碳热还原法合成Mg掺杂LiFePO_4/C正极材料及电化学性能研究

Synthesis and electrochemical characterizations of Mg-doped LiFePO_4/C by carbothermal reduction

利用碳热还原法合成了Li1-xMgxFePO4/C(x=0.00、0.01、0.02、0.03、0.04、0.05、0.1)正极材料,通过XRD、SEM、BET、CV、EIS和恒流充放电实验研究了不同掺杂量对产物结构和电化学性能的影响。结果表明少量Mg的掺杂未影响到LiFePO4的晶体结构,但显著改善了其电化学性能。其中,Li0.98Mg0.02FePO4/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165.2mAh/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-xMg, FePO4/C （x=0.00,0.01,0.02,0.03,0.04,0.05,0.1） were synthesized by carbothermal reduction method. The samples were characterized by X-ray diffraction （XRD） and scanning electron microscope（SEM）, and their electrochemical performances were investigated by analyses of cyclic voltammetry （CV）, electrochemical impedance spectra（EIS） and constant current charge-discharge experiment. The results indicate that the low concentration Mg dopant does not affect the structure of LiFePO4 but considerable improves its electrochemical performances. The Li0.98 Mg0.02 FePO4/C materials showed better electrochemical performances than LiFePO4. At 0. 1C discharging rate, it is capable of delivering reversible specific capacity of 165.2mAh/g, with fairly stable cycleability. In addition, FT-IR spectroscopic studies for these materials were carried out and the vibrational bands were assigned.