Na_(4)Fe_(3)(PO_(4))_(2)(P_(2)O_(7))(NFPP)is currently drawing increased attention as a sodium-ion batteries(SIBs)cathode due to the cost-effective and NASICON-type structure features.Owing to the sluggish electron an...Na_(4)Fe_(3)(PO_(4))_(2)(P_(2)O_(7))(NFPP)is currently drawing increased attention as a sodium-ion batteries(SIBs)cathode due to the cost-effective and NASICON-type structure features.Owing to the sluggish electron and Na~+conductivities,however,its real implementation is impeded by the grievous capacity decay and inferior rate capability.Herein,multivalent cation substituted microporous Na_(3.9)Fe_(2.9)Al_(0.1)(PO_(4))_(2)(P_(2)O_(7))(NFAPP)with wide operation-temperature is elaborately designed through regulating structure/interface coupled electron/ion transport.Greatly,the derived Na vacancy and charge rearrangement induced by trivalent Al^(3+)substitution lower the ions diffusion barriers,thereby endowing faster electron transport and Na^(+)mobility.More importantly,the existing Al-O-P bonds strengthen the local environment and alleviate the volume vibration during(de)sodiation,enabling highly reversible valence variation and structural evolution.As a result,remarkable cyclability(over 10,000 loops),ultrafast rate capability(200 C),and exceptional all-climate stability(-40-60℃)in half/full cells are demonstrated.Given this,the rational work might provide an actionable strategy to promote the electrochemical property of NFPP,thus unveiling the great application prospect of sodium iron mixed phosphate materials.展开更多
DNA persistence length is a key parameter for quantitative interpretation of the conformational properties of DNA and related to the bending rigidity of DNA.A series of experiments pointed out that,in the DNA condensa...DNA persistence length is a key parameter for quantitative interpretation of the conformational properties of DNA and related to the bending rigidity of DNA.A series of experiments pointed out that,in the DNA condensation process by multivalent cations,the condensed DNA takes elongated coil or compact globule states and the population of the compact globule states increases with an increase in ionic concentration.At the same time,single molecule experiments carried out in solution with multivalent cations(such as spermidine,spermine)indicated that DNA persistence length strongly depends on the ionic concentration.In order to revolve the effects of ionic concentration dependence of persistence length on DNA condensation,a model including the ionic concentration dependence of persistence length and strong correlation of multivalent cation on DNA is provided.The autocorrelation function of the tangent vectors is found as an effective way to detect the ionic concentration dependence of toroidal conformations.With an increase in ion concentration,the first periodic oscillation contained in the autocorrelation function shifts,the number of segment contained in the first periodic oscillation decreases gradually.According to the experiments,the average long-axis length is defined to estimate the ionic concentration dependence of condensation process further.The relation between long-axis length and ionic concentration matches the experimental results qualitatively.展开更多
基金supported by the National Natural Science Foundation of China(52325405,52261135632,and U21A20284)the Science and Technology Foundation of Guizhou Province(QKHZC[2020]2Y037)+1 种基金the Fundamental Research Funds for the Central Universities of Central South University(2023XQLH070,2023XQLH069)the U19 station in the National Synchrotron Radiation Laboratory(NSRL)。
文摘Na_(4)Fe_(3)(PO_(4))_(2)(P_(2)O_(7))(NFPP)is currently drawing increased attention as a sodium-ion batteries(SIBs)cathode due to the cost-effective and NASICON-type structure features.Owing to the sluggish electron and Na~+conductivities,however,its real implementation is impeded by the grievous capacity decay and inferior rate capability.Herein,multivalent cation substituted microporous Na_(3.9)Fe_(2.9)Al_(0.1)(PO_(4))_(2)(P_(2)O_(7))(NFAPP)with wide operation-temperature is elaborately designed through regulating structure/interface coupled electron/ion transport.Greatly,the derived Na vacancy and charge rearrangement induced by trivalent Al^(3+)substitution lower the ions diffusion barriers,thereby endowing faster electron transport and Na^(+)mobility.More importantly,the existing Al-O-P bonds strengthen the local environment and alleviate the volume vibration during(de)sodiation,enabling highly reversible valence variation and structural evolution.As a result,remarkable cyclability(over 10,000 loops),ultrafast rate capability(200 C),and exceptional all-climate stability(-40-60℃)in half/full cells are demonstrated.Given this,the rational work might provide an actionable strategy to promote the electrochemical property of NFPP,thus unveiling the great application prospect of sodium iron mixed phosphate materials.
基金Supported by National Natural Science Foundation of China under Grant Nos.11047022,11204045,11464004 and 31360215The Research Foundation from Ministry of Education of China(212152)+4 种基金Guizhou Provincial Tracking Key Program of Social Development(SY20123089SZ20113069)The General Financial Grant from the China Postdoctoral Science Foundation(2014M562341)The Research Foundation for Young University Teachers from Guizhou University(201311)The West Light Foundation(2015)and College Innovation Talent Team of Guizhou Province,(2014)32
文摘DNA persistence length is a key parameter for quantitative interpretation of the conformational properties of DNA and related to the bending rigidity of DNA.A series of experiments pointed out that,in the DNA condensation process by multivalent cations,the condensed DNA takes elongated coil or compact globule states and the population of the compact globule states increases with an increase in ionic concentration.At the same time,single molecule experiments carried out in solution with multivalent cations(such as spermidine,spermine)indicated that DNA persistence length strongly depends on the ionic concentration.In order to revolve the effects of ionic concentration dependence of persistence length on DNA condensation,a model including the ionic concentration dependence of persistence length and strong correlation of multivalent cation on DNA is provided.The autocorrelation function of the tangent vectors is found as an effective way to detect the ionic concentration dependence of toroidal conformations.With an increase in ion concentration,the first periodic oscillation contained in the autocorrelation function shifts,the number of segment contained in the first periodic oscillation decreases gradually.According to the experiments,the average long-axis length is defined to estimate the ionic concentration dependence of condensation process further.The relation between long-axis length and ionic concentration matches the experimental results qualitatively.
