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SrLi2Ti6O14 (SLTO) coated with different amount of ZrO2 was successfully prepared. The as-obtained composites are stacked by a series of particles with a pure phase structure and a good crystallinity. Furthermore, ZrO2 coating not only enhances the structural stability of the materials but also facilitates the diffusion of lithium through the SEI film. As a result, the redox polarization was reduced, and the reversibility of the electrochemical reaction was enhanced. Particularly, SLTO-ZrO2-2 sample delivers a high initial lithiation capacity of 283.6 mA h g−1, and the values maintain at 251.7, 228.0, 207.4, 175.3, and 147.7 mA h g−1 at the current densities of 0.13, 0.26, 0.54, 1.31, and 2.62 A g−1, respectively. Our experiment also confirmed that SLTO materials coated with ZrO2 are suitable for high power density applications, and the lithiation specific energy efficiency of SLTO-ZrO2-2 is 200% as high as that of pure SLTO at a power density of 1257 W kg−1.

Graphical abstract CDs are utilized as crucial structure-directing agents to elaborately design 3D cross-linked rod-like structured Bi2Se3/CDs composites. Computational simulations combined with experiments demonstrate that such robust 3D framework and the existence of interface Bi-O-C bond can simultaneously enhance the intrinsic sluggish kinetics and structural stability, endowing Bi2Se3/CDs anode with fast-charging capability and durable cycling life. Download : Download high-res image (205KB) Download : Download full-size image Advanced electrode materials for fast-charging lithium-ion batteries are of great significance to next-generation energy-storage systems. Herein, three-dimensional (3D) hierarchical rod-structured Bi2Se3/carbon dots (Bi2Se3/CDs) composite is elaborately designed for fast-kinetics lithium storage. It is proposed that CDs-induced self-assembly growth and site-selective ion-exchange transform nanosheets into cross-linked architecture. Such robust 3D framework provides efficient channels for electron/ion transport and sufficient inner space for volume variation as confirmed by theoretical prediction. Notably, the existence of interface Bi-O-C bond would effectively enhance its inherent bulk electronic conductivity and accelerate ionic transportation by narrowing the bandgap and reducing the Li+ migration energy barriers. Consequently, intrinsic sluggish kinetics and structural stability are simultaneously improved, endowing Bi2Se3/CDs composite electrode fast charging/discharging capability of 165 mAh g−1 at 20 A g−1 (corresponding to charge in ≈27 s) and excellent long-term durability with the capacity of 502 mAh g−1 over 950 cycles at 1 A g−1. Moreover, the intercalation-conversion-alloying type lithium storage mechanism of Bi2Se3/CDs is revealed by in-situ XRD. This work provides a train of thoughts for other CDs-tailored composites with tunable morphology and structure.

We successfully form the solid solutions YbMnxFe2-xO4 for x = 0.25, 0.50, 0.75, and 1.0 in order to study the mechanism of oxygen release and uptake as a function of Mn substitution. High-resolution synchrotron x-ray diffraction (SXRD) reveals that YbMnxFe2-xO4 readily uptakes oxygen and undergoes a structural transition from R-3m to P-3 to become the hyper-stoichiometric YbMnxFe2-xO4.5, which demonstrates their potential as oxygen storage materials. X-ray photoelectron spectroscopy (XPS) implies Mn2+ and Fe2+ oxidize to Mn3+ and Fe3+ after the structural transition. Thermogravimetric analysis (TGA) as well as in situ SXRD measurements at elevated temperatures show that O2 uptake commences at 200 ⁰C but the structural transition not until 300 ⁰C. The structural evolution under methane and air, monitored by in situ SXRD, implies promising reversibility and structural stability in this series. By performing structural refinements, we find that Mn substitution causes the lattice parameters, a and c, to evolve in a diametric fashion. Strongly anisotropic expansion of the lattice occurs in all the reduced phases YbMnxFe2-xO4 (R-3m) and oxidized phases YbMnxFe2-xO4.5 (P-3). We propose that this phenomenon can be attributed to d-electron filling and crystal field effects for the Mn and Fe cations.

