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
LiNixCoyMn_(2)O_(2)(NCM,x≥0.8,x+y+z=1)cathodes have attracted much attention due to their high specific capacity and low cost.However,severe anisotropic volume changes and oxygen evolution induced capacity decay and ...LiNixCoyMn_(2)O_(2)(NCM,x≥0.8,x+y+z=1)cathodes have attracted much attention due to their high specific capacity and low cost.However,severe anisotropic volume changes and oxygen evolution induced capacity decay and insecurity have hindered their commercial application at scale.In order to overcome these challenges,a kind of tantalum(Ta)doped nickel-rich cathode with reduced size and significantly increased number of primary particles is prepared by combining mechanical fusion with high temperature co-calcination.The elaborately designed micro-morphology of small and uniform primary particles effectively eliminates the local strain accumulation caused by the random orientation of primary particles.Moreover,the uniform distribution of small primary particles stabilizes the spherical secondary particles,thus effectively inhibiting the formation and extension of microcracks.In addition,the formed strong Ta-O bonds restrain the release of lattice oxygen,which greatly increases the structural stability and safety of NCM materials.Therefore,the cathode material with the designed primary particle morphology shows superior electrochemical performance.The 1 mol%Ta-modified cathode(defined as1%Ta-NCM)shows a capacity retention of 97.5%after 200 cycles at 1 C and a rate performance of 137.3 mAh g^(-1)at 5 C.This work presents promising approach to improve the structural stability and safety of nickel-rich NCM.展开更多
Fiber is highly escapable in conventional slickwater,making it difficult to form fiber-proppant agglomerate with proppant and exhibit limited effectiveness.To solve these problems,a novel structure stabilizer(SS)is de...Fiber is highly escapable in conventional slickwater,making it difficult to form fiber-proppant agglomerate with proppant and exhibit limited effectiveness.To solve these problems,a novel structure stabilizer(SS)is developed.Through microscopic structural observations and performance evaluations in indoor experiments,the mechanism of proppant placement under the action of the SS and the effects of the SS on proppant placement dimensions and fracture conductivity were elucidated.The SS facilitates the formation of robust fiber-proppant agglomerates by polymer,fiber,and quartz sand.Compared to bare proppants,these agglomerates exhibit reduced density,increased volume,and enlarged contact area with the fluid during settlement,leading to heightened buoyancy and drag forces,ultimately resulting in slower settling velocities and enhanced transportability into deeper regions of the fracture.Co-injecting the fiber and the SS alongside the proppant into the reservoir effectively reduces the fiber escape rate,increases the proppant volume in the slickwater,and boosts the proppant placement height,conveyance distance and fracture conductivity,while also decreasing the proppant backflow.Experimental results indicate an optimal SS mass fraction of 0.3%.The application of this SS in over 80 wells targeting tight gas,shale oil,and shale gas reservoirs has substantiated its strong adaptability and general suitability for meeting the production enhancement,cost reduction,and sand control requirements of such wells.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
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
With the aim to further improve the mechanical properties of Mg-A1-RE-based alloy, Mg-3.0Al-1.8Ce-0.3Y-0.2Mn alloy was prepared by high-pressure die-casting technique. The microstructure, thermal stability of intermet...With the aim to further improve the mechanical properties of Mg-A1-RE-based alloy, Mg-3.0Al-1.8Ce-0.3Y-0.2Mn alloy was prepared by high-pressure die-casting technique. The microstructure, thermal stability of intermetallic phases and mechanical properties were investigated. The results show that the alloy is composed of fine primary a-Mg dendrites and eutectic in the interdendritic regions. The intermetallic phases in eutectic are Aln（Ce,Y）3 and A12（Ce,Y） with the former being the dominant one. The thermal stability of Al11（ce,Y）3 is conditioned. It is basically stable at temperature up to 200℃ within 800 h, while most of the Al11（Ce,Y）3 intermetallics transform to A12（Ce,Y） at higher temperature of 450 ℃ for 800 h. The alloy exhibits remarkably improved strength both at room temperature and 200℃, which is mainly attributed to the reinforcement of dendrite boundaries with Alll（Ce,Y）3 intermetallics, small dendritic arm spacing effect as well as the solid solution strengthening with Y element.展开更多
