摘要
The layered compound Li(Ni0.5Mn0.5)1?xTixO2 powders were prepared with Ni(OH)2,MnCO3,Li2CO3 and TiO2 by one-step solid state reaction.The effect of doping Ti on the structure and electrochemical properties was studied.The XRD results indicate that the powders with 0≤x≤0.05 have good layered structure and trace of impurity appears in the samples with x≥0.1.The SEM photographs show that the particle size distributes homogeneously and the sample with x=0.15 has larger particle size than other samples.The charge-discharge tests show that Li(Ni0.5Mn0.5)0.95Ti0.05O2 synthesized at 800 ℃ for 36 h exhibits good electrochemical properties.It firstly delivers 173 mA·h/g and maintains 90% of the initial discharge capacity after 30 cycles.The cyclic voltammetry and differential capacity vs voltage curves show that the major oxidation and reduction peaks are around 3.95 V and 3.75 V,respectively,assigned to Ni2+/Ni4+ oxidation-reduction process.A weak peak around 4.5 V is found during the oxidation process in the first cycle,which can be regarded as the main reason of the large drop of discharge capacity in the initial cycle.
The layered compound Li(Ni0.5Mn0.5)1?xTixO2 powders were prepared with Ni(OH)2,MnCO3,Li2CO3 and TiO2 by one-step solid state reaction.The effect of doping Ti on the structure and electrochemical properties was studied.The XRD results indicate that the powders with 0≤x≤0.05 have good layered structure and trace of impurity appears in the samples with x≥0.1.The SEM photographs show that the particle size distributes homogeneously and the sample with x=0.15 has larger particle size than other samples.The charge-discharge tests show that Li(Ni0.5Mn0.5)0.95Ti0.05O2 synthesized at 800 ℃ for 36 h exhibits good electrochemical properties.It firstly delivers 173 mA·h/g and maintains 90% of the initial discharge capacity after 30 cycles.The cyclic voltammetry and differential capacity vs voltage curves show that the major oxidation and reduction peaks are around 3.95 V and 3.75 V,respectively,assigned to Ni2+/Ni4+ oxidation-reduction process.A weak peak around 4.5 V is found during the oxidation process in the first cycle,which can be regarded as the main reason of the large drop of discharge capacity in the initial cycle.
基金
Project supported by the Postdoctoral Science Foundation of Central South University,China
