Based on the functionally graded materials （FGMs） design concept, the laminated-graded graphite/cermets self-lubricating composite was prepared to achieve the integration of mechanical prop- erties and lubrication p...Based on the functionally graded materials （FGMs） design concept, the laminated-graded graphite/cermets self-lubricating composite was prepared to achieve the integration of mechanical prop- erties and lubrication performance of the cermet. The effects of the layer number and thickness of graded structure on residual stresses in the gradient composites were investigated by finite element method （FEM）. From the FEM analyses, the optimal gradient structure design was obtained correspond- ing to the following parameters： the number of graded layers n = 2 and the thickness of graded structure t = I ram. According to the optimum design, a graded graphite/cermets self-lubricating material with two layers was fabricated by a typical powder metallurgy technique. Compared with the homogenous graphite/cermets composite, the surface hardness and indentation fracture toughness of graded compos- ite were increased by approximately 15.9% and 6.3%, respectively. The results of X-ray diffraction （XRD） stress measurement identified the existence of residual compressive stress on the surface of graded com- posite. Additionally, the friction and wear tests revealed that the wear resistance of the graphite/cermets self-lubricating composite was improved significantly via the graded structural design, whereas the coefficient of friction changed slightly.展开更多
We adopted the solution impregnation route with aluminum dihydrogen phosphate solution as liquid medium for effective surface modification on graphite substrate.The mass ratio of graphite to Al(H_(2)PO_(4))_(3) change...We adopted the solution impregnation route with aluminum dihydrogen phosphate solution as liquid medium for effective surface modification on graphite substrate.The mass ratio of graphite to Al(H_(2)PO_(4))_(3) changed from 0.5:1 to 4:1,and the impregnation time changed from 1 to 7 h.The typical composite phase change thermal storage materials doped with the as-treated graphite were fabricated using form-stable technique.To investigate the oxidation and anti-oxidation behavior of the impregnated graphite at high temperatures,the samples were put into a muffle furnace for a cyclic heat test.Based on SEM,EDS,DSC techniques,analyses on the impregnated technique suggested an optimized processing conditions of a 3 h impregnation time with the ratio of graphite:Al(H_(2)PO_(4))_(3) as 1:3 for graphite impregnation treatment.Further investigations on high-temperature phase change heat storage materials doped by the treated graphite suggested excellent oxidation resistance and thermal cycling performance.展开更多
Lithium-ion batteries(LIBs)are an electrochemical energy storage technology that has been widely used for portable electrical devices,electric vehicles,and grid storage,etc.To satisfy the demand for user convenience e...Lithium-ion batteries(LIBs)are an electrochemical energy storage technology that has been widely used for portable electrical devices,electric vehicles,and grid storage,etc.To satisfy the demand for user convenience especially for electric vehicles,the development of a fast-charging technology for LIBs has become a critical focus.In commercial LIBs,the slow kinetics of Li+intercalation into the graphite anode from the electrolyte solution is known as the main restriction for fast-charging.We summarize the recent advances in obtaining fast-charging graphite-based anodes,mainly involving modifications of the electrolyte solution and graphite anode.Specifically,strategies for increasing the ionic conductivity and regulating the Li+solvation/desolvation state in the electrolyte solution,as well as optimizing the fabrication and the intrinsic activity of graphite-based anodes are discussed in detail.This review considers practical ways to obtain fast Li+intercalation kinetics into a graphite anode from the electrolyte as well as analysing progress in the commercialization of fast-charging LIBs.展开更多
Magnesium potassium phosphate cement(MKPC)coatings exhibit potential for carbon steel protection but face challenges in practical application due to the preparation process and properties.This study develops flake gra...Magnesium potassium phosphate cement(MKPC)coatings exhibit potential for carbon steel protection but face challenges in practical application due to the preparation process and properties.This study develops flake graphite(FG)-modified MKPC coatings via spraying process,investigating the effects of FG size and dosage on phase composition,microstructure,mechanical properties,corrosion protection,and thermal conductivity.Results show that a low FG dosage(5 wt%)synergistically optimizes multifunctional performance.Compared to unmodified MKPC,FG2-1 exhibited exceptional impact resistance,associated with a 57%reduction in corrosion current density(icorr),a 356.3% increase in low-frequency impedance modulus(Z_(0.01 Hz))and a 37% increase in thermal conductivity.However,the coating with a high FG dosage(15 wt%)degraded performance due to defect accumulation and reduced crystallinity of KMgPO_(4)·6H_(2)O.This work advances the rational design of multifunctional inorganic coatings for extreme service environments requiring coupled corrosion protection and thermal management.展开更多
High-performance graphite materials have important roles in aerospace and nuclear reactor technologies because of their outstanding chemical stability and high-temperature performance.Their traditional production meth...High-performance graphite materials have important roles in aerospace and nuclear reactor technologies because of their outstanding chemical stability and high-temperature performance.Their traditional production method relies on repeated impregnation-carbonization and graphitization,and is plagued by lengthy preparation cycles and high energy consumption.Phase transition-assisted self-pressurized selfsintering technology can rapidly produce high-strength graphite materials,but the fracture strain of the graphite materials produced is poor.To solve this problem,this study used a two-step sintering method to uniformly introduce micro-nano pores into natural graphite-based bulk graphite,achieving improved fracture strain of the samples without reducing their density and mechanical properties.Using natural graphite powder,micron-diamond,and nano-diamond as raw materials,and by precisely controlling the staged pressure release process,the degree of diamond phase transition expansion was effectively regulated.The strain-to-failure of the graphite samples reached 1.2%,a 35%increase compared to samples produced by fullpressure sintering.Meanwhile,their flexural strength exceeded 110 MPa,and their density was over 1.9 g/cm^(3).The process therefore produced both a high strength and a high fracture strain.The interface evolution and toughening mechanism during the two-step sintering process were investigated.It is believed that the micro-nano pores formed have two roles:as stress concentrators they induce yielding by shear and as multi-crack propagation paths they significantly lengthen the crack propagation path.The two-step sintering phase transition strategy introduces pores and provides a new approach for increasing the fracture strain of brittle materials.展开更多
