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
This study presents a novel approach to enhance silicon anode performance through barium titanate(BTO)incorporation,with the establishment of a force-electric coupling model.By introducing piezoelectric BTO into silic...This study presents a novel approach to enhance silicon anode performance through barium titanate(BTO)incorporation,with the establishment of a force-electric coupling model.By introducing piezoelectric BTO into silicon matrices,we successfully improved both the mechanical stability and electrochemical kinetics of the anode.The developed force-electric coupling model explains how BTO mitigates stress accumulation during lithiation while optimizing the kinetics of Li^(+)and electron transfer.Experimental verification and multiphysical simulation indicate that Si@BTO effectively eliminates structural degradation during the cycling process and significantly reduces the charge transfer resistance.The force-electric coupling mechanism further facilitates stable solid electrolyte interphase(SEI)formation.When paired with LiFePO_(4)cathodes,Si@BTO maintains 76% capacity retention after 500 cycles at a 10 C rate.This work establishes a basic force-electric coupling model framework and offers insights into the development of advanced silicon anode batteries with exceptional performance.展开更多
The rapid expansion of the automotive sector has significantly increased the demand for highperformance lithium-ion batteries,positioning Ni-rich layered cathodes as a promising solution due to their high energy densi...The rapid expansion of the automotive sector has significantly increased the demand for highperformance lithium-ion batteries,positioning Ni-rich layered cathodes as a promising solution due to their high energy density and cost-efficiency.However,these cathodes face critical challenges,including thermal instability and structural degradation at an elevated temperature,which hinder their practical application.This study introduces an advanced surface reconstruction strategy combining a LiScF_(4)coating,Sc/F surface co-doping,and a cation-mixing layer to address these issues.The LiScF_(4)coating serves as a durable protective barrier,reducing electrolyte decomposition,minimizing transition metal dissolution,and enhancing lithium-ion transport.Sc/F surface co-doping stabilizes lattice oxygen by increasing the energy barrier for oxygen vacancy formation and minimizing oxygen release,thereby suppressing phase transitions and interfacial side reactions.Additionally,the cation-mixing layer improves interfacial stability by alleviating lattice strain and supporting reversible cation migration,ensuring prolonged durability during cycling and under high-temperature conditions.These integrated modifications work synergistically to mitigate various degradation mechanisms,significantly improving the thermal stability,structural integrity,and electrochemical performance of Ni-rich cathodes.This approach offers a viable pathway for incorporating Ni-rich cathodes into advanced lithium-ion batteries,making them well-suited for applications requiring high thermal stability.Moreover,this research provides valuable guidance for the development of a multi-component modification strategy,paving the way for future innovations in energy storage materials and advancing high-performance battery technology.展开更多
The heat transfer and stability of methane hydrate in reservoirs have a direct impact on the drilling and production efficiency of hydrate resources,especially in complex stress environments caused by formation subsid...The heat transfer and stability of methane hydrate in reservoirs have a direct impact on the drilling and production efficiency of hydrate resources,especially in complex stress environments caused by formation subsidence.In this study,we investigated the thermal transport and structural stability of methane hydrate under triaxial compression using molecular dynamics simulations.The results suggest that the thermal conductivity of methane hydrate increases with increasing compression strain.Two phonon transport mechanisms were identified as factors enhancing thermal conductivity.At low compressive strains,a low-frequency phonon transport channel was established due to the overlap of phonon vibration peaks between methane and water molecules.At high compressive strains,the filling of larger phonon bandgaps facilitated the opening of more phonon transport channels.Additionally,we found that a strain of0.04 is a watershed point,where methane hydrate transitions from stable to unstable.Furthermore,a strain of0.06 marks the threshold at which the diffusion capacities of methane and water molecules are at their peaks.At a higher strain of0.08,the increased volume compression reduces the available space,limiting the diffusion ability of water and methane molecules within the hydrate.The synergistic effect of the strong diffusion ability and high probability of collision between atoms increases the thermal conductivity of hydrates during the unstable period compared to the stable period.Our findings offer valuable theoretical insights into the thermal conductivity and stability of methane hydrates in reservoir stress environments.展开更多
Layered-type transition metal(TM)oxides are considered as one of the most promising cathodes for K-ion batteries because of the large theoretical gravimetric capacity by low molar mass.However,they suffer from severe ...Layered-type transition metal(TM)oxides are considered as one of the most promising cathodes for K-ion batteries because of the large theoretical gravimetric capacity by low molar mass.However,they suffer from severe structural change by de/intercalation and diffusion of K^(+)ions with large ionic size,which results in not only much lower reversible capacity than the theoretical capacity but also poor power capability.Thus,it is important to enhance the structural stability of the layered-type TM oxides for outstanding electrochemical behaviors under the K-ion battery system.Herein,it is investigated that the substitution of the appropriate Ti^(4+)contents enables a highly enlarged reversible capacity of P3-type KxCrO_(2) using combined studies of first-principles calculation and various experiments.Whereas the pristine P3-type KxCrO_(2) just exhibits the reversible capacity of∼120 mAh g^(−1) in the voltage range of 1.5-4.0 V(vs.K^(+)/K),the∼0.61 mol K^(+)corresponding to∼150 mAh g^(−1) can be reversible de/intercalated at the structure of P3-type K0.71[Cr_(0.75)Ti_(0.25)]O_(2) under the same conditions.Furthermore,even at the high current density of 788 mA g^(−1),the specific capacity of P3-type K0.71[Cr_(0.75)Ti_(0.25)]O_(2) is∼120 mAh g^(−1),which is∼81 times larger than that of the pristine P3-type KxCrO_(2).It is believed that this research can provide an effective strategy to improve the electrochemical performances of the cathode materials suffered by severe structural change that occurred during charge/discharge under not only K-ion battery system but also other rechargeable battery systems.展开更多
