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Prussian blue analogues (PBAs) are appealing active materials for post-lithium electrochemical energy storage. However, PBAs are not generally suitable for non-aqueous Li-ion storage due to their instability upon prolonged cycling. Herein, we assess the feasibility of PBAs with various lithium content for non-aqueous Li-ion storage. We determine the crystal structure of the lithiated PBAs via neutron powder diffraction measurements and investigate the influence of water on structural stability and Li-ion migration through operando X-ray diffraction measurements and bond valence simulations. Furthermore, we demonstrate that a positive electrode containing Li 2-x FeFe(CN) 6 ⋅nH 2 O (0 ≤ x ≤ 2) active material coupled with a Li metal electrode and a LiPF 6 -containing organic-based electrolyte in coin cell configuration delivers an initial discharge capacity of 142 mAh g −1 at 19 mA g −1 and a discharge capacity retention of 80.7% after 1000 cycles at 1.9 A g −1 . By replacing the lithium metal with a graphite-based negative electrode, we also report a coin cell capable of cycling for more than 370 cycles at 190 mA g −1 with a stable discharge capacity of about 105 mAh g −1 and a discharge capacity retention of 98% at 25 °C. Prussian blue analogues (PBAs) are appealing materials for aqueous Na- and K- ion batteries but are limited for non-aqueous Li-ion storage. Here, the authors report the synthesis of various lithiated PBAs and discuss critical factors for improving the non-aqueous electrochemical storage of Li ions.

Sodium ion batteries, because of their sustainability attributes, could be an attractive alternative to Li-ion technology for specific applications. However, it remains challenging to design high energy density and moisture stable Na-based positive electrodes. Here, we report an O3-type NaLi 1/3 Mn 2/3 O 2 phase showing anionic redox activity, obtained through a ceramic process by carefully adjusting synthesis conditions and stoichiometry. This phase shows a sustained reversible capacity of 190 mAh g −1 that is rooted in cumulative oxygen and manganese redox processes as deduced by combined spectroscopy techniques. Unlike many other anionic redox layered oxides so far reported, O3-NaLi 1/3 Mn 2/3 O 2 electrodes do not show discernible voltage fade on cycling. This finding, rationalized by density functional theory, sheds light on the role of inter- versus intralayer 3 d cationic migration in ruling voltage fade in anionic redox electrodes. Another practical asset of this material stems from its moisture stability, hence facilitating its handling and electrode processing. Overall, this work offers future directions towards designing highly performing sodium electrodes for advanced Na-ion batteries. Sodium ion batteries could be an attractive alternative to Li-ion technology but designing high energy density and moisture stable Na-based cathodes is challenging. Adjusting synthesis conditions and stoichiometry, an O3-type NaLi 1/3 Mn 2/3 O 2 phase with anionic redox activity is reported.

Most P2-type layered oxides exhibit Na + /vacancy-ordered superstructures because of strong Na + –Na + interaction in the alkali metal layer and charge ordering in the transition metal layer. These superstructures evidenced by voltage plateaus in the electrochemical curves limit the Na + ion transport kinetics and cycle performance in rechargeable batteries. Here we show that such Na + /vacancy ordering can be avoided by choosing the transition metal ions with similar ionic radii and different redox potentials, for example, Cr 3+ and Ti 4+ . The designed P2-Na 0.6 [Cr 0.6 Ti 0.4 ]O 2 is completely Na + /vacancy-disordered at any sodium content and displays excellent rate capability and long cycle life. A symmetric sodium-ion battery using the same P2-Na 0.6 [Cr 0.6 Ti 0.4 ]O 2 electrode delivers 75% of the initial capacity at 12C rate. Our contribution demonstrates that the approach of preventing Na + /vacancy ordering by breaking charge ordering in the transition metal layer opens a simple way to design disordered electrode materials with high power density and long cycle life. Sodium-containing layered oxides are promising battery cathodes, but their performance suffers from the formation of sodium ion-vacancy ordered superstructures. Here, the authors present a P2-Na 0.6 [Cr 0.6 Ti 0.4 ]O 2 layered oxide with disordered cations, leading to high battery performance.

