7 O 0.3 Br electrolyte deliver high specific capacity, superior rate capability, and outstanding cycling stability accompanied with low interfacial resistivity. This type of inorganic solid electrolytes is promising for all-solid-state batteries with high energy density. Graphical abstract Image 1 Highlights • O-doped Li 6 PS 5 Br argyrodite is synthesized. • O atoms prefer to occupy the free S2− sites rather than the PS 4 tetrahedra. • Li dendrite is intensively suppressed with O incorporation. • The stability against Li and high voltage cathodes are significantly improved. • NCM-811 and LiCoO 2 cells with Li 6 PS 4.7 O 0.3 Br achieve superior performance. [ABSTRACT FROM AUTHOR]