A supercritical hydrothermal method was employed to prepare sub-micrometer LiFePO4particles with high purity and crystallinity.The structure and morphology of LiFePO4particles were characterized by X-ray diffraction a...A supercritical hydrothermal method was employed to prepare sub-micrometer LiFePO4particles with high purity and crystallinity.The structure and morphology of LiFePO4particles were characterized by X-ray diffraction and scanning electron microscope.The electrochemical tests were carried out to determine the reversible capacity,rate and cycling performance of the LiFePO4particles as cathode material for lithium ion battery.Experimental results show that solvent and calcining time have significant effects on purity,size and morphology of LiFePO4particles.Mixed solvent contained deionized water and ethanol is conducive to synthesize smaller and more uniform particles.The size of LiFePO4particles as-prepared is about 100-300 nm.The specific discharge capacities of the LiFePO4particles are 151.3 and 128.0 mA·h·g?1 after first cycle at the rates of 0.1 and 1.0 C,respectively.It retains 95.0%of the initial capacity after 100 cycles at 1.0 C.展开更多
In this study,sub-micrometer LiFePO_4 particles with high purity and crystallinity were synthesized using supercritical hydrothermal method as the cathode material for lithium ion batteries.Experimental results show t...In this study,sub-micrometer LiFePO_4 particles with high purity and crystallinity were synthesized using supercritical hydrothermal method as the cathode material for lithium ion batteries.Experimental results show that templates and calcination time have significant impacts on the purity,particle size and morphology of LiFePO_4 particles.The as-prepared LiFePO_4 particles using polyvinyl pyrrolidone(PVP) template with additional one hour calcination at 700℃exhibit characteristics of good crystallinity,uniform size distribution,high capacity and cycling performance.The specific discharge capacities of 141.2 and 114.0mA·h/g were obtained at the charge/discharge rates of 0.1 and 1.0 C,respectively.It retained 96.0%of an initial capacity after 100 cycles at 1.0 C rate.The good electrochemical performance of the as-synthesized material is attributed to the synergistic factors of its reasonable particle size and surface areas and high crystallinity.展开更多
Lithium iron phosphate (LiFePO4) was synthesized from LiOH, FeSO4 and H3PO4 by a hydrothermal process at 180℃. The samples were characterized by X-ray diffraction, scanning electron microscopy and chemical analysis. ...Lithium iron phosphate (LiFePO4) was synthesized from LiOH, FeSO4 and H3PO4 by a hydrothermal process at 180℃. The samples were characterized by X-ray diffraction, scanning electron microscopy and chemical analysis. Electrochemical performance of the samples was tested in terms of charge-discharge capacity and cycling behavior. The results indicated that Fe(III) impurity had obvi- ously effect on the electrochemical properties of LiFePO4, and the formation of Fe3+ was caused by the oxidation of Fe2+ in the dissolving and feeding processes accompanying the increase of pH value. It was found that the precipitation separation was effective in decreasing the content of Fe3+ in the solu- tion of FeSO4 and the sealed feeding was useful in preventing the conversion of Fe2+ to Fe3+. When the content of Fe3+ < 0.5 wt%, the hydrothermally synthesized LiFePO4 calcined at 750℃ with sucrose as carbon source exhibited an initial discharge capacity of 154.9 mAh·g-1 at the rate of 0.1 C (1 C = 150 mA·g-1) and the cycling retention rate could reach 98% after 50 cycles at room temperature.展开更多
文摘A supercritical hydrothermal method was employed to prepare sub-micrometer LiFePO4particles with high purity and crystallinity.The structure and morphology of LiFePO4particles were characterized by X-ray diffraction and scanning electron microscope.The electrochemical tests were carried out to determine the reversible capacity,rate and cycling performance of the LiFePO4particles as cathode material for lithium ion battery.Experimental results show that solvent and calcining time have significant effects on purity,size and morphology of LiFePO4particles.Mixed solvent contained deionized water and ethanol is conducive to synthesize smaller and more uniform particles.The size of LiFePO4particles as-prepared is about 100-300 nm.The specific discharge capacities of the LiFePO4particles are 151.3 and 128.0 mA·h·g?1 after first cycle at the rates of 0.1 and 1.0 C,respectively.It retains 95.0%of the initial capacity after 100 cycles at 1.0 C.
基金the Fundamental Research Funds for the Central Universities of China(No.DUT11NY08)
文摘In this study,sub-micrometer LiFePO_4 particles with high purity and crystallinity were synthesized using supercritical hydrothermal method as the cathode material for lithium ion batteries.Experimental results show that templates and calcination time have significant impacts on the purity,particle size and morphology of LiFePO_4 particles.The as-prepared LiFePO_4 particles using polyvinyl pyrrolidone(PVP) template with additional one hour calcination at 700℃exhibit characteristics of good crystallinity,uniform size distribution,high capacity and cycling performance.The specific discharge capacities of 141.2 and 114.0mA·h/g were obtained at the charge/discharge rates of 0.1 and 1.0 C,respectively.It retained 96.0%of an initial capacity after 100 cycles at 1.0 C rate.The good electrochemical performance of the as-synthesized material is attributed to the synergistic factors of its reasonable particle size and surface areas and high crystallinity.
文摘Lithium iron phosphate (LiFePO4) was synthesized from LiOH, FeSO4 and H3PO4 by a hydrothermal process at 180℃. The samples were characterized by X-ray diffraction, scanning electron microscopy and chemical analysis. Electrochemical performance of the samples was tested in terms of charge-discharge capacity and cycling behavior. The results indicated that Fe(III) impurity had obvi- ously effect on the electrochemical properties of LiFePO4, and the formation of Fe3+ was caused by the oxidation of Fe2+ in the dissolving and feeding processes accompanying the increase of pH value. It was found that the precipitation separation was effective in decreasing the content of Fe3+ in the solu- tion of FeSO4 and the sealed feeding was useful in preventing the conversion of Fe2+ to Fe3+. When the content of Fe3+ < 0.5 wt%, the hydrothermally synthesized LiFePO4 calcined at 750℃ with sucrose as carbon source exhibited an initial discharge capacity of 154.9 mAh·g-1 at the rate of 0.1 C (1 C = 150 mA·g-1) and the cycling retention rate could reach 98% after 50 cycles at room temperature.
