Sodium-ion batteries (SIBs) with O3-type cathodes are among the most promising alternatives to lithium-ion batteries. However, their application is limited by the severe irreversible anionic redox reactions and phase transitions under high-voltage conditions. In this study, we found that these irreversible processes could be effectively alleviated by precise alkali-metal layer spacing modulation via tuning initial sodium content, which significantly enhances the high-voltage performance of O3-type layered materials. Our results reveal that irreversible anionic redox reactions are triggered prematurely in cathodes with a high initial sodium content. It is noteworthy that these irreversible processes always lead to detrimental phase transitions, incomplete transition-metal redox, and exacerbated cation migration in layered cathodes. Through precise regulation of the initial Na content from unity to 0.8, the aforementioned issues were effectively alleviated, enabling a high initial discharge capacity of 174 mAh g-1 at 0.2 C, with 161 mAh g-1 retention after 100 cycles. Moreover, the optimized sample delivered outstanding full-cell performance with a specific capacity of 154 mAh g-1 at 1 C and a capacity retention of 81.8% after 200 cycles. These findings highlight the critical role of sodium stoichiometry in regulating anionic redox and stabilizing layered structures, offering insights into the high-performance SIB cathode design.

Chalcopyrite (CuFeS2), composed of earth-abundant and environmentally benign elements, was synthesized via solid-state sintering of an equimolar CuS/FeS mixture and evaluated as a cathode material for lithium all-solid-state batteries (ASSBs). CuFeS2 was compared with a mixture of the CuS and FeS parent materials, which are theoretically expected to show similar conversion reaction products during lithiation. Galvanostatic cycling, XRD, XAS, SEM, and EDX analyses revealed that both samples undergo displacement reactions with lithium, leading to phase separation into Cu0, Fe0, and Li2S. However, CuFeS2 exhibits superior reversibility due to the formation of intermediate phases (LiCuFeS2, Li3CuS2, Li2FeS2), where Cu-related phases may promote uniform Fe reactivation during charging. The synergistic Cu-Fe interactions improve reaction kinetics and reversibility, thereby enhancing overall electrochemical performance. In contrast, the CuS-FeS composite exhibits rapid capacity decay due to independent phase segregation and irreversible Fe0 passivation. Electrochemically, CuFeS2 delivers 207 mAh g-1 with 61% retention after 100 cycles, outperforming CuS-FeS (132 mAh g-1, 40% retention). This work provides the most detailed mechanistic insight to date into the function of CuFeS2 in rechargeable Li cells and shows that controlled intermediate distribution and dynamically evolved conductive networks during phase transformation can improve conversion-type electrodes for ASSBs.

The development of high-performance lithium-carbon dioxide (Li-CO2) batteries is crucial for advancing carbon-neutral energy storage systems. However, this system still faces the challenge of balancing high discharge voltage with long-term stability. To address this issue, we have successfully designed and synthesized a novel nanocrystalline PtIrFeCoCuZn (PIFCCZ) high-entropy intermetallic cathode catalyst with an L12-type atomic ordered structure. The surface superlattice of PIFCCZ induces a molecular-level spatial confinement effect, which effectively disrupts the conventional crystallization pathway of discharge products, enabling the separated nucleation and growth of finely crystalline Li2CO3 and amorphous Li2C2O4. The precisely controlled interfacial coupling between discharge products and catalyst surface significantly enhances the reversible decomposition of discharge products and reduces the CO2 evolution overpotential to 0.24 V. The Li-CO2 battery incorporating this catalyst achieved a high discharge voltage of 3.08 V, an energy efficiency of 93.7%, and stable operation for over 1000 h at a current density of 20 μA·cm-2. This study provides a breakthrough strategy for resolving the inherent trade-offs among output voltage, energy efficiency, and cycling stability in Li-CO2 batteries.

Sodium-ion batteries represent a promising technology for large-scale cost-effective energy storage. However, the deployment of O3-type layered cathodes for high-voltage operation is critically impeded by coupled chemo-mechanical failure, manifesting as intergranular microcracking and irreversible lattice oxygen release. Here, we construct a coherent, epitaxial interface that mechanically arrests crack propagation and chemically locks surface oxygen against high-voltage anionic redox. Guided by the Goldschmidt tolerance factor, we exploit the ionic radius mismatch of heavy late lanthanides to drive the formation of a dense, cation-disordered rock-salt shell. Advanced diagnostics, including O K-edge mRIXS and 3D electron diffraction, provide unambiguous evidence that this architecture effectively suppresses gas evolution and crack propagation. Consequently, the stabilized architecture limits voltage decay to 0.74 mV per cycle and retains 84.3% of the initial capacity after 200 cycles at 1C, nearly doubling the retention of the pristine counterpart (45.0%). This reconstruction strategy mitigates the chemo-mechanical degradation of O3-type cathodes, offering a practical pathway toward stable, long-life sodium-ion batteries.

