This study presents a novel approach to enhance silicon anode performance through barium titanate(BTO)incorporation,with the establishment of a force-electric coupling model.By introducing piezoelectric BTO into silic...This study presents a novel approach to enhance silicon anode performance through barium titanate(BTO)incorporation,with the establishment of a force-electric coupling model.By introducing piezoelectric BTO into silicon matrices,we successfully improved both the mechanical stability and electrochemical kinetics of the anode.The developed force-electric coupling model explains how BTO mitigates stress accumulation during lithiation while optimizing the kinetics of Li^(+)and electron transfer.Experimental verification and multiphysical simulation indicate that Si@BTO effectively eliminates structural degradation during the cycling process and significantly reduces the charge transfer resistance.The force-electric coupling mechanism further facilitates stable solid electrolyte interphase(SEI)formation.When paired with LiFePO_(4)cathodes,Si@BTO maintains 76% capacity retention after 500 cycles at a 10 C rate.This work establishes a basic force-electric coupling model framework and offers insights into the development of advanced silicon anode batteries with exceptional performance.展开更多
Layered-type transition metal(TM)oxides are considered as one of the most promising cathodes for K-ion batteries because of the large theoretical gravimetric capacity by low molar mass.However,they suffer from severe ...Layered-type transition metal(TM)oxides are considered as one of the most promising cathodes for K-ion batteries because of the large theoretical gravimetric capacity by low molar mass.However,they suffer from severe structural change by de/intercalation and diffusion of K^(+)ions with large ionic size,which results in not only much lower reversible capacity than the theoretical capacity but also poor power capability.Thus,it is important to enhance the structural stability of the layered-type TM oxides for outstanding electrochemical behaviors under the K-ion battery system.Herein,it is investigated that the substitution of the appropriate Ti^(4+)contents enables a highly enlarged reversible capacity of P3-type KxCrO_(2) using combined studies of first-principles calculation and various experiments.Whereas the pristine P3-type KxCrO_(2) just exhibits the reversible capacity of∼120 mAh g^(−1) in the voltage range of 1.5-4.0 V(vs.K^(+)/K),the∼0.61 mol K^(+)corresponding to∼150 mAh g^(−1) can be reversible de/intercalated at the structure of P3-type K0.71[Cr_(0.75)Ti_(0.25)]O_(2) under the same conditions.Furthermore,even at the high current density of 788 mA g^(−1),the specific capacity of P3-type K0.71[Cr_(0.75)Ti_(0.25)]O_(2) is∼120 mAh g^(−1),which is∼81 times larger than that of the pristine P3-type KxCrO_(2).It is believed that this research can provide an effective strategy to improve the electrochemical performances of the cathode materials suffered by severe structural change that occurred during charge/discharge under not only K-ion battery system but also other rechargeable battery systems.展开更多
NH_(4)V_(4)O_(10)(NVO)as a cathode material of zincion battery is prone to collapse in the repeated process of embedding and de-embedding of Zn^(2+),and its application is limited by the instability of the material.He...NH_(4)V_(4)O_(10)(NVO)as a cathode material of zincion battery is prone to collapse in the repeated process of embedding and de-embedding of Zn^(2+),and its application is limited by the instability of the material.Here,calciumdoped ammonium vanadate(CNVO)is successfully synthesized via a one-step hydrothermal approach.The intercalated Ca2+in NVO serves as a firm pillar between the[VO_n]layers to maintain the structure stability during the ion insertion/extraction process.Furthermore,density functional theory(DFT)calculations and ex situ experiments reveal that CNVO demonstrates higher affinity and conductivity compared to NVO,which can effectively improve the kinetics of Zn^(2+)diffusion,reduce the electrostatic repulsion of Zn^(2+)during intercalation and deintercalation,and maintaining the stability of the layered structure.As a result,the CNVO material demonstrates outstanding electrochemical performance,delivering a specific capacity of 183 m Ah·g^(-1)at 5 A·g^(-1).Moreover,it sustains an impressive 91%capacity retention after 1300 cycles.展开更多
Previous studies have demonstrated that increasing Fe doping content can enhance the saturation magnetization and maximum energy product of 2:17-type Sm-Co rare-earth permanent magnets.Howeve r,syste matic theo retica...Previous studies have demonstrated that increasing Fe doping content can enhance the saturation magnetization and maximum energy product of 2:17-type Sm-Co rare-earth permanent magnets.Howeve r,syste matic theo retical calculations and the effects of other transition metal dopants have yet to be explored.This study employed first-principles computational methods to investigate the effects of doping with 3d and Zr transition metal elements on the structural stability,magnetic properties,and electronic structure of Sm_(2)Co_(17)permanent magnets.The results indicate that Sc and Zr tend to occupy the Sm-6c site,while Ni,Cu and Zn preferentially occupy the 18h site,and Ti,V,Cr,Mn and Fe primarily occupy the Co-6c site.Except for V and Cu,all other elements effectively improve the structural stability of the doped systems.Additionally,Mn and Fe doping can significantly enhance the total magnetic moment and magnetocrystalline anisotropy energies of the Sm_(2)Co_(17)system,while Cr only increases the total magnetic moment.More importantly,doping with Cr,Mn and Fe within the doping co ntent range of9.8 at%<x<35.29 at% can simultaneously improve the structural stability,total magnetic moment and magnetocrystalline anisotropy energy of the Sm_(2)Co_(17) system.Our study provides valuable theoretical guidance for experimental exploration and is expected to promote the development and application of novel rare-earth permanent magnetic materials.展开更多
The rapid expansion of the automotive sector has significantly increased the demand for highperformance lithium-ion batteries,positioning Ni-rich layered cathodes as a promising solution due to their high energy densi...The rapid expansion of the automotive sector has significantly increased the demand for highperformance lithium-ion batteries,positioning Ni-rich layered cathodes as a promising solution due to their high energy density and cost-efficiency.However,these cathodes face critical challenges,including thermal instability and structural degradation at an elevated temperature,which hinder their practical application.This study introduces an advanced surface reconstruction strategy combining a LiScF_(4)coating,Sc/F surface co-doping,and a cation-mixing layer to address these issues.The LiScF_(4)coating serves as a durable protective barrier,reducing electrolyte decomposition,minimizing transition metal dissolution,and enhancing lithium-ion transport.Sc/F surface co-doping stabilizes lattice oxygen by increasing the energy barrier for oxygen vacancy formation and minimizing oxygen release,thereby suppressing phase transitions and interfacial side reactions.Additionally,the cation-mixing layer improves interfacial stability by alleviating lattice strain and supporting reversible cation migration,ensuring prolonged durability during cycling and under high-temperature conditions.These integrated modifications work synergistically to mitigate various degradation mechanisms,significantly improving the thermal stability,structural integrity,and electrochemical performance of Ni-rich cathodes.This approach offers a viable pathway for incorporating Ni-rich cathodes into advanced lithium-ion batteries,making them well-suited for applications requiring high thermal stability.Moreover,this research provides valuable guidance for the development of a multi-component modification strategy,paving the way for future innovations in energy storage materials and advancing high-performance battery technology.展开更多
