AZ31 magnesium alloy was used as the object of study to fabricate an alloy with the bimodal grain structure using singlepass hot rolling,and to explore how this structure enhances the strength and plasticity of the al...AZ31 magnesium alloy was used as the object of study to fabricate an alloy with the bimodal grain structure using singlepass hot rolling,and to explore how this structure enhances the strength and plasticity of the alloy.The results show that the formation of the bimodal grain structure is more pronounced at rolling temperatures ranging from 350°C to 450°C,especially under conditions of large reduction(≥40%).The optimized proportion and distribution of the bimodal grain structure play a pivotal role in simultaneously enhancing the strength and ductility of the alloy,significantly impacting the mechanical properties.The rolled sheet with the bimodal grain structure achieves an ultimate tensile strength of 258.3 MPa and an elongation of 17.1%under a rolling reduction of 40%with the rolling rate of 75 m/min and rolling temperature of 400°C.Adjusting rolling parameters,including temperature,reduction ratio and rolling rate,is crucial for optimizing the bimodal grain structure,thereby achieving a balance between plasticity improvement and high strength maintenance.展开更多
With the rapid development of flexible equipment,high-energy/-power requirements have been proposed for energy storage devices.Nevertheless,the poor conductivities of metallic oxides and their low levels of transmissi...With the rapid development of flexible equipment,high-energy/-power requirements have been proposed for energy storage devices.Nevertheless,the poor conductivities of metallic oxides and their low levels of transmission of electrons/ions hinder their widespread application.Here,a sandwich-structured Co_(3)O_(4)-Fe_(3)O_(4)(CFO) composite with binder-free was synthesized on a carbon cloth substrate via co-precipitation and partial ion exchange.The appropriate substitution of Co_(3)O_(4)with Fe_(3)O_(4)is favorable in promoting the rapid transfer of electrolyte ions and alleviating changes in volume during the electrochemical studies.When the duration of the substitution reaction is 20 min,the obtained electrode delivers a maximum specific capacitance of 1196.2 Fg^(-1)at a current density of 1 A g^(-1)and a superior capacity retention of~71%when the current density varies from 1to 30 Ag^(-1).Furthermore,the fabricated CFO//activated carbon flexible all-solid-state supercapacitor exhibits arespective maximum energy and power density of 68.7Wh kg^(-1)and 16,000 W kg^(-1)and excellent flexibility.It also displays a specific capacity retention of 81.3%under four continuous bending states at a current density of 6A g^(-1)over 10,000 cycles.These remarkable electrochemical char ac teristics suggest that the sandwich-structured CFO composite displays considerable potential for application in flexible high-energy/-power supercapacitors.展开更多
Sodium-ion batteries have emerged as promising candidates for next-generation large-scale energy storage systems due to the abundance of sodium resources,low solvation energy,and cost-effectiveness.Among the available...Sodium-ion batteries have emerged as promising candidates for next-generation large-scale energy storage systems due to the abundance of sodium resources,low solvation energy,and cost-effectiveness.Among the available cathode materials,vanadium-based sodium phosphate cathodes are particularly notable for their high operating voltage,excellent thermal stability,and superior cycling performance.However,these materials face significant challenges,including sluggish reaction kinetics,the toxicity of vanadium,and poor electronic conductivity.To overcome these limitations and enhance electrochemical performance,various strategies have been explored.These include morphology regulation via diverse synthesis routes and electronic structure optimization through metal doping,which effectively improve the diffusion of Na+and electrons in vanadium-based phosphate cathodes.This review provides a comprehensive overview of the challenges associated with V-based polyanion cathodes and examines the role of morphology and electronic structure design in enhancing performance.Key vanadium-based phosphate frameworks,such as orthophosphates(Na_(3)V_(2)(PO_(4))_(3)),pyrophosphates(NaVP_(2)O_(7),Na_(2)(VO)P_(2)O_(7),Na_(7)V_(3)(P_(2)O_(7))_(4)),and mixed phosphates(Na_(7)V_(4)(P_(2)O_(7))_(4)PO_(4)),are discussed in detail,highlighting recent advances and insights into their structure-property relationships.The design of cathode material morphology offers an effective approach to optimizing material structures,compositions,porosity,and ion/electron diffusion pathways.Simultaneously,electronic structure tuning through element doping allows for the regulation of band structures,electron distribution,diffusion barriers,and the intrinsic conductivity of phosphate compounds.Addressing the challenges associated with vanadium-based sodium phosphate cathode materials,this study proposes feasible solutions and outlines future research directions toward advancement of high-performance vanadium-based polyanion cathodes.展开更多
Transition metal carbonates(TMCs)hold great potential as high-performance electrodes for alkali metal-ion batteries,owing to multiple-ion storage mechanisms involving conversion process and electrocatalytic reaction.H...Transition metal carbonates(TMCs)hold great potential as high-performance electrodes for alkali metal-ion batteries,owing to multiple-ion storage mechanisms involving conversion process and electrocatalytic reaction.However,they still suffer from inferior electronic conductivity and volume variation during delithiation/lithiation.Heterostructure and heteroatoms doping offer immense promise in enhancing reaction kinetics and structural integrity,which unfortunately have not been achieved in TMCs.Herein,a unique TMCs heterostructure with Ni-doped MnCO_(3)as“core”and Mn-doped NiCO_(3)as“shell”,which is wrapped by graphene(NM@MN/RGO),is achieved by cations differentiation strategy.The formation process for core-shell NM@MN consists of epitaxial growth of NiCO_(3)from MnCO_(3)and synchronously mutual doping,owing to the similar crystal structures but different solubility product constant/formation energy of MnCO_(3)and NiCO_(3).In-situ electrochemical impedance spectroscopy,galvanostatic intermittent titration technique,differential capacity versus voltage plots,theoretical calculation and kinetic analysis reveal the superior electrochemical activity of the NM@MN/RGO to MnCO_(3)/RGO.The NM@MN/RGO shows excellent lithium storage properties(1013.4 mAh·g^(-1)at 0.1 A·g^(-1)and 760 mAh·g^(-1)after 1000 cycles at 2 A·g^(-1))and potassium storage properties(capacity decay rate of 0.114 mAh·g^(-1)per cycle).This work proposes an efficient cation differentiation strategy for constructing advanced TMC electrodes.展开更多
