Preparation And Performance Study Of Transition Metal Chalcogenide Composites

Supercapacitor has the advantages of common capacitor and battery,supercapacitor has higher power density and superior cycle life,and it has become a research upsurge in recent years.The preparation of electrode materials with good electrochemical properties is the key to all the research of supercapacitor.Carbon-based materials,metal compounds,conductive polymers,and various composite materials have obtained extensive research in academia at present.In the past few decades,transition metal chalcogenide have been widely explored by researchers due to their high specific capacitance.As a pseudocapacitor material,transition metal selenides have higher specific capacitance,high crust content,low price,and simple preparation process.However,the exploration of supercapacitor for transition metal selenides remains to be further studied.Therefore,in this paper,electrochemical excellent electrode materials were prepared by combining transition metal selenides with carbon-based materials and combining two kinds of transition metal selenides.Some electrode materials with superior electrochemical performance were obtained by rationally applying the synergistic effect between two materials.The following studies were specifically carried out:1.Nano-flowered MoSe₂ and nanoparticulate CoSe₂ were synthesized by hydrothermal method using ammonium molybdate,cobalt acetate and selenium dioxide as basic materials.The specific capacitance of the MoSe₂ reaches 93 F/g at a scan rate of 5 mV/s,17 F/g at a current density of 0.5 A/g.The specific capacitance of the CoSe₂reaches 165 F/g at a scan rate of 5 mV/s,99 F/g at a current density of 0.5 A/g,The specific capacitance of CoSe₂ is better than that of MoSe₂.2.Based on the preparation of CoSe₂,CoSe₂/rGO composites and CoSe₂/CNTs composites were synthesized by hydrothermal method.The optimum ratio of graphene oxide and carbon nanotubes were investigated by changing the amount of carbon-based material added during the reaction:When the blending ratio of rGO is 5 wt%,the CoSe₂/rGO composite has the best supercapacitor behavior.The specific capacitance of the CoSe₂/rGO reaches 399 F/g at a scan rate of 5 mV/s,219 F/g at a current density of0.5 A/g.When the blending ratio of CNTs is 5 wt%,the CoSe₂/CNTs composite has the best supercapacitor behavior.The specific capacitance of the CoSe₂/CNTs reaches 315F/g at a scan rate of 5 mV/s,169 F/g at a current density of 0.5 A/g.3.Three binary transition metal selenide?MoSe₂/CoSe₂?composites were prepared by hydrothermal method.The three different binary metal transition selenide composites were prepared by adding different molar ratios of raw materials during the reaction.The binary transition metal selenide MCS₁₁ consists of hexagonal MoSe₂ and orthorhombic CoSe₂ and cubic CoSe₂.The structures of the three binary transition metal selenides are nanosheets attached to microtubules.The specific capacitance of MCS₁₁ is better than that of MCS₃₁ and MCS₁₃,the specific capacitance of the MCS₁₁reaches 349 F/g at a scan rate of 5 mV/s,168 F/g at a current density of 0.5 A/g.