The structural stability, elastic and electronic properties under pressure at 0 K for β-Ti have been investigated by per-forming first-principles calculations. With the increase of pressure, the structure of β-Ti b...The structural stability, elastic and electronic properties under pressure at 0 K for β-Ti have been investigated by per-forming first-principles calculations. With the increase of pressure, the structure of β-Ti becomes stabler, which is further con-firmed by the calculation for density of state （DOS）. The phase transition pressure of is about 64. 3 GPa, which is consist-ent with other theoretical predictions （63. 7 GPa） and the experimental result （50 GPa）. The pressure dependence of elastic constants shows that the low-pressure limit for a mechanically stable β-Ti is about 50 GPa with low Young？s modulus value of about 30. 01 GPa, which approaches the value of a human bone （30 GPa）. In addition, the pressure dependence of bulk modu-lus B, shear modulus G, Young’s modulus E,Poisson’s ratio σ,aggregate sound velocities,and ductility/brittleness under different pressures were also discussed. B, G and E ascend monotonously with increasing pressure, while a descends. β-Ti re-mains ductile by analysis of B/G under considered pressures.展开更多
A variety of problems in operations research, performance analysis, manufacturing, and communication networks, etc., can be modelled as discrete event systems with minimum and maximum constraints. When such systems re...A variety of problems in operations research, performance analysis, manufacturing, and communication networks, etc., can be modelled as discrete event systems with minimum and maximum constraints. When such systems require only maximum constraints （or dually, only minimum constraints）, they can be studied using linear methods based on max-plus algebra. Systems with mixed constraints are called min-max systems in which rain, max and addition operations appear simultaneously. A significant amount of work on such systems can be seen in literature. In this paper we provide some new results with regard to the balance problem of min-max functions; these are the structure properties of min-max systems. We use these results in the structural stabilization. Our main results are two sufficient conditions for the balance and one sufficient condition for the structural stabilization. The block technique is used to analyse the structure of the systems. The proposed methods, based on directed graph and max-plus algebra are constructive in nature. We provide several examples to demonstrate how the methods work in practice.展开更多
To synergistically recover alumina and alkali from red mud(RM),the structural stability and conversion mechanism of hydroandradite(HA)from hydrogarnet(HG)were investigated via the First-principles,XRF,XRD,PSD and SEM ...To synergistically recover alumina and alkali from red mud(RM),the structural stability and conversion mechanism of hydroandradite(HA)from hydrogarnet(HG)were investigated via the First-principles,XRF,XRD,PSD and SEM methods,and a novel hydrothermal process based on the conversion principle was finally proposed.The crystal structure simulation shows that the HA with varied silicon saturation coefficients is more stable than HG,and the HA with a high iron substitution coefficient is more difficult to be converted from HG.The(110)plane of Fe_(2)O_(3) is easier to combine with HG to form HA,and the binding energy is 81.93 kJ/mol.The effects of raw material ratio,solution concentration and hydrothermal parameters on the conversion from HG to HA were revealed,and the optimal conditions for the alumina recovery were obtained.The recovery efficiencies of alumina and Na_(2)O from the RM are 63.06%and 97.34%,respectively,and the Na_(2)O content in the treated RM is only 0.13%.展开更多
Prussian blue analogs(PBAs)are considered one of the excellent cathode materials for sodium-ion batteries due to their low cost and high theoretical specific capacity,especially sodium-rich iron-based PBAs(FeHCF)can p...Prussian blue analogs(PBAs)are considered one of the excellent cathode materials for sodium-ion batteries due to their low cost and high theoretical specific capacity,especially sodium-rich iron-based PBAs(FeHCF)can provide higher energy density.FeHCF has a poor charge/discharge platform stability at high voltages(FeC_(6)moiety),which is mainly affected by its coordination environment.In this research,Cu^(+)(six-coordinated),which is close to the ionic radius of Fe^(2+),was used for substitution,the FeC_(6)vacancies of FeHCF were reduced,and the coordination environment was optimized.The low Cu^(+)-substituted FeHCF(Cu^(+)0.625)has an optimal electrochemical performance at 8.5 mA/g with a reversible specific capacity of 142 mA h/g and FeC_(6)moiety contribution of more than 68 mA h/g,which is superior to that of unmodified and other Cu^(2+)-substituted FeHCFs.In situ tests demonstrate the reversible structural stability of the Cu^(+)0.625,supporting the stability of their high-voltage platform capacity.This Cu^(+)substitution strategy further enriches the approach to optimize the coordination environment of sodium-rich FeHCF.展开更多
Ammonium-ion hybrid supercapacitors(A-HSCs)have emerged as promising candidates for next-generation energy storage owing to their inherent safety and environmental sustainability.Hexagonal tungsten oxide(h-WO_(3)),wit...Ammonium-ion hybrid supercapacitors(A-HSCs)have emerged as promising candidates for next-generation energy storage owing to their inherent safety and environmental sustainability.Hexagonal tungsten oxide(h-WO_(3)),with its well-defined tunnel structure,holds great promise as a negative electrode material for NH^(4+)storage.However,its practical application is hindered by structural instability and poor intrinsic electrical conductivity.To address these challenges,a dual-regulation strategy is proposed,integrating molybdenum(Mo)doping and NH^(4+)pre-intercalation to concurrently optimize the tunnel structure and electronic environment of h-WO_(3)(Mo-NWO).Comprehensive experimental and theoretical analyses reveal that Mo doping narrows the bandgap of WO_(3)and reduces the diffusion energy barrier,thereby accelerating NH^(4+)adsorption and diffusion.Simultaneously,NH^(4+)pre-intercalation stabilizes the tunnel framework via hydrogen bonding,ensuring structural reversibility.As expected,the Mo-NWO/AC electrode achieves a high areal capacitance of 13.6 F cm^(−2)at 5 mA cm^(−2)and retains 80.14%of its capacitance after 5000 cycles,demonstrating exceptional rate capability and cycling stability.Moreover,the assembled Mn_(3)O_(4)//Mo-NWO/AC device delivers a high energy density of 3.41 mWh cm^(−2)and outstanding long-term stability(85.75%retention after 12,000 cycles).This work provides a viable strategy for designing high-performance NH^(4+)storage materials and advances the development of sustainable energy storage systems.展开更多