With the increasing spotlight in electric vehicles,there is a growing demand for high-energy-density batteries to enhance driving range.Consequently,several studies have been conducted on high-energy-density LiNi_(x)C...With the increasing spotlight in electric vehicles,there is a growing demand for high-energy-density batteries to enhance driving range.Consequently,several studies have been conducted on high-energy-density LiNi_(x)Co_(y)Mn_(z)O_(2)cathodes.However,there is a limit to permanent performance deterioration because of side reactions caused by moisture in the atmosphere and continuous microcracks during cycling as the Ni content to express high energy increases and the content of Mn and Co that maintain structural and electrochemical stabilization decreases.The direct modification of the surface and bulk regions aims to enhance the capacity and long-term performance of high-Ni cathode materials.Therefore,an efficient modification requires a study based on a thorough understanding of the degradation mechanisms in the surface and bulk region.In this review,a comprehensive analysis of various modifications,including doping,coating,concentration gradient,and single crystals,is conducted to solve degradation issues along with an analysis of the overall degradation mechanism occurring in high-Ni cathode materials.It also summarizes recent research developments related to the following modifications,aims to provide notable points and directions for post-studies,and provides valuable references for the commercialization of stable high-energy-density cathode materials.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
Sc and Zn were introduced into O3-NaMn_(0.5)Ni_(0.5)O_(2)(NaMN)using the combination of solution combustion and solid-state method.The effect of Sc and Zn dual-substitution on Na^(+) diffusion dynamics and structural ...Sc and Zn were introduced into O3-NaMn_(0.5)Ni_(0.5)O_(2)(NaMN)using the combination of solution combustion and solid-state method.The effect of Sc and Zn dual-substitution on Na^(+) diffusion dynamics and structural stability of NaMN was investigated.The physicochemical characterizations suggest that the introduction of Sc and Zn broaden Na^(+) diffusion channels and weaken the Na—O bonds,thereby facilitating the diffusion of sodium ions.Simulations indicate that the Sc and Zn dual-substitution decreases the diffusion barrier of Na-ions and improves the conductivity of the material.The dual-substituted NaMn_(0.5)Ni_(0.4)Sc_(0.04)Zn_(0.04)O_(2)(Na MNSZ44)cathode delivers impressive cycle stability with capacity retention of 71.2%after 200 cycles at 1C and 54.8%after 400 cycles at 5C.Additionally,the full cell paired with hard carbon anode exhibits a remarkable long-term cycling stability,showing capacity retention of 64.1%after 250 cycles at 1C.These results demonstrate that Sc and Zn dual-substitution is an effective strategy to improve the Na^(+) diffusion dynamics and structural stability of NaMN.展开更多
The structural stability, elastic and electronic properties under pressure at 0 K for β-Ti have been investigated by per-forming first-principles calculations. With the increase of pressure, the structure of β-Ti b...The structural stability, elastic and electronic properties under pressure at 0 K for β-Ti have been investigated by per-forming first-principles calculations. With the increase of pressure, the structure of β-Ti becomes stabler, which is further con-firmed by the calculation for density of state （DOS）. The phase transition pressure of is about 64. 3 GPa, which is consist-ent with other theoretical predictions （63. 7 GPa） and the experimental result （50 GPa）. The pressure dependence of elastic constants shows that the low-pressure limit for a mechanically stable β-Ti is about 50 GPa with low Young？s modulus value of about 30. 01 GPa, which approaches the value of a human bone （30 GPa）. In addition, the pressure dependence of bulk modu-lus B, shear modulus G, Young’s modulus E,Poisson’s ratio σ,aggregate sound velocities,and ductility/brittleness under different pressures were also discussed. B, G and E ascend monotonously with increasing pressure, while a descends. β-Ti re-mains ductile by analysis of B/G under considered pressures.展开更多
The metal ion batteries have gained widespread attention for wearable electronics due to their competitive energy density and long cycling life.Exploring the advanced anode materials is significant for next generation...The metal ion batteries have gained widespread attention for wearable electronics due to their competitive energy density and long cycling life.Exploring the advanced anode materials is significant for next generation energy storage systems.However,severe electrode volume changes and sluggish redox kinetics are the critical problems for lithium/potassium ion batteries(LIBs/PIBs)towards large-scale applications.Herein,we prepare a novel anode material,which consists of reduced graphene oxide wrapping one-dimensional(1D)N-doped porous carbon nanotube with cobalt phosphoselenide(CoPSe)nanoparticles embedded inside them(r GO@Co PSe/NC).Benefited from the dual carbon decorations and ultrafine nanoparticles structure,it achieves a reversible capacity of 245 mAh/g at 5 A/g after 2000 cycles for LIBs and 215 mAh/g at 1 A/g after 500 cycles for PIBs.The pseudocapacitance and GITT measurements are used to investigate the electrochemical kinetics of r GO@Co PSe/NC for LIBs.In addition,the lithium ion full cell also shows good electrochemical performance when paired with high capacity LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) cathode.This work provides a feasible electrode design strategy for high-efficiency metal ion batteries based on multidimensional nanoarchitecture engineering and composition tailoring.展开更多
The implementation of ultrahigh-Ni cathodes in high-energy lithium-ion batteries(LIBs)is constrained by significant structural and interfacial degradation during cycling.In this study,doping-induced surface restructur...The implementation of ultrahigh-Ni cathodes in high-energy lithium-ion batteries(LIBs)is constrained by significant structural and interfacial degradation during cycling.In this study,doping-induced surface restructuring in ultrahigh-nickel cathode materials is rapidly facilitated through an ultrafast Joule heating method.Density functional theory(DFT)calculations,synchrotron X-ray absorption spectroscopy(XAS),and single-particle force test confirmed the establishment of a stable crystal framework and lattice oxygen,which mitigated H2-H3 phase transitions and improved structural reversibility.Additionally,the Sc doping process exhibits a pinning effect on the grain boundaries,as shown by scanning transmission electron microscopy(STEM),enhancing Li~+diffusion kinetics and decreasing mechanical strain during cycling.The in situ development of a cation-mixing layer at grain boundaries also creates a robust cathode/electrolyte interphase,effectively reducing interfacial parasitic reactions and transition metal dissolution,as validated by STEM and time-of-flight secondary ion mass spectrometry(TOF-SIMS).These synergistic modifications reduce particle cracking and surface/interface degradation,leading to enhanced rate capability,structural integrity,and thermal stability.Consequently,the optimized Sc-modified ultrahigh-Ni cathode(Sc-1)exhibits 93.99%capacity retention after 100 cycles at 1 C(25℃)and87.06%capacity retention after 100 cycles at 1 C(50℃),indicating excellent cycling and thermal stability.By presenting a one-step multifunctional modification approach,this research delivers an extensive analysis of the mechanisms governing the structure,microstructure,and interface properties of nickel-rich layered cathode materials(NCMs).These results underscore the potential of ultrahigh-Ni cathodes as viable candidates for advanced lithium-ion batteries(LIBs)in next-generation electric vehicles(EVs).展开更多
