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Li4OBr2, an n = 1 member of the inverse Ruddlesden–Popper (iRP) phase Li3n+1OnBrn+1, was prepared for the first time by high-pressure (HP) synthesis. The changes in the stability and the ionic cond...

Li9.54Si1.74P1.44S11.7Cl0.3 (LSiPSCl), which exhibits a Li10GeP2S12 (LGPS)-type structure, presents the highest reported Li-ion conductivity for solid electrolytes, but the formation of a secondary...

Single crystals of the lithium-ion conductor Li10GeP2S12 have been successfully grown by the self-flux method and are studied by means of X-ray diffraction and impedance spectroscopy. The weak anis...

Crystal structures of Li10GeP2S12 (LGPS)-type Li10+δ[SnySi1–y]1+δP2−δS12 (Li4–x[SnySi1–y]1–xPxS4) solid electrolytes were analyzed by Rietveld refinement using neutron diffraction data. Maximum ent...

Solid solutions of Sn–Si derivatives with an LGPS (Li10GeP2S12)-type structure are synthesized by a solid-state reaction in the Li3PS4–Li4SnS4–Li4SiS4 quasi-ternary system. The monophasic region of the LGPS-type structure deviates from the tie line between Li10SiP2S12 and Li10SnP2S12, and the composition of the solid solution is determined to be −0.1 ≤ δ ≤ 0.5 and 0 ≤ y ≤ 1.0 in Li10+δ[SnySi1–y]1+δP2−δS12 (0.50 ≤ x ≤ 0.7 and 0 ≤ y ≤ 1.0 in Li4–x[SnySi1–y]1–xPxS4). The solid solution is formed by a double substitution that changes the Sn/Si ratio and the M4+ (Sn4+ and Si4+)/P5+ ratio, which adjusts the sizes of the lithium conduction tunnels and the lithium concentration, and contributes to the optimal conductivity value. The highest ionic conductivity value of 1.1 × 10–2 S cm–1 is achieved for the composition of Li10.35[Sn0.27Si1.08]P1.65S12 (Li3.45[Sn0.09Si0.36]P0.55S4) at 298 K, which is close to the value for the original LGPS compound (1.2 × 10–2 S cm–1). The Ge-free solid electrolyte could be suitabl...

Hydrated materials contain crystal water within their crystal frameworks and can exhibit extraordinary properties as a result. However, a detailed understanding of the mechanism involved in the hydration process is largely lacking, because the overall synthesis process is very difficult to monitor. Here, we elucidate how the insertion of crystal water mediates an anomalous spinel-to-Birnessite phase transition during electrochemical cycling in aqueous media. We find that, at the initial stage of the phase transition, crystal water is inserted into the interlayer space between MnO6 layers in the form of a hydronium ion (H3O+). The H3O+ insertion is chemically driven in the reverse (reducing) direction to the applied anodic (oxidizing) electric field, stabilizing the structure and recovering the charge balance following the deinsertion of Mn2+. A comparative investigation using various electrolyte solutions revealed that the H3O+ insertion competes with the insertion of other ionic charge carriers (Li+, Na+...

Surface and bulk structural changes in LiNi0.8Co0.2O2 were observed during electrochemical reactions using synchrotron X-ray scattering and a restricted reaction plane of two-dimensional (2D) epitaxial-film electrodes. The bulk structural changes confirmed lithium diffusion through the (110) surface, which is perpendicular to the 2D edges of the layered structure. No (de)intercalation reaction was observed through the (003) surface in the voltage range of 3.0−5.0 V. However, intercalation proceeded below 3.0 V, which indicates unusual three-dimensional lithium diffusion in the 2D structure in the overlithiated state. Structural changes at the electrode surface were different from those in the bulk. Contact with the liquid electrolyte caused an abrupt deformation of the surface crystal lattice, followed by restructuring upon applying a cell voltage. These slow reconstruction processes were dependent on the crystal lattice orientations. The reaction mechanism of the intercalation electrodes for lithium batt...

A series of synthetic heterosite−purpurite, (MnyFe1-y)PO4 (y < 0.8), with negligible disorder and impurities, was obtained by chemical oxidation of the well-crystallized isotypic tryphillite−lithiophilite series, Li(MnyFe1-y)PO4 (ordered olivine structure, space group Pnma). Comparative magnetic and X-ray/neutron powder diffraction investigations of the two solid−solution lines were performed as a function of Mn content to increase understanding of the electrochemical activity loss of Mn3+/Mn2+ in the Lix(MnyFe1-y)PO4 electrode system. Introducing Mn ions into the 4c site did not cause significant change in the local geometry of M2+O6 and PO4 polyhedra, while the M3+O6 octahedra became severely distorted with an increase in the number of Jahn−Teller active Mn3+ ions. The edge-sharing geometry of M3+O6 and PO4 polyhedra fixed the shared O3‘−O3‘ interatomic distance, causing selective strong elongation of the M3+−O3‘ distance with small shrinkage of other M3+−O1, M3+−O2, and M3+−O3 bond lengths. The overall...

We report here the synthesis of single-phase bulk samples of CoO2, the x = 0 end member of the AxCoO2 systems (A = Li, Na), from a pristine LiCoO2 sample using an electrochemical technique to completely de-intercalate lithium. Thus, synthesized CoO2 samples were found to be oxygen-stoichiometric and possess a crystal structure consisting of stacked triangular-lattice CoO2 layers only. The magnetic susceptibility of the CoO2 sample was revealed to be relatively large in its initial value and then level off as the temperature increases, suggesting that CoO2 is a Pauli-paramagnetic metal with itinerant electrons., Comment: 18 pages, 5 figures