Layered double hydroxides(LDHs)are promising electrocatalysts for the oxygen evolution reaction(OER),yet their practical application remains limited by poor electrical conductivity and sluggish reaction kinetics.In th...Layered double hydroxides(LDHs)are promising electrocatalysts for the oxygen evolution reaction(OER),yet their practical application remains limited by poor electrical conductivity and sluggish reaction kinetics.In this work,we synthesize three high-entropy LDHs(HELDHs)featuring a hierarchical architecture of microspheres assembled from ultrathin nanosheets,via a simple hydrothermal method using a combination of low-cost,catalytically active transition metals(Fe,Co,Ni,Mn,Zn,Cu,and Cr).Among them,the FeCoNiMnZn HELDH exhibits outstanding OER performance,requiring an overpotential of only 306 mV to reach a current density of 100 mA cm^(-2).Notably,during 200 h of continuous operation,the device exhibits a stable and,in some cases,increasing current output.This exceptional activity is attributed to the formation of abundant cation vacancies,induced by Zn leaching,which enhance the intrinsic catalytic properties by optimizing the adsorption energies of key OER intermediates.Density functional theory calculations further validate that these vacancies modulate the electronic structure and lower reaction barriers,underscoring the effectiveness of cation-vacancy engineering in high-entropy systems for efficient and durable water oxidation catalysis.The optimized catalyst was further evaluated as the air cathode in a zinc-air battery,demonstrating practical electrochemical performance.展开更多
Layered transition metal oxide cathode materials have garnered increasing attention for sodium-ion batteries(SIBs).However,they are plagued by the Jahn-Teller distortion of MnO6,Na^(+)/vacancy ordering,and irreversibl...Layered transition metal oxide cathode materials have garnered increasing attention for sodium-ion batteries(SIBs).However,they are plagued by the Jahn-Teller distortion of MnO6,Na^(+)/vacancy ordering,and irreversible lattice oxygen loss,which collectively lead to capacity fading and voltage decay.Herein,we report a P2-type material,Na_(0.67)Ni_(0.3)Mn_(0.6)Li_(0.09)Sn_(0.01)O_(2)(NNMO-Li0.09Sn0.01),modified with two closed-shell dopants(i.e.,Li^(+)and Sn^(4+)).Benefiting from the unique electronic configurations of closed-shell ions,NNMO-Li0.09Sn0.01 exhibits enhanced structural and electrochemical stability.Specifically,the incorporation of Li^(+)increases the Mn^(4+)/Mn3+ratio,thereby mitigating Jahn-Teller distortion during(de)sodiation process.In addition,Li^(+)disrupts the Ni/Mn ordering in the transition metal layer,suppressing Na^(+)/vacancy ordering.Meanwhile,the introduction of Sn^(4+)forms stronger Sn-O bonds(548 kJ mol-1),thereby enhancing the bonding strength between neighboring transition metal ions and surrounding oxygen atoms,effectively reducing oxygen loss during cycling.NNMO-Li0.09Sn0.01 exhibits significantly improved cycling stability,delivering a specific capacity of 90.3 mAh g^(-1)with 62.9%capacity retention after 50 cycles at 0.1 C(1 C=200 mA g^(-1)),along with 90.3%voltage retention.This substitution strategy based on closed-shell ions offers a viable approach for enhancing the structural stability of wide-voltage layered oxide cathodes.展开更多
O3-types layered cathode materials in sodium-ion batteries(SIBs)suffer from the obvious lattice distortion induced by the complex phase transitions during Na^(+)intercalation/deintercalation process,leading to severe ...O3-types layered cathode materials in sodium-ion batteries(SIBs)suffer from the obvious lattice distortion induced by the complex phase transitions during Na^(+)intercalation/deintercalation process,leading to severe structural collapse and performance degradation.Herein,a series of high valence tantalum(Ta^(5+))doped Na(Ni_(0.4)Fe_(0.2)Mn_(0.4))_(1−x)Ta_(x)O_(2)(x=0/0.0025/0.005/0.01)secondary spherical particles are firstly developed,where Ta^(5+)doping enables the refined primary grain with a tightly stacked rod-like morphology.Comprehensive structural analysis via Neutron powder diffraction(NPD)and Synchrotron radiation X-ray diffraction(SXRD)reveals an expanded NaO_(2)slab and a reduction in Na site vacancy.The potential charge compensation mechanism is further illustrated by X-ray absorption spectroscopy(XAS)and X-ray photoelectron spectroscopy(XPS),unveiling a partial reduction from Ni^(3+)to Ni^(2+)with Ta^(5+)doping.In situ X-ray diffraction(in situ XRD)suggests that the decorated sample undergoes a volume change as low as 0.8%,in contrast with the pristine one(1.5%).Thus,the optimized sample with x=0.005 retains an enhanced capacity retention up to 70.4%at 1 C after 300 cycles in half-cell and delivers a high energy density of 251 Wh kg^(-1)(0.1 C)and with a good capacity retention of 81.0%at 1 C after 200 cycles in full-cell.Our findings provide new insights into the mechanism of high valence Ta^(5+)doping in stabilizing layered oxides cathode materials for SIBs.展开更多
With the continuous development of the offshore wind industry,the design concept of composite foundation has been given attention in the past decade.This paper presents an accurate method for investigating the horizon...With the continuous development of the offshore wind industry,the design concept of composite foundation has been given attention in the past decade.This paper presents an accurate method for investigating the horizontal vibration of monopile-friction wheel composite foundations in layered saturated soil.Firstly,the three-dimensional continuum mechanics theory with the range of linear elasticity is introduced to calculate the frictional resistance distributed on the upper soil surface.Then,the resistances of multilayered soils and inviscid seawater to the pile shaft under horizontal harmonic excitation are obtained using Novak's plane strain model,Biot's porous media theory and radiationwave theory.Thirdly,the expressions for the deformation,bending moment and internal force of the Euler-Bernoulli pile are derived using the boundary conditions with definitephysical meaning and transfer matrix method.By comparing with the results of 1g laboratory test and the idealized formula reported by the literature,the rationality and accuracy of the developed dynamical model can be verified.Finally,this paper conducts a series of worked examples to investigate the influencesof the elastic modulus and thickness of three-layer saturated soil and the location of interlayer soil on the horizontal dynamic vibration of composite foundation.The results show that an increase in elastic modulus of the surface soil is an effective way to improve the dynamic stability of the composite foundation in service conditions.The conclusions drawn from the numerical examples can develop some guidelines for the current foundation design of offshore wind turbines.展开更多
Conventional Tb^(3+)-doped phosphors typically suffer from concentration quenching once the doping level exceeds a critical threshold.Consequently,the development of Tb^(3+)phosphors with intrinsic resistance to conce...Conventional Tb^(3+)-doped phosphors typically suffer from concentration quenching once the doping level exceeds a critical threshold.Consequently,the development of Tb^(3+)phosphors with intrinsic resistance to concentration quenching has become a key research focus.In this work,we successfully synthesized KBi(MoO_(4))_(2):x Tb^(3+)(x=0-100 at%)(denoted as KBM:x Tb^(3+))phosphors via a high-temperature solid-state reaction.Remarkably,no concentration quenching was observed across the entire doping range.This anti-quenching behavior originates from the large Tb^(3+)-Tb^(3+)interionic distance(>5Å)inherent to the quasi-layered crystal structure,which effectively suppresses multipole-interaction-mediated energy migration.At full Tb^(3+)substitution(x=100 at%),the material undergoes a structural phase transition from the monoclinic KBM phase to the triclinicα-KTb(MoO_(4))_(2)(α-KTM)phase.Theα-KTM phosphor exhibits excellent thermal stability(activation energy=0.6129 eV)and a single-exponential decay profile,whereas KBM:x Tb^(3+)(x<100%)display double-exponential decay behaviors,attributed to dual energy transfer pathways.These findings provide new insights into the luminescence mechanisms of high-concentration rare-earth-doped systems and offer guidance for designing nextgeneration anti-quenching phosphors.展开更多