Silicon-based materials are considered as the next generation anode to replace graphite due to their low cost and ultra-high theoretical capacity.However,significant volume expansion and contraction occur during charg...Silicon-based materials are considered as the next generation anode to replace graphite due to their low cost and ultra-high theoretical capacity.However,significant volume expansion and contraction occur during charging and discharging processes,leading to the instability of electrode structure and susceptibility to peeling and damage,limiting its application.Constructing controllable molecular artificial solid electrolyte interphase(CMASEI)is an effective approach to address the commercialization of silicon-based anode materials[1].Improving the performance of silicon-based anodes through CMASEI is a multifaceted outcome.展开更多
Defect engineering improves the catalytic performance of metal-organic frameworks(MOFs)loaded metal nanoparticles(MNPs@MOFs),but there is still a challenge in defining the structure-activity relationships.Herein,the c...Defect engineering improves the catalytic performance of metal-organic frameworks(MOFs)loaded metal nanoparticles(MNPs@MOFs),but there is still a challenge in defining the structure-activity relationships.Herein,the content of linker-missing defects in UiO-66(Ce)was systematically regulated via formic acid as the modulators,and defective UiO-66(Ce)loaded Ni nanoparticles(NPs)were constructed for dicyclopentadiene(DCPD)hydrogenation.The fine regulation of defect engineering and reduction conditions affected the structure properties of UiO-66(Ce)and the electronic metal-support interaction between MOFs and Ni NPs,thereby optimizing the microenvironment and electronic state of Ni NPs.The optimized U(Ce)-40eq with suitable defects,small size and structure stability effectively promoted the production of highly dispersed abundant electron-deficient Ni^(0) active sites,enhancing the adsorption and activation of H_(2) and C=C bonds,especially accelerating the rate-determining step.Therefore,U(Ce)-40eq loaded 5 wt%Ni NPs achieved DCPD saturated hydrogenation to tetrahydrodicyclopentadiene(70℃,2 MPa,90 min),superior to most high-loading Ni-based catalysts.This work reveals the synergistic mechanism of MOFs defect engineering and electronic structure of Ni NPs,providing effective guidance for the precise preparation of highly efficient and stable MNPs@MOFs heterogeneous catalysts.展开更多
Constructing silicon(Si)-based composite electrodes that possess high energy density,long cycle life,and fast charging capability simultaneously is critical for the development of high performance lithium-ion batterie...Constructing silicon(Si)-based composite electrodes that possess high energy density,long cycle life,and fast charging capability simultaneously is critical for the development of high performance lithium-ion batteries for mitigating range anxiety and slow charging issues in new energy vehicles.Herein,a thick silicon/carbon composite electrode with vertically aligned channels in the thickness direction(VC-SC)is constructed by employing a bubble formation method.Both experimental characterizations and theoretical simulations confirm that the obtained vertical channel structure can effectively address the problem of sluggish ion transport caused by high tortuosity in conventional thick electrodes,conspicuously enhance reaction kinetics,reduce polarization and side reactions,mitigate stress,increase the utilization of active materials,and promote cycling stability of the thick electrode.Consequently,when paired with LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(NCM622),the VC-SC||NCM622 pouch type full cell(~6.0 mAh cm^(-2))exhibits significantly improved rate performance and capacity retention compared with the SC||NCM622 full cell with the conventional silicon/carbon composite electrode without channels(SC)as the anode.The assembled VC-SC||NCM622 pouch full cell with a high energy density of 490.3 Wh kg^(-1)also reveals a remarkable fast charging capability at a high current density of 2.0 mA cm^(-2),with a capacity retention of 72.0%after 500 cycles.展开更多
With the acceleration of urbanization,prefabricated bridges have become a significant choice for transportation infrastructure construction due to their environmental friendliness,efficiency,and reliable quality.Howev...With the acceleration of urbanization,prefabricated bridges have become a significant choice for transportation infrastructure construction due to their environmental friendliness,efficiency,and reliable quality.However,existing connection technologies still face shortcomings in construction efficiency,seismic performance,and cost control.This paper summarizes the process characteristics of commonly used connection technologies such as socket connections,grouted sleeve connections and corrugated pipe connections,and analyzes their seismic capacity and mechanical performance.In response to existing issues,two new technologies—separated steel connection and multi-chamber steel tube concrete connection—are proposed,and their comprehensive performance and economic efficiency are analyzed.The new connection technologies outperform traditional methods in construction efficiency,economic efficiency,and structural stability,with more reasonable force distribution,clearer load transfer paths,and significantly reduced overall costs.Existing technologies,such as socket connections,perform well in seismic performance but are complex to construct;grouted sleeve connections are mature in technology,but the quality of grouting is difficult to inspect.The separated steel connection and multi-chamber steel tube concrete connection technologies offer significant advantages.With the increasing demands for energy conservation and emission reduction,coupled with the rising labor costs,prefabricated bridge piers are undoubtedly poised to become one of the preferred technologies for bridge construction in China in the future.Therefore,in light of the current research landscape,this paper concludes by offering a forward-looking perspective on the development directions of connection methods for prefabricated bridge piers and identifying key areas for future research.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
