Research On Capacitance Performance Of Graphene Composites Co-doped With Molybdenum Disulfide/nitrogen And Phosphorus

In order to solve the environmental pollution caused by traditional fossil fuels,it is extremely urgent to develop and utilize renewable energy sources and environmentally-friendly new energy storage devices.As a new type of energy storage device,supercapacitor is considered to be an ideal energy storage device because of its high power density,fast charge and discharge speed and long cycle life.Electrode materials are an important part of supercapacitors,and their structure will affect the electrochemical performance.Therefore,it is very meaningful to adjust the structure of the electrode materials to design electrode materials with outstanding electrochemical properties.Molybdenum disulfide?MoS₂?has attracted extensive attention in the field of energy storage because of its two-dimensional structure similar to graphene and large interlayer spacing.In this paper,the composite of MoS₂and nitrogen-phosphorus co-doped graphene?MoS₂/NPG?nanoflowers is prepared successfully by one-pot hydrothermal synthesis,and characterized by scanning electron microscopy?SEM?,transmission electron microscopy?TEM?and X-ray diffraction?XRD?,Raman analysis,X-ray photoelectron spectroscopy?XPS?.The electrochemical performance was tested by cyclic voltammetry?CV?,galvanostatic charge-discharge?GCD?,and electrochemical impedance spectroscopy?EIS?.The main contents of this article are as follows:?1?The pure MoS₂ and NPG were synthesized by one-pot hydrothermal method.They exhibited poor electrochemical performance because the two-dimensional layered material tends to agglomerate and accumulate.In the three-electrode system,the mass specific capacitance of pure MoS₂ reached 460 F g^-1 when the current density was 1 A g^-1.The mass specific capacitance of pure NPG reached 426 F g^-1 at 1?2?We prepared different proportions of molybdenum disulfide and graphene composites?MoS₂/RGO?by one-pot hydrothermal method.As the growth substrate of MoS₂,graphene not only effectively inhibited MoS₂ agglomeration,but also improved the conductivity of MoS₂.Experiments shown that the proportion of GO to molybdenum disulfide was most suitable when the addition amount was 0.06g,and the electrochemical performance was at its best.The specific capacitance could be as high as 525 F g^-1 when the current density was 1 A g^-1.?3?In order to study the effect of the doping amount of N and P on the material properties,different masses of?NH₄?₂HPO₄ were added as dopants for N and P,and MoS₂/NPG composites were synthesized.The experiment proved that the electrochemical performance was optimal when the addition amount of?NH₄?₂HPO₄was 0.3 g,and the mass specific capacitance of 588 F g^-1 could be achieved when the current density was 1 A g^-1.When the current density was 1 A g^-1,the mass specific capacitance of 102.5 F g^-1 could be achieved after assembly into a symmetrical supercapacitor.When the current density was 3 A g^-1,the capacitance retention rate still reached 91.67%after 5000 cycles.The symmetrical supercapacitor devices had an energy density of 24.34 Wh kg^-1 at a power density of 300 W kg^-1.