CeO_(2) based semiconductor are widely used in solar-driven photothermal catalytic dry reforming of methane(DRM)reaction,but still suffer from low activity and low light utilization efficiency.This study developed gra...CeO_(2) based semiconductor are widely used in solar-driven photothermal catalytic dry reforming of methane(DRM)reaction,but still suffer from low activity and low light utilization efficiency.This study developed graphite-CeO_(2) interfaces to enhance solar-driven photothermal catalytic DRM.Compared with carbon nanotubes-modified CeO_(2)(CeO_(2)-CNT),graphite-modified CeO_(2)(CeO_(2)-GRA)constructed graphite-CeO_(2) interfaces with distortion in CeO_(2),leading to the formation abundant oxygen vacancies.These graphite-CeO_(2) interfaces with oxygen vacancies enhanced optical absorption and promoted the generation and separation of photogenerated carriers.The high endothermic capacity of graphite elevated the catalyst surface temperature from 592.1−691.3℃,boosting light-to-thermal conversion.The synergy between photogenerated carriers and localized heat enabled Ni/CeO_(2)-GRA to achieve a CO production rate of 9985.6 mmol/(g·h)(vs 7192.4 mmol/(g·h)for Ni/CeO_(2))and a light-to-fuel efficiency of 21.8%(vs 13.8%for Ni/CeO_(2)).This work provides insights for designing graphite-semiconductor interfaces to advance photothermal catalytic efficiency.展开更多
The stability of matrix graphite under neutron irradiation and in corrosive environments is crucial for the safe operation of molten salt reactors(MSRs).Raman spectroscopy and a slow positron beam were employed to inv...The stability of matrix graphite under neutron irradiation and in corrosive environments is crucial for the safe operation of molten salt reactors(MSRs).Raman spectroscopy and a slow positron beam were employed to investigate the effects of He ion irradiation fluences and subsequent annealing on the microstructure and defects of the matrix graphite.He ions with 500 keV energy and fluences ranging from 1.1×10^(15)ions∕cm^(2)to 3.5×10^(17)ions∕cm^(2)were used to simulate neutron irradiation at 300 K.The samples with an irradiation fluence of 3.5×10^(16)ions∕cm^(2)were subjected to isochronal annealing at different temperatures(573 K,873 K and 1173 K)for 3 h.The Raman results revealed that the D peak gradually increased,whereas the intrinsic G peak decreased with increasing irradiation fluence.At the same irradiation fluence,the D peak gradually decreased,whereas the intrinsic G peak increased with increasing annealing temperature.Slow positron beam analysis demonstrated that the density or size of irradiation defects(vacancy type)increased with higher irradiation fluence,but decreased rapidly with increasing annealing temperature.The Raman spectral analysis of sample cross sections subjected to high irradiation fluences revealed the emergence of amorphization precisely at the depth where ion damage was most pronounced,whereas the surface retained its crystalline structure.Raman and positron annihilation analyses indicated that the matrix graphite exhibited good irradiation resistance to He ions at 300 K.However,vacancy-type defects induced by He ion irradiation exhibit poor thermal stability and can be easily removed during annealing.展开更多
The advancement of planar micro-supercapacitors(PMSCs)for micro-electromechanical systems(MEMS)has been significantly hindered by the challenge of achieving high energy and power densities.This study addresses this is...The advancement of planar micro-supercapacitors(PMSCs)for micro-electromechanical systems(MEMS)has been significantly hindered by the challenge of achieving high energy and power densities.This study addresses this issue by leveraging screen-printing technology to fabricate high-performance PMSCs using innovative composite ink.The ink,a synergistic blend of few-layer graphene(Gt),carbon black(CB),and NiCo_(2)O_(4),was meticulously mixed to form a conductive and robust coating that enhanced the capacitive performance of the PMSCs.The optimized ink formulation and printing process result in a micro-supercapacitor with an exceptional areal capacitance of 18.95 mF/cm^(2)and an areal energy density of 2.63μW·h/cm^(2)at a current density of 0.05 mA/cm^(2),along with an areal power density of 0.025 mW/cm^(2).The devices demonstrated impressive durability with a capacitance retention rate of 94.7%after a stringent 20000-cycle test,demonstrating their potential for long-term applications.Moreover,the PMSCs displayed excellent mechanical flexibility,with a capacitance decrease of only 3.43%after 5000 bending cycles,highlighting their suitability for flexible electronic devices.The ease of integrating these PMSCs into series and parallel configurations for customized power further underscores their practicality for integrated power supply solutions in various technologies.展开更多
The durability performance in molten aluminum with high chemical activity is considered to be a crucial factor for the application of traditional ceramicmatrix composites in the aluminum industry.Herein,novel Ti(C,N)c...The durability performance in molten aluminum with high chemical activity is considered to be a crucial factor for the application of traditional ceramicmatrix composites in the aluminum industry.Herein,novel Ti(C,N)cermet composites with excellent corrosion resistance,featuring distinct ratios of high-entropy alloy binders,were meticulously synthesized by spark plasma sintering(SPS).The synergetic effect of porosity and binder on the corrosion resistance was detailed analyzed.The results show that 8 wt%binder provides an optimum balance of porosity,hardness,fracture toughness and corrosion resistance of the cermets.The appealing corrosion resistance is intimately associated with the formation of a continuous layer consisting of Ti N/Al N,which is introduced through the decarburization of the Ti(C,N)cermets.Additionally,a corrosion mechanism is proposed to elucidate the formation of alternating morphologies within the reaction layers of the cermets.This work is beneficial for selecting structural materials for use in the aluminum industry.展开更多
As an alternative to lithium-ion batteries,aqueous zinc-graphite batteries(ZnGBs)are being explored as safer and low-cost options with the expectation of scalability to large energy storage systems.However,the current...As an alternative to lithium-ion batteries,aqueous zinc-graphite batteries(ZnGBs)are being explored as safer and low-cost options with the expectation of scalability to large energy storage systems.However,the currently adopted polyatomic and metal complex anion intercalation process at the graphite electrode in ZnGB exhibits poor electrochemical performances.Alternatively,incorporating halogen anions offers exceptional electrochemical performance to graphite electrodes due to their redox process.In this work,ZnGBs are assembled using a LiCl/ZnCl2/KBr^(-)based water-in-salt electrolyte,which efficiently supplies bromide(Br^(−))ions for conversion into Br_(x)^(−)and facilitates Br_(2)intercalation at the graphite electrode.The conversion and intercalation of bromine together enable the ZnGB to achieve a discharge capacity of 2.73 mAh/cm^(2)with 91.0%of coulombic efficiency(CE)while supporting high current density operations of up to 150 mA/cm^(2).With high energy density(4.56 Wh/cm^(2)),high power density(199.5 mW/cm^(2)),and excellent rate capability(∼93.0%CE at 150 mA/cm^(2)),the ZnGB is shown to operate efficiently for as much as 800 cycles.Beguilingly,an anode-free ZnGB offers enhanced stability for up to 1100 cycles without performance decay,matching the electrochemical performance of Zn metal electrodes.This work provides insights into the bromine reaction mechanism at graphite electrodes and the role of surface exfoliation in enabling efficient Br_(x)^(−)formation,along with Br_(2)intercalation,for achieving high-performance ZnGBs.展开更多