The unique oxygen stacking sequence of O2-type structures restricts the irreversible transition metal movement into Li vacancies for the delithiated Li-rich layered oxides(LLOs)and maintains outstanding voltage stabil...The unique oxygen stacking sequence of O2-type structures restricts the irreversible transition metal movement into Li vacancies for the delithiated Li-rich layered oxides(LLOs)and maintains outstanding voltage stability.However,the ion-exchange synthesis promotes the Mn-ion valence reduction and aggravates the Jahn-Teller(J-T)distortion alongside disproportionation.Since the main oxidation state of the Mn ions is+4 in the traditional O3-type LLOs,synergistic effects of the O2-type and O3-type structures are expected in the O2/O3 diphasic Li-rich material.Herein,O2/O3 biphasic intergrowth LLOs were rationally designed,and the synergic optimization of the biphasic structure was planned to retard the J-T effect.The O2/O3 intergrowth nature was confirmed,and the percentages of the O2 and O3 phases were 56%and 44%,respectively.Density functional theory calculations demonstrated that the Mn^(2+)(EC)sheath had a remarkably lower energy barrier than the Li^(+)(EC)sheath.This finding suggests that Mn^(2+)ions that are dissolved into the electrolyte accelerate the electrolyte oxidization,so the deposition of the cathode electrolyte interface for pristine O2-LLOs causes a high electrochemical impedance.The designed O2/O3 biphasic LLOs boost the capacity stability and suppress the voltage drop upon repeated Li^(+)de-intercalation.The phase regulation strategy offers great potential for developing low-cost LLOs with enhanced structural stability for advanced Li-ion batteries.展开更多
In pursuit of low cost and long life for lithium-ion batteries in electric vehicles,the most promising strategy is to replace the commercial LiCoO_(2)with a high-energy-density Ni-rich cathode.However,the irreversible...In pursuit of low cost and long life for lithium-ion batteries in electric vehicles,the most promising strategy is to replace the commercial LiCoO_(2)with a high-energy-density Ni-rich cathode.However,the irreversible redox couples induce rapid capacity decay,poor long-term cycling life,vast gas evolution,and unstable structure transformations of the Ni-rich cathode,limiting its practical applications.Element doping has been considered as the most promising strategy for addressing these issues.However,the relationships between element doping functions and redox chemistry still remain confused.To clarify this connection,this review places the dynamic evolution of redox couples(Li^(*),Ni^(2+)/Ni^(3+)/Ni^(4+)-e^(-),O^(2-)/O^(n-)/O_(2)-e^(-))as the tree trunk.The material structure,degradation mechanisms,and addressing element doping strategies are considered as the tree branches.This comprehensive summary aims to provide an overview of the current understanding and progress of Ni-rich cathode materials.In the last section,promising strategies based on element doping functions are provided to encourage the practical application of Ni-rich cathodes.These strategies also offer a new approach for the development of other intercalated electrode materials in Na and K-based battery systems.展开更多
Covalent organic frameworks(COFs)are two-(2D)or threedimensional(3D)crystalline,porous networks generated by reversible polymerization of organic building blocks[1,2].The structures and functionalities of COFs are pre...Covalent organic frameworks(COFs)are two-(2D)or threedimensional(3D)crystalline,porous networks generated by reversible polymerization of organic building blocks[1,2].The structures and functionalities of COFs are precisely controlled via appropriately selected organic building blocks.This design imparts unique properties to COFs,including exceptional structural stability,tunable pore structure,and surface chemical activity,making them promising for gas separation,catalysis,optoelectronics,and sensing applications.Since Yaghi et al.'s seminal report on COFs in 2005[2],these frameworks have swiftly emerged as a hotspot in the field of materials.Originally,the focus was on fabricating rigid frameworks with static structures and optoelectronic properties.However,the inherently static nature of these frameworks hinders their responsiveness to external stimuli,potentially constraining their functionality in specific applications.Hence,an increasing number of researchers are now directing their attention toward the development of dynamic COFs capable of modifying their structures in response to external stimuli[3].Specifically,dynamic 2D COFs exhibiting enhanced structural responsiveness are of particular interest due to their capability to integrate switchable geometries and porosities with semiconductor building blocks,as well as electron conjugation across COF layers and π-stacked columns,which may enable stimuli-responsive electronic and spin properties[4].展开更多
A longstanding discrepancy between theoretical predictions and experimental observations on the highpressurestructural transformations of lanthanum mononitride(LaN)has posed challenges for understandingthe behavior of...A longstanding discrepancy between theoretical predictions and experimental observations on the highpressurestructural transformations of lanthanum mononitride(LaN)has posed challenges for understandingthe behavior of heavy transition metal mononitrides.Here,we systematically investigate the structural evolutionof LaN under high pressure using first-principles calculations combined with angle-dispersive synchrotron X-raydiffraction,identifying the phase transition sequence and corresponding phase boundaries.Analyses of energetics,kinetic barriers,and lattice dynamics reveal distinct mechanisms driving these transitions.These results clarifythe structural stability of LaN and offer guidance for studying other heavy transition metal mononitrides withcomplex electronic behavior under extreme conditions.展开更多
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the financial support of the National Natural Science Foundation of China(NSFC,No.12074093)。
文摘This study presents a novel approach to enhance silicon anode performance through barium titanate(BTO)incorporation,with the establishment of a force-electric coupling model.By introducing piezoelectric BTO into silicon matrices,we successfully improved both the mechanical stability and electrochemical kinetics of the anode.The developed force-electric coupling model explains how BTO mitigates stress accumulation during lithiation while optimizing the kinetics of Li^(+)and electron transfer.Experimental verification and multiphysical simulation indicate that Si@BTO effectively eliminates structural degradation during the cycling process and significantly reduces the charge transfer resistance.The force-electric coupling mechanism further facilitates stable solid electrolyte interphase(SEI)formation.When paired with LiFePO_(4)cathodes,Si@BTO maintains 76% capacity retention after 500 cycles at a 10 C rate.This work establishes a basic force-electric coupling model framework and offers insights into the development of advanced silicon anode batteries with exceptional performance.
