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High‐voltage spinel‐type structured LiNi0.5Mn1.5O4 (LNMO) shows promise as a next‐generation high‐energy‐density lithium‐ion battery cathode material, however, capacity decay on extended cycling hinders its widespread adoption, underscoring an urgent need for further development. In this work, we introduce Zn at octahedral 16c crystal sites in LNMO with Fd3‾ ${\bar{3}}$ m space group to improve rate capability and reduce the rapid capacity decay otherwise experienced during extended cycling. The current work resolves the detailed influence of isolated modification at octahedral 16c crystal sites, unveiling the mechanism for these performance improvements. We show that occupation of Zn at previously empty 16c sites prevents the migration of Ni/Mn to adjacent 16c sites, eliminating transformation to a rock‐salt type structured Ni0.25Mn0.75O2 phase above 4.8 V, preventing structure degradation and suppressing voltage polarization. This study provides insights into the fundamental structure‐function relationship of the LNMO battery cathode, pointing to pathways for the crystal structure engineering of materials with superior performance. [ABSTRACT FROM AUTHOR]

The use of Latin origin terms, relevant for sample characterization modalities, is described with a focus on samples under controlled conditions, samples within devices, and samples during physico-chemical evolution. The terms in vitro, in vivo, in situ, ab initio, in silico, post mortem, ex situ, posthumous, in vacuo, (in) operando, post facto, and ex post facto, as used in the scientific literature, are considered. Uses of the Latin origin terms in situ, extra situm, in operando, in vivo, in vacuo, in vitro, extra vivum, post facto and ex post facto, ab initiis, computatro, and post mortem are discussed. It is suggested that these terms are to be used without hyphenation and that all Latin derived terms are set in italic font. [ABSTRACT FROM AUTHOR]

Ion‐exchange materials are commonly composed of polyelectrolyte networks in which crosslinking preserves macroscopic geometry and prevents dissolution in aqueous conditions. However, crosslinking inherently inhibits efficient swelling and mass transfer during ion‐exchange processes. Herein, a one‐step polymerization‐induced microphase separation (PIMS) approach directly using water and linear polystyrene sulfonate macromolecular chain transfer agents (macroCTAs) is developed to engineer bicontinuous nanostructured materials with rapid ion‐exchange capabilities. These materials feature water‐swollen liquid‐like polyelectrolyte domain embedded in a rigid polymer network, where the domain spacing, as determined by small angle X‐ray scattering experiments, is precisely modulated between 15 and 89 nm based on the molecular weight of the macroCTA used. As the bicontinuous nanostructure enables rapid mass transfer throughout the material bulk, the 3D printed PIMS materials are able to rapidly remove model charged dyes from solution, exhibiting a mass transfer coefficient ≈35 times higher than commercially available counterparts. This work is the first example demonstrating direct self‐assembly of water into continuous nanochannels in a well‐controlled manner as supported by time‐resolved small‐angle neutron scattering experiments during polymerization. Moreover, these nanostructured materials are readily produced using commercially available 3D printers, enabling unparalleled high‐resolution fabrication of targeted complex structures, including accurately controllable macroporous geometries and surface areas. [ABSTRACT FROM AUTHOR]

Wadsley‐Roth niobium oxide phases have attracted extensive research interest recently as promising battery anodes. We have synthesized the niobium‐molybdenum oxide shear phase (Nb, Mo)13O33 with superior electrochemical Li‐ion storage performance, including an ultralong cycling lifespan of at least 15000 cycles. During electrochemical cycling, a reversible single‐phase solid‐solution reaction with lithiated intermediate solid solutions is demonstrated using in situ X‐ray diffraction, with the valence and short‐range structural changes of the electrode probed by in situ Nb and Mo K‐edge X‐ray absorption spectroscopy. This work reveals that the superior stability of niobium molybdenum oxides is underpinned by changes in octahedral distortion during electrochemical reactions, and we report an in‐depth understanding of how this stabilizes the oxide structure during cycling with implications for future long‐life battery material design. [ABSTRACT FROM AUTHOR]

Despite being the major cause of safety and performance issues in lithium metal batteries, experimental difficulties in quantifying directly the morphology of lithium deposited at electrode surfaces have meant that the mechanism of metallic lithium growth within batteries remains elusive. This study demonstrates that quantitative detail about the morphology of metallic lithium within batteries can be derived non‐destructively and directly using in situ ultra‐small and small‐angle neutron scattering. This information is obtained over a large electrode area in cells where lithium deposition processes are typical of real‐world applications. Complex variations of surface area and interfacial distances 1–10 µm and 100–300 nm are revealed in size that are influenced by current density and cell cycling history, providing valuable insight into the growth of metallic lithium features detrimental to battery performance. Such quantitative insight into the process of lithium growth is required for the development of safer high‐performance lithium metal batteries. [ABSTRACT FROM AUTHOR]

Electrochemical carbon dioxide (CO2) reduction (ECR) is a promising technology to produce valuable fuels and feedstocks from CO2. Despite large efforts to develop ECR catalysts, the investigation of the catalytic performance and electrochemical behavior of complex metal oxides, especially perovskite oxides, is rarely reported. Here, the inorganic perovskite oxide Ag‐doped (La0.8Sr0.2)0.95Ag0.05MnO3–δ (LSA0.05M) is reported as an efficient electrocatalyst for ECR to CO for the first time, which exhibits a Faradaic efficiency (FE) of 84.3%, a remarkable mass activity of 75 A g−1 (normalized to the mass of Ag), and stability of 130 h at a moderate overpotential of 0.79 V. The LSA0.05M catalyst experiences structure reconstruction during ECR, creating the in operando‐formed interface between the perovskite and the evolved Ag phase. The evolved Ag is uniformly distributed with a small particle size on the perovskite surface. Theoretical calculations indicate the reconstruction of LSA0.05M during ECR and reveal that the perovskite–Ag interface provides adsorption sites for CO2 and accelerates the desorption of the *CO intermediate to enhance ECR. This study presents a novel high‐performance perovskite catalyst for ECR and may inspire the future design of electrocatalysts via the in operando formation of metal–metal oxide interfaces. [ABSTRACT FROM AUTHOR]

Oxygen‐ion conducting perovskite oxides are important functional materials for solid oxide fuel cells and oxygen‐permeable membranes operating at high temperatures (>500 °C). Co‐doped perovskites have recently shown their potential to boost oxygen‐related kinetics, but challenges remain in understanding the underlying mechanisms. This study unveils the local cation arrangement as a new key factor controlling oxygen kinetics in perovskite oxides. By single‐ and co‐doping Nb5+ and Ta5+ into SrCoO3‐δ, dominant factors affecting oxygen kinetics, such as lattice geometry, cobalt states, and oxygen vacancies, which are confirmed by neutron and synchrotron X‐ray diffraction as well as high‐temperature X‐ray absorption spectroscopy, are controlled. The combined experimental and theoretical study unveils that co‐doping likely leads to higher cation dispersion at the B‐site compared to single‐doping. Consequently, a high‐entropy configuration enhances oxygen ion migration in the lattice, translating to improved oxygen reduction activity. [ABSTRACT FROM AUTHOR]

In operando powder diffraction remains one of the most powerful tools for non‐destructive investigation of battery electrode materials. While in operando X‐ray, especially synchrotron radiation, powder diffraction is by now a routine experimental technique, in operando neutron powder diffraction is still less established. We present a new electrochemical cell for in operando neutron powder diffraction, which is, first and foremost, easy to use, but can also cycle electrode materials under electrochemical conditions close to those achieved using standard laboratory cells. The cell has been designed in multiple sizes, and high‐quality electrochemical and neutron powder diffraction data is presented for sample sizes as low as 48 mg total active material. The cell handles lithium‐ion and sodium‐ion materials equally well, with no difference in how the cell is prepared and assembled. The cell is intended to be used as sample environment at powder diffractometers at the neutron facilities MLZ, ORNL and ACNS. [ABSTRACT FROM AUTHOR]

Oxides composed of an oxygen framework and interstitial cations are promising cathode materials for lithium‐ion batteries. However, the instability of the oxygen framework under harsh operating conditions results in fast battery capacity decay, due to the weak orbital interactions between cations and oxygen (mainly 3d–2p interaction). Here, a robust and endurable oxygen framework is created by introducing strong 4s–2p orbital hybridization into the structure using LiNi0.5Mn1.5O4 oxide as an example. The modified oxide delivers extraordinarily stable battery performance, achieving 71.4 % capacity retention after 2000 cycles at 1 C. This work shows that an orbital‐level understanding can be leveraged to engineer high structural stability of the anion oxygen framework of oxides. Moreover, the similarity of the oxygen lattice between oxide electrodes makes this approach extendable to other electrodes, with orbital‐focused engineering a new avenue for the fundamental modification of battery materials. [ABSTRACT FROM AUTHOR]

While some works in this Special Collection highlight recent developments in the in situ and (in) operando characterisation techniques that have been successfully applied for more than a decade, such as X-ray and neutron diffraction and X-ray spectroscopy ( B Liang et al b ., B Wu et al b ., B Gustafsson et al b ., B Chien et al b ., B Lebens-Higgins b ), some new rising methods such as acoustic emission methods ( B Schweidler et al b .), This B Special Collection b concerns the recent evolution of methods and techniques used to understand the function of such materials, a necessary step towards the rational design of new energy storage technology with improved performance characteristics. Such characterisation methods would ideally give information about energy storage materials and components that are performing as they would in the operating device, as close to real-world applied conditions and with as much detail as possible. [Extracted from the article]

The article focuses on the synthesis and characterization of a high-entropy oxide (HEO) called Iron(II) Oxide (FeO)-HEO, which contains divalent Manganese (Mn) and Iron (Fe) in a rocksalt crystal structure. Topics include the concept of HEOs and their unique compositional features, the challenge of introducing divalent Mn(II) and Fe(II) into a rocksalt HEO, and the phase stability of FeO-HEO under different conditions.

In situ neutron powder diffraction experiments are applied to physical, kinetic, and microstructural characterization of uranium mononitride as a promising light water reactor fuel material. The temperature-variable coefficient of thermal expansion and isotropic Debye Waller factors are obtained by sequential Rietveld refinement over 499–1873 K. Oxidation of a UN pellet (95.2% density) under flow of 11 mg/min D 2 O is observed to initiate above 623 K and the rate increases by a factor of approximately 10 from 673 to 773 K, with activation energy 50.6 ± 1.3 kJ/mol; uranium oxide is the only solid corrosion product. [ABSTRACT FROM AUTHOR]