The dependence on lithium-ion batteries leads to a pressing demand for advanced cathode materials. We demonstrate a new concept of layered-rocksalt intergrown structure that harnesses the combined figures of merit from each phase, including high capacity of layered and rocksalt phases, good kinetics of layered oxide and structural advantage of rocksalt. Based on this concept, lithium nickel ruthenium oxide of a main layered structure ( R 3 ¯ m ) with intergrown rocksalt ( Fm 3 ¯ m ) is developed, which delivers a high capacity with good rate performance. The interwoven rocksalt structure successfully prevents the anisotropic structural change that is typical for layered oxide, enabling a nearly zero-strain operation upon high-capacity cycling. Furthermore, a design principle is successfully extrapolated and experimentally verified in a series of compositions. Here, we show the success of such layered-rocksalt intergrown structure exemplifies a new battery electrode design concept and opens up a vast space of compositions to develop high-performance intergrown cathode materials. The dependence on lithium-ion batteries leads to a pressing demand for advanced cathode materials. Here the authors report a new concept of layered-rocksalt intergrown structure that enables nearly zero-strain operation upon high-capacity cycling, offering tremendous opportunities to design new cathodes.

The combination of a materials database with high-throughput ion-transport calculations is an effective approach to screen for promising solid electrolytes. However, automating the complicated preprocessing involved in currently widely used ion-transport characterization algorithms, such as the first-principles nudged elastic band (FP-NEB) method, remains challenging. Here, we report on high-throughput screening platform for solid electrolytes (SPSE) that integrates a materials database with hierarchical ion-transport calculations realized by implementing empirical algorithms to assist in FP-NEB completing automatic calculation. We first preliminarily screen candidates and determine the approximate ion-transport paths using empirical both geometric analysis and the bond valence site energy method. A chain of images are then automatically generated along these paths for accurate FP-NEB calculation. In addition, an open web interface is actualized to enable access to the SPSE database, thereby facilitating machine learning. This interactive platform provides a workflow toward high-throughput screening for future discovery and design of promising solid electrolytes and the SPSE database is based on the FAIR principles for the benefit of the broad research community.

Low thermal conductivity is favorable for preserving the temperature gradient between the two ends of a thermoelectric material, in order to ensure continuous electron current generation. In high-performance thermoelectric materials, there are two main low thermal conductivity mechanisms: the phonon anharmonic in PbTe and SnSe, and phonon scattering resulting from the dynamic disorder in AgCrSe 2 and CuCrSe 2 , which have been successfully revealed by inelastic neutron scattering. Using neutron scattering and ab initio calculations, we report here a mechanism of static local structure distortion combined with phonon-anharmonic-induced ultralow lattice thermal conductivity in α -MgAgSb. Since the transverse acoustic phonons are almost fully scattered by the compound’s intrinsic distorted rocksalt sublattice, the heat is mainly transported by the longitudinal acoustic phonons. The ultralow thermal conductivity in α -MgAgSb is attributed to its atomic dynamics being altered by the structure distortion, which presents a possible microscopic route to enhance the performance of similar thermoelectric materials. In order to optimize thermoelectric (TE) materials which are used to convert thermal energy and electrical energy, the underlying physics needs to be understood. Here, the authors show that by exploiting static local structure distortion, transverse acoustic phonons can be suppressed resulting in high performing TE materials.

