Preparation Of Lithium Ion Battery Anode Materials By Nano-carbon Materials Modified Natural Graphite

In this paper,on the basis of the reading extensive literature,natural graphite is modified by nano carbon materials for lithium ion battery anode materials,and have make systematic study about composite anode materias for high capacity,excellent rate performance and cycle stability.carbon nanotubes/natural graphite,carbon nanotubes/graphene/natural graphite anode material was prepared by sol gel.The morphology,structure and electrochemical properties of composite materials was characterized by SEM,TEM,XRD,FTIR and electrochemical performance test technologies.The calcination temperature,the ratio of carbon nanotubes and the proportion of graphene on the electrochemical properties of natural graphite were investigated.The following experimental results were obtained.Different sintering temperature(650?,700?,750?,800?)has great influence on microstructure and electrochemical properties of carbon nanotubes/nature graphite.At 650?,oxygen functional groups peaks was showed on the infrared spectra and XRD,while oxygen functional groups disappeared at 750?.In this paper,the optimum calcination temperature of the composite is 750?,and the charge/discharge capacity is as high as 409 and 417mAh/g at 0.1C,separately.The composite materials have good cycle performance and high rate performance.Proportion of carbon nanotubes(1%,3%,5%,7%,9%)has great influence on the morphology and electrochemical properties of CNT/NG composites.With the increse of CNTs-doped,the electrochemical properties of the sample would exprience the process that first increase and then decrease.The results showed that carbon nanotubes can form a perfect three-dimensional conductive network structure on the surface of natural graphite with 7%of CNTs,while the first charge and discharge specific capacity has 427 and 438 mAh/g at 0.1 C,separately,which was increased by 19%and 20%than that of natural graphite.And the composite materials has excellent the charge specific capacity with 427,417,408,417 and 345 mAh/g in 0.1C,0.2C,0.5 C,1C,2C current conditions,separately.Cycle stability and rate performance obviously improved.Graphene and carbon nanotubes modified natural graphite.Spatial coordinative interaction between graphene and carbon nanotubes can effectively prevent the agglomeration of CNTs and the accumulation of graphene layers.So that the network structure of the natural graphite surface are more smooth,builting numerous "conductive bridge" for lithium-ion transportment,which can further improved the electro-chemical performance.When the graphene amount of 4%,the samples have the best electrochemical performance.The charge and discharge specific capacity of composite materials are up to 470 and 479 mAh/g for the first time at 0.1C,coulomb efficiency was 98.1%.The charging specific capacity still has 442 mAh/g,and 94.0%retention capacity after the cycle of 100 times.And the composite materials has excellent the charge specific capacity with 470,456,433,405,355 mAh/g in 0.1C,0.2C,0.5 C,1C,2C current conditions,separately.The performance and cycle stability of carbon nanotubes/graphene/natural graphite are better that graphene/natural graphite,carbon nanotubes/natural graphite,natural graphite.