Lithium ion power batteries have undoubtedly become one of the most promising rechargeable batteries at present;nonetheless,they still suffer from the challenges such as requirement of even higher energy density and c...Lithium ion power batteries have undoubtedly become one of the most promising rechargeable batteries at present;nonetheless,they still suffer from the challenges such as requirement of even higher energy density and capacity retention.Nickel-rich layer oxides(Ni≥0.8)become ideal cathode materials to achieve the high specific capacity.Integration of optimization of synthesis process and modification of crystal structure to suppress the capacity fading can obviously improve the performance of the lithium ion batteries.This review presents the recent modification strategies of the nickel-rich layered oxide materials.Unlike in previous reviews and related papers,the specific mechanism about each type of the modification strategies is specially discussed in detail,which is mainly about inhibiting the anisotropic lattice strain and adjusting the cation mixing degree to maintain crystal structure.Based on the recent progress,the prospects and challenges of the modified nickel-rich layer cathodes to upgrade the property of lithium ion batteries are also comprehensively analyzed,and the potential applications in the field of plug-in hybrid vehicles and electric vehicles are further discussed.展开更多
This paper brings forward the concept of stability of the spatial structure of urban agglomeration(UA)based on Central Place Theory by introducing centrality index and fractal theory.Before assessment,K=4 is selected ...This paper brings forward the concept of stability of the spatial structure of urban agglomeration(UA)based on Central Place Theory by introducing centrality index and fractal theory.Before assessment,K=4 is selected as parameter to calculate centrality index and fractal dimension(K represents the quantitive relationship between city and the counties in Central Place Theory),and then found the number of nodes,the type of spatial structure,the spatial allocation of nodes with different hierarchy affecting the stability of spatial structure.According to spatial contact direction and the level of stability,UAs in China are classified into five types.Finally,it is posed as a further question that how to use hierarchical relation K=6 and K=7 in central place system to coordinate with the assessment of stability of soatial structure is brought forward.展开更多
The nonlinear dynamical behaviors of artificial neural network (ANN) and their application to science and engineering were summarized. The mechanism of two kinds of dynamical processes, i.e. weight dynamics and activa...The nonlinear dynamical behaviors of artificial neural network (ANN) and their application to science and engineering were summarized. The mechanism of two kinds of dynamical processes, i.e. weight dynamics and activation dynamics in neural networks, and the stability of computing in structural analysis and design were stated briefly. It was successfully applied to nonlinear neural network to evaluate the stability of underground stope structure in a gold mine. With the application of BP network, it is proven that the neuro-com- puting is a practical and advanced tool for solving large-scale underground rock engineering problems.展开更多
The structures of closo-hedral cluster (HAlNH)12 and endohedral complexes X@(HAlNH)12 (X = He, Ne, Ar, Kr) have been studied by using density functional theory (DFT) at the B3LYP/6-31G(d) level. The geometries, natura...The structures of closo-hedral cluster (HAlNH)12 and endohedral complexes X@(HAlNH)12 (X = He, Ne, Ar, Kr) have been studied by using density functional theory (DFT) at the B3LYP/6-31G(d) level. The geometries, natural bond orbital (NBO), vibrational frequency, energetic parameters, magnetic shielding constants and nucleus independent chemical shifts (NICS) were discussed. The potential surface of vip X shifting from the cage center to a face of six- membered ring was calculated at the same level. The exit transition state was demonstrated with IRC calculations. It is found that X@(HAlNH)12 complexes are dynamically stable, and Ne@(HAlNH)12 is more energetically favorable than the other complexes in thermodynamics.展开更多
The precipitation behavior in Inconel 718 and modified alloys has been studied by means of TEM.The structure of associated precipitation and compact morphology of γ″+γ′ were ob- tained by modifying the contents of...The precipitation behavior in Inconel 718 and modified alloys has been studied by means of TEM.The structure of associated precipitation and compact morphology of γ″+γ′ were ob- tained by modifying the contents of Al,Ti and Nb.Experimental results show that the com- pact morphology of γ″+γ′ has the best structure stability at higher temperatures.Instead of the transformation γ″→δ in alloy 718 the dissolution of strengthening phases in modified alloy leads material degradation.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
