LiVO_(3)/石墨烯复合材料制备及电化学性能研究

Synthesis and Electrochemical Performance of LiVO_(3)/Graphene Composite

为提高LiVO_(3)的电化学性能,通过简易溶液法制备了一系列LiVO_(3)/石墨烯(质量分数分别为0,3%,5%,7%)复合材料。借助X射线衍射(XRD)、扫描电镜(SEM)、电化学交流阻抗测试(EIS)、恒电位间隙滴定(GITT)等表征技术,考察石墨烯包覆以及石墨烯的含量对LiVO_(3)的晶体结构、微观形貌和电化学性能的影响。结果表明:通过溶液法可实现石墨烯包覆,石墨烯包覆能细化晶粒;随着石墨烯含量的增大,样品颗粒尺寸减小,锂离子扩散系数增大,材料电子导电率提高,因而LiVO_(3)/石墨烯复合材料的倍率性能和循环性能都有一定程度的提升。石墨烯质量分数为5%的样品LVO/Gr-3综合性能最优,首次放电容量可达338 mAh/g,在200 mA/g的电流下循环100次,容量保持率为71.4%。

LiVO_(3) is a promising cathode material for lithium ions batteries with high capacity.By simple solution method,a series of LiVO_(3)/grapheme composites(wt=3%,5%,7%)are prepared.XRD,SEM,EIS and GITT are used to investigate the crystal structure,morphology and electrochemical performance of bare LiVO_(3) and LiVO_(3)/grapheme composites.The results indicate that graphene enhances electrochemical performance of LiVO_(3) by increasing its electronic conductivity and ion conductivity.The LiVO_(3)/grapheme(5%wt)shows best performance,which is 338mAh/g initial discharge capacity and 71.4%capacity retention after 100 cycles at the current density of 200 mA/g.