LiV_3O_8/V_2O_5复合材料的制备与表征

Preparation and Characterizations of LiV_3O_8/V_2O_5 Composite Material

采用水热法制备了锂离子电池正极材料纯LiV3O8和LiV3O8/V2O5复合物,通过X射线衍射、扫描电子显微镜和比表面积测定等测试手段,对所制备样品的结构和形貌进行了表征和分析。结果表明,当n(Li)∶n(V)=1∶3.4时,所制备的复合物化学组成为LiV3O8·0.2V2O5,V2O5的掺杂增大了复合物中LiV3O8的层间距。SEM观察表明,纯LiV3O8样品由片状晶粒堆积形成聚集体,层间无空隙。而复合物中片状晶粒层间形成了大量的孔洞。复合物的多孔结构可望提高电解液在电极材料中的渗透程度,有利于锂离子的嵌脱反应。循环性能测试结果表明,复合物具有更高的初始放电容量和更好的循环性能。

Cathode materials for Li-ion batteries such as pure LiV3O8 and LiV3O8/V2O5 composite have been prepared by a hydrothermal reaction method. XRD, SEM and BET were employed to characterize the samples. The results show that the chemical formula of the as-prepared composite is LiV308 .0. 2V2O5. The interlayer distance of LiV3O8 in the composite is enhanced due to the existence of V2O5. SEM results show that pure LiV3O8 product consists of small laminar nanocrystallites that stacked together. While numerous cavities have been formed between the stacked laminar nanocrystallites in the composite. The porous structures in the composites can increase the penetration of electrolyte and therefore benefit the lithium intercalation/ deintercalation reaction. Charge-discharge cycling tests show that LiV3O8/V2O5 composite has a higher initial discharge capacity and better cycling performance compared with LiV3O8.