The microstructure of positive electrode polycrystalline particles(secondary particles)directly affects their diffusion and mechanical properties.In this study,a quantitative evaluation of the effects of grain anisotr...The microstructure of positive electrode polycrystalline particles(secondary particles)directly affects their diffusion and mechanical properties.In this study,a quantitative evaluation of the effects of grain anisotropy on the overall diffusion and mechanical properties of secondary particles is conducted,which is based on a simplified 2D polycrystalline model with hexagonal anisotropic grains(primary particles)with different distributed orientations.The research results indicate that consistent grain orientation can promote the uniform distribution of lithium ions,while lower diffusion anisotropy can promote the diffusion of lithium ions along shorter paths,thereby improving the diffusion properties of secondary particles.Lower elastic anisotropy of grains and a grain orientation distribution with a 60°angle favor maintaining the macroscopic elastic isotropy of secondary particles.The study also found that when the number of grains is large enough and the orientation distribution is sufficiently random,secondary particles exhibit macroscopic diffusion isotropy and elastic isotropy.展开更多
The present work emphasizes the isolation of cellulose nanofiber(CNF)from the kenaf(Hibiscus cannabinus)bast through a chemo-mechanical process.In order to develop high CNF yield with superior properties of CNF for im...The present work emphasizes the isolation of cellulose nanofiber(CNF)from the kenaf(Hibiscus cannabinus)bast through a chemo-mechanical process.In order to develop high CNF yield with superior properties of CNF for improving compatibility in varied applications this method is proposed.The fiber purification involved pulping and bleaching treatments,whereas mechanical treatment was performed by grinding and high-pressure treatments.The kraft pulping as a delignification method followed by bleaching has successfully removed almost 99%lignin in the fiber with high pulp yield and delignification selectivity.The morphology of the fibers was characterized by scanning electron microscopy,which showed a smooth surface,fiber bundles,gel-shaped nanofiber,and an average size of 94.05 nm with 69%of CNF in 34–100 nm size.The chemo-mechanical process exhibited a more crystalline nature in CNF than pulp kenaf.The low zeta potential values exhibit the distribution of fibrils and colloidal suspension stability without any further agglomeration.A lower concentration of CNF is less stable exhibiting the product agglomeration.Therefore,the chemo-mechanical process for the isolation of CNF(Hibiscus cannabinus)from kenaf involves sustainable,low-cost,non-toxic,and cheap alternatives than other traditional methods.展开更多
Chemo-mechanical coupling exists in a lot of intelligent materials including hy- drogels, biological tissues and other soft materials. These materials are able to respond to ex- ternal stimulus, such as temperature, c...Chemo-mechanical coupling exists in a lot of intelligent materials including hy- drogels, biological tissues and other soft materials. These materials are able to respond to ex- ternal stimulus, such as temperature, chemical concentration, and pH value. In this paper, a one-dimensional theoretical model for chemo-mechanical coupling is proposed for analyzing the uniaxial stress/strain state of coupling materials. Based on the chemo-mechanical coupled gov- erning equation, the displacement function and concentration function are derived and the stress and chemical potential are obtained. It is shown that the present chemo-mechanical theory can characterize the chemo-mechanical coupling behavior of intelligent materials.展开更多
Smart hydrogels are environmentally sensitive hydrogels, which can produce a sensitive response to external stimuli, and often exhibit the characteristics of multi filed coupling. In this paper, a hydrogel rod under c...Smart hydrogels are environmentally sensitive hydrogels, which can produce a sensitive response to external stimuli, and often exhibit the characteristics of multi filed coupling. In this paper, a hydrogel rod under chemomechanical coupling was analytically studied based on a poroelastical model. The already known constitutive and governing equations were simplified into the one dimensional case, then two different boundary conditions were considered. The expressions of concentration, displacement,chemical potential and stress related to time were obtained in a series form. Examples illustrate the interaction mechanism of chemical and mechanical effect. It was found that there was a balance state in the diffusion of concentration and the diffusion process could lead to the expansion or the stress change of the hydrogel rod.展开更多
Electrode is a key component to remain durability and safety of lithium-ion（Li-ion） batteries. Li-ion insertion/removal and thermal expansion mismatch may induce high stress in electrode during charging and discharg...Electrode is a key component to remain durability and safety of lithium-ion（Li-ion） batteries. Li-ion insertion/removal and thermal expansion mismatch may induce high stress in electrode during charging and discharging processes. In this paper, we present a continuum model based on COMSOL Multiphysics software, which involves thermal, chemical and mechanical behaviors of electrodes. The results show that,because of diffusion-induced stress and thermal mismatch, the electrode geometry plays an important role in diffusion kinetics of Li-ions. A higher local compressive stress results in a lower Li-ion concentration and thus a lower capacity when a particle is embedded another, which is in agreement with experimental observations.展开更多
We studied the corrosion characteristics of reinforcing bars in concrete under different corrosion conditions. The area-box （AB） value was used to classify the shape of pitting corrosion morphology in meso-scale, an...We studied the corrosion characteristics of reinforcing bars in concrete under different corrosion conditions. The area-box （AB） value was used to classify the shape of pitting corrosion morphology in meso-scale, and fractographs of reinforcing bars with different corrosion morphology were discussed in micro- and macro-scales. The results show that the existence of the tensile stress affects the corrosion characteristics of reinforcing bars. The pitting morphology and fractograph of reinforcing bars exhibit a statistical fractal feature. The linear regression model fits the relationship between fractal dimensions of corrosion morphology and fractal dimension of fractograph fairly well. Using fractal dimension as the characterization parameter can not only reflect the characteristics of pitting corrosion morphology in reinforcing bars, but also reveal the fracture feature of corroded reinforcing bars.展开更多
