Jon Serrano-Sevillano

The first experimental realization of LiSbCl ₆ reveals a previously missing framework motif within lithium halide solid electrolytes. The structure-ion transport relationship established here reveals new design principles of solid electrolytes.

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.

P2-type layered sodium transition-metal oxides are promising high-energy cathodes for sodium-ion batteries but suffer from structural degradation and irreversible redox reaction 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 Na_2/3Mn_2/3Ni_1/3-yCu_yO₂ (y = 0, 1/6, 1/3) cathodes for sodium-ion batteries. Cu substitution not only raises average voltage 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 Na_2/3Mn_2/3Ni 1/6Cu1/6O2 to deliver 94.8 mAh g^-1 at an average voltage of 3.45 V (327 Wh kg^-1 ) with a 97% 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 Na_2/3Mn_2/3Ni_1/3O₂ develops a P2 to O2 transition together with a loss of crystallinity in the form of stacking faults, the partial Cu-substituted sample forms a more reversible OP4 structure above 4.0 V with less pronounced interlayerspacing changes. Operando X-ray absorption reveals sequential Ni²⁺ and Cu²⁺ oxidation to Ni³⁺ and Cu³⁺, respectively. Extend X-ray absorption fine structure (EXAFS) analysis, corroborated by density functional theory calculations (DFT), 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 Na_2/3Mn_2/3Ni_1/3O 2 and Na_2/3Mn_2/3Cu_1/3O₂ . Full-cell tests vs. hard carbon demonstrate the practical relevance, with Na_2/3Mn_2/3Ni_1/6Cu_1/6O₂ 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.

Direct recycling of silicon–carbon composite from a P50B 21700 cell.

High‐voltage cathodes such as LiMn _1.5 Ni _0.5 O ₄ (LNMO) offer promising energy density but suffer from interfacial degradation accelerated at elevated voltages and temperatures. Here, we present a comprehensive comparative study of three Li ₃ PO ₄ coating methods (precipitation, sol–gel, and dry sol–gel routes) applied to commercial LNMO powders. Coating quality and intimacy are systematically assessed using a correlative, multitechnique approach including ⁷ Li and ³¹ P solid‐state NMR, X‐ray diffraction, and electrochemical testing. A key insight from this study is the use of ssNMR relaxation behavior as a sensitive probe of coating intimacy to the active phase. The methodology is validated on commercial LNMO and reproduced in a lab‐synthesized LNMO to demonstrate reproducibility across particle morphologies. Among all methods, the sol–gel route produced a uniform ∼20 nm coating with optimal surface contact, translating to improved rate capability and outstanding high‐temperature cycling stability (87% retention after 100 cycles at 50 °C compared to 29% for the non‐coated LNMO), while retaining rate capability. These findings establish a practical framework for designing robust interfacial coatings in high‐voltage lithium‐ion battery materials.

Li⁺ and Na⁺ local ion dynamics in nitridophosphates Na₃V(PO₃)₃N and Li₃V(PO₃)₃N are evaluated here by means of solid-state nuclear magnetic resonance (NMR) and density functional theory (DFT) methods. In particular, the presence of diffusion pathways for the alkali metals within the crystal structures is evaluated experimentally by solid-state NMR and compared with bond valence energy landscape (BVEL) calculations. While no exchange between Na⁺ ions in Na₃V(PO₃)₃N was detected in the millisecond time scale, Li₃V(PO₃)₃N shows fast exchange between all Li⁺ positions in the structure. 2D ⁷Li-⁷Li EXSY solid-state NMR experiments performed at different mixing times were implemented to determine the Li-exchange rates. The observed diffusion mechanism involves the interconnection of all three alkali positions in the structure in a Li1 ↔ Li3 ↔ Li2 pattern. Nevertheless, the spontaneous Li exchange at room temperature between positions Li1 ↔ Li3 (k₁₃ = 826 Hz) is considerably faster than that between positions Li3 ↔ Li2 (k₂₃ = 207 Hz). These results are in agreement with the activation energies obtained for Li₃V(PO₃)₃N by the BVEL calculations performed in this work. These findings correlate well with the observed differences in the electrochemical performance of nitridophosphates A₃V(PO₃)₃N (A = Li, Na) and might be used to design future strategies for next-generation cathode materials.

FullProfAPP is a software tool for data processing, refinement and visualization of large collections of powder diffraction patterns. Featuring an intuitive graphical user interface, it seamlessly facilitates a variety of tasks. These include conducting full-profile phase searches, sequential and high-throughput Rietveld refinements, and managing background (and peak) detection. FullProfAPP also provides convenient interaction with crystallographic databases and supports the visualization and export of high-quality pixel and vector graphics depicting the refinement results, among other functionalities. FullProfAPP wraps around the refinement program FullProf [Rodríguez-Carvajal (1993), Physica B, 192, 55–69] and offers the flexibility of user-defined workflows by accessing and editing FullProf's input files and triggering its execution as necessary. FullProfAPP is distributed as open-source software and is presently available for Windows and Linux operating systems.

Among candidates at the positive electrode of the next generation of Li-ion technology and even beyond post Li-ion technology as all-solid-state batteries, spinel LiNi_0.5Mn_1.5O₄ (LNMO) is one of the favorites. Nevertheless, before its integration into commercial systems, challenges still remain to be tackled, especially the stabilization of interfaces with the electrolyte (liquid or solid) at high voltage. In this work, a simple, fast, and cheap process is used to prepare a homogeneous coating of Al₂O₃ type to modify the surface of the spinel LNMO: the supercritical fluid chemical deposition (SFCD) route. This process is, to the best of our knowledge, used for the first time in the battery field. Significantly improved performance was demonstrated vs those of bare LNMO, especially at high rates and for highly loaded electrodes.

Defects in crystalline structures play a vital role in their properties, so their proper characterization is essential to understanding and improving the behaviour of the materials. In this work, their presence in Ca₄Fe₉O₁₇ has been analysed. Its structure exhibits three different iron coordination topologies and can be described as layers of corner-sharing FeO₅ bipyramids stacked along the c axis together with layers of edge-sharing FeO₆ octahedra, both being linked by FeO₄ tetrahedra. The relative position of the FeO₄ tetrahedra generates three possible stacking directions, which results in stacking faults when more than one is combined. Structural refinement using the Rietveld method in X-ray and neutron powder diffraction data was not possible due to significant mismatches between the observed and calculated integrated intensities for several peaks resulting from this atomic disorder. Selected area electron diffraction (SAED) and high-resolution scanning transmission electron microscopy (HR-STEM) images confirm the local defective nature of the material. The FAULTS software enabled a successful refinement of the structure considering a high concentration of planar defects, conferred by the existence of three possible stacking directions in the crystal structure, all of them confined in the basal plane.