Lithium metal batteries are promising devices for the next-generation energy storage due to their ultrahigh theoretical specific capacity and extremely low electrochemical potential.Their inherent problem is the forma...Lithium metal batteries are promising devices for the next-generation energy storage due to their ultrahigh theoretical specific capacity and extremely low electrochemical potential.Their inherent problem is the formation of lithium dendrites in cycling,which has induced safety concerns for almost half a century.After understanding the formation mechanism of branching structures,we propose to suppress lithium dendrites by adopting external magnetic fields to induce diffusion enhancement at the interface of the anode,thus attenuating concentration gradient there and reducing the driving force for the formation of dendritic structures.The diffusion coefficient of lithium ions is dependent on the strength of magnetic fields,confirming the effectiveness of magnetic fields in improving Li^(+) diffusion.After employing the magnetic field of0.8 T,the concentration gradients at the growth front becomes nearly half of the control case,which leads to a dendrite-free lithium deposition up to the high current density of 10 mA cm^(-2).Both the Cu|LiCoO_(2) batteries and the symmetric Li | Li coin cells show a long-term stable cycling at high current densities under the assistance of magnetic field.This diffusion enhanced technique promises a facile and general approach to suppress dendritic structures in secondary batteries,which may help to develop quick charging strategies.展开更多
Nucleation widely exists in nature,from cloud formation to haze generation.The classical nucleation theory(CNT)was created to describe the nucleation process,but it fails to predict many experimental phenomena due to ...Nucleation widely exists in nature,from cloud formation to haze generation.The classical nucleation theory(CNT)was created to describe the nucleation process,but it fails to predict many experimental phenomena due to the short consideration of nanoscale phenomena and macroscale dynamics.Although the attachment and detachment of monomers are considered in the developed model of nucleation,the diffusion of chemicals in the bulk is not valued as supersaturation in the nucleation process so far.Here we employ simulation and experimental approaches to investigate how the diffusion of ions affects the nucleation of calcium carbonate.The diffusion of ions is regulated by the viscosity of solvents and the sonication imposed on the solution.It is found that the nucleation rates increased exponentially with the diffusion coefficient of ions,which is beyond the prediction of CNT.This abnormal finding might be ascribed to the involvement of cluster aggregation in the nucleation of calcium carbonate.This study highlights the significance of chemical diffusion in the nucleation process,which may help to revise the nucleation theory and develop solutions for the rational synthesis of materials,as well as for the control of air pollution.展开更多
Rational synthesis of materials is a long-term challenging issue due to the poor understanding on the formation mechanism of material structure and the limited capability in controlling nanoscale crystallization.The e...Rational synthesis of materials is a long-term challenging issue due to the poor understanding on the formation mechanism of material structure and the limited capability in controlling nanoscale crystallization.The emergent in situ electron microscope provides an insight to this issue.By employing an in situ scanning electron microscope,silver crystallization is investigated in real time,in which a reversible crystallization is observed.To disclose this reversible crystallization,the radicals generated by the irradiation of electron beam are calculated.It is found that the concentrations of radicals are spatiotemporally variable in the liquid cell due to the diffusion and reaction of radicals.The fluctuation of the reductive hydrated electrons and the oxidative hydroxyl radicals in the cell leads to the alternative dominance of the reduction and oxidation reactions.The reduction leads to the growth of silver crystals while the oxidation leads to their dissolution,which results in the reversible silver crystallization.A regulation of radical distribution by electron dose rates leads to the formation of diverse silver structures,confirming the dominant role of local chemical concentration in the structure evolution of materials.展开更多
基金financial support from National Natural Science Foundation of China (91934302, 21978298, U1862117)the Innovation Academy for Green Manufacture, Chinese Academy of Sciences (IAGM-2019-A13) is warmly appreciatedsupported by the project from the State Key Laboratory of Multiphase Complex Systems (MPCS-2019-D-12)。
文摘Lithium metal batteries are promising devices for the next-generation energy storage due to their ultrahigh theoretical specific capacity and extremely low electrochemical potential.Their inherent problem is the formation of lithium dendrites in cycling,which has induced safety concerns for almost half a century.After understanding the formation mechanism of branching structures,we propose to suppress lithium dendrites by adopting external magnetic fields to induce diffusion enhancement at the interface of the anode,thus attenuating concentration gradient there and reducing the driving force for the formation of dendritic structures.The diffusion coefficient of lithium ions is dependent on the strength of magnetic fields,confirming the effectiveness of magnetic fields in improving Li^(+) diffusion.After employing the magnetic field of0.8 T,the concentration gradients at the growth front becomes nearly half of the control case,which leads to a dendrite-free lithium deposition up to the high current density of 10 mA cm^(-2).Both the Cu|LiCoO_(2) batteries and the symmetric Li | Li coin cells show a long-term stable cycling at high current densities under the assistance of magnetic field.This diffusion enhanced technique promises a facile and general approach to suppress dendritic structures in secondary batteries,which may help to develop quick charging strategies.
基金financial support from National Natural Science Foundation of China(91934302,21978298,U1862117)the Innovation Academy for Green Manufacture,Chinese Academy of Sciences(IAGM-2019-A13)+1 种基金supported by the project from the State Key Laboratory of Multiphase Complex Systems(MPCS-2017-A-01)the MPCS Facility Upgradation Program。
文摘Nucleation widely exists in nature,from cloud formation to haze generation.The classical nucleation theory(CNT)was created to describe the nucleation process,but it fails to predict many experimental phenomena due to the short consideration of nanoscale phenomena and macroscale dynamics.Although the attachment and detachment of monomers are considered in the developed model of nucleation,the diffusion of chemicals in the bulk is not valued as supersaturation in the nucleation process so far.Here we employ simulation and experimental approaches to investigate how the diffusion of ions affects the nucleation of calcium carbonate.The diffusion of ions is regulated by the viscosity of solvents and the sonication imposed on the solution.It is found that the nucleation rates increased exponentially with the diffusion coefficient of ions,which is beyond the prediction of CNT.This abnormal finding might be ascribed to the involvement of cluster aggregation in the nucleation of calcium carbonate.This study highlights the significance of chemical diffusion in the nucleation process,which may help to revise the nucleation theory and develop solutions for the rational synthesis of materials,as well as for the control of air pollution.
基金The financial support from the National Natural Science Foundation of China(91934302,21978298,U1862117,and 91534123)is warmly appreciatedThis study was supported by the project from the State Key Laboratory of Multiphase Complex Systems(MPCS-2017-A-01)the MPCS Facility Upgradation Program.We appreciate the suggestion by Dr.Juanxiu Xiao from Hainan University.
文摘Rational synthesis of materials is a long-term challenging issue due to the poor understanding on the formation mechanism of material structure and the limited capability in controlling nanoscale crystallization.The emergent in situ electron microscope provides an insight to this issue.By employing an in situ scanning electron microscope,silver crystallization is investigated in real time,in which a reversible crystallization is observed.To disclose this reversible crystallization,the radicals generated by the irradiation of electron beam are calculated.It is found that the concentrations of radicals are spatiotemporally variable in the liquid cell due to the diffusion and reaction of radicals.The fluctuation of the reductive hydrated electrons and the oxidative hydroxyl radicals in the cell leads to the alternative dominance of the reduction and oxidation reactions.The reduction leads to the growth of silver crystals while the oxidation leads to their dissolution,which results in the reversible silver crystallization.A regulation of radical distribution by electron dose rates leads to the formation of diverse silver structures,confirming the dominant role of local chemical concentration in the structure evolution of materials.
