Developing high-performance all-solid-state batteries is contingent on finding solid electrolyte materials with high ionic conductivity and ductility.Here we report new halide-rich solid solution phases in the argyrodite Li 6 PS 5 Cl family, Li 6Àx PS 5Àx Cl 1+x ,a nd combine electrochemical impedance spectroscopy, neutron diffraction, and 7 Li NMR MAS and PFG spectroscopytoshow that increasing the Cl À /S 2À ratio has as ystematic, and remarkable impact on Li-ion diffusivity in the lattice.T he phase at the limit of the solid solution regime, Li 5.5 PS 4.5 Cl 1.5 ,e xhibits ac old-pressed conductivity of 9.4 AE 0.1 mS cm À1 at 298 K( and 12.0 AE 0.2 mS cm À1 on sintering)almost four-fold greater than Li 6 PS 5 Cl under identical processing conditions and comparable to metastable superionic Li 7 P 3 S 11 .W eakened interactions between the mobile Li-ions and surrounding framework anions incurred by substitution of divalent S 2À for monovalent Cl À play amajor role in enhancing Li + -ion diffusivity,a long with increased site disorder and ahigher lithium vacancy population. Figure 5. a) 7 Li MAS NMR for Li 6Àx PS 5Àx Cl 1+x (x = 0, 0.25, 0.375, 0.5) b) correlation of the activation energies from both techniques with the 7 Li isotropic chemical shift and the Haven ratio for all values of x under study.

X-ray and neutron diffraction, Raman spectroscopy, complex impedance spectroscopy and electron microscopy were used to characterize the tetragonal vs. cubic phase stability in superionic conducting garnet-oxide electrolyte.

No abstract

The high-voltage doped spinel oxides LiMn 1.5 Ni 0.5−x M x O 4 (M = Cr, Fe, and Ga; 0 ≤ x ≤ 0.08) synthesized at 900°C have been investigated systematically before and after postannealing at 700°C. Neutron diffraction studies reveal that the cation-ordered domain size tends to increase upon annealing at 700°C. Time-of-flight secondary-ion mass spectroscopy data reveal that the dopant cations M = Cr, Fe, and Ga segregate preferentially to the surface, resulting in a more stable cathode−electrolyte interface and superior cyclability at both room temperature and 55°C with conventional electrolytes. The doping with Cr and Fe stabilizes the structure with a significant disordering of the cations in the 16d sites even after postannealing at 700°C, resulting in high rate capability due to low charge-transfer resistance and polarization loss. In contrast, the Ga-doped and undoped LiMn 1.5 Ni 0.5 O 4 samples experience an increase in cation ordering upon postannealing at 700°C, resulting in degradation in the rate capability due to an increase in the charge-transfer resistance and polarization loss.