Layered rocks are widely distributed in sedimentary and metamorphic rocks and show anisotropic deformation and strength due to the layered structures with apparent weak surfaces.This study summarizes the findings on t...Layered rocks are widely distributed in sedimentary and metamorphic rocks and show anisotropic deformation and strength due to the layered structures with apparent weak surfaces.This study summarizes the findings on the deformation and damage characteristics of layered rock masses and surrounding rocks.The physicomechanical properties of layered rocks with different properties(e.g.inclination,shear strength,tensile strength,shear stiffness,roughness,and layer spacing)and different lithological and stress conditions are analyzed.The results revealed that with increasing layer inclination angles,the deformation and strength parameters of the rock masses present U-shaped,W-shaped,incremental,decremental,and basically unchanged trends,which are closely related to their strength and stress conditions.The increase in layer strength and confining pressure effectively suppresses the deformation and strength anisotropy caused by layer weakening,and the rock mass shifts from“structure-controlled”to“stress-structure-controlled”deformation mode.Water will increase the anisotropic behavior of layered rock masses due to the degradation of bedding and bedrock performance.The anisotropic behavior of the layered surrounding rocks is analyzed to reveal how it affects the deformation and failure behaviors of tunnels.The asymmetric characteristics of surrounding rock deformation are closely related to the layer weakening,layer thickness,and in situ stress.These findings are crucial for understanding layered rock mass deformation and failure mechanisms,facilitating prediction and control of tunnel deformation.展开更多
The morphological distribution of absorbent in composites is equally important with absorbents for the overall electromagnetic properties,but it is often ignored.Herein,a comprehensive consideration including electrom...The morphological distribution of absorbent in composites is equally important with absorbents for the overall electromagnetic properties,but it is often ignored.Herein,a comprehensive consideration including electromagnetic component regulation,layered arrangement structure,and gradient concentration distribution was used to optimize impedance matching and enhance electromagnetic loss.On the microscale,the incorporation of magnetic Ni nanoparticles into MXene nanosheets(Ni@MXene)endows suitable intrinsic permittivity and permeability.On the macroscale,the layered arrangement of Ni@MXene increases the effective interaction area with electromagnetic waves,inducing multiple reflection/scattering effects.On this basis,according to the analysis of absorption,reflection,and transmission(A-R-T)power coefficients of layered composites,the gradient concentration distribution was constructed to realize the impedance matching at low-concentration surface layer,electromagnetic loss at middle concentration interlayer and microwave reflection at high-concentration bottom layer.Consequently,the layered gradient composite(LG5-10-15)achieves complete absorption coverage of X-band at thickness of 2.00-2.20 mm with RL_(min) of-68.67 dB at 9.85 GHz in 2.05 mm,which is 199.0%,12.6%,and 50.6%higher than non-layered,layered and layered descending gradient composites,respectively.Therefore,this work confirms the importance of layered gradient structure in improving absorption performance and broadens the design of high-performance microwave absorption materials.展开更多
Oxygen release and electrolyte decomposition under high voltage endlessly exacerbate interfacial ramifications and structu ral degradation of high energy-density Li-rich layered oxide(LLO),leading to voltage and capac...Oxygen release and electrolyte decomposition under high voltage endlessly exacerbate interfacial ramifications and structu ral degradation of high energy-density Li-rich layered oxide(LLO),leading to voltage and capacity fading.Herein,the dual-strategy of Cr,B complex coating and local gradient doping is simultaneously achieved on LLO surface by a one-step wet chemical reaction at room temperature.Density functional theory(DFT)calculations prove that stable B-O and Cr-O bonds through the local gradient doping can significantly reduce the high-energy O 2p states of interfacial lattice O,which is also effective for the near-surface lattice O,thus greatly stabilizing the LLO surface,Besides,differential electrochemical mass spectrometry(DEMS)indicates that the Cr_(x)B complex coating can adequately inhibit oxygen release and prevents the migration or dissolution of transition metal ions,including allowing speedy Li^(+)migration,The voltage and capacity fading of the modified cathode(LLO-C_(r)B)are adequately suppressed,which are benefited from the uniformly dense cathode electrolyte interface(CEI)composed of balanced organic/inorganic composition.Therefore,the specific capacity of LLO-CrB after 200 cycles at 1C is 209.3 mA h g^(-1)(with a retention rate of 95.1%).This dual-strategy through a one-step wet chemical reaction is expected to be applied in the design and development of other anionic redox cathode materials.展开更多
Layered transition metal oxides have emerged as promising cathode materials for sodium ion batteries.However,irreversible phase transitions cause structural distortion and cation rearrangement,leading to sluggish Na+d...Layered transition metal oxides have emerged as promising cathode materials for sodium ion batteries.However,irreversible phase transitions cause structural distortion and cation rearrangement,leading to sluggish Na+dynamics and rapid capacity decay.In this study,we propose a medium-entropy cathode by simultaneously introducing Fe,Mg,and Li dopants into a typical P2-type Na_(0.75)Ni_(0.25)Mn_(0.75)O_(2)cathode.The modified Na_(0.75)Ni_(0.2125)Mn_(0.6375)Fe_(0.05)Mg_(0.05)Li_(0.05)O_(2)cathode predominantly exhibits a main P2 phase(93.5%)with a minor O3 phase(6.5%).Through spectroscopy techniques and electrochemical investigations,we elucidate the redox mechanisms of Ni^(2+/3+/4+),Mn^(3+/4+),Fe^(3+/4+),and O_(2)-/O_(2)^(n-)during charging/discharging.The medium-entropy doping mitigates the detrimental P2-O_(2)phase transition at high-voltage,replacing it with a moderate and reversible structural evolution(P2-OP4),thereby enhancing structural stability.Consequently,the modified cathode exhibits a remarkable rate capacity of 108.4 mAh·g^(-1)at 10C,with a capacity retention of 99.0%after 200 cycles at 1C,82.5%after 500 cycles at 5C,and 76.7%after 600 cycles at 10C.Furthermore,it also demonstrates superior electrochemical performance at high cutoff voltage of 4.5 V and extreme temperature(55 and 0℃).This work offers solutions to critical challenges in sodium ion batteries cathode materials.展开更多
The cobalt-free Mn-based Li-rich layered oxide material has the advantages of low cost,high energy density,and good performance at low temperatures,and is the promising choice for energy storage batteries.However,the ...The cobalt-free Mn-based Li-rich layered oxide material has the advantages of low cost,high energy density,and good performance at low temperatures,and is the promising choice for energy storage batteries.However,the long-cycling stability of batteries needs to be improved.Herein,the Mn-based Li-rich cathode materials with small amounts of Li2 MnO3 crystal domains and gradient doping of Al and Ti elements from the surface to the bulk have been developed to improve the structure and interface stability.Then the batteries with a high energy density of 600 Wh kg^(-1),excellent capacity retention of 99.7%with low voltage decay of 0.03 mV cycle^(-1) after 800 cycles,and good rates performances can be achieved.Therefore,the structure and cycling stability of low voltage Mn-based Li-rich cathode materials can be significantly improved by the bulk structure design and interface regulation,and this work has paved the way for developing low-cost and high-energy Mn-based energy storage batteries with long lifetime.展开更多