TiNb_(2)O_(7)represents an up-and-coming anode material for fast-charging lithium-ion batteries,but its practicalities are severely impeded by slow transfer rates of ionic and electronic especially at the low-temperat...TiNb_(2)O_(7)represents an up-and-coming anode material for fast-charging lithium-ion batteries,but its practicalities are severely impeded by slow transfer rates of ionic and electronic especially at the low-temperature conditions.Herein,we introduce crystallographic engineering to enhance structure stability and promote Li+diffusion kinetics of TiNb_(2)O_(7)(TNO).The density functional theory computation reveals that Ti^(4+)is replaced by Sb^(5+)and Nb^(5+)in crystal lattices,which can reduce the Li+diffusion impediment and improve electronic conductivity.Synchrotron radiation X-ray 3D nano-computed tomography and in situ X-ray diffraction measurement confirm the introduction of Sb/Nb alleviates volume expansion during lithiation and delithiation processes,contributing to enhancing structure stability.Extended X-ray absorption fine structure spectra results verify that crystallographic engineering also increases short Nb-O bond length in TNO-Sb/Nb.Accordingly,the TNO-Sb/Nb anode delivers an outstanding capacity retention rate of 89.8%at 10 C after 700 cycles and excellent rate performance(140.4 mAh g^(−1) at 20 C).Even at−30℃,TNO-Sb/Nb anode delivers a capacity of 102.6 mAh g^(−1) with little capacity degeneration for 500 cycles.This work provides guidance for the design of fast-charging batteries at low-temperature condition.展开更多
The AHP-GDM model is used for the assessment of structural stability, with the Bohai Sea area as an exam- ple. In this model, the credit degree of each expert is calculated through the assessment matrix based on the s...The AHP-GDM model is used for the assessment of structural stability, with the Bohai Sea area as an exam- ple. In this model, the credit degree of each expert is calculated through the assessment matrix based on the similarity and diversity of vector. The comprehensive opinions of expert panel are quantitatively obtained by considering the effect ofcredit degree. According to the geological structural setting, the Bohai Sea is di- vided into twelve assessment zones of structural stability by non-uniform element method. The structural stability grade of each zone is obtained on the basis of the latest geophysical data, earthquake statistical data, and the information of fault activities, current stress field and crustal deformation. The results show that there are one relatively stable area, three relatively sub-stable areas, six relatively sub-unstable areas and two relatively unstable areas. The assessment results of non-uniform element method are very close with those of uniform grid method with size of 0.25 in longitude direction and 0.14 in latitude direction. However the workload of non-uniform element method is only 1 / 16 of the latter. Compared with traditional assessment methods of structural stability, a more objective and reliable assessment result can be obtained by combining non-uniform element method and AHP-GDM model.展开更多
Electronic structure and elastic properties of MgCu_(2),Mg_(2)Ca and MgZn_(2)phases were investigated by means of first-principles calculations from CASTEP program based on density functional theory(DFT).The calculate...Electronic structure and elastic properties of MgCu_(2),Mg_(2)Ca and MgZn_(2)phases were investigated by means of first-principles calculations from CASTEP program based on density functional theory(DFT).The calculated lattice parameters were in good agreement with the experimental and literature values.The calculated heats of formation and cohesive energies shown that MgCu_(2)has the strongest alloying ability and structural stability.The elastic constants of MgCu_(2),Mg_(2)Ca and MgZn_(2)phases were calculated,the bulk moduli,shear moduli,Young's moduli and Poisson's ratio were derived.The calculated results shown that MgCu_(2),Mg_(2)Ca and MgZn_(2)are all ductile phases.Among the three phases,MgCu_(2)has the strongest stiffness and the plasticity of MgZn_(2)phase is the best.The density of states(DOS),Mulliken electron occupation number and charge density difference of MgCu_(2),Mg_(2)Ca and MgZn_(2)phases were discussed to analyze the mechanism of structural stability and mechanical properties.展开更多
Ni-rich layered oxides are the preferred cathode materials for high-energy-density lithium-ion batteries currently used in electric vehicles.In this paper,we present a systematic first-principles evaluation of the dei...Ni-rich layered oxides are the preferred cathode materials for high-energy-density lithium-ion batteries currently used in electric vehicles.In this paper,we present a systematic first-principles evaluation of the deintercalation process in the Li1-xNiO2-ySy.The partial density of states(PDOS)characters of the electrons near the Fermi level,redox behaviors,and thermal stability have been investigated within the GGA+U scheme.The results show that the introduction of sulfur alleviates the lattice distortion during charging,suppresses nickel migration,and enhances the stability of oxygen according to the contribution of sulfur anion redox to the charge compensation for the overcharged Li1-xNiO2-ySy.This study provides a new insight on improving the stability of Ni-rich cathode materials by tuning of the electrochemical behaviors based on sulfur anion redox.展开更多
The structural stabilities and electronic structures of Ga atomic chains are studied by the first-principles plane wave pseudopotential method based on the density functional theory. The present calculations show that...The structural stabilities and electronic structures of Ga atomic chains are studied by the first-principles plane wave pseudopotential method based on the density functional theory. The present calculations show that gallium can form planar chains in linear-, zigzag- and ladder-form one-dimensional structures. The most stable one among the studied structures is the zigzag chain with a unit cell rather close to equilateral triangles with four nearest neighbors, and all the other structures are metastable. The relative structural stability, the energy bands and the charge densities are discussed based on the ab initio calculations and the Jahn-Teller effect.展开更多
