电池正极材料Li3V2(PO4)3／C的水热合成和性能

Hydrothermal Synthesis and Electrochemical Characteristics of Cathode Materials Li_3V_2(PO_4)_3/C

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%.

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 investiga- ted. 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. cal properties of Li3V2（ PO4 ）3/C were investigated. The results show that the Li3V2（ PO4 ）3/C Electrochemi- 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 be- havior indicates that the Li3V2（ PO4 ）3/C material obtained by hydrothermal method has excellent capacity re- tention and rate capability.