Although graphite(G)materials dominate the commercial lithium-ion battery(LIBs)anode market due to their excellent overall performance,their limited rate performance and cycle life hinder applications in highperforman...Although graphite(G)materials dominate the commercial lithium-ion battery(LIBs)anode market due to their excellent overall performance,their limited rate performance and cycle life hinder applications in highperformance fields.To improve the cycling and rate performance of graphite anodes,this study first employed economical and eco-friendly tannic acid(TA)as a carbon coating precursor to coat graphite surfaces viaπ-πstacking interactions.In an oxygen-rich alkaline environment,tannic acid undergoes oxidation polymerization and crosslinks with formaldehyde to form a polymer matrix that coats the graphite surface.After subsequent carbonization,carbon-coated graphite material(G@C)was successfully synthesized.Carbon coatings on graphite effectively lower LIB resistance,enhance lithium-ion diffusion,and prevent exfoliation during cycling,thereby significantly boosting rate performance and prolonging the cycle life of graphite.After 500 cycles at 2C,the specific capacity of G@C was 103.7 mAh g^(-1),with a retention of 89%.However,G exhibited only 68.7 mAh g^(-1) and 85%retention under identical conditions.This carbon-coated graphite modification strategy offers a novel,green,and economical approach for designing and tailoring graphite anode materials for lithium-ion batteries with long cycle life and high rate.展开更多
The operational lifespan of nuclear graphite is significantly affected by irradiation creep,yet the microstructural mechanism underlying this creep phenomenon remains unclear.Some theories attempt to link microstructu...The operational lifespan of nuclear graphite is significantly affected by irradiation creep,yet the microstructural mechanism underlying this creep phenomenon remains unclear.Some theories attempt to link microstructural evolution with creep behavior,but the rapid migration rate of defects under irradiation and loading makes it difficult to capture the specific evolution process experimentally,resulting in a lack of direct structural evidence.Therefore,in this study,molecular dynamics simulations are employed to investigate the irradiation behavior and microstructural migration under external loading.The aim is to provide microstructural evidence for theories such as the dislocation pinning-unpinning and crystal yielding.The results demonstrate that high tensile loads can increase the potential energy and reduce threshold displacement energy of graphite crystals.Consequently,displacement damage probability and creep rate increase,which is not considered in previous theories.Meanwhile,different creep mechanisms are observed at different damage states and applied loads.In low-dose damage states dominated by interstitials and vacancies,the pinning-unpinning process at basal plane may be caused by a defect diffusion mode.Under high stress levels,direct breaking of pinning structures occurs,leading to rapid migration of basal planes,demonstrating the microstructural evolution process of irradiated crystal yielding and plastic flow.In high-dose damage states characterized significantly by amorphous components,short-range atomic diffusion can become the dominant creep mechanism,and diffusion along the c-axis of graphite crystals is no longer constrained.These findings provide a crucial reference for understanding the irradiation and creep behavior of nuclear graphite in reactors.展开更多
Identifying the damage and fracture properties of nuclear graphite materials and accurately simulating them are crucial when designing graphite core structures.To simulate the damage evolution and crack propagation of...Identifying the damage and fracture properties of nuclear graphite materials and accurately simulating them are crucial when designing graphite core structures.To simulate the damage evolution and crack propagation of graphite under stress in a finite element model,compression tests on disks and three-point bending tests on center-notched beams for fine-grained graphite(CDI-1D and IG11 graphite)were conducted.During these tests,digital image correlation and electronic speckle pattern interferometry techniques were utilized to observe the surface full-field displacements of the specimens.A segmented finite element inverse analysis method was developed to characterize the graphite’s damage evolution by quantifying the reduction in Young’s modulus with tensile and compressive strains in disk specimens.The fracture energy and bilinear tensile softening curve of the graphite were determined by comparing the load–displacement responses of the three-point bending tests and the finite element simulation.Finally,by combining the identified damage laws with a fracture criterion based on fracture energy,a damage–fracture model was established and used to simulate tensile tests on L-shaped specimens with different fillet radii.Simulations indicate that the damage area at the fillet expands with increasing radius,creating a blunting effect that enhances the load-bearing capacity of the specimens.This damage–fracture model can be applied to simulate graphite components in core structures.展开更多
In order to avoid poor machinability caused by excessive hardness under high-silicon conditions in the traditional free-cutting graphited steel,it is important to develop a suitable silicon-saving,aluminum-containing ...In order to avoid poor machinability caused by excessive hardness under high-silicon conditions in the traditional free-cutting graphited steel,it is important to develop a suitable silicon-saving,aluminum-containing free-cutting steel.This study investigated the microstructure and graphite precipitation behavior of Fe–0.58C–1.0Al(wt%)steels with varying silicon contents(0.55wt%–2.67wt%)after tempering at different temperatures(680℃,715℃).The tempering structure and the precipitation behavior of graphite and Fe_(3)C in Fe–0.58C–1.0Al steels were systematically studied by optical microscopy(OM),field emission scanning electron microscopy(FESEM),and electron microprobe analyzer(EPMA).The results showed that,at both tempering temperatures,the microstructure of 0.55wt%Si steel is ferrite+granular Fe_(3)C,and the microstructures of 1.38wt%–2.67wt%Si steels are ferrite+petaloid graphite+granular Fe_(3)C.With increasing Si content from 1.38wt%to 2.67wt%at constant tempering temperature,the number density of graphite particles increases,though their average size decreases.Meanwhile,the number density and average size of Fe_(3)C in experimental steels continuously decrease with the increase of Si content.For 0.55wt%Si steel without graphite precipitation,increasing tempering temperature promotes the accumulation and growth of Fe_(3)C.For 1.38wt%–2.67wt%Si steels with graphite precipitation,higher tempering temperature promotes graphite particles growth while accelerating the decomposition and refinement of Fe_(3)C.Furthermore,compared with the experimental steels containing 0.55wt%Si,1.38wt%Si,and 2.67wt%Si,the 1.89wt%Si steel exhibits significantly lower hardness.Especially,when tempered at 715℃,Fe–0.58C–1.0Al steel with 1.89wt%Si exhibits enhanced graphitization behavior and reduced hardness,which is nearly HV 20 lower than previously reported Fe–0.55C–2.33Si steel.展开更多