The structural stability of methane hydrate under pressure at room temperature was examined by both in-situ single-crystal and powder X-ray diffraction techniques on samples with structure types I, II, and H in diamon...The structural stability of methane hydrate under pressure at room temperature was examined by both in-situ single-crystal and powder X-ray diffraction techniques on samples with structure types I, II, and H in diamond-anvil ceils. The diffraction data for types II （slI） and H （sH） were refined to the known structures with space groups Fd3m and P63/mmc, respectively. Upon compression, sl methane hydrate transforms to the sll phase at 120 MPa, and then to the sH phase at 600 MPa. The slI methane hydrate was found to coexist locally with sI phase up to 500 MPa and with sH phase up to 600 MPa. The pure sH structure was found to be stable between 600 and 900 MPa. Methane hydrate decomposes at pressures above 3 GPa to form methane with the orientationally disordered Fm3m structure and ice VII （Pn3m）. The results highlight the role of vip （CH4）-host （H2O） interactions in the stabilization of the hydrate structures under pressure.展开更多
Alloy nanoparticles exhibit higher catalytic activity than monometallic nanoparticles, and their stable structures are of importance to their applications. We employ the simulated annealing algorithm to systematically...Alloy nanoparticles exhibit higher catalytic activity than monometallic nanoparticles, and their stable structures are of importance to their applications. We employ the simulated annealing algorithm to systematically explore the stable structure and segregation behavior of tetrahexahedral Pt–Pd–Cu–Au quaternary alloy nanoparticles. Three alloy nanoparticles consisting of 443 atoms, 1417 atoms, and 3285 atoms are considered and compared. The preferred positions of atoms in the nanoparticles are analyzed. The simulation results reveal that Cu and Au atoms tend to occupy the surface, Pt atoms preferentially occupy the middle layers, and Pd atoms tend to segregate to the inner layers. Furthermore, Au atoms present stronger surface segregation than Cu ones. This study provides a fundamental understanding on the structural features and segregation phenomena of multi-metallic nanoparticles.展开更多
The structural stability and electrical properties of AlB2-type MnB2 were studied based on high pressure angledispersive x-ray diffraction, in situ electrical resistivity measured in a diamond anvil cell(DAC) and firs...The structural stability and electrical properties of AlB2-type MnB2 were studied based on high pressure angledispersive x-ray diffraction, in situ electrical resistivity measured in a diamond anvil cell(DAC) and first-principles calculations under high pressure. The x-ray diffraction results show that the structure of AlB2-type MnB2 remains stable up to 42.6 GPa. From the equation of state of MnB2, we obtained a bulk modulus value of 169.9±3.7 GPa with a fixed pressure derivative of 4, which indicates that AlB2-type MnB2 is a hard and incompressible material. The electrical resistance undergoes a transition at about 19.3 GPa, which can be explained by a transition of manganese 3d electrons from localization to delocalization under high pressure.展开更多
The energetic and electronic structures of precipitates on the Cu-rich side of Cu-Ni-Si alloys were investigated by using the first-principle calculations based on plane-wave pseudopotential method.The negative format...The energetic and electronic structures of precipitates on the Cu-rich side of Cu-Ni-Si alloys were investigated by using the first-principle calculations based on plane-wave pseudopotential method.The negative formation heats and the cohesive energies of these precipitates were estimated with electronic structure calculations, and their structural stability was also analyzed.The results show thatδ-Ni2Si,γ-Ni5Si2 andβ-Ni3Si precipitates all have great alloying ability and structural stability,which,after comparing their density of states （DOS）,is found attributed to the pseudogap effect near the Fermi level（Ef）and strong hybridization between the Ni-3d and Si-3p states.Compared with the other two precipitates,theδ-Ni2Si precipitate has the greatest structural stability,which is resulted from its lower DOS at Ef and the main bonding peaks slightly moving to the low energy region.展开更多
We pioneered a study about how the geometric relationship of single-walled carbon nanotubes(SWCNT) is influenced by curvature factor and non-planar geometry factor in cylindrical coordinate system based on the assumpt...We pioneered a study about how the geometric relationship of single-walled carbon nanotubes(SWCNT) is influenced by curvature factor and non-planar geometry factor in cylindrical coordinate system based on the assumption of complete symmetry. The bond length and angle of every carbon-carbon bonds are determined by using the principle of the minimum energy. The results of the paper include(1) From the calculation result, the symmetry breaking appears for chiral carbon nanotubes, while the part symmetry appears for achiral carbon nanotubes with increasing curvature.(2) The synergistic effect of bond lengths and bond angles is first found.(3) We conclude that the influence of non-planar geometry factor can be completely ignored on bond lengths and bond angles when the curvature parameter has been included in the model.(4)The two fractal dimensions are given from the nanoscale to the macroscale for zigzag topology and armchair topology respectively. Fractal dimensions of SWCNT show special characteristics, varying with the length of SWCNT until the lengths approach infinity. The close and inevitable correlations among curvature, symmetry breaking and stability of SWCNTs can be summed up as: the increase of curvature causes symmetry breaking,and such symmetry breaking will further reduce the structural stability.展开更多
基金the financial support of the National Natural Science Foundation of China(NSFC,No.12074093)。
文摘This study presents a novel approach to enhance silicon anode performance through barium titanate(BTO)incorporation,with the establishment of a force-electric coupling model.By introducing piezoelectric BTO into silicon matrices,we successfully improved both the mechanical stability and electrochemical kinetics of the anode.The developed force-electric coupling model explains how BTO mitigates stress accumulation during lithiation while optimizing the kinetics of Li^(+)and electron transfer.Experimental verification and multiphysical simulation indicate that Si@BTO effectively eliminates structural degradation during the cycling process and significantly reduces the charge transfer resistance.The force-electric coupling mechanism further facilitates stable solid electrolyte interphase(SEI)formation.When paired with LiFePO_(4)cathodes,Si@BTO maintains 76% capacity retention after 500 cycles at a 10 C rate.This work establishes a basic force-electric coupling model framework and offers insights into the development of advanced silicon anode batteries with exceptional performance.
