Wadsley–Roth oxides are promising negative electrode materials for fast-charging Li-ion batteries, yet the role of secondary cations in these niobium-based crystal frameworks remains insufficiently understood. Here, we investigate the impact of controlled multicationic substitution within the Nb12O29 framework through the design of new isostructural compositions with increasing chemical complexity. Two compositions containing three and six secondary cations, respectively Ti2/3Fe1/3Ga1/3Nb32/3O29 and Al1/6Ti1/3Cr1/6Fe1/6Co1/6Ga1/6Nb65/6O29, were successfully synthesized by a conventional solid-state route. Electrochemical measurements reveal enhanced capacity retention over an extended current-density range for the former composition, whereas the latter exhibits performance comparable to those of the compounds Ti2Nb10O29, FeNb11O29 and GaNb11O29. Operando synchrotron X-ray powder diffraction and galvanostatic intermittent titration analyses indicate that lithium insertion proceeds through similar structural and electrochemical mechanisms across all investigated compositions. These results indicate that moderate multicationic substitution can improve electrochemical performance without altering the fundamental lithium-storage mechanism, whereas further increases in chemical complexity do not necessarily translate into additional gains and may be accompanied by increased compositional heterogeneity. More broadly, this study provides a critical experimental assessment of compositionally complex design strategies in Wadsley–Roth oxides, suggesting that the benefits often associated with high-entropy approaches should be evaluated alongside the specific chemical nature of the incorporated cations rather than solely through the degree of cationic complexity.

P2-type layered sodium transition-metal oxides are promising high-energy cathodes for sodium-ion batteries but suffer from structural degradation and irreversible redox reactions particularly in the high-voltage region, resulting in rapid capacity fade. This study investigates how Cu substitution affects the structural evolution, redox mechanisms, and electrochemical performance of P2-type Na2/3Mn2/3Ni1/3-yCuyO2 (y = 0, 1/6, 1/3) cathodes for sodium-ion batteries. Cu substitution not only raises the average voltage of the practically delivered capacity upon extended cycling, thereby increasing energy density, but also shifts the undesired high-voltage plateau, associated with irreversible Ni4+/Ni3+ and/or oxygen redox, to potentials beyond the practical operating window. This enables the partially substituted Na2/3Mn2/3Ni1/6Cu1/6O2 to deliver 94.8 mAh g-1 at an average voltage of 3.45 V (320 Wh kg-1) with 92% capacity retention after 100 cycles in half cells. Operando synchrotron X-ray diffraction reveals that this enhanced stability arises from a distinct phase evolution: while Na2/3Mn2/3Ni1/3O2 develops a P2 to O2 transition together with a loss of crystallinity in the form of stacking faults, the partially Cu-substituted sample forms a more reversible OP4 structure above 4.0 V with less pronounced interlayer-spacing changes. Operando X-ray absorption reveals sequential Ni2+ and Cu2+ oxidation to Ni3+ and Cu3+, respectively. Extended X-ray absorption fine structure (EXAFS) analysis, corroborated by density functional theory (DFT) calculations, shows that in Na2/3Mn2/3Ni1/6Cu1/6O2 NiO6 and CuO6 octahedra undergo almost-simultaneous opposite Jahn-Teller-distortion trends. This phenomenon reduces the effective overall Jahn-Teller-related lattice strain during (de)sodiation, compared to Na2/3Mn2/3Ni1/3O2 and Na2/3Mn2/3Cu1/3O2. Full-cell tests vs. hard carbon demonstrate the practical relevance, with Na2/3Mn2/3Ni1/6Cu1/6O2 retaining 80% of its initial energy after 310 cycles and 50% after 1130 cycles at 100 mA g-1, establishing partial Cu substitution as an effective route to stabilize high-voltage P2-type layered oxides for durable sodium-ion batteries.

ABSTRACT Solid‐state batteries are widely regarded as the future of electrochemical energy storage; however, their progress is impeded by unresolved chemical and mechanical challenges related to the electrolyte composition preparation. Hybrid electrolytes (HE), produced by combining non‐conductive polymers with thiophosphates, are theoretically anticipated to enhance mechanical strength. The impact of polymer additives on thiophosphate characteristics—such as stability range and ionic conductivity—remains insufficiently understood. In this investigation, a small quantity of PVDF based polymer was manually blended with Li6PS5Cl solid electrolyte at ambient temperature via a dry process. Advanced multi‐scale characterization techniques revealed that the addition of minimal binder preserves high ionic conductivity and maintains a favourable electrochemical stability window, while simultaneously improving material toughness (evidenced by decreased dendrite growth and enhanced interface stability). Nevertheless, intimate mixing of these components induces surface chemical reactions, as demonstrated through comprehensive X‐ray diffraction and X‐ray photoemission spectroscopy.