Full concentration gradient lithium-rich layered oxides are catching lots of interest as the next generation cathode for lithium-ion batteries due to their high discharge voltage,reduced voltage decay and enhanced rat...Full concentration gradient lithium-rich layered oxides are catching lots of interest as the next generation cathode for lithium-ion batteries due to their high discharge voltage,reduced voltage decay and enhanced rate performance,whereas the high lithium residues on its surface impairs the structure stability and long-term cycle performance.Herein,a facile multifunctional surface modification method is implemented to eliminate surface lithium residues of full concentration gradient lithium-rich layered oxides by a wet chemistry reaction with tetrabutyl titanate and the post-annealing process.It realizes not only a stable Li_(2)TiO_(3)coating layer with 3D diffusion channels for fast Li^(+)ions transfer,but also dopes partial Ti^(4+)ions into the sub-surface region of full concentration gradient lithium-rich layered oxides to further strengthen its crystal structure.Consequently,the modified full concentration gradient lithium-rich layered oxides exhibit improved structure stability,elevated thermal stability with decomposition temperature from 289.57℃to 321.72℃,and enhanced cycle performance(205.1 mAh g^(-1)after 150 cycles)with slowed voltage drop(1.67 mV per cycle).This work proposes a facile and integrated modification method to enhance the comprehensive performance of full concentration gradient lithium-rich layered oxides,which can facilitate its practical application for developing higher energy density lithium-ion batteries.展开更多
Tetraiodo-4,4＇-bi-l,2,4-triazole （1） was synthesized from a reaction of iodine monochloride witb 4,4＇ bi- 1,2,4-triazole （2）, which was prepared by a transamination reaction between 4-amine-1,2,4-triazole and N,...Tetraiodo-4,4＇-bi-l,2,4-triazole （1） was synthesized from a reaction of iodine monochloride witb 4,4＇ bi- 1,2,4-triazole （2）, which was prepared by a transamination reaction between 4-amine-1,2,4-triazole and N,N-dimethylformamide azine dihydrochloride （3） obtained via a Vilsmeier reaction. The title compound was extensively characterized by melting point, elemental analysis, 1R, HRMS and single crystal X-ray diffraction. The single crystal X-ray structural analysis reveals that compound 1 exhibits a stable conformation with the two triazole rings being perpendicular to minimize three-dimensional steric hindrance and stacking through aromatic zr. analysis from TGA and DSC indicates that resnectivelv. Jr packing interactions between molecules. The therma compound I decomposes at 275.40 ℃ and 338.35 C展开更多
We studied relationships between stand structure and stand stability according to thinning intensity in an afforested oriental beech stand. Various thinning intensities were applied in sample stands. We sampled eight ...We studied relationships between stand structure and stand stability according to thinning intensity in an afforested oriental beech stand. Various thinning intensities were applied in sample stands. We sampled eight plots in stands that were lightly thinned, eight plots in heavily thinned stands and eight plots in unthinned stands as a control. Height and diameter distributions of the stands were measured to assess stand structure. We quantified individual tree stability and collective stability. Heavy thinning during the first thinning operation damaged the storied structure of the stand in thicket stage and affected collective structuring ability. While most control plots had multi-storied stands, after light and heavy thinning two-storied structure became more common.Large gaps occurred in the canopy after heavy thinning. On average, nine tree collectives were formed per sampling plot in the untreated stand, seven collectives after thinning in 2008 and four collectives after thinning in 2009. Stable trees accounted for 17 % of trees in control plots, 24 % in lightly thinned plots, and 15 % in heavily thinned plots. Collective stability values were 83 % in control plots, 82 % in lightly thinned plots and 36 % in heavily thinned plots. We conclude that it is necessary to retain collective structuring capacity during thinning operations for sustaining stand stability.展开更多