Anionic redox reaction (ARR) in layered manganese-based oxide cathodes has been considered as an effective strategy to improve the energy density of sodium-ion batteries. Mn-vacancy layered oxides deliver a high ARR-related capacity with small voltage hysteresis, however, they are limited by rapid capacity degradation and poor rate capability, which arise from inferior structure changes due to repeated redox of lattice oxygen. Herein, redox-inactive Ti4+ is introduced to substitute partial Mn4+ to form Na2Ti0.5Mn2.5O7 (Na4/7[□1/7Ti1/7Mn5/7]O2, □ for Mn vacancies), which can effectively restrain unfavorable interlayer gliding of Na2Mn3O7 at high charge voltages, as reflected by an ultralow-strain volume variation of 0.11%. There is no irreversible O2 evolution observed in Na2Ti0.5Mn2.5O7 upon charging, which stabilizes the lattice oxygen and ensures the overall structural stability. It exhibits increased capacity retention of 79.1% after 60 cycles in Na2Ti0.5Mn2.5O7 (17.1% in Na2Mn3O7) and good rate capability (92.1 mAh g-1 at 0.5 A g-1). This investigation provides new insights into designing high-performance cathode materials with reversible ARR and structural stability for SIBs.

Alkali aluminosilicates are potential materials for high temperature applications under alkali load. This study investigated the corrosion behaviour of potassium aluminosilicates of the nominal compositions of KAlSi2O6 and KAlSiO4 synthesized at different temperatures and dwell times and exposed to alkali load at 1100 °C. For understanding the corrosion behaviour depending on the synthesizing parameters, the produced materials and corroded samples were investigated by XRD and NMR spectroscopy (29Si, 27Al). The combination of both analytical techniques showed that characteristics of the synthesized materials on a structural level played an important role for the corrosion behaviour. It was shown that amorphous and disordered components in the samples occurred which were not registered by XRD. The application of 29Si and 27Al NMR spectroscopy yielded that materials having already after synthesis a structural arrangement similar to the equilibrium target phase of the batch showed a high structural stability under alkali load and gave positive results in the applied corrosion test. Materials with large structural rearrangements during alkali load exhibited volume changes and therefore failed the corrosion test. Based on these observations it should therefore be possible to design materials with high chemical and mechanical stability suitable as furnace linings and to evaluate end-of-life aluminosilicates for an application as alkali corrosion resistant recyclates.

The Cesium-based variant perovskites are emerging aspirants for optoelectronic and thermoelectric applications. We have comprehensively studied and executed calculations for the analysis of optical and transport characteristics of new family of variant perovskites Cs2XI6 (X = Ti, Zr, Hf). The structural stability has been confirmed by Goldsmith tolerance factor. Energy band gap calculations revealed a direct band gap for the studied materials, that increases from 1.41 eV to 2.35 eV and 2.92 eV by the replacement of Ti by Zr and Hf. The maximum absorption is found to move from visible to ultraviolet region by replacement of Zr and Hf. This ensures their importance for solar cells. Also, the transport characteristics are evaluated for temperature 0–400 K and chemical potential from −0.15 eV to 0.25 eV. The high thermoelectric efficiency has been reported for Cs2HfI6 from the studied compounds.

Nanomaterials are intended for industrial applications, for that purpose scalability needs to be addressed, therefore an important issue comes to the picture: storage. Graphene oxide (GO) is of great interest for practical applications in optoelectronics, chemical sensors, supercapacitor electrodes, among others. GO properties are related to its O/C ratio and its precise control allows fine tuning of properties such as conductivity, chemical reactivity and band gap. Nevertheless, GO has a critical storage restriction, due to its chemical self‐reduction, that is, the oxygen loss not only alters its properties, but also promotes aggregation through time. In this work, the impact of storage conditions on GO properties was studied by comparing two systems: a solid sample and a liquid dispersion, which were analyzed during the course of 3 years. For this purpose, stability, O/C ratio and optical band‐gap of the stored samples were analyzed through time by means of zeta potential, X‐ray photoelectron spectroscopy (XPS) and UV‐Vis. Results show the difference in stability between the samples due to oxygen loss in the GO structure, confirmed by XPS. Moreover, optical band‐gap shows that the solid sample decreases its value around 64% compared to the liquid dispersion.

