【摘要】 以LiOH.H2O,NH4VO3,NH4H2PO4和麦芽糖等为原料,采用水热法合成了碳包覆的磷酸钒锂化合物,考察了碳含量对材料电化学性能的影响.利用XRD,TEM,SEM和恒流充放电测试等手段对产物的结构、形貌和电化学性能进行表征.结果表明,在650℃煅烧的样品为单一纯相的单斜晶体结构.晶体颗粒分布为100～300 nm,粒度分散均匀,分散性良好,无团聚现象,且在颗粒表面包覆了一层无定形碳,这有利于改善材料的导电率.含碳量为10.23%的样品,在倍率1.0C的电流密度下,在3.0～4.3 V电压范围内,样品的首次放电比容量高达118.8 mA·h/g,循环15圈后放电比容量为115.1 mA·h/g,容量保持率为96.88%.更多还原

【Abstract】 A novel hydrothermal method was used to synthesize carbon-coated lithium vanadium phosphate compound.LiOH·H2O,NH4VO3,NH4H2PO4 and maltose without further purification were selected as starting materials to prepare precursor and the Li3V2(PO4)3/C which was obtained by sintering precursor at 650℃ for 2 h in flowing argon,and the effects of carbon content on electrochemical properties were investigated.The structural,morphology and electrochemical properties were investigated via X-ray diffraction(XRD),transmission electron microscopy(TEM),scanning electron microscopy(SEM) and constant current charge-discharge cycling.The compound synthesized at 650 ℃ took on pure monoclinic crystal structure,the particle size of the samples were ranged from 100 nm to 300 nm and there was a layer of carbon on the surface of Li3V2(PO4)3/C particles,which was available for enhancing the conductivity of Li3V2(PO4)3.Electrochemical properties of Li3V2(PO4)3/C were investigated.The results show that the Li3V2(PO4)3/C synthesized at 650 ℃ exhibits the highest initial discharge capacity of 118.8 mA·h/g and at the 15th cycle,the sample still keeps 115.1 mA·h/g at 1.0C in the voltage range of 3.0—4.3 V with 10.23% carbon contents.This behavior indicates that the Li3V2(PO4)3/C material obtained by hydrothermal method has excellent capacity retention and rate capability.更多还原