A new complex Cu2（o-C6H5COC6H5COO）4（C10H8N2）2（H2O）2 with 2-benzoylben- zoic acid and 2,2′-bipyridine as ligands has been synthesized in mixed methanol and water solvent. Crystal data are as follows： monoclinic...A new complex Cu2（o-C6H5COC6H5COO）4（C10H8N2）2（H2O）2 with 2-benzoylben- zoic acid and 2,2′-bipyridine as ligands has been synthesized in mixed methanol and water solvent. Crystal data are as follows： monoclinic, space group Co, a = 14.0133（14）, b = 16.0409（16）, c = 30.372（3） A, β = 100.8950（10）°, V = 6704.1（12） A3, Dc = 1.364 g/cm3, Z = 8,μ（MoKa） = 0.704 mml, F（000） = 2840, the final R= 0.0552 and wR = 0.1431. In the crystal structure, the whole molecule consists of two copper ions, four 2-benzoylbenzoic acid molecules, two 2,2′-bipyridine molecules and two water molecules. Each central copper ion is coordinated with two nitrogen atoms from one 2,2′-bipyridine molecule and three oxygen atoms from two 2-benzoylbenzoic acids and one water molecule, respectively, giving a distorted tetragonal pyramidal geometry. Thermal stability properties of the complex were investigated.展开更多
Using first-principles pseudo-potential plane wave method, the energetics, geometrical and electronic structures of three Al13I cluster isomers were calculated. The calculation results of the binding energy indicate A...Using first-principles pseudo-potential plane wave method, the energetics, geometrical and electronic structures of three Al13I cluster isomers were calculated. The calculation results of the binding energy indicate Al13I cluster is more stable than Al13 cluster although its electrons are not a magic number as in Alia cluster, and among Al13I cluster isomers the ＂Bridge＂ structure is the most stable, the second is the ＂Ontop＂ structure, and the worst is the ＂Hollow＂ structure. By analyzing the geometrical structures of Al13I cluster isomers, it is found that after I atom and Al13 cluster combine the geometrical structures of Al13 moieties are changed besides Al13I Hollow cluster, in which the Alia moiety is still a regular icosahedron. For Al13I Ontop cluster, the Al13 moiety has a shrinking trend to I, whereas in Al13I Bridge cluster it is distorted. Mulliken population analysis shows for the interaction of electrons between Al-I atoms in Al13I cluster not only there exists an ionic bonding but there is a covalent bonding. Part of electrons in the Alia cluster transfer to I as Al13 cluster and I atom combine. The order of the strength of covalent bonding between Al13 moiety and I in Al13I cluster isomers is Al13IBridge〉Al13IHollow〉Al13I Ontop. Further analysis of electric structures of Al13 and Al13I clusters indicates a higher stability of Al13I cluster than Al13 cluster can be attributed to the s-p hybridization of 3s and 3p electrons of Al in Al13 moiety induced by 1 doped, which leads to fewer electrons N（EF） at EF in Al13I and a larger energy gap △EH-L between HOMO and LUMO levels in Al13I cluster. The distinguish of structural stability of Al13I cluster isomers mainly originates from their different magnitudes .in decrease of N（EF） and increase of △EH-L relative to Al13 cluster. The fewest N（EF） and the largest △EH-L are responsible for the high stability of Al13I Bridge cluster.展开更多
The submerged structure is basically a large three-dimensional structure of few statically redundant members. The structure is subjected to vertical dead and live loads in addition to the wave forces. An analysis of d...The submerged structure is basically a large three-dimensional structure of few statically redundant members. The structure is subjected to vertical dead and live loads in addition to the wave forces. An analysis of dynamic stability of the submerged structure without damping has been made by J. Thomas and Abbas (1980). In this paper the analyses of dynamic stability of the sumberged structure with damping are conducted. The case structure with damping is more complicated 'than the case without it. According to the principle of perturbation, a new model for dynamic stability calculation in consideration of damping effect is developed. In this paper, the formulas are deduced, the computational program is compiled, the practical examples are analysed, and this problem is solved very satisfactorily. The computational results show that the shape and value of the regions of dynamic instability can be changed significantly by damping. So only by considering damping can the property of dynamic stability of the submerged structure be reflected correctly.展开更多
The effect of Ga_2O_3 on the structure and properties of calcium aluminate glasses fabricated by vacuum melting process was investigated by Raman spectrum, differential scanning calorimeter（DSC）, and infrared spectr...The effect of Ga_2O_3 on the structure and properties of calcium aluminate glasses fabricated by vacuum melting process was investigated by Raman spectrum, differential scanning calorimeter（DSC）, and infrared spectrum methods. The results show that calcium aluminate glass network only consists of [AlO_4] tetrahedral units. With the gradual addition of Ga_2O_3, the quantity of [GaO_4] tetrahedral units increases. Substitution of Ga_2O_3 for Al_2O_3 results in a decrease in Tg, Tx, and Tp, and an increase in the thermal stable index ΔT. Similarly, the absorption band around 3.0 μm obviously reduces and the transparency in 4.0-6.0 μm rapidly increases with increasing Ga_2O_3 content. However, the chemical stability of calcium aluminate glasses decreases if Ga_2O_3 is introduced due to the increasing of [GaO_4] units in the glass network.展开更多
