通过三聚氰胺甲醛树脂(MR)中的羟基与石墨烯氧化物(GO)中的羧基发生的沉淀反应来制备功能化的氧化石墨烯前驱体,然后利用溶胶-凝胶及高温热处理方法制备磷酸钒锂/石墨烯复合材料,利用此材料制备了电池电极,并对电极材料进行了结构和电化学表征. 结果表明,所得磷酸钒锂为单斜晶系结构,石墨烯堆叠程度显著降低,也有效避免了磷酸钒锂颗粒的团聚,提高了材料的电化学性能. 电池的充放电曲线极化较小,在3.0~4.3 V的区间内20 C倍率仍有86 mA·h/g的可逆容量. 0.1 C循环100次后容量为119.7 mA·h/g,容量保持率94%. 在3.0~4.8 V的高电压区间,10 C倍率下可逆容量80 mA·h/g,0.1 C循环100次后仍有145.6 mA·h/g的可逆容量. 优异的循环和倍率性能以及较低的碳含量符合锂离子正极材料实用的要求.
Lithium vanadium phosphate(Li3V2(PO4)3)/reduced graphene oxide(rGO) composite has been successfully synthesized by incorporating melamine resin(MR) functionalized GO precursor into the Li3V2(PO4)3 solution and the subsequent heat treatment.The structural and electrochemical properties of Li3V2(PO4)3/rGO were characterized.The results show that Li3V2(PO4)3/rGO composite has monoclinic system, restacking of graphene layers and agglomeration of Li3V2(PO4)3 particles have been greatly inhibited, electrochemical performance of the composite has been improved.The as-obtained Li3V2(PO4)3/rGO was used as the cathode material in lithium ion batteries.The very low degree of polarization in the curve shows that electron and ion transports are facile, thus good rate and cycle behavior are observed.A considerably high lithiation capacity of 86 mA·h/g can be retained even at 20 C in the range of 3.0~4.3 V.After 100 cycles at 0.1 C, a discharge capacity of 119.7 mA·h/g could be delivered with the capacity retention of 94%.When the cells are operated between the voltage limits of 3.0~4.8 V vs.Li+/Li, a lithiation capacity of 80 mA·h/g at 10 C and 145.6 mA·h/g at 0.1 C after 100 cycles could be retained.Good cycling and rate performances, together with low carbon content, will be satisfactory for use as cathode material in lithium ion batteries.
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