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Ge4+ substitution into the recently discovered superionic conductor Li7Si2S7I is demonstrated by synthesis of Li7Si2–xGexS7I, where x≤1.2. The anion packing and tetrahedral silicon location of Li7Si2S7I are retained upon substitution. Single crystal X‐ray diffraction shows that substitution of larger Ge4+ for Si4+ expands the unit cell volume and further increases Li+ site disorder, such that Li7Si0.88Ge1.12S7I has one Li+ site more (sixteen in total) than Li7Si2S7I. The ionic conductivity of Li7Si0.8Ge1.2S7I (x=1.2) at 303 K is 1.02(3)×10−2 S cm−1 with low activation energies for Li+ transport demonstrated over a wide temperature range by AC impedance and 7Li NMR spectroscopy. All sixteen Li+ sites remain occupied to temperatures as low as 30 K in Li7Si0.88Ge1.12S7I as a result of the structural expansion. This differs from Li7Si2S7I, where the partial Li+ site ordering observed below room temperature reduces the ionic conductivity. The suppression of Li+ site depopulation by Ge4+ substitution retains the high mobility to temperatures as low as 200 K, yielding low temperature performance comparable with state‐of‐the‐art Li+ ion conducting materials. [ABSTRACT FROM AUTHOR]

Magnesium batteries attract interest as alternative energy‐storage devices because of elemental abundance and potential for high energy density. Development is limited by the absence of suitable cathodes, associated with poor diffusion kinetics resulting from strong interactions between Mg2+ and the host structure. V2PS10 is reported as a positive electrode material for rechargeable magnesium batteries. Cyclable capacity of 100 mAh g−1 is achieved with fast Mg2+ diffusion of 7.2× ${\times }$ 10−11–4× ${\times }$ 10−14 cm2 s−1. The fast insertion mechanism results from combined cationic redox on the V site and anionic redox on the (S2)2− site; enabled by reversible cleavage of S−S bonds, identified by X‐ray photoelectron and X‐ray absorption spectroscopy. Detailed structural characterisation with maximum entropy method analysis, supported by density functional theory and projected density of states analysis, reveals that the sulphur species involved in anion redox are not connected to the transition metal centres, spatially separating the two redox processes. This facilitates fast and reversible Mg insertion in which the nature of the redox process depends on the cation insertion site, creating a synergy between the occupancy of specific Mg sites and the location of the electrons transferred. [ABSTRACT FROM AUTHOR]

Halogen-based redox-active materials represent an important class of materials in aqueous electrochemistry. The existence of versatile halogen species and their rich bonding coordination create great flexibility in designing new redox couples. Novel redox reaction mechanisms and electrochemical reversibility can be unlocked in specifically configurated electrolyte environments and electrodes. In this review, the halogen-based redox couples and their appealing redox chemistries in aqueous batteries, including redox flow batteries and traditional static batteries, that have been studied in recent years are discussed. New aqueous electrochemistry provides hope to outperform the state-of-the-art materials and systems that are facing resources and performance limitation, and to enrich the existing battery chemistries., (© 2024 Wiley‐VCH GmbH.)

Ge 4+ substitution into the recently discovered superionic conductor Li 7 Si 2 S 7 I is demonstrated by synthesis of Li 7 Si 2-x Ge x S 7 I, where x≤1.2. The anion packing and tetrahedral silicon location of Li 7 Si 2 S 7 I are retained upon substitution. Single crystal X-ray diffraction shows that substitution of larger Ge 4+ for Si 4+ expands the unit cell volume and further increases Li + site disorder, such that Li 7 Si 0.88 Ge 1.12 S 7 I has one Li + site more (sixteen in total) than Li 7 Si 2 S 7 I. The ionic conductivity of Li 7 Si 0.8 Ge 1.2 S 7 I (x=1.2) at 303 K is 1.02(3)×10 -2  S cm -1 with low activation energies for Li + transport demonstrated over a wide temperature range by AC impedance and 7 Li NMR spectroscopy. All sixteen Li + sites remain occupied to temperatures as low as 30 K in Li 7 Si 0.88 Ge 1.12 S 7 I as a result of the structural expansion. This differs from Li 7 Si 2 S 7 I, where the partial Li + site ordering observed below room temperature reduces the ionic conductivity. The suppression of Li + site depopulation by Ge 4+ substitution retains the high mobility to temperatures as low as 200 K, yielding low temperature performance comparable with state-of-the-art Li + ion conducting materials., (© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Magnesium batteries attract interest as alternative energy-storage devices because of elemental abundance and potential for high energy density. Development is limited by the absence of suitable cathodes, associated with poor diffusion kinetics resulting from strong interactions between Mg 2+ and the host structure. V 2 PS 10 is reported as a positive electrode material for rechargeable magnesium batteries. Cyclable capacity of 100 mAh g -1 is achieved with fast Mg 2+ diffusion of 7.2 × ${\times }$ 10 -11 -4 × ${\times }$ 10 -14  cm 2  s -1 . The fast insertion mechanism results from combined cationic redox on the V site and anionic redox on the (S 2 ) 2- site; enabled by reversible cleavage of S-S bonds, identified by X-ray photoelectron and X-ray absorption spectroscopy. Detailed structural characterisation with maximum entropy method analysis, supported by density functional theory and projected density of states analysis, reveals that the sulphur species involved in anion redox are not connected to the transition metal centres, spatially separating the two redox processes. This facilitates fast and reversible Mg insertion in which the nature of the redox process depends on the cation insertion site, creating a synergy between the occupancy of specific Mg sites and the location of the electrons transferred., (© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)