Solid-state polymer electrolytes are crucial for advancing solid-state lithium-metal batteries owing to their flexibility,excellent manufacturability,and strong interfacial compatibility.However,their widespread appli...Solid-state polymer electrolytes are crucial for advancing solid-state lithium-metal batteries owing to their flexibility,excellent manufacturability,and strong interfacial compatibility.However,their widespread applications are hindered by low ionic conductivity at room temperature and lithium dendrite growth.Herein,we report a novel solid-state composite membrane electrolyte design that combines the vertically aligned channel structure and copolymer with a radial gradient composition.Within the vertically aligned channels,the composition of poly(vinyl ethylene carbonate-co-poly(ethylene glycol)diacrylate)(P(VEC-PEGDA)varies in a gradient along the radial direction:from the center to the wall of vertically aligned channels,the proportion of vinyl ethylene carbonate(VEC)in the copolymer decreases,while the proportion of poly(ethylene glycol)diacrylate(PEGDA)increases accordingly.It can be functionally divided into a mechanical-reinforcement layer and a fast-ion-conducting layer.The resulting solid-state composite membrane electrolyte achieves a high critical current density of 1.2 mA cm^(-2)and high ionic conductivity of 2.03 mS cm^(-1)at room temperature.Employing this composite membrane electrolyte,a Li//Li symmetric cell exhibits stable cycling for over 1850 h at 0.2 m A cm^(-2)/0.2 m A h cm^(-2),and a Li//LiFePO4(LFP)battery maintains 77.3% capacity retention at 2 C after 300 cycles.Our work provides insight into the rational design of safer and more efficient solidstate batteries through electrolyte structural engineering.展开更多
Six new lanthanide complexes:[Ln(3,4-DEOBA)3(4,4'-DM-2,2'-bipy)]2·2C_(2)H_(5)OH,[Ln=Dy(1),Eu(2),Tb(3),Sm(4),Ho(5),Gd(6);3,4-DEOBA-=3,4-diethoxybenzoate,4,4'-DM-2,2'-bipy=4,4'-dimethyl-2,2'...Six new lanthanide complexes:[Ln(3,4-DEOBA)3(4,4'-DM-2,2'-bipy)]2·2C_(2)H_(5)OH,[Ln=Dy(1),Eu(2),Tb(3),Sm(4),Ho(5),Gd(6);3,4-DEOBA-=3,4-diethoxybenzoate,4,4'-DM-2,2'-bipy=4,4'-dimethyl-2,2'-bipyridine]were successfully synthesized by the volatilization of the solution at room temperature.The crystal structures of six complexes were determined by single-crystal X-ray diffraction technology.The results showed that the complexes all have a binuclear structure,and the structures contain free ethanol molecules.Moreover,the coordination number of the central metal of each structural unit is eight.Adjacent structural units interact with each other through hydrogen bonds and further expand to form 1D chain-like and 2D planar structures.After conducting a systematic study on the luminescence properties of complexes 1-4,their emission and excitation spectra were obtained.Experimental results indicated that the fluorescence lifetimes of complexes 2 and 3 were 0.807 and 0.845 ms,respectively.The emission spectral data of complexes 1-4 were imported into the CIE chromaticity coordinate system,and their corre sponding luminescent regions cover the yellow light,red light,green light,and orange-red light bands,respectively.Within the temperature range of 299.15-1300 K,the thermal decomposition processes of the six complexes were comprehensively analyzed by using TG-DSC/FTIR/MS technology.The hypothesis of the gradual loss of ligand groups during the decomposition process was verified by detecting the escaped gas,3D infrared spectroscopy,and ion fragment information detected by mass spectrometry.The specific decomposition path is as follows:firstly,free ethanol molecules and neutral ligands are removed,and finally,acidic ligands are released;the final product is the corresponding metal oxide.CCDC:2430420,1;2430422,2;2430419,3;2430424,4;2430421,5;2430423,6.展开更多
To elucidate the effect of calcite-regulated activated carbon(AC)structure on low-temperature denitrification performance of SCR catalysts,this work prepared a series of Mn-Ce/De-AC-xCaCO_(3)(x is the calcite content ...To elucidate the effect of calcite-regulated activated carbon(AC)structure on low-temperature denitrification performance of SCR catalysts,this work prepared a series of Mn-Ce/De-AC-xCaCO_(3)(x is the calcite content in coal)catalysts were prepared by the incipient wetness impregnation method,followed by acid washing to remove calcium-containing minerals.Comprehensive characterization and low-temperature denitrification tests revealed that calcite-induced structural modulation of coal-derived AC significantly enhances catalytic activity.Specifically,NO conversion increased from 88.3%of Mn-Ce/De-AC to 91.7%of Mn-Ce/De-AC-1CaCO_(3)(210℃).The improved SCR denitrification activity results from the enhancement of physicochemical properties including higher Mn^(4+)content and Ce^(4+)/Ce^(3+)ratio,an abundance of chemisorbed oxygen and acidic sites,which could strengthen the SCR reaction pathways(richer NH_(3)activated species and bidentate nitrate active species).Therefore,NO removal is enhanced.展开更多
Alkali-free SiO_(2)-Al_(2)O_(3)-CaO-MgO with different SiO_(2)/Al_(2)O_(3)mass ratios was prepared by conventional melt quenching method.The glass network structure,thermodynamic properties and elastic modulus changes...Alkali-free SiO_(2)-Al_(2)O_(3)-CaO-MgO with different SiO_(2)/Al_(2)O_(3)mass ratios was prepared by conventional melt quenching method.The glass network structure,thermodynamic properties and elastic modulus changes with SiO_(2)and Al_(2)O_(3)ratios were investigated using various techniques.It is found that when SiO_(2)is replaced by Al_(2)O_(3),the Q^(4) to Q^(3) transition of silicon-oxygen network decreases while the aluminum-oxygen network increases,which result in the transformation of Si-O-Si bonds to Si-O-Al bonds and an increase in glass network connectivity even though the intermolecular bond strength decreases.The glass transition temperature(T_(g))increases continuously,while the thermal expansion coefficient increases and high-temperature viscosity first decreases and then increases.Meanwhile,the elastic modulus values increase from 93 to 102 GPa.This indicates that the elastic modulus is mainly affected by packing factor and dissociation energy,and elements with higher packing factors and dissociation energies supplant those with lower values,resulting in increased rigidity within the glass.展开更多
To investigate the pore structure of graphene oxide modified polymer cement mortar(GOPM)under salt-freeze-thaw(SFT)coupling effects and its impact on deterioration,this study modifies polymer cement mortar(EMCM)with g...To investigate the pore structure of graphene oxide modified polymer cement mortar(GOPM)under salt-freeze-thaw(SFT)coupling effects and its impact on deterioration,this study modifies polymer cement mortar(EMCM)with graphene oxide(GO).The micro-pore structure of GOPM is characterized using LF-NMR and SEM.Fractal theory is applied to calculate the fractal dimension of pore volume,and the deterioration patterns are analyzed based on the evolution characteristics of capillary pores.The experimental results indicate that,after 25 salt-freeze-thaw cycles(SFTc),SO2-4 ions penetrate the matrix,generating corrosion products that fill existing pores and enhance the compactness of the specimen.As the number of cycles increases,the ongoing formation and expansion of corrosion products within the matrix,combined with persistent freezing forces,and result in the degradation of the pore structure.Therefore,the mass loss rate(MLR)of the specimens shows a trend of first decreasing and then increasing,while the relative dynamic elastic modulus(RDEM)initially increases and then decreases.Compared to the PC group specimens,the G3PM group specimens show a 28.71% reduction in MLR and a 31.42% increase in RDEM after 150 SFTc.The fractal dimensions of the transition pores,capillary pores,and macropores in the G3PM specimens first increase and then decrease as the number of SFTc increases.Among them,the capillary pores show the highest correlation with MLR and RDEM,with correlation coefficients of 0.97438 and 0.98555,respectively.展开更多
