Preparation And Application Of Anode Materials For Metal Oxide/Graphene Lithium Ion Batteries

In recent years,the entire lithium battery industry chain will enter a new stage of development.The continuous development of the lithium battery industry can not only solve energy shortages and environmental pollution,but also promote the progress and development of human science and technology.In order to achieve this goal,the composites of binary Fe₃O₄-graphene and SnO₂-graphene composites as well as ternary SnO₂-Fe₃O₄-graphene were prepared by hydrothermal method.The morphology and structure of composite were characterized by XRD and SEM.The tests of constant current charge-discharge and AC impedance on batteries prepared by the composite samples were carried out in detail,in which the effect of different types（Fe₃O₄,SnO₂,SnO₂-Fe₃O₄）and different ratio of metal oxide doping on the structure and electrical properties of the anode material were focused on.Firstly,XRD analysis of the prepared composites showed that the metal oxides（Fe₃O₄,SnO₂,SnO₂-Fe₃O₄）and graphene were successfully prepared and perfectly combined,without obvious impurity peaks,indicating the preparation.The composite sample is of higher purity.SEM appearance analysis shows that the graphite oxide prepared by redox method has a sheet structure formed by expansion and reduction at high temperature.The metal oxides Fe₃O₄,SnO₂ and SnO₂-Fe₃O₄ crystal particles were distributed between the graphene layers.The composite of metal oxide and graphene is realized.Sheet-structured graphene facilitates storage of metal oxides and lithium ions.The metal oxide is evenly distributed between the graphene layers,which can effectively reduce the volume effect of the metal oxide and enhance the cycle performance of the metal oxide.The synergistic effect of graphene improves the electrical properties of the composite.Secondly,the electrical properties of the prepared composites show that the Fe3O4-graphene composite anode material has a first charge-discharge specific capacity of 1652 mAh/g at 0.1 C,and still reaches 1086 mAh/g after 30 cycles which was higher than the theoretical capacity of 924 mAh/g of Fe₃O₄.Even at 1.0C,the capacity of Fe₃O₄-graphene composite anode material can reach 780mAh/g.After30 cycles,and the capacity retention rate is 84.4%.The first generation of SnO₂-graphene composite anode material prepared by hydrothermal method has a discharge capacity of 1827.mAh/g.The capacity is still as high as 981 mAh/g higher than the theoretical capacity of SnO₂ of 782 mAh/g after 30 cycles.Even at 1.0C,the capacity after 30 cycles is 540 mAh/g,and the capacity retention rate is 69%.In order to further explore the lithium storage performance and cycle rate performance of Fe₃O₄-graphene and SnO₂-graphene,the SnO₂-Fe₃O₄-graphene composite was prepared by hydrothermal method,and its first charge and discharge capacity was up to 2354 mAh/g,after 30 cycles.The capacity is still as high as 1286 mAh/g.At 1.0C,the capacity is 981 mAh/g after 30 cycles,which is higher than the single metal oxide capacity.Therefore,the combination of metal oxide and graphene is to increase the metal oxide negative electrode.Effective means of material capacity and cycle stability.The experimental results show that the electrical properties of the graphene metal oxide composite anode material are significantly improved at the optimum reaction temperature and ratio.