Poor Li plating reversibility and high thermal runaway risks are key challenges for fast charging lithiumion batteries with graphite anodes.Herein,a dielectric and fire-resistant separator based on hybrid nanofibers o...Poor Li plating reversibility and high thermal runaway risks are key challenges for fast charging lithiumion batteries with graphite anodes.Herein,a dielectric and fire-resistant separator based on hybrid nanofibers of barium sulfate(BS)and bacterial cellulose(BC)is developed to synchronously enhance the battery's fast charging and thermal-safety performances.The regulation mechanism of the dielectric BS/BC separator in enhancing the Li^(+)ion transport and Li plating reversibility is revealed.(1)The Max-Wagner polarization electric field of the dielectric BS/BC separator can accelerate the desolvation of solvated Li^(+)ions,enhancing their transport kinetics.(2)Moreover,due to the charge balancing effect,the dielectric BS/BC separator homogenizes the electric field/Li^(+)ion flux at the graphite anode-separator interface,facilitating uniform Li plating and suppressing Li dendrite growth.Consequently,the fast-charge graphite anode with the BS/BC separator shows higher Coulombic efficiency(99.0%vs.96.9%)and longer cycling lifespan(100 cycles vs.59 cycles)than that with the polypropylene(PP)separator in the constantlithiation cycling test at 2 mA cm^(-2).The high-loading LiFePO4(15.5 mg cm^(-2))//graphite(7.5 mg cm^(-2))full cell with the BS/BC separator exhibits excellent fast charging performance,retaining 70%of its capacity after 500 cycles at a high rate of 2C,which is significantly better than that of the cell with the PP separator(retaining only 27%of its capacity after 500 cycles).More importantly,the thermally stable BS/BC separator effectively elevates the critical temperature and reduces the heat release rate during thermal runaway,thereby significantly enhancing the battery's safety.展开更多
N-doped graphite carbon sphere coated cobalt nanoparticle catalyst(Co@C-N-900),prepared by solvothermal-calcination method,is applied to activate peroxymonosulfate(PMS)for bisphenol A(BPA)elimination.The outcomes demo...N-doped graphite carbon sphere coated cobalt nanoparticle catalyst(Co@C-N-900),prepared by solvothermal-calcination method,is applied to activate peroxymonosulfate(PMS)for bisphenol A(BPA)elimination.The outcomes demonstrate that the Co@C-N-900 could effectively activate PMS,thereby causing efficient removal of BPA in water.In addition,the Co@C-N-900/PMS system also has the advantages of low metal leaching,applicability in high salinity environments,good selectivity and stability.Further investigations using electron paramagnetic resonance,chronoamperometry,and quenching experiments demonstrated that the Co@C-N-900/PMS system is a typical non-radical route with singlet oxygen(^(1)O_(2))as the main reactive oxygen species(ROS).Density functional theory calculations(DFT)indicate that N-doping can effectively regulate the charge distribution on the catalyst surface,generating acidic/alkaline sites favorable for PMS adsorption and activation.Furthermore,it also can enhance the interaction and charge transfer capacity between the Co@C-N-900 and PMS.Lastly,LC-QTOF-MS/MS analysis revealed two possible BPA degradation pathways:(1)^(1)O_(2)attacked the isopropyl group in BPA between the two phenyl groups,causingβ-scission to occur.(2)Following the oxidation of the hydroxyl group in the aromatic ring of BPA,^(1)O_(2)could cause furtherβ-scission.The prepared Co@C-N-900 catalyst is a very promising catalyst,which would offer a workable remedy for treating water pollution.展开更多
Correction:Nuclear Science and Techniques(2025)36:4 https://doi.org/10.1007/s41365-024-01548-5 In this article,the caption for Fig(s)1,3,and 4 was inadvert-ently truncated.The incorrect and the corrected captions are ...Correction:Nuclear Science and Techniques(2025)36:4 https://doi.org/10.1007/s41365-024-01548-5 In this article,the caption for Fig(s)1,3,and 4 was inadvert-ently truncated.The incorrect and the corrected captions are given below.展开更多
Water electrolysis for hydrogen production offers a promising solution to future energy crises and environmental challenges.Although platinum is an efficient catalyst for hydrogen evolution reactions(HERs),its high co...Water electrolysis for hydrogen production offers a promising solution to future energy crises and environmental challenges.Although platinum is an efficient catalyst for hydrogen evolution reactions(HERs),its high cost and stability challenges limit its widespread use.A novel platinum-based catalyst,comprising platinum nanoparticles on nitrogen-doped porous graphite(Pt-N-porous graphite),addresses these limitations.This catalyst prevents nanoparticle aggregation,provides a high specific surface area of 1308 m^(2)g^(-1),and enhances mass transfer and active site exposure.Additionally,it exhibits superior electrical conductivity compared to commercial Pt-C,enhancing charge transfer efficiency.The Pt-N-porous graphite catalyst achieves an overpotential of 99 mV at 100 mA cm^(-2)and maintains stable performance after 10,000 cycles.Applied as a catalyst-coated membrane(CCM)in a proton exchange membrane(PEM)electrolyzer,it demonstrates excellent performance.Thus,the industrially synthesizable Pt-N-porous graphite catalyst holds great potential for large-scale energy applications.展开更多
The recently reported silicon/graphite(Si/Gr)composite electrode with a layered structure is a promising approach to achieve high capacity and stable cycling of Si-based electrodes in lithium-ion batteries.However,the...The recently reported silicon/graphite(Si/Gr)composite electrode with a layered structure is a promising approach to achieve high capacity and stable cycling of Si-based electrodes in lithium-ion batteries.However,there is still a need to clarify why particular layered structures are effective and why others are ineffective or even detrimental.In this work,an unreported mechanism dominated by the porosity evolution of electrodes is proposed for the degradation behavior of layered Si/Gr electrodes.First,the effect of layering sequence on the overall electrode performance is investigated experimentally,and the results suggest that the cycling performance of the silicon-on-graphite(SG)electrode is much superior to that of the graphite-on-silicon electrode.To explain this phenomenon,a coupled mechanical-electrochemical porous electrode model is developed,in which the porosity is affected by the silicon expansion and the local constraints.The modeling results suggest that the weaker constraint of the silicon layer in the SG electrode leads to a more insignificant decrease in porosity,and consequently,the more stable cycling performance.The findings of this work provide new insights into the structural design of Si-based electrodes.展开更多
基金financially supported by the Nation Natural Science Foundation of China (Grant No.51575368)
文摘Based on the functionally graded materials （FGMs） design concept, the laminated-graded graphite/cermets self-lubricating composite was prepared to achieve the integration of mechanical prop- erties and lubrication performance of the cermet. The effects of the layer number and thickness of graded structure on residual stresses in the gradient composites were investigated by finite element method （FEM）. From the FEM analyses, the optimal gradient structure design was obtained correspond- ing to the following parameters： the number of graded layers n = 2 and the thickness of graded structure t = I ram. According to the optimum design, a graded graphite/cermets self-lubricating material with two layers was fabricated by a typical powder metallurgy technique. Compared with the homogenous graphite/cermets composite, the surface hardness and indentation fracture toughness of graded compos- ite were increased by approximately 15.9% and 6.3%, respectively. The results of X-ray diffraction （XRD） stress measurement identified the existence of residual compressive stress on the surface of graded com- posite. Additionally, the friction and wear tests revealed that the wear resistance of the graphite/cermets self-lubricating composite was improved significantly via the graded structural design, whereas the coefficient of friction changed slightly.