Sodium all-solid-state batteries (Na-ASSBs) based on NASICON solid electrolytes are promising candidates for safe and cost-effective energy storage. Here, we investigate symmetric Na3V2(PO4)3 (N3.0VP) / Na3.4Zr2Si2.4P0.6O12 (N3.4ZSP) / Na3V2(PO4)3 (N3.0VP) cells assembled by spark plasma sintering to improve electrode - electrolyte contact. The cells deliver high capacities (107 mAh.g⁻¹ on charge, and 94 mAh.g⁻¹ on discharge at 200°C under a current density of 37.51 μA.cm−2, C/20) with extremely low polarization and good reversibility over the investigated cycles. Interestingly, instead of the expected single voltage plateau at ∼1.8 V, the cells exhibit two distinct redox features, as revealed by incremental capacity analysis. High-temperature operando synchrotron XRD at 120°C shows that no intermediate phases form on the cathode side, whereas the anode undergoes a solid-solution behaviour leading to the formation of a previously unreported ∼Na3.6V2(PO4)3 phase. These findings uncover an alternative reaction pathway responsible for the additional redox activity and provide new insights into the behaviour of NASICON based Na-ASSBs under high temperature conditions.

Direct recycling of lithium-ion battery cathodes offers a promising route to reduce the environmental and economic footprint of battery manufacturing.

Magnetic behavior across Fe_2O_3 polymorphs varies widely despite identical chemistry, highlighting crystal architecture as a key determinant of exchange topology, magnetic anisotropy, and ultimately magnetic order. Here, using neutron and synchrotron X-ray diffraction, we establish the magnetic ground state of the poorly understood bixbyite β-Fe_2O_3 polymorph and uncover the structural origin of its strong frustration. Below the Néel temperature, a noncollinear antiferromagnetic state emerges through activation of the mH_1^+ irrep at the H-point [𝐤=(1,1,1)] and the antitranslation (1'|12,12,12), breaking the body centering and yielding two interpenetrating primitive cubic magnetic subcells with inverted moments and nonpolar type-IV symmetry. Under exclusively antiferromagnetic Fe^3+-O-Fe^3+ interactions, β-Fe_2O_3 exhibits a large frustration index (f ≈ 7.56). This behavior originates from the intrinsic geometry of the bixbyite lattice: two magnetic sublattices with distinct point symmetries and anisotropy constraints are embedded in a three-dimensional exchange network containing interconnected triangular and hexagonal motifs. In {111} planes, Fe2 ions form hexagonal rings interconnected by frustrated triangular units, while locally Ising-like Fe1 ions occupy the ring centers. Our results thus identify the bixbyite architecture as a promising general platform for frustrated noncollinear magnetism. Extending this structural framework to other magnetic transition-metal or 4f ions opens a materials space for engineering competing exchange interactions and anisotropies, potentially stabilizing new noncollinear and field-tunable magnetic states.

Compositional tuning of Na x V 2 (PO 4 ) 3 high valent vanadium redox reveals a mechanism transition from biphasic to solid-solution behaviour.

ABSTRACT The electrochemical behavior of graphite anodes is strongly affected by structural disorder, yet graphite crystallinity is often described using averaged descriptors that do not resolve the underlying defect landscape. Here, we investigate a series of industrially relevant graphite samples combining high‑resolution synchrotron x‑ray diffraction with FAULTS‐based analysis of planar defects and operando measurements. We show that graphites with similar average crystallographic signatures span distinct defect‑topology regimes defined by different combinations of stacking faults, rhombohedral (3R) intergrowths and turbostratic interlayers. Operando diffraction reveals that lithium insertion does not initiate within an ideal 2H host, but proceeds preferentially through stacking‑faulted and 3R‑related environments, which provide structurally accessible insertion pathways. In contrast, turbostratic interlayers do not participate in early lithium insertion and correlate with reduced reversible capacity. These results demonstrate that graphite behavior is governed by defect topology rather than by a single degree of disorder and highlight the need for defect‑resolved structural descriptors to rationalize lithium intercalation mechanisms in graphite.

The cation disorder over the two crystallographic sites, M oct O 6 and M pyr O 5 , in the SmCr 1− x Fe x TiO 5 mullite-like structure is shown to be the main parameter that governs the magnetic ground state, from long range antiferromagnetism to spin glass.

