Al/conductive coating/α-Pb O2-Ce O2-Ti O2/β-PbO 2-MnO 2-WC-Zr O2 composite electrode material was prepared on Al/conductive coating/α-PbO 2-Ce O2-Ti O2 substrate by electrochemical oxidation co-deposition technique...Al/conductive coating/α-Pb O2-Ce O2-Ti O2/β-PbO 2-MnO 2-WC-Zr O2 composite electrode material was prepared on Al/conductive coating/α-PbO 2-Ce O2-Ti O2 substrate by electrochemical oxidation co-deposition technique. The effects of current density on the chemical composition, electrocatalytic activity, and stability of the composite anode material were investigated by energy dispersive X-ray spectroscopy（EDXS）, anode polarization curves, quasi-stationary polarization（Tafel） curves, electrochemical impedance spectroscopy（EIS）, scanning electron microscopy（SEM）, and X-ray diffraction（XRD）. Results reveal that the composite electrode obtained at 1 A/dm2 possesses the lowest overpotential（0.610 V at 500 A/m2） for oxygen evolution, the best electrocatalytic activity, the longest service life（360 h at 40 °C in 150 g/L H2SO4 solution under 2 A/cm2）, and the lowest cell voltage（2.75 V at 500 A/m2）. Furthermore, with increasing current density, the coating exhibits grain growth and the decrease of content of Mn O2. Only a slight effect on crystalline structure is observed.展开更多
The hydrothermal synthesis of single-crystallineβ-MnO2 nanorods and their chemical conversion into single-crystalline LiMn2O4 nanorods by a simple solid-state reaction were reported.This method has the advantages of ...The hydrothermal synthesis of single-crystallineβ-MnO2 nanorods and their chemical conversion into single-crystalline LiMn2O4 nanorods by a simple solid-state reaction were reported.This method has the advantages of producing pure,single-phase and crystalline nanorods.The LiMn2O4 nanorods have an diameter of about 300 nm.The discharge capacity and cyclic performance of the batteries were investigated.The LiMn2O4 nanorods show better cyclic performance with a capacity retention ratio of 86.2% after 100 cycles.Battery cyclic studies reveal that the prepared LiMn2O4 nanorods have high capacity with a first discharge capacity of 128.7 mA·h/g.展开更多
以MnSO_4·H_2O与NaClO_3为原料,NH_4F为辅助剂,通过水热法合成了海胆状β-MnO_2前驱体,研究了NH_4F用量对前驱体形貌的影响。以形貌最优的β-MnO_2作为前驱体与LiOH·H_2O通过高温烧结合成棒状尖晶石型LiMn_2O_4,并将它与商业M...以MnSO_4·H_2O与NaClO_3为原料,NH_4F为辅助剂,通过水热法合成了海胆状β-MnO_2前驱体,研究了NH_4F用量对前驱体形貌的影响。以形貌最优的β-MnO_2作为前驱体与LiOH·H_2O通过高温烧结合成棒状尖晶石型LiMn_2O_4,并将它与商业MnO_2为前驱体合成的尖晶石型LiMn_2O_4进行了结构和性能比较。通过X射线衍射分析(XRD)、扫描电镜(SEM)以及电化学性能测试等手段对MnO_2前驱体以及尖晶石型LiMn_2O_4产物进行了表征。实验结果表明,棒状LiMn_2O_4具有更优越的电化学性能:0.2C下首次放电比容量为119.8 m Ah/g,最高达到123.2 m Ah/g,30圈循环后,容量保持率为94.07%。展开更多
Nanofibrous pyrolusite （β-MnO2） was synthesized. The particle shape changes from nanofibers to nanoparticles after grinding, and the phase structure does not change. The local environment around the central mangane...Nanofibrous pyrolusite （β-MnO2） was synthesized. The particle shape changes from nanofibers to nanoparticles after grinding, and the phase structure does not change. The local environment around the central manganese ion has a slight change in nanoparticles related to nanofibers. Fourier transform infrared （FTIR） spectra showed that A2u mode frequency shifts from 514 cm-1 to 574 cm-1 to 617 cm-1 gradually while the particle shape and size change from long nanofibers to short fibers and to nanoparticles. The extra vibrational band that is unpredicted by factor group analysis originates from the contribution of A2u mode of the particles with different sizes and shapes in the studied sample. On the basis of Rietveld refinement analysis of XRD profiles and the FTIR spectra, we think that two kinds of MnO6 octahedral geometries, i.e., 4 long＋2 short and 4 short＋2 long, could exist in pyrolusites synthesized by different route. The maximum vibrational frequency in the FTIR spectra of pyrolusites is sensitive to these micro-structures. Assignment of four vibrational bands in the middle and far infrared region has been made.展开更多
