Na-ion diffusion kinetics is a key factor that decided the charge/discharge rate of the electrode materials in Na-ion batteries.In this work,two extreme concentrations of NaMnO_(2) and Na_(2/3)Li_(1/6)Mn_(5/6)O_(2) ar...Na-ion diffusion kinetics is a key factor that decided the charge/discharge rate of the electrode materials in Na-ion batteries.In this work,two extreme concentrations of NaMnO_(2) and Na_(2/3)Li_(1/6)Mn_(5/6)O_(2) are considered,namely,the vacancy migration of Na ions in the fully intercalated and the migration of Na ions in the fully de-intercalated.The Na-vacancy and Na^(+)distribution in NaMnO_(2) migrated along oxygen dumbbell hop(ODH)and tetrahedral site hop(TSH),and the migration energy barriers were 0.374 and 0.296 eV,respectively.In NaLi_(1/6)Mn_(5/6)O_(2),the inhomogeneity of Li doping leads to the narrowing of the interlayer spacing by 0.9%and the increase of the energy barrier by 53.8%.On the other hand,due to the alleviation of Jahn-Teller effect of neighboring Mn,the bonding strength of Mn-O was enhanced,so that the energy barrier of path 2-3 in Mn-L1 and Mn-L2 was the lowest,which was 0.234 and 0.424 eV,respectively.In Na_(1/6)Li_(1/6)Mn_(5/6)O_(2),the migration energy barriers of Na-L2 and Na-L3 are 1.233 and 0.779 eV,respectively,because Li+migrates from the transition(TM)layer to the alkali metal(AM)layer with Na^(+)migration,which requires additional energy.展开更多
The Jahn-Teller distortion plays an important role in determining the exchange interaction in rare-earth manganites.In this work we study the influence of the Jahn-Teller distortion on the magnetic structures of TbMn1...The Jahn-Teller distortion plays an important role in determining the exchange interaction in rare-earth manganites.In this work we study the influence of the Jahn-Teller distortion on the magnetic structures of TbMn1-xFexO3（x = 0,0.02,0.05,0.10,and 0.20） single crystals in the basal MnO2 plane.The decrease in the quadruple splitting with the increasing Fe doping indicates the reduction of the Jahn-Teller distortion,which makes the nearest neighboring（NN） FM interaction dominant over the next nearest neighbor（NNN） AFM interaction.This alteration is favorable for the development of A-type AFM ordering instead of the spiral magnetic ordering,which collapses when x ≥ 0.05.The analysis of dielectric data indicates that the ferroelectricity is arising from the peculiar spiral magnetic ordering.展开更多
Rechargeable aqueous zinc ion batteries(AZIBs)based on manganese dioxide(MnO_(2))have received much attention for large-scale energy storage applications,however,their energy density is mainly limited by the one-elect...Rechargeable aqueous zinc ion batteries(AZIBs)based on manganese dioxide(MnO_(2))have received much attention for large-scale energy storage applications,however,their energy density is mainly limited by the one-electron reaction of Mn4+/Mn3+redox.Herein,Mo dopedδ-MnO_(2)(Mo-MnO_(2))is prepared and used as a high-performance cathode for AZIBs,which delivers an⇌⇌ultrahigh specific capacity of 652 mAh·g^(−1)at 0.2 A·g^(−1)based on the two-step two-electron redox reaction of Mn^(4+)Mn^(3+)Mn^(2+).Ex-situ structural analysis and density functional theory calculation reveal that the Mo^(5+)dopant plays an important role in enhancing the electronic conductivity of Mo-MnO_(2)and promoting Jahn–Teller distortion of octahedral[MnO_(6)]in ZnMn_(2)O_(4),which facilitates the second step redox reaction of Mn^(3+)/Mn_(2+).This work provides a novel cathode materials design with multi-electron redox chemistry to achieve high energy density in AZIBs.展开更多
