Preparation & Lithium Storage Properties Performance Research Of V₂O₅@ Graphitized Carbon Nanofibers

Vanadium pentoxide?V₂O₅?has the highest theoretical rate capacity compared with commercial lithium ion battery cathode material.It is an ideal cathode material for lithium ion battery with low price and environmental protection.Unfortunately,the decent electrochemical performances of V2O5 has been hindered by the low theoretical rate capacity limited cycling stability,low rate capability,and short cycle life,which is ascribed to the inherent poor electronic conductivity and.low lithium ion diffusion coefficient.In this paper,V2O5 and graphitized porous carbon nanofibers were compounded to produce film cathode material with flexible free-standing structures and different morphologies,and lithium ion batteries Electrochemical Performance Research were studied.The main experimental contents are as follows:?1?In this paper,ferric oxide?FeO_x?was utilized to catalyze the graphitization of amorphous carbon and to serve as a template for the preparation of porous carbon materials.By means of electrostatic spinning,graphitized porous carbon nanofibers with excellent electrical conductivity were successfully prepared,and the conductance of graphitized carbon nanofibers is increased by 5×10⁴ times compared to the amorphous carbon.Through hydrothermal method with ammonium meta vanadate?NH₄VO₃?as the vanadium source and oxalic acid?H₂C₂O₄·2H₂O?as the solvent,the V2O5 nanosheets can be anchored on the surface of graphitized carbon nanofibers forming a flexible and free-standing composite electrode.The composite structure can be directly used as the cathodes of lithium ion battery for electrochemical performance test,which exhibit a reversible capacity of 290 mAh g^-1 at 0.1 C and a capacity higher than 105 mAh g^-1 even at a large current density of 20 C,retain a capacity of 160 mAh g^-1 at 5.0 C even over 700 cycles.?2?V₂O₅ nanoparticles were synthesized by hydrothermal method using the porous graphitized carbon nanofibers obtained in the above section,with triisopropanol vanadium oxide?VOTP?as the vanadium source and ethanol?EtOH?as the solvent.In the later heat treatment process,the gap between V₂O₅ nanosphere and the holes appears as the solvent volatilizes,which provided a space for the volume expansion of V2O5 nanoparticles and was conducive to maintaining the overall morphology of the composite material.The V₂O₅@porous carbon nanofiber film electrode with free-standing structure was used as the cathodes electrode of lithium ion battery for electrochemical performance test.Under the current density of0.1 C,the initial discharge capacity of the battery eached 290 mAh g^-1,and the capacity basically remained unchanged after 50 cycles.Through the cyclic performance test of 5.0 C,the initial discharge capacity reaches 200 mAh g^-1,and after 700 cycles,it can reach about 25%of the initial capacity,and a capacity higher than 50 mAh g^-1 even at a large current density of 20 C.