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financial support provided by the National Natural Science Foundation of China(52271201)the Science and Technology Department of Sichuan Province(2025NSFTD0005,2022YFG0100,2022ZYD0045)。
文摘LiNixCoyMn_(2)O_(2)(NCM,x≥0.8,x+y+z=1)cathodes have attracted much attention due to their high specific capacity and low cost.However,severe anisotropic volume changes and oxygen evolution induced capacity decay and insecurity have hindered their commercial application at scale.In order to overcome these challenges,a kind of tantalum(Ta)doped nickel-rich cathode with reduced size and significantly increased number of primary particles is prepared by combining mechanical fusion with high temperature co-calcination.The elaborately designed micro-morphology of small and uniform primary particles effectively eliminates the local strain accumulation caused by the random orientation of primary particles.Moreover,the uniform distribution of small primary particles stabilizes the spherical secondary particles,thus effectively inhibiting the formation and extension of microcracks.In addition,the formed strong Ta-O bonds restrain the release of lattice oxygen,which greatly increases the structural stability and safety of NCM materials.Therefore,the cathode material with the designed primary particle morphology shows superior electrochemical performance.The 1 mol%Ta-modified cathode(defined as1%Ta-NCM)shows a capacity retention of 97.5%after 200 cycles at 1 C and a rate performance of 137.3 mAh g^(-1)at 5 C.This work presents promising approach to improve the structural stability and safety of nickel-rich NCM.
文摘Fiber is highly escapable in conventional slickwater,making it difficult to form fiber-proppant agglomerate with proppant and exhibit limited effectiveness.To solve these problems,a novel structure stabilizer(SS)is developed.Through microscopic structural observations and performance evaluations in indoor experiments,the mechanism of proppant placement under the action of the SS and the effects of the SS on proppant placement dimensions and fracture conductivity were elucidated.The SS facilitates the formation of robust fiber-proppant agglomerates by polymer,fiber,and quartz sand.Compared to bare proppants,these agglomerates exhibit reduced density,increased volume,and enlarged contact area with the fluid during settlement,leading to heightened buoyancy and drag forces,ultimately resulting in slower settling velocities and enhanced transportability into deeper regions of the fracture.Co-injecting the fiber and the SS alongside the proppant into the reservoir effectively reduces the fiber escape rate,increases the proppant volume in the slickwater,and boosts the proppant placement height,conveyance distance and fracture conductivity,while also decreasing the proppant backflow.Experimental results indicate an optimal SS mass fraction of 0.3%.The application of this SS in over 80 wells targeting tight gas,shale oil,and shale gas reservoirs has substantiated its strong adaptability and general suitability for meeting the production enhancement,cost reduction,and sand control requirements of such wells.
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 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Project (HEUCFR1128) supported by the Fundamental Research Funds for the Central Universities,ChinaProject (2010AA4BE031)supported by the Key Project of Science and Technology of Harbin City,China+1 种基金Projects (20100471015,20100471046) supported by the China Postdoctoral Science FoundationProject (LBH-Z09217) supported by the Heilongjiang Postdoctorial Fund,China
文摘With the aim to further improve the mechanical properties of Mg-A1-RE-based alloy, Mg-3.0Al-1.8Ce-0.3Y-0.2Mn alloy was prepared by high-pressure die-casting technique. The microstructure, thermal stability of intermetallic phases and mechanical properties were investigated. The results show that the alloy is composed of fine primary a-Mg dendrites and eutectic in the interdendritic regions. The intermetallic phases in eutectic are Aln（Ce,Y）3 and A12（Ce,Y） with the former being the dominant one. The thermal stability of Al11（ce,Y）3 is conditioned. It is basically stable at temperature up to 200℃ within 800 h, while most of the Al11（Ce,Y）3 intermetallics transform to A12（Ce,Y） at higher temperature of 450 ℃ for 800 h. The alloy exhibits remarkably improved strength both at room temperature and 200℃, which is mainly attributed to the reinforcement of dendrite boundaries with Alll（Ce,Y）3 intermetallics, small dendritic arm spacing effect as well as the solid solution strengthening with Y element.