The umbilical,a key component in offshore energy extraction,plays a vital role in ensuring the stable operation of the entire production system.The extensive variety of cross-sectional components creates highly comple...The umbilical,a key component in offshore energy extraction,plays a vital role in ensuring the stable operation of the entire production system.The extensive variety of cross-sectional components creates highly complex layout combinations.Furthermore,due to constraints in component quantity and geometry within the cross-sectional layout,filler bodies must be incorporated to maintain cross-section performance.Conventional design approaches based on manual experience suffer from inefficiency,high variability,and difficulties in quantification.This paper presents a multi-level automatic filling optimization design method for umbilical cross-sectional layouts to address these limitations.Initially,the research establishes a multi-objective optimization model that considers compactness,balance,and wear resistance of the cross-section,employing an enhanced genetic algorithm to achieve a near-optimal layout.Subsequently,the study implements an image processing-based vacancy detection technique to accurately identify cross-sectional gaps.To manage the variability and diversity of these vacant regions,the research introduces a multi-level filling method that strategically selects and places filler bodies of varying dimensions,overcoming the constraints of uniform-size fillers.Additionally,the method incorporates a hierarchical strategy that subdivides the complex cross-section into multiple layers,enabling layer-by-layer optimization and filling.This approach reduces manufac-turing equipment requirements while ensuring practical production process feasibility.The methodology is validated through a specific umbilical case study.The results demonstrate improvements in compactness,balance,and wear resistance compared with the initial cross-section,offering novel insights and valuable references for filler design in umbilical cross-sections.展开更多
Sodium-ion batteries(SIBs)have attracted significant attention in large-scale energy storage system because of their abundant sodium resource and cost-effectiveness.Layered oxide materials are particularly promising a...Sodium-ion batteries(SIBs)have attracted significant attention in large-scale energy storage system because of their abundant sodium resource and cost-effectiveness.Layered oxide materials are particularly promising as SIBs cathodes due to their high theoretical capacities and facile synthesis.However,their practical applications are hindered by the limitations in energy density and cycling stability.The comprehensive understanding of failure mechanisms within bulk structure and at the cathode/electrolyte interface of cathodes is still lacking.In this review,the issues related to bulk phase degradation and surface degradation,such as irreversible phase transitions,cation migration,transition metal dissolution,air/moisture instability,intergranular cracking,interfacial reactions,and reactive oxygen loss,are discussed.The latest advances and strategies to improve the stability of layered oxide cathodes and full cells are provided,as well as our perspectives on the future development of SIBs.展开更多
Mn-based layered oxides(KMO)have emerged as one of the promising low-cost cathodes for potassiumion batteries(PIBs).However,due to the multiple-phase transitions and the distortion in the MnO6structure induced by the ...Mn-based layered oxides(KMO)have emerged as one of the promising low-cost cathodes for potassiumion batteries(PIBs).However,due to the multiple-phase transitions and the distortion in the MnO6structure induced by the Jahn-Teller(JT)effect associated with Mn-ion,the cathode exhibits poor structural stability.Herein,we propose a strategy to enhance structural stability by introducing robust metal-oxygen(M-O)bonds,which can realize the pinning effect to constrain the distortion in the transition metal(TM)layer.Concurrently,all the elements employed have exceptionally high crustal abundance.As a proof of concept,the designed K_(0.5)Mn_(0.9)Mg_(0.025)Ti_(0.025)Al_(0.05)O_(2)cathode exhibited a discharge capacity of approximately 100 mA h g^(-1)at 20 mA g^(-1)with 79%capacity retention over 50 cycles,and 73%capacity retention over 200 cycles at 200 mA g^(-1),showcased much better battery performance than the designed cathode with less robust M-O bonds.The properties of the formed M-O bonds were investigated using theoretical calculations.The enhanced dynamics,mitigated JT effect,and improved structural stability were elucidated through the in-situ X-ray diffractometer(XRD),in-situ electrochemical impedance spectroscopy(EIS)(and distribution of relaxation times(DRT)method),and ex-situ X-ray absorption fine structure(XAFS)tests.This study holds substantial reference value for the future design of costeffective Mn-based layered cathodes for PIBs.展开更多
Sodium-ion batteries(SIBs)have the advantages of environmental friendliness,cost-effectiveness,and high energy density,which are considered one of the most promising candidates for lithium-ion batteries(LIBs).The cath...Sodium-ion batteries(SIBs)have the advantages of environmental friendliness,cost-effectiveness,and high energy density,which are considered one of the most promising candidates for lithium-ion batteries(LIBs).The cathode materials influence the cost and energy output of SIBs.Therefore,the development of advanced cathode materials is crucial for the practical application of SIBs.Among various cathode materials,layered transition metal oxides(LTMOs)have received widespread attention owing to their straightforward preparation,abundant availability,and cost-competitiveness.Notably,layered Fe-based oxide cathodes are deemed to be one of the most promising candidates for the lowest price and easy-to-improve performance.Nevertheless,the challenges such as severe phase transitions,sluggish diffusion kinetics and interfacial degradation pose significant hurdles in achieving high-performance cathodes for SIBs.This review first briefly outlines the classification of layered structures and the working principle of layered oxides.Then,recent advances in modification strategies employed to address current issues with layered iron-based oxide cathodes are systematically reviewed,including ion doping,biphasic engineering and surface modification.Furthermore,the review not only outlines the prospects and development directions for layered Fe-based oxide cathodes but also provides novel insights and directions for future research endeavors for SIBs.展开更多
Due to excellent thermal insulation performance at room temperature and ultralow density,silica aero-gels are candidates for thermal insulation.However,at high temperatures,the thermal insulation prop-erty of silica a...Due to excellent thermal insulation performance at room temperature and ultralow density,silica aero-gels are candidates for thermal insulation.However,at high temperatures,the thermal insulation prop-erty of silica aerogels decreased greatly caused by transparency to heat radiation.Opacifiers introduced into silica sol can block heat radiation yet destroy the uniformity of aerogels.Herein,we designed and prepared a silica aerogel composite with oriented and layered silica fibers(SFs),SiC nanowires(SiC_(NWs)),and silica aerogels,which were prepared by papermaking,chemical vapor infiltration(CVI),and sol-gel respectively.Firstly,oriented and layered SFs made still air a wall to block heat transfer by the solid phase.Secondly,SiC_(NWs) were grown in situ on the surface of SFs evenly to weave into the network,and the network reduced the gaseous thermal conductivity by dividing cracks in SFs/SiC_(NWs)/SA.Thirdly,SiC_(NWs) weakened the heat transfer by radiation at high temperatures.Therefore,SFs/SiC_(NWs)/SA presented remarkable thermal insulation(0.017 W(m K)^(-1) at 25℃,0.0287 W(m K)^(-1) at 500℃,and 0.094 W(m K)^(-1) at 1000℃).Besides,SFs/SiC_(NWs)/SA exhibited remarkable thermal stability(no size transform after being heat treated at 1000℃ for 1800 s)and tensile strength(0.75 MPa).These integrated properties made SFs/SiC_(NWs)/SA a promising candidate for highly efficient thermal insulators.展开更多
Nickel-rich(Ni≥90%)layered oxides materials have emerged as a promising candidate for nextgeneration high-energy-density lithium-ion batteries(LIBs).However,their widespread application is hindered by structural fati...Nickel-rich(Ni≥90%)layered oxides materials have emerged as a promising candidate for nextgeneration high-energy-density lithium-ion batteries(LIBs).However,their widespread application is hindered by structural fatigue and lattice oxygen loss.In this work,an epitaxial surface rock-salt nanolayer is successfully developed on the LiNi_(0.9)Co_(0.1)O_(2)sub-surface via heteroatom anchoring utilizing high-valence element molybdenum modification.This in-situ formed conformal buffer phase with a thickness of 1.2 nm effectively suppresses the continuous interphase side-reactions,and thus maintains the excellent structure integrity at high voltage.Furthermore,theoretical calculations indicate that the lattice oxygen reversibility in the anion framework of the optimized sample is obviously enhanced due to the higher content of O 2p states near the Fermi level than that of the pristine one.Meanwhile,the stronger Mo-O bond further reduces cell volume alteration,which improves the bulk structure stability of modified materials.Besides,the detailed charge compensation mechanism suggests that the average oxidation state of Ni is reduced,which induces more active Li+participating in the redox reactions,boosting the cell energy density.As a result,the uniquely designed cathode materials exhibit an extraordinary discharge capacity of 245.4 mAh g^(-1)at 0.1 C,remarkable rate performance of 169.3 mAh g^(-1)at 10 C at 4.5 V,and a high capacity retention of 70.5% after 1000 cycles in full cells at a high cut-off voltage of 4.4 V.This strategy provides an valuable insight into constructing distinctive heterostructure on highperformance Ni-rich layered cathodes for LIBs.展开更多