Tin (Sn) metal foil is a promising anode for next-generation high-energy–density lithium-ion batteries (LIBs) due to its high capacity and easy processibility. However, the pristine Sn foil anode suffers nonuniform a...Tin (Sn) metal foil is a promising anode for next-generation high-energy–density lithium-ion batteries (LIBs) due to its high capacity and easy processibility. However, the pristine Sn foil anode suffers nonuniform alloying/dealloying reaction with lithium (Li) and huge volume variation, leading to electrode pulverization and inferior electrochemical performance. Herein, we proposed that reduced grain size and elaborate porosity design of Sn foil can circumvent the nonuniform alloy reaction and buffer the volume change during the lithiation/delithiation cycling. Experimentally, we designed a three-dimensional interconnected porous Sn (3DIP-Sn) foil by a facile chemical alloying/dealloying approach, which showed improved electrochemical performance. The enhanced structure stability of the as-fabricated 3DIP-Sn foil was verified by chemo-mechanical simulations and experimental investigation. As expected, the 3DIP-Sn foil anode revealed a long cycle lifespan of 4400 h at 0.5 mA cm^(−2) and 1 mAh cm^(−2) in Sn||Li half cells. A 3DIP-Sn||LiFePO_(4) full cell with LiFePO_(4) loading of 7.1 mg cm^(−2) exhibited stable cycling for 500 cycles with 80% capacity retention at 70 mA g^(−1). Pairing with high-loading commercial LiNi0.6Co0.2Mn0.2O_(2) (NCM622, 18.4 mg cm^(−2)) cathode, a 3DIP-Sn||NCM622 full cell delivered a high reversible capacity of 3.2 mAh cm^(−2). These results demonstrated the important role of regulating the uniform alloying/dealloying reaction and circumventing the localized strain/stress in improving the electrochemical performance of Sn foil anodes for advanced LIBs.展开更多
Phase transition of hydrogel,which is polymerized by polymer network,can be regarded as the transition of polymer network stability.The stability of the polymer network might be changed when the external environment c...Phase transition of hydrogel,which is polymerized by polymer network,can be regarded as the transition of polymer network stability.The stability of the polymer network might be changed when the external environment changed.This change will lead to the transformation of sensitive hydrogels stability,thus phase transition of hydrogel take place.Here,we present a new free density energy function,which considers the non-gaussianity of the polymer network,chains entanglement and functionality of junctions through adding Gent hyplastic model and Edwards-Vilgis slip-link model to Flory-Huggins theory.A program to calculate the phase transition temperature was written based on new free energy function.Taking PNIPAM hydrogel as an example,the effects of network entanglement on the phase transition temperature of hydrogel were studied by analyzing the microstructure parameters of the hydrogel networks.Analytical results suggest a significant relationship between phase transition temperature and entanglement network.展开更多
Cadmium zinc telluride (CdZnTe) semiconductor has applications in the detection of X-rays and gamma-rays at room temperature without having to use a cooling system. Chemical etching and chemo-mechanical polishing are ...Cadmium zinc telluride (CdZnTe) semiconductor has applications in the detection of X-rays and gamma-rays at room temperature without having to use a cooling system. Chemical etching and chemo-mechanical polishing are processes used to smoothen CdZnTe wafer during detector device fabrication. These processes reduce surface damages left after polishing the wafers. In this paper, we compare the effects of etching and chemo-mechanical polishing on CdZnTe nuclear detectors, using a solution of hydrogen bromide in hydrogen peroxide and ethylene glycol mixture. X-ray photoelectron spectroscopy (XPS) was used to monitor TeO2 on the wafer surfaces. Current-voltage and detector-response measurements were made to study the electrical properties and energy resolution. XPS results showed that the chemical etching process resulted in the formation of more TeO2 on the detector surfaces compared to chemo-mechanical polishing. The electrical resistivity of the detector is of the order of 1010 Ω-cm. The chemo-mechanical polishing process increased the leakage current more that chemical etching. For freshly treated surfaces, the etching process is more detrimental to the energy resolution compared to chemo-mechanically polishing.展开更多
In this paper,by introducing a chemical field,the J-integral formulation is presented for the chemo-mechanical coupled medium based on the laws of thermodynamics.A finite element implementation of the J-integral was p...In this paper,by introducing a chemical field,the J-integral formulation is presented for the chemo-mechanical coupled medium based on the laws of thermodynamics.A finite element implementation of the J-integral was performed to study the mode I chemo-mechanical coupled fracture problem.For derivation of the coupled J-integral,the equivalent domain integral(EDI)method was applied to obtain the mode I J-integral,with expression of the area integrals based on constitutive relationships of a linear elastic small deformation for chemo-mechanical coupling,instead of the finite deformation problem.A finite element procedure is developed to compute the mode I J-integral,and numerical simulation of the y-direction stress field is studied by a subroutine UEL(User defined element)developed in ABAQUS software.Accuracy of the numerical results obtained using the mode I J-integral was verified by comparing them to a well-established model based on linear elastic fracture mechanics(LEFM).Furthermore,a numerical example was presented to illustrate path-independence of the formulated J-integral for a chemo-mechanical coupled specimen under different boundary conditions,showing a high accuracy and reliability of the present method.The variation laws of J-integral and the y-direction stress field with external chemical,mechanical loading and time are revealed.The J-integral value increases with larger external concentration loading in the same integral domain.The extent of diffusion is much greater with larger concentration,which leads to a stronger coupling effect due to the chemical field.This work provides new insights into the fracture mechanics for the chemo-mechanical coupled medium.展开更多