Sodium-ion batteries (SIBs) are considered promising candidates for energy storage devices due to their abundant resources and low cost. In this study, Cr-based metal-organic frameworks (MOFs) are chosen to modify the NaCrO2 cathode material during the synthesis process for achieving prominent electrochemical performances. The modified NaCrO2 demonstrates significantly superior rate performance compared to pristine NaCrO2; for instance, while pristine NaCrO2 struggles to charge and discharge at 50C, the coated material retains a capacity of 72.9 mA h g-1 even at this high rate. Even at an elevated temperature of 55 degrees C, the coated NaCrO2 exhibits excellent cycling stability, retaining 85% of its initial capacity after 200 cycles at 0.5C, demonstrating its robust performance under challenging conditions. Comprehensive characterization, including Neutron Powder Diffraction (NPD), X-ray Absorption Spectroscopy (XAS), and in situ X-ray Diffraction (XRD), reveals that the Cr2O3-C coating on the surface of the NaCrO2 cathode significantly enhances surface ionic transport while minimizing side reactions with the electrolyte by effectively isolating direct contact between the electrode and the electrolyte. The MOF-modified strategy improves cycling stability by suppressing interfacial side reactions and optimizing the phase transition process, while enhancing rate capability by facilitating ion transport. This work provides new insights for the design of high-rate, wide-temperature, and low-cost large-scale energy storage systems.

The potential profile of layered oxides as cathodes for Na-ion batteries can be well tuned by cation doping. Doping typically leads to changes in the phase behavior and the redox chemistry, but the processes and design rules are often unclear, especially at potentials above approximately 4 V vs. Na+/Na. Here, we study by means of synchrotron methods and DFT calculations how Mg- and Sc-doping influences the properties of layered O3-NaNi0.5Mn0.5O2. A strong oxygen redox activity is observed at high voltages and both dopants are found to be effective for decreasing the number of phase transitions and for improving cycle life. When comparing the effect of the dopants, notable differences in the first cycle are observed. While the Sc doping maintains the high voltage plateau, Mg doping causes a more sloping behavior. This difference can be understood from the appearance of a new redox center (arising from the ‘O bound to Mg') having a higher redox potential but being more irreversible compared to the redox activity of ‘O bound to Ni'. The appearance of an additional redox center explains findings obtained for other doped Ni- and Mn-based layered oxides, which also show a sloping potential in the high voltage region.

Catalytic CO2 reduction into value-added products is an energy-intensive process and typically relies on molecular hydrogen as reductant. Coupling CO2 reduction with propane dehydrogenation for in situ hydrogen generation presents a sustainable alternative but conventionally demands high temperatures, causing undesirable side reactions such as cracking and coke formation. Here, we demonstrate a nonthermal catalytic pathway driven by hot electrons generated via localized surface plasmon resonance. Using a plasmonic catalyst comprising Ga-Ni-Mn active sites anchored on broadband plasmonic "black gold," we achieve tandem CO2 reduction and propane dehydrogenation under visible-light irradiation. The catalyst consistently produces equimolar amounts (~1,600 µmol g-1 h-1) of CO and propene under flow conditions, maintaining exceptional stability even after 500 h. Notably, light illumination suppresses undesired side reactions, such as dry reforming of propane, cracking, and coking, preserving a stable stoichiometric ratio of CO and propene. Mechanistic studies, including controlled thermal experiments, Arrhenius analysis, and finite-difference time-domain simulations, confirm that catalytic selectivity and stability originate specifically from plasmon-induced hot electrons rather than photothermal effects. Comprehensive structural characterization using X-ray absorption near-edge structure and extended X-ray absorption fine structure, in situ diffuse reflectance infrared Fourier transform spectroscopy, ultrafast transient absorption spectroscopy, and density functional theory calculations elucidate that plasmonic excitation promotes advantageous charge-transfer states within Ga-Ni-Mn ensembles, facilitating selective activation of CO2 and propane. This study establishes hot electron-driven plasmonic catalysis as a distinctive strategy for tandem propane dehydrogenation and circular CO2 utilization under mild conditions.