基金financially supported by the Beijing Natural Science Foundation(Grant No.L182022)the NSAF(Grant No.U1930113)+1 种基金the National Natural Science Foundation of China(52072036)the Guangdong Key Laboratory of Battery Safety(2019B121203008),China。
文摘Lithium ion power batteries have undoubtedly become one of the most promising rechargeable batteries at present;nonetheless,they still suffer from the challenges such as requirement of even higher energy density and capacity retention.Nickel-rich layer oxides(Ni≥0.8)become ideal cathode materials to achieve the high specific capacity.Integration of optimization of synthesis process and modification of crystal structure to suppress the capacity fading can obviously improve the performance of the lithium ion batteries.This review presents the recent modification strategies of the nickel-rich layered oxide materials.Unlike in previous reviews and related papers,the specific mechanism about each type of the modification strategies is specially discussed in detail,which is mainly about inhibiting the anisotropic lattice strain and adjusting the cation mixing degree to maintain crystal structure.Based on the recent progress,the prospects and challenges of the modified nickel-rich layer cathodes to upgrade the property of lithium ion batteries are also comprehensively analyzed,and the potential applications in the field of plug-in hybrid vehicles and electric vehicles are further discussed.
基金Under the auspices of the National Natural Science Foundation of China(No.40335049,40471059)
文摘This paper brings forward the concept of stability of the spatial structure of urban agglomeration(UA)based on Central Place Theory by introducing centrality index and fractal theory.Before assessment,K=4 is selected as parameter to calculate centrality index and fractal dimension(K represents the quantitive relationship between city and the counties in Central Place Theory),and then found the number of nodes,the type of spatial structure,the spatial allocation of nodes with different hierarchy affecting the stability of spatial structure.According to spatial contact direction and the level of stability,UAs in China are classified into five types.Finally,it is posed as a further question that how to use hierarchical relation K=6 and K=7 in central place system to coordinate with the assessment of stability of soatial structure is brought forward.
基金This work was financially supported by the Key Project for National Science of "9.5" (Reward Ⅱ for National Science and Technol
文摘The nonlinear dynamical behaviors of artificial neural network (ANN) and their application to science and engineering were summarized. The mechanism of two kinds of dynamical processes, i.e. weight dynamics and activation dynamics in neural networks, and the stability of computing in structural analysis and design were stated briefly. It was successfully applied to nonlinear neural network to evaluate the stability of underground stope structure in a gold mine. With the application of BP network, it is proven that the neuro-com- puting is a practical and advanced tool for solving large-scale underground rock engineering problems.
基金This work was supported by the National Natural Science Foundation of China (No. 20341005), Natural Science Foundation of Shanxi Province (No. 20011015) and the Foundation for University Key Teachers by the Ministry of Education
文摘The structures of closo-hedral cluster (HAlNH)12 and endohedral complexes X@(HAlNH)12 (X = He, Ne, Ar, Kr) have been studied by using density functional theory (DFT) at the B3LYP/6-31G(d) level. The geometries, natural bond orbital (NBO), vibrational frequency, energetic parameters, magnetic shielding constants and nucleus independent chemical shifts (NICS) were discussed. The potential surface of vip X shifting from the cage center to a face of six- membered ring was calculated at the same level. The exit transition state was demonstrated with IRC calculations. It is found that X@(HAlNH)12 complexes are dynamically stable, and Ne@(HAlNH)12 is more energetically favorable than the other complexes in thermodynamics.
文摘The precipitation behavior in Inconel 718 and modified alloys has been studied by means of TEM.The structure of associated precipitation and compact morphology of γ″+γ′ were ob- tained by modifying the contents of Al,Ti and Nb.Experimental results show that the com- pact morphology of γ″+γ′ has the best structure stability at higher temperatures.Instead of the transformation γ″→δ in alloy 718 the dissolution of strengthening phases in modified alloy leads material degradation.