基金Projects(51004056,51004057)supported by the National Natural Science Foundation of ChinaProject(KKZ6201152009)supported by the Opening Foundation of Key Laboratory of Inorganic Coating Materials,Chinese Academy of Sciences+2 种基金Project(2010ZC052)supported by the Applied Basic Research Foundation of Yunnan Province,ChinaProject(20125314110011)supported by the Specialized Research Fund for the Doctoral Program of Higher Education,ChinaProject(2010247)supported by Analysis&Testing Foundation of Kunming University of Science and Technology,China
文摘Al/conductive coating/α-Pb O2-Ce O2-Ti O2/β-PbO 2-MnO 2-WC-Zr O2 composite electrode material was prepared on Al/conductive coating/α-PbO 2-Ce O2-Ti O2 substrate by electrochemical oxidation co-deposition technique. The effects of current density on the chemical composition, electrocatalytic activity, and stability of the composite anode material were investigated by energy dispersive X-ray spectroscopy（EDXS）, anode polarization curves, quasi-stationary polarization（Tafel） curves, electrochemical impedance spectroscopy（EIS）, scanning electron microscopy（SEM）, and X-ray diffraction（XRD）. Results reveal that the composite electrode obtained at 1 A/dm2 possesses the lowest overpotential（0.610 V at 500 A/m2） for oxygen evolution, the best electrocatalytic activity, the longest service life（360 h at 40 °C in 150 g/L H2SO4 solution under 2 A/cm2）, and the lowest cell voltage（2.75 V at 500 A/m2）. Furthermore, with increasing current density, the coating exhibits grain growth and the decrease of content of Mn O2. Only a slight effect on crystalline structure is observed.
基金Project(2008AA031205)supported by the National High-tech Research and Development Program of China
文摘The hydrothermal synthesis of single-crystallineβ-MnO2 nanorods and their chemical conversion into single-crystalline LiMn2O4 nanorods by a simple solid-state reaction were reported.This method has the advantages of producing pure,single-phase and crystalline nanorods.The LiMn2O4 nanorods have an diameter of about 300 nm.The discharge capacity and cyclic performance of the batteries were investigated.The LiMn2O4 nanorods show better cyclic performance with a capacity retention ratio of 86.2% after 100 cycles.Battery cyclic studies reveal that the prepared LiMn2O4 nanorods have high capacity with a first discharge capacity of 128.7 mA·h/g.
文摘以MnSO_4·H_2O与NaClO_3为原料,NH_4F为辅助剂,通过水热法合成了海胆状β-MnO_2前驱体,研究了NH_4F用量对前驱体形貌的影响。以形貌最优的β-MnO_2作为前驱体与LiOH·H_2O通过高温烧结合成棒状尖晶石型LiMn_2O_4,并将它与商业MnO_2为前驱体合成的尖晶石型LiMn_2O_4进行了结构和性能比较。通过X射线衍射分析(XRD)、扫描电镜(SEM)以及电化学性能测试等手段对MnO_2前驱体以及尖晶石型LiMn_2O_4产物进行了表征。实验结果表明,棒状LiMn_2O_4具有更优越的电化学性能:0.2C下首次放电比容量为119.8 m Ah/g,最高达到123.2 m Ah/g,30圈循环后,容量保持率为94.07%。
文摘Nanofibrous pyrolusite （β-MnO2） was synthesized. The particle shape changes from nanofibers to nanoparticles after grinding, and the phase structure does not change. The local environment around the central manganese ion has a slight change in nanoparticles related to nanofibers. Fourier transform infrared （FTIR） spectra showed that A2u mode frequency shifts from 514 cm-1 to 574 cm-1 to 617 cm-1 gradually while the particle shape and size change from long nanofibers to short fibers and to nanoparticles. The extra vibrational band that is unpredicted by factor group analysis originates from the contribution of A2u mode of the particles with different sizes and shapes in the studied sample. On the basis of Rietveld refinement analysis of XRD profiles and the FTIR spectra, we think that two kinds of MnO6 octahedral geometries, i.e., 4 long＋2 short and 4 short＋2 long, could exist in pyrolusites synthesized by different route. The maximum vibrational frequency in the FTIR spectra of pyrolusites is sensitive to these micro-structures. Assignment of four vibrational bands in the middle and far infrared region has been made.