Stable solid electrolytes are essential to high-safety and high-energy-density lithium batteries, especially for applications with high-voltage cathodes. In such conditions, solid electrolytes may experience severe oxidation, decomposition, and deactivation during charging at high voltages, leading to inadequate cycling performance and even cell failure. Here, we address the high-voltage limitation of halide solid electrolytes by introducing local lattice distortion to confine the distribution of Cl − , which effectively curbs kinetics of their oxidation. The confinement is realized by substituting In with multiple elements in Li 3 InCl 6 to give a high-entropy Li 2.75 Y 0.16 Er 0.16 Yb 0.16 In 0.25 Zr 0.25 Cl 6 . Meanwhile, the lattice distortion promotes longer Li-Cl bonds, facilitating favorable activation of Li + . Our results show that this high-entropy halide electrolyte boosts the cycle stability of all-solid-state battery by 250% improvement over 500 cycles. In particular, the cell provides a higher discharge capacity of 185 mAh g −1 by increasing the charge cut-off voltage to 4.6 V at a small current rate of 0.2 C, which is more challenging to electrolytes|cathode stability. These findings deepen our understanding of high-entropy materials, advancing their use in energy-related applications. Solid electrolytes play a crucial role as ion conductors and separator between electrodes in all-solid-state batteries. Here, the authors report a high-entropy halide solid electrolyte, which reveals the structure evolution with the increasing configurational entropy and improves the high-voltage stability.

Dimensionality is a critical factor in determining the properties of solids and is an apparent built-in character of the crystal structure. However, it can be an emergent and tunable property in geometrically frustrated spin systems. Here, we study the spin dynamics of the tetrahedral cluster antiferromagnet, pharmacosiderite, via muon spin resonance and neutron scattering. We find that the spin correlation exhibits a two-dimensional characteristic despite the isotropic connectivity of tetrahedral clusters made of spin 5/2 Fe 3+ ions in the three-dimensional cubic crystal, which we ascribe to two-dimensionalisation by geometrical frustration based on spin wave calculations. Moreover, we suggest that even one-dimensionalisation occurs in the decoupled layers, generating low-energy and one-dimensional excitation modes, causing large spin fluctuation in the classical spin system. Pharmacosiderite facilitates studying the emergence of low-dimensionality and manipulating anisotropic responses arising from the dimensionality using an external magnetic field. Dimensionality reduction can occur in magnetically frustrated systems; however, it typically involves lattice distortions. Here, the authors report two- and one-dimensional character of spin correlations in a three-dimensional tetrahedral cluster antiferromagnet, driven purely by geometrical frustration.

We have synthesized a new intermetallic compound Ho 2 Ni 0.95 Si 2.95 in a single phase with a defect crystal structure. The magnetic ground state of this material found to be highly frustrated without any long range order or glassy feature as investigated through magnetic, heat capacity and neutron diffraction measurements. The interest in this material stems from the fact that despite the absence of true long range order, large magnetocaloric effect (isothermal magnetic entropy change, −ΔS M  ~ 28.65 J/Kg K (~205.78 mJ/cm 3  K), relative cooling power, RCP ~ 696 J/Kg (~5 J/cm 3 ) and adiabatic temperature change, ΔT ad  ~ 9.32 K for a field change of 70 kOe) has been observed which is rather hard to find in nature.

The triangular lattice antiferromagnet (TLAF) has been the standard paradigm of frustrated magnetism for several decades. The most common magnetic ordering in insulating TLAFs is the 120° structure. However, a new triple- Q chiral ordering can emerge in metallic TLAFs, representing the short wavelength limit of magnetic skyrmion crystals. We report the metallic TLAF Co 1/3 TaS 2 as the first example of tetrahedral triple- Q magnetic ordering with the associated topological Hall effect (non-zero σ xy ( H  = 0)). We also present a theoretical framework that describes the emergence of this magnetic ground state, which is further supported by the electronic structure measured by angle-resolved photoemission spectroscopy. Additionally, our measurements of the inelastic neutron scattering cross section are consistent with the calculated dynamical structure factor of the tetrahedral triple- Q state. Skyrmion crystals, where skyrmions are arranged close packed in a triangular lattice arise due to the superposition of three magnetic spin spirals, each with a distinct wave vector, Q. Such skrymion crystals have been found in a diverse array of materials. Here, Park et al find a short wavelength (or dense skyrmion) limit of this skyrmion crystal structure in Co1/3TaS2, a metallic triangular lattice antiferromagnet, in the form of a triple Q magnetic ordering, with four magnetic sublattices.’