Chemo-mechanical coupling behavior of materials is a transformation process between mechanical and chemical energy.In this paper,based on the coupled chemo-mechanical constitutive equations and governing equations dur...Chemo-mechanical coupling behavior of materials is a transformation process between mechanical and chemical energy.In this paper,based on the coupled chemo-mechanical constitutive equations and governing equations during isothermal process,the equivalent integral forms of chemo-mechanical coupling governing equations and corresponding finite element procedure are obtained by using Hamilton’s principle.An isoparametric plane element for chemo-mechanical coupling is associated into ABAQUS finite element package through user element subroutine UEL.The numerical examples exhibit that the ionic concentration variation can cause mechanical deformation and mechanical action can produce redistribution of ionic concentration for hydrogels.It is proved that the present developed chemo-mechanical coupling finite element procedure can be utilized to model the coupling behavior of hydrogels effectively.展开更多
Microfluidic devices have become a powerful tool for chemical and biologic applications.To control different functional parts on the microchip,valve plays a key role in the device.In conventional methods,physio-mechan...Microfluidic devices have become a powerful tool for chemical and biologic applications.To control different functional parts on the microchip,valve plays a key role in the device.In conventional methods,physio-mechanical valves are usually used on microfluidic chip.Herein,we reported a chemo-mechanical switchable valve on microfluidic chip by using a thermally responsive block copolymer.The wettability changes of capillary with copolymer modification on inner surface were investigated to verify the function as a valve.Capillaries with modification of poly-(N-isopropylacrylamide-co-hexafluoroisopropyl acrylate)(P(NIPAAm-co-HFIPA))with a 20%HFIPA was demonstrated capable of control aqueous solution stop or go through.Then short capillaries with copolymer modification were integrated in microchannels as valves.With the temperature changing around lower critical solution temperature(LCST),the integrated chemo-mechanical switchable valve exhibited excellent“OPEN–CLOSE”behavior for microflow control.After optimization of the block copolymer sequences and molar ratio,a switching time as low as 20 s was achieved.The developed micro valve was demonstrated effective for flow control on microchip.展开更多
Fracture analysis of a plane crack problem under chemo-mechanical loading is presented based on a linear chemo-elasticity model.The flux conductivity is introduced to characterize the influence of the crack defect on ...Fracture analysis of a plane crack problem under chemo-mechanical loading is presented based on a linear chemo-elasticity model.The flux conductivity is introduced to characterize the influence of the crack defect on the diffusion process.Using Fourier transform and the dislocation density functions,the crack problem is reduced to a set of singular integral equations,which are solved numerically by the Lobatto-Chebyshev method.Parametric studies are conducted to reveal the effects of flux conductivity,geometric configuration,chemical and mechanical loads on the crack tip field.The numerical results show that the stress singularity at the crack tip is usually a mixture of mode Ⅰ and mode Ⅱ types.展开更多
In the French concept of deep nuclear wastes repository, the galleries should be backfilled with excavated argillite after the site exploitation period. After several thousands of years, the degradation of the concret...In the French concept of deep nuclear wastes repository, the galleries should be backfilled with excavated argillite after the site exploitation period. After several thousands of years, the degradation of the concrete lining of the galleries will generate alkaline fluid (pH 】 12) that will diffuse through the backfill. The objective of the paper is to describe the influence of such solute diffusion on the microstructure and the mechanical behavior of compacted argillite. Saturated-portlandite water was circulated through compacted samples for 3, 6 and 12 months at 20 °C or 60 °C, respectively. The microstructures before and after fluid circulation were determined with mercury intrusion porosimetry. Since it was planned to introduce additives (bentonite or lime) in the remoulded argillite to backfill the deep galleries, such mixtures were also studied. The results show that the influence of the alkaline fluid on the properties of the argillite is a function of the nature of the additive. The pure argillite undergoes slight modifications that can be related to a limited dissolution of its clayey particles. Conversely, intense alteration of the bentonite-argillite mixture was observed. Lime addition improves the mechanical characteristics of the argillite through the precipitation of cementitious compounds.展开更多
The nickel-rich layered ternary cathode material(NCM)has been extensively studied due to its high specific capacity and low cost.Nevertheless,with the increase of Ni content,the unstable structure of NCM material has ...The nickel-rich layered ternary cathode material(NCM)has been extensively studied due to its high specific capacity and low cost.Nevertheless,with the increase of Ni content,the unstable structure of NCM material has gradually become prominent.Residual alkali on the surface and Li^(+)/Ni^(2+)mixing before cycling,phase change,transition metal ions dissolution,microcracking,and other issues during the cycle,are the primary causes for the fast capacity fading of Ni-rich materials.In this study,Sc^(3+)is doped into the LiNi_(0.8)Co_(0.1)Mn_(0.1)0_(2) material,which has been demonstrated to impede the Li^(+)/Ni^(2+)mixing,while simultaneously increasing the layer spacing.This results in the stabilization of the material structure and an enhancement of both the cycling stability and the rate performance.Notably,single-particle force testing and high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM)imaging further demonstrate reduced stress accumulation and mitigated chemo-mechanical failure.This study underscores the efficacy of a minor addition of multifunctional rare-earth doping in enhancing the chemo-mechanical stability of Ni-rich cathodes,offering a straightforward and comprehensive solution to optimize the design and performance of energy storage cathodes.展开更多