Although transition-metal-based phosphides as cost-effective catalysts have great potential for transforming water to hydrogen, their electrocatalytic property for industrial application is still limited. Herein, we focus on developing amorphous NiCoP with dandelion-like arrays anchored on nanowires through a universal strategy of hydrothermal and phosphorization. The hierarchical structure features in larger catalytic surface areas expedited reaction kinetics and improved structural stability. Benefiting from these merits, the NiCoP reaches 10 mA cm-2 at an overpotential of mere 57 mV for a hydrogen evolution reaction in standard solution. Also, a profound activity for the generation of oxygen is along with it, which requires 276 mV to attain 10 mA cm-2. Moreover, it demonstrates satisfying durability for both processes.

Despite the synthesis and structural characterization of closo-hydroborate dianions, [Bn Hn ]2- (n=6-12) more than 50 years ago, some ambiguity remains about the structure of [B8 H8 ]2- . Although the solid-state structure of [B8 H8 ]2- was established by single-crystal X-ray studies in 1969, fast rearrangements in solution at accessible temperatures prevented its detailed characterization. We therefore stabilized a derivative of [B8 H8 ]2- by using Cp2 MBH3 and structurally characterized two new octaborane analogues, [(Cp2 MBH3 )2 B8 H6 ] (Cp=η5 -C5 H5 ; M=Zr (1-Zr) and Hf (1-Hf)), so that the dynamics of the B8 skeleton were arrested. The solid-state structures of both 1-Zr and 1-Hf comprise a dodecahedron core protected by {Cp2 MBH3 } moieties on both sides of the cluster. Spectroscopic characterization (11 B NMR) validates the intactness of the B8 dodecahedron core in solution as well. Theoretical calculations establish that the two exo-{Cp2 MBH3 } fragments provide structural and electronic structural stability to the B8 core and its intact dodecahedral dianionic nature. Furthermore, we propose isodesmic equations for the formation of higher analogues of the Bn core (n>8) guarded by different group 4 transition metals. Our analysis suggests that, as we move to higher polyhedra (n>10), the formation becomes unfavourable irrespective of metal.

Lithium-rich layered oxides have received great attention due to their high energy density as cathode material. However, the progressive structural transformation from layered to spinel phase triggered by transition-metal migration and the irreversible release of lattice oxygen leads to voltage fade and capacity decay. Here, we report a Fe, Cl codoped and Co-free Li-rich layered cathode with significantly improved structural stability. It is revealed that the Fe and Cl codoping can facilitate the Li-ion diffusion and improve the rate performance of the materials. Moreover, the calculations show that the structural stability is enhanced by Fe and Cl codoping. As a result, the Fe and Cl codopant reduces the irreversible release of lattice oxygen, mitigates voltage fade, and improves the first-cycle Coulombic efficiency. This work provides a low-cost, environmentally friendly, practical strategy for high-performance cathode materials.

LiNi0.8Co0.1Mn0.1O2 cathode material for lithium-ion battery exhibits high capacity, but it suffers from interfacial side reactions and structural/thermodynamic instability, which leads to capacity reduction and safety problems. Cubic brick (Ni0.8Co0.1Mn0.1)C2O4·2H2O particles with micron size are synthesized by co-precipitation method. The oxalic precursor is sintered with lithium hydroxide to obtain cubic mono-dispersion LiNi0.8Co0.1Mn0.1O2 micrometer particles. Structural stability, cycling performance, rate capability and compacting density of the cubic mono-dispersion material are investigated. Conventional spherical and irregular mono-dispersion LiNi0.8Co0.1Mn0.1O2 are also prepared for comparison. The results reveal that the cubic mono-dispersion LiNi0.8Co0.1Mn0.1O2 dramatically enhances the structural stability and cycling performance at a little cost of capacity and rate capability.