Tilted metasurface nanostructures,with excellent physical properties and enormous application potential,pose an urgent need for manufacturing methods.Here,electric-field-driven generative-nanoimprinting technique is p...Tilted metasurface nanostructures,with excellent physical properties and enormous application potential,pose an urgent need for manufacturing methods.Here,electric-field-driven generative-nanoimprinting technique is proposed.The electric field applied between the template and the substrate drives the contact,tilting,filling,and holding processes.By accurately controlling the introduced included angle between the flexible template and the substrate,tilted nanostructures with a controllable angle are imprinted onto the substrate,although they are vertical on the template.By flexibly adjusting the electric field intensity and the included angle,large-area uniform-tilted,gradient-tilted,and high-angle-tilted nanostructures are fabricated.In contrast to traditional replication,the morphology of the nanoimprinting structure is extended to customized control.This work provides a cost-effective,efficient,and versatile technology for the fabrication of various large-area tilted metasurface structures.As an illustration,a tilted nanograting with a high coupling efficiency is fabricated and integrated into augmented reality displays,demonstrating superior imaging quality.展开更多
AIM:To investigate the effects of shortening the duration of silicone oil tamponade on retinal structure and function in patients undergoing silicone oil removal(SOR)after surgery for primary rhegmatogenous retinal de...AIM:To investigate the effects of shortening the duration of silicone oil tamponade on retinal structure and function in patients undergoing silicone oil removal(SOR)after surgery for primary rhegmatogenous retinal detachment(RRD).METHODS:A total of 58 eligible patients were enrolled and randomly assigned to two groups based on tamponade duration:the short-term group(30-45d)and the conventional group(≥90d).Comprehensive evaluations were performed before and after SOR,including slitlamp examination,best-corrected visual acuity(BCVA)measurement,intraocular pressure(IOP)testing,optical coherence tomography(OCT),optical coherence tomography angiography(OCTA),microperimetry,electroretinography(ERG),and visual evoked potential(VEP)assessment.RESULTS:A total of 33 patients(23 males and 10 females;33 eyes)were enrolled in the short-term SO tamponade group with mean age of 52.45±9.35y,and 25 patients(15 males and 10 females;25 eyes)were enrolled in the conventional SO tamponade group with mean age of 50.80±12.06y.Compared with the conventional group,the short-term silicone oil tamponade group had a significantly lower incidence of silicone oil emulsification and cataract progression,with no significant difference in retinal reattachment success rate.Structurally,short-term tamponade was associated with increased thickness of the retinal ganglion cell layer(RGCL)in the nasal and superior macular regions and improved recovery of superficial retinal vascular density in these areas.Functionally,the shortterm group showed better BCVA and retinal sensitivity both before and 1mo after SOR;additionally,the P100 amplitude in VEP tests was significantly increased in this group.CONCLUSION:Shortening the duration of silicone oil tamponade effectively reduces damage to retinal structure and function without compromising the success rate of retinal reattachment in patients with primary RRD.展开更多
Transition-metal nitrides exhibit wide potential windows and good electrochemical performance, but usually experience imbalanced practical applications in the energy storage field due to aggregation, poor circulation ...Transition-metal nitrides exhibit wide potential windows and good electrochemical performance, but usually experience imbalanced practical applications in the energy storage field due to aggregation, poor circulation stability, and complicated syntheses. In this study, a novel and simple multiphase polymeric strategy was developed to fabricate hybrid vanadium nitride/carbon(VN/C) membranes for supercapacitor negative electrodes, in which VN nanoparticles were uniformly distributed in the hierarchical porous carbon 3D networks. The supercapacitor negative electrode based on VN/C membranes exhibited a high specific capacitance of 392.0 F g^(-1) at 0.5 A g^(-1) and an excellent rate capability with capacitance retention of 50.5% at 30 A g^(-1). For the asymmetric device fabricated using Ni(OH)_2//VN/C membranes, a high energy density of 43.0 Wh kg^(-1) at a power density of800 W kg^(-1) was observed. Moreover, the device also showed good cycling stability of 82.9% at a current density of 1.0 A g^(-1) after 8000 cycles. This work may throw a light on simply the fabrication of other high-performance transition-metal nitridebased supercapacitor or other energy storage devices.展开更多
Computer-assisted chemical structure searching plays a critical role for efficient structure screening in cheminformatics. We designed a high-performance chemical structure & data search engine called DCAIKU, buil...Computer-assisted chemical structure searching plays a critical role for efficient structure screening in cheminformatics. We designed a high-performance chemical structure & data search engine called DCAIKU, built on CouchDB and ElasticSearch engines. DCAIKU converts the chemical structure similarity search problem into a general text search problem to utilize off-the-shelf full-text search engines. DCAIKU also supports flexible document structures and heterogeneous datasets with the help of schema-less document database. Our evaluations show that DCAIKU can handle both keyword search and structural search against millions of records with both high accuracy and low latency. We expect that DCAIKU will lay the foundation towards large-scale and cost-effective structural search in materials science and chemistry research.展开更多
Supercapacitors with unique performance have been widely utilized in many fields. Herein, we report a nitrogen and sulfur co-doped graphene aerogel(N/S-GA-2) prepared using a low toxic precursor for high-performance s...Supercapacitors with unique performance have been widely utilized in many fields. Herein, we report a nitrogen and sulfur co-doped graphene aerogel(N/S-GA-2) prepared using a low toxic precursor for high-performance supercapacitors. The as-obtained material possesses a hierarchically porous structure and a large number of electrochemical active sites. At a current density of 1 Ag^-1, the specific capacitance of the N/S-GA-2 for supercapacitors with the ionic liquid as the electrolyte is 169.4 Fg^-1, and the corresponding energy density is 84.5 Wh kg^-1.At a power density of 8.9 k W kg^-1, the energy density can reach up to 75.7 Wh kg^-1, showing that the N/S-GA-2 has an excellent electrochemical performance. Consequently, the N/S-GA-2 can be used as a promising candidate of electrode materials for supercapacitors with high power density and high energy density.展开更多
Dual-asymmetric poly（vinylidene fluoride） （PVDF） separators have been fabricated by thermally induced phase separation with dimethyl sulfone （DMSO2） and glycerol as mixed diluents. The separators have a porous b...Dual-asymmetric poly（vinylidene fluoride） （PVDF） separators have been fabricated by thermally induced phase separation with dimethyl sulfone （DMSO2） and glycerol as mixed diluents. The separators have a porous bulk with large interconnected pores （-1.0 μm） and two surfaces with small pores （-30 nm）. This dual-asymmetric porous structure endows the separators with higher electrolyte uptake amount and rapider uptake rate, as well as better electrolyte retention ability than the commercialized Celgard 2400. The separators even maintain their dimensional stability up to 160 ℃, at which temperature the surface pores close up, leading to a dramatic decrease of air permeability. The electrolyte filled separators also show high ion conductivity （1.72 mS.cm-1） at room temperature. Lithium iron phosphate （LiFePO4）/lithium （Li） cells using these separators display superior discharge capacity and better rate performance as compared with those from the commercialized ones. The results provide new insight into the design and development of separators for high-performance lithium ion batteries with enhanced safety.展开更多