基金Funded by Scientific and Technological Innovation Project of Carbon Emission Peak and Carbon Neutrality of Jiangsu Province(No.BE2022028-4)。
文摘We adopted the solution impregnation route with aluminum dihydrogen phosphate solution as liquid medium for effective surface modification on graphite substrate.The mass ratio of graphite to Al(H_(2)PO_(4))_(3) changed from 0.5:1 to 4:1,and the impregnation time changed from 1 to 7 h.The typical composite phase change thermal storage materials doped with the as-treated graphite were fabricated using form-stable technique.To investigate the oxidation and anti-oxidation behavior of the impregnated graphite at high temperatures,the samples were put into a muffle furnace for a cyclic heat test.Based on SEM,EDS,DSC techniques,analyses on the impregnated technique suggested an optimized processing conditions of a 3 h impregnation time with the ratio of graphite:Al(H_(2)PO_(4))_(3) as 1:3 for graphite impregnation treatment.Further investigations on high-temperature phase change heat storage materials doped by the treated graphite suggested excellent oxidation resistance and thermal cycling performance.
文摘Lithium-ion batteries(LIBs)are an electrochemical energy storage technology that has been widely used for portable electrical devices,electric vehicles,and grid storage,etc.To satisfy the demand for user convenience especially for electric vehicles,the development of a fast-charging technology for LIBs has become a critical focus.In commercial LIBs,the slow kinetics of Li+intercalation into the graphite anode from the electrolyte solution is known as the main restriction for fast-charging.We summarize the recent advances in obtaining fast-charging graphite-based anodes,mainly involving modifications of the electrolyte solution and graphite anode.Specifically,strategies for increasing the ionic conductivity and regulating the Li+solvation/desolvation state in the electrolyte solution,as well as optimizing the fabrication and the intrinsic activity of graphite-based anodes are discussed in detail.This review considers practical ways to obtain fast Li+intercalation kinetics into a graphite anode from the electrolyte as well as analysing progress in the commercialization of fast-charging LIBs.
基金National Key Research and Development Program of China(2024YFB3714804)National Natural Science Foundation of China(52171277)+1 种基金Baima Lake Laboratory Joint Funds of the Zhejiang Provincial Natural Science Foundation of China(LBMHZ24E020001)Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering(2022SZ-TD006).
文摘Magnesium potassium phosphate cement(MKPC)coatings exhibit potential for carbon steel protection but face challenges in practical application due to the preparation process and properties.This study develops flake graphite(FG)-modified MKPC coatings via spraying process,investigating the effects of FG size and dosage on phase composition,microstructure,mechanical properties,corrosion protection,and thermal conductivity.Results show that a low FG dosage(5 wt%)synergistically optimizes multifunctional performance.Compared to unmodified MKPC,FG2-1 exhibited exceptional impact resistance,associated with a 57%reduction in corrosion current density(icorr),a 356.3% increase in low-frequency impedance modulus(Z_(0.01 Hz))and a 37% increase in thermal conductivity.However,the coating with a high FG dosage(15 wt%)degraded performance due to defect accumulation and reduced crystallinity of KMgPO_(4)·6H_(2)O.This work advances the rational design of multifunctional inorganic coatings for extreme service environments requiring coupled corrosion protection and thermal management.
基金Natural Science Foundation of Shanghai(24ZR1400800)he Natural Science Foundation of China(U23A20685,52073058,91963204)+1 种基金the National Key R&D Program of China(2021YFB3701400)Shanghai Sailing Program(23YF1400200)。
文摘High-performance graphite materials have important roles in aerospace and nuclear reactor technologies because of their outstanding chemical stability and high-temperature performance.Their traditional production method relies on repeated impregnation-carbonization and graphitization,and is plagued by lengthy preparation cycles and high energy consumption.Phase transition-assisted self-pressurized selfsintering technology can rapidly produce high-strength graphite materials,but the fracture strain of the graphite materials produced is poor.To solve this problem,this study used a two-step sintering method to uniformly introduce micro-nano pores into natural graphite-based bulk graphite,achieving improved fracture strain of the samples without reducing their density and mechanical properties.Using natural graphite powder,micron-diamond,and nano-diamond as raw materials,and by precisely controlling the staged pressure release process,the degree of diamond phase transition expansion was effectively regulated.The strain-to-failure of the graphite samples reached 1.2%,a 35%increase compared to samples produced by fullpressure sintering.Meanwhile,their flexural strength exceeded 110 MPa,and their density was over 1.9 g/cm^(3).The process therefore produced both a high strength and a high fracture strain.The interface evolution and toughening mechanism during the two-step sintering process were investigated.It is believed that the micro-nano pores formed have two roles:as stress concentrators they induce yielding by shear and as multi-crack propagation paths they significantly lengthen the crack propagation path.The two-step sintering phase transition strategy introduces pores and provides a new approach for increasing the fracture strain of brittle materials.
