锂离子电池正极材料LiFePO4的制备及电化学性能研究

∶采用高温固相法合成LiFePO4锂离子电池正极材料,为提高LiFePO4材料的电化学性能,对其进行Ti4 掺杂改性.用XRD、SEM等测试手段对材料进行表征,并对以Li1-xTixFePO4(x=0,0.01,0.03,0.05)为正极的电池进行电化学性能测试.研究表明,掺杂过程中,掺杂离子能与LiFePO4形成晶格完整、有序的单相固溶体;少量的掺杂离子还可以提高材料的电导率和电化学性能,特别是大电流放电性能,其中Li0.97Ti0.03FePO4性能最优,以0.2C5放电,首次放电质量比容量为132.0 mA.h/g,50次循环后仍保持为131.5 mA.h/g.

Synthesis and Electrochemical Analysis of LiFePO4 for Lithium-Ion Battery

To improve the performance of LiFePO4 as cathode material,composites Li1-xTixFePO4(x=0,0.01,0.03,and 0.05) with Ti4 dopant were synthesized by a solid-state reaction.The samples were characterized by X-ray diffraction(XRD),and scanning electron microscope(SEM),and their electrochemical properties were investigated by cyclic voltammeter(CV) and galvanostatic charge and discharge tests.The results indicate that the samples by doping Ti4 show a well-ordered olivine phase with no impurities;a little Ti4 dopant considerably improves the electrochemical performance of Li1-xTixFePO4,especially large current discharge behavior,which is ascribed to the enhancement of the electronic inductivity by ion doping.The Li0.97Ti0.03FePO4 shows the best electrochemical performance among Li1-xTixFePO4.At the 0.2C5 rate,the initial reversible specific capacity of the Li0.97Ti0.03FePO4 is 132.0 mAh/g,and remains 131.5 mAh/g after 50 cycles.