MoO3 /SiO2复合正极材料的制备及电化学性能研究

本文通过化学沉淀-热处理方法制备了MoO3正极材料,并通过正硅酸乙酯(TEOS)的水解在MoO3的表面包覆SiO2得到MoO3/SiO2复合正极材料wSiO2/wMoO3=8%],对制备材料的结构和电化学性能进行了表征。结果表明,得到的MoO3为纯的正交相结构,片状MoO3的粒径大小约200～500 nm,厚度约50 nm。片状颗粒倾向于堆积在一起形成层状结构。在MoO3的表面包覆了一层无定形的SiO2。在电压范围1.5～4.0 V的条件下,以0.1C倍率进行恒电流充放电测试,MoO3/SiO2样品的首次放电容量为332.7 mAh.g-1,库仑效率87.6%。循环20次后,放电容量降为277.7 mAh.g-1。SiO2的包覆降低了MoO3正极材料的初始容量,但循环性能得到了提高。

Preparation and Electrochemical Properties of MoO3 /SiO2 Composite Cathode Material for Lithium-Ion Batteries

MoO3 material was prepared by chemical precipitation and heat treatment method,and MoO3/SiO2 composite material was also prepared using MoO3 and Si(OC2H5)4 as the starting materials.The structural and morphological properties of the products were investigated by XRD,FT-IR,SEM and TEM.All the diffraction peaks from the pattern of MoO3 can be readily indexed to the pure phase of α-MoO3 with the orthorhombic structure.No peaks from other phases have been detected from the pattern of MoO3 /SiO2,indicating that SiO2 presents as amorphous material.The initial discharge capacity of MoO3 /SiO2 is 332.7 mAh.g-1 and coulombic efficiency is 87.6%.A discharge capacity of 277.7 mAh.g-1 is still obtained after 20 cycles,indicative of the good reversibility of Li+ intercalation/deintercalation reaction for MoO3/SiO2 electrode material.SiO2 coating over MoO3 can reduce the direct contact of electrode material with electrolyte and suppress the dissolution reaction of metal ions in electrode material.