Battery technology has become increasingly important in recent years due to the growing demand for portable electronic devices and electric vehicles, and to improve the performance and lifespan of batteries, it is essential to understand the complex processes that occur during their operation. NOTOS is one beamline at ALBA Synchrotron Light Source devoted to X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD), specifically designed to study the electronic structure and the short- and long-range crystal structure order in a wide range of scientific disciplines: chemistry, catalysis/electrocatalysis, energy science, nanomaterials, condensed matter and environmental science. Nowadays, the available photon source is a bending magnet and the operating energy range is 4.5–30 keV. However, in the framework of ALBA-II upgrade, NOTOS will extend its energy range to 35 keV and will get more photon flux at energies above 10 keV thanks to a new superconducting bending magnet. In addition to the capability to perform XAS and XRD investigations separately, the beamline allows quasi-simultaneous XAS–XRD experiments. This article aims to demonstrate the instrumental capabilities of NOTOS for operando electrochemical measurements of batteries.

Bi-doped copper (Cu1-xBix) nanowires (NWs), promising candidates for spintronic applications due to their potential for a giant spin Hall effect (SHE), were synthesized, and their structural properties and thermal stability were investigated. Using template-assisted electrodeposition, Cu1-xBix nanowires with varying bismuth (Bi) content (x = 0, 2, 4, and 7%) and different crystalline domain sizes were fabricated. Structural analysis by advanced electron microscopy and X-ray scattering techniques revealed the influence of synthesis conditions on the resulting NW crystal structure and microstructure, including Bi localization (within the lattice or in the grain boundaries), crystallite domain dimensions, and lattice distortions. While NWs with larger crystalline domains allow homogeneous Bi incorporation into the Cu lattice, NWs with smaller crystalline domains exhibit noticeable Bi accumulation at grain boundaries. The thermal stability of the NWs was examined using variable temperature X-ray diffraction and total scattering. Upon heating, lattice distortions consistent with Bi diffusion out of the Cu lattice were observed, with subsequent crystallization of rhombohedral metallic Bi upon cooling. Microstructural analysis of NWs post heating shows that the recrystallized rhombohedral Bi accumulates in localized regions within the NWs, most likely corresponding to grain boundaries. In some cases, the exsolution of Bi from these regions leads to wedge-shaped fractures in the NWs and the formation of independent Bi particles. These findings establish a foundation for optimizing the SHE performance of Cu1-xBix nanowires for spintronic devices by correlating synthesis parameters with microstructural features and thermal behavior.

Heteroatom-doping has emerged as a transformative approach to producing high-performance catalysts, yet the current trial-and-error approach to optimize these materials remains ineffective. To enable the rational design of more efficient catalysts, models grounded in a deeper understanding of catalytic mechanisms are essential. Existing models, such as d-band center theory, fall short in explaining the role of dopants, particularly when these dopants do not directly interact with reactants. In this study, we synthesize various heteroatom-doped catalysts to explore the correlation between the electronic effects of the dopants and catalyst activity. Using Co-MoS2 as a model catalyst and the Li-S redox reaction within the cathode of Li-S batteries as a test system, we show the interaction between cobalt sites and adjacent lattice sulfur atoms disrupts the intrinsic structural and electronic symmetry of MoS2. This disruption enhances the transfer of spin-polarized electrons from metal centers to lattice sulfur and promotes the adsorption of reactant intermediates. Furthermore, by analyzing 20 different dopant elements, we establish a linear relationship between the electron density in the lattice sulfur and catalyst activity toward the reduction of sulfur species, a relationship that extends to other catalytic systems, such as the hydrogen evolution reaction.

In this study, sodium- and lithium-based phosphate niobium bronzes and bronzoids with the general formula Ax(PO2)2(NbO3)m (where A = Na/Li and m = 4), specifically Na2Nb4P2O16 and Li2Nb4P2O16, are investigated. The crystal structure of Na2Nb4P2O16 is revisited using a combination of laboratory and synchrotron powder X-ray powder diffraction. It is found to crystallize in the P21/a space group (different from the previously reported P21 space group), with lattice parameters a = 13.2503 (6) Å, b = 5.3498 (2) Å, c = 19.0807 (7) Å, β = 109.9574 ° (3) and V/Z = 317.833 (9) Å3. Additionally, we synthesized and determined the crystal structure of Li2Nb4P2O16 for the first time, introducing it as a lithium-based phosphate niobium bronzoid. It crystallizes in the Pc21n orthorhombic cell with lattice constants a = 6.7031 (4) Å, b = 5.1936 (2) Å, c = 17.4260 (8) Å, and V/Z = 303.324 (5) Å3. As negative electrodes in Li batteries, Li2Nb4P2O16 and Na2Nb4P2O16 exhibited average discharge capacities of 386 and 277 mAh/g, respectively, at C/15 in a voltage window of 3.0-0.1 V.