By means of isothermal compression at temperatures in the range of 650-900℃and strain rates in the range of 0.001-1 s^(-1),the dynamic recrystallization behavior and microstructural evolution of a Cu-3.28 Ni-0.6 Si-0...By means of isothermal compression at temperatures in the range of 650-900℃and strain rates in the range of 0.001-1 s^(-1),the dynamic recrystallization behavior and microstructural evolution of a Cu-3.28 Ni-0.6 Si-0.22 Zn-0.11 Cr-0.04 P(wt%)alloy designed by a machine learning method were investigated.A semiempirical constitutive equation,processing maps and an average activation energy were generated.The microstructure under different conditions and the effect of strain rate on the texture of the alloy at 800-900℃were observed.The results show that the suitable temperature is800-900℃;when the strain is less than 0.4,the appropriate strain rate is 0.01-0.5 s^(-1);and when the strain is greater than 0.4,the appropriate strain rate is below0.05 s^(-1).After deformation at 800℃,the main texture changed from{112}<111>of copper to a uniform distribution with the increase in strain rate,but the sample did not have obvious texture after deformation at 850 and900℃.The above results can provide a reference for the selection of process parameters.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
Potassium-ion batteries(KIBs)are a potential candidate to lithium-ion batteries(LIBs)but possess unsatisfactory capacity and rate properties.Herein,the metallic cobalt selenide quantum dots(Co0.85Se-QDs)encapsulated i...Potassium-ion batteries(KIBs)are a potential candidate to lithium-ion batteries(LIBs)but possess unsatisfactory capacity and rate properties.Herein,the metallic cobalt selenide quantum dots(Co0.85Se-QDs)encapsulated in mesoporous carbon matrix were designed via a direct hydrothermal method.Specifically,the cobalt selenide/carbon composite(Co0.85Se-QDs/C)possesses tertiary hierarchical structure,which is the primary quantum dots,the secondary petals flake,and the tertiary hollow micropolyhedron framework.Co0.85Se-QDs are homogenously embedded into the carbon petals flake,which constitute the hollow polyhedral framework.This unique structure can take the advantages of both nanoscale and microscale features:Co0.85Se-QDs can expand in a multidimensional and ductile carbon matrix and reduce the K-intercalation stress in particle dimensions;the micropetals can restrain the agglomeration of active materials and promote the transportation of potassium ion and electron.In addition,the hollow carbon framework buffers volume expansion,maintains the structural integrity,and increases the electronic conductivity.Benefiting from this tertiary hierarchical structure,outstanding K-storage performance(402 mAh g?1 after 100 cycles at 50 mA g?1)is obtained when Co0.85Se-QDs/C is used as KIBs anode.More importantly,the selenization process in this work is newly reported and can be generally extended to prepare other quantum dots encapsulated in edge-limited frameworks for excellent energy storage.展开更多
Two-dimensional(2D)MXenes are promising as electrode materials for energy storage,owing to their high electronic conductivity and low diffusion barrier.Unfortunately,similar to most 2D materials,MXene nanosheets easil...Two-dimensional(2D)MXenes are promising as electrode materials for energy storage,owing to their high electronic conductivity and low diffusion barrier.Unfortunately,similar to most 2D materials,MXene nanosheets easily restack during the electrode preparation,which degrades the electrochemical performance of MXene-based materials.A novel synthetic strategy is proposed for converting MXene into restacking-inhibited three-dimensional(3D)balls coated with iron selenides and carbon.This strategy involves the preparation of Fe_(2)O_(3)@carbon/MXene microspheres via a facile ultrasonic spray pyrolysis and subsequent selenization process.Such 3D structuring effectively prevents interlayer restacking,increases the surface area,and accelerates ion transport,while maintaining the attractive properties of MXene.Furthermore,combining iron selenides and carbon with 3D MXene balls offers many more sites for ion storage and enhances the structural robustness of the composite balls.The resultant 3D structured microspheres exhibit a high reversible capacity of 410 mAh g^(−1) after 200 cycles at 0.1 A g^(−1) in potassium-ion batteries,corresponding to the capacity retention of 97% as calculated based on 100 cycles.Even at a high current density of 5.0 A g^(−1),the composite exhibits a discharge capacity of 169 mAh g^(−1).展开更多
In order to improve mechanical and corrosion properties of biodegradable pure Zn,a knowledge-based microstructure design is performed on Zn-Li alloy system composed of hard β-LiZn_(4) and soft Zn phases.Precipitation...In order to improve mechanical and corrosion properties of biodegradable pure Zn,a knowledge-based microstructure design is performed on Zn-Li alloy system composed of hard β-LiZn_(4) and soft Zn phases.Precipitation and multi-modal grain structure are designed to toughen β-LiZn_(4) while strengthen Zn,resulting in high strength and high ductility for both the phases.Needle-like secondary Zn precipitates form in β-LiZn4,while fine-scale networks of string-like β-LiZn4 precipitates form in Zn with a tri-modal grain structure.As a result,near-eutectic Zn-0.48 Li alloy with an outstanding combination of high strength and high ductility has been fabricated through hot-warm rolling,a novel fabrication process to realize the microstructure design.The as-rolled alloy has yield strength(YS) of 246 MPa,the ultimate tensile strength(UTS) of 395 MPa and elongation to failure(EL) of 47 %.Immersion test in simulated body fluid(SBF) for 30 days reveals that Li-rich products form preferentially at initial stage,followed by Zn-rich products with prolonged time.Aqueous insoluble Li_(2) CO_(3) forms a protective passivation film on the alloy surface,which suppresses the average corrosion rate from 81.2 μm/year at day one down dramatically to 18.2 μm/year at day five.Afterwards,the average corrosion rate increases slightly with decrease of Li2 CO_(3) content,which undulates around the clinical requirements on corrosion resistance(i.e.,20 μm/year) claimed for biodegradable metal stents.展开更多
基金Corresponding author:Jiang Haitao,Ph.D.,Professor,Institute of Engineering Technology,University of Science and Technology Beijing,Beijing 102206,P.R.China,Tel:0086-10-62332598,E-mail:jianght@ustb.edu.cn。
文摘AZ31 magnesium alloy was used as the object of study to fabricate an alloy with the bimodal grain structure using singlepass hot rolling,and to explore how this structure enhances the strength and plasticity of the alloy.The results show that the formation of the bimodal grain structure is more pronounced at rolling temperatures ranging from 350°C to 450°C,especially under conditions of large reduction(≥40%).The optimized proportion and distribution of the bimodal grain structure play a pivotal role in simultaneously enhancing the strength and ductility of the alloy,significantly impacting the mechanical properties.The rolled sheet with the bimodal grain structure achieves an ultimate tensile strength of 258.3 MPa and an elongation of 17.1%under a rolling reduction of 40%with the rolling rate of 75 m/min and rolling temperature of 400°C.Adjusting rolling parameters,including temperature,reduction ratio and rolling rate,is crucial for optimizing the bimodal grain structure,thereby achieving a balance between plasticity improvement and high strength maintenance.
