Co_3(HCOO)_6@rGO作为锂离子电池负极材料的研究

Co_3(HCOO)_6@rGO as a Promising Anode for Lithium Ion Batteries

MOFs材料作为一类新型的锂离子电池电极材料而受到广泛关注和研究.作者通过溶液扩散法将Co_3(HCOO)_6原位负载在rGO(还原氧化石墨烯)上制备出Co_3(HCOO)_6@rGO复合材料.将Co_3(HCOO)_6@rGO作为锂离子电池负极材料,以500 mA·g^(-1)的电流密度恒电流充放电循环100周后,仍然保持有926 mAh·g^(-1)的比容量,亦表现出很好的倍率性能.循环伏安和X-射线光电子能谱测试表明,Co_3(HCOO)_6@rGO材料上的Co^(2+)和甲酸根在充放电过程中均发生可逆的电化学反应.对比同样采用溶液扩散法合成的Co_3(HCOO)_6的测试结果发现,rGO起到活化甲酸根的电化学反应的作用,同时也改善了Co_3(HCOO)_6的倍率性能.将MOFs材料与rGO复合为优化MOFs材料的电池性能提供了一个新思路.

Metal-organic framework（MOF） is a kind of novel electrode materials for lithium ion batteries. Here, a composite material Co3（HCOO）6@rGO was synthesized for the first time by in situ loading of Co3（HCOO）6 on rGO（reduced oxide graphene）through a solution chemistry method. As an anode material for lithium ion batteries, it exhibited an excellent cycle stability as well as a large reversible capacity of 926 mAh·g^-1 at a current density of 500 mA·g^-1 after 100 cycles within the voltage range of 0.02 ~3.0 V vs. Li/Li＋ with a good rate capability. The results of cyclic voltammetry and XPS measurements revealed that both Co^2＋ and formate ions in Co3（HCOO）6@rGO underwent reversible electrochemical reactions during the charge and discharge processes.Compared with Co3（HCOO）6 synthesized through the same method, it was found that rGO could activate the electrochemical reaction of formate ion, which improved the Co3（HCOO）6 rate performance. A new route was demonstrated through this work to enhance the specific capacity and rate capability of MOFs by introducing rGO.