Due to the unique structure of perovskite materials,their capacitance can be improved by introducing oxygen vacancy.In this paper,the LaMnO3-δ material containing oxygen vacancy was synthesized by molten salt method ...Due to the unique structure of perovskite materials,their capacitance can be improved by introducing oxygen vacancy.In this paper,the LaMnO3-δ material containing oxygen vacancy was synthesized by molten salt method in KNO3-NaNO3-NaNO2 melt.The La-Mn-O crystal grows gradually in molten salt with the increase of temperature.It was confirmed that LaMnO3-δ with perovskite structure and incomplete oxygen content were synthesized by molten salt method and presented a three-dimensional shape.LaMnO3-δ stores energy by redox reaction and adsorption of OH-in electrolyte simultaneously.In comparison with the stoichiometric LaMnO3 prepared by the sol-gel method,LaMnO3-δ prepared by molten salt method proffered higher capacitance and better performance.The galvanostatic charge-discharge curve showed specific capacitance of 973.5 F/g under current density of 1 A/g in 6 M KOH.The capacitance of LaMn03-δ was 82.7%under condition of 5 A/g compared with the capacitance at the current of 1A/g,and the specific capacitances of 648.0 and 310.0 F/g were obtained after 2000 and 5000 cycles of galvanostatic charging-discharging,respectively.Molten salt synthesis method is relatively simple and suitable for industrial scale,presenting a promising prospect in the synthesis of perovskite oxide materials.展开更多
Polyvinyl Pyrrolidone（PVP）/（Lanthanum nitrate and Manganese acetate） composite microfibres were fabricated by electrospinning technique. SEM micrographs indicated that the surface of the composite microfibres was ...Polyvinyl Pyrrolidone（PVP）/（Lanthanum nitrate and Manganese acetate） composite microfibres were fabricated by electrospinning technique. SEM micrographs indicated that the surface of the composite microfibres was smooth, and the diameter of the microfibres was in the range of 1-2μm. XRD analysis revealed that the composite microfibres were amorphous in structure. LaMnO3 ultrafine fibres were fabricated by calcination of the PVP/[La（NO3）3＋Mn（CH3COO）2] composite microfibres, The diameters of LaMnO3 ultrafine fibres were smaller than those of the PVP/[La（NO3）3＋Mn（CH3COO）2] composite microfibres. The surface of the LaMnO3 ultrafine fibres became coarse with the increase of calcination temperatures. LaMnO3 hollow-centered and porous ultrafine fibres formed by nanoparticles were acquired when firing temperature was 600-900℃. SEM analysis indicated that the diameters of the synthesized LaMnO3 ultrafine fibres were in the range of 500-800 nm with the mean wall thickness of 100 nm, and their lengths were greater than 100 ~tm. XRD analysis revealed that the crystal structure of LaMnO3 ultrafine fibres was orthorhombic with space group Pbnm. Possible formation mechanism for LaMnO3 ultrafine fibres was preliminarily proposed.展开更多
基金financially supported by the China Scholarship Council,the National Natural Science Foundation of China(21976047,21790373 and 51774104)the Fundamental Research funds for the Central Universities(3072019CF1005)+1 种基金the Scientific Research and Special Foundation Heilongjiang Postdoctoral Science Foundation(LBH-Q15019,LBH-Q15020 and LBH-TZ0411)Ph.D.Student Research and Innovation Fund of the Fundamental Research Funds for the Central Universities(3072019GIP1011)。
文摘Due to the unique structure of perovskite materials,their capacitance can be improved by introducing oxygen vacancy.In this paper,the LaMnO3-δ material containing oxygen vacancy was synthesized by molten salt method in KNO3-NaNO3-NaNO2 melt.The La-Mn-O crystal grows gradually in molten salt with the increase of temperature.It was confirmed that LaMnO3-δ with perovskite structure and incomplete oxygen content were synthesized by molten salt method and presented a three-dimensional shape.LaMnO3-δ stores energy by redox reaction and adsorption of OH-in electrolyte simultaneously.In comparison with the stoichiometric LaMnO3 prepared by the sol-gel method,LaMnO3-δ prepared by molten salt method proffered higher capacitance and better performance.The galvanostatic charge-discharge curve showed specific capacitance of 973.5 F/g under current density of 1 A/g in 6 M KOH.The capacitance of LaMn03-δ was 82.7%under condition of 5 A/g compared with the capacitance at the current of 1A/g,and the specific capacitances of 648.0 and 310.0 F/g were obtained after 2000 and 5000 cycles of galvanostatic charging-discharging,respectively.Molten salt synthesis method is relatively simple and suitable for industrial scale,presenting a promising prospect in the synthesis of perovskite oxide materials.
文摘Polyvinyl Pyrrolidone（PVP）/（Lanthanum nitrate and Manganese acetate） composite microfibres were fabricated by electrospinning technique. SEM micrographs indicated that the surface of the composite microfibres was smooth, and the diameter of the microfibres was in the range of 1-2μm. XRD analysis revealed that the composite microfibres were amorphous in structure. LaMnO3 ultrafine fibres were fabricated by calcination of the PVP/[La（NO3）3＋Mn（CH3COO）2] composite microfibres, The diameters of LaMnO3 ultrafine fibres were smaller than those of the PVP/[La（NO3）3＋Mn（CH3COO）2] composite microfibres. The surface of the LaMnO3 ultrafine fibres became coarse with the increase of calcination temperatures. LaMnO3 hollow-centered and porous ultrafine fibres formed by nanoparticles were acquired when firing temperature was 600-900℃. SEM analysis indicated that the diameters of the synthesized LaMnO3 ultrafine fibres were in the range of 500-800 nm with the mean wall thickness of 100 nm, and their lengths were greater than 100 ~tm. XRD analysis revealed that the crystal structure of LaMnO3 ultrafine fibres was orthorhombic with space group Pbnm. Possible formation mechanism for LaMnO3 ultrafine fibres was preliminarily proposed.