Li-rich Mn-based cathodes have attracted much attention due to their high capacity stemming from anion redox above 4.5 V. However, the continuous activation of Li2MnO3 in Li-rich Mn-based materials, which correlates with O2 release and TM migration, is usually unfavorable to structural stability. Herein, based on a gas-solid interface reaction, we tackle this continuous activation phenomenon by restricting the capacity release of Li2MnO3 via NH4HCO3 treatment in the Li1.2Ni0.36Mn0.44O2 cathode. After modification, oxygen vacancies associated with the spinel phase are introduced on the surface. The 4 mol % NH4HCO3-modified material's capacity starts at 182 mAh g-1 at 1 C instead of increasing from 173 to 186 mAh g-1 for 25 cycles in the pristine material. Meanwhile, it also exhibits an excellent capacity retention of 93.24% after 200 cycles (at 1 C), with a small voltage decay rate of 1.19 mV cycle-1.

Electrochemical cycling induces transition-metal (TM) ion migration and oxygen vacancy formation in layered transition-metal oxides, thus causing performance decay. Here, a combination of ab initio calculations and atomic level imaging is used to explore the TM migration mechanisms in LiNi1/3Mn1/3Co1/3O2 (NMC333). For the bulk model, TM/Li exchange is an favorable energy pathway for TM migration. For the surface region with the presence of oxygen vacancies, TM condensation via substitution of Li vacancies (TMsub) deciphers the frequently observed TM segregation phenomena in the surface region. Ni migrates much more easily in both the bulk and surface regions, highlighting the critical role of Ni in stabilizing layered cathodes. Moreover, once TM ions migrate to the Li layer, it is easier for TM ions to diffuse and form a TM-enriched surface layer. The present study provides vital insights into the potential paths to tailor layered cathodes with a high structural stability and superior performance.

Although the TM3Si silicides play an important role in transition metal silicides high-temperature materials, the hydrogenated mechanism of the cubic TM3Si is entirely unclear. To explore the hydrogenated mechanism, in this work, we apply the first-principles calculations to study the influence of hydrogen on the structural stability, mechanical and thermodynamic properties of TM3Si silicides. Based on the structural characteristic, four TM3Si silicides (Mo3Si, Nb3Si, Cr3Si and W3Si) and three hydrogen occupied models were considered. In particular, the influence of hydrogen on the stability, elastic properties, hardness, brittle-or-ductile behavior and Debye temperature of TM3Si was investigated. The result shows that the hydrogen is a thermodynamic stability in TM3Si because of the electronic interaction between hydrogen and TM3Si silicides. The thermodynamic stability of the hydrogenated TM3Si follows the order of Nb3Si

In this paper, three tetrahedral nanocages, composed of six DNA double helix edges with all having the twist number 1, 2 or 3, have been characterized using classical molecular dynamics simulation to measure the specific structural and conformational features produced by only changing the twisting number of each double helix. The simulation result indicates that three tetrahedral cages are relatively stable and are maintained along the entire trajectory. Each double helix is more inclined to behave as a whole in the 2TD and 3TD cages than in the 1TD cage according to the cross-correlation maps for three nanocages, and also their local motions are more easily induced by the conformational variability of the thymidine linkers due to the increased flexibility of each helix. Hence, the double helices become the important factors on the structural stability of total cages with the DNA twisting number, and also give the signification contributions to the sizes of these cages conferring the larger spaces of the 2TD and 3TD cages than the 1TD cage. Our result provides an insight into which roles the double helix edges play in assembling DNA polyhedron, and also contribute to improving the loading capacity of DNA tetrahedron in drug delivery.