基金financially supported by the Fundamental Research Funds for the Central Universities,North Minzu University(No.2020KYQD18)the Key Research and Development Program(Talents Introduction Project)of Ningxia(No.2021BEB04027)+1 种基金the Fundamental Research Funds for the Central Universities,North Minzu University(No.2021KJCX04)the Natural Science Foundation of Ningxia Province(No.2022AAC05033)
文摘With the rapid development of flexible equipment,high-energy/-power requirements have been proposed for energy storage devices.Nevertheless,the poor conductivities of metallic oxides and their low levels of transmission of electrons/ions hinder their widespread application.Here,a sandwich-structured Co_(3)O_(4)-Fe_(3)O_(4)(CFO) composite with binder-free was synthesized on a carbon cloth substrate via co-precipitation and partial ion exchange.The appropriate substitution of Co_(3)O_(4)with Fe_(3)O_(4)is favorable in promoting the rapid transfer of electrolyte ions and alleviating changes in volume during the electrochemical studies.When the duration of the substitution reaction is 20 min,the obtained electrode delivers a maximum specific capacitance of 1196.2 Fg^(-1)at a current density of 1 A g^(-1)and a superior capacity retention of~71%when the current density varies from 1to 30 Ag^(-1).Furthermore,the fabricated CFO//activated carbon flexible all-solid-state supercapacitor exhibits arespective maximum energy and power density of 68.7Wh kg^(-1)and 16,000 W kg^(-1)and excellent flexibility.It also displays a specific capacity retention of 81.3%under four continuous bending states at a current density of 6A g^(-1)over 10,000 cycles.These remarkable electrochemical char ac teristics suggest that the sandwich-structured CFO composite displays considerable potential for application in flexible high-energy/-power supercapacitors.
基金supported by the National Natural Science Foundation of China(NSFC)(22105059,22179078,22479115)the Beijing-Tianjin-Hebei Basic Research Cooperation Special Project(B2024204027)+5 种基金the Youth Top-notch Talent Foundation of Hebei Provincial Universities(BJK2022023)the Natural Science Foundation of Hebei Province(B2023204006)the talent training project of Hebei province(No.B20231004)the Innovative Research Team of High-level Local Universities in ShanghaiZhejiang Provincial Natural Science Foundation of China(LY24E020002)Wenzhou basic scientific research project(G20240022)。
文摘Sodium-ion batteries have emerged as promising candidates for next-generation large-scale energy storage systems due to the abundance of sodium resources,low solvation energy,and cost-effectiveness.Among the available cathode materials,vanadium-based sodium phosphate cathodes are particularly notable for their high operating voltage,excellent thermal stability,and superior cycling performance.However,these materials face significant challenges,including sluggish reaction kinetics,the toxicity of vanadium,and poor electronic conductivity.To overcome these limitations and enhance electrochemical performance,various strategies have been explored.These include morphology regulation via diverse synthesis routes and electronic structure optimization through metal doping,which effectively improve the diffusion of Na+and electrons in vanadium-based phosphate cathodes.This review provides a comprehensive overview of the challenges associated with V-based polyanion cathodes and examines the role of morphology and electronic structure design in enhancing performance.Key vanadium-based phosphate frameworks,such as orthophosphates(Na_(3)V_(2)(PO_(4))_(3)),pyrophosphates(NaVP_(2)O_(7),Na_(2)(VO)P_(2)O_(7),Na_(7)V_(3)(P_(2)O_(7))_(4)),and mixed phosphates(Na_(7)V_(4)(P_(2)O_(7))_(4)PO_(4)),are discussed in detail,highlighting recent advances and insights into their structure-property relationships.The design of cathode material morphology offers an effective approach to optimizing material structures,compositions,porosity,and ion/electron diffusion pathways.Simultaneously,electronic structure tuning through element doping allows for the regulation of band structures,electron distribution,diffusion barriers,and the intrinsic conductivity of phosphate compounds.Addressing the challenges associated with vanadium-based sodium phosphate cathode materials,this study proposes feasible solutions and outlines future research directions toward advancement of high-performance vanadium-based polyanion cathodes.
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.52202371 and 51902102)the Natural Science Foundation of Shandong Province(Nos.ZR202211230173,ZR2020QE066 and ZR2021QE200)+2 种基金the Opening Project of State Key Laboratory of Advanced Technology for Float Glass(No.2020KF08)the SDUT&Zibo City Integration Development Project(No.2021SNPT0045)the fellowship of China Postdoctoral Science Foundation(No.2020M672081).
文摘Transition metal carbonates(TMCs)hold great potential as high-performance electrodes for alkali metal-ion batteries,owing to multiple-ion storage mechanisms involving conversion process and electrocatalytic reaction.However,they still suffer from inferior electronic conductivity and volume variation during delithiation/lithiation.Heterostructure and heteroatoms doping offer immense promise in enhancing reaction kinetics and structural integrity,which unfortunately have not been achieved in TMCs.Herein,a unique TMCs heterostructure with Ni-doped MnCO_(3)as“core”and Mn-doped NiCO_(3)as“shell”,which is wrapped by graphene(NM@MN/RGO),is achieved by cations differentiation strategy.The formation process for core-shell NM@MN consists of epitaxial growth of NiCO_(3)from MnCO_(3)and synchronously mutual doping,owing to the similar crystal structures but different solubility product constant/formation energy of MnCO_(3)and NiCO_(3).In-situ electrochemical impedance spectroscopy,galvanostatic intermittent titration technique,differential capacity versus voltage plots,theoretical calculation and kinetic analysis reveal the superior electrochemical activity of the NM@MN/RGO to MnCO_(3)/RGO.The NM@MN/RGO shows excellent lithium storage properties(1013.4 mAh·g^(-1)at 0.1 A·g^(-1)and 760 mAh·g^(-1)after 1000 cycles at 2 A·g^(-1))and potassium storage properties(capacity decay rate of 0.114 mAh·g^(-1)per cycle).This work proposes an efficient cation differentiation strategy for constructing advanced TMC electrodes.