基金supported by the National Natural Science Foundation of China(22179008)support from the Beijing Nova Program(20230484241)+1 种基金support from the China Postdoctoral Science Foundation(2024M754084)the Postdoctoral Fellowship Program of CPSF(GZB20230931)。
文摘The rapid expansion of the automotive sector has significantly increased the demand for highperformance lithium-ion batteries,positioning Ni-rich layered cathodes as a promising solution due to their high energy density and cost-efficiency.However,these cathodes face critical challenges,including thermal instability and structural degradation at an elevated temperature,which hinder their practical application.This study introduces an advanced surface reconstruction strategy combining a LiScF_(4)coating,Sc/F surface co-doping,and a cation-mixing layer to address these issues.The LiScF_(4)coating serves as a durable protective barrier,reducing electrolyte decomposition,minimizing transition metal dissolution,and enhancing lithium-ion transport.Sc/F surface co-doping stabilizes lattice oxygen by increasing the energy barrier for oxygen vacancy formation and minimizing oxygen release,thereby suppressing phase transitions and interfacial side reactions.Additionally,the cation-mixing layer improves interfacial stability by alleviating lattice strain and supporting reversible cation migration,ensuring prolonged durability during cycling and under high-temperature conditions.These integrated modifications work synergistically to mitigate various degradation mechanisms,significantly improving the thermal stability,structural integrity,and electrochemical performance of Ni-rich cathodes.This approach offers a viable pathway for incorporating Ni-rich cathodes into advanced lithium-ion batteries,making them well-suited for applications requiring high thermal stability.Moreover,this research provides valuable guidance for the development of a multi-component modification strategy,paving the way for future innovations in energy storage materials and advancing high-performance battery technology.
基金the National Natural Science Foun-dation of China(Grant Nos.52376083 and 51991362).
文摘The heat transfer and stability of methane hydrate in reservoirs have a direct impact on the drilling and production efficiency of hydrate resources,especially in complex stress environments caused by formation subsidence.In this study,we investigated the thermal transport and structural stability of methane hydrate under triaxial compression using molecular dynamics simulations.The results suggest that the thermal conductivity of methane hydrate increases with increasing compression strain.Two phonon transport mechanisms were identified as factors enhancing thermal conductivity.At low compressive strains,a low-frequency phonon transport channel was established due to the overlap of phonon vibration peaks between methane and water molecules.At high compressive strains,the filling of larger phonon bandgaps facilitated the opening of more phonon transport channels.Additionally,we found that a strain of0.04 is a watershed point,where methane hydrate transitions from stable to unstable.Furthermore,a strain of0.06 marks the threshold at which the diffusion capacities of methane and water molecules are at their peaks.At a higher strain of0.08,the increased volume compression reduces the available space,limiting the diffusion ability of water and methane molecules within the hydrate.The synergistic effect of the strong diffusion ability and high probability of collision between atoms increases the thermal conductivity of hydrates during the unstable period compared to the stable period.Our findings offer valuable theoretical insights into the thermal conductivity and stability of methane hydrates in reservoir stress environments.
基金Korea Institute of Materials Science,Grant/Award Number:PNK9370National Research Foundation of Korea,Grant/Award Numbers:NRF-2021R1A2C1014280,NRF-2022R1C1C1011058,NRF-2022M3H446401037201Korea Institute of Science and Technology,Grant/Award Number:2E32581-23-092。
文摘Layered-type transition metal(TM)oxides are considered as one of the most promising cathodes for K-ion batteries because of the large theoretical gravimetric capacity by low molar mass.However,they suffer from severe structural change by de/intercalation and diffusion of K^(+)ions with large ionic size,which results in not only much lower reversible capacity than the theoretical capacity but also poor power capability.Thus,it is important to enhance the structural stability of the layered-type TM oxides for outstanding electrochemical behaviors under the K-ion battery system.Herein,it is investigated that the substitution of the appropriate Ti^(4+)contents enables a highly enlarged reversible capacity of P3-type KxCrO_(2) using combined studies of first-principles calculation and various experiments.Whereas the pristine P3-type KxCrO_(2) just exhibits the reversible capacity of∼120 mAh g^(−1) in the voltage range of 1.5-4.0 V(vs.K^(+)/K),the∼0.61 mol K^(+)corresponding to∼150 mAh g^(−1) can be reversible de/intercalated at the structure of P3-type K0.71[Cr_(0.75)Ti_(0.25)]O_(2) under the same conditions.Furthermore,even at the high current density of 788 mA g^(−1),the specific capacity of P3-type K0.71[Cr_(0.75)Ti_(0.25)]O_(2) is∼120 mAh g^(−1),which is∼81 times larger than that of the pristine P3-type KxCrO_(2).It is believed that this research can provide an effective strategy to improve the electrochemical performances of the cathode materials suffered by severe structural change that occurred during charge/discharge under not only K-ion battery system but also other rechargeable battery systems.
文摘With the increasing spotlight in electric vehicles,there is a growing demand for high-energy-density batteries to enhance driving range.Consequently,several studies have been conducted on high-energy-density LiNi_(x)Co_(y)Mn_(z)O_(2)cathodes.However,there is a limit to permanent performance deterioration because of side reactions caused by moisture in the atmosphere and continuous microcracks during cycling as the Ni content to express high energy increases and the content of Mn and Co that maintain structural and electrochemical stabilization decreases.The direct modification of the surface and bulk regions aims to enhance the capacity and long-term performance of high-Ni cathode materials.Therefore,an efficient modification requires a study based on a thorough understanding of the degradation mechanisms in the surface and bulk region.In this review,a comprehensive analysis of various modifications,including doping,coating,concentration gradient,and single crystals,is conducted to solve degradation issues along with an analysis of the overall degradation mechanism occurring in high-Ni cathode materials.It also summarizes recent research developments related to the following modifications,aims to provide notable points and directions for post-studies,and provides valuable references for the commercialization of stable high-energy-density cathode materials.