Solid-state batteries(SSBs)are attracting growing interest as long-lasting,thermally resilient,and high-safe energy storage systems.As an emerging area of battery chemistry,there are many issues with SSBs,including st...Solid-state batteries(SSBs)are attracting growing interest as long-lasting,thermally resilient,and high-safe energy storage systems.As an emerging area of battery chemistry,there are many issues with SSBs,including strongly reductive lithium anodes,oxidized cathodes(state of charge),the thermodynamic stability limits of solid-state electrolytes(SSEs),and the ubiquitous and critical interfaces.In this Review,we provided an overview of the main obstacles in the development of SSBs,such as the lithium anode|SSEs interface,the cathode|SSEs interface,lithium-ion transport in the SSEs,and the root origin of lithium intrusions,as well as the safety issues caused by the dendrites.Understanding and overcoming these obstacles are crucial but also extremely challenging as the localized and buried nature of the intimate contact between electrode and SSEs makes direct detection difficult.We reviewed advanced characterization techniques and discussed the complex ion/electron-transport mechanism that have been plaguing electrochemists.Finally,we focused on studying and revealing the coupled electro-chemo-mechanical behavior occurring in the lithium anode,cathode,SSEs,and beyond.展开更多
Multi-scale chemo-mechanical effects and microscopic failure modes are explored in the evolution of strength change of slip surface. Direct shear equipments, scanning electro-microscope and X-ray diffraction are used ...Multi-scale chemo-mechanical effects and microscopic failure modes are explored in the evolution of strength change of slip surface. Direct shear equipments, scanning electro-microscope and X-ray diffraction are used to trace the change in strength of remodeled soils of slip surfaces in the Three Gorges area. Results show that there is a release of alkali metals and concentration of clay minerals on the surface. During the tests, potassium ions were released, the cementation was reduced, and the ratio of interlayer minerals varied associated with strength change. Accordingly, illites or montmorillonite-illite mixtures turned into montmorillonite. So the strength change originates from the release of alkali metal ions on molecular scale that leads to the concentration and transition of clay minerals on meso-scale. The evolution of slip surface and soil strength is a typical process involving multi-scale processes of structure changes and chemo-mechanical coupling.展开更多
The metal materials are susceptible to be oxidized when they are exposed to the complex and harsh environments, especially at the elevated temperature. The development of corresponding chemo-mechanical coupling theory...The metal materials are susceptible to be oxidized when they are exposed to the complex and harsh environments, especially at the elevated temperature. The development of corresponding chemo-mechanical coupling theory is indispensable in theoretically and numerically predicting the material properties reduction and failures due to the oxidation. In this paper, we review the historical sketch of the coupling theory of chemical reactions and mechanics in the high-temperature oxidation of metal materials. The oxidation results in the stress generation while the generated stress in turn affects the chemical reaction rate and the diffusion process of the reactants. It is therefore a complex chemo-mechanical coupling problem. This review begins with the discussion of the diffusion-controlled oxidation, and then discusses the stress-dependent diffussion during the oxidation and the oxide growth induced stress, and ends with the discussion of interaction between chemical reactions and stress. This review of chemo-mechanical coupling literature is not exhaustive;we review much of the fundamental literature and draw comparisons of coupling theory development in the filed of metal oxidation.展开更多
The rapid development in the field of chemo-mechanical coupling has drawn increasing attention in recent years. Chemomechanical coupling phenomena exist in many research areas, ranging from development of advanced bat...The rapid development in the field of chemo-mechanical coupling has drawn increasing attention in recent years. Chemomechanical coupling phenomena exist in many research areas, ranging from development of advanced batteries, biomechanical engineering, hydrogen embrittlement, and high temperature oxidation, etc. In this review, we attempt to provide an overview of the recent advances in chemo-mechanical coupling study on high temperature oxidation. The theoretical frameworks, computational modeling, and experimental studies on this subject are summarized and discussed. The stress-diffusion coupling effect in diffusion-controlled oxidation process, stress-induced evolution of oxide morphology in microscale experiment, and stressoxidation interaction at crack front for intergranular fracture are highlighted. In addition, potential applications and possible methods via surface engineering for improving oxidation-resistance of high temperature structural materials are briefly discussed.展开更多
The insertion and extraction of lithium ions in active materials lead to significant volumetric deformation,resulting in stresses that drive the mechanical degradation of these materials.This accumulation of mechanica...The insertion and extraction of lithium ions in active materials lead to significant volumetric deformation,resulting in stresses that drive the mechanical degradation of these materials.This accumulation of mechanical degradation ultimately leads to mechanical failure in lithium-ion batteries(LIB).This paper summarizes the experimental characterization techniques used to observe the mechanical degradation of lithium battery cells,electrodes,and particles across macro,micro,and nano scales.Additionally,the mechanical failure model for LIB that spans from the microscopic to the macroscopic scale has been outlined.Finally,we analyze the current challenges and opportunities,including the standardization of battery measurements,the quantification of mechanical failures,and the correlation between mechanical failures and electrochemical performance.展开更多
基金supported by the National Natural Science Foundation of China(Project No.12102305)the Fundamental Research Funds for the Central Universities.