基金Korea Institute of Materials Science,Grant/Award Number:PNK9370National Research Foundation of Korea,Grant/Award Numbers:NRF-2021R1A2C1014280,NRF-2022R1C1C1011058,NRF-2022M3H446401037201Korea Institute of Science and Technology,Grant/Award Number:2E32581-23-092。
文摘Layered-type transition metal(TM)oxides are considered as one of the most promising cathodes for K-ion batteries because of the large theoretical gravimetric capacity by low molar mass.However,they suffer from severe structural change by de/intercalation and diffusion of K^(+)ions with large ionic size,which results in not only much lower reversible capacity than the theoretical capacity but also poor power capability.Thus,it is important to enhance the structural stability of the layered-type TM oxides for outstanding electrochemical behaviors under the K-ion battery system.Herein,it is investigated that the substitution of the appropriate Ti^(4+)contents enables a highly enlarged reversible capacity of P3-type KxCrO_(2) using combined studies of first-principles calculation and various experiments.Whereas the pristine P3-type KxCrO_(2) just exhibits the reversible capacity of∼120 mAh g^(−1) in the voltage range of 1.5-4.0 V(vs.K^(+)/K),the∼0.61 mol K^(+)corresponding to∼150 mAh g^(−1) can be reversible de/intercalated at the structure of P3-type K0.71[Cr_(0.75)Ti_(0.25)]O_(2) under the same conditions.Furthermore,even at the high current density of 788 mA g^(−1),the specific capacity of P3-type K0.71[Cr_(0.75)Ti_(0.25)]O_(2) is∼120 mAh g^(−1),which is∼81 times larger than that of the pristine P3-type KxCrO_(2).It is believed that this research can provide an effective strategy to improve the electrochemical performances of the cathode materials suffered by severe structural change that occurred during charge/discharge under not only K-ion battery system but also other rechargeable battery systems.
基金supported by the National Natural Science Foundation of China(No.51602193)ClassⅢPeak Discipline of Shanghai-Materials Science and Engineering(High-Energy Beam Intelligent Processing and Green Manufacturing)UK Research and Innovation(UKRI)under the UK government’s Horizon Europe funding guarantee(No.101077226,EP/Y008707/1)
文摘NH_(4)V_(4)O_(10)(NVO)as a cathode material of zincion battery is prone to collapse in the repeated process of embedding and de-embedding of Zn^(2+),and its application is limited by the instability of the material.Here,calciumdoped ammonium vanadate(CNVO)is successfully synthesized via a one-step hydrothermal approach.The intercalated Ca2+in NVO serves as a firm pillar between the[VO_n]layers to maintain the structure stability during the ion insertion/extraction process.Furthermore,density functional theory(DFT)calculations and ex situ experiments reveal that CNVO demonstrates higher affinity and conductivity compared to NVO,which can effectively improve the kinetics of Zn^(2+)diffusion,reduce the electrostatic repulsion of Zn^(2+)during intercalation and deintercalation,and maintaining the stability of the layered structure.As a result,the CNVO material demonstrates outstanding electrochemical performance,delivering a specific capacity of 183 m Ah·g^(-1)at 5 A·g^(-1).Moreover,it sustains an impressive 91%capacity retention after 1300 cycles.
基金Project supported by the National Key R&D Program of China(2022YFB3505301)the National Key R&D Program of Shanxi Province(202302050201014)+2 种基金the National Natural Science Foundation of China(12304148)the Natural Science Basic Research Program of Shanxi Province(202203021222219)the China Postdoctoral Science Foundation(2023M731452)。
文摘Previous studies have demonstrated that increasing Fe doping content can enhance the saturation magnetization and maximum energy product of 2:17-type Sm-Co rare-earth permanent magnets.Howeve r,syste matic theo retical calculations and the effects of other transition metal dopants have yet to be explored.This study employed first-principles computational methods to investigate the effects of doping with 3d and Zr transition metal elements on the structural stability,magnetic properties,and electronic structure of Sm_(2)Co_(17)permanent magnets.The results indicate that Sc and Zr tend to occupy the Sm-6c site,while Ni,Cu and Zn preferentially occupy the 18h site,and Ti,V,Cr,Mn and Fe primarily occupy the Co-6c site.Except for V and Cu,all other elements effectively improve the structural stability of the doped systems.Additionally,Mn and Fe doping can significantly enhance the total magnetic moment and magnetocrystalline anisotropy energies of the Sm_(2)Co_(17)system,while Cr only increases the total magnetic moment.More importantly,doping with Cr,Mn and Fe within the doping co ntent range of9.8 at%<x<35.29 at% can simultaneously improve the structural stability,total magnetic moment and magnetocrystalline anisotropy energy of the Sm_(2)Co_(17) system.Our study provides valuable theoretical guidance for experimental exploration and is expected to promote the development and application of novel rare-earth permanent magnetic materials.
