Researches On The Structure And Electrochemical Properties Of Mo_xV_2-xO_5+y Nanomaterials

In response to the environmental pollution and fossil energy shortage and other issues,the development and application of energy storage devices are increasingly developed.Lithium-ion batteries,with higher energy density,the better retention ability,the widely use,fast charge and discharge and no memory effect,had been widely used in all aspects of life.As the core of lithium-ion battery components,electrode materials'effective modification is the most effective way to improve battery performance.In this study,based on the sol-gel method,the V₂O₅ was doped with Mo⁶⁺in the sol process,and the structure and properties of the prepared Mo_xV_2-xO_5+y+y were studied by changing the content of Mo⁶⁺.And the synthesis mechanism of Mo_xV_2-x-x O_5+y+y was discussed briefly.Meanwhile,combined graphene oxide with Mo_x V_2-xO_5+y,determined the effect of V⁴⁺on the structure and properties of the material.The main contents and results are as follows:The doping of Mo⁶⁺has a great effect on the structure of Mo_xV_2-x-x O_5+y.With the increase of Mo⁶⁺doping amount,the XRD results show that the V₃O₇ phase in the Mo_xV_2-xO_5+y+y material increased and the interplanar spacing increases slightly.The XPS analysis shows that the ratio of V⁴⁺increased from 13.8%of V₂O₅ to the 29.3%of Mo_0.04V_1.96.96 O_5+y;The FESEM and TEM images show that there are V₂O₅,V₃O₇,MoV₂O₈ and other phases on the nanosheets of Mo_xV_2-x-x O_5+y+y after the Mo⁶⁺doping.The formation mechanism of Mo_xV_2-xO_5+y+y nanomaterials is that the-OOH bond of the MoO₃ sol and the V₂O₅ sol group is broken during the sol-gel process,and the adjacent groups are connected to each other.Mo⁶⁺may replace V⁵⁺to form defect or connecting different V₂O₅ micelles embedded in the interlayer,thus forming intermolecular interconnection and interplanar spacing increased Mo_x V_2-xO_5+y+y nanomaterials.The Mo_xV_2-x-x O_5+y+y nanomaterials were used as electrode materials,and their electrochemical performance was tested.The following results were obtained:After the doped V₂O₅ electrode material has better structural stability and specific capacity,the initial discharge specific capacity of Mo_0.04V_1.96O_5+y+y is 223.8 mAhg^-1at a current density of 400 mAg^-1.And after 50 cycles,the discharge capacity is 145.3 mAhg^-1,the capacity retention rate is 64.9%,and the initial discharge specific capacity of V₂O₅ is 200.8 mAhg^-1.After 50 cycles,the specific capacity drops to 80.3 mAhg^-1,the capacity retention is only 40.0%.The ion transport rate exhibited by the Mo⁶⁺doped material is faster and the charge transfer resistance is significantly reduced.In order to understand the effect of V⁴⁺and Mo⁶⁺on the structure and properties of V₂O₅,graphene oxide was added in the preparation of Mo_x V_2-xO_5+y.The results showed that after adding 5 wt%graphene oxide to Mo_xV_2-xO_5+y.Under the combined action of Mo⁶⁺and graphene oxide,the content of V⁴⁺is greatly increased,and the change of V₂O₅?V₃O₇?V₆O₁₃?VO₂ occurs.When the amount of graphene addition is 10 wt%,the sample is V₆O₁₃,graphene oxide is converted to graphene and the nanometer material is coated.