文摘The microstructure of positive electrode polycrystalline particles(secondary particles)directly affects their diffusion and mechanical properties.In this study,a quantitative evaluation of the effects of grain anisotropy on the overall diffusion and mechanical properties of secondary particles is conducted,which is based on a simplified 2D polycrystalline model with hexagonal anisotropic grains(primary particles)with different distributed orientations.The research results indicate that consistent grain orientation can promote the uniform distribution of lithium ions,while lower diffusion anisotropy can promote the diffusion of lithium ions along shorter paths,thereby improving the diffusion properties of secondary particles.Lower elastic anisotropy of grains and a grain orientation distribution with a 60°angle favor maintaining the macroscopic elastic isotropy of secondary particles.The study also found that when the number of grains is large enough and the orientation distribution is sufficiently random,secondary particles exhibit macroscopic diffusion isotropy and elastic isotropy.
基金Ministry of Education,Culture,Research and Technology(KEMENDIKBUDRISTEK)Republic of Indonesia,for providing the Research Grant“Basic Research Scheme”No.110/E5/PG.02.00.PL/2023.
文摘The present work emphasizes the isolation of cellulose nanofiber(CNF)from the kenaf(Hibiscus cannabinus)bast through a chemo-mechanical process.In order to develop high CNF yield with superior properties of CNF for improving compatibility in varied applications this method is proposed.The fiber purification involved pulping and bleaching treatments,whereas mechanical treatment was performed by grinding and high-pressure treatments.The kraft pulping as a delignification method followed by bleaching has successfully removed almost 99%lignin in the fiber with high pulp yield and delignification selectivity.The morphology of the fibers was characterized by scanning electron microscopy,which showed a smooth surface,fiber bundles,gel-shaped nanofiber,and an average size of 94.05 nm with 69%of CNF in 34–100 nm size.The chemo-mechanical process exhibited a more crystalline nature in CNF than pulp kenaf.The low zeta potential values exhibit the distribution of fibrils and colloidal suspension stability without any further agglomeration.A lower concentration of CNF is less stable exhibiting the product agglomeration.Therefore,the chemo-mechanical process for the isolation of CNF(Hibiscus cannabinus)from kenaf involves sustainable,low-cost,non-toxic,and cheap alternatives than other traditional methods.
基金The project supported by the National Natural Science Foundation of China(Nos.10872011 and 11172012)the Municipal Natural Science Foundation of Beijing(No.3092006)
文摘Chemo-mechanical coupling exists in a lot of intelligent materials including hy- drogels, biological tissues and other soft materials. These materials are able to respond to ex- ternal stimulus, such as temperature, chemical concentration, and pH value. In this paper, a one-dimensional theoretical model for chemo-mechanical coupling is proposed for analyzing the uniaxial stress/strain state of coupling materials. Based on the chemo-mechanical coupled gov- erning equation, the displacement function and concentration function are derived and the stress and chemical potential are obtained. It is shown that the present chemo-mechanical theory can characterize the chemo-mechanical coupling behavior of intelligent materials.
基金financial supports from the National Natural Science Foundation of China (Grants 11472020, 11502007, and 11632005)Hong Kong Scholars Program (Grant XJ2016021)
文摘Smart hydrogels are environmentally sensitive hydrogels, which can produce a sensitive response to external stimuli, and often exhibit the characteristics of multi filed coupling. In this paper, a hydrogel rod under chemomechanical coupling was analytically studied based on a poroelastical model. The already known constitutive and governing equations were simplified into the one dimensional case, then two different boundary conditions were considered. The expressions of concentration, displacement,chemical potential and stress related to time were obtained in a series form. Examples illustrate the interaction mechanism of chemical and mechanical effect. It was found that there was a balance state in the diffusion of concentration and the diffusion process could lead to the expansion or the stress change of the hydrogel rod.
基金supported by the National Natural Science Foundation of China (11702234 and 11602213)
文摘Electrode is a key component to remain durability and safety of lithium-ion（Li-ion） batteries. Li-ion insertion/removal and thermal expansion mismatch may induce high stress in electrode during charging and discharging processes. In this paper, we present a continuum model based on COMSOL Multiphysics software, which involves thermal, chemical and mechanical behaviors of electrodes. The results show that,because of diffusion-induced stress and thermal mismatch, the electrode geometry plays an important role in diffusion kinetics of Li-ions. A higher local compressive stress results in a lower Li-ion concentration and thus a lower capacity when a particle is embedded another, which is in agreement with experimental observations.
基金Funded by 973 Program(No.2009CB623200)National Natural Science Foundation of China(No.51008276)+1 种基金Ningbo Scientific and Technological Innovation Team(No.2011B81005)Ningbo Natural Science Foundation(No.2011A610075)
文摘We studied the corrosion characteristics of reinforcing bars in concrete under different corrosion conditions. The area-box （AB） value was used to classify the shape of pitting corrosion morphology in meso-scale, and fractographs of reinforcing bars with different corrosion morphology were discussed in micro- and macro-scales. The results show that the existence of the tensile stress affects the corrosion characteristics of reinforcing bars. The pitting morphology and fractograph of reinforcing bars exhibit a statistical fractal feature. The linear regression model fits the relationship between fractal dimensions of corrosion morphology and fractal dimension of fractograph fairly well. Using fractal dimension as the characterization parameter can not only reflect the characteristics of pitting corrosion morphology in reinforcing bars, but also reveal the fracture feature of corroded reinforcing bars.
