Sodium metal is one of the ideal anodes for high-performance rechargeable batteries because of its high specific capacity(~1166 mAh·g^(-1)),low reduction potential(-2.71 V compared to standard hydrogen electrodes...Sodium metal is one of the ideal anodes for high-performance rechargeable batteries because of its high specific capacity(~1166 mAh·g^(-1)),low reduction potential(-2.71 V compared to standard hydrogen electrodes),and low cost.However,the unstable solid electrolyte interphase,uncontrolled dendrite growth,and inevitable volume expansion hinder the practical application of sodium metal anodes.At present,many strategies have been developed to achieve stable sodium metal anodes.Here,we systematically summarize the latest strategies adopted in interface engineering,current collector design,and the emerging methods to improve the reaction kinetics of sodium deposition processes.First,the strategies of constructing protective layers are reviewed,including inorganic,organic,and mixed protective layers through electrolyte additives or pretreatments.Then,the classification of metal-based,carbon-based,and composite porous frames is discussed,including their function in reducing local deposition current density and the effect of introducing sodiophilic sites.Third,the recent progress of alloys,nanoparticles,and single atoms in improving Na deposition kinetics is systematically reviewed.Finally,the future research direction and the prospect of high-performance sodium metal batteries are proposed.展开更多
MoS_(2) is a highly promising material for application in lithium-ion battery anodes due to its high theoretical capacity and low cost.However,problems with a fast capacity decay over cycling,especially at the first c...MoS_(2) is a highly promising material for application in lithium-ion battery anodes due to its high theoretical capacity and low cost.However,problems with a fast capacity decay over cycling,especially at the first cycles,and poor rate performance have deterred its practical implementation.Herein,electrodes comprised solely of few-layers 2D MoS_(2) nanosheets have been manufactured by scalable liquid-phase exfoliation and spray deposition methods.The long-standing controversy questioning the reversibility of conversion processes of MoS_(2)-based electrodes was addressed.Raman studies revealed that,in 2D MoS_(2) electrodes,conversion processes are indeed reversible,where nanostructure played a key role.Cycling of the electrodes at high current rates revealed an intriguing phenomenon consisting of a continuously increasing capacity after ca.100-200 cycles.This phenomenon was comprehensively addressed by a variety of electrochemical and microscopy methods that revealed underlying physical activation mechanisms that involved a range of profound electrode structural changes.Activation mechanisms delivered a capacitive electrode of a superior rate performance and cycling stability,as compared to the corresponding pristine electrodes,and to MoS_(2) electrodes previously reported.Herein,we have devised a methodology to overcome the problem of cycling stability of 2D MoS_(2) electrodes.Moreover,activation of electrodes constitutes a methodology that could be applied to enhance the energy storage performance of electrodes based on other 2D nanomaterials,or combinations thereof,strategically combining chemistries to engineer electrodes of superior energy storage properties.展开更多
In the present work we aim to simulate shallow water flows over movable bottom with suspended and bedload transport.In order to numerically approximate such a system,we proceed step by step.We start by considering sha...In the present work we aim to simulate shallow water flows over movable bottom with suspended and bedload transport.In order to numerically approximate such a system,we proceed step by step.We start by considering shallow water equations with non-constant density of the mixture water-sediment.Then,the Exner equation is included to take into account bedload sediment transport.Finally,source terms for friction,erosion and deposition processes are considered.Indeed,observe that the sediment particle could go in suspension into the water or being deposited on the bottom.For the numerical scheme,we rely on well-balanced Lagrange-projection methods.In particular,since sediment transport is generally a slow process,we aim to develop semi-implicit schemes in order to obtain fast simulations.The Lagrange-projection splitting is well-suited for such a purpose as it entails a decomposition of the(fast)acoustic waves and the(slow)material waves of the model.Hence,in subsonic regimes,an implicit approximation of the acoustic equations allows us to neglect the corresponding CFL condition and to obtain fast numerical schemes with large time step.展开更多
The analytic formula of the ionization efficiency in the process of double resonance enhanced multi-photon ionization （DREMPI） is derived from the dynamic rate equation about the interaction of photon and material. ...The analytic formula of the ionization efficiency in the process of double resonance enhanced multi-photon ionization （DREMPI） is derived from the dynamic rate equation about the interaction of photon and material. Based on this formula, the ionization efficiency and the laser power index versus laser intensity in the DREMPI process of NO molecule, via A2E and S2E intermediate resonant states, is numerically simulated. It is shown that the ionization efficiency of NO molecule increases with the laser intensity until getting saturation, while the laser power index decreases with the enhancement of the laser intensity and changes to zero at last. The variation of the laser power index with the laser intensity indicates that the ionization efficiency reaches saturation in the one, two, and three excitation steps respectively. It is also found that the narrower the laser pulse duration is, the higher becomes the laser intensity for saturation.展开更多