基金supported by the National Natural Science Foundation of China(22179008)support from the Beijing Nova Program(20230484241)+1 种基金support from the China Postdoctoral Science Foundation(2024M754084)the Postdoctoral Fellowship Program of CPSF(GZB20230931)。
文摘The rapid expansion of the automotive sector has significantly increased the demand for highperformance lithium-ion batteries,positioning Ni-rich layered cathodes as a promising solution due to their high energy density and cost-efficiency.However,these cathodes face critical challenges,including thermal instability and structural degradation at an elevated temperature,which hinder their practical application.This study introduces an advanced surface reconstruction strategy combining a LiScF_(4)coating,Sc/F surface co-doping,and a cation-mixing layer to address these issues.The LiScF_(4)coating serves as a durable protective barrier,reducing electrolyte decomposition,minimizing transition metal dissolution,and enhancing lithium-ion transport.Sc/F surface co-doping stabilizes lattice oxygen by increasing the energy barrier for oxygen vacancy formation and minimizing oxygen release,thereby suppressing phase transitions and interfacial side reactions.Additionally,the cation-mixing layer improves interfacial stability by alleviating lattice strain and supporting reversible cation migration,ensuring prolonged durability during cycling and under high-temperature conditions.These integrated modifications work synergistically to mitigate various degradation mechanisms,significantly improving the thermal stability,structural integrity,and electrochemical performance of Ni-rich cathodes.This approach offers a viable pathway for incorporating Ni-rich cathodes into advanced lithium-ion batteries,making them well-suited for applications requiring high thermal stability.Moreover,this research provides valuable guidance for the development of a multi-component modification strategy,paving the way for future innovations in energy storage materials and advancing high-performance battery technology.
基金International Cooperation Project of the Ministry of Science and Technology of China(No.2014DFA50320)National Natural Science Foundation of China(Nos.51674226,51574207,51574206,51274175)+1 种基金International Science and Technology Cooperation Project of Shanxi Province(No.2015081041)Research Project Supported by Shanxi Scholarship Council of China(No.2016-Key 2)
文摘The structural stability, elastic and electronic properties under pressure at 0 K for β-Ti have been investigated by per-forming first-principles calculations. With the increase of pressure, the structure of β-Ti becomes stabler, which is further con-firmed by the calculation for density of state （DOS）. The phase transition pressure of is about 64. 3 GPa, which is consist-ent with other theoretical predictions （63. 7 GPa） and the experimental result （50 GPa）. The pressure dependence of elastic constants shows that the low-pressure limit for a mechanically stable β-Ti is about 50 GPa with low Young？s modulus value of about 30. 01 GPa, which approaches the value of a human bone （30 GPa）. In addition, the pressure dependence of bulk modu-lus B, shear modulus G, Young’s modulus E,Poisson’s ratio σ,aggregate sound velocities,and ductility/brittleness under different pressures were also discussed. B, G and E ascend monotonously with increasing pressure, while a descends. β-Ti re-mains ductile by analysis of B/G under considered pressures.
基金This work was supported by National Natural Science of China (No.69874040) the National Key Project of China, and the Hundred Talents Program of the Chinese Academy of Sciences.
文摘A variety of problems in operations research, performance analysis, manufacturing, and communication networks, etc., can be modelled as discrete event systems with minimum and maximum constraints. When such systems require only maximum constraints （or dually, only minimum constraints）, they can be studied using linear methods based on max-plus algebra. Systems with mixed constraints are called min-max systems in which rain, max and addition operations appear simultaneously. A significant amount of work on such systems can be seen in literature. In this paper we provide some new results with regard to the balance problem of min-max functions; these are the structure properties of min-max systems. We use these results in the structural stabilization. Our main results are two sufficient conditions for the balance and one sufficient condition for the structural stabilization. The block technique is used to analyse the structure of the systems. The proposed methods, based on directed graph and max-plus algebra are constructive in nature. We provide several examples to demonstrate how the methods work in practice.
基金the financial support from the National Key R&D Program of China(No.2022YFC2904405)the National Natural Science Foundation of China(Nos.22078055,51774079)。
文摘To synergistically recover alumina and alkali from red mud(RM),the structural stability and conversion mechanism of hydroandradite(HA)from hydrogarnet(HG)were investigated via the First-principles,XRF,XRD,PSD and SEM methods,and a novel hydrothermal process based on the conversion principle was finally proposed.The crystal structure simulation shows that the HA with varied silicon saturation coefficients is more stable than HG,and the HA with a high iron substitution coefficient is more difficult to be converted from HG.The(110)plane of Fe_(2)O_(3) is easier to combine with HG to form HA,and the binding energy is 81.93 kJ/mol.The effects of raw material ratio,solution concentration and hydrothermal parameters on the conversion from HG to HA were revealed,and the optimal conditions for the alumina recovery were obtained.The recovery efficiencies of alumina and Na_(2)O from the RM are 63.06%and 97.34%,respectively,and the Na_(2)O content in the treated RM is only 0.13%.
基金supported by the Key Talent Project of Gansu Province(2025RCXM017)the National Natural Science Foundation of China(52261040)+2 种基金the Postgraduate Innovation Star Program of Gansu Province(2025CXZX-476)the Major Science and Technology Project of Gansu Province(22ZD6GA008)the Innovation Driven Assistance Engineering Project of Gansu Association for Science and Technology(GXH20250325-5).
文摘Prussian blue analogs(PBAs)are considered one of the excellent cathode materials for sodium-ion batteries due to their low cost and high theoretical specific capacity,especially sodium-rich iron-based PBAs(FeHCF)can provide higher energy density.FeHCF has a poor charge/discharge platform stability at high voltages(FeC_(6)moiety),which is mainly affected by its coordination environment.In this research,Cu^(+)(six-coordinated),which is close to the ionic radius of Fe^(2+),was used for substitution,the FeC_(6)vacancies of FeHCF were reduced,and the coordination environment was optimized.The low Cu^(+)-substituted FeHCF(Cu^(+)0.625)has an optimal electrochemical performance at 8.5 mA/g with a reversible specific capacity of 142 mA h/g and FeC_(6)moiety contribution of more than 68 mA h/g,which is superior to that of unmodified and other Cu^(2+)-substituted FeHCFs.In situ tests demonstrate the reversible structural stability of the Cu^(+)0.625,supporting the stability of their high-voltage platform capacity.This Cu^(+)substitution strategy further enriches the approach to optimize the coordination environment of sodium-rich FeHCF.
基金supported by the National Natural Science Foundation of Guangxi Province(2024GXNSFBA010033)the Special Fund for Science and Technology Development of Guangxi(Grant No.AD25069078).
