石墨烯包覆 LiFePO4共沉淀-焙烧法制备及性能研究

摘要

以氧化石墨烯和抗坏血酸为包覆碳源，采用共沉淀-焙烧法制备了 LiFePO4/ G 和 LiFePO4/ C 正极材料，并通过 X -射线衍射图谱（XRD），扫描电镜（SEM）对合成材料进行结构及形貌分析，并采用循环伏安（CV）、恒电流充放电等表征手段对合成材料进行电化学性能测试。结果表明，石墨烯和碳颗粒的引入没有改变 LiFePO4橄榄石晶体结构，石墨烯在细化颗粒和均匀分布上的效果优于普通碳颗粒，使 LiFePO4/ G 表现出更加优越的电化学性能，在0.1C 倍率时的放电容量为134 mAh·g -1，充放电循环20次后容量保持率可达到98.8％。%Graphene oxide and L - ascorbic acid were used as carbon - coating sources for the synthesis of LiFePO4 / G and LiFePO4 / C cathode materials via a co - precipitation - calcination method. XRD and SEM were available for the characterization of the morphology and structure,CV and galvanostatic discharge - charge tests were used to test the electrochemistry properties. The results indicated that the introduction of graphene sheets and carbon particles did not change the olivine crystal structure,graphene sheets were more effective than carbon particles on deriving fine and uniform particles,which showed the excellent electrochemistry performances of LiFePO4 / G compared with LiFePO4 / C,and the initial discharge capacity of LiFePO4 / G at 0. 1C was 134mAh·g - 1;After 20 cycles,the capacity retention was 98. 8% of the initial discharge capacity.