Rechargeable all‐solid‐state lithium Li‐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. AS‐LIBs require a Li‐fast ion conductor (FIC) as the solid electrolyte. Finding a solid electrolyte with high ionic conductivity and compatibility with other battery components is a key factor in building high performance AS‐LIBs. There have been numerous studies, e.g., on lithium rich sulfide glasses as solid electrolytes. However, the limited current density remains a major obstacle in developing competitive batteries based on the known solid electrolytes. Here we prepare argyrodite‐type Li6PS5X (X = Cl, Br, I) using mechanical milling followed by annealing. XRD characterization reveals the formation and growth of Li6PS5X crystals in samples under varying annealing conditions. For Li6PS5Cl an ionic conductivity of the order of 10−4 S/cm is reached at room temperature, which is close to the Li mobility in conventional liquid electrolytes (LiPF6 in various carbonates) and well suitable for AS‐LIBs.

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Empirical bond length-bond valence (BV) relations provide insight into the link between structure of and ion transport in solid electrolytes and mixed conductors. Building on our earlier systematic adjustment of BV parameters to the bond softness, here we discuss how the squared BV mismatch is linked to the absolute energy scale and used as a general Morse-type interaction potential for analyzing low-energy ion migration paths in ion conducting solids or mixed conductors by either an energy landscape approach or molecular dynamics (MD) simulations. For a wide range of lithium oxides we could thus model ion transport revealing significant differences to an earlier geometric approach. This novel BV-based force-field has then been applied to investigate a range of mixed conductors, focusing on cathode materials for lithium ion battery (LIB) applications to promote a systematic design of LIB cathodes that combine high energy density with high power density. To demonstrate the versatility of the new BV-based force field it is applied in exploring various strategies to enhance the power performance of safe low cost LIB materials including

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Structure-property relationships provide valuable guidelines for a systematic development of functional materials. Here an augmented bond-valence approach is worked out that is linked directly to the energy scale. This energy-scaled bond-valence approach is then used to identify ion-conduction pathways and to establish structure-property relationships in complex disordered solids using lithium silicate glasses as model systems. Representative local structure models of glassy solid electrolytes as a basis for the pathway analysis are derived from molecular dynamics simulations. Predictions of the bond-valence model from a static structure model are compared to a complete trajectory analysis, showing a high degree of agreement. The method yields consistent results when changing the simulation force field and is applicable to a wide range of glasses.

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The favorable combination of fast-ionic conductivity and high electrochemical stability of Li-stuffed garnet type Li 7 La 3 Zr 2 O 12 (LLZ) makes this material a promising candidate for applications as a solid-state electrolyte in high-energy-density batteries. However, a widespread technical use of LLZ is impeded by difficulty in reliable formation and densification of the pure fast-ion conducting phase. The present study of the phase-formation process enables rational fabrication procedures to be devised based on a thorough understanding of the complex phase formation of LLZ. In situ neutron powder diffraction monitoring of the phase formation revealed an influence of the partial melting of precursors on the formation of the fast-ion conducting phase, indicating that in the typical synthesis route LLZ is not formed in a solid-state reaction but from a partial carbonate melt that decomposes on further heating. The cooling rate critically influences lithium ordering and ionic conductivity.

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