An extended one-dimensional stress model for the deposition of multilayer films is built based on the existing stress model by considering the influence of deposition conditions. Both thermal stress and intrinsic stre...An extended one-dimensional stress model for the deposition of multilayer films is built based on the existing stress model by considering the influence of deposition conditions. Both thermal stress and intrinsic stress are considered to constitute the final residual stress in the model. The deposition process conditions such as deposition temperature, oxygen pressure, and film growth rate are correlated to the full stress model to analyze the final residual stress distribution, and thus the deformation of the deposited multilayer system under different process conditions. Also, the model is numerically realized with in-house built code. A deposition of Ag-Cu multilayer system is simulated with the as-built extended stress model, and the final residual stresses under different deposition conditions are discussed with part of the results compared with experiment from other literature.展开更多
AlN thin films were deposited on c-,a-and r-plane sapphire substrates by the magnetron sputtering technique.The in-fluence of high-temperature thermal annealing(HTTA)on the structural,optical properties as well as sur...AlN thin films were deposited on c-,a-and r-plane sapphire substrates by the magnetron sputtering technique.The in-fluence of high-temperature thermal annealing(HTTA)on the structural,optical properties as well as surface stoichiometry were comprehensively investigated.The significant narrowing of the(0002)diffraction peak to as low as 68 arcsec of AlN after HTTA implies a reduction of tilt component inside the AlN thin films,and consequently much-reduced dislocation densities.This is also supported by the appearance of E2(high)Raman peak and better Al-N stoichiometry after HTTA.Furthermore,the in-creased absorption edge after HTTA suggests a reduction of point defects acting as the absorption centers.It is concluded that HTTA is a universal post-treatment technique in improving the crystalline quality of sputtered AlN regardless of sapphire orienta-tion.展开更多
A coupling model between the canopy layer(CL) and atmospheric boundary layer (ABL) for the study of dry deposition velocity is developed. The model consists of six parts: chemical species conservation equation includi...A coupling model between the canopy layer(CL) and atmospheric boundary layer (ABL) for the study of dry deposition velocity is developed. The model consists of six parts: chemical species conservation equation including absorptive factor; the species uptake action including detailed vertical variation of absorptive element in CL; momentum exchange in CL which is represented by a first-order closure momentum equation with an additional larger-scale diffusive term; momentum exchange in ABL which is described by a complete set of the ABL turbulent statistic parameters; absorptivity (or solubility or reflection) at the surface including effects of the physical and chemical characters of the species, land type, seasonal and diurnal variations of the meteorological variables; and deposition velocity derived by distributions of the species with height in CL. Variational rules of the concentration and deposition velocity with both height and time are simulated with the model for both corn and forest canopies. Results predicted with the bulk deposition velocity derived in the paper consist well with experimental data.展开更多
The magnitude of river morphological changes are better analyzed through the use of quantitative approaches, wherein resolution accuracy and uncertainty assessment are treated as crucial key-factors. In this sense, th...The magnitude of river morphological changes are better analyzed through the use of quantitative approaches, wherein resolution accuracy and uncertainty assessment are treated as crucial key-factors. In this sense, the creation of precise DEMs （Digital Elevation Models） of rivers represents an affordable tool to analyze geomorphic variations and budgets, except for wetted areas, where reliable channel digitalization can normally be obtained only using expensive bathymetric surveys. The proposed work aims at improving channel surface models without having available bathymetric sensors, by deriving dry areas elevations from LiDAR data and water depth of wetted areas from aerial photos through a predictive depth-colour relationship. The methodology was applied to two different sub-reaches of the Piave River, a gravel-bed river which suffered severe flood events in 2010. Erosion and deposition patterns were identified through DEM differencing, showing a predominance of scour processes which can lead to channel instability situations. The bathymetric output was compared to other previously-derived models confirming the accuracy of the in-channel elevation estimates. Finally, a discussion on the role played by longitudinal protections during the studied flood events is proposed, focusing the attention on the incidence of two major bank erosions that removed significant volumes of stable areas.展开更多
基金supports from the National Natural Science Foundation of China(No.52002358)high-level talent internationalization training project of Henan province,and scientific and technological activities of Henan Province for scholars with overseas study experience(No.002004025)+1 种基金G.X.W.and B.S.would like to thank the support of the Australian Research Council(ARC)through the ARC Discovery Project(No.DP210101389)ARC Future Fellowship(No.FT220100561).