文摘CeO_(2) based semiconductor are widely used in solar-driven photothermal catalytic dry reforming of methane(DRM)reaction,but still suffer from low activity and low light utilization efficiency.This study developed graphite-CeO_(2) interfaces to enhance solar-driven photothermal catalytic DRM.Compared with carbon nanotubes-modified CeO_(2)(CeO_(2)-CNT),graphite-modified CeO_(2)(CeO_(2)-GRA)constructed graphite-CeO_(2) interfaces with distortion in CeO_(2),leading to the formation abundant oxygen vacancies.These graphite-CeO_(2) interfaces with oxygen vacancies enhanced optical absorption and promoted the generation and separation of photogenerated carriers.The high endothermic capacity of graphite elevated the catalyst surface temperature from 592.1−691.3℃,boosting light-to-thermal conversion.The synergy between photogenerated carriers and localized heat enabled Ni/CeO_(2)-GRA to achieve a CO production rate of 9985.6 mmol/(g·h)(vs 7192.4 mmol/(g·h)for Ni/CeO_(2))and a light-to-fuel efficiency of 21.8%(vs 13.8%for Ni/CeO_(2)).This work provides insights for designing graphite-semiconductor interfaces to advance photothermal catalytic efficiency.
基金supported by the National Natural Science Foundation of China(Nos.12005289,52072397)State Key Laboratory of Nuclear Detection and Electronics,University of Science and Technology of China(SKLPDE-KF-202316).
文摘The stability of matrix graphite under neutron irradiation and in corrosive environments is crucial for the safe operation of molten salt reactors(MSRs).Raman spectroscopy and a slow positron beam were employed to investigate the effects of He ion irradiation fluences and subsequent annealing on the microstructure and defects of the matrix graphite.He ions with 500 keV energy and fluences ranging from 1.1×10^(15)ions∕cm^(2)to 3.5×10^(17)ions∕cm^(2)were used to simulate neutron irradiation at 300 K.The samples with an irradiation fluence of 3.5×10^(16)ions∕cm^(2)were subjected to isochronal annealing at different temperatures(573 K,873 K and 1173 K)for 3 h.The Raman results revealed that the D peak gradually increased,whereas the intrinsic G peak decreased with increasing irradiation fluence.At the same irradiation fluence,the D peak gradually decreased,whereas the intrinsic G peak increased with increasing annealing temperature.Slow positron beam analysis demonstrated that the density or size of irradiation defects(vacancy type)increased with higher irradiation fluence,but decreased rapidly with increasing annealing temperature.The Raman spectral analysis of sample cross sections subjected to high irradiation fluences revealed the emergence of amorphization precisely at the depth where ion damage was most pronounced,whereas the surface retained its crystalline structure.Raman and positron annihilation analyses indicated that the matrix graphite exhibited good irradiation resistance to He ions at 300 K.However,vacancy-type defects induced by He ion irradiation exhibit poor thermal stability and can be easily removed during annealing.
基金supported by the Shanxi Province Central Guidance Fund for Local Science and Technology Development Project(YDZJSX2024D030)the National Natural Science Foundation of China(22075197,22278290)+2 种基金the Shanxi Province Key Research and Development Program Project(2021020660301013)the Shanxi Provincial Natural Science Foundation of China(202103021224079)the Research and Development Project of Key Core and Common Technology of Shanxi Province(20201102018).
文摘The advancement of planar micro-supercapacitors(PMSCs)for micro-electromechanical systems(MEMS)has been significantly hindered by the challenge of achieving high energy and power densities.This study addresses this issue by leveraging screen-printing technology to fabricate high-performance PMSCs using innovative composite ink.The ink,a synergistic blend of few-layer graphene(Gt),carbon black(CB),and NiCo_(2)O_(4),was meticulously mixed to form a conductive and robust coating that enhanced the capacitive performance of the PMSCs.The optimized ink formulation and printing process result in a micro-supercapacitor with an exceptional areal capacitance of 18.95 mF/cm^(2)and an areal energy density of 2.63μW·h/cm^(2)at a current density of 0.05 mA/cm^(2),along with an areal power density of 0.025 mW/cm^(2).The devices demonstrated impressive durability with a capacitance retention rate of 94.7%after a stringent 20000-cycle test,demonstrating their potential for long-term applications.Moreover,the PMSCs displayed excellent mechanical flexibility,with a capacitance decrease of only 3.43%after 5000 bending cycles,highlighting their suitability for flexible electronic devices.The ease of integrating these PMSCs into series and parallel configurations for customized power further underscores their practicality for integrated power supply solutions in various technologies.
基金financially supported by the National Natural Science Foundation of China(No.52271014)the Foundation of Education Bureau of Hunan Province(No.22B0163)Jiangxi Provincial Department of Education(No.GJJ2200819)。
文摘The durability performance in molten aluminum with high chemical activity is considered to be a crucial factor for the application of traditional ceramicmatrix composites in the aluminum industry.Herein,novel Ti(C,N)cermet composites with excellent corrosion resistance,featuring distinct ratios of high-entropy alloy binders,were meticulously synthesized by spark plasma sintering(SPS).The synergetic effect of porosity and binder on the corrosion resistance was detailed analyzed.The results show that 8 wt%binder provides an optimum balance of porosity,hardness,fracture toughness and corrosion resistance of the cermets.The appealing corrosion resistance is intimately associated with the formation of a continuous layer consisting of Ti N/Al N,which is introduced through the decarburization of the Ti(C,N)cermets.Additionally,a corrosion mechanism is proposed to elucidate the formation of alternating morphologies within the reaction layers of the cermets.This work is beneficial for selecting structural materials for use in the aluminum industry.
基金The authors acknowledge the University of Sharjah for financial support through a competitive research project grant(project number:23020406277)。
文摘As an alternative to lithium-ion batteries,aqueous zinc-graphite batteries(ZnGBs)are being explored as safer and low-cost options with the expectation of scalability to large energy storage systems.However,the currently adopted polyatomic and metal complex anion intercalation process at the graphite electrode in ZnGB exhibits poor electrochemical performances.Alternatively,incorporating halogen anions offers exceptional electrochemical performance to graphite electrodes due to their redox process.In this work,ZnGBs are assembled using a LiCl/ZnCl2/KBr^(-)based water-in-salt electrolyte,which efficiently supplies bromide(Br^(−))ions for conversion into Br_(x)^(−)and facilitates Br_(2)intercalation at the graphite electrode.The conversion and intercalation of bromine together enable the ZnGB to achieve a discharge capacity of 2.73 mAh/cm^(2)with 91.0%of coulombic efficiency(CE)while supporting high current density operations of up to 150 mA/cm^(2).With high energy density(4.56 Wh/cm^(2)),high power density(199.5 mW/cm^(2)),and excellent rate capability(∼93.0%CE at 150 mA/cm^(2)),the ZnGB is shown to operate efficiently for as much as 800 cycles.Beguilingly,an anode-free ZnGB offers enhanced stability for up to 1100 cycles without performance decay,matching the electrochemical performance of Zn metal electrodes.This work provides insights into the bromine reaction mechanism at graphite electrodes and the role of surface exfoliation in enabling efficient Br_(x)^(−)formation,along with Br_(2)intercalation,for achieving high-performance ZnGBs.