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financial support from the National Natural Science Foundation of China(No.52377220)the Natural Science Foundation of Hunan Province,China(No.kq2208265)。
文摘Sc and Zn were introduced into O3-NaMn_(0.5)Ni_(0.5)O_(2)(NaMN)using the combination of solution combustion and solid-state method.The effect of Sc and Zn dual-substitution on Na^(+) diffusion dynamics and structural stability of NaMN was investigated.The physicochemical characterizations suggest that the introduction of Sc and Zn broaden Na^(+) diffusion channels and weaken the Na—O bonds,thereby facilitating the diffusion of sodium ions.Simulations indicate that the Sc and Zn dual-substitution decreases the diffusion barrier of Na-ions and improves the conductivity of the material.The dual-substituted NaMn_(0.5)Ni_(0.4)Sc_(0.04)Zn_(0.04)O_(2)(Na MNSZ44)cathode delivers impressive cycle stability with capacity retention of 71.2%after 200 cycles at 1C and 54.8%after 400 cycles at 5C.Additionally,the full cell paired with hard carbon anode exhibits a remarkable long-term cycling stability,showing capacity retention of 64.1%after 250 cycles at 1C.These results demonstrate that Sc and Zn dual-substitution is an effective strategy to improve the Na^(+) diffusion dynamics and structural stability of NaMN.
基金International Cooperation Project of the Ministry of Science and Technology of China(No.2014DFA50320)National Natural Science Foundation of China(Nos.51674226,51574207,51574206,51274175)+1 种基金International Science and Technology Cooperation Project of Shanxi Province(No.2015081041)Research Project Supported by Shanxi Scholarship Council of China(No.2016-Key 2)
文摘The structural stability, elastic and electronic properties under pressure at 0 K for β-Ti have been investigated by per-forming first-principles calculations. With the increase of pressure, the structure of β-Ti becomes stabler, which is further con-firmed by the calculation for density of state （DOS）. The phase transition pressure of is about 64. 3 GPa, which is consist-ent with other theoretical predictions （63. 7 GPa） and the experimental result （50 GPa）. The pressure dependence of elastic constants shows that the low-pressure limit for a mechanically stable β-Ti is about 50 GPa with low Young？s modulus value of about 30. 01 GPa, which approaches the value of a human bone （30 GPa）. In addition, the pressure dependence of bulk modu-lus B, shear modulus G, Young’s modulus E,Poisson’s ratio σ,aggregate sound velocities,and ductility/brittleness under different pressures were also discussed. B, G and E ascend monotonously with increasing pressure, while a descends. β-Ti re-mains ductile by analysis of B/G under considered pressures.
基金financially supported by the National Natural Science Foundation of China(No.22204028)Young Talent Support Project of Guangzhou Association for Science and Technology(No.QT-2023-003)+3 种基金Guangdong Basic and Applied Basic Research Fund Project(No.2022A1515110451)Guangzhou University Graduate Student Innovation Ability Cultivation Funding Program(No.2022GDJC-M06)Science and Technology Projects in Guangzhou(Nos.202201010245,2023A03J0029)Double-Thousand Talents Plan of Jiangxi Province(No.jxsq2023102005)。
文摘The metal ion batteries have gained widespread attention for wearable electronics due to their competitive energy density and long cycling life.Exploring the advanced anode materials is significant for next generation energy storage systems.However,severe electrode volume changes and sluggish redox kinetics are the critical problems for lithium/potassium ion batteries(LIBs/PIBs)towards large-scale applications.Herein,we prepare a novel anode material,which consists of reduced graphene oxide wrapping one-dimensional(1D)N-doped porous carbon nanotube with cobalt phosphoselenide(CoPSe)nanoparticles embedded inside them(r GO@Co PSe/NC).Benefited from the dual carbon decorations and ultrafine nanoparticles structure,it achieves a reversible capacity of 245 mAh/g at 5 A/g after 2000 cycles for LIBs and 215 mAh/g at 1 A/g after 500 cycles for PIBs.The pseudocapacitance and GITT measurements are used to investigate the electrochemical kinetics of r GO@Co PSe/NC for LIBs.In addition,the lithium ion full cell also shows good electrochemical performance when paired with high capacity LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) cathode.This work provides a feasible electrode design strategy for high-efficiency metal ion batteries based on multidimensional nanoarchitecture engineering and composition tailoring.
