锂离子电池正极材料Li1-xVxCryFe1-yPO4／C的制备及电化学性能的研究

Preparation of Li_(1-x)V_xCr_yFe_(1-y)PO_4/C and study on its electrochemical performances

采用高温固相法合成了Li1-xVxCryFe1-yPO4/C(x=0.01、0.02;y=0.01、0.02)锂离子电池正极材料,通过XRD、SEM、C-V和恒电流充放实验研究了不同掺杂量对产物结构和电化学性能的影响。研究表明,少量V和Cr的掺杂未影响到LiFePO4的晶体结构,但显著改善了它的电化学性。其中,Li0.99V0.01Cr0.02Fe0.98PO4/C材料具有更好的电化学性能,0.1C倍率放电时,首次放电容量达到163.8mAh/g,且循环性能良好。另外,对合成材料的红外光谱进行了研究和指认。

Composites Li1-xVxCryFe1-yPO4/C （x=0. 01,0. 02; y=0. 01,0. 02） were synthesized by high temperature solid state reaction method. The samples were characterized by X-ray diffraction（XRD） and scanning electron microscope（SEM）, and their electrochemical performances were investigated including cycling behavior （C- V） and constant current charge-discharge experiment. The results indicate that the low concentration V and Cr dopant does not affect the structure of LiFePO4 but considerable improves its electrochemical performances. The Li0.99V0.01Cr0.02Fe0.98 PO4/C material showed better electrochemical performances than LiFePO4. At 0. 1C discharging rate, it is capable of delivering reversible specific capacity of 163.8mAh/g, with fairly stable cycleability. In addition, FT-IR spectroscopic studies for these materials were carried out and the vibrational bands were assigned.