Understanding the aging mechanisms of lithium-ion batteries (LIBs) in real-life driving scenarios is the key to advancing battery design and management for electric vehicles. This work studies in detail the aging modes of commercial LIBs under real-life driving scenarios with a standardized World Harmonized Light Vehicle Test Cycle (WLTC) discharging procedure. Combined results from electrochemical analyses, post-mortem, and operando characterization show that a large depth of DOD (100 %) leads to significant structural changes, especially Ni-O bond length and coordination number, of NMC532 cathode materials and hence rapid degradation related to active material loss, while a low DOD level (45 %) results in intensified interfacial degradation, both leading to a limited battery cycle life (<900 and <1600 equivalent full cycles (EFCs), respectively, under 45 % and 100 % DoDs). In contrast, a medium DOD (75 %) results in balanced electrode and interface degradations and significantly enhanced cycling stability (>2200 EFCs under 75 % DoDs). Besides, we also emphasized that in real-life driving, the loss of active materials primarily originates from the cathode. These findings reveal that balancing the electrode and interfacial degradations are crucial for extending battery lifetime in practical applications. This work provides mechanistic insights into the degradation of LIBs under real-life operating conditions, guiding the rational design and optimization of cycling protocols in battery management systems (BMSs) for advanced battery development.

We studied the adsorption thermodynamics and mechanism behind the binding of nitric oxide (NO) in the interior surfaces and structural fragments of the high metal center density microporous Metal-Organic Framework (MOF) CPO-27-Cu, by gas sorption, at a series of temperatures. For the purpose of comparison, we also measured the corresponding CO2 adsorption isotherms, and as a result, the isosteric heats of adsorption for the two studied adsorptives were derived, being in the range of 12–15 kJ/mol for NO at loadings up to 0.5 NO molecules per formula unit (f.u.) of the bare compound (C4O3HCu), and 23–25 kJ/mol CO2 in the range 0–1 CO2 per f.u. Microscopically, the mode of NO binding near the square pyramid Cu(II) centers was directly accessed with the use of in situ NO gas adsorption X-ray Absorption Spectroscopy (XAS). Additionally, during the vacuum/temperature activation of the material and consequent NO adsorption, the electronic state of the Cu-species was monitored by observing the corresponding X-ray Near Edge Spectra (XANES). Contrary to the previously anticipated chemisorption mechanism for NO binding at Cu(II) species, we found that at slightly elevated temperatures, under ambient, but also cryogenic conditions, only relatively weak physisorption takes place, with no evidence for a particular adsorption preference to the coordinatively unsaturated Cu-centers of the material.

Sodium-ion batteries have not only garnered substantial attention for grid-scale energy storage owing to the higher abundance of sodium compared with lithium, but also present the possibility of fast charging because of the inherently higher sodium-ion mobility. However, it remains a phenomenal challenge to achieve a combination of these merits, given the complex structural chemistry of sodium-ion oxide materials. Here we show that O3-type sodium-ion layered cathodes (for example, Na 5/6 Li 2/27 Ni 8/27 Mn 11/27 Ti 6/27 O 2 ) have the potential to attain high power density, high energy density (260 Wh kg −1 at the electrode level) and long cycle life (capacity retention of 80% over 700 cycles in full cells). The design involves introduction of characteristic P3-structural motifs into an O3-type framework that serves to promote sodium-ion diffusivity and address detrimental transition metal migration and phase transition at a high state of charge. This study provides a principle for the rational design of sodium-ion layered oxide electrodes and advances the understanding of the composition–structure–property relationships of oxide cathode materials.

The ternary sulfido chromate (II), K-2[Cr3S4], was synthesized through a straightforward solid-state method as the first alkali metal chalcogenido chromate with the formal oxidation state +2, which was verified by X-ray absorption spectroscopy. Single-crystal diffraction analysis reveals the chromium ions to be coordinated by sulfur in two geometric arrangements: square planar and square pyramidal. Both environments are unusual for transition metal complexes with a d(4) electron configuration. Structural distortions from the ideal arrangement are present in both coordination environments. Measurement of the magnetic moment indicates a value of 3.60 mu B per chromium ion, which appears at first glance to contradict the standard ligand field theory. Quantum chemical calculations suggest high-spin states for both coordination geometries with a spin delocalization due to Cr-Cr interactions, leading to an intermediate-spin state with magnetic moment values very close to the experimental results, and attributing the structural distortions as the first example of the Jahn-Teller active d(4) system with nonoctahedral coordination geometries. The optical, dielectric, and impedance measurement results indicate the potential as a synergic insulator, capacitor, and high-dielectric-constant material.

