The spinel LiMn2O4 was made from Li2CO3 and MnO2 by combining the soft chemical treatment with the solid state reaction. The heating temperature was auto-controlled by program and the two-step treatment was adopted. T...The spinel LiMn2O4 was made from Li2CO3 and MnO2 by combining the soft chemical treatment with the solid state reaction. The heating temperature was auto-controlled by program and the two-step treatment was adopted. The synthesis mechanism of the spinel LiMn2O4 was studied by TGA-DTA analysis. It is found that the reaction of Li2CO3 and MnO2 will occur at the temperature lower than 600 ℃ and MnO2 has self-catalysis function during the reaction. The results of XRD and SEM to the synthesized materials show that the LiMn2O4 phase is pure, with regular appearance and uniform granularity distribution. The electrochemical tests indicate that the spinel LiMn2O4 has perfect cycling performances and the cycling capacity still keeps at 109.6 mA·h/g after 5 cycles.展开更多
LiOH.H2O,V2O5 and Y(NO3)3 were used as raw materials to synthesize the precursors containing Li,V and Y by liquid-state reaction,then the cathode materials Li1.05YxV3-xO8(x=0,0.002 5,0.005,0.01,0.02,0.1,0.2)for lithiu...LiOH.H2O,V2O5 and Y(NO3)3 were used as raw materials to synthesize the precursors containing Li,V and Y by liquid-state reaction,then the cathode materials Li1.05YxV3-xO8(x=0,0.002 5,0.005,0.01,0.02,0.1,0.2)for lithium-ion battery were obtained by calcining the precursors.The influence of Y3 +doping on structure,conductivity and electrochemical performance of Li1.05V3O8 were investigated by using XRD,cyclic voltammograms,AC impedance,etc.The results show that Li1.05YxV3-xO8 with different doping amounts have well-developed crystal structure of layered Li1.05V3O8 and lengthened interlayer distance of(100) crystal plane.Y3 + can insert into crystal lattice completely when the doping amount is small and the impurity phase of YVO4 is found when x≥0.1.There is no change in the process of Li+insertion-deinsertion with Y 3+doping.The conductivity is clearly improved due to small amount of Y 3+ doping and it tends to increase first and then decrease with increasing doping amount.The initial discharge capacity and plateau potential are both enhanced with proper amount of Y3 +doping.When x is 0.005,the first specific discharge capacity reaches 288.9 mA.h/g,4.60%larger than that of undoped sample(276.2 mA.h/g).When x≤0.1,the average discharge plateau potentials are enhanced by about 0.15 V,which makes for higher energy density.展开更多
基金Project(9810 3 0 0 70 4)supportedbyNaturalScienceFoundationofLiaoningProvince China projectsupportedbyQing haiScienceandTechnologyFund(2 0 0 2 G 10 2 )
文摘The spinel LiMn2O4 was made from Li2CO3 and MnO2 by combining the soft chemical treatment with the solid state reaction. The heating temperature was auto-controlled by program and the two-step treatment was adopted. The synthesis mechanism of the spinel LiMn2O4 was studied by TGA-DTA analysis. It is found that the reaction of Li2CO3 and MnO2 will occur at the temperature lower than 600 ℃ and MnO2 has self-catalysis function during the reaction. The results of XRD and SEM to the synthesized materials show that the LiMn2O4 phase is pure, with regular appearance and uniform granularity distribution. The electrochemical tests indicate that the spinel LiMn2O4 has perfect cycling performances and the cycling capacity still keeps at 109.6 mA·h/g after 5 cycles.
基金Project(2003224005)supported by the Liaoning Science and Technology Fund,China
文摘LiOH.H2O,V2O5 and Y(NO3)3 were used as raw materials to synthesize the precursors containing Li,V and Y by liquid-state reaction,then the cathode materials Li1.05YxV3-xO8(x=0,0.002 5,0.005,0.01,0.02,0.1,0.2)for lithium-ion battery were obtained by calcining the precursors.The influence of Y3 +doping on structure,conductivity and electrochemical performance of Li1.05V3O8 were investigated by using XRD,cyclic voltammograms,AC impedance,etc.The results show that Li1.05YxV3-xO8 with different doping amounts have well-developed crystal structure of layered Li1.05V3O8 and lengthened interlayer distance of(100) crystal plane.Y3 + can insert into crystal lattice completely when the doping amount is small and the impurity phase of YVO4 is found when x≥0.1.There is no change in the process of Li+insertion-deinsertion with Y 3+doping.The conductivity is clearly improved due to small amount of Y 3+ doping and it tends to increase first and then decrease with increasing doping amount.The initial discharge capacity and plateau potential are both enhanced with proper amount of Y3 +doping.When x is 0.005,the first specific discharge capacity reaches 288.9 mA.h/g,4.60%larger than that of undoped sample(276.2 mA.h/g).When x≤0.1,the average discharge plateau potentials are enhanced by about 0.15 V,which makes for higher energy density.