Zinc metal anodes in aqueous batteries confront critical challenges from dendrite growth and side reactions at the electrode-electrolyte interface,where three phases coexist,including solid zinc metal,liquid electroly...Zinc metal anodes in aqueous batteries confront critical challenges from dendrite growth and side reactions at the electrode-electrolyte interface,where three phases coexist,including solid zinc metal,liquid electrolyte,and gaseous hydrogen bubbles.While hydrogen bubbles are conventionally perceived as detrimental byproducts,this study redefines their dual role through a phase-field model that resolves electrodeposition dynamics with multiphase interactions.Static hydrogen bubbles suppress dendrite formation beneath their shielded zones by blocking ion transport yet accelerate dendrite growth at bubble edges through electric field distortion and localized ion preservation,leading to an over 200 % increase in maximum dendrite length.Larger bubbles and closer proximity to the zinc surface amplify dendrite nucleation and elongation rates.In contrast,moving bubbles homogenize ion flux through hydrodynamic stirring,suppressing edge-localized dendrite growth.Lateral motion is more effective than vertical motion in dendrite suppression,reducing dendrite length by 53 % compared to static bubbles.Notably,oscillating bubbles combining lateral and vertical motion synergize ion blocking and preservation effects,which suppress dendrite growth more effectively,surpassing even bubble-free systems.By correlating bubble dynamics,including size,proximity,and mobility,with dendrite behavior,this work redefines hydrogen bubbles beyond mere byproducts to tunable design elements.Active bubble oscillation engineering strategies,such as ultrasonic agitation,can stabilize zinc electrodeposition by disrupting bubble adhesion and leveraging bubble dynamics.This work bridges multiphase interactions and interfacial deposition dynamics,offering pathways beyond conventional wisdom to mitigate dendrite growth and advance high-performance zinc batteries.展开更多
The thermosolutal convection can alter segregation pattern,change dendrite morphology and even cause freckles formation in alloy solidification.In this work,the multiphase-field model was coupled with lattice Boltzman...The thermosolutal convection can alter segregation pattern,change dendrite morphology and even cause freckles formation in alloy solidification.In this work,the multiphase-field model was coupled with lattice Boltzmann method to simulate the dendrite growth under melt convection in superalloy solidification.In the isothermal solidification simulations,zero and normal gravitational accelerations were applied to investigate the effects of gravity on the dendrite morphology and the magnitude of melt flow.The solute distribution of each alloy component along with the dendrite tip velocity during solidification was obtained,and the natural convection has been confirmed to affect the microsegregation pattern and the dendrite growth velocity.In the directional solidification simulations,two typical temperature gradients were applied,and the dendrite morphology and fluid velocity in the mushy zone during solidification were analyzed.It is found that the freckles will form when the average fluid velocity in the mushy zone exceeds the withdraw velocity.展开更多
Ferroelectric nanostructures are attracting considerable attention due to their unusual physical properties and potential applications in memory devices and nanoelectromechanical systems.It has been found that low-dim...Ferroelectric nanostructures are attracting considerable attention due to their unusual physical properties and potential applications in memory devices and nanoelectromechanical systems.It has been found that low-dimensional ferroelectrics,such as ferroelectric nanodots,ferroelectric nanotubes and ferroelectric thinfilms,exhibit polarization vortices or vortex-like domain structures due to the strong depolarizationfield and the size effect.The polarization vortex is regarded as a new toroidal order in ferroelectrics which is different from the rectilinear order of polarization.The vortex states of polarization are bistable and can be switched from one state to the other,which holds the potential application in next generation ferroelectric memories.This paper brie°y reviews the recent work on the phasefield studies of polarization vortex in ferroelectric nanostructures.The homogeneous bulk thermodynamics of ferroelectrics isfirst introduced based on the LandauDevonshire theory.To describe the inhomogeneous polarization distribution in ferroelectrics,the phasefield model including interface thermodynamics is then presented in the form of time-dependent GinzburgLandau equations.展开更多