YBaCuFeO5 and related compounds can sustain chiral magnetic order up to unexpectedly high temperatures. The underlying mechanism, governed by cation disorder, offers a promising route for the development of magnetoelectric spirals operable at ambient temperature. In addition, some chemical substitutions at the A or B sites allow upgrading the spiral stability and reducing significantly the required level of cation disorder in these layered perovskites. In this work, we have addressed the effects of simultaneous divalent substitution at the A and B sites, in Y(Ba,Sr)(Cu,Co)FeO5 samples synthesized with the same level of Fe/Cu disorder. This strategy combines the chemical pressure induced by the smaller A-site Sr ions with the reduced uniaxial elongation in the Cu pyramids induced by Co substitution. By enhancing frustration through chemical pressure, we investigated the evolution of the spiral order and its stability relative to other competing magnetic phases. Three distinct regions were identified as a function of Sr content, demonstrating a pronounced interplay between A- and B-site substitutions that substantially alters the phase diagrams obtained for single-site doping. In low-disorder Y(Ba1-xSrx)(Cu0.96Co0.04)FeO5, T-S1 approximate to 300 K for x <= 5%. At higher Sr concentrations, T-S1 decreases and the spiral order eventually disappears abruptly for x > 10%.

The temperature-composition structural phase diagram of the BTO-based ferroelectric system Ba0.94Ca0.06Ti1-xHfxO3 (0.05 <= x <= 0.15) is investigated using high-angular resolution synchrotron X-ray powder diffraction and dielectric permittivity measurements. In contrast to the well-known structural phase transition sequence of the parent compound BaTiO3 (rhombohedral -> orthorhombic -> tetragonal -> cubic, upon heating), Hf4+ doping into Ba0.94Ca0.06Ti1-xHfxO3 results in the gradual disappearance of the intermediate orthorhombic and tetragonal phases at two different, but close, critical concentrations, 0.10 < x(c1) < 0.12 and 0.12 < x(c2) < 0.135, respectively, revealing the presence of two triple points in the phase diagram.

The transition to renewable energy sources requires cost-effective and scalable energy storage solutions based on abundant elements, such as Na-ion batteries with sustainable positive electrode materials, based on Na, Fe, and S. The sulfate-based alluaudite Na2+2 delta Fe2-delta(SO4)3 that exhibits excellent cycling performance inspired the investigation of mixed PO4 3-/SO4 2- polyanion-based compounds with a view to increase the phase stability of sulfates. Herein, we report on various synthesis methods, such as solid-state, mechanochemical, and ionothermal treatments, to obtain nonreported until now compositions in the mixed phosphate-sulfate iron sodium alluaudite system, using the cost-effective precursors, Na3PO4 and FeSO4. Quite surprisingly, solid-state synthesis followed in situ using the synchrotron X-ray powder diffraction technique revealed the presence of an intermediate phase closely resembling the NaSICON phase Na2.65Fe2PO4(SO4)2 along with Na6Fe(SO4)4, prior to alluaudite formation. Physicochemical investigations of the alluaudite Na2.65Fe1.9(PO4) y (SO4)3-y phase, obtained via solid-state synthesis at 450 degrees C, confirm that the phosphate incorporation enhanced the thermal stability while preserving promising electrochemical properties, i.e., rate capability and long-term stability with no capacity loss after 50 cycles: a reversible capacity of approximate to 90 mAh/g is obtained at an average discharge voltage of 3.32 V vs Na+/Na and for an electrode mass loading of 16 mg/cm2. This study proposes easy and effective synthesis approaches to obtain series of compounds and opens the perspective to explore conditions of transitions between NaSICON and alluaudite structural types.

Halide-enriched lithium argyrodite superionic conductors are considered as promising candidates for all-solidstate batteries due to their soft structure and high ionic conductivity. Challenges remain, including chemical instability and incompatibility with anode materials, and in addition a deeper understanding of the fundamental aspects of ionic transport and performance is required. In this study, we investigated two argyrodite mixed-halide series of compositions, Li6_xPS5_xBrClx and Li5.5PS4.5Br1.5_ xClx. By employing a range of techniques including Xray diffraction (XRD), neutron diffraction, nuclear magnetic resonance (NMR) spectroscopy, electrochemical impedance spectroscopy and machine learning based molecular dynamics, we found that increasing the halide substitution enhances ionic conductivity. Notably, the Li5.4PS4.4BrCl0.6 composition achieves an ionic conductivity of 10 mS/cm, demonstrates superior air stability compared to conventional lithium argyrodites and allows for the fabrication of well-performing all solid-state batteries. Our results reveal that in lithium-poor compositions the lithium environments in the 4a and 4d cages become more alike, facilitating fast long-range lithium-ion transport. This work paves the way for the development of air-stable, high-conductivity sulfide electrolytes, advancing the practical implementation of solid-state batteries.