The layered LiNi0.6Co0.2Mn0.2-yMgyO2-zFz（0≤y≤0.12, 0≤z≤0.08） cathode materials were synthesized by combining co-precipitation method and high temperature solid-state reaction, with the help of the ball milling, ...The layered LiNi0.6Co0.2Mn0.2-yMgyO2-zFz（0≤y≤0.12, 0≤z≤0.08） cathode materials were synthesized by combining co-precipitation method and high temperature solid-state reaction, with the help of the ball milling, to investigate the effects of F-Mg doping on LiNi0.6Co0.2Mn0.2O）2. Compared with previous studies, this doping treatment provides substantially improved electrochemical performance in terms of initial coulombic efficiency and cycle performance. The LiNi0.6Co0.2Mn0.11Mg0.09O1.96F0.04 electrode delivers an high capacity retention of 98.6% during the first cycle and a discharge capacity of 189.7 m A·h/g（2.8-4.4 V at 0.2 C）, with the capacity retention of 96.3% after 100 cycles. And electrochemical impedance spectroscopy（EIS） results show that Mg-F co-doping decreases the charge-transfer resistance and enhances the reaction kinetics, which is considered to be the major factor for higher rate performance. It is demonstrated that LiNi0.6Co0.2Mn0.11Mg0.09O1.96F0.04 is a promising cathode material for lithium-ion batteries for excellent electrochemical properties.展开更多
The performances of high power Er/Yb codoped fiber linear cavity lasers are investigated numerically. The numerical analysis is based on the iterative solution of rate equations for population density of the Er/Yb ion...The performances of high power Er/Yb codoped fiber linear cavity lasers are investigated numerically. The numerical analysis is based on the iterative solution of rate equations for population density of the Er/Yb ions. The behaviors of co-pump and counter-pump methods are contrasted. Dependence of output power on input pump power, output reflectivity, operating wavelength and active fiber length is simulated, respectively. High conversion efficiency Er/Yb laser output is obtained in simulations and experiments.展开更多
For energy storage system,it is still a huge challenge to achieve high energy density and high power density simultaneously.One potential solution is to fabricate electrochemical capacitors(ECs),which store electric e...For energy storage system,it is still a huge challenge to achieve high energy density and high power density simultaneously.One potential solution is to fabricate electrochemical capacitors(ECs),which store electric energy through surface ion adsorption or redox reactions.Here we report a new electrode material,heavy nitrogen-doped(9.29 at.%)black titania(TiO2-x:N).This unique hybrid material,consisting of conductive amorphous shells supported on nanocrystalline cores,has rapid N-mediated redox reaction(TiO2-xNy+zH++ze■-TiO2-xNyHz),especially in acidic solutions,providing a specific capacitance of 750 Fg-1at 2 m V s-1(707 Fg-1at 1 A g-1),great rate capability(503 F g-1at 20 Ag-1),and maintain stable after initial fading.Being a new developed supercapacitor material,nitrogen-doped black titania may revive the oxide-based supercapacitors.展开更多
基金Project(1114022-15) supported by the Major Science and Technology Research Projects of Guangxi Province,China
文摘The layered LiNi0.6Co0.2Mn0.2-yMgyO2-zFz（0≤y≤0.12, 0≤z≤0.08） cathode materials were synthesized by combining co-precipitation method and high temperature solid-state reaction, with the help of the ball milling, to investigate the effects of F-Mg doping on LiNi0.6Co0.2Mn0.2O）2. Compared with previous studies, this doping treatment provides substantially improved electrochemical performance in terms of initial coulombic efficiency and cycle performance. The LiNi0.6Co0.2Mn0.11Mg0.09O1.96F0.04 electrode delivers an high capacity retention of 98.6% during the first cycle and a discharge capacity of 189.7 m A·h/g（2.8-4.4 V at 0.2 C）, with the capacity retention of 96.3% after 100 cycles. And electrochemical impedance spectroscopy（EIS） results show that Mg-F co-doping decreases the charge-transfer resistance and enhances the reaction kinetics, which is considered to be the major factor for higher rate performance. It is demonstrated that LiNi0.6Co0.2Mn0.11Mg0.09O1.96F0.04 is a promising cathode material for lithium-ion batteries for excellent electrochemical properties.
基金National Natural Science Foundation of China ( 60137010 ) Tianjin Key Project Foundation of China(033183611)
文摘The performances of high power Er/Yb codoped fiber linear cavity lasers are investigated numerically. The numerical analysis is based on the iterative solution of rate equations for population density of the Er/Yb ions. The behaviors of co-pump and counter-pump methods are contrasted. Dependence of output power on input pump power, output reflectivity, operating wavelength and active fiber length is simulated, respectively. High conversion efficiency Er/Yb laser output is obtained in simulations and experiments.
基金financially supported by the National key R&D Program of China(2016YFB0901600)the Key Research Program of Chinese Academy of Sciences(QYZDJ-SSWJSC013)Chen IW was supported by U.S.Department of Energy BES grant DE-FG02-11ER46814used the facilities(Laboratory for Research on the Structure of Matter)supported by NSF grant DMR-1120901。
文摘For energy storage system,it is still a huge challenge to achieve high energy density and high power density simultaneously.One potential solution is to fabricate electrochemical capacitors(ECs),which store electric energy through surface ion adsorption or redox reactions.Here we report a new electrode material,heavy nitrogen-doped(9.29 at.%)black titania(TiO2-x:N).This unique hybrid material,consisting of conductive amorphous shells supported on nanocrystalline cores,has rapid N-mediated redox reaction(TiO2-xNy+zH++ze■-TiO2-xNyHz),especially in acidic solutions,providing a specific capacitance of 750 Fg-1at 2 m V s-1(707 Fg-1at 1 A g-1),great rate capability(503 F g-1at 20 Ag-1),and maintain stable after initial fading.Being a new developed supercapacitor material,nitrogen-doped black titania may revive the oxide-based supercapacitors.