Facilitating anion redox chemistry is an effective strategy to increase the capacity of layered oxides for sodium-ion batteries.Nevertheless,there remains a paucity of literature pertaining to the oxygen redox chemist...Facilitating anion redox chemistry is an effective strategy to increase the capacity of layered oxides for sodium-ion batteries.Nevertheless,there remains a paucity of literature pertaining to the oxygen redox chemistry of O3-type layered oxide cathode materials.This work systematically investigates the effect of Fe doping on the anionic oxygen redox chemistry and electrochemical reactions in O3-NaNi_(0.4)Cu_(0.1)Mn_(0.4)Ti_(0.1)O_(2).The results of the density functional theory(DFT)calculations indicate that the electrons of the O 2p occupy a higher energy level.In the ex-situ X-ray photoelectron spectrometer(XPS)of O 1s,the addition of Fe facilitates the lattice oxygen(O^(n-))to exhibit enhanced activity at 4.45 V.The in-situ X-ray diffraction(XRD)demonstrates that the doping of Fe effectively suppresses the Y phase transition at high voltages.Furthermore,the Galvanostatic Intermittent Titration Technique(GITT)data indicate that Fe doping significantly increases the Na~+migration rate at high voltages.Consequently,the substitution of Fe can elevate the cut-off voltage to 4.45 V,thereby facilitating electron migration from O^(2-).The redox of O^(2-)/O^(n-)(n<2)contributes to the overall capacity.O3-Na(Ni_(0.4)Cu_(0.1)Mn_(0.4)Ti_(0.1))_(0.92)Fe_(0.08)O_(2)provides an initial discharge specific capacity of 180.55 mA h g^(-1)and71.6%capacity retention at 0.5 C(1 C=240 mA g^(-1)).This work not only demonstrates the beneficial impact of Fe substitution for promoting the redox activity and reversibility of O^(2-)in 03-type layered oxides,but also guarantees the structural integrity of the cathode materials at high voltages(>4.2 V).It offers a novel avenue for investigating the anionic redox reaction in O3-type layered oxides to design advanced cathode materials.展开更多
Layered double hydroxides(LDHs)have emerged as a promising class of photocatalysts with remarkable properties for diverse energy and environmental-related applications.This review offers insights into recent advances ...Layered double hydroxides(LDHs)have emerged as a promising class of photocatalysts with remarkable properties for diverse energy and environmental-related applications.This review offers insights into recent advances in LDH-based photocatalysts,focusing on their synthesis methods,structural properties,and photocatalytic performance.The unique structure of LDHs,characterized by positively charged metal hydroxide layers and intercalated anions,presents opportunities for tailoring their properties to enhance photocatalytic performance.The mechanisms for pollutant degradation,water splitting,and CO_(2) reduction are discussed,along with strategies to enhance the efficacy and stability of LDH-based photocatalysts.The photocatalytic mechanisms of LDHs for various reactions,including pollutant degradation,water splitting,and CO_(2) reduction,are discussed.Additionally,strategies for enriching the efficacy and stability of LDH-based photocatalysts are explored.This review underscores the significant potential of LDHs as versatile and efficient photocatalysts for addressing current environmental and energy challenges.展开更多
Expanding the cutoff voltage of layered oxide cathodes for sodium-ion batteries(SIBs)is crucial for overcoming their existing energy density limitations.However,cationic/anodic redox-triggered multiple phase transitio...Expanding the cutoff voltage of layered oxide cathodes for sodium-ion batteries(SIBs)is crucial for overcoming their existing energy density limitations.However,cationic/anodic redox-triggered multiple phase transitions and unfavorable interfacial side reactions accelerate capacity and voltage decay.Herein,we present a straightforward melting plus reactive wetting strategy using H_(3)BO_(3)for surface modification of O_(3)-type Na_(0.9)Cu_(0.12)Ni_(0.33)Mn_(0.4)Ti_(0.15)O_(2)(CNMT).The transformation of H_(3)BO_(3)from solid to liquid under mild heating facilitates the uniform dispersion and complete surface coverage of CNMT particles.By neutralizing the residual alkali and extracting Na^(+)from the CNMT lattice,H_(3)BO_(3)forms a multifunctional Na_(2)B_(2)O_(5)-dominated layer on the CNMT surface.This Na_(x)B_(y)O_(z)(NBO)layer plays a positive role in providing low-barrier Na^(+)transport channels,suppressing phase transitions,and minimizing the generation of O_(2)/CO_(2)gases and resistive byproducts.As a result,at a charge cutoff voltage of 4.5 V,the NBO-coated CNMT delivers a high discharge capacity of 149,1 mAh g^(-1)at 10 mA g^(-1)and exhibits excellent cycling stability at 100 mA g^(-1)over 200 cycles with a higher capacity retention than that of pristine CNMT(86,4%vs,62.1%).This study highlights the effectiveness of surface modification using lowmelting-point solid acids,with potential applications for other layered oxide cathode materials to achieve stable high-voltage cycling.This proposed strategy opens new avenues for the construction of highquality coatings for high-voltage layered oxide cathodes in SIBs.展开更多
Two-dimensional transition metal carbon/nitrides(MXenes)have emerged as prominent materials in the development of high-performance electromagnetic interference(EMI)shielding films owing to their ex-ceptional electrica...Two-dimensional transition metal carbon/nitrides(MXenes)have emerged as prominent materials in the development of high-performance electromagnetic interference(EMI)shielding films owing to their ex-ceptional electrical conductivity,special layered structure,and chemically active surfaces.Substantial ef-forts have been devoted to addressing the poor mechanical strength and limited functionality of pure MXene films through structural design and interfacial reinforcement.However,there is a notable lack of a systematic review of the research on MXene-based EMI shielding films with multi-layer structures,which could provide a theoretical foundation and technical guidance for the development and application of shielding films.This review aims to summarize the recent advancements in MXene-based layered films for EMI shielding.First,the structure and properties of MXene nanosheets are systematically introduced.Next,the optimization of layered structures and interfacial reinforcement strategies in MXene-based EMI shielding films are objectively reviewed,followed by a discussion of their multifunctional compatibility.Finally,future prospects and challenges for MXene-based layered EMI shielding films are highlighted.展开更多
基金supported by the National Natural Science Foundation of China(NSFC)(22302151,52502312)Natural Science Foundation of Hubei Province(2024AFB755,2024AFB267)+1 种基金Key Project of Hubei Provincial Department of Education Scientific Research Plan(F2023007)Wuhan Institute of Technology Graduate Education Innovation Fund(CX2024285)。
文摘Layered double hydroxides(LDHs)are promising electrocatalysts for the oxygen evolution reaction(OER),yet their practical application remains limited by poor electrical conductivity and sluggish reaction kinetics.In this work,we synthesize three high-entropy LDHs(HELDHs)featuring a hierarchical architecture of microspheres assembled from ultrathin nanosheets,via a simple hydrothermal method using a combination of low-cost,catalytically active transition metals(Fe,Co,Ni,Mn,Zn,Cu,and Cr).Among them,the FeCoNiMnZn HELDH exhibits outstanding OER performance,requiring an overpotential of only 306 mV to reach a current density of 100 mA cm^(-2).Notably,during 200 h of continuous operation,the device exhibits a stable and,in some cases,increasing current output.This exceptional activity is attributed to the formation of abundant cation vacancies,induced by Zn leaching,which enhance the intrinsic catalytic properties by optimizing the adsorption energies of key OER intermediates.Density functional theory calculations further validate that these vacancies modulate the electronic structure and lower reaction barriers,underscoring the effectiveness of cation-vacancy engineering in high-entropy systems for efficient and durable water oxidation catalysis.The optimized catalyst was further evaluated as the air cathode in a zinc-air battery,demonstrating practical electrochemical performance.
