Because of its superior safety and excellent processability,solid polymer electrolytes(SPEs)have attracted widespread attention.In lithium based batteries,SPEs have great prospects in replacing leaky and flammable liq...Because of its superior safety and excellent processability,solid polymer electrolytes(SPEs)have attracted widespread attention.In lithium based batteries,SPEs have great prospects in replacing leaky and flammable liquid electrolytes.However,the low ionic conductivity of SPEs cannot meet the requirements of high energy density systems,which is also an important obstacle to its practical application.In this respect,escalating charge carriers(i.e.Li^(+))and Li^(+)transport paths are two major aspects of improving the ionic conductivity of SPEs.This article reviews recent advances from the two perspectives,and the underlying mechanism of these proposed strategies is discussed,including increasing the Li^(+)number and optimizing the Li^(+)transport paths through increasing the types and shortening the distance of Li^(+)transport path.It is hoped that this article can enlighten profound thinking and open up new ways to improve the ionic conductivity of SPEs.展开更多
Natural aquifers usually exhibit complex physical and chemical heterogeneities,which are key factors complicating kinetic processes,such as contaminant transport and transformation,posing a great challenge in the reme...Natural aquifers usually exhibit complex physical and chemical heterogeneities,which are key factors complicating kinetic processes,such as contaminant transport and transformation,posing a great challenge in the remediation of contaminated groundwater.Aquifer heterogeneity usually leads to a distinct feature,the so-called“anomalous transport”in groundwater,which deviates from the phenomenon described by the classical advection-dispersion equation(ADE)based on Fick’s Law.Anomalous transport,also known as non-Fickian dispersion or“anomalous dispersion”in a broad sense,can explain the hydrogeological mechanism that leads to the temporally continuous deterioration of water quality and rapid spatial expansion of pollutant plumes.Contaminants enter and then are retained in the low-permeability matrix from the high-permeability zone via molecular diffusion,chemical adsorption,and other mass exchange effects.This process can be reversed when the concentration of pollutants in high-permeability zones is relatively low.The contaminants slowly return to the high-permeability zones through reverse molecular diffusion,resulting in sub-dispersive anomalous transport leading to the chronic gradual deterioration of water quality.Meanwhile,some contaminants are rapidly transported along the interconnected preferential flow paths,resulting in super-dispersive anomalous transport,which leads to the rapid spread of contaminants.Aquifer heterogeneity is also an important factor that constrains the efficacy of groundwater remediation,while the development,application,and evaluation of groundwater remediation technologies are usually based on the Fickian dispersion process predicted by the ADE equation.Comprehensive studies of the impacts of non-Fickian dispersion on contaminant transport and remediation are still needed.This article reviews the non-Fickian dispersion phenomenon caused by the heterogeneity of geological media,summarizes the processes and current understanding of contaminant migration and transformation in hi展开更多
A binary continuum model for dendritic solidification transport phenomena and corresponding numerical algorithm for the strong nonlinear coupling of T-fS-CL were extended to multicomponent alloys solidified under cond...A binary continuum model for dendritic solidification transport phenomena and corresponding numerical algorithm for the strong nonlinear coupling of T-fS-CL were extended to multicomponent alloys solidified under condition of Biot≤0.1. Based on the extended model/algorithm, a method considering heat transfer was proposed to predict the solidification paths and microsegregation of alloys solidified under the same condition. The new algorithm and method were closely coupled with the commercial Thermo-Calc package via its TQ6-interface codes for instantaneous determination of the related thermodynamic data at each calculation time step. The sample simulation performed on an Al-2Si-3Mg alloy system indicates the availability and reliability of the model/algorithm and the proposed method for predicting solidification paths and microsegregation. Computional and experimental investigations on an Al-5.17Cu-2.63Si ternary alloy were conducted, and a reasonable agreement between the computation and experiment was obtained.展开更多
基金supported by the National Natural Science Foundation of China(51872196)the Natural Science Foundation of Tianjin,China(17JCJQJC44100)the National Postdoctoral Program for Innovative Talents,China(BX20190232)。
文摘Because of its superior safety and excellent processability,solid polymer electrolytes(SPEs)have attracted widespread attention.In lithium based batteries,SPEs have great prospects in replacing leaky and flammable liquid electrolytes.However,the low ionic conductivity of SPEs cannot meet the requirements of high energy density systems,which is also an important obstacle to its practical application.In this respect,escalating charge carriers(i.e.Li^(+))and Li^(+)transport paths are two major aspects of improving the ionic conductivity of SPEs.This article reviews recent advances from the two perspectives,and the underlying mechanism of these proposed strategies is discussed,including increasing the Li^(+)number and optimizing the Li^(+)transport paths through increasing the types and shortening the distance of Li^(+)transport path.It is hoped that this article can enlighten profound thinking and open up new ways to improve the ionic conductivity of SPEs.
