用均相沉淀法制备NiO-石墨复合材料

为提高石墨作为负极材料的性能,首先以球形石墨为原料,KMnO4为氧化剂,浓H2SO4为插层剂制备氧化石墨;再分别以球形石墨、氧化石墨为原料,尿素为沉淀剂,采用均相沉淀法制备NiO/石墨复合材料。应用X射线衍射仪、扫描电子显微镜表征材料结构及形貌。结果表明,氧化后石墨的主特征峰发生了向左的大角度偏移,层面呈现片层结构。以球形石墨为原料制备的复合材料中NiO均匀性较差,团聚明显,特征峰半峰幅宽较小,晶粒较大;以氧化石墨为原料制备的复合材料中NiO均匀分布,无团聚,特征峰半峰宽较宽,晶粒较小。采用均相沉淀法对石墨进行NiO修饰有效提高了其容量及循环稳定性能。

Preparation of NiO/graphite composite by homogeneous precipitation method

This paper is focused on improving the performance of graphite anode.The improvement consists of the preparation of graphite oxide from spherical graphite as raw material,KMnO4 as oxidant,concentrated sulfuric acid as intercalation agent,and the preparation of NiO/graphite composite from spherical graphite,graphite oxide as raw material,urea as precipitant by homogeneous precipitation.XRD and SEM are used to characterize the composite＇s structure and morphology.Results show that after oxidation the main characteristic peak of graphite is subjected to a wide-angle offset in the left and presents lamellar structure.Compared with composite materials prepared from spherical graphite,which reveal poor uniformity of NiO,apparent aggregation,narrow characteristic peak＇s half-peak width,and larger grain size,composite materials prepared from graphite oxide boast a better uniformity of NiO,no aggregation,greater characteristic peak＇s half-peak width and smaller grain size.The modification of NiO/graphite composite by homogeneous precipitation method affords an effective improvement in capacity and cycling performance of the li-ion battery.