磷酸钒锂与磷酸铁锂正极材料改性研究进展

Research Progresses in the Modification of Lithium Vanadium Phosphate and Lithium Iron Phosphate Cathode Materials

作为聚阴离子型的电极材料,磷酸钒锂与磷酸铁锂具有很强的对比性。本文从四个方面对这两种材料进行了改性论述:碳包覆、离子掺杂、复合离子掺杂和粒子纳米化。然后对所改善的电化学性能进行了比较。结果表明碳包覆和纳米化改性后的高倍率性能都有很大提升。但是掺杂金属离子的结果却不尽相同:磷酸钒锂掺锰改善的是库伦效率,磷酸铁锂掺锰的改善结果不明显。同样是掺杂镍,磷酸钒锂改善的是放电容量,磷酸铁锂改善的是高倍率放电性能。我们认为改善结果的不同与铁、钒本身的化学性质或者磷酸铁锂、磷酸钒锂本身的结构有关。

Both lithium iron phosphate and lithium vanadium phosphate belong to the polyanion cathode materials,so the comparison of these two materials is meaningful.This paper compared the electrochemical properties of these two materials that after modified in four fields：carbon coating,ion doping,doping in composite and nano particle size.The results showed that both the carbon coating and nano particle modified improved the high-rate charge-discharge performance obviously.However,doping metal ions have different results：Lithium vanadium phosphate doped manganese enhanced its coulomb efficiency,lithium iron phosphate doped manganese haven＇t found obvious evidence in the results.Doped nickel in these two materials,vanadium lithium phosphate＇s discharge capacity enhanced while the lithium iron phosphate behaved with a high-rate discharge performance.We think the difference is related to the chemical properties of vanadium and iron or the structure of the lithium iron phosphate and lithium vanadium phosphate.