基金supported by the National Key R&D Program of China(Grant No.2016YFC0402806)the National Natural Science Foundation of China(Grant Nos.41931292,42007162&41722208)the Natural Science Foundation of Guangdong Province(CN)(Grant No.2020A1515010891).
文摘Natural aquifers usually exhibit complex physical and chemical heterogeneities,which are key factors complicating kinetic processes,such as contaminant transport and transformation,posing a great challenge in the remediation of contaminated groundwater.Aquifer heterogeneity usually leads to a distinct feature,the so-called“anomalous transport”in groundwater,which deviates from the phenomenon described by the classical advection-dispersion equation(ADE)based on Fick’s Law.Anomalous transport,also known as non-Fickian dispersion or“anomalous dispersion”in a broad sense,can explain the hydrogeological mechanism that leads to the temporally continuous deterioration of water quality and rapid spatial expansion of pollutant plumes.Contaminants enter and then are retained in the low-permeability matrix from the high-permeability zone via molecular diffusion,chemical adsorption,and other mass exchange effects.This process can be reversed when the concentration of pollutants in high-permeability zones is relatively low.The contaminants slowly return to the high-permeability zones through reverse molecular diffusion,resulting in sub-dispersive anomalous transport leading to the chronic gradual deterioration of water quality.Meanwhile,some contaminants are rapidly transported along the interconnected preferential flow paths,resulting in super-dispersive anomalous transport,which leads to the rapid spread of contaminants.Aquifer heterogeneity is also an important factor that constrains the efficacy of groundwater remediation,while the development,application,and evaluation of groundwater remediation technologies are usually based on the Fickian dispersion process predicted by the ADE equation.Comprehensive studies of the impacts of non-Fickian dispersion on contaminant transport and remediation are still needed.This article reviews the non-Fickian dispersion phenomenon caused by the heterogeneity of geological media,summarizes the processes and current understanding of contaminant migration and transformation in hi
基金Projects (2008112042) supported by the Open Project of State Key Laboratory of Powder Metallurgy of Central South University, ChinaProjects (50771041, 50801019) supported by the National Natural Science Foundation of ChinaProject (2011CB610406) supported by the National Basic Research Program of China
文摘A binary continuum model for dendritic solidification transport phenomena and corresponding numerical algorithm for the strong nonlinear coupling of T-fS-CL were extended to multicomponent alloys solidified under condition of Biot≤0.1. Based on the extended model/algorithm, a method considering heat transfer was proposed to predict the solidification paths and microsegregation of alloys solidified under the same condition. The new algorithm and method were closely coupled with the commercial Thermo-Calc package via its TQ6-interface codes for instantaneous determination of the related thermodynamic data at each calculation time step. The sample simulation performed on an Al-2Si-3Mg alloy system indicates the availability and reliability of the model/algorithm and the proposed method for predicting solidification paths and microsegregation. Computional and experimental investigations on an Al-5.17Cu-2.63Si ternary alloy were conducted, and a reasonable agreement between the computation and experiment was obtained.
