V2O5/NaV6O15 nanocomposites were synthesized by a facile hydrothermal method using VO2(B)nanoarrays as the precursor.X-ray diffraction,scanning electron microscopy and transmission electron microscopy,and galvanostati...V2O5/NaV6O15 nanocomposites were synthesized by a facile hydrothermal method using VO2(B)nanoarrays as the precursor.X-ray diffraction,scanning electron microscopy and transmission electron microscopy,and galvanostatic charge-discharge test were used to evaluate the structures,morphologies and electrochemical performance of samples,respectively.The results show that the nanocomposites are composed of one-dimensional nanobelts,preserving the morphology of the precursor well,and the hydrothermal reaction time has a significant effect on the phase contents and electrochemical performance of the composites.Compared with pure V2O5,V2O5/NaV6O15 nanocomposites exhibit enhanced electrochemical performance as cathode for sodium-ion batteries.It should be ascribed to the synergistic effect between V2O5 with high capacity and NaV6O15 with good cycling performance,and the introduced massive interfacial areas which can provide additional ion storage sites and improve the electronic and ionic conductivities.展开更多
The rechargeable magnesium batteries(RMBs)are getting more and more attention because of their high-energy density,high-security and low-cost.Nevertheless,the high charge density of Mg^2+makes the diffusion of Mg2+in ...The rechargeable magnesium batteries(RMBs)are getting more and more attention because of their high-energy density,high-security and low-cost.Nevertheless,the high charge density of Mg^2+makes the diffusion of Mg2+in the conventional cathodes very slow,resulting in a lack of appropriate electrode materials for RMBs.In this work,we enlarge the layer spacing of V2Os by introducing Na^2+in the crystal structure to promote the diffusion kinetics of Mg^2+.The NaVeO15(NVO)synthesized by a facile method is studied as a cathode material for RMBs with the anhydrous pure Mg^2+electrolyte.As a result,the NVO not only exhibits high discharge capacity(119.2 mAh:g^-1 after 100 cycles at the current density of 20 mA:g^-1)and working voltage(above 1.6 V vs.Mg^2+/Mg),but also expresses good rate capability.Besides,the eX-situ characterizations results reveal that the Mg^2+storage mechanism in NVO is based on the intercalation and deintercalation.The density functional theory(DFT)calculation results further indicate that Mg^2+tends to occupy the semi-occupied sites of Na^+in the NVO.Moreover,the galvanostatic intermittent titration technique(GITT)demonstrates that NVO electrode has the fast diffusion kinetics of Mg^2+during discharge process ranging from 7.55×10^-13 to2.41×10^-11 cm^2·s^-1.Our work proves that the NVO is a potential cathode material for RMBs.展开更多
In this work, we demonstrate an effective method to improve capacitive performance of NaV6O（15） intrinsically by annealing. NaV6O（15） nanorods（NRs） prepared by a simple annealing treatment exhibit significantly ...In this work, we demonstrate an effective method to improve capacitive performance of NaV6O（15） intrinsically by annealing. NaV6O（15） nanorods（NRs） prepared by a simple annealing treatment exhibit significantly improved electrochemical performance compared with the untreated NaV6O（15） electrode, and yield a high specific capacitance（402.8 F/g at 300 mA/g）. Furthermore, the annealing treated nanorods show excellent rate capability and cycling stability（ca. 80% capacitance retention after 1000 cycles at a scan rate of100 mV/s）. Our results have confirmed that the annealing treatment has great influence on the capacitive performance of NaV6O（15）, which may be attributed to the intrinsic three dimensional（3D） tunneled structures of NaV6O（15）, and NR morphology. These findings may further broaden the application of NaV6O（15）-based materials for high performance supercapacitors（SCs）, aqueous rechargeable lithium batteries and Li-ion capacitors.展开更多
基金Project(2020JJ5102)supported by the Natural Science Foundation of Hunan Province,ChinaProject(19A111)supported by the Scientific Research Fund of Hunan Provincial Education Department,China。
文摘V2O5/NaV6O15 nanocomposites were synthesized by a facile hydrothermal method using VO2(B)nanoarrays as the precursor.X-ray diffraction,scanning electron microscopy and transmission electron microscopy,and galvanostatic charge-discharge test were used to evaluate the structures,morphologies and electrochemical performance of samples,respectively.The results show that the nanocomposites are composed of one-dimensional nanobelts,preserving the morphology of the precursor well,and the hydrothermal reaction time has a significant effect on the phase contents and electrochemical performance of the composites.Compared with pure V2O5,V2O5/NaV6O15 nanocomposites exhibit enhanced electrochemical performance as cathode for sodium-ion batteries.It should be ascribed to the synergistic effect between V2O5 with high capacity and NaV6O15 with good cycling performance,and the introduced massive interfacial areas which can provide additional ion storage sites and improve the electronic and ionic conductivities.
基金We gratefully acknowledge the financial support from the National Natural Science Foundation of China(Nos.21875198 and 21621091).
文摘The rechargeable magnesium batteries(RMBs)are getting more and more attention because of their high-energy density,high-security and low-cost.Nevertheless,the high charge density of Mg^2+makes the diffusion of Mg2+in the conventional cathodes very slow,resulting in a lack of appropriate electrode materials for RMBs.In this work,we enlarge the layer spacing of V2Os by introducing Na^2+in the crystal structure to promote the diffusion kinetics of Mg^2+.The NaVeO15(NVO)synthesized by a facile method is studied as a cathode material for RMBs with the anhydrous pure Mg^2+electrolyte.As a result,the NVO not only exhibits high discharge capacity(119.2 mAh:g^-1 after 100 cycles at the current density of 20 mA:g^-1)and working voltage(above 1.6 V vs.Mg^2+/Mg),but also expresses good rate capability.Besides,the eX-situ characterizations results reveal that the Mg^2+storage mechanism in NVO is based on the intercalation and deintercalation.The density functional theory(DFT)calculation results further indicate that Mg^2+tends to occupy the semi-occupied sites of Na^+in the NVO.Moreover,the galvanostatic intermittent titration technique(GITT)demonstrates that NVO electrode has the fast diffusion kinetics of Mg^2+during discharge process ranging from 7.55×10^-13 to2.41×10^-11 cm^2·s^-1.Our work proves that the NVO is a potential cathode material for RMBs.
基金supported by the National Basic Research Program of China (Grant No. 2012CB619302)the Science and Technology Bureau of Wuhan City (No. 2014010101010003)+2 种基金the Key Laboratory of Infrared Imaging Materials and Detectors,Shanghai Institute of Technical Physics,Chinese Academy of Sciences (Grant No. IIMDKFJJ-15-07)the National Natural Science Foundation of China (Grant No. 11574166)the Director Fund of WNLO
文摘In this work, we demonstrate an effective method to improve capacitive performance of NaV6O（15） intrinsically by annealing. NaV6O（15） nanorods（NRs） prepared by a simple annealing treatment exhibit significantly improved electrochemical performance compared with the untreated NaV6O（15） electrode, and yield a high specific capacitance（402.8 F/g at 300 mA/g）. Furthermore, the annealing treated nanorods show excellent rate capability and cycling stability（ca. 80% capacitance retention after 1000 cycles at a scan rate of100 mV/s）. Our results have confirmed that the annealing treatment has great influence on the capacitive performance of NaV6O（15）, which may be attributed to the intrinsic three dimensional（3D） tunneled structures of NaV6O（15）, and NR morphology. These findings may further broaden the application of NaV6O（15）-based materials for high performance supercapacitors（SCs）, aqueous rechargeable lithium batteries and Li-ion capacitors.
