Preparation Of Manganese Selenide And Carbon Coated Manganese Selenide And Their Applications Of Supercapacitors

Manganese selenide is a typical transition metal selenide with three crystal structures:α-MnSe（rock salt structure）,β-MnSe（wurtzite structure）andγ-MnSe（zinc blende structure）.Theαphase is the most thermodynamically stable phase.As an anti-ferromagnetic semiconductor material,manganese selenide has high electