Epitaxial LiNi1/3Mn1/3Co1/3O2 (NMC) thin films are prepared via pulsed laser deposition to model fundamental electrochemical behavior and lithium-ion transport kinetics based on different crystallographic orientations and defect types. The observed growth direction and surface termination of NMC thin films are linked to surface energy minimization, primarily via the (104) and (003) planes. The shortest diffusion path for lithium-ion transport is achieved for a film thickness of ≈15 nm via optimal (100)-oriented growth of NMC, indicating selective growth direction of NMC domains. Analysis of interfaces and local crystal structure revealed two predominant types of defects: antiphase boundaries (APBs) and twinned domains, which are strictly related to the symmetry of the layered structure and columnar epitaxial growth of NMC domains. Electrochemical testing vs Li/Li+ at charge/discharge rates from C/10 up to 6 C showed that performance is influenced by both the crystallographic orientation of lithium transport pathways and the presence of structural defects. Specifically, (104)- and (1̅08)-oriented NMC thin films with twinned microstructure exhibited stable cycling, delivering specific discharge capacities of 66.2 μA cm-2 μm-1 (141.2 mAh g-1) and 70.2 μA cm-2 μm-1 (149.4 mAh g-1) at C/10, along with apparent lithium diffusion coefficients of 7.45 × 10-15 cm2 s-1 and 7.95 × 10-15 cm2 s-1, respectively. In contrast, (003)- and (1 0 16)-oriented thin films exhibited lower apparent lithium diffusion coefficients and limited functionality due to less favorable orientations of lithium slabs, higher density of APBs, and unit cell distortion. These factors contribute to a noticeable decline in average discharge voltage at higher discharge rates across all orientations except (104). This approach reveals an intrinsic correlation between the structural properties and electrochemical response of epitaxial NMC thin films and serves as a future guideline toward high-performance NMC cathodes.

We present a study of structure, microstructure, nanostructure and magnetic state of the CexPrNdSm (x = 0.01-1.5) medium-entropy alloys composed of the light rare earths only. Magnetic light rare earths are fundamentally different from the heavy ones, because the crystal-field interaction in the former is able to reduce or completely destroy the ionic magnetic moments at low temperatures. The alloys crystallize in a double hexagonal close-packed structure in the form of a single-phase nanostructured solid solution. The low-temperature magnetic state is inhomogeneous, being a mixture of paramagnetic domains appearing in the crystal regions with larger destruction of the moments and spin glass (SG)-type spin domains in the regions with less destructed moments. Such mixed state is intrinsic and specific to the light-lanthanide multi-component solid solutions. The SG-type domains are magnetically frustrated spin entities with broken ergodicity below the spin freezing temperature Tf. In the low-Ce content alloys, the SG-type domains resemble canonical SGs, while in the Ce-concentrated alloys, some ferrimagnetically ordered clusters with nonzero spontaneous magnetization have formed additionally. The increased Ce content x continuously reduces the average exchange coupling, as evidenced from the shift of Tf towards lower temperatures and the speed-up of spin dynamics into the direction of superparamagnets.

The development of material acceleration platforms in battery research requires integrating complementary techniques and correlating heterogeneous experimental datasets. Here, this challenge is tackled in a large-scale multimodal program involving fifteen laboratories and facilities across Europe. Coordinated multi-site experiments are performed on state-of-the-art graphite / LiNiO2 Li-ion full cells to address two archetypal scientific questions: is the electrolyte composition impacting electrode properties, and how do electrode materials evolve when cells are cycled to their end-of-life? A fully standardized and centralized workflow is demonstrated, from sample production and delivery, to metadata and data handling, generating seventy-five concatenated datasets shared among all partners. Their integrated analysis shows that scientific conclusions depend critically on both the observable chosen to describe electrode properties, and the measurement technique employed. Individual experiments provide detailed information into specific aspects, such as crystal structures, redox activity, surface processes, morphology, etc., but can also function as binary diagnostic tool. Two-dimensional observable-technique patterns are introduced, in which each pixel encodes a yes, no or uncertain answer to a given scientific question. These patterns serve as multi-property metaviews, e.g. visual genotypes, enabling to classify material behavior and technique suitability according to predefined user demand and criteria, highlighting the interdependencies between measurement choices, extracted parameters and scientific interpretation. This multimodal workflow establishes a proof-of-concept for correlative analysis and underscores challenges toward fully integrated, automated and holistic approaches in energy material science.

Rechargeable magnesium batteries (RMBs) are gaining significant attention as next-generation energy storage due to high theoretical volumetric energy density, abundance, and low cost of Mg metal. However, practical development remains constrained by surface passivation, cycling instability, and scarcity of compatible electrolytes. In this study, we explore the incorporation of fluorinated cyclic ethers in Mg[Al(hfip)(4)](2)/diglyme-based electrolytes. The addition of 10 vol.% fluorinated cyclic ether improves the electrochemical performance of Mg metal, evidenced by improved coulombic efficiency (98.2% to 99.1%), cycling life (15 vs 90 cycles of Mg plating/stripping at 2 mA cm(-2) and 2 mAh cm(-2)), and oxidative stability (3.7 V to 4.1 V vs Mg-0/Mg2+). The optimized electrolyte also enables stable and prolonged cycling in high-voltage Mg||polyaniline cells, achieving 75% capacity retention over 500 cycles at 1C. Operando electrochemical impedance spectroscopy, supplemented by scanning electron microscopy and X-ray photoelectron spectroscopy, was employed to explain the improvement. The electrochemical bottleneck processes occurring on the Mg metal anode without fluorinated ether addition were determined to be incomplete electrode activation, high surface area deposits formed during plating, and passivation of such deposits. These findings highlight the potential of fluorinated ether additives in improving Mg metal performance and advancing electrolyte design for next-generation RMBs.

A realistic evaluation of electrocatalyst stability requires experimental setups that accurately reproduce the coupled chemical and transport environments of membrane-electrode assemblies. Conventional GDE half-cells, however, are typically operated without a proton-exchange membrane, exposing the catalyst layer directly to liquid electrolytes and intensifying dissolution-migration-redeposition dynamics. Here, we examine how the presence of a membrane alters degradation in PtCo/C catalyst layers and establish a quantitative workflow for tracking nanoparticle evolution under realistic conditions. Particle-size distributions (PSDs) are extracted directly from low-kV identical-location SEM (IL-SEM) images of intact, micrometer-thick porous catalyst layers and validated against IL-TEM for surface-accessible particles. Automated segmentation enables robust, high-throughput analysis across large datasets. Applying this framework to accelerated stress tests reveals that membrane-free GDEs undergo pronounced coarsening driven by severe Pt dissolution and redeposition under direct acid exposure, whereas membrane-protected electrodes constrain transport pathways and therefore exhibit more moderate, representative degradation behaviour. These findings underscore the indispensable role of the membrane for realistic half-cell durability studies and demonstrate that automated IL-SEM-based PSD analysis provides a powerful framework for linking morphological evolution to electrochemical performance in complex, three-dimensional porous electrocatalyst systems.

Understanding Pt/C catalyst degradation under relevant proton‐exchange membrane fuel cell (PEMFC) conditions remains challenging because most identical‐location studies are conducted under nonrepresentative conditions (rotating disk electrode), configurations at low current densities. In this work, we combine a gas diffusion electrode platform with identical‐location scanning electron microscopy (IL‐SEM) to track morphological changes in Pt/C catalysts during accelerated stress testing while evaluating oxygen reduction reaction (ORR) performance at fuel‐cell‐relevant current densities (up to ∼1 A cm−2). Reliable relocation of identical sites is achieved using unique crack patterns in the gas diffusion electrode (GDE) catalyst layer as intrinsic markers. IL‐SEM imaging before and after electrochemical treatment reveals Pt nanoparticle restructuring after 10,000 accelerated stress test (AST) cycles, whereas no detectable morphological changes are observed after the initial break‐in procedure. Higher resolution IL‐SEM shows environment‐dependent degradation pathways, with isolated particles predominantly undergoing dissolution/redeposition and particle‐rich regions more frequently exhibiting detachment/agglomeration. Within the resolution and depth sensitivity of SEM, no clear morphological changes are detected in the carbon support. Complementary transmission electron microscopy (TEM) particle‐size analysis shows depletion of the smallest Pt particles after AST, consistent with their dissolution and subsequent redeposition onto larger particles. These results demonstrate that the combined IL‐SEM/GDE approach provides a route for directly identifying nanoscale degradation mechanisms under electrochemical conditions substantially closer to real fuel‐cell operation.

Ni-rich layered oxides are promising cathode materials for lithium-based batteries due to their high energy density. However, their long-term performance is limited by interfacial and structural instabilities during cycling. To address this, we developed an intertwined hybrid network that forms a robust artificial cathode-electrolyte interphase (CEI) via a simple one-step wet impregnation process without thermal treatment. The hybrid network combines a lithium single ion conducting polymer (SICP) for ionic transport, multi-walled carbon nanotubes (MWCNTs) for electronic conductivity, and polyvinylpyrrolidone (PVP) to ensure uniform dispersion. This synergistic architecture enhances coupled ionic-electronic transport and improves interfacial kinetics, leading to greater electrochemical stability. As a result, coated Ni-rich cathodes show significantly improved cycling performance in both liquid and solid-state systems under pressure-free conditions. In liquid electrolytes, the coated material retains 64% capacity after 200 cycles, compared to 41% after 100 cycles for the pristine material. In solid-state cells, it retains 55% capacity after 45 cycles, outperforming the pristine material (59% after 20 cycles). This scalable approach provides an effective strategy for stabilizing high-energy cathodes and is applicable to various battery architectures.

State-of-the-art battery cells are composed of complex heterogeneous electrode structures that pose significant challenges for analyzing electrochemical processes. Traditional electrochemical impedance spectroscopy (EIS) techniques require system simplification and equilibrium conditions, which limit their ability to capture dynamic processes during battery operation. This paper introduces an advanced method, which combines operando impedance measurements with real-time monitoring of overvoltage in a three-electrode cell setup. This approach enables detailed analysis of processes occurring under actual operating conditions, overcoming limitations of conventional EIS. The benefits of operando EIS are demonstrated through the study of lithium-metal electrodes during repetitive stripping and plating cycles. The technique allows for the identification and quantification of various electrochemical processes, including those related to lithium diffusion, surface morphology changes, and dendritic growth. The findings highlight the importance of operando impedance spectroscopy in providing insights that are not accessible through traditional EIS methods, particularly in understanding complex phenomena such as internal short circuits and lithium pitting. The study emphasizes the necessity of combining operando impedance measurements with equilibrium measurements to achieve a comprehensive understanding of battery behavior during operation.

This study examines the structural and electrochemical behavior of epitaxial (104) oriented LiNi1/3Mn1/3Co1/3O2 (NMC 111) thin film cathodes prepared by pulsed laser deposition, aiming to elucidate the underlying mechanisms of reversible lithium-ion cycling. The effect of growth parameters on film morphology and crystal structure is thoroughly studied. The surface analysis confirms the oxidation states of transition metal ions to be Ni2+, Mn4+ and Co3+. Microstructural analysis reveals twinned domains in the NMC 111 layered structure, which conforms with its 4-domain crystallographic orientation. After NMC 111 thin film is charged to 4.2 V, a change in the local electronic structure of nickel and oxygen ions is observed by electron energy loss spectroscopy as a consequence of nickel oxidation. By utilizing ex situ reciprocal space mapping after charging to 4.2 V, a negative unit cell volume change was observed, compensated by an increased mosaic spread of NMC 111 lattice planes. This structural adjustment is reversibly maintained upon discharging to 3.0 V. Based on defined epitaxial structures, the reversible mechanism of lithiation and delithiation in NMC 111 thin films is determined on a structural level, providing detailed insight into its functionality. To address structural instability in the charged state, the electrochemical performance was enhanced by cooling the NMC 111 thin films under high oxygen pressure.

LiNiO2 (LNO), one of the most promising Ni-rich cathode materials for Li-ion batteries is limited in its practical applicability due to structural and surface degradation. Protective surface coatings are a viable strategy to create a stable interface. In this work, the surface modification of LNO cathode using mixed electron/ion conductive composite coatings based on carboxyl-functionalized multi-walled carbon nanotubes (oMWCNTs) and polyacrylic acid (PAA) is presented, aiming at an optimal balance of electronic and ionic conductivity, respectively. In-situ conversion reaction of PAA with the detrimental Li residues (Li2CO3, LiOH) on LNO surface into lithium polyacrylate (LiPAA) coating layer is demonstrated to facilitate Li+ ion transport. Fine-tuning of the oMWCNT/PAA ratio shows that the electrochemical performance of the LNO cathode is improved when the ionic contribution is increased to 75% of the total coating. Galvanostatic cycling of coated LNO@oMWCNT/PAA (1:3) in a half-cell configuration shows a capacity retention of 92.5% at the end of 100 cycles at 0.2C, while the uncoated cathode retains only 76.7%. In non-optimized LNO//graphite full cells, the capacity retention improves from 68.4 % for the uncoated LNO to 87.5 % for the coated sample. Finally, operando gas evolution analysis of the LNO electrode by OEMS (online electrochemical mass spectrometry) studies shows that the coated electrode produces significantly less amount of gases during the electrochemical cycling, including hindering of oxygen evolution at high voltage compared to the uncoated LNO electrode, proving the positive effect of the oMWCNT/PAA coating.

Understanding material transformations at the nano- and microscale is essential for advancing electrocatalysis, energy storage, and other applications. Conventional SEM imaging, which captures random locations before and after treatment, struggles to distinguish real transformations from inherent sample heterogeneity. Identical Location SEM (IL-SEM) overcomes this by enabling re-imaging of the exact same region, offering clear evidence of localized changes in morphology, structure, and composition. Despite its simplicity and wide applicability, IL-SEM remains underutilized. This article presents a detailed, practical guide to implementing IL-SEM reliably, including sample alignment, multiscale imaging, and consistent re-localization. Key methodological tips and solutions to common challenges are provided, making the approach accessible even for non-expert users. To showcase its versatility, we present case studies involving electrocatalysts, alloys, and nanostructured materials. Moreover, by integrating IL-SEM with energy-dispersive spectroscopy (EDS) and electron backscatter diffraction (EBSD), we demonstrate how compositional and crystallographic evolution can be tracked alongside morphological changes. This optimized workflow offers a powerful, non-destructive method for visualizing dynamic material behavior and provides a foundation for IL-SEM to become a standard technique for studying structural evolution across diverse materials research fields.

Hard carbons are promising negative electrode materials for Na-ion batteries (SIBs), and the process of (de)insertion of Na+ ions into/from hard carbons has attracted much attention in recent research. Being a relatively new technology compared to lithium-ion batteries, the precise operational mechanism and degradation pathways of SIBs remain elusive. In this investigation, we focus on elucidating the physical and electrochemical attributes of corncob-derived hard carbon synthesized at 1400 degrees C using operando, in situ and ex situ solid-state NMR spectroscopy techniques, complemented by other advanced characterization methods, such as SEM-EDX, XPS and electrochemistry. Through the analysis of 23Na NMR spectra of hard carbon, we gained insights into sodium insertion within the active material, which is characterized by the shifting NMR peak during the (de)sodiation process. Furthermore, our findings revealed the formation of a solid electrolyte interphase (SEI) at the hard carbon electrode and pore surface, predominantly in the form of Na2CO3 in the bulk of the SEI, and NaF at the SEI surface, alongside the occurrence and differentiation of plating and metal sodium dendrites.