To increase the service life of rechargeable batteries, transition metal oxide hosts with high structural stability for the intercalation of carrier ions are important. Herein, we reconstruct the crystal structure of a commercial V2O5 by pre-intercalating H+ and H2O pillars using a facile hydrothermal reaction and obtain a bi-layer structured H0.642V2O5·0.143H2O (HVO) as an excellent host for aqueous Zn-ion batteries. Benefiting from the structural reconstruction, the irreversible “layer-to-amorphous” phase evolution during cycling is considerably less, resulting in ultra-high cycling stability of HVO with nearly no capacity fading even after 500 cycles at a current density of 0.5 A g−1. Moreover, a synthetic proton and Zn2+ intercalation mechanism in the HVO host is demonstrated. This work provides both a facile synthesis method for the preparation of V-based compounds and a new viewpoint for achieving high-performance host materials.

Regardless of the manufacturing process such as solid-state reaction, sol-gel, etc., applied in obtaining anodes in solid oxide fuel cells (SOFCs), Sr2MgMoO6-δ (SMMO) double perovskites are recognized worldwide and widely used as anodic material with potential application in SOFC. This is due to several factors such as high electronic conductivity, high electrocatalytic activity, structural stability under reducing atmosphere, high transition temperature, giant magnetoresistance, reasonable tolerance to carbon formation, and its desired ability to reduce sulfur poisoning. In this review article, the advances of the SMMO double perovskite are analyzed.

Li-rich layered oxides (LLOs) are promising cathode materials for Li-ion batteries owing to their high capacities (>250 mAh g-1), however, they suffered from severe capacity and voltage fading caused by irreversible oxygen loss and phase changes. Herein, the structural stability of single crystalline and polycrystalline Li1.14Ni0.32Mn0.44Co0.04O2 was compared in detail. It was found that the stability of oxidized oxygen ions on the near surface was improved in single crystals, which retarded oxygen loss from surface and surficial phase changes, possibly owing to the facet regulating and low surface curvature. In addition, the formation-migration of Mn3+, one of the crucial factors that caused capacity fading of LLOs, can be mitigated by increasing Ni3+ ratio. Under the synergistic effect of low oxygen defects on the near surface and high Ni3+ ratio, stable cycling performances and higher thermal stability were obtained.

We present structural stability of new lightweight complex hydrides: Li2BeMgH6, LiNaMg2H6, and LiNaBeMgH6, which correlated to the LiMgH3 (R3c) phase. Lattice dynamic stability, mechanical stability, electronic structure, and hydrogen vacancy mechanism are investigated using ab initio calculation. Remarkably, calculation results show the enhancement of the internal mechanism for hydrogen storage in the lightweight complex hydrides. The stable phase (R3) of the new complex hydrides exhibits high gravimetric density and low heat capacity. The Li2BeMgH6 in the R3 phase systematically indicates the remarkable improvement of the hydrogen storage mechanism compared with the LiMgH3-based system.

This work revisits the topological characterization of the Diels–Alder reaction between 1,3–butadiene and ethylene. In contrast to the currently accepted rationalization, we here provide strong evidence in support of a representation in terms of seven structural stability domains separated by a sequence of 10 elementary catastrophes, but all only of the fold type, i.e., C4H6 + C2H4 : 1–7– [FF]F[F†F†][F†F†][FF]F†–0 : C6H10. Such an unexpected finding provides fundamental new insights opening simplifying perspectives concerning the rationalization of the CC bond formation in pericyclic reactions in terms of the simplest Thom’s elementary catastrophe, namely the one–(state) variable, one–(control) parameter function.