基金supported by the grants from the Research Grants Council of the Hong Kong Special Administrative Region, China (Project Nos.C5031-20G)the Guangdong Major Project of Basic and Applied Basic Research (2023B0303000002)the high level of special funds (G03034K001)。
文摘Zinc metal anodes in aqueous batteries confront critical challenges from dendrite growth and side reactions at the electrode-electrolyte interface,where three phases coexist,including solid zinc metal,liquid electrolyte,and gaseous hydrogen bubbles.While hydrogen bubbles are conventionally perceived as detrimental byproducts,this study redefines their dual role through a phase-field model that resolves electrodeposition dynamics with multiphase interactions.Static hydrogen bubbles suppress dendrite formation beneath their shielded zones by blocking ion transport yet accelerate dendrite growth at bubble edges through electric field distortion and localized ion preservation,leading to an over 200 % increase in maximum dendrite length.Larger bubbles and closer proximity to the zinc surface amplify dendrite nucleation and elongation rates.In contrast,moving bubbles homogenize ion flux through hydrodynamic stirring,suppressing edge-localized dendrite growth.Lateral motion is more effective than vertical motion in dendrite suppression,reducing dendrite length by 53 % compared to static bubbles.Notably,oscillating bubbles combining lateral and vertical motion synergize ion blocking and preservation effects,which suppress dendrite growth more effectively,surpassing even bubble-free systems.By correlating bubble dynamics,including size,proximity,and mobility,with dendrite behavior,this work redefines hydrogen bubbles beyond mere byproducts to tunable design elements.Active bubble oscillation engineering strategies,such as ultrasonic agitation,can stabilize zinc electrodeposition by disrupting bubble adhesion and leveraging bubble dynamics.This work bridges multiphase interactions and interfacial deposition dynamics,offering pathways beyond conventional wisdom to mitigate dendrite growth and advance high-performance zinc batteries.
基金financially supported by the National Key Research and Development Program of China(No.2017YFB0701503)the National Science and Technology Major Project(No.2017ZX04014001)the National Natural Science Foundation of China(No.51374137).
文摘The thermosolutal convection can alter segregation pattern,change dendrite morphology and even cause freckles formation in alloy solidification.In this work,the multiphase-field model was coupled with lattice Boltzmann method to simulate the dendrite growth under melt convection in superalloy solidification.In the isothermal solidification simulations,zero and normal gravitational accelerations were applied to investigate the effects of gravity on the dendrite morphology and the magnitude of melt flow.The solute distribution of each alloy component along with the dendrite tip velocity during solidification was obtained,and the natural convection has been confirmed to affect the microsegregation pattern and the dendrite growth velocity.In the directional solidification simulations,two typical temperature gradients were applied,and the dendrite morphology and fluid velocity in the mushy zone during solidification were analyzed.It is found that the freckles will form when the average fluid velocity in the mushy zone exceeds the withdraw velocity.
基金The work was financially supported by the Natural Science Foundation of China under Grants 11002123 and 11090333Key Team of Technological Innovation of Zhejiang Province under Grant 2011R09025-07Zhejiang Provincial Natural Science Foundation under Grant R6110115.TY Zhang thank the Pao Yu Kong foundation for the partial¯nancial support.
文摘Ferroelectric nanostructures are attracting considerable attention due to their unusual physical properties and potential applications in memory devices and nanoelectromechanical systems.It has been found that low-dimensional ferroelectrics,such as ferroelectric nanodots,ferroelectric nanotubes and ferroelectric thinfilms,exhibit polarization vortices or vortex-like domain structures due to the strong depolarizationfield and the size effect.The polarization vortex is regarded as a new toroidal order in ferroelectrics which is different from the rectilinear order of polarization.The vortex states of polarization are bistable and can be switched from one state to the other,which holds the potential application in next generation ferroelectric memories.This paper brie°y reviews the recent work on the phasefield studies of polarization vortex in ferroelectric nanostructures.The homogeneous bulk thermodynamics of ferroelectrics isfirst introduced based on the LandauDevonshire theory.To describe the inhomogeneous polarization distribution in ferroelectrics,the phasefield model including interface thermodynamics is then presented in the form of time-dependent GinzburgLandau equations.