文摘Sodium metal is one of the ideal anodes for high-performance rechargeable batteries because of its high specific capacity(~1166 mAh·g^(-1)),low reduction potential(-2.71 V compared to standard hydrogen electrodes),and low cost.However,the unstable solid electrolyte interphase,uncontrolled dendrite growth,and inevitable volume expansion hinder the practical application of sodium metal anodes.At present,many strategies have been developed to achieve stable sodium metal anodes.Here,we systematically summarize the latest strategies adopted in interface engineering,current collector design,and the emerging methods to improve the reaction kinetics of sodium deposition processes.First,the strategies of constructing protective layers are reviewed,including inorganic,organic,and mixed protective layers through electrolyte additives or pretreatments.Then,the classification of metal-based,carbon-based,and composite porous frames is discussed,including their function in reducing local deposition current density and the effect of introducing sodiophilic sites.Third,the recent progress of alloys,nanoparticles,and single atoms in improving Na deposition kinetics is systematically reviewed.Finally,the future research direction and the prospect of high-performance sodium metal batteries are proposed.
基金financial support from the China Scholarship Council(CSC grant.201808330389)。
文摘MoS_(2) is a highly promising material for application in lithium-ion battery anodes due to its high theoretical capacity and low cost.However,problems with a fast capacity decay over cycling,especially at the first cycles,and poor rate performance have deterred its practical implementation.Herein,electrodes comprised solely of few-layers 2D MoS_(2) nanosheets have been manufactured by scalable liquid-phase exfoliation and spray deposition methods.The long-standing controversy questioning the reversibility of conversion processes of MoS_(2)-based electrodes was addressed.Raman studies revealed that,in 2D MoS_(2) electrodes,conversion processes are indeed reversible,where nanostructure played a key role.Cycling of the electrodes at high current rates revealed an intriguing phenomenon consisting of a continuously increasing capacity after ca.100-200 cycles.This phenomenon was comprehensively addressed by a variety of electrochemical and microscopy methods that revealed underlying physical activation mechanisms that involved a range of profound electrode structural changes.Activation mechanisms delivered a capacitive electrode of a superior rate performance and cycling stability,as compared to the corresponding pristine electrodes,and to MoS_(2) electrodes previously reported.Herein,we have devised a methodology to overcome the problem of cycling stability of 2D MoS_(2) electrodes.Moreover,activation of electrodes constitutes a methodology that could be applied to enhance the energy storage performance of electrodes based on other 2D nanomaterials,or combinations thereof,strategically combining chemistries to engineer electrodes of superior energy storage properties.
基金supported by the Spanish Government and FEDER through the coordinated Research project RTI2018-096064-B-C1 and PID2022-137637NB-C21the Junta de Andalucía research project P18-RT-3163+2 种基金the Junta de Andalucia-FEDER-University of Málaga research project UMA18-FEDERJA-163the University of Málaga.T.Morales de Luna has been partially supported by the Spanish Government and FEDER through the coordinated Research project RTI2018-096064-B-C2 and PID2022-137637NB-C21by the the Junta de Andalucía research project PROYEXCEL-00525.
文摘In the present work we aim to simulate shallow water flows over movable bottom with suspended and bedload transport.In order to numerically approximate such a system,we proceed step by step.We start by considering shallow water equations with non-constant density of the mixture water-sediment.Then,the Exner equation is included to take into account bedload sediment transport.Finally,source terms for friction,erosion and deposition processes are considered.Indeed,observe that the sediment particle could go in suspension into the water or being deposited on the bottom.For the numerical scheme,we rely on well-balanced Lagrange-projection methods.In particular,since sediment transport is generally a slow process,we aim to develop semi-implicit schemes in order to obtain fast simulations.The Lagrange-projection splitting is well-suited for such a purpose as it entails a decomposition of the(fast)acoustic waves and the(slow)material waves of the model.Hence,in subsonic regimes,an implicit approximation of the acoustic equations allows us to neglect the corresponding CFL condition and to obtain fast numerical schemes with large time step.
基金supported by the National Natural Science Foundation of China (No.10647130)the Doctoral Foundation of North China Electric Power University (No.200612003).