文摘Ammonium-ion hybrid supercapacitors(A-HSCs)have emerged as promising candidates for next-generation energy storage owing to their inherent safety and environmental sustainability.Hexagonal tungsten oxide(h-WO_(3)),with its well-defined tunnel structure,holds great promise as a negative electrode material for NH^(4+)storage.However,its practical application is hindered by structural instability and poor intrinsic electrical conductivity.To address these challenges,a dual-regulation strategy is proposed,integrating molybdenum(Mo)doping and NH^(4+)pre-intercalation to concurrently optimize the tunnel structure and electronic environment of h-WO_(3)(Mo-NWO).Comprehensive experimental and theoretical analyses reveal that Mo doping narrows the bandgap of WO_(3)and reduces the diffusion energy barrier,thereby accelerating NH^(4+)adsorption and diffusion.Simultaneously,NH^(4+)pre-intercalation stabilizes the tunnel framework via hydrogen bonding,ensuring structural reversibility.As expected,the Mo-NWO/AC electrode achieves a high areal capacitance of 13.6 F cm^(−2)at 5 mA cm^(−2)and retains 80.14%of its capacitance after 5000 cycles,demonstrating exceptional rate capability and cycling stability.Moreover,the assembled Mn_(3)O_(4)//Mo-NWO/AC device delivers a high energy density of 3.41 mWh cm^(−2)and outstanding long-term stability(85.75%retention after 12,000 cycles).This work provides a viable strategy for designing high-performance NH^(4+)storage materials and advances the development of sustainable energy storage systems.
基金supported by the National Natural Science Foundation of China(22279026,2247090373)the Natural Science Foundation of Chongqing(CSTB2022NSCQ-MSX1401)+2 种基金the China Postdoctoral Science Foundation(2024M764198)the National Natural Science Foundation of China(22509044)the Fundamental Research Funds for the Central Universities(grant no.HIT.OCEF.2022017).
文摘TiNb_(2)O_(7)represents an up-and-coming anode material for fast-charging lithium-ion batteries,but its practicalities are severely impeded by slow transfer rates of ionic and electronic especially at the low-temperature conditions.Herein,we introduce crystallographic engineering to enhance structure stability and promote Li+diffusion kinetics of TiNb_(2)O_(7)(TNO).The density functional theory computation reveals that Ti^(4+)is replaced by Sb^(5+)and Nb^(5+)in crystal lattices,which can reduce the Li+diffusion impediment and improve electronic conductivity.Synchrotron radiation X-ray 3D nano-computed tomography and in situ X-ray diffraction measurement confirm the introduction of Sb/Nb alleviates volume expansion during lithiation and delithiation processes,contributing to enhancing structure stability.Extended X-ray absorption fine structure spectra results verify that crystallographic engineering also increases short Nb-O bond length in TNO-Sb/Nb.Accordingly,the TNO-Sb/Nb anode delivers an outstanding capacity retention rate of 89.8%at 10 C after 700 cycles and excellent rate performance(140.4 mAh g^(−1) at 20 C).Even at−30℃,TNO-Sb/Nb anode delivers a capacity of 102.6 mAh g^(−1) with little capacity degeneration for 500 cycles.This work provides guidance for the design of fast-charging batteries at low-temperature condition.
基金The National High Technology Research and Development Program of China(863Program)under contract Nos 2009AA093401 and 2010AA09Z302the National Natural Science Foundation of China(Key Program)under contract No.90814011+1 种基金Special Funds for Postdoctoral Innovative Projects of Shandong Province under contract No.201102008the Fundamental Research Funds for the Central Universities under contract No.11CX04037A
文摘The AHP-GDM model is used for the assessment of structural stability, with the Bohai Sea area as an exam- ple. In this model, the credit degree of each expert is calculated through the assessment matrix based on the similarity and diversity of vector. The comprehensive opinions of expert panel are quantitatively obtained by considering the effect ofcredit degree. According to the geological structural setting, the Bohai Sea is di- vided into twelve assessment zones of structural stability by non-uniform element method. The structural stability grade of each zone is obtained on the basis of the latest geophysical data, earthquake statistical data, and the information of fault activities, current stress field and crustal deformation. The results show that there are one relatively stable area, three relatively sub-stable areas, six relatively sub-unstable areas and two relatively unstable areas. The assessment results of non-uniform element method are very close with those of uniform grid method with size of 0.25 in longitude direction and 0.14 in latitude direction. However the workload of non-uniform element method is only 1 / 16 of the latter. Compared with traditional assessment methods of structural stability, a more objective and reliable assessment result can be obtained by combining non-uniform element method and AHP-GDM model.
基金This work is supported by National Key Technology Research and Development Program of Ministry of Science and Technology of China(2011BAE22B00)Program for Liaoning Innovative Research Team in University.
文摘Electronic structure and elastic properties of MgCu_(2),Mg_(2)Ca and MgZn_(2)phases were investigated by means of first-principles calculations from CASTEP program based on density functional theory(DFT).The calculated lattice parameters were in good agreement with the experimental and literature values.The calculated heats of formation and cohesive energies shown that MgCu_(2)has the strongest alloying ability and structural stability.The elastic constants of MgCu_(2),Mg_(2)Ca and MgZn_(2)phases were calculated,the bulk moduli,shear moduli,Young's moduli and Poisson's ratio were derived.The calculated results shown that MgCu_(2),Mg_(2)Ca and MgZn_(2)are all ductile phases.Among the three phases,MgCu_(2)has the strongest stiffness and the plasticity of MgZn_(2)phase is the best.The density of states(DOS),Mulliken electron occupation number and charge density difference of MgCu_(2),Mg_(2)Ca and MgZn_(2)phases were discussed to analyze the mechanism of structural stability and mechanical properties.
文摘Ni-rich layered oxides are the preferred cathode materials for high-energy-density lithium-ion batteries currently used in electric vehicles.In this paper,we present a systematic first-principles evaluation of the deintercalation process in the Li1-xNiO2-ySy.The partial density of states(PDOS)characters of the electrons near the Fermi level,redox behaviors,and thermal stability have been investigated within the GGA+U scheme.The results show that the introduction of sulfur alleviates the lattice distortion during charging,suppresses nickel migration,and enhances the stability of oxygen according to the contribution of sulfur anion redox to the charge compensation for the overcharged Li1-xNiO2-ySy.This study provides a new insight on improving the stability of Ni-rich cathode materials by tuning of the electrochemical behaviors based on sulfur anion redox.
