The Application Of Co₃?HCOO?₆@rGO Composite On The Anode Of Lithium-ion Battery

In recent years,with the growing maturity of the lithium-ion battery manufacturing process and the market,its application has gradually expanded to large-scale energy storage system.In order to realize high-performance lithium-ion battery,it is important to develop electrode material with high specific capacity,long cycle life and excellent rate performance at present.The metal ions and organic ligands of Metal-organic frameworks(MOFs)can serve as redox active centers,which make it possible be applied in the field of lithium-ion batteries.MOFs as a new kind of porous material,consisting of metal ions and organic ligands,has been applying in a variety of fields including gas storage,separation,drug delivery and sensing device.This paper focuses on the capacity of MOFs material CO3(HCOO)6-reduced graphene oxide(rGO)composite Co3(HCOO)6@rGO and Co3O4-rGO composite Co3O4@rGO derived from CO3(HCOO)6@rGO serving as the anode of lithium ion battery.The main content are listed as follows:1.Co3(HCOO)6@rGO composite was synthesized by in situ loading of CO3(HCOO)6 on rGO(reduced oxide graphene)through a solution chemistry method,and CO3(HCOO)6 was prepared through the same method.After the characterization of morphology and structure of Co3(HCOO)6@rGO and Co3(HCOO)6 materials,they were used as negative materials of lithium-ion batteries to study their battery performances,the results show that Co3(HCOO)6@rGO performed higher specific capacity and better rate performance than CO3(HCOO)6,Co3(HCOO)6@rGO shows potential application value.2.To reveal the origin of the significant differences in the performance of Co3(HCOO)6@rGO and CO3(HCOO)6 materials,we further explore the electrochemical reaction mechanism of these two materials.The morphology,structure and composition of Co3(HCOO)6@rGO and CO3(HCOO)6 materials during the charge-discharge process were investigated by electron microscopy,spectroscopy and electrochemical technologies.The results show that during the charge and discharge process,the structure of Co3(HCOO)6 collapsed,and both the Co2+ and formate ion in Co3(HCOO)6@rGO carry out reversible electrochemical reactions,while only Co2+ in Co3(HCOO)6 material carry out a conversion reaction.It was found that rGO can activate the electrochemical reaction of formate ion,as well as improve the Co3(HCOO)6 rate performance.3.The rGO supported Co3O4 composites(Co3O4@rGO)and Co3O4 were prepared by oxidative decomposition of Co3(HCOO)6@rGO and Co3(HCOO)6 materials as precursors at 350 ? in an air atmosphere.After the characterization of morphology and structure of Co3O4@rGO and Co3O4 materials,they were used as negative materials of lithium-ion batteries to study their battery performances.The results show that the Co3O4 particles on the Co3O4@rGO have good dispersibility,while rGO can buffer the volume expansion of Co3O4 during the charge-discharge process and improve the conductivity of the composite material,all of which can improve the reversibility of the conversion reaction,so that Co3O4@rGO performs better in cycle stability and rate performance than Co3O4.