文摘The analytic formula of the ionization efficiency in the process of double resonance enhanced multi-photon ionization （DREMPI） is derived from the dynamic rate equation about the interaction of photon and material. Based on this formula, the ionization efficiency and the laser power index versus laser intensity in the DREMPI process of NO molecule, via A2E and S2E intermediate resonant states, is numerically simulated. It is shown that the ionization efficiency of NO molecule increases with the laser intensity until getting saturation, while the laser power index decreases with the enhancement of the laser intensity and changes to zero at last. The variation of the laser power index with the laser intensity indicates that the ionization efficiency reaches saturation in the one, two, and three excitation steps respectively. It is also found that the narrower the laser pulse duration is, the higher becomes the laser intensity for saturation.
基金supported by the National Natural Science Foundation of China(Grant Nos.51076075,91224008 and 91024032)
文摘An extended one-dimensional stress model for the deposition of multilayer films is built based on the existing stress model by considering the influence of deposition conditions. Both thermal stress and intrinsic stress are considered to constitute the final residual stress in the model. The deposition process conditions such as deposition temperature, oxygen pressure, and film growth rate are correlated to the full stress model to analyze the final residual stress distribution, and thus the deformation of the deposited multilayer system under different process conditions. Also, the model is numerically realized with in-house built code. A deposition of Ag-Cu multilayer system is simulated with the as-built extended stress model, and the final residual stresses under different deposition conditions are discussed with part of the results compared with experiment from other literature.
基金supported by the Youth Innovation Promotion Association of the Chinese Academy of Sciences(2020298)National Key Scientific Instrument and Equipment Development Projects of China(YJKYYQ20190074)+2 种基金National Natural Science Foundation of China(61974149)Primary Research and Development Plan of Zhejiang Province(2020C01145)the Natural Science Foundation of Zhejiang Province(LQ21F040004)。
文摘AlN thin films were deposited on c-,a-and r-plane sapphire substrates by the magnetron sputtering technique.The in-fluence of high-temperature thermal annealing(HTTA)on the structural,optical properties as well as surface stoichiometry were comprehensively investigated.The significant narrowing of the(0002)diffraction peak to as low as 68 arcsec of AlN after HTTA implies a reduction of tilt component inside the AlN thin films,and consequently much-reduced dislocation densities.This is also supported by the appearance of E2(high)Raman peak and better Al-N stoichiometry after HTTA.Furthermore,the in-creased absorption edge after HTTA suggests a reduction of point defects acting as the absorption centers.It is concluded that HTTA is a universal post-treatment technique in improving the crystalline quality of sputtered AlN regardless of sapphire orienta-tion.
文摘A coupling model between the canopy layer(CL) and atmospheric boundary layer (ABL) for the study of dry deposition velocity is developed. The model consists of six parts: chemical species conservation equation including absorptive factor; the species uptake action including detailed vertical variation of absorptive element in CL; momentum exchange in CL which is represented by a first-order closure momentum equation with an additional larger-scale diffusive term; momentum exchange in ABL which is described by a complete set of the ABL turbulent statistic parameters; absorptivity (or solubility or reflection) at the surface including effects of the physical and chemical characters of the species, land type, seasonal and diurnal variations of the meteorological variables; and deposition velocity derived by distributions of the species with height in CL. Variational rules of the concentration and deposition velocity with both height and time are simulated with the model for both corn and forest canopies. Results predicted with the bulk deposition velocity derived in the paper consist well with experimental data.
文摘The magnitude of river morphological changes are better analyzed through the use of quantitative approaches, wherein resolution accuracy and uncertainty assessment are treated as crucial key-factors. In this sense, the creation of precise DEMs （Digital Elevation Models） of rivers represents an affordable tool to analyze geomorphic variations and budgets, except for wetted areas, where reliable channel digitalization can normally be obtained only using expensive bathymetric surveys. The proposed work aims at improving channel surface models without having available bathymetric sensors, by deriving dry areas elevations from LiDAR data and water depth of wetted areas from aerial photos through a predictive depth-colour relationship. The methodology was applied to two different sub-reaches of the Piave River, a gravel-bed river which suffered severe flood events in 2010. Erosion and deposition patterns were identified through DEM differencing, showing a predominance of scour processes which can lead to channel instability situations. The bathymetric output was compared to other previously-derived models confirming the accuracy of the in-channel elevation estimates. Finally, a discussion on the role played by longitudinal protections during the studied flood events is proposed, focusing the attention on the incidence of two major bank erosions that removed significant volumes of stable areas.
