【摘要】 采用溶胶凝胶法合成前驱体,再在空气气氛中分别于400℃、500℃和600℃下焙烧,得到锂离子电池正极材料Li(1-2x)MgxMnPO4/C(0≤x≤0.1);利用X射线衍射分析、环境扫描电镜分析、恒流充放电、阻抗测试等分析了产物的结构、形貌和电化学性能.结果表明,合成的Li(1-2x)MgxMnPO4/C颗粒呈球形,具有橄榄石结构;引入镁不改变其晶型,但使得其电化学性能得到改善.起始组成为x=0.03的样品的放电容量最高、循环性能最好;经空气气氛中400℃下焙烧后,其在2.8~4.4 V范围内、0.02 C下的放电容量达到128 mAh.g-1,经100次循环后容量保持在72 mAh.g-1.更多还原

【Abstract】 Li(1-2x) MgxMnPO4/C composite cathode materials for lithium ion batteries were synthesized by preparing precursors via sol-gel method and follow-up heat-treatment at 400 ℃,500 ℃ and 600 ℃ in air.The crystal structure and morphology of the products were investigated by means of X-ray diffraction and environmental scanning electron microscopy.The electrochemical performance of the products was measured by conducting galvanostatic charge-discharge test and alternating current impedance test.Results show that as-synthesized Li(1-2x) MgxMnPO4/C particulates have uniform spherical shape and consist of pure olivine-structured phase.The introduction of Mg had no effect on the crystal structure of LiMnPO4/C but contributed to improve the electrochemical performance.The sample with initial composition of x = 0.03 possessed the best electrochemical performance;it had a discharge capacity of 128 mAh·g-1 after being heated at 400 ℃ in air and tested at 0.02 C rate,and the discharge capacity was maintained at 72 mAh·g-1 after 100 cycles.更多还原