A deeper understanding of the relationships among composition–structure–transport properties in inorganic solid ionic conductors is of paramount importance to develop highly conductive phases for future employment in solid-state Li-ion battery applications. To shed light on the mechanisms that regulate these relationships, in this work, we perform a “two-dimensional” substitution series in the thio-LISICON family Li4Ge1–x Sn x S4–y Se y . The structural modifications brought up by the elemental substitutions were investigated via Rietveld refinements against high-resolution neutron diffraction data that allowed a precise characterization of the anionic framework and lithium substructure. The analyses show that the anionic and cationic substitutions influence the polyhedral and unit cell volumes in different fashions and that the size of the polyanionic groups alone is not enough to describe lattice expansion in these materials. Moreover, we show that the lithium disorder that is crucial to achieve fast ionic mobility may be correlated to the lithium polyhedral volumes. The correlation of these structural modifications with the transport properties, investigated via electrochemical impedance spectroscopy and 7Li nuclear magnetic resonance spin-lattice relaxation measurements, shows a nonmonotonic behavior of the ionic conductivity and activation energy against the lithium polyhedral volumes, hinting to an optimal size of the conduction pathways for the ionic diffusion. Ultimately, the results obtained in this work will help to establish new guidelines for the optimization of solid electrolytes and gain a more profound understanding of the influence of the substituents on the structure and transport properties of Li-ion conductors.

A deeper understanding of the relationships among composition‒structure‒transport properties in inorganic solid ionic conductors is of paramount importance to develop highly conductive phases for future employment in solid‒state Li‒ion battery applications. In order to shed light on the mechanisms that regulate these relationships, in this work we perform a “<i>two-dimensional</i>” substitution series in the thio-LISICON family Li₄Ge_1‒<i>x</i>Sn<i>_x</i>S_4‒<i>y</i>Se<i>_y</i>. The structural modifications brought up by the elemental substitutions were investigated via Rietveld refinements against high‒resolution neutron diffraction data that allowed a precise characterization of the anionic framework and the lithium substructure. The analyses show that the anionic and cationic substitutions influence the polyhedral and unit cell volumes in different fashions and that the size of the polyanionic groups alone is not enough to describe lattice expansion in these materials. Moreover, we show that the lithium disorder that is crucial to achieve fast ionic mobility may be correlated to the lithium polyhedral volumes. The correlation of these structural modifications with the transport properties, investigated via electrochemical impedance spectroscopy and ⁷Li nuclear magnetic resonance spin-lattice relaxation measurements, shows a non-monotonic behavior of the ionic conductivity and activation energy against the lithium polyhedral volumes, hinting to an optimal size of the conduction pathways for the ionic diffusion. Ultimately, the results obtained in this work will help to establish new guidelines for the optimization of solid electrolytes and to gain a more profound understanding of the influence of the substituents on the structure and transport properties of Li‒ion conductors

The wide interest in developing green energy technologies stimulates the scientific community to seek, for devices, new substitute material platforms with a low environmental impact, ease of production and processing and long-term stability. The synthesis of metal oxide (MO) semiconductors fulfils these requirements and efforts are addressed towards optimizing their functional properties through the improvement of charge mobility or energy level alignment. Two MOs have rising perspectives for application in light harvesting devices, mainly for the role of charge selective layers but also as light absorbers, namely MoO3 (an electron blocking layer) and Co3O4 (a small band gap semiconductor). The need to achieve better charge transport has prompted us to explore strategies for the doping of MoO3 and Co3O4 with vanadium (V) ions that, when combined with oxygen in V2O5, produce a high work function MO. We report on subcritical hydrothermal synthesis of V-doped mesostructures of MoO3 and of Co3O4, in which a tight control of the doping is exerted by tuning the relative amounts of reactants. We accomplished a full analytical characterization of these V-doped MOs that unambiguously demonstrates the incorporation of the vanadium ions in the host material, as well as the effects on the optical properties and work function. We foresee a promising future use of these materials as charge selective materials in energy devices based on multilayer structures.

A deeper understanding of the relationships among composition‒structure‒transport properties in inorganic solid ionic conductors is of paramount importance to develop highly conductive phases for future employment in solid‒state Li‒ion battery applications. In order to shed light on the mechanisms that regulate these relationships, in this work we perform a “<i>two-dimensional</i>” substitution series in the thio-LISICON family Li₄Ge_1‒<i>x</i>Sn<i>_x</i>S_4‒<i>y</i>Se<i>_y</i>. The structural modifications brought up by the elemental substitutions were investigated via Rietveld refinements against high‒resolution neutron diffraction data that allowed a precise characterization of the anionic framework and the lithium substructure. The analyses show that the anionic and cationic substitutions influence the polyhedral and unit cell volumes in different fashions and that the size of the polyanionic groups alone is not enough to describe lattice expansion in these materials. Moreover, we show that the lithium disorder that is crucial to achieve fast ionic mobility may be correlated to the lithium polyhedral volumes. The correlation of these structural modifications with the transport properties, investigated via electrochemical impedance spectroscopy and ⁷Li nuclear magnetic resonance spin-lattice relaxation measurements, shows a non-monotonic behavior of the ionic conductivity and activation energy against the lithium polyhedral volumes, hinting to an optimal size of the conduction pathways for the ionic diffusion. Ultimately, the results obtained in this work will help to establish new guidelines for the optimization of solid electrolytes and to gain a more profound understanding of the influence of the substituents on the structure and transport properties of Li‒ion conductors