基金supported by the Ministry of Science and Technology of China(2025YFE0100200)the Natural Science Foundation of Tianjin(24JCJQJC00220 and 24ZXZSSS00310)+3 种基金the National Natural Science Foundation of China(22479080,92372203,and 92372001)the Open Foundation of Shanghai Jiao Tong University Shaoxing Research Institute of Renewable Energy and Molecular Engineering(JDSX2023003)the Fundamental Research Funds for the Central Universities of Nankai University(020-63253167)the"111 Center"(B25010)。
文摘Layered transition metal oxide cathode materials have garnered increasing attention for sodium-ion batteries(SIBs).However,they are plagued by the Jahn-Teller distortion of MnO6,Na^(+)/vacancy ordering,and irreversible lattice oxygen loss,which collectively lead to capacity fading and voltage decay.Herein,we report a P2-type material,Na_(0.67)Ni_(0.3)Mn_(0.6)Li_(0.09)Sn_(0.01)O_(2)(NNMO-Li0.09Sn0.01),modified with two closed-shell dopants(i.e.,Li^(+)and Sn^(4+)).Benefiting from the unique electronic configurations of closed-shell ions,NNMO-Li0.09Sn0.01 exhibits enhanced structural and electrochemical stability.Specifically,the incorporation of Li^(+)increases the Mn^(4+)/Mn3+ratio,thereby mitigating Jahn-Teller distortion during(de)sodiation process.In addition,Li^(+)disrupts the Ni/Mn ordering in the transition metal layer,suppressing Na^(+)/vacancy ordering.Meanwhile,the introduction of Sn^(4+)forms stronger Sn-O bonds(548 kJ mol-1),thereby enhancing the bonding strength between neighboring transition metal ions and surrounding oxygen atoms,effectively reducing oxygen loss during cycling.NNMO-Li0.09Sn0.01 exhibits significantly improved cycling stability,delivering a specific capacity of 90.3 mAh g^(-1)with 62.9%capacity retention after 50 cycles at 0.1 C(1 C=200 mA g^(-1)),along with 90.3%voltage retention.This substitution strategy based on closed-shell ions offers a viable approach for enhancing the structural stability of wide-voltage layered oxide cathodes.
基金supported by the National Natural Science Foundation of China (52402298, 52172224, 52202228, 22479112)the Science and Technology Correspondent Project of Tianjin(24YDTPJC00240)+3 种基金Science Research Project of Hebei Education Department (BJK2022011)Central Funds Guiding the Local Science and Technology Development of Hebei Province (236Z4404G)the Beijing Tianjin Hebei Basic Research Cooperation Special Project(E2024202273)Tianjin Sci.&Tech. Program (22YFYSHZ00220)
文摘O3-types layered cathode materials in sodium-ion batteries(SIBs)suffer from the obvious lattice distortion induced by the complex phase transitions during Na^(+)intercalation/deintercalation process,leading to severe structural collapse and performance degradation.Herein,a series of high valence tantalum(Ta^(5+))doped Na(Ni_(0.4)Fe_(0.2)Mn_(0.4))_(1−x)Ta_(x)O_(2)(x=0/0.0025/0.005/0.01)secondary spherical particles are firstly developed,where Ta^(5+)doping enables the refined primary grain with a tightly stacked rod-like morphology.Comprehensive structural analysis via Neutron powder diffraction(NPD)and Synchrotron radiation X-ray diffraction(SXRD)reveals an expanded NaO_(2)slab and a reduction in Na site vacancy.The potential charge compensation mechanism is further illustrated by X-ray absorption spectroscopy(XAS)and X-ray photoelectron spectroscopy(XPS),unveiling a partial reduction from Ni^(3+)to Ni^(2+)with Ta^(5+)doping.In situ X-ray diffraction(in situ XRD)suggests that the decorated sample undergoes a volume change as low as 0.8%,in contrast with the pristine one(1.5%).Thus,the optimized sample with x=0.005 retains an enhanced capacity retention up to 70.4%at 1 C after 300 cycles in half-cell and delivers a high energy density of 251 Wh kg^(-1)(0.1 C)and with a good capacity retention of 81.0%at 1 C after 200 cycles in full-cell.Our findings provide new insights into the mechanism of high valence Ta^(5+)doping in stabilizing layered oxides cathode materials for SIBs.
基金supported by the National Natural Science Foundation of China(Grant No.52178329),the China Scholarship Council(Grant No.202306130155)the Postgraduate Scientific Research Innovation Project of Hunan Province,China(Grant No.CX20230442).
文摘With the continuous development of the offshore wind industry,the design concept of composite foundation has been given attention in the past decade.This paper presents an accurate method for investigating the horizontal vibration of monopile-friction wheel composite foundations in layered saturated soil.Firstly,the three-dimensional continuum mechanics theory with the range of linear elasticity is introduced to calculate the frictional resistance distributed on the upper soil surface.Then,the resistances of multilayered soils and inviscid seawater to the pile shaft under horizontal harmonic excitation are obtained using Novak's plane strain model,Biot's porous media theory and radiationwave theory.Thirdly,the expressions for the deformation,bending moment and internal force of the Euler-Bernoulli pile are derived using the boundary conditions with definitephysical meaning and transfer matrix method.By comparing with the results of 1g laboratory test and the idealized formula reported by the literature,the rationality and accuracy of the developed dynamical model can be verified.Finally,this paper conducts a series of worked examples to investigate the influencesof the elastic modulus and thickness of three-layer saturated soil and the location of interlayer soil on the horizontal dynamic vibration of composite foundation.The results show that an increase in elastic modulus of the surface soil is an effective way to improve the dynamic stability of the composite foundation in service conditions.The conclusions drawn from the numerical examples can develop some guidelines for the current foundation design of offshore wind turbines.
基金supported by the Natural Science Research Project of Anhui Province Education Department for Excellent Young Scholars(Grant No.2024AH030007)the National Natural Science Foundation of China(Grant No.52202001)。
文摘Conventional Tb^(3+)-doped phosphors typically suffer from concentration quenching once the doping level exceeds a critical threshold.Consequently,the development of Tb^(3+)phosphors with intrinsic resistance to concentration quenching has become a key research focus.In this work,we successfully synthesized KBi(MoO_(4))_(2):x Tb^(3+)(x=0-100 at%)(denoted as KBM:x Tb^(3+))phosphors via a high-temperature solid-state reaction.Remarkably,no concentration quenching was observed across the entire doping range.This anti-quenching behavior originates from the large Tb^(3+)-Tb^(3+)interionic distance(>5Å)inherent to the quasi-layered crystal structure,which effectively suppresses multipole-interaction-mediated energy migration.At full Tb^(3+)substitution(x=100 at%),the material undergoes a structural phase transition from the monoclinic KBM phase to the triclinicα-KTb(MoO_(4))_(2)(α-KTM)phase.Theα-KTM phosphor exhibits excellent thermal stability(activation energy=0.6129 eV)and a single-exponential decay profile,whereas KBM:x Tb^(3+)(x<100%)display double-exponential decay behaviors,attributed to dual energy transfer pathways.These findings provide new insights into the luminescence mechanisms of high-concentration rare-earth-doped systems and offer guidance for designing nextgeneration anti-quenching phosphors.
基金support of the National Natural Science Foundation of China(Grant No.42207199)Zhejiang Provincial Natural Science Foundation of China(Grant Nos.ZCLMS25D0201 and LQ23D010002).