基金supported by the National Natural Science Foundation of China(52372099,52202328,22461142135,22479046)the Shanghai Sailing Program(22YF1455500)the Shanghai Magnolia Talent Plan Pujiang Project(24PJD128)。
文摘Solid-state polymer electrolytes are crucial for advancing solid-state lithium-metal batteries owing to their flexibility,excellent manufacturability,and strong interfacial compatibility.However,their widespread applications are hindered by low ionic conductivity at room temperature and lithium dendrite growth.Herein,we report a novel solid-state composite membrane electrolyte design that combines the vertically aligned channel structure and copolymer with a radial gradient composition.Within the vertically aligned channels,the composition of poly(vinyl ethylene carbonate-co-poly(ethylene glycol)diacrylate)(P(VEC-PEGDA)varies in a gradient along the radial direction:from the center to the wall of vertically aligned channels,the proportion of vinyl ethylene carbonate(VEC)in the copolymer decreases,while the proportion of poly(ethylene glycol)diacrylate(PEGDA)increases accordingly.It can be functionally divided into a mechanical-reinforcement layer and a fast-ion-conducting layer.The resulting solid-state composite membrane electrolyte achieves a high critical current density of 1.2 mA cm^(-2)and high ionic conductivity of 2.03 mS cm^(-1)at room temperature.Employing this composite membrane electrolyte,a Li//Li symmetric cell exhibits stable cycling for over 1850 h at 0.2 m A cm^(-2)/0.2 m A h cm^(-2),and a Li//LiFePO4(LFP)battery maintains 77.3% capacity retention at 2 C after 300 cycles.Our work provides insight into the rational design of safer and more efficient solidstate batteries through electrolyte structural engineering.
文摘Six new lanthanide complexes:[Ln(3,4-DEOBA)3(4,4'-DM-2,2'-bipy)]2·2C_(2)H_(5)OH,[Ln=Dy(1),Eu(2),Tb(3),Sm(4),Ho(5),Gd(6);3,4-DEOBA-=3,4-diethoxybenzoate,4,4'-DM-2,2'-bipy=4,4'-dimethyl-2,2'-bipyridine]were successfully synthesized by the volatilization of the solution at room temperature.The crystal structures of six complexes were determined by single-crystal X-ray diffraction technology.The results showed that the complexes all have a binuclear structure,and the structures contain free ethanol molecules.Moreover,the coordination number of the central metal of each structural unit is eight.Adjacent structural units interact with each other through hydrogen bonds and further expand to form 1D chain-like and 2D planar structures.After conducting a systematic study on the luminescence properties of complexes 1-4,their emission and excitation spectra were obtained.Experimental results indicated that the fluorescence lifetimes of complexes 2 and 3 were 0.807 and 0.845 ms,respectively.The emission spectral data of complexes 1-4 were imported into the CIE chromaticity coordinate system,and their corre sponding luminescent regions cover the yellow light,red light,green light,and orange-red light bands,respectively.Within the temperature range of 299.15-1300 K,the thermal decomposition processes of the six complexes were comprehensively analyzed by using TG-DSC/FTIR/MS technology.The hypothesis of the gradual loss of ligand groups during the decomposition process was verified by detecting the escaped gas,3D infrared spectroscopy,and ion fragment information detected by mass spectrometry.The specific decomposition path is as follows:firstly,free ethanol molecules and neutral ligands are removed,and finally,acidic ligands are released;the final product is the corresponding metal oxide.CCDC:2430420,1;2430422,2;2430419,3;2430424,4;2430421,5;2430423,6.
基金Supported by the Science and Technology Cooperation and Exchange special project of Cooperation of Shanxi Province(202404041101014)the Fundamental Research Program of Shanxi Province(202403021212333)+3 种基金the Joint Funds of the National Natural Science Foundation of China(U24A20555)the Lvliang Key R&D of University-Local Cooperation(2023XDHZ10)the Initiation Fund for Doctoral Research of Taiyuan University of Science and Technology(20242026)the Outstanding Doctor Funding Award of Shanxi Province(20242080).
文摘To elucidate the effect of calcite-regulated activated carbon(AC)structure on low-temperature denitrification performance of SCR catalysts,this work prepared a series of Mn-Ce/De-AC-xCaCO_(3)(x is the calcite content in coal)catalysts were prepared by the incipient wetness impregnation method,followed by acid washing to remove calcium-containing minerals.Comprehensive characterization and low-temperature denitrification tests revealed that calcite-induced structural modulation of coal-derived AC significantly enhances catalytic activity.Specifically,NO conversion increased from 88.3%of Mn-Ce/De-AC to 91.7%of Mn-Ce/De-AC-1CaCO_(3)(210℃).The improved SCR denitrification activity results from the enhancement of physicochemical properties including higher Mn^(4+)content and Ce^(4+)/Ce^(3+)ratio,an abundance of chemisorbed oxygen and acidic sites,which could strengthen the SCR reaction pathways(richer NH_(3)activated species and bidentate nitrate active species).Therefore,NO removal is enhanced.
基金Supported by the National Key Research Program(No.2024-1129-954-112)National Natural Science Foundation of China(No.52372033)Guangxi Science and Technology Major Program(No.AA24263054)。
文摘Alkali-free SiO_(2)-Al_(2)O_(3)-CaO-MgO with different SiO_(2)/Al_(2)O_(3)mass ratios was prepared by conventional melt quenching method.The glass network structure,thermodynamic properties and elastic modulus changes with SiO_(2)and Al_(2)O_(3)ratios were investigated using various techniques.It is found that when SiO_(2)is replaced by Al_(2)O_(3),the Q^(4) to Q^(3) transition of silicon-oxygen network decreases while the aluminum-oxygen network increases,which result in the transformation of Si-O-Si bonds to Si-O-Al bonds and an increase in glass network connectivity even though the intermolecular bond strength decreases.The glass transition temperature(T_(g))increases continuously,while the thermal expansion coefficient increases and high-temperature viscosity first decreases and then increases.Meanwhile,the elastic modulus values increase from 93 to 102 GPa.This indicates that the elastic modulus is mainly affected by packing factor and dissociation energy,and elements with higher packing factors and dissociation energies supplant those with lower values,resulting in increased rigidity within the glass.