基金supported by the Science and Technology Projects of the State Grid Corporation of China(5500-202323102A-1-1-ZN).
文摘Although graphite(G)materials dominate the commercial lithium-ion battery(LIBs)anode market due to their excellent overall performance,their limited rate performance and cycle life hinder applications in highperformance fields.To improve the cycling and rate performance of graphite anodes,this study first employed economical and eco-friendly tannic acid(TA)as a carbon coating precursor to coat graphite surfaces viaπ-πstacking interactions.In an oxygen-rich alkaline environment,tannic acid undergoes oxidation polymerization and crosslinks with formaldehyde to form a polymer matrix that coats the graphite surface.After subsequent carbonization,carbon-coated graphite material(G@C)was successfully synthesized.Carbon coatings on graphite effectively lower LIB resistance,enhance lithium-ion diffusion,and prevent exfoliation during cycling,thereby significantly boosting rate performance and prolonging the cycle life of graphite.After 500 cycles at 2C,the specific capacity of G@C was 103.7 mAh g^(-1),with a retention of 89%.However,G exhibited only 68.7 mAh g^(-1) and 85%retention under identical conditions.This carbon-coated graphite modification strategy offers a novel,green,and economical approach for designing and tailoring graphite anode materials for lithium-ion batteries with long cycle life and high rate.
基金supported the Science and Technology Commission of Shanghai Municipality(No.21DZ2206900)。
文摘The operational lifespan of nuclear graphite is significantly affected by irradiation creep,yet the microstructural mechanism underlying this creep phenomenon remains unclear.Some theories attempt to link microstructural evolution with creep behavior,but the rapid migration rate of defects under irradiation and loading makes it difficult to capture the specific evolution process experimentally,resulting in a lack of direct structural evidence.Therefore,in this study,molecular dynamics simulations are employed to investigate the irradiation behavior and microstructural migration under external loading.The aim is to provide microstructural evidence for theories such as the dislocation pinning-unpinning and crystal yielding.The results demonstrate that high tensile loads can increase the potential energy and reduce threshold displacement energy of graphite crystals.Consequently,displacement damage probability and creep rate increase,which is not considered in previous theories.Meanwhile,different creep mechanisms are observed at different damage states and applied loads.In low-dose damage states dominated by interstitials and vacancies,the pinning-unpinning process at basal plane may be caused by a defect diffusion mode.Under high stress levels,direct breaking of pinning structures occurs,leading to rapid migration of basal planes,demonstrating the microstructural evolution process of irradiated crystal yielding and plastic flow.In high-dose damage states characterized significantly by amorphous components,short-range atomic diffusion can become the dominant creep mechanism,and diffusion along the c-axis of graphite crystals is no longer constrained.These findings provide a crucial reference for understanding the irradiation and creep behavior of nuclear graphite in reactors.
基金supported by the National Natural Science Foundation of China(No.52278251)Guizhou Provincial Sciences and Technology Projects(ZK[2022]Key 007).
文摘Identifying the damage and fracture properties of nuclear graphite materials and accurately simulating them are crucial when designing graphite core structures.To simulate the damage evolution and crack propagation of graphite under stress in a finite element model,compression tests on disks and three-point bending tests on center-notched beams for fine-grained graphite(CDI-1D and IG11 graphite)were conducted.During these tests,digital image correlation and electronic speckle pattern interferometry techniques were utilized to observe the surface full-field displacements of the specimens.A segmented finite element inverse analysis method was developed to characterize the graphite’s damage evolution by quantifying the reduction in Young’s modulus with tensile and compressive strains in disk specimens.The fracture energy and bilinear tensile softening curve of the graphite were determined by comparing the load–displacement responses of the three-point bending tests and the finite element simulation.Finally,by combining the identified damage laws with a fracture criterion based on fracture energy,a damage–fracture model was established and used to simulate tensile tests on L-shaped specimens with different fillet radii.Simulations indicate that the damage area at the fillet expands with increasing radius,creating a blunting effect that enhances the load-bearing capacity of the specimens.This damage–fracture model can be applied to simulate graphite components in core structures.
基金supports by the National Natural Science Foundation of China(No.52274311)the Natural Science Research Project of Anhui Educational Committee,China(No.2023AH051081).
文摘In order to avoid poor machinability caused by excessive hardness under high-silicon conditions in the traditional free-cutting graphited steel,it is important to develop a suitable silicon-saving,aluminum-containing free-cutting steel.This study investigated the microstructure and graphite precipitation behavior of Fe–0.58C–1.0Al(wt%)steels with varying silicon contents(0.55wt%–2.67wt%)after tempering at different temperatures(680℃,715℃).The tempering structure and the precipitation behavior of graphite and Fe_(3)C in Fe–0.58C–1.0Al steels were systematically studied by optical microscopy(OM),field emission scanning electron microscopy(FESEM),and electron microprobe analyzer(EPMA).The results showed that,at both tempering temperatures,the microstructure of 0.55wt%Si steel is ferrite+granular Fe_(3)C,and the microstructures of 1.38wt%–2.67wt%Si steels are ferrite+petaloid graphite+granular Fe_(3)C.With increasing Si content from 1.38wt%to 2.67wt%at constant tempering temperature,the number density of graphite particles increases,though their average size decreases.Meanwhile,the number density and average size of Fe_(3)C in experimental steels continuously decrease with the increase of Si content.For 0.55wt%Si steel without graphite precipitation,increasing tempering temperature promotes the accumulation and growth of Fe_(3)C.For 1.38wt%–2.67wt%Si steels with graphite precipitation,higher tempering temperature promotes graphite particles growth while accelerating the decomposition and refinement of Fe_(3)C.Furthermore,compared with the experimental steels containing 0.55wt%Si,1.38wt%Si,and 2.67wt%Si,the 1.89wt%Si steel exhibits significantly lower hardness.Especially,when tempered at 715℃,Fe–0.58C–1.0Al steel with 1.89wt%Si exhibits enhanced graphitization behavior and reduced hardness,which is nearly HV 20 lower than previously reported Fe–0.55C–2.33Si steel.