基金This work is financially supported by the National Natural Science Foundation of China(Grant Nos.52072137,51802105).
文摘Tin (Sn) metal foil is a promising anode for next-generation high-energy–density lithium-ion batteries (LIBs) due to its high capacity and easy processibility. However, the pristine Sn foil anode suffers nonuniform alloying/dealloying reaction with lithium (Li) and huge volume variation, leading to electrode pulverization and inferior electrochemical performance. Herein, we proposed that reduced grain size and elaborate porosity design of Sn foil can circumvent the nonuniform alloy reaction and buffer the volume change during the lithiation/delithiation cycling. Experimentally, we designed a three-dimensional interconnected porous Sn (3DIP-Sn) foil by a facile chemical alloying/dealloying approach, which showed improved electrochemical performance. The enhanced structure stability of the as-fabricated 3DIP-Sn foil was verified by chemo-mechanical simulations and experimental investigation. As expected, the 3DIP-Sn foil anode revealed a long cycle lifespan of 4400 h at 0.5 mA cm^(−2) and 1 mAh cm^(−2) in Sn||Li half cells. A 3DIP-Sn||LiFePO_(4) full cell with LiFePO_(4) loading of 7.1 mg cm^(−2) exhibited stable cycling for 500 cycles with 80% capacity retention at 70 mA g^(−1). Pairing with high-loading commercial LiNi0.6Co0.2Mn0.2O_(2) (NCM622, 18.4 mg cm^(−2)) cathode, a 3DIP-Sn||NCM622 full cell delivered a high reversible capacity of 3.2 mAh cm^(−2). These results demonstrated the important role of regulating the uniform alloying/dealloying reaction and circumventing the localized strain/stress in improving the electrochemical performance of Sn foil anodes for advanced LIBs.
基金support from the National Natural Science Foundation of China(Grant Nos.11520007,11572109 and 11632005)the Hebei Natural Science Foundation of China(Grant No.A2016201198)technology research in Colleges and Universities of Hebei Province(Grant No.ZD2017006)are gratefully acknowledged。
文摘Phase transition of hydrogel,which is polymerized by polymer network,can be regarded as the transition of polymer network stability.The stability of the polymer network might be changed when the external environment changed.This change will lead to the transformation of sensitive hydrogels stability,thus phase transition of hydrogel take place.Here,we present a new free density energy function,which considers the non-gaussianity of the polymer network,chains entanglement and functionality of junctions through adding Gent hyplastic model and Edwards-Vilgis slip-link model to Flory-Huggins theory.A program to calculate the phase transition temperature was written based on new free energy function.Taking PNIPAM hydrogel as an example,the effects of network entanglement on the phase transition temperature of hydrogel were studied by analyzing the microstructure parameters of the hydrogel networks.Analytical results suggest a significant relationship between phase transition temperature and entanglement network.
文摘Cadmium zinc telluride (CdZnTe) semiconductor has applications in the detection of X-rays and gamma-rays at room temperature without having to use a cooling system. Chemical etching and chemo-mechanical polishing are processes used to smoothen CdZnTe wafer during detector device fabrication. These processes reduce surface damages left after polishing the wafers. In this paper, we compare the effects of etching and chemo-mechanical polishing on CdZnTe nuclear detectors, using a solution of hydrogen bromide in hydrogen peroxide and ethylene glycol mixture. X-ray photoelectron spectroscopy (XPS) was used to monitor TeO2 on the wafer surfaces. Current-voltage and detector-response measurements were made to study the electrical properties and energy resolution. XPS results showed that the chemical etching process resulted in the formation of more TeO2 on the detector surfaces compared to chemo-mechanical polishing. The electrical resistivity of the detector is of the order of 1010 Ω-cm. The chemo-mechanical polishing process increased the leakage current more that chemical etching. For freshly treated surfaces, the etching process is more detrimental to the energy resolution compared to chemo-mechanically polishing.
基金This work was supported by the National Natural Science Foundation of China under grant numbers 11472020,11502007,11632005,which is gratefully acknowledged.
文摘In this paper,by introducing a chemical field,the J-integral formulation is presented for the chemo-mechanical coupled medium based on the laws of thermodynamics.A finite element implementation of the J-integral was performed to study the mode I chemo-mechanical coupled fracture problem.For derivation of the coupled J-integral,the equivalent domain integral(EDI)method was applied to obtain the mode I J-integral,with expression of the area integrals based on constitutive relationships of a linear elastic small deformation for chemo-mechanical coupling,instead of the finite deformation problem.A finite element procedure is developed to compute the mode I J-integral,and numerical simulation of the y-direction stress field is studied by a subroutine UEL(User defined element)developed in ABAQUS software.Accuracy of the numerical results obtained using the mode I J-integral was verified by comparing them to a well-established model based on linear elastic fracture mechanics(LEFM).Furthermore,a numerical example was presented to illustrate path-independence of the formulated J-integral for a chemo-mechanical coupled specimen under different boundary conditions,showing a high accuracy and reliability of the present method.The variation laws of J-integral and the y-direction stress field with external chemical,mechanical loading and time are revealed.The J-integral value increases with larger external concentration loading in the same integral domain.The extent of diffusion is much greater with larger concentration,which leads to a stronger coupling effect due to the chemical field.This work provides new insights into the fracture mechanics for the chemo-mechanical coupled medium.
基金The financial support from the National Natural Science Foundation of China under grants#11172012,#11472020 is gratefully acknowledged.
