Transactions of Nonferrous Metals Society of China The Chinese Journal of Nonferrous Metals

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第15卷    第8期    总第77期    2005年8月

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刘素琴, 唐联兴, 黄可龙, 张 静

(中南大学 化学化工学院, 长沙 410083)

摘 要:  以LiOH·H2O、 V2O5和NH4H2PO4为原料, C为还原剂, 采用高温固相法合成了锂离子电池正极材料磷酸钒锂(Li3V2(PO4)3)。考察了合成温度等条件对产物组成和晶相的影响。 结果表明: 随着焙烧温度的升高, 杂相的衍射峰相对强度逐渐减弱, 当煅烧温度达到800 ℃时, 杂相衍射峰消失, 所得样品为纯相的Li3V2(PO4)3样品; 按Li、 V、 P的摩尔比为3∶2∶3将原料在800 ℃下焙烧24 h, 合成得到正极材料。 该材料在0.1 C充放电制度下, 首次充电比容量达到135 mA·h/g, 首次放电比容量130 mA·h/g, 充放电效率达96.3%; 经过20次循环后, 放电容量仍然高达110 mA·h/g。 对经过20次循环后的样品进行了X射线衍射分析,结果发现, 经过20次循环后样品仍然具有单斜晶体结构, 样品各主要衍射峰强度都急剧减弱, 说明样品在充放电过程中晶体结构发生了变化;采用最小二乘法对样品充放电前后的晶胞参数进行了计算, 发现样品在经过充放电循环后晶胞参数都有不同程度的增加, 晶胞体积增大0.6%左右。


关键词:  Li3V2(PO4)3;正极材料; NASCION结构

Synthesis and electrochemical characteristics of 
cathode materials Li3V2(PO4)3 for
lithium-ion batteries
LIU Su-qin, TANG Lian-xing, HUANG Ke-long, ZHANG Jing

School of Chemistry and Chemical Engineering,
Central South University, Changsha, 410083, China

Abstract: The cathode material Li3V2(PO4)3 was prepared by solid-state reaction of LiOH·H2O, V2O5 and NH4H2PO4, with carbon as the reduction agent. The effects of reaction conditions such as temperature on the structure were investigated by X-ray diffractrometry. The results show that the sample synthesized from the raw materials with molar ratio of Li, V and P of 3∶2∶3 at 800 ℃ for 24 h has a pure monoclinic crystal structure, which derives a initial discharge specific capacity of 130 mA·h/g. After charged/discharged at 0.1 C rate for 20 cycles, the sample retaines a discharge specific capacity of 110 mA·h/g. XRD patterns show that it retains monoclinic crystal structure, but the intensity of diffraction declines sharply. Least square method was used to calculate the unit-cell parameters of the sample before and after cycling, it is found that all of the parameters increase to some extend, and the unit-cell volume increases by 0.6%.


Key words: Li3V2(PO4)3; cathode materials; NASCION structure

ISSN 1004-0609
CN 43-1238/TG

ISSN 1003-6326
CN 43-1239/TG

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