Cation doping is an effective strategy for improving the cyclability of layered oxide cathode materials through suppression of phase transitions in the high voltage region (>~4.0V). In this study we choose Mg and Sc as representative dopants in P2- Na0.67Ni0.33Mn0.67O2. While both dopants have a positive effect on the cycling stability, they are found to influence the properties in the high voltage regime in different ways. Through a combination of RIXS, XRD, XAS, PDF analysis, and DFT, we show that it is more than just suppression of the P2 to O2 phase transition that is critical for promoting the favorable properties, and that the interplay between Ni and O activity are also critical aspects that dictate the performance. With Mg doping, we could enhance the Ni activity while simultaneously suppressing the O activity. This is surprising because it is in contrast to what has been reported in other Mn-based layered oxides where Mg is known to trigger oxygen redox. We address this contradiction by proposing a competing mechanism between Ni and Mg that impacts differences in O activity in Na0.67MgxNi0.33-xMn0.67O2 (x<0<0.33). These findings provide a new direction in understanding the effects of cation doping on the electrochemical behavior of layered oxides.

Based on previously published research, the structural response of the tetragonal hybrid perovskite crystal structure of MAPbX3 [MA: [CH3NH3]+, methylammonium; X = I, Br] to thermal expansion is reviewed here. From an averaged crystal structure perspective, the tetragonal perovskite structure of MAPbI3 and MAPbBr3, based on diffraction data, shows apparent Pb-X bond length shortening and apparent shrinkage of the [PbX6] octahedra with increasing temperature. At the same time, these apparent observations, and hence the thermal expansion, are related to the progressive phase transformation towards the cubic structure, as the lattice parameters respond to a shear stress that couples to the order parameters, and this coupling is predicted by group theory and thus aims to explain precisely the apparent negative thermal expansion-like effects. A different picture emerges for the thermal expansion when considering the very localized structure, since neither a shortening of the Pb-X bond lengths nor a shrinking of the [PbX6] octahedra is observed with pair distribution function analysis, and the presence of orthorhombic short-range order in the tetragonal and cubic perovskite structures is assumed in published studies. The compared extended X-ray absorption fine structure studies, which also map the local structure and provide the “true” bond distance, show no lead-halide bond length shortening with temperature. The perpendicular mean square relative displacement has been determined. Therefore, a comparison of the tension and bond expansion effects in both perovskites can be made. In the orthorhombic phase of MAPbI3 and MAPbBr3, positive expansion and negative tension of the lead-halide bond are almost balanced. After transitioning to the tetragonal phase, the equilibrium shifts toward negative tension. This suggests that both hybrid perovskites have tighter lead-halide bonds and less rigid [PbX6] octahedra in the tetragonal phase than in the low temperature perovskite crystal structure.

The oxygen redox reaction in lithium-rich layered oxide battery cathode materials generates extra capacity at high cell voltages (i.e., >4.5 V). However, the irreversible oxygen release causes transition metal (TM) dissolution, migration and cell voltage decay. To circumvent these issues, we introduce a strategy for tuning the Coulombic interactions in a model Li-rich positive electrode active material, i.e., Li 1.2 Mn 0.6 Ni 0.2 O 2 . In particular, we tune the Coulombic repulsive interactions to obtain an adaptable crystal structure that enables the reversible distortion of TMO 6 octahedron and mitigates TM dissolution and migration. Moreover, this strategy hinders the irreversible release of oxygen and other parasitic reactions (e.g., electrolyte decomposition) commonly occurring at high voltages. When tested in non-aqueous coin cell configuration, the modified Li-rich cathode material, combined with a Li metal anode, enables a stable cell discharge capacity of about 240 mAh g −1 for 120 cycles at 50 mA g −1 and a slower voltage decay compared to the unmodified Li 1.2 Mn 0.6 Ni 0.2 O 2 .

