The uniform layered Li(Ni1/3Co1/3Mn1/3)O2 cathode material for lithium-ion secondary batteries were synthesized by using(Ni1/3Co1/3Mn1/3)(OH)2 synthesized by a liquid phase co-precipitated method as precursors and wit...The uniform layered Li(Ni1/3Co1/3Mn1/3)O2 cathode material for lithium-ion secondary batteries were synthesized by using(Ni1/3Co1/3Mn1/3)(OH)2 synthesized by a liquid phase co-precipitated method as precursors and with NiSO4,CoSO4,MnSO4 and NH3·H2O as raw materials. The influence of the preparation conditions such as precursors preparation,calcinations temperature and calcinations time on the structural and electrochemical properties of the Li(Ni1/3Co1/3Mn1/3)O2 were systematicelly studied. The result of XRD shows the I003/I104 value of the Li(Ni1/3Co1/3Mn1/3)O2 powder synthesized at 950 ℃ for 10 h is 1.26,which illustrates the well-ordered layer-structure. The average particle size of uniform Li(Ni1/3Co1/3Mn1/3)O2 powder is about 400 nm in diameter as observed by scanning electron microscopy. The first discharge capacity of Li(Ni1/3Co1/3Mn1/3)O2 electrode is 174.6 mA·h/g at 16 mA/g between 2.8 V and 4.5 V versus Li at room temperature,and the capacity retention is 95.2% of the initial discharge capacity after 50 cycles at 32 mA/g.展开更多
Mesoporous LiFePO4/C microspheres consisting of LiFePO4 nanoparticles are successfully fabricated by an eco-friendly hydrothermal approach combined with high-temperature calcinations using cost-effective LiOH and Fe3...Mesoporous LiFePO4/C microspheres consisting of LiFePO4 nanoparticles are successfully fabricated by an eco-friendly hydrothermal approach combined with high-temperature calcinations using cost-effective LiOH and Fe3＋ salts as raw materials.In this strategy,pure mesoporous LiFePO4 microspheres,which are composed of LiFePO4 nanoparticles,were uniformly coated with carbon（1.5nm）.Benefiting from this unique architecture,these mesoporous LiFePO4/C microspheres can be closely packed,having high tap density.The initial discharge capacity of LiFePO4/C microspheres as positive-electrode materials for lithium-ion batteries could reach 165.3 mAh/g at 0.1 C rate,which is notably close to the theoretical capacity of LiFePO4 due to the large BET surface area,which provides for a large electrochemically available surface for the active material and electrolyte.The material also exhibits high rate capability（100 mAh/g at 8 C） and good cycling stability（capacity retention of 92.2%after 400 cycles at 8 C rate）.展开更多
LiFePO4/C composites with good rate capability and high energy density were prepared by adding sugar to the synthetic precursor. A significant improvement in electrode performance was achieved. The resulting carbon co...LiFePO4/C composites with good rate capability and high energy density were prepared by adding sugar to the synthetic precursor. A significant improvement in electrode performance was achieved. The resulting carbon contents in the sample 1 and sample 2 are 3.06% and 4.95%（mass fraction）, respectively. It is believed that the synthesis of LiFePO4 with sugar added before heating is a good method because the synthesized particles having uniform small size are covered by carbon. The performance of the cathodes was evaluated using coin cells. The samples were characterized by X-ray diffraction and scanning electron microscope observation. The addition of carbon limits the particles size growth and enables high electron conductivity. The LiFePO4/C composites show very good electrochemical performance delivering about 142 mAh/g specific capacity when being cycled at the C/10 rate. The capacity fade upon cycling is very small.展开更多
文摘The uniform layered Li(Ni1/3Co1/3Mn1/3)O2 cathode material for lithium-ion secondary batteries were synthesized by using(Ni1/3Co1/3Mn1/3)(OH)2 synthesized by a liquid phase co-precipitated method as precursors and with NiSO4,CoSO4,MnSO4 and NH3·H2O as raw materials. The influence of the preparation conditions such as precursors preparation,calcinations temperature and calcinations time on the structural and electrochemical properties of the Li(Ni1/3Co1/3Mn1/3)O2 were systematicelly studied. The result of XRD shows the I003/I104 value of the Li(Ni1/3Co1/3Mn1/3)O2 powder synthesized at 950 ℃ for 10 h is 1.26,which illustrates the well-ordered layer-structure. The average particle size of uniform Li(Ni1/3Co1/3Mn1/3)O2 powder is about 400 nm in diameter as observed by scanning electron microscopy. The first discharge capacity of Li(Ni1/3Co1/3Mn1/3)O2 electrode is 174.6 mA·h/g at 16 mA/g between 2.8 V and 4.5 V versus Li at room temperature,and the capacity retention is 95.2% of the initial discharge capacity after 50 cycles at 32 mA/g.
文摘Mesoporous LiFePO4/C microspheres consisting of LiFePO4 nanoparticles are successfully fabricated by an eco-friendly hydrothermal approach combined with high-temperature calcinations using cost-effective LiOH and Fe3＋ salts as raw materials.In this strategy,pure mesoporous LiFePO4 microspheres,which are composed of LiFePO4 nanoparticles,were uniformly coated with carbon（1.5nm）.Benefiting from this unique architecture,these mesoporous LiFePO4/C microspheres can be closely packed,having high tap density.The initial discharge capacity of LiFePO4/C microspheres as positive-electrode materials for lithium-ion batteries could reach 165.3 mAh/g at 0.1 C rate,which is notably close to the theoretical capacity of LiFePO4 due to the large BET surface area,which provides for a large electrochemically available surface for the active material and electrolyte.The material also exhibits high rate capability（100 mAh/g at 8 C） and good cycling stability（capacity retention of 92.2%after 400 cycles at 8 C rate）.
文摘LiFePO4/C composites with good rate capability and high energy density were prepared by adding sugar to the synthetic precursor. A significant improvement in electrode performance was achieved. The resulting carbon contents in the sample 1 and sample 2 are 3.06% and 4.95%（mass fraction）, respectively. It is believed that the synthesis of LiFePO4 with sugar added before heating is a good method because the synthesized particles having uniform small size are covered by carbon. The performance of the cathodes was evaluated using coin cells. The samples were characterized by X-ray diffraction and scanning electron microscope observation. The addition of carbon limits the particles size growth and enables high electron conductivity. The LiFePO4/C composites show very good electrochemical performance delivering about 142 mAh/g specific capacity when being cycled at the C/10 rate. The capacity fade upon cycling is very small.