基金supported by the National Key R&D Program of China(2022YFB3803501)the National Natural Science Foundation of China(22179008,22209156)+5 种基金support from the Beijing Nova Program(20230484241)support from the China Postdoctoral Science Foundation(2024M754084)the Postdoctoral Fellowship Program of CPSF(GZB20230931)support from beamline BL08U1A of Shanghai Synchrotron Radiation Facility(2024-SSRF-PT-506950)beamline 1W1B of the Beijing Synchrotron Radiation Facility(2021-BEPC-PT-006276)support from Initial Energy Science&Technology Co.,Ltd(IEST)。
文摘The implementation of ultrahigh-Ni cathodes in high-energy lithium-ion batteries(LIBs)is constrained by significant structural and interfacial degradation during cycling.In this study,doping-induced surface restructuring in ultrahigh-nickel cathode materials is rapidly facilitated through an ultrafast Joule heating method.Density functional theory(DFT)calculations,synchrotron X-ray absorption spectroscopy(XAS),and single-particle force test confirmed the establishment of a stable crystal framework and lattice oxygen,which mitigated H2-H3 phase transitions and improved structural reversibility.Additionally,the Sc doping process exhibits a pinning effect on the grain boundaries,as shown by scanning transmission electron microscopy(STEM),enhancing Li~+diffusion kinetics and decreasing mechanical strain during cycling.The in situ development of a cation-mixing layer at grain boundaries also creates a robust cathode/electrolyte interphase,effectively reducing interfacial parasitic reactions and transition metal dissolution,as validated by STEM and time-of-flight secondary ion mass spectrometry(TOF-SIMS).These synergistic modifications reduce particle cracking and surface/interface degradation,leading to enhanced rate capability,structural integrity,and thermal stability.Consequently,the optimized Sc-modified ultrahigh-Ni cathode(Sc-1)exhibits 93.99%capacity retention after 100 cycles at 1 C(25℃)and87.06%capacity retention after 100 cycles at 1 C(50℃),indicating excellent cycling and thermal stability.By presenting a one-step multifunctional modification approach,this research delivers an extensive analysis of the mechanisms governing the structure,microstructure,and interface properties of nickel-rich layered cathode materials(NCMs).These results underscore the potential of ultrahigh-Ni cathodes as viable candidates for advanced lithium-ion batteries(LIBs)in next-generation electric vehicles(EVs).
基金supported by the Nanxun Scholars Program for Young Scholars of ZJWEU(No.RC2023021315)the start-up funding for Scientific Research for High-level Talents(No.88106324004)the National Natural Science Foundation of China(No.62304070).
文摘Silicon-based materials are considered as the next generation anode to replace graphite due to their low cost and ultra-high theoretical capacity.However,significant volume expansion and contraction occur during charging and discharging processes,leading to the instability of electrode structure and susceptibility to peeling and damage,limiting its application.Constructing controllable molecular artificial solid electrolyte interphase(CMASEI)is an effective approach to address the commercialization of silicon-based anode materials[1].Improving the performance of silicon-based anodes through CMASEI is a multifaceted outcome.
文摘Defect engineering improves the catalytic performance of metal-organic frameworks(MOFs)loaded metal nanoparticles(MNPs@MOFs),but there is still a challenge in defining the structure-activity relationships.Herein,the content of linker-missing defects in UiO-66(Ce)was systematically regulated via formic acid as the modulators,and defective UiO-66(Ce)loaded Ni nanoparticles(NPs)were constructed for dicyclopentadiene(DCPD)hydrogenation.The fine regulation of defect engineering and reduction conditions affected the structure properties of UiO-66(Ce)and the electronic metal-support interaction between MOFs and Ni NPs,thereby optimizing the microenvironment and electronic state of Ni NPs.The optimized U(Ce)-40eq with suitable defects,small size and structure stability effectively promoted the production of highly dispersed abundant electron-deficient Ni^(0) active sites,enhancing the adsorption and activation of H_(2) and C=C bonds,especially accelerating the rate-determining step.Therefore,U(Ce)-40eq loaded 5 wt%Ni NPs achieved DCPD saturated hydrogenation to tetrahydrodicyclopentadiene(70℃,2 MPa,90 min),superior to most high-loading Ni-based catalysts.This work reveals the synergistic mechanism of MOFs defect engineering and electronic structure of Ni NPs,providing effective guidance for the precise preparation of highly efficient and stable MNPs@MOFs heterogeneous catalysts.
基金National Key R&D Program of China,Grant/Award Number:2023YFB2503900National Natural Science Foundation of China,Grant/Award Number:12172143Shenzhen Science and Technology Program,Grant/Award Numbers:JCYJ20220818100418040,JCYJ20220530160816038。
文摘Constructing silicon(Si)-based composite electrodes that possess high energy density,long cycle life,and fast charging capability simultaneously is critical for the development of high performance lithium-ion batteries for mitigating range anxiety and slow charging issues in new energy vehicles.Herein,a thick silicon/carbon composite electrode with vertically aligned channels in the thickness direction(VC-SC)is constructed by employing a bubble formation method.Both experimental characterizations and theoretical simulations confirm that the obtained vertical channel structure can effectively address the problem of sluggish ion transport caused by high tortuosity in conventional thick electrodes,conspicuously enhance reaction kinetics,reduce polarization and side reactions,mitigate stress,increase the utilization of active materials,and promote cycling stability of the thick electrode.Consequently,when paired with LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(NCM622),the VC-SC||NCM622 pouch type full cell(~6.0 mAh cm^(-2))exhibits significantly improved rate performance and capacity retention compared with the SC||NCM622 full cell with the conventional silicon/carbon composite electrode without channels(SC)as the anode.The assembled VC-SC||NCM622 pouch full cell with a high energy density of 490.3 Wh kg^(-1)also reveals a remarkable fast charging capability at a high current density of 2.0 mA cm^(-2),with a capacity retention of 72.0%after 500 cycles.
基金supported by Prevention the Fundamental Research Funds for the Central Universities“Study on the general joint of prefabricated high-pier columns”(ZY20230218)Science and Technology Innovation Program for Postgraduate students in IDP subsidized by Fundamental Research Funds for the Central Universities“Research on seismic performance of prefabricated bridge piers with embedded separated steel connections”(ZY20250316).
文摘With the acceleration of urbanization,prefabricated bridges have become a significant choice for transportation infrastructure construction due to their environmental friendliness,efficiency,and reliable quality.However,existing connection technologies still face shortcomings in construction efficiency,seismic performance,and cost control.This paper summarizes the process characteristics of commonly used connection technologies such as socket connections,grouted sleeve connections and corrugated pipe connections,and analyzes their seismic capacity and mechanical performance.In response to existing issues,two new technologies—separated steel connection and multi-chamber steel tube concrete connection—are proposed,and their comprehensive performance and economic efficiency are analyzed.The new connection technologies outperform traditional methods in construction efficiency,economic efficiency,and structural stability,with more reasonable force distribution,clearer load transfer paths,and significantly reduced overall costs.Existing technologies,such as socket connections,perform well in seismic performance but are complex to construct;grouted sleeve connections are mature in technology,but the quality of grouting is difficult to inspect.The separated steel connection and multi-chamber steel tube concrete connection technologies offer significant advantages.With the increasing demands for energy conservation and emission reduction,coupled with the rising labor costs,prefabricated bridge piers are undoubtedly poised to become one of the preferred technologies for bridge construction in China in the future.Therefore,in light of the current research landscape,this paper concludes by offering a forward-looking perspective on the development directions of connection methods for prefabricated bridge piers and identifying key areas for future research.