基金Projects(51602352,51974373,51874358,51772333,61533020) supported by the National Natural Science Foundation of ChinaProject(2019JZZY020123) supported by the Major Scientific and Technological Innovation Projects of Shandong Province,China。
文摘Na-ion diffusion kinetics is a key factor that decided the charge/discharge rate of the electrode materials in Na-ion batteries.In this work,two extreme concentrations of NaMnO_(2) and Na_(2/3)Li_(1/6)Mn_(5/6)O_(2) are considered,namely,the vacancy migration of Na ions in the fully intercalated and the migration of Na ions in the fully de-intercalated.The Na-vacancy and Na^(+)distribution in NaMnO_(2) migrated along oxygen dumbbell hop(ODH)and tetrahedral site hop(TSH),and the migration energy barriers were 0.374 and 0.296 eV,respectively.In NaLi_(1/6)Mn_(5/6)O_(2),the inhomogeneity of Li doping leads to the narrowing of the interlayer spacing by 0.9%and the increase of the energy barrier by 53.8%.On the other hand,due to the alleviation of Jahn-Teller effect of neighboring Mn,the bonding strength of Mn-O was enhanced,so that the energy barrier of path 2-3 in Mn-L1 and Mn-L2 was the lowest,which was 0.234 and 0.424 eV,respectively.In Na_(1/6)Li_(1/6)Mn_(5/6)O_(2),the migration energy barriers of Na-L2 and Na-L3 are 1.233 and 0.779 eV,respectively,because Li+migrates from the transition(TM)layer to the alkali metal(AM)layer with Na^(+)migration,which requires additional energy.
基金Project supported by the National Basic Research Program of China (Grant Nos. 2010CB934202 and 2011CB921801)the National Natural Science Foundation of China (Grant Nos. 11174351,50931006,51021061,and 11034004)
文摘The Jahn-Teller distortion plays an important role in determining the exchange interaction in rare-earth manganites.In this work we study the influence of the Jahn-Teller distortion on the magnetic structures of TbMn1-xFexO3（x = 0,0.02,0.05,0.10,and 0.20） single crystals in the basal MnO2 plane.The decrease in the quadruple splitting with the increasing Fe doping indicates the reduction of the Jahn-Teller distortion,which makes the nearest neighboring（NN） FM interaction dominant over the next nearest neighbor（NNN） AFM interaction.This alteration is favorable for the development of A-type AFM ordering instead of the spiral magnetic ordering,which collapses when x ≥ 0.05.The analysis of dielectric data indicates that the ferroelectricity is arising from the peculiar spiral magnetic ordering.
基金supported by the National Natural Science Foundation of China(Nos.21935001 and 22101015)the National Key Research and Development Program of China(No.2018YFA0702002)the Program for Changjiang Scholars and Innovation Research Team in the University(No.IRT1205).
文摘Rechargeable aqueous zinc ion batteries(AZIBs)based on manganese dioxide(MnO_(2))have received much attention for large-scale energy storage applications,however,their energy density is mainly limited by the one-electron reaction of Mn4+/Mn3+redox.Herein,Mo dopedδ-MnO_(2)(Mo-MnO_(2))is prepared and used as a high-performance cathode for AZIBs,which delivers an⇌⇌ultrahigh specific capacity of 652 mAh·g^(−1)at 0.2 A·g^(−1)based on the two-step two-electron redox reaction of Mn^(4+)Mn^(3+)Mn^(2+).Ex-situ structural analysis and density functional theory calculation reveal that the Mo^(5+)dopant plays an important role in enhancing the electronic conductivity of Mo-MnO_(2)and promoting Jahn–Teller distortion of octahedral[MnO_(6)]in ZnMn_(2)O_(4),which facilitates the second step redox reaction of Mn^(3+)/Mn_(2+).This work provides a novel cathode materials design with multi-electron redox chemistry to achieve high energy density in AZIBs.