The interface between the semiconductor light absorber and the metal electrode is critical for facilitating the extraction of photogenerated charges in photoelectrodes. Achieving a lattice-matched semiconductor/electrode interface with low defect density is highly desirable but remains a challenge for Ta3N5 photoanodes. In this study, we synthesized niobium nitride thin film electrodes with controllable crystallographic phases to achieve a lattice-matched Ta3N5/Nb5N6 back contact. This results in an enhanced crystallinity of the Ta3N5 film and reduced interfacial defect density. Consequently, the photoanode with the lattice-matched back contact attains a record half-cell solar-to-hydrogen conversion efficiency of 4.1%, attributed to the bulk carrier separation efficiency of nearly 100%. This work highlights lattice-matching as an effective strategy to enhance the efficiency of thin film-based solar energy conversion devices.

The push to use metallic lithium-based batteries motivates a shift toward the use of solid polymer electrolytes. To improve the ionic conductivity values of such electrolytes, liquid additives (plasticizers) are usually added. However, the improvement in conductivity comes at the expense of a deterioration of the anode-electrolyte interface, resulting in poorer electrochemical cell performance. In this study, the use of a polymer coating consisting of polyethylene oxide, LiTFSI, and LiNO3 is proposed. The coating shows improved electrochemical performance and stability, delayed cell failure and a more uniform distribution of Li deposits. These improvements are attributed to the increased stability of the solid electrolyte interphase, which is confirmed by using a combination of electrochemical impedance spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. In contrast, it is found that the interphase in uncoated Li electrodes is likely affected by continuous reactions with the plasticizer, further confirming the need to use such protective coatings to achieve long-term operation in practical solid-state Li metal batteries.

Teeth exemplify architectures comprising an interplay of inorganic and organic constituents, resulting in sophisticated natural composites. Rodents (Rodentia) showcase extraordinary adaptations, with their continuously growing incisors surpassing human teeth in functional and structural optimizations. In this study, employing state-of-the-art direct atomic-scale imaging and nanoscale spectroscopies, we present compelling evidence that the release of material from ameloblasts and the subsequent formation of iron-rich enamel and surface layers in the constantly growing incisors of rodents are complex orchestrated processes, intricately regulated and independent of environmental factors. The synergistic fusion of three-dimensional tomography and imaging techniques of etched rodent́s enamel unveils a direct correlation between the presence of pockets infused with ferrihydrite-like material and the acid resistant properties exhibited by the iron-rich enamel, fortifying it as an efficient protective shield. Moreover, observations using optical microscopy shed light on the role of iron-rich enamel as a microstructural element that acts as a path for color transmission, although the native color remains indistinguishable from that of regular enamel, challenging the prevailing paradigms. The redefinition of "pigmented enamel" to encompass ferrihydrite-like infusion in rodent incisors reshapes our perception of incisor microstructure and color generation. The functional significance of acid-resistant iron-rich enamel and the understanding of the underlying coloration mechanism in rodent incisors have far-reaching implications for human health, development of potentially groundbreaking dental materials, and restorative dentistry. These findings enable the creation of an entirely different class of dental biomaterials with enhanced properties, inspired by the ingenious designs found in nature.

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This work focuses in-depth on the quantitative relationships between primary first-order microstructural parameters (i.e., volume fractions of various phases and particle size distribution) with the more complex second-order topological features (i.e., connectivity of phases, three-phase boundary length (TPBL), interfacial areas, or tortuosity). As a suitable model material, a cermet nickel/samaria-doped ceria (Ni-SDC) is used as an anode in a solid oxide fuel cell (SOFC). A microstructure description of nano-sized Ni-SDC cermets, fabricated at various sintering conditions from 1100 °C to 1400 °C, was performed using FIB-SEM nanotomography. The samples were serially sectioned employing a fully automated slicing procedure with active drift correction algorithms and an auto-focusing routine to obtain a series of low-loss BSE images. Advanced image processing algorithms were developed and applied directly to image data volume. The microstructural–topological relationships are crucial for the microstructure optimisation and, thus, the improvement of the corresponding electrode performance. Since all grains of individual phases (Ni, SDC, or pores) did not percolate, special attention was given to the visualisation of the so-called active TPBL. Based on the determined microstructure characteristics of the prepared Ni-SDC cermets, including simulations of gas flow and pressure drop, thermal treatment at 1200 °C was recognised as the most appropriate sintering temperature.