锂离子电池正极材料LiMn_yFe_(1-y)PO_4的制备及性能研究

Synthesis and Performances of LiMn_yFe_(1-y)PO_4 as Cathode Materials for Lithium-ion Batteries

采用高速球磨与高温固相反应相结合的方法合成了LiMnyFe1-yPO4(0．1≤y≤1．0)锂离子电池正极材料,并对其晶体结构、表观形貌和电化学性能进行了研究．结果表明,所合成的 LiMnyFe1-yPO4为单一橄榄石型结构,粒径分布较均匀．当以小电流密度(0．1C)充放电时, LiMn0．1Fe0．9PO4具有最高的放电比容量,为145mAh／g;LiMn0．6Fe0．4PO4质量比能量最高, 达568Wh／kg．LiMnyFe1-yPO4的倍率放电性能随着y的增加而降低,这主要是材料在4．0V 平台的容量损失造成的;LiMn0．1Fe0．9PO4具有最佳的倍率性能:以0．5、1．5C倍率进行放电,放电容量分别达到130、109mAh／g．

The LiMnyFe1-yPO4 （0.1≤ y≤1） cathode materials for lithium-ion batteries were synthesized by solid-state reaction combined with high-rate ball milling. The crystalline structure, morphology of particles, and electrochemical performance of the sample were investigated by X- ray diffraction, scanning electron microscope, charge-discharge test and cyclic voltammetry. The results show that all LiMnyFe1-yPO4 samples are simple pure olive-type phase with small particles, and uniformly distribution of gain sizes. At low rate of 0.1C, the first specific discharge capacity of LiMn0.1Fe0.9PO4 is the highest with 145mAh/g and LiMn0.6Fe0.4PO4 shows the highest energy density of 568Wh/kg. The rate capabilities of the samples are strongly influenced by y value of LiMnyFe1-yPO4. LiMn0.1Fe0.9PO4 shows the best rate capabilities with discharge capacity of 130mAh/g at 0.5C rate and 109mAh/g at 1.5C rate.