文摘Layered rocks are widely distributed in sedimentary and metamorphic rocks and show anisotropic deformation and strength due to the layered structures with apparent weak surfaces.This study summarizes the findings on the deformation and damage characteristics of layered rock masses and surrounding rocks.The physicomechanical properties of layered rocks with different properties(e.g.inclination,shear strength,tensile strength,shear stiffness,roughness,and layer spacing)and different lithological and stress conditions are analyzed.The results revealed that with increasing layer inclination angles,the deformation and strength parameters of the rock masses present U-shaped,W-shaped,incremental,decremental,and basically unchanged trends,which are closely related to their strength and stress conditions.The increase in layer strength and confining pressure effectively suppresses the deformation and strength anisotropy caused by layer weakening,and the rock mass shifts from“structure-controlled”to“stress-structure-controlled”deformation mode.Water will increase the anisotropic behavior of layered rock masses due to the degradation of bedding and bedrock performance.The anisotropic behavior of the layered surrounding rocks is analyzed to reveal how it affects the deformation and failure behaviors of tunnels.The asymmetric characteristics of surrounding rock deformation are closely related to the layer weakening,layer thickness,and in situ stress.These findings are crucial for understanding layered rock mass deformation and failure mechanisms,facilitating prediction and control of tunnel deformation.
基金support for this work by Key Research and Development Project of Henan Province(Grant.No.241111232300)the National Natural Science Foundation of China(Grant.No.52273085 and 52303113)the Open Fund of Yaoshan Laboratory(Grant.No.2024003).
文摘The morphological distribution of absorbent in composites is equally important with absorbents for the overall electromagnetic properties,but it is often ignored.Herein,a comprehensive consideration including electromagnetic component regulation,layered arrangement structure,and gradient concentration distribution was used to optimize impedance matching and enhance electromagnetic loss.On the microscale,the incorporation of magnetic Ni nanoparticles into MXene nanosheets(Ni@MXene)endows suitable intrinsic permittivity and permeability.On the macroscale,the layered arrangement of Ni@MXene increases the effective interaction area with electromagnetic waves,inducing multiple reflection/scattering effects.On this basis,according to the analysis of absorption,reflection,and transmission(A-R-T)power coefficients of layered composites,the gradient concentration distribution was constructed to realize the impedance matching at low-concentration surface layer,electromagnetic loss at middle concentration interlayer and microwave reflection at high-concentration bottom layer.Consequently,the layered gradient composite(LG5-10-15)achieves complete absorption coverage of X-band at thickness of 2.00-2.20 mm with RL_(min) of-68.67 dB at 9.85 GHz in 2.05 mm,which is 199.0%,12.6%,and 50.6%higher than non-layered,layered and layered descending gradient composites,respectively.Therefore,this work confirms the importance of layered gradient structure in improving absorption performance and broadens the design of high-performance microwave absorption materials.
基金financially supported by the National Natural Science Foundation of China(No.12304077)the Natural Science Foundation of Science and Technology Department of Sichuan Province(No.23NSFSC6224)+3 种基金Sichuan Science and Technology Program(No.2024NSFSC0989)the Key Laboratory of Computational Physics of Sichuan Province(No.YBUJSWL-YB-2022-03)the Material Corrosion and Protection Key Laboratory of Sichuan Province(No.2023CL14 and No.2023CL01)the National Innovation Practice Project(No.202411079005S).
文摘Oxygen release and electrolyte decomposition under high voltage endlessly exacerbate interfacial ramifications and structu ral degradation of high energy-density Li-rich layered oxide(LLO),leading to voltage and capacity fading.Herein,the dual-strategy of Cr,B complex coating and local gradient doping is simultaneously achieved on LLO surface by a one-step wet chemical reaction at room temperature.Density functional theory(DFT)calculations prove that stable B-O and Cr-O bonds through the local gradient doping can significantly reduce the high-energy O 2p states of interfacial lattice O,which is also effective for the near-surface lattice O,thus greatly stabilizing the LLO surface,Besides,differential electrochemical mass spectrometry(DEMS)indicates that the Cr_(x)B complex coating can adequately inhibit oxygen release and prevents the migration or dissolution of transition metal ions,including allowing speedy Li^(+)migration,The voltage and capacity fading of the modified cathode(LLO-C_(r)B)are adequately suppressed,which are benefited from the uniformly dense cathode electrolyte interface(CEI)composed of balanced organic/inorganic composition.Therefore,the specific capacity of LLO-CrB after 200 cycles at 1C is 209.3 mA h g^(-1)(with a retention rate of 95.1%).This dual-strategy through a one-step wet chemical reaction is expected to be applied in the design and development of other anionic redox cathode materials.
基金supported by the National Natural Science Foundation of China(No.21805018)by Sichuan Science and Technology Program(Nos.2022ZHCG0018,2023NSFSC0117 and 2023ZHCG0060)Yibin Science and Technology Program(No.2022JB005)and China Postdoctoral Science Foundation(No.2022M722704).
文摘Layered transition metal oxides have emerged as promising cathode materials for sodium ion batteries.However,irreversible phase transitions cause structural distortion and cation rearrangement,leading to sluggish Na+dynamics and rapid capacity decay.In this study,we propose a medium-entropy cathode by simultaneously introducing Fe,Mg,and Li dopants into a typical P2-type Na_(0.75)Ni_(0.25)Mn_(0.75)O_(2)cathode.The modified Na_(0.75)Ni_(0.2125)Mn_(0.6375)Fe_(0.05)Mg_(0.05)Li_(0.05)O_(2)cathode predominantly exhibits a main P2 phase(93.5%)with a minor O3 phase(6.5%).Through spectroscopy techniques and electrochemical investigations,we elucidate the redox mechanisms of Ni^(2+/3+/4+),Mn^(3+/4+),Fe^(3+/4+),and O_(2)-/O_(2)^(n-)during charging/discharging.The medium-entropy doping mitigates the detrimental P2-O_(2)phase transition at high-voltage,replacing it with a moderate and reversible structural evolution(P2-OP4),thereby enhancing structural stability.Consequently,the modified cathode exhibits a remarkable rate capacity of 108.4 mAh·g^(-1)at 10C,with a capacity retention of 99.0%after 200 cycles at 1C,82.5%after 500 cycles at 5C,and 76.7%after 600 cycles at 10C.Furthermore,it also demonstrates superior electrochemical performance at high cutoff voltage of 4.5 V and extreme temperature(55 and 0℃).This work offers solutions to critical challenges in sodium ion batteries cathode materials.
基金supported by the National Key R&D Program of China(No.2022YFB2404400)the National Natural Science Foundation of China(Nos.U23A20577,52372168,92263206 and 21975006)+1 种基金the“The Youth Beijing Scholars program”(No.PXM2021_014204_000023)the Beijing Natural Science Foundation(Nos.2222001 and KM202110005009).
文摘The cobalt-free Mn-based Li-rich layered oxide material has the advantages of low cost,high energy density,and good performance at low temperatures,and is the promising choice for energy storage batteries.However,the long-cycling stability of batteries needs to be improved.Herein,the Mn-based Li-rich cathode materials with small amounts of Li2 MnO3 crystal domains and gradient doping of Al and Ti elements from the surface to the bulk have been developed to improve the structure and interface stability.Then the batteries with a high energy density of 600 Wh kg^(-1),excellent capacity retention of 99.7%with low voltage decay of 0.03 mV cycle^(-1) after 800 cycles,and good rates performances can be achieved.Therefore,the structure and cycling stability of low voltage Mn-based Li-rich cathode materials can be significantly improved by the bulk structure design and interface regulation,and this work has paved the way for developing low-cost and high-energy Mn-based energy storage batteries with long lifetime.
基金financially supported by Guangdong Province Basic and Applied Basic Research Fund Project(Grant No.2022B1515250009)Liaoning Provincial Natural Science Foundation-Doctoral Research Start-up Fund Project(Grant No.2024-BSBA-05)+1 种基金Major Science and Technology Innovation Project in Shandong Province(Grant No.2024CXGC010803)the National Natural Science Foundation of China(Grant Nos.52271269 and 12302147).