文摘Chemo-mechanical coupling behavior of materials is a transformation process between mechanical and chemical energy.In this paper,based on the coupled chemo-mechanical constitutive equations and governing equations during isothermal process,the equivalent integral forms of chemo-mechanical coupling governing equations and corresponding finite element procedure are obtained by using Hamilton’s principle.An isoparametric plane element for chemo-mechanical coupling is associated into ABAQUS finite element package through user element subroutine UEL.The numerical examples exhibit that the ionic concentration variation can cause mechanical deformation and mechanical action can produce redistribution of ionic concentration for hydrogels.It is proved that the present developed chemo-mechanical coupling finite element procedure can be utilized to model the coupling behavior of hydrogels effectively.
基金JSPS KAKENHI Grants(Nos.JP21K14653,JP20K22555 and JP20K05557)。
文摘Microfluidic devices have become a powerful tool for chemical and biologic applications.To control different functional parts on the microchip,valve plays a key role in the device.In conventional methods,physio-mechanical valves are usually used on microfluidic chip.Herein,we reported a chemo-mechanical switchable valve on microfluidic chip by using a thermally responsive block copolymer.The wettability changes of capillary with copolymer modification on inner surface were investigated to verify the function as a valve.Capillaries with modification of poly-(N-isopropylacrylamide-co-hexafluoroisopropyl acrylate)(P(NIPAAm-co-HFIPA))with a 20%HFIPA was demonstrated capable of control aqueous solution stop or go through.Then short capillaries with copolymer modification were integrated in microchannels as valves.With the temperature changing around lower critical solution temperature(LCST),the integrated chemo-mechanical switchable valve exhibited excellent“OPEN–CLOSE”behavior for microflow control.After optimization of the block copolymer sequences and molar ratio,a switching time as low as 20 s was achieved.The developed micro valve was demonstrated effective for flow control on microchip.
基金supported by the National Natural Science Foundation of China(Grant Nos.11932005 and 11772106).
文摘Fracture analysis of a plane crack problem under chemo-mechanical loading is presented based on a linear chemo-elasticity model.The flux conductivity is introduced to characterize the influence of the crack defect on the diffusion process.Using Fourier transform and the dislocation density functions,the crack problem is reduced to a set of singular integral equations,which are solved numerically by the Lobatto-Chebyshev method.Parametric studies are conducted to reveal the effects of flux conductivity,geometric configuration,chemical and mechanical loads on the crack tip field.The numerical results show that the stress singularity at the crack tip is usually a mixture of mode Ⅰ and mode Ⅱ types.
基金Supported by the Agence Nationale Pour la Gestion des Déchets Radioactifs (026350SMG)
文摘In the French concept of deep nuclear wastes repository, the galleries should be backfilled with excavated argillite after the site exploitation period. After several thousands of years, the degradation of the concrete lining of the galleries will generate alkaline fluid (pH 】 12) that will diffuse through the backfill. The objective of the paper is to describe the influence of such solute diffusion on the microstructure and the mechanical behavior of compacted argillite. Saturated-portlandite water was circulated through compacted samples for 3, 6 and 12 months at 20 °C or 60 °C, respectively. The microstructures before and after fluid circulation were determined with mercury intrusion porosimetry. Since it was planned to introduce additives (bentonite or lime) in the remoulded argillite to backfill the deep galleries, such mixtures were also studied. The results show that the influence of the alkaline fluid on the properties of the argillite is a function of the nature of the additive. The pure argillite undergoes slight modifications that can be related to a limited dissolution of its clayey particles. Conversely, intense alteration of the bentonite-argillite mixture was observed. Lime addition improves the mechanical characteristics of the argillite through the precipitation of cementitious compounds.
基金supported by National Natural Science Foundation of China(22179008,21875022)Yibin Jie Bang Gua Shuai(2022JB004)+2 种基金L.Chen acknowledges the support from Beijing Nova Program(20230484241)J.Y.Dong acknowledges the support from the China Postdoctoral Science Foundation(2024M754084)the Special Support of Chongqing Postdoctoral Research Project(2023CQBSHTB2041).
文摘The nickel-rich layered ternary cathode material(NCM)has been extensively studied due to its high specific capacity and low cost.Nevertheless,with the increase of Ni content,the unstable structure of NCM material has gradually become prominent.Residual alkali on the surface and Li^(+)/Ni^(2+)mixing before cycling,phase change,transition metal ions dissolution,microcracking,and other issues during the cycle,are the primary causes for the fast capacity fading of Ni-rich materials.In this study,Sc^(3+)is doped into the LiNi_(0.8)Co_(0.1)Mn_(0.1)0_(2) material,which has been demonstrated to impede the Li^(+)/Ni^(2+)mixing,while simultaneously increasing the layer spacing.This results in the stabilization of the material structure and an enhancement of both the cycling stability and the rate performance.Notably,single-particle force testing and high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM)imaging further demonstrate reduced stress accumulation and mitigated chemo-mechanical failure.This study underscores the efficacy of a minor addition of multifunctional rare-earth doping in enhancing the chemo-mechanical stability of Ni-rich cathodes,offering a straightforward and comprehensive solution to optimize the design and performance of energy storage cathodes.
