Preparation And Electrochemical Properties Of Graphene/manganese Dioxide Composites

Supercapacitor is a new concept energy storage device that combines the advantages of battery and traditional capacitors.It has the advantages of fast charge and discharge speed,high charge and discharge efficiency,high energy density,long cycle life,wide operating temperature range and green environmental protection.It is widely used in transportation,industry,renewable energy,military and other fields.The combination of conductive graphene and high specific capacity manganese dioxide,the synergistic effect of the composite material makes the composite material combine the advantages of graphene and manganese dioxide to make up for the shortcomings of single material.In this paper,the modified Hummers method was used to synthesize graphite oxide?GO?,and L-ascorbic acid was used to reduce graphene oxide to obtain reduced graphene oxide?rGO?.KMnO₄,SDS and graphene oxide were used as raw materials to control reaction time,KMnO₄ and SDS.The addition amount was unchanged,and the addition amount of graphene oxide was changed to prepare different content of graphene/manganese dioxide composite materials.The reduced graphene oxide,KMnO₄ and SDS were used as raw materials.By controlling the reaction time and the amount of graphene solution,the content of KMnO₄ and SDS was changed to prepare different content of graphene/manganese dioxide composite.The structure and morphology of the composites were characterized by XRD and SEM,and their electrochemical properties were studied.1.When graphene/manganese dioxide composite is prepared by using graphene oxide,potassium permanganate or SDS as raw materials,the amount of graphene oxide added is 0.05g,the amount of potassium permanganate added is 0.5g,and the amount of SDS added is The electrochemical properties of the composites prepared at 0.05g were the best,that is,the 0.05GM composites had the best electrochemical performance,and the graphene and manganese dioxide produced a good synergistic effect.XRD and SEM analysis showed that the composite material was uniformly grown on the foamed nickel substrate.The film consisted of a layer of nanosheets and nanoflowers.The Mn and C elements on the film were formed by mapping the film.evenly distributed.The XRD diffraction peaks of the composites have distinct characteristic peaks of manganese dioxide and graphene.The electrochemical performance of the composite was tested.The electrochemical performance of 0.05GM composite was the best.At the scanning speed of 5mV/s,the specific capacity of the composite was 1476.51F/g,and it was charged and discharged at a current density of 1A/g.The specific capacity of the material is 1059.6F/g,and the equivalent series internal resistance is 0.875?.After 1000cycles of scanning at 100mV/s,the specific capacity retention of the material is 74.9%;at 10A/g current density,The material was subjected to 1000 charge and discharge tests,and the specific capacity retention rate of the material was 70.2%,indicating that the material has a high specific capacity and a certain cycle performance.2.When the graphene/manganese dioxide composite is prepared by reducing graphene oxide,potassium permanganate or SDS as raw materials,the composite material prepared by adding 0.4 g of potassium permanganate and 0.04 g of SDS is used.The electrochemical performance is the best,that is,the 0.4GM composite has the best electrochemical performance.XRD and SEM analysis showed that the composite material was uniformly grown on the foamed nickel substrate,and the film was formed by stacking a layer of nanosheets.The distribution of Mn and C on the film was performed by mapping the film.Evenly.There are obvious characteristic peaks of manganese dioxide and graphene in the XRD diffraction peak of the composite material.0.4GM electrochemical test showed that at a scanning speed of 5mV/s,the specific capacity of the composite was 874.45F/g,and it was charged and discharged at a current density of 1A/g.The specific capacity of the composite was 568.2F/g,equivalent.The internal resistance of the series is 1.03?;after 1000 cycles of scanning at 100 mV/s,the specific capacity retention of the material is 85.1%;at 10 A/g current density,the material is subjected to 1000 charge and discharge tests,the ratio of materials The capacity retention rate is 82.9%,indicating that the material has a high specific capacity and good cycle performance.