文摘The umbilical,a key component in offshore energy extraction,plays a vital role in ensuring the stable operation of the entire production system.The extensive variety of cross-sectional components creates highly complex layout combinations.Furthermore,due to constraints in component quantity and geometry within the cross-sectional layout,filler bodies must be incorporated to maintain cross-section performance.Conventional design approaches based on manual experience suffer from inefficiency,high variability,and difficulties in quantification.This paper presents a multi-level automatic filling optimization design method for umbilical cross-sectional layouts to address these limitations.Initially,the research establishes a multi-objective optimization model that considers compactness,balance,and wear resistance of the cross-section,employing an enhanced genetic algorithm to achieve a near-optimal layout.Subsequently,the study implements an image processing-based vacancy detection technique to accurately identify cross-sectional gaps.To manage the variability and diversity of these vacant regions,the research introduces a multi-level filling method that strategically selects and places filler bodies of varying dimensions,overcoming the constraints of uniform-size fillers.Additionally,the method incorporates a hierarchical strategy that subdivides the complex cross-section into multiple layers,enabling layer-by-layer optimization and filling.This approach reduces manufac-turing equipment requirements while ensuring practical production process feasibility.The methodology is validated through a specific umbilical case study.The results demonstrate improvements in compactness,balance,and wear resistance compared with the initial cross-section,offering novel insights and valuable references for filler design in umbilical cross-sections.
基金supported by the National Natural Science Foundation of China(Grant No.W2412060,22325902 and 52171215)the State Key Laboratory of Clean Energy Utilization(Open Fund Project No.ZJUCEU2023002)。
文摘Sodium-ion batteries(SIBs)have attracted significant attention in large-scale energy storage system because of their abundant sodium resource and cost-effectiveness.Layered oxide materials are particularly promising as SIBs cathodes due to their high theoretical capacities and facile synthesis.However,their practical applications are hindered by the limitations in energy density and cycling stability.The comprehensive understanding of failure mechanisms within bulk structure and at the cathode/electrolyte interface of cathodes is still lacking.In this review,the issues related to bulk phase degradation and surface degradation,such as irreversible phase transitions,cation migration,transition metal dissolution,air/moisture instability,intergranular cracking,interfacial reactions,and reactive oxygen loss,are discussed.The latest advances and strategies to improve the stability of layered oxide cathodes and full cells are provided,as well as our perspectives on the future development of SIBs.
基金financially supported by the National Natural Science Foundation of China(NSFC)(52274295)the Natural Science Foundation of Hebei Province(E2021501029)+3 种基金the Fundamental Research Funds for the Central Universities(N2423051,N2423053,N2302016,N2423019,N2323013,N2423005)the Science and Technology Project of Hebei Education Department(QN2024238)the Basic Research Program Project of Shijiazhuang City for Universities Stationed in Hebei Province(241790937A)the Science and Technology Project of Qinhuangdao City in 2023.
文摘Mn-based layered oxides(KMO)have emerged as one of the promising low-cost cathodes for potassiumion batteries(PIBs).However,due to the multiple-phase transitions and the distortion in the MnO6structure induced by the Jahn-Teller(JT)effect associated with Mn-ion,the cathode exhibits poor structural stability.Herein,we propose a strategy to enhance structural stability by introducing robust metal-oxygen(M-O)bonds,which can realize the pinning effect to constrain the distortion in the transition metal(TM)layer.Concurrently,all the elements employed have exceptionally high crustal abundance.As a proof of concept,the designed K_(0.5)Mn_(0.9)Mg_(0.025)Ti_(0.025)Al_(0.05)O_(2)cathode exhibited a discharge capacity of approximately 100 mA h g^(-1)at 20 mA g^(-1)with 79%capacity retention over 50 cycles,and 73%capacity retention over 200 cycles at 200 mA g^(-1),showcased much better battery performance than the designed cathode with less robust M-O bonds.The properties of the formed M-O bonds were investigated using theoretical calculations.The enhanced dynamics,mitigated JT effect,and improved structural stability were elucidated through the in-situ X-ray diffractometer(XRD),in-situ electrochemical impedance spectroscopy(EIS)(and distribution of relaxation times(DRT)method),and ex-situ X-ray absorption fine structure(XAFS)tests.This study holds substantial reference value for the future design of costeffective Mn-based layered cathodes for PIBs.
基金supported by the National Natural Science Foundation of China(no.52374301)the Open Project of Guangxi Key Laboratory of Electrochemical Energy Materials(no.GXUEEM2024001)+2 种基金the Hebei Provincial Natural Science Foundation(no.E2024501010)the Shijiazhuang Basic Research Project(no.241790667A)the Performance subsidy fund for Key Laboratory of Dielectric and Electrolyte Functional Material Hebei Province(no.22567627H)。
文摘Sodium-ion batteries(SIBs)have the advantages of environmental friendliness,cost-effectiveness,and high energy density,which are considered one of the most promising candidates for lithium-ion batteries(LIBs).The cathode materials influence the cost and energy output of SIBs.Therefore,the development of advanced cathode materials is crucial for the practical application of SIBs.Among various cathode materials,layered transition metal oxides(LTMOs)have received widespread attention owing to their straightforward preparation,abundant availability,and cost-competitiveness.Notably,layered Fe-based oxide cathodes are deemed to be one of the most promising candidates for the lowest price and easy-to-improve performance.Nevertheless,the challenges such as severe phase transitions,sluggish diffusion kinetics and interfacial degradation pose significant hurdles in achieving high-performance cathodes for SIBs.This review first briefly outlines the classification of layered structures and the working principle of layered oxides.Then,recent advances in modification strategies employed to address current issues with layered iron-based oxide cathodes are systematically reviewed,including ion doping,biphasic engineering and surface modification.Furthermore,the review not only outlines the prospects and development directions for layered Fe-based oxide cathodes but also provides novel insights and directions for future research endeavors for SIBs.
基金supported by the National Natural Science Foun-dation of China(Grant No.U2167214).
文摘Due to excellent thermal insulation performance at room temperature and ultralow density,silica aero-gels are candidates for thermal insulation.However,at high temperatures,the thermal insulation prop-erty of silica aerogels decreased greatly caused by transparency to heat radiation.Opacifiers introduced into silica sol can block heat radiation yet destroy the uniformity of aerogels.Herein,we designed and prepared a silica aerogel composite with oriented and layered silica fibers(SFs),SiC nanowires(SiC_(NWs)),and silica aerogels,which were prepared by papermaking,chemical vapor infiltration(CVI),and sol-gel respectively.Firstly,oriented and layered SFs made still air a wall to block heat transfer by the solid phase.Secondly,SiC_(NWs) were grown in situ on the surface of SFs evenly to weave into the network,and the network reduced the gaseous thermal conductivity by dividing cracks in SFs/SiC_(NWs)/SA.Thirdly,SiC_(NWs) weakened the heat transfer by radiation at high temperatures.Therefore,SFs/SiC_(NWs)/SA presented remarkable thermal insulation(0.017 W(m K)^(-1) at 25℃,0.0287 W(m K)^(-1) at 500℃,and 0.094 W(m K)^(-1) at 1000℃).Besides,SFs/SiC_(NWs)/SA exhibited remarkable thermal stability(no size transform after being heat treated at 1000℃ for 1800 s)and tensile strength(0.75 MPa).These integrated properties made SFs/SiC_(NWs)/SA a promising candidate for highly efficient thermal insulators.