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.
基金supported by the National Natural Science Foundation of China(Nos.22379052,22479062 and 52102252)Taishan Scholars of Shandong Province(No.tsqnz20221143)Independent Cultivation Program of Innovation Team of Ji’nan City(No.202333042).
文摘The unique oxygen stacking sequence of O2-type structures restricts the irreversible transition metal movement into Li vacancies for the delithiated Li-rich layered oxides(LLOs)and maintains outstanding voltage stability.However,the ion-exchange synthesis promotes the Mn-ion valence reduction and aggravates the Jahn-Teller(J-T)distortion alongside disproportionation.Since the main oxidation state of the Mn ions is+4 in the traditional O3-type LLOs,synergistic effects of the O2-type and O3-type structures are expected in the O2/O3 diphasic Li-rich material.Herein,O2/O3 biphasic intergrowth LLOs were rationally designed,and the synergic optimization of the biphasic structure was planned to retard the J-T effect.The O2/O3 intergrowth nature was confirmed,and the percentages of the O2 and O3 phases were 56%and 44%,respectively.Density functional theory calculations demonstrated that the Mn^(2+)(EC)sheath had a remarkably lower energy barrier than the Li^(+)(EC)sheath.This finding suggests that Mn^(2+)ions that are dissolved into the electrolyte accelerate the electrolyte oxidization,so the deposition of the cathode electrolyte interface for pristine O2-LLOs causes a high electrochemical impedance.The designed O2/O3 biphasic LLOs boost the capacity stability and suppress the voltage drop upon repeated Li^(+)de-intercalation.The phase regulation strategy offers great potential for developing low-cost LLOs with enhanced structural stability for advanced Li-ion batteries.
基金supported by the National Natural Science Foundation of China(22209055)the China Postdoctoral Science Foundation(2022M721330)+2 种基金the Foshan Postdoctoral Science Foundation(X221081MS210)the Innovation Team of Universities of Guangdong Province(2022KCXTD030)the“Targeted Technology Innovation Initiative”Project at the Foshan National Institute of Innovation(JBGS2024002)。
文摘In pursuit of low cost and long life for lithium-ion batteries in electric vehicles,the most promising strategy is to replace the commercial LiCoO_(2)with a high-energy-density Ni-rich cathode.However,the irreversible redox couples induce rapid capacity decay,poor long-term cycling life,vast gas evolution,and unstable structure transformations of the Ni-rich cathode,limiting its practical applications.Element doping has been considered as the most promising strategy for addressing these issues.However,the relationships between element doping functions and redox chemistry still remain confused.To clarify this connection,this review places the dynamic evolution of redox couples(Li^(*),Ni^(2+)/Ni^(3+)/Ni^(4+)-e^(-),O^(2-)/O^(n-)/O_(2)-e^(-))as the tree trunk.The material structure,degradation mechanisms,and addressing element doping strategies are considered as the tree branches.This comprehensive summary aims to provide an overview of the current understanding and progress of Ni-rich cathode materials.In the last section,promising strategies based on element doping functions are provided to encourage the practical application of Ni-rich cathodes.These strategies also offer a new approach for the development of other intercalated electrode materials in Na and K-based battery systems.
基金supported by the National Natural Science Foundation of China(Nos.51902121 and 22372067)。
文摘Covalent organic frameworks(COFs)are two-(2D)or threedimensional(3D)crystalline,porous networks generated by reversible polymerization of organic building blocks[1,2].The structures and functionalities of COFs are precisely controlled via appropriately selected organic building blocks.This design imparts unique properties to COFs,including exceptional structural stability,tunable pore structure,and surface chemical activity,making them promising for gas separation,catalysis,optoelectronics,and sensing applications.Since Yaghi et al.'s seminal report on COFs in 2005[2],these frameworks have swiftly emerged as a hotspot in the field of materials.Originally,the focus was on fabricating rigid frameworks with static structures and optoelectronic properties.However,the inherently static nature of these frameworks hinders their responsiveness to external stimuli,potentially constraining their functionality in specific applications.Hence,an increasing number of researchers are now directing their attention toward the development of dynamic COFs capable of modifying their structures in response to external stimuli[3].Specifically,dynamic 2D COFs exhibiting enhanced structural responsiveness are of particular interest due to their capability to integrate switchable geometries and porosities with semiconductor building blocks,as well as electron conjugation across COF layers and π-stacked columns,which may enable stimuli-responsive electronic and spin properties[4].
基金supported by the Natural Science Foundation of China(Grant Nos.T2325013,12474004,and 52288102)the National Key Research and Development Program of China(Grant No.2021YFA1400503)the Program for Jilin University Science and Technology Innovative Research Team。
文摘A longstanding discrepancy between theoretical predictions and experimental observations on the highpressurestructural transformations of lanthanum mononitride(LaN)has posed challenges for understandingthe behavior of heavy transition metal mononitrides.Here,we systematically investigate the structural evolutionof LaN under high pressure using first-principles calculations combined with angle-dispersive synchrotron X-raydiffraction,identifying the phase transition sequence and corresponding phase boundaries.Analyses of energetics,kinetic barriers,and lattice dynamics reveal distinct mechanisms driving these transitions.These results clarifythe structural stability of LaN and offer guidance for studying other heavy transition metal mononitrides withcomplex electronic behavior under extreme conditions.