基金financially supported by the National Natural Science Foundation of China(Grant No.52202328,52372099)the Shanghai Sailing Program(22YF1455500).
文摘Poor Li plating reversibility and high thermal runaway risks are key challenges for fast charging lithiumion batteries with graphite anodes.Herein,a dielectric and fire-resistant separator based on hybrid nanofibers of barium sulfate(BS)and bacterial cellulose(BC)is developed to synchronously enhance the battery's fast charging and thermal-safety performances.The regulation mechanism of the dielectric BS/BC separator in enhancing the Li^(+)ion transport and Li plating reversibility is revealed.(1)The Max-Wagner polarization electric field of the dielectric BS/BC separator can accelerate the desolvation of solvated Li^(+)ions,enhancing their transport kinetics.(2)Moreover,due to the charge balancing effect,the dielectric BS/BC separator homogenizes the electric field/Li^(+)ion flux at the graphite anode-separator interface,facilitating uniform Li plating and suppressing Li dendrite growth.Consequently,the fast-charge graphite anode with the BS/BC separator shows higher Coulombic efficiency(99.0%vs.96.9%)and longer cycling lifespan(100 cycles vs.59 cycles)than that with the polypropylene(PP)separator in the constantlithiation cycling test at 2 mA cm^(-2).The high-loading LiFePO4(15.5 mg cm^(-2))//graphite(7.5 mg cm^(-2))full cell with the BS/BC separator exhibits excellent fast charging performance,retaining 70%of its capacity after 500 cycles at a high rate of 2C,which is significantly better than that of the cell with the PP separator(retaining only 27%of its capacity after 500 cycles).More importantly,the thermally stable BS/BC separator effectively elevates the critical temperature and reduces the heat release rate during thermal runaway,thereby significantly enhancing the battery's safety.
基金the financial support from Sichuan Science and Technology Program(No.2023NSFSC0847)Scientific Research and Innovation Team Program of Sichuan University of Science and Technology(No.SUSE652A003)+3 种基金Talent Introduction Project of Sichuan University of Science and Engineering(No.2021RC03)Talent Introduction Project of Sichuan University of Science and Engineering(No.2021RC05)the Undergraduate Training Program for Innovation and Entrepreneurship(No.CX2024042)The Innovation Fund of Postgraduate,Sichuan University of Science&Engineering(No.Y2024094)。
文摘N-doped graphite carbon sphere coated cobalt nanoparticle catalyst(Co@C-N-900),prepared by solvothermal-calcination method,is applied to activate peroxymonosulfate(PMS)for bisphenol A(BPA)elimination.The outcomes demonstrate that the Co@C-N-900 could effectively activate PMS,thereby causing efficient removal of BPA in water.In addition,the Co@C-N-900/PMS system also has the advantages of low metal leaching,applicability in high salinity environments,good selectivity and stability.Further investigations using electron paramagnetic resonance,chronoamperometry,and quenching experiments demonstrated that the Co@C-N-900/PMS system is a typical non-radical route with singlet oxygen(^(1)O_(2))as the main reactive oxygen species(ROS).Density functional theory calculations(DFT)indicate that N-doping can effectively regulate the charge distribution on the catalyst surface,generating acidic/alkaline sites favorable for PMS adsorption and activation.Furthermore,it also can enhance the interaction and charge transfer capacity between the Co@C-N-900 and PMS.Lastly,LC-QTOF-MS/MS analysis revealed two possible BPA degradation pathways:(1)^(1)O_(2)attacked the isopropyl group in BPA between the two phenyl groups,causingβ-scission to occur.(2)Following the oxidation of the hydroxyl group in the aromatic ring of BPA,^(1)O_(2)could cause furtherβ-scission.The prepared Co@C-N-900 catalyst is a very promising catalyst,which would offer a workable remedy for treating water pollution.
文摘Correction:Nuclear Science and Techniques(2025)36:4 https://doi.org/10.1007/s41365-024-01548-5 In this article,the caption for Fig(s)1,3,and 4 was inadvert-ently truncated.The incorrect and the corrected captions are given below.
基金funded by the National Natural Science Foundation of China(No.52202446)the Young Elite Scientists Sponsorship Program by CAST(No.2022QNRC001)+2 种基金the Young Elite Scientists Sponsorship Program by BAST(No.BYESS2023050)the Beijing Association for Science and Technology’s Golden-Bridge Seed Funding Program(No.ZZ22042)the Fundamental Research Funds for the Central Universities of China。
文摘Water electrolysis for hydrogen production offers a promising solution to future energy crises and environmental challenges.Although platinum is an efficient catalyst for hydrogen evolution reactions(HERs),its high cost and stability challenges limit its widespread use.A novel platinum-based catalyst,comprising platinum nanoparticles on nitrogen-doped porous graphite(Pt-N-porous graphite),addresses these limitations.This catalyst prevents nanoparticle aggregation,provides a high specific surface area of 1308 m^(2)g^(-1),and enhances mass transfer and active site exposure.Additionally,it exhibits superior electrical conductivity compared to commercial Pt-C,enhancing charge transfer efficiency.The Pt-N-porous graphite catalyst achieves an overpotential of 99 mV at 100 mA cm^(-2)and maintains stable performance after 10,000 cycles.Applied as a catalyst-coated membrane(CCM)in a proton exchange membrane(PEM)electrolyzer,it demonstrates excellent performance.Thus,the industrially synthesizable Pt-N-porous graphite catalyst holds great potential for large-scale energy applications.
基金supported by the National Natural Science Foundation of China(Grant Nos.12072183,12472174,and 12421002).
文摘The recently reported silicon/graphite(Si/Gr)composite electrode with a layered structure is a promising approach to achieve high capacity and stable cycling of Si-based electrodes in lithium-ion batteries.However,there is still a need to clarify why particular layered structures are effective and why others are ineffective or even detrimental.In this work,an unreported mechanism dominated by the porosity evolution of electrodes is proposed for the degradation behavior of layered Si/Gr electrodes.First,the effect of layering sequence on the overall electrode performance is investigated experimentally,and the results suggest that the cycling performance of the silicon-on-graphite(SG)electrode is much superior to that of the graphite-on-silicon electrode.To explain this phenomenon,a coupled mechanical-electrochemical porous electrode model is developed,in which the porosity is affected by the silicon expansion and the local constraints.The modeling results suggest that the weaker constraint of the silicon layer in the SG electrode leads to a more insignificant decrease in porosity,and consequently,the more stable cycling performance.The findings of this work provide new insights into the structural design of Si-based electrodes.