基金financially supported by the National Natural Science Foundation of China(No.52202228,52402298)funded by the Science Research Project of Hebei Education Department(No.BJK2022011)+3 种基金the Central Funds Guiding the Local Science and Technology Development of Hebei Province(No.236Z4404G)the Beijing Tianjin Hebei Basic Research Cooperation Special Project(No.E2024202273)the Science and Technology Correspondent Project of Tianjin(24YDTPJC00240)supported by the U.S.Department of Energy’s Office of Science,Office of Basic Energy Science,Materials Sciences and Engineering Division。
文摘Nickel-rich(Ni≥90%)layered oxides materials have emerged as a promising candidate for nextgeneration high-energy-density lithium-ion batteries(LIBs).However,their widespread application is hindered by structural fatigue and lattice oxygen loss.In this work,an epitaxial surface rock-salt nanolayer is successfully developed on the LiNi_(0.9)Co_(0.1)O_(2)sub-surface via heteroatom anchoring utilizing high-valence element molybdenum modification.This in-situ formed conformal buffer phase with a thickness of 1.2 nm effectively suppresses the continuous interphase side-reactions,and thus maintains the excellent structure integrity at high voltage.Furthermore,theoretical calculations indicate that the lattice oxygen reversibility in the anion framework of the optimized sample is obviously enhanced due to the higher content of O 2p states near the Fermi level than that of the pristine one.Meanwhile,the stronger Mo-O bond further reduces cell volume alteration,which improves the bulk structure stability of modified materials.Besides,the detailed charge compensation mechanism suggests that the average oxidation state of Ni is reduced,which induces more active Li+participating in the redox reactions,boosting the cell energy density.As a result,the uniquely designed cathode materials exhibit an extraordinary discharge capacity of 245.4 mAh g^(-1)at 0.1 C,remarkable rate performance of 169.3 mAh g^(-1)at 10 C at 4.5 V,and a high capacity retention of 70.5% after 1000 cycles in full cells at a high cut-off voltage of 4.4 V.This strategy provides an valuable insight into constructing distinctive heterostructure on highperformance Ni-rich layered cathodes for LIBs.
基金financial support from the Natural Science Foundation of Shandong Province of China(ZR2023ME051,ZR2019MEM020)。
文摘Facilitating anion redox chemistry is an effective strategy to increase the capacity of layered oxides for sodium-ion batteries.Nevertheless,there remains a paucity of literature pertaining to the oxygen redox chemistry of O3-type layered oxide cathode materials.This work systematically investigates the effect of Fe doping on the anionic oxygen redox chemistry and electrochemical reactions in O3-NaNi_(0.4)Cu_(0.1)Mn_(0.4)Ti_(0.1)O_(2).The results of the density functional theory(DFT)calculations indicate that the electrons of the O 2p occupy a higher energy level.In the ex-situ X-ray photoelectron spectrometer(XPS)of O 1s,the addition of Fe facilitates the lattice oxygen(O^(n-))to exhibit enhanced activity at 4.45 V.The in-situ X-ray diffraction(XRD)demonstrates that the doping of Fe effectively suppresses the Y phase transition at high voltages.Furthermore,the Galvanostatic Intermittent Titration Technique(GITT)data indicate that Fe doping significantly increases the Na~+migration rate at high voltages.Consequently,the substitution of Fe can elevate the cut-off voltage to 4.45 V,thereby facilitating electron migration from O^(2-).The redox of O^(2-)/O^(n-)(n<2)contributes to the overall capacity.O3-Na(Ni_(0.4)Cu_(0.1)Mn_(0.4)Ti_(0.1))_(0.92)Fe_(0.08)O_(2)provides an initial discharge specific capacity of 180.55 mA h g^(-1)and71.6%capacity retention at 0.5 C(1 C=240 mA g^(-1)).This work not only demonstrates the beneficial impact of Fe substitution for promoting the redox activity and reversibility of O^(2-)in 03-type layered oxides,but also guarantees the structural integrity of the cathode materials at high voltages(>4.2 V).It offers a novel avenue for investigating the anionic redox reaction in O3-type layered oxides to design advanced cathode materials.
基金supported by Karpagam Academy of Higher Education,India(No.KAHE/R-Acad/A1/Seed Money/024/2981)。
文摘Layered double hydroxides(LDHs)have emerged as a promising class of photocatalysts with remarkable properties for diverse energy and environmental-related applications.This review offers insights into recent advances in LDH-based photocatalysts,focusing on their synthesis methods,structural properties,and photocatalytic performance.The unique structure of LDHs,characterized by positively charged metal hydroxide layers and intercalated anions,presents opportunities for tailoring their properties to enhance photocatalytic performance.The mechanisms for pollutant degradation,water splitting,and CO_(2) reduction are discussed,along with strategies to enhance the efficacy and stability of LDH-based photocatalysts.The photocatalytic mechanisms of LDHs for various reactions,including pollutant degradation,water splitting,and CO_(2) reduction,are discussed.Additionally,strategies for enriching the efficacy and stability of LDH-based photocatalysts are explored.This review underscores the significant potential of LDHs as versatile and efficient photocatalysts for addressing current environmental and energy challenges.
基金supported by the National Natural Science Foundation of China(22169002 and 22469003)the Chongzuo Key Research and Development Program of China(20241205 and 20231204)the Counterpart Aid Project for Discipline Construction from Guangxi University(2023M02)。
文摘Expanding the cutoff voltage of layered oxide cathodes for sodium-ion batteries(SIBs)is crucial for overcoming their existing energy density limitations.However,cationic/anodic redox-triggered multiple phase transitions and unfavorable interfacial side reactions accelerate capacity and voltage decay.Herein,we present a straightforward melting plus reactive wetting strategy using H_(3)BO_(3)for surface modification of O_(3)-type Na_(0.9)Cu_(0.12)Ni_(0.33)Mn_(0.4)Ti_(0.15)O_(2)(CNMT).The transformation of H_(3)BO_(3)from solid to liquid under mild heating facilitates the uniform dispersion and complete surface coverage of CNMT particles.By neutralizing the residual alkali and extracting Na^(+)from the CNMT lattice,H_(3)BO_(3)forms a multifunctional Na_(2)B_(2)O_(5)-dominated layer on the CNMT surface.This Na_(x)B_(y)O_(z)(NBO)layer plays a positive role in providing low-barrier Na^(+)transport channels,suppressing phase transitions,and minimizing the generation of O_(2)/CO_(2)gases and resistive byproducts.As a result,at a charge cutoff voltage of 4.5 V,the NBO-coated CNMT delivers a high discharge capacity of 149,1 mAh g^(-1)at 10 mA g^(-1)and exhibits excellent cycling stability at 100 mA g^(-1)over 200 cycles with a higher capacity retention than that of pristine CNMT(86,4%vs,62.1%).This study highlights the effectiveness of surface modification using lowmelting-point solid acids,with potential applications for other layered oxide cathode materials to achieve stable high-voltage cycling.This proposed strategy opens new avenues for the construction of highquality coatings for high-voltage layered oxide cathodes in SIBs.
基金supported by the Key Research and Development Project of Henan Province of China(No.241111232300)the National Natural Science Foundation of China(Nos.52303113 and 5227308)the Open Project Program of Yaoshan Laboratory(No.2024003).
文摘Two-dimensional transition metal carbon/nitrides(MXenes)have emerged as prominent materials in the development of high-performance electromagnetic interference(EMI)shielding films owing to their ex-ceptional electrical conductivity,special layered structure,and chemically active surfaces.Substantial ef-forts have been devoted to addressing the poor mechanical strength and limited functionality of pure MXene films through structural design and interfacial reinforcement.However,there is a notable lack of a systematic review of the research on MXene-based EMI shielding films with multi-layer structures,which could provide a theoretical foundation and technical guidance for the development and application of shielding films.This review aims to summarize the recent advancements in MXene-based layered films for EMI shielding.First,the structure and properties of MXene nanosheets are systematically introduced.Next,the optimization of layered structures and interfacial reinforcement strategies in MXene-based EMI shielding films are objectively reviewed,followed by a discussion of their multifunctional compatibility.Finally,future prospects and challenges for MXene-based layered EMI shielding films are highlighted.