Layered oxides as the cathode materials of sodium-ion batteries are receiving extensive attention due to their high capacity and flexible composition. However, the layered cathode tends to be thermodynamically and electrochemically unstable during sodiation and de-sodiation. Herein, we for the first time propose the "pinning effect" and controllable "pinning point" in sodium storage layered cathodes to enhance the structural stability and achieve the optimal electrochemical performance. 0%, 2.5% and 7.3% transition-metal (TM) occupancies in Na-site as pinning points are obtained through adjusting the feeding ratio of iron in Na 0.67 Mn 0.5 Co 0.5- x Fe x O 2 system. Results show that 2.5% TM pinning is beneficial to restrain the potential slab sliding and enhance the structural stability, resulting in an ultra-low volume variation of 0.6% and maintaining the smooth two-dimensional channel for Na-ion transfer. Finally, the Na 0.67 Mn 0.5 Co 0.4 Fe 0.1 O 2 cathode with the optimal TM pinning delivers outstanding cycling performance of over 1000 cycles and superior rate capability up to 10C.

Large-scale distributed thermal storage requires high-energy-density and low-cost thermal storage materials. Here, a concocted composite composed of Al2(SO4)3·18H2O and FeSO4·7H2O salts, as well as...

The certified power conversion efficiency of state-of-the-art organic–inorganic hybrid perovskite solar cells has surpassed 25%, showing promising potential for commercialization. Compared with vol...

In recent years, dynamic shock wave-driven investigation carried out on the crystallographic phase stabilities of nano-materials has led to the accumulation of massive explosion of innovations which materialize in identifying the efficient materials so that such kinds of assessments are highly required before putting them into practical applications. Surprisingly, at shocked conditions, most of the materials are found to have undergone phase transition or a variety of changes have been observed in their stability as well as efficiency. Hence, device engineers are highly focused on the search of high shock-resistant materials for applications point of view especially for aerospace, defense, and military applications. In the present context, we have chosen one of the most familiar divalent metal ferrites of cubic copper ferrite nanocrystalline material (CuFe2O4 NPs) for the analysis of structural stability and the results have been screened by X-ray diffraction (XRD) as well as ultra-violet diffuse reflectance spectroscopic (UV-DRS) techniques. Magnetic phase stability has been evaluated by vibrating sample magnetometer (VSM). Interestingly, the title ferrite does not experience any crystallographic and magnetic phase transition even though it has polymorphic nature and variety of magnetic states. Therefore, it could be confirmed that CuFe2O4 NPs have considerable shock-resistant behavior for both crystallographic and magnetic phases. The results are discussed in the upcoming sections.

The charge transport between layers of layered double hydroxide (LDH) with structural stability is generally considered as a key factor in restricting electrochemical performances. Herein, we repor...

P2-type Na0.67Mn0.75Fe0.25O2 cathode materials with low cost and high specific capacity have aroused much interest for sodium-ion batteries. Nevertheless, the cyclic and structural stabilities need...

Layered transition metal oxides are ideal Na+/K+ host materials due to their high theoretical capacities and appropriate working potentials, and the pursuit of cost-effective and environmentally friendly alternatives with high energy density and structural stability has remained a hot topic. Herein, we design and synthesize a low-cost and zero-strain cathode material, P3-type K0.4Fe0.1Mn0.8Ti0.1O2, which demonstrates superior properties for both potassium and sodium storage. The cathode delivers a reversible potassium storage capacity of 117 mA h g-1 at 20 mA g-1 and a fast rate capability of 71 mA h g-1 at 1000 mA g-1. In situ X-ray diffraction reveals a solid-solution transition with a negligible volume change of 0.5% upon K+ insertion/deinsertion that ensures long cycling stability over 300 cycles. When the material is employed for sodium storage, a spontaneous ion-exchange process with Na+-containing electrolytes occurs. Thanks to the positive effects of the remaining K+ ions that protect the layered structure from collapse as well as expand the interlayer structure, and the resulting K0.12Na0.28Fe0.1Mn0.8Ti0.1O2 demonstrates a high sodium storage capacity of 160 mA h g-1 and superior cycling stability with capacity retention of 81% after 300 cycles as well as fast kinetics.