基金Funded by the National Natural Science Foundation of China(Nos.5226804252468035)。
文摘To investigate the pore structure of graphene oxide modified polymer cement mortar(GOPM)under salt-freeze-thaw(SFT)coupling effects and its impact on deterioration,this study modifies polymer cement mortar(EMCM)with graphene oxide(GO).The micro-pore structure of GOPM is characterized using LF-NMR and SEM.Fractal theory is applied to calculate the fractal dimension of pore volume,and the deterioration patterns are analyzed based on the evolution characteristics of capillary pores.The experimental results indicate that,after 25 salt-freeze-thaw cycles(SFTc),SO2-4 ions penetrate the matrix,generating corrosion products that fill existing pores and enhance the compactness of the specimen.As the number of cycles increases,the ongoing formation and expansion of corrosion products within the matrix,combined with persistent freezing forces,and result in the degradation of the pore structure.Therefore,the mass loss rate(MLR)of the specimens shows a trend of first decreasing and then increasing,while the relative dynamic elastic modulus(RDEM)initially increases and then decreases.Compared to the PC group specimens,the G3PM group specimens show a 28.71% reduction in MLR and a 31.42% increase in RDEM after 150 SFTc.The fractal dimensions of the transition pores,capillary pores,and macropores in the G3PM specimens first increase and then decrease as the number of SFTc increases.Among them,the capillary pores show the highest correlation with MLR and RDEM,with correlation coefficients of 0.97438 and 0.98555,respectively.
基金supported by National Natural Science Foundation of China(No.52025055 and 52275571)Basic Research Operation Fund of China(No.xzy012024024).
文摘Tilted metasurface nanostructures,with excellent physical properties and enormous application potential,pose an urgent need for manufacturing methods.Here,electric-field-driven generative-nanoimprinting technique is proposed.The electric field applied between the template and the substrate drives the contact,tilting,filling,and holding processes.By accurately controlling the introduced included angle between the flexible template and the substrate,tilted nanostructures with a controllable angle are imprinted onto the substrate,although they are vertical on the template.By flexibly adjusting the electric field intensity and the included angle,large-area uniform-tilted,gradient-tilted,and high-angle-tilted nanostructures are fabricated.In contrast to traditional replication,the morphology of the nanoimprinting structure is extended to customized control.This work provides a cost-effective,efficient,and versatile technology for the fabrication of various large-area tilted metasurface structures.As an illustration,a tilted nanograting with a high coupling efficiency is fabricated and integrated into augmented reality displays,demonstrating superior imaging quality.
基金Supported by the Key Science&Technology Project of Guangzhou(No.202103000045)the National Natural Science Foundation of China(No.82070972,No.82271093).
文摘AIM:To investigate the effects of shortening the duration of silicone oil tamponade on retinal structure and function in patients undergoing silicone oil removal(SOR)after surgery for primary rhegmatogenous retinal detachment(RRD).METHODS:A total of 58 eligible patients were enrolled and randomly assigned to two groups based on tamponade duration:the short-term group(30-45d)and the conventional group(≥90d).Comprehensive evaluations were performed before and after SOR,including slitlamp examination,best-corrected visual acuity(BCVA)measurement,intraocular pressure(IOP)testing,optical coherence tomography(OCT),optical coherence tomography angiography(OCTA),microperimetry,electroretinography(ERG),and visual evoked potential(VEP)assessment.RESULTS:A total of 33 patients(23 males and 10 females;33 eyes)were enrolled in the short-term SO tamponade group with mean age of 52.45±9.35y,and 25 patients(15 males and 10 females;25 eyes)were enrolled in the conventional SO tamponade group with mean age of 50.80±12.06y.Compared with the conventional group,the short-term silicone oil tamponade group had a significantly lower incidence of silicone oil emulsification and cataract progression,with no significant difference in retinal reattachment success rate.Structurally,short-term tamponade was associated with increased thickness of the retinal ganglion cell layer(RGCL)in the nasal and superior macular regions and improved recovery of superficial retinal vascular density in these areas.Functionally,the shortterm group showed better BCVA and retinal sensitivity both before and 1mo after SOR;additionally,the P100 amplitude in VEP tests was significantly increased in this group.CONCLUSION:Shortening the duration of silicone oil tamponade effectively reduces damage to retinal structure and function without compromising the success rate of retinal reattachment in patients with primary RRD.
基金supported by the National Natural Science Foundation of China (51203071,51363014,51463012,and 51763014)China Postdoctoral Science Foundation (2014M552509 and 2015T81064)+2 种基金Natural Science Funds of the Gansu Province (1506RJZA098)the Program for Hongliu Distinguished Young Scholars in Lanzhou University of Technology (J201402)Joint fund between Shenyang National Laboratory for Materials Science and State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals (18LHPY002)
文摘Transition-metal nitrides exhibit wide potential windows and good electrochemical performance, but usually experience imbalanced practical applications in the energy storage field due to aggregation, poor circulation stability, and complicated syntheses. In this study, a novel and simple multiphase polymeric strategy was developed to fabricate hybrid vanadium nitride/carbon(VN/C) membranes for supercapacitor negative electrodes, in which VN nanoparticles were uniformly distributed in the hierarchical porous carbon 3D networks. The supercapacitor negative electrode based on VN/C membranes exhibited a high specific capacitance of 392.0 F g^(-1) at 0.5 A g^(-1) and an excellent rate capability with capacitance retention of 50.5% at 30 A g^(-1). For the asymmetric device fabricated using Ni(OH)_2//VN/C membranes, a high energy density of 43.0 Wh kg^(-1) at a power density of800 W kg^(-1) was observed. Moreover, the device also showed good cycling stability of 82.9% at a current density of 1.0 A g^(-1) after 8000 cycles. This work may throw a light on simply the fabrication of other high-performance transition-metal nitridebased supercapacitor or other energy storage devices.
基金This work was supported by the National Natural Science Foundation of China,the Ministry of Science and Technology of China,and the Swedish Research Council.
文摘Computer-assisted chemical structure searching plays a critical role for efficient structure screening in cheminformatics. We designed a high-performance chemical structure & data search engine called DCAIKU, built on CouchDB and ElasticSearch engines. DCAIKU converts the chemical structure similarity search problem into a general text search problem to utilize off-the-shelf full-text search engines. DCAIKU also supports flexible document structures and heterogeneous datasets with the help of schema-less document database. Our evaluations show that DCAIKU can handle both keyword search and structural search against millions of records with both high accuracy and low latency. We expect that DCAIKU will lay the foundation towards large-scale and cost-effective structural search in materials science and chemistry research.
基金Financial support from the National Natural Science Foundation of China (Nos. 21873026 and 21573058)the Program for Innovative Research Team in Science and Technology in University of Henan Province (17IRTSTHN 001) is gratefully acknowledged
文摘Supercapacitors with unique performance have been widely utilized in many fields. Herein, we report a nitrogen and sulfur co-doped graphene aerogel(N/S-GA-2) prepared using a low toxic precursor for high-performance supercapacitors. The as-obtained material possesses a hierarchically porous structure and a large number of electrochemical active sites. At a current density of 1 Ag^-1, the specific capacitance of the N/S-GA-2 for supercapacitors with the ionic liquid as the electrolyte is 169.4 Fg^-1, and the corresponding energy density is 84.5 Wh kg^-1.At a power density of 8.9 k W kg^-1, the energy density can reach up to 75.7 Wh kg^-1, showing that the N/S-GA-2 has an excellent electrochemical performance. Consequently, the N/S-GA-2 can be used as a promising candidate of electrode materials for supercapacitors with high power density and high energy density.
基金financially supported by the National Natural Science Foundation of China(Nos.21174124 and 21534009)
文摘Dual-asymmetric poly（vinylidene fluoride） （PVDF） separators have been fabricated by thermally induced phase separation with dimethyl sulfone （DMSO2） and glycerol as mixed diluents. The separators have a porous bulk with large interconnected pores （-1.0 μm） and two surfaces with small pores （-30 nm）. This dual-asymmetric porous structure endows the separators with higher electrolyte uptake amount and rapider uptake rate, as well as better electrolyte retention ability than the commercialized Celgard 2400. The separators even maintain their dimensional stability up to 160 ℃, at which temperature the surface pores close up, leading to a dramatic decrease of air permeability. The electrolyte filled separators also show high ion conductivity （1.72 mS.cm-1） at room temperature. Lithium iron phosphate （LiFePO4）/lithium （Li） cells using these separators display superior discharge capacity and better rate performance as compared with those from the commercialized ones. The results provide new insight into the design and development of separators for high-performance lithium ion batteries with enhanced safety.
基金financially supported by the National Key Research and Development Program of China(No.2016YFB0301300)the National Natural Science Foundation of China(Nos.51974028 and U1602271)。
文摘By means of isothermal compression at temperatures in the range of 650-900℃and strain rates in the range of 0.001-1 s^(-1),the dynamic recrystallization behavior and microstructural evolution of a Cu-3.28 Ni-0.6 Si-0.22 Zn-0.11 Cr-0.04 P(wt%)alloy designed by a machine learning method were investigated.A semiempirical constitutive equation,processing maps and an average activation energy were generated.The microstructure under different conditions and the effect of strain rate on the texture of the alloy at 800-900℃were observed.The results show that the suitable temperature is800-900℃;when the strain is less than 0.4,the appropriate strain rate is 0.01-0.5 s^(-1);and when the strain is greater than 0.4,the appropriate strain rate is below0.05 s^(-1).After deformation at 800℃,the main texture changed from{112}<111>of copper to a uniform distribution with the increase in strain rate,but the sample did not have obvious texture after deformation at 850 and900℃.The above results can provide a reference for the selection of process parameters.
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financially supported by Beijing Natural Science Foundation(No.2192034)China Postdoctoral Science Foundation(No.2018M631335)National Key R&D Program of China(No.2018YFB0905600).
文摘Potassium-ion batteries(KIBs)are a potential candidate to lithium-ion batteries(LIBs)but possess unsatisfactory capacity and rate properties.Herein,the metallic cobalt selenide quantum dots(Co0.85Se-QDs)encapsulated in mesoporous carbon matrix were designed via a direct hydrothermal method.Specifically,the cobalt selenide/carbon composite(Co0.85Se-QDs/C)possesses tertiary hierarchical structure,which is the primary quantum dots,the secondary petals flake,and the tertiary hollow micropolyhedron framework.Co0.85Se-QDs are homogenously embedded into the carbon petals flake,which constitute the hollow polyhedral framework.This unique structure can take the advantages of both nanoscale and microscale features:Co0.85Se-QDs can expand in a multidimensional and ductile carbon matrix and reduce the K-intercalation stress in particle dimensions;the micropetals can restrain the agglomeration of active materials and promote the transportation of potassium ion and electron.In addition,the hollow carbon framework buffers volume expansion,maintains the structural integrity,and increases the electronic conductivity.Benefiting from this tertiary hierarchical structure,outstanding K-storage performance(402 mAh g?1 after 100 cycles at 50 mA g?1)is obtained when Co0.85Se-QDs/C is used as KIBs anode.More importantly,the selenization process in this work is newly reported and can be generally extended to prepare other quantum dots encapsulated in edge-limited frameworks for excellent energy storage.
基金supported by the National Research Foundation of Korea(NRF)grant funded by Korea government(NRF-2019R1A2C2088047 and NRF-2020R1C1C1003375).
文摘Two-dimensional(2D)MXenes are promising as electrode materials for energy storage,owing to their high electronic conductivity and low diffusion barrier.Unfortunately,similar to most 2D materials,MXene nanosheets easily restack during the electrode preparation,which degrades the electrochemical performance of MXene-based materials.A novel synthetic strategy is proposed for converting MXene into restacking-inhibited three-dimensional(3D)balls coated with iron selenides and carbon.This strategy involves the preparation of Fe_(2)O_(3)@carbon/MXene microspheres via a facile ultrasonic spray pyrolysis and subsequent selenization process.Such 3D structuring effectively prevents interlayer restacking,increases the surface area,and accelerates ion transport,while maintaining the attractive properties of MXene.Furthermore,combining iron selenides and carbon with 3D MXene balls offers many more sites for ion storage and enhances the structural robustness of the composite balls.The resultant 3D structured microspheres exhibit a high reversible capacity of 410 mAh g^(−1) after 200 cycles at 0.1 A g^(−1) in potassium-ion batteries,corresponding to the capacity retention of 97% as calculated based on 100 cycles.Even at a high current density of 5.0 A g^(−1),the composite exhibits a discharge capacity of 169 mAh g^(−1).
基金financially supported by the National Key R&D Program of China(No.2016YFC1102500)the National Natural Science Foundation of China(No.51871020)the Fundamental Research Funds for the Central Universities(No.FRF-TP-19022A3Z)。
文摘In order to improve mechanical and corrosion properties of biodegradable pure Zn,a knowledge-based microstructure design is performed on Zn-Li alloy system composed of hard β-LiZn_(4) and soft Zn phases.Precipitation and multi-modal grain structure are designed to toughen β-LiZn_(4) while strengthen Zn,resulting in high strength and high ductility for both the phases.Needle-like secondary Zn precipitates form in β-LiZn4,while fine-scale networks of string-like β-LiZn4 precipitates form in Zn with a tri-modal grain structure.As a result,near-eutectic Zn-0.48 Li alloy with an outstanding combination of high strength and high ductility has been fabricated through hot-warm rolling,a novel fabrication process to realize the microstructure design.The as-rolled alloy has yield strength(YS) of 246 MPa,the ultimate tensile strength(UTS) of 395 MPa and elongation to failure(EL) of 47 %.Immersion test in simulated body fluid(SBF) for 30 days reveals that Li-rich products form preferentially at initial stage,followed by Zn-rich products with prolonged time.Aqueous insoluble Li_(2) CO_(3) forms a protective passivation film on the alloy surface,which suppresses the average corrosion rate from 81.2 μm/year at day one down dramatically to 18.2 μm/year at day five.Afterwards,the average corrosion rate increases slightly with decrease of Li2 CO_(3) content,which undulates around the clinical requirements on corrosion resistance(i.e.,20 μm/year) claimed for biodegradable metal stents.