This article reports on studies of chlorine-substituted MAPbI3usingcombined temperature-dependent X-ray diffraction (XRD) synchrotron and Pb-L3 edgeextended X-ray absorptionfine structure (EXAFS) to analyze the anharmonicity of thelead-halide bond. The EXAFS parameters were described in the orthorhombic phaseby an Einstein or T2-type behavior, which was then compared with the experimentalEXAFS parameters of the tetragonal/cubic phase. In the orthorhombic phase, it wasobserved that the asymmetry of the pair distribution function (cumulantC3)inMAPbCl3is much lower than in MAPbI3. Compared with the behavior in theorthorhombic phase, the anharmonicity changed after the phase transition to the room-temperature phase, with MAPbCl3showing an increased anharmonicity and MAPbI3a decrease. The differences between MAPbI3and 2% chlorine substitution were small, both in the orthorhombic and tetragonal phases. By determining the structural parametersrequired to convert the effective force constantsk0andk3resulting from the EXAFS analysis into the Morse potential parameters alpha andD, we could establish that our results agree with other experimentalfindings. Moreover, using XRD, we found that the [PbX6]octahedra appear to shrink slightly in the tetragonal phase of MAPbI3and MAPbI2.94Cl0.06, toward increasing temperatures. Thisbehavior in the tetragonal phase is related to the dominant negative tension effects observed by EXAFS.

Improving the stability of electrocatalysts for the oxygen evolution reaction (OER) through materials design has received less attention than improving their catalytic activity. We explored the effect of Mn addition to a cobalt oxide for stabilizing the catalyst by comparing Na-containing CoOx and (Co0.7Mn0.3)Ox films electrodeposited in alkaline solution. The obtained disordered films were classified as layered oxides using X-ray absorption spectroscopy (XAS). The CoOx films showed a constant decrease in the catalytic activity during cycling, confirmed by oxygen detection, while that of (Co0.7Mn0.3)Ox slightly increased as measured by electrochemical metrics. These trends were rationalized based on XAS analysis of the metal oxidation states, which were Co2.8+ and Mn3.7+ near the surface after cycling. Thus, adding Mn to CoOx successfully stabilized the catalyst material and its activity during OER cycling. The development of stabilization approaches is essential to extend the durability of OER catalysts.

While the silicon-rich members of the series Cu2Zn(Ge,Si)Se4 crystallize in wurtz-kesterite type structure [1], germanium-rich samples adopt a tetrahedral structure of the kesterite type [2] (figure 1). Identification of the silicon site is straightforward from regular X-ray diffraction, as Si is a light element and has less electrons than the other cations. However, Cu, Zn, and Ge are all isoelectronic and have very similar form factors. The kesterite type of the cation distribution of Cu2ZnGeSe4 has been established by neutron diffraction [2], which can distinguish these elements.

In the field of electrochemical CO2 conversion, the development of earth-abundant catalysts which are selective for a single product is a central challenge. Cu-Sn bimetallic catalysts have been reported to yield selective CO2 reduction towards either carbon monoxide or formate. To advance the understanding of possible synergetic effects between Cu and Sn which direct product selectivity, a thorough investigation of the catalyst structure and composition in its active state is desired. We present an X-ray spectroscopy investigation of oxide-derived Cu-Sn catalysts prepared by functionalization of Cu(OH)2 nanowire arrays with ultrathin SnO2 overlayers. This method allows precisely tunable Sn composition, which enables synthesis of composite catalysts with high selectivity toward either CO or formate. Under CO2 reduction conditions, the materials undergo significant transformations before reaching their catalytically active forms. Complementary information on the electrocatalysts’ dynamic bulk and surface structure was revealed via correlating observations from multiple X-ray spectroscopy methods. In situ investigations of Cu K-edge revealed that in the bulk Cu is fully reduced from Cu2+ to Cu° after a pre reduction step. Quasi in situ XPS demonstrated that, at the catalyst surface, Cu is also present exclusively as Cu°, whereas significant differences in Sn quantification and speciation were observed between the CO- and formate-selective catalysts. After CO2 electrolysis, CO-selective catalysts exhibited a surface Sn content of 13 at. % predominantly present as Sn oxide, while the formate-selective catalysts had a Sn content of ~70 at. % consisting of both metallic Sn° and Sn oxide species. Our study reveals the complex dependence of catalyst structure, composition, and speciation with applied electrochemical bias in Sn-functionalized nanostructured Cu catalysts.

We report the synthesis of Ni/SiOCN ceramic nanocomposites with high surface area as catalysts for carbon dioxide and methane conversion.