Research On Energy Storage Properties Of Vanadium-based Composites With Graphene

Due to the excessive use of resources and environment,the problem of resource shortage and environmental degradation is becoming more and more serious,it is urgent for mankind to develop a clean,efficient and renewable energy storage and converter device.Batteries are considered to be the most environmentally reliable energy storage device,so developing high-energy density and low cost battery system is extremely urgent.In this paper,we mainly based on the study of vanadium-based oxides and sulfide nanocomposite microstructure and the performances of electrochemical.In order to solve the shortcomings of the poor conductivity problems of the traditional transition metal oxides and sulfides,this paper used graphene foam?GF?as a high conductivity and flexibility substrate and successfully prepared with a nitrogen doped carbon coated GF+V₂O₅ nanoflakes arrays for lithium ion cathode material.Meanwhile prepared vertical nanosheets array composite of VS₂/GF through simple synthesis method.The the VS₂/GF vertical nanosheets array which can be not only used as a cathode material for lithium ion batteries but also can used as a negative electrode for sodium ion batteries,meanwhile both of them shows good cyclic stability.On the other hand,graphene foam?GF?was grown by chemical vapor deposition and GF was used as substrate material.The composite material of GF+V2O5 nanoscale array was grown by solvothermal method.Then,a layer of dopamine was coated with a layer of dopamine,and the GF+V₂O₅/N-C core shell array was prepared as the cathode material of the lithium ion battery.Because of the effect of conductive support of GF and the coating N-C layer,the GF+V₂O₅/N-C core shell array structure exhibits excellent cycling stability and rate performance.The discharge capacity under 1C can reach 293 mAhg-1,and the capacity retain of 223 mAhg-1 after 1000 cycles under5C.on the other hand,a one-step hydrothermal method is used to produce a vertical VS₂ nanosheets array on the GF,which is directly used as a flexible self-supporting electrode and is assembled into cathode of lithium ion battery and negative electrode of sodium ion battery without adding any conductive additive and adhesive.WhenVS₂/GF nanosheet array electrode is used as the cathode of lithium ion battery,after cycling for 200 cycles under 0.2C,the capacity was kept at the specific capacity of 110 mAhg^-1.As a negative electrode material of sodium ion battery,the charge and discharge test at high current density of 800 mAg^-1 still has 106 mAhg^-1 capacity retain.The preparation of flexible self-supporting electrode and the analysis of energy storage characteristics will provide theoretical guidance and experimental guidance for the design of new lithium ion battery,sodium ion battery and super capacitor.