SnO_2空心壳球材料及其碳包覆物的制备与性能表征

Preparation and Characterization of SnO2 Hollow Spheres and Their Carbon-coated Composites

采用水热合成法以SiO2微球为模板制备了SnO2空心壳球材料,并对其进行了碳包覆改性。采用XRD和SEM表征了所得材料的结构和表面形貌,并进一步研究了所得材料作为锂离子电池电极材料的电化学性能。XRD和SEM结果表明,所制备的SnO2空心壳球材料为四方相金红石结构,不含其它杂质,呈不规则壳球状形貌,经过碳包覆后呈规则球状,并且粒径变大;充放电和电化学阻抗谱结果显示,SnO2空心壳球材料首次充电容量达933mAh/g,80周循环以后可逆容量为382mAh/g;经过碳包覆的SnO2空心壳球材料,首次充电容量为908mAh/g,80周循环以后可逆容量仍高达654mAh/g,表明碳包覆可显著改善其电化学循环稳定性,这主要归因于碳包覆能够降低材料的界面阻抗。

A facile one-pot hydrothermal method, using SiO2 microspheres as a template, was developed to pre pare SnO2 hollow spheres and their carbon-coated composites. Their structure, morphology and electrochemical performance were investigated by XRD, SEM, discharge-charge test and electrochemical impedance spectroscopy. The XRD results show that SnO2 hollow spheres are tetragonal futile structure, without any inpurity. The SEM results show that the morphology of SnO2 appeared irregular spherical shell structure. After being coated by carbon, the spheres became larger than that of the oringin irregular balls with a relatively regular size. The results of discharge charge test and electrochemical impedance spectroscopy indicate that the first charge specific capacity of SnO2 hollow spheres reaches to 933mAh/g, which remains 382mAh/g after 80 circles. After being coated by carbon, the first charge specific capacity is 908mAh/g, which remains 654mAh/g after 80 circles, displaying that carbon coating can significantly improve SnO2 hollow spheres＇ electrochemical performance, due to the decrease of interface impedance of the materials by carbon coating.