基金Talent Scientific Research Project of Qilu University of Technology,Grant/Award Number:2023RCKY181Natural Science Foundation of Shandong Province Youth Project,Grant/Award Number:ZR2022QB178 ZR2020QB197+3 种基金National Natural Science Foundation of China,Grant/Award Numbers:52272136,22108135Natural Science Foundation of Jiangsu province,Grant/Award Number:BK20221402Special Support of China Postdoctoral Science Founudation,Grant/Award Number:2023T160471Basic Research Project of Science,Education and Production Integration Pilot Project。
文摘Solid-state batteries(SSBs)are attracting growing interest as long-lasting,thermally resilient,and high-safe energy storage systems.As an emerging area of battery chemistry,there are many issues with SSBs,including strongly reductive lithium anodes,oxidized cathodes(state of charge),the thermodynamic stability limits of solid-state electrolytes(SSEs),and the ubiquitous and critical interfaces.In this Review,we provided an overview of the main obstacles in the development of SSBs,such as the lithium anode|SSEs interface,the cathode|SSEs interface,lithium-ion transport in the SSEs,and the root origin of lithium intrusions,as well as the safety issues caused by the dendrites.Understanding and overcoming these obstacles are crucial but also extremely challenging as the localized and buried nature of the intimate contact between electrode and SSEs makes direct detection difficult.We reviewed advanced characterization techniques and discussed the complex ion/electron-transport mechanism that have been plaguing electrochemists.Finally,we focused on studying and revealing the coupled electro-chemo-mechanical behavior occurring in the lithium anode,cathode,SSEs,and beyond.
基金supported by the National Natural Science Foundation of China (Grant No. 40171005)the Key Project of National Natural Science Foundation of China (Grant No. 41030742)+1 种基金Foundation of Key Laboratory of Mountain Hazards and Earth Surface Process of Chinese Academy of Sciencesthe Natural Science Foundation of U.S.A. (Grant No. 0324543)
文摘Multi-scale chemo-mechanical effects and microscopic failure modes are explored in the evolution of strength change of slip surface. Direct shear equipments, scanning electro-microscope and X-ray diffraction are used to trace the change in strength of remodeled soils of slip surfaces in the Three Gorges area. Results show that there is a release of alkali metals and concentration of clay minerals on the surface. During the tests, potassium ions were released, the cementation was reduced, and the ratio of interlayer minerals varied associated with strength change. Accordingly, illites or montmorillonite-illite mixtures turned into montmorillonite. So the strength change originates from the release of alkali metal ions on molecular scale that leads to the concentration and transition of clay minerals on meso-scale. The evolution of slip surface and soil strength is a typical process involving multi-scale processes of structure changes and chemo-mechanical coupling.
基金the gratitude for the support of National Natural Science Foundation of China (Grant No. 11632014)the Chang Jiang Scholar Program, and the “111” Project (Grant No. B18040)+1 种基金the support of National Natural Science Foundation of China (Grant Nos. 11502191, 11872049)the support by the Fundamental Research Funds for the Central Universities, CHD (Grant No. 300102289302)
文摘The metal materials are susceptible to be oxidized when they are exposed to the complex and harsh environments, especially at the elevated temperature. The development of corresponding chemo-mechanical coupling theory is indispensable in theoretically and numerically predicting the material properties reduction and failures due to the oxidation. In this paper, we review the historical sketch of the coupling theory of chemical reactions and mechanics in the high-temperature oxidation of metal materials. The oxidation results in the stress generation while the generated stress in turn affects the chemical reaction rate and the diffusion process of the reactants. It is therefore a complex chemo-mechanical coupling problem. This review begins with the discussion of the diffusion-controlled oxidation, and then discusses the stress-dependent diffussion during the oxidation and the oxide growth induced stress, and ends with the discussion of interaction between chemical reactions and stress. This review of chemo-mechanical coupling literature is not exhaustive;we review much of the fundamental literature and draw comparisons of coupling theory development in the filed of metal oxidation.
基金supported by the National Basic Research Program of China(Grant No.2015CB351900)the National Natural Science Foundation of China(Grant Nos.11625207,11320101001,11227801)
文摘The rapid development in the field of chemo-mechanical coupling has drawn increasing attention in recent years. Chemomechanical coupling phenomena exist in many research areas, ranging from development of advanced batteries, biomechanical engineering, hydrogen embrittlement, and high temperature oxidation, etc. In this review, we attempt to provide an overview of the recent advances in chemo-mechanical coupling study on high temperature oxidation. The theoretical frameworks, computational modeling, and experimental studies on this subject are summarized and discussed. The stress-diffusion coupling effect in diffusion-controlled oxidation process, stress-induced evolution of oxide morphology in microscale experiment, and stressoxidation interaction at crack front for intergranular fracture are highlighted. In addition, potential applications and possible methods via surface engineering for improving oxidation-resistance of high temperature structural materials are briefly discussed.
基金funded by the Key Research and Development Project of Guangdong Province(No.2023B0909050004)the National Natural Science Foundation of China(No.12402214).
文摘The insertion and extraction of lithium ions in active materials lead to significant volumetric deformation,resulting in stresses that drive the mechanical degradation of these materials.This accumulation of mechanical degradation ultimately leads to mechanical failure in lithium-ion batteries(LIB).This paper summarizes the experimental characterization techniques used to observe the mechanical degradation of lithium battery cells,electrodes,and particles across macro,micro,and nano scales.Additionally,the mechanical failure model for LIB that spans from the microscopic to the macroscopic scale has been outlined.Finally,we analyze the current challenges and opportunities,including the standardization of battery measurements,the quantification of mechanical failures,and the correlation between mechanical failures and electrochemical performance.