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financially supported by the Natural Science Foundation of Shandong Province(ZR2022QB166,ZR2020KE032)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA22010600)+3 种基金the Youth Innovation Promotion Association of CAS(2021210)the Foundation of Qingdao Postdoctoral Application Program(Y63302190F)the Natural Science Foundation of Qingdao Institute ofBioenergy and Bioprocess Technology(QIBEBT SZ202101)support from the Max Planck-POSTECH-Hsinchu Center for Complex Phase Materials
文摘Full concentration gradient lithium-rich layered oxides are catching lots of interest as the next generation cathode for lithium-ion batteries due to their high discharge voltage,reduced voltage decay and enhanced rate performance,whereas the high lithium residues on its surface impairs the structure stability and long-term cycle performance.Herein,a facile multifunctional surface modification method is implemented to eliminate surface lithium residues of full concentration gradient lithium-rich layered oxides by a wet chemistry reaction with tetrabutyl titanate and the post-annealing process.It realizes not only a stable Li_(2)TiO_(3)coating layer with 3D diffusion channels for fast Li^(+)ions transfer,but also dopes partial Ti^(4+)ions into the sub-surface region of full concentration gradient lithium-rich layered oxides to further strengthen its crystal structure.Consequently,the modified full concentration gradient lithium-rich layered oxides exhibit improved structure stability,elevated thermal stability with decomposition temperature from 289.57℃to 321.72℃,and enhanced cycle performance(205.1 mAh g^(-1)after 150 cycles)with slowed voltage drop(1.67 mV per cycle).This work proposes a facile and integrated modification method to enhance the comprehensive performance of full concentration gradient lithium-rich layered oxides,which can facilitate its practical application for developing higher energy density lithium-ion batteries.
基金supported by the National Key Projects(No.00402040103)Youth Innovation Research Team of Sichuan for Carbon Nanomaterials(No.2011JTD0017)
文摘Tetraiodo-4,4＇-bi-l,2,4-triazole （1） was synthesized from a reaction of iodine monochloride witb 4,4＇ bi- 1,2,4-triazole （2）, which was prepared by a transamination reaction between 4-amine-1,2,4-triazole and N,N-dimethylformamide azine dihydrochloride （3） obtained via a Vilsmeier reaction. The title compound was extensively characterized by melting point, elemental analysis, 1R, HRMS and single crystal X-ray diffraction. The single crystal X-ray structural analysis reveals that compound 1 exhibits a stable conformation with the two triazole rings being perpendicular to minimize three-dimensional steric hindrance and stacking through aromatic zr. analysis from TGA and DSC indicates that resnectivelv. Jr packing interactions between molecules. The therma compound I decomposes at 275.40 ℃ and 338.35 C
基金supported by Karadeniz Technical University Research Fund,Project number 2010.113.001.11
文摘We studied relationships between stand structure and stand stability according to thinning intensity in an afforested oriental beech stand. Various thinning intensities were applied in sample stands. We sampled eight plots in stands that were lightly thinned, eight plots in heavily thinned stands and eight plots in unthinned stands as a control. Height and diameter distributions of the stands were measured to assess stand structure. We quantified individual tree stability and collective stability. Heavy thinning during the first thinning operation damaged the storied structure of the stand in thicket stage and affected collective structuring ability. While most control plots had multi-storied stands, after light and heavy thinning two-storied structure became more common.Large gaps occurred in the canopy after heavy thinning. On average, nine tree collectives were formed per sampling plot in the untreated stand, seven collectives after thinning in 2008 and four collectives after thinning in 2009. Stable trees accounted for 17 % of trees in control plots, 24 % in lightly thinned plots, and 15 % in heavily thinned plots. Collective stability values were 83 % in control plots, 82 % in lightly thinned plots and 36 % in heavily thinned plots. We conclude that it is necessary to retain collective structuring capacity during thinning operations for sustaining stand stability.