基金ACKN0WLEDGMENT This work was supported by the National Natural Science Foundation of China （No.10374076） and the Natural Science Foundation of Fujian Province （No.E0320001）.
文摘The structural stabilities and electronic structures of Ga atomic chains are studied by the first-principles plane wave pseudopotential method based on the density functional theory. The present calculations show that gallium can form planar chains in linear-, zigzag- and ladder-form one-dimensional structures. The most stable one among the studied structures is the zigzag chain with a unit cell rather close to equilateral triangles with four nearest neighbors, and all the other structures are metastable. The relative structural stability, the energy bands and the charge densities are discussed based on the ab initio calculations and the Jahn-Teller effect.
基金HPSynC is supported as part of EFree,an EnergyFrontier Research Center funded by the U.S.Department of Energy(DOE),Office of Science, Office of Basic Energy Sciences(BES) under Award Number DE-SC0001057HPCAT is supported by CIW,CDAC,UNLV and LLNL through funding from DOE-NNSA,DOE-BES and NSFAPS is supported by DOE-BES,under Contract No.DE-AC02-06CH 11357
文摘The structural stability of methane hydrate under pressure at room temperature was examined by both in-situ single-crystal and powder X-ray diffraction techniques on samples with structure types I, II, and H in diamond-anvil ceils. The diffraction data for types II （slI） and H （sH） were refined to the known structures with space groups Fd3m and P63/mmc, respectively. Upon compression, sl methane hydrate transforms to the sll phase at 120 MPa, and then to the sH phase at 600 MPa. The slI methane hydrate was found to coexist locally with sI phase up to 500 MPa and with sH phase up to 600 MPa. The pure sH structure was found to be stable between 600 and 900 MPa. Methane hydrate decomposes at pressures above 3 GPa to form methane with the orientationally disordered Fm3m structure and ice VII （Pn3m）. The results highlight the role of vip （CH4）-host （H2O） interactions in the stabilization of the hydrate structures under pressure.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51271156,11474234,and 61403318)the Natural Science Foundation of Fujian Province of China(Grant Nos.2013J01255 and 2013J06002)
文摘Alloy nanoparticles exhibit higher catalytic activity than monometallic nanoparticles, and their stable structures are of importance to their applications. We employ the simulated annealing algorithm to systematically explore the stable structure and segregation behavior of tetrahexahedral Pt–Pd–Cu–Au quaternary alloy nanoparticles. Three alloy nanoparticles consisting of 443 atoms, 1417 atoms, and 3285 atoms are considered and compared. The preferred positions of atoms in the nanoparticles are analyzed. The simulation results reveal that Cu and Au atoms tend to occupy the surface, Pt atoms preferentially occupy the middle layers, and Pd atoms tend to segregate to the inner layers. Furthermore, Au atoms present stronger surface segregation than Cu ones. This study provides a fundamental understanding on the structural features and segregation phenomena of multi-metallic nanoparticles.
基金Project supported by the National Basic Research Program of China （Grant No. 2011CB808200）, the Program for Changjiang Scholars and Innovative Re- search Team in University, China （Grant No. IRT1132）, the National Natural Science Foundation of China （Grant Nos. 51032001, 11074090, 10979001, and 51025206）, and the U.S. Department of Energy, Office of Science, and Office of Basic Energy Sciences （Grant No. DE-AC02-98CH 10886）.
文摘The structural stability and electrical properties of AlB2-type MnB2 were studied based on high pressure angledispersive x-ray diffraction, in situ electrical resistivity measured in a diamond anvil cell(DAC) and first-principles calculations under high pressure. The x-ray diffraction results show that the structure of AlB2-type MnB2 remains stable up to 42.6 GPa. From the equation of state of MnB2, we obtained a bulk modulus value of 169.9±3.7 GPa with a fixed pressure derivative of 4, which indicates that AlB2-type MnB2 is a hard and incompressible material. The electrical resistance undergoes a transition at about 19.3 GPa, which can be explained by a transition of manganese 3d electrons from localization to delocalization under high pressure.
基金the National Natural Science Foundation of China(No.50571035)the National High Technology Research and Development Project(863) of China(No.2006AA032528)
文摘The energetic and electronic structures of precipitates on the Cu-rich side of Cu-Ni-Si alloys were investigated by using the first-principle calculations based on plane-wave pseudopotential method.The negative formation heats and the cohesive energies of these precipitates were estimated with electronic structure calculations, and their structural stability was also analyzed.The results show thatδ-Ni2Si,γ-Ni5Si2 andβ-Ni3Si precipitates all have great alloying ability and structural stability,which,after comparing their density of states （DOS）,is found attributed to the pseudogap effect near the Fermi level（Ef）and strong hybridization between the Ni-3d and Si-3p states.Compared with the other two precipitates,theδ-Ni2Si precipitate has the greatest structural stability,which is resulted from its lower DOS at Ef and the main bonding peaks slightly moving to the low energy region.
基金National Natural Science Foundation of China (No. 10602028)Student Research Train Program of BeiHang University
文摘We pioneered a study about how the geometric relationship of single-walled carbon nanotubes(SWCNT) is influenced by curvature factor and non-planar geometry factor in cylindrical coordinate system based on the assumption of complete symmetry. The bond length and angle of every carbon-carbon bonds are determined by using the principle of the minimum energy. The results of the paper include(1) From the calculation result, the symmetry breaking appears for chiral carbon nanotubes, while the part symmetry appears for achiral carbon nanotubes with increasing curvature.(2) The synergistic effect of bond lengths and bond angles is first found.(3) We conclude that the influence of non-planar geometry factor can be completely ignored on bond lengths and bond angles when the curvature parameter has been included in the model.(4)The two fractal dimensions are given from the nanoscale to the macroscale for zigzag topology and armchair topology respectively. Fractal dimensions of SWCNT show special characteristics, varying with the length of SWCNT until the lengths approach infinity. The close and inevitable correlations among curvature, symmetry breaking and stability of SWCNTs can be summed up as: the increase of curvature causes symmetry breaking,and such symmetry breaking will further reduce the structural stability.
