Li3VO4 shows great potential as an intercalation/de-intercalation type anode material for energy-storage devices. Morphology tailoring and surface modification are effective to enhance its lithium storage performance....Li3VO4 shows great potential as an intercalation/de-intercalation type anode material for energy-storage devices. Morphology tailoring and surface modification are effective to enhance its lithium storage performance. In this work, we fabricate carbon coated Li3VO4(C@LVO) rods by a facile morphology inheritance route. The as-prepared C@LVO rods are 400–800 nm in length and 200–400 nm in diameter,and orthorhombic phase with V5+. The unique core-shell rods structure greatly improves the transport ability of electrons and Li+. Such C@LVO submicron-rods as anode materials exhibit excellent rate capability(a reversible capability of 460,438, 416, 359 and 310 m A h g^-1 at 0.2, 1, 2, 5 and 10 C, respectively) and a high stable capacity of 440 and 313 m A h g^-1 up to 300 cycles at 0.2 and 5 C, respectively.展开更多
The anionic redox chemistry(O^2-→O^-)in P2-type sodium-ion battery cathodes has attracted much attention.However,determining how to tune the anionic redox reaction is still a major challenge.Herein,we tune the activi...The anionic redox chemistry(O^2-→O^-)in P2-type sodium-ion battery cathodes has attracted much attention.However,determining how to tune the anionic redox reaction is still a major challenge.Herein,we tune the activity and reversibility of both the anionic and cationic redox reactions of Na0.67Mn0.5Fe0.5O2 though an integrated strategy that combines the advantages of Li2SiO3 coating,Li doping and Si doping,and the initial capacity,rate performance and cycling stability are significantly improved.The in-depth modulation mechanism is revealed by means of neutron diffraction,X-ray absorption spectroscopy,in situ X-ray diffraction,electron paramagnetic resonance spectroscopy,first-principles calculations and so on.The Li2SiO3 coating alleviates the side reactions and enhances the cycling stability.Si^4+doping lowers the Na^+diffusion barrier due to the expanded interlayer spacing.Additionally,Si^4+doping improves the structural stability,oxygen redox activity and reversibility.Li^+doping in Na sites further increases the structure stability.The electron density maps confirm the greater activity of Na and O in the modified sample.Nuclear density maps and bond-valence energy landscapes identify the Na^+migration pathway from Nae site to Naf site(the positions of the Na ions in the crystal structure).The proposed insights into the modulation mechanism of the anionic and cationic redox chemistry are also instructive for designing other oxide-based cathode materials.展开更多
基金supported by the National Natural Science Foundation of China(21476019 and 21676017)
文摘Li3VO4 shows great potential as an intercalation/de-intercalation type anode material for energy-storage devices. Morphology tailoring and surface modification are effective to enhance its lithium storage performance. In this work, we fabricate carbon coated Li3VO4(C@LVO) rods by a facile morphology inheritance route. The as-prepared C@LVO rods are 400–800 nm in length and 200–400 nm in diameter,and orthorhombic phase with V5+. The unique core-shell rods structure greatly improves the transport ability of electrons and Li+. Such C@LVO submicron-rods as anode materials exhibit excellent rate capability(a reversible capability of 460,438, 416, 359 and 310 m A h g^-1 at 0.2, 1, 2, 5 and 10 C, respectively) and a high stable capacity of 440 and 313 m A h g^-1 up to 300 cycles at 0.2 and 5 C, respectively.
基金supported by the National Natural Science Foundation of China(11975238 and 11575192)the Scientific Instrument Developing Project(ZDKYYQ20170001)+3 种基金the International Partnership Program(211211KYSB20170060 and 211211KYSB20180020)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB28000000)the Natural Science Foundation of Beijing Municipality(2182082)The support from University of Chinese Academy of Sciences is also appreciated。
文摘The anionic redox chemistry(O^2-→O^-)in P2-type sodium-ion battery cathodes has attracted much attention.However,determining how to tune the anionic redox reaction is still a major challenge.Herein,we tune the activity and reversibility of both the anionic and cationic redox reactions of Na0.67Mn0.5Fe0.5O2 though an integrated strategy that combines the advantages of Li2SiO3 coating,Li doping and Si doping,and the initial capacity,rate performance and cycling stability are significantly improved.The in-depth modulation mechanism is revealed by means of neutron diffraction,X-ray absorption spectroscopy,in situ X-ray diffraction,electron paramagnetic resonance spectroscopy,first-principles calculations and so on.The Li2SiO3 coating alleviates the side reactions and enhances the cycling stability.Si^4+doping lowers the Na^+diffusion barrier due to the expanded interlayer spacing.Additionally,Si^4+doping improves the structural stability,oxygen redox activity and reversibility.Li^+doping in Na sites further increases the structure stability.The electron density maps confirm the greater activity of Na and O in the modified sample.Nuclear density maps and bond-valence energy landscapes identify the Na^+migration pathway from Nae site to Naf site(the positions of the Na ions in the crystal structure).The proposed insights into the modulation mechanism of the anionic and cationic redox chemistry are also instructive for designing other oxide-based cathode materials.