基金Supported by the Natural Science Foundation of Hunan Province (No. 11JJ9006)Key Project of Science and Technology Plan of Hunan Province (2012FJ2002)+1 种基金Science and Technology Plan of Hunan Province (2012GK3031, 2012WK3029)the Construct Program of Key Discipline in Hunan Province
文摘A new complex Cu2（o-C6H5COC6H5COO）4（C10H8N2）2（H2O）2 with 2-benzoylben- zoic acid and 2,2′-bipyridine as ligands has been synthesized in mixed methanol and water solvent. Crystal data are as follows： monoclinic, space group Co, a = 14.0133（14）, b = 16.0409（16）, c = 30.372（3） A, β = 100.8950（10）°, V = 6704.1（12） A3, Dc = 1.364 g/cm3, Z = 8,μ（MoKa） = 0.704 mml, F（000） = 2840, the final R= 0.0552 and wR = 0.1431. In the crystal structure, the whole molecule consists of two copper ions, four 2-benzoylbenzoic acid molecules, two 2,2′-bipyridine molecules and two water molecules. Each central copper ion is coordinated with two nitrogen atoms from one 2,2′-bipyridine molecule and three oxygen atoms from two 2-benzoylbenzoic acids and one water molecule, respectively, giving a distorted tetragonal pyramidal geometry. Thermal stability properties of the complex were investigated.
基金This work was supported by the Science & Technology Major Programs of Ministry of Education of China (No. 101139)
文摘Using first-principles pseudo-potential plane wave method, the energetics, geometrical and electronic structures of three Al13I cluster isomers were calculated. The calculation results of the binding energy indicate Al13I cluster is more stable than Al13 cluster although its electrons are not a magic number as in Alia cluster, and among Al13I cluster isomers the ＂Bridge＂ structure is the most stable, the second is the ＂Ontop＂ structure, and the worst is the ＂Hollow＂ structure. By analyzing the geometrical structures of Al13I cluster isomers, it is found that after I atom and Al13 cluster combine the geometrical structures of Al13 moieties are changed besides Al13I Hollow cluster, in which the Alia moiety is still a regular icosahedron. For Al13I Ontop cluster, the Al13 moiety has a shrinking trend to I, whereas in Al13I Bridge cluster it is distorted. Mulliken population analysis shows for the interaction of electrons between Al-I atoms in Al13I cluster not only there exists an ionic bonding but there is a covalent bonding. Part of electrons in the Alia cluster transfer to I as Al13 cluster and I atom combine. The order of the strength of covalent bonding between Al13 moiety and I in Al13I cluster isomers is Al13IBridge〉Al13IHollow〉Al13I Ontop. Further analysis of electric structures of Al13 and Al13I clusters indicates a higher stability of Al13I cluster than Al13 cluster can be attributed to the s-p hybridization of 3s and 3p electrons of Al in Al13 moiety induced by 1 doped, which leads to fewer electrons N（EF） at EF in Al13I and a larger energy gap △EH-L between HOMO and LUMO levels in Al13I cluster. The distinguish of structural stability of Al13I cluster isomers mainly originates from their different magnitudes .in decrease of N（EF） and increase of △EH-L relative to Al13 cluster. The fewest N（EF） and the largest △EH-L are responsible for the high stability of Al13I Bridge cluster.
文摘The submerged structure is basically a large three-dimensional structure of few statically redundant members. The structure is subjected to vertical dead and live loads in addition to the wave forces. An analysis of dynamic stability of the submerged structure without damping has been made by J. Thomas and Abbas (1980). In this paper the analyses of dynamic stability of the sumberged structure with damping are conducted. The case structure with damping is more complicated 'than the case without it. According to the principle of perturbation, a new model for dynamic stability calculation in consideration of damping effect is developed. In this paper, the formulas are deduced, the computational program is compiled, the practical examples are analysed, and this problem is solved very satisfactorily. The computational results show that the shape and value of the regions of dynamic instability can be changed significantly by damping. So only by considering damping can the property of dynamic stability of the submerged structure be reflected correctly.
基金Funded by the National Natural Science Foundation of China(No.60808024)
文摘The effect of Ga_2O_3 on the structure and properties of calcium aluminate glasses fabricated by vacuum melting process was investigated by Raman spectrum, differential scanning calorimeter（DSC）, and infrared spectrum methods. The results show that calcium aluminate glass network only consists of [AlO_4] tetrahedral units. With the gradual addition of Ga_2O_3, the quantity of [GaO_4] tetrahedral units increases. Substitution of Ga_2O_3 for Al_2O_3 results in a decrease in Tg, Tx, and Tp, and an increase in the thermal stable index ΔT. Similarly, the absorption band around 3.0 μm obviously reduces and the transparency in 4.0-6.0 μm rapidly increases with increasing Ga_2O_3 content. However, the chemical stability of calcium aluminate glasses decreases if Ga_2O_3 is introduced due to the increasing of [GaO_4] units in the glass network.
