Most solid-state materials are composed of p-block anions, only in recent years the introduction of hydride anions (1s2) in oxides (e.g., SrVO2H, BaTi(O,H)3) has allowed the discovery of various interesting properties. Here we exploit the large polarizability of hydride anions (H–) together with chalcogenide (Ch2–) anions to construct a family of antiperovskites with soft anionic sublattices. The M3HCh antiperovskites (M = Li, Na) adopt the ideal cubic structure except orthorhombic Na3HS, despite the large variation in sizes of M and Ch. This unconventional robustness of cubic phase mainly originates from the large size-flexibility of the H– anion. Theoretical and experimental studies reveal low migration barriers for Li+/Na+ transport and high ionic conductivity, possibly promoted by a soft phonon mode associated with the rotational motion of HM6 octahedra in their cubic forms. Aliovalent substitution to create vacancies has further enhanced ionic conductivities of this series of antiperovskites, resulting in Na2.9H(Se0.9I0.1) achieving a high conductivity of ~1 × 10–4 S/cm (100 °C).

An efficient and selective catalyst is in urgent need for carbon dioxide electroreduction and silver is one of the promising candidates with affordable costs. Here we fabricated large-scale vertically standing Ag nanowire arrays with high crystallinity and electrical conductivity as carbon dioxide electroreduction catalysts by a simple nanomolding method that was usually considered not feasible for metallic crystalline materials. A great enhancement of current densities and selectivity for CO at moderate potentials was achieved. The current density for CO ( j) of Ag nanowire array with 200 nm in diameter was more than 2500 times larger than that of Ag foil at an overpotential of 0.49 V with an efficiency over 90%. The origin of enhanced performances are attributed to greatly increased electrochemically active surface area (ECSA) and higher intrinsic activity compared to those of polycrystalline Ag foil. More low-coordinated sites on the nanowires which can stabilize the CO intermediate better are responsible for the high intrinsic activity. In addition, the impact of surface morphology that induces limited mass transportation on reaction selectivity and efficiency of nanowire arrays with different diameters was also discussed.

and sustainable society; however, LIBs are facing bottlenecks in terms of energy/ power density and safety. [1,2] In recent decades, many new concepts for batteries have been proposed as potential alternatives for LIBs, such as battery systems that employ Na + , K + , Mg 2+ , Zn 2+ , Ca 2+ , Al 3+ , F − , or Cl − as charge carriers, which have significantly expanded the strategies for developing next-generation batteries with high energy and power densities. [3,4] All-solid-state fluoride-ion batteries (FIBs) have received widespread attention because of the high electronegativity of fluorine. This leads to extraordinary anodic electrochemical stability, resulting in superior reliability for solid-state utilization. In early studies, including our recent ones, simple metal/metal fluoride (M/MF x ) systems were first used as electrode materials with high theoretical capacities. [3,[5][6][7][8][9] Using M/MF x systems, it is theoretically feasible to fabricate batteries with high energy densities because the working potential can exceed 3 V if suitable cathode-anode combinations are selected. However, closepacked metal atoms (e.g., Cu, Co, Ni, and Bi) provide no diffusion path for F anions in conversion-type M/MF x systems; as a result, M/MF x systems inevitably suffer from thorough atomic rearrangements and undesired volumetric changes upon All-solid-state fluoride-ion batteries (FIBs) are regarded as promising energy storage devices; however, currently proposed cathodes fail to meet the requirements for practical applications in terms of high energy density and high rate capability. Herein, the first use of stable and low-cost cuprous oxide (Cu 2 O) as a cathode material for all-solid-state FIBs with reversible and fast (de)fluorination behavior is reported. A phase-transition reaction mechanism involving Cu + /Cu 2+ redox for charge compensation is confirmed, using the combination of electrochemical methods and X-ray absorption spectroscopy. The first discharge capacity is approximately 220 mAh g −1 , and fast capacity fading is observed in the first five cycles, which is ascribed to partial structural amorphization. Compared with those of simple metal/metal fluoride systems, the material shows a superior rate capability, with a first discharge capacity of 110 mAh g −1 at 1 C. The rate-determining step and probable structural evolutions are investigated as well. It is believed that the comprehensive investigations of Cu 2 O as a cathode material described in this work can lead to an improved understanding of all-solid-state FIBs.

Fe-based multiphase nanocrystallized ribbons (CR-II) prepared by annealing of metallic glasses show unexpected high performance for Orange II degradation.

To improve ionic conductivity, solid-state electrolytes with polarizable anions that weakly interact with mobile ions have received much attention, a recent example being lithium/sodium-rich antiperovskite M3HCh (M = Li, Na; Ch = S, Se, Te). Herein, in order to clarify the role of anions in antiperovskites, the M3FCh family, in which the polarizable H– anion at the octahedral center is replaced by the ionic F– anion, is investigated theoretically and experimentally. We unexpectedly found that the stronger attractive interaction between F– and M+ ions does not slow down the M+ ion diffusion, with the calculated energy barrier being as low as that of M3HCh. This fact suggests that the low-frequency rotational phonon modes of the octahedron of cubic M3FCh (and M3HCh) are intrinsic to facilitate the fast ionic diffusion. A systematic analysis further reveals a correlation between the tolerance factor t and the ionic transport: as t decreases within the cubic phase, the rotational mode becomes softer, resulting in the reduction of the migration energy. The cubic iodine-doped Li3FSe has a room-temperature ionic conductivity of 5 × 10–5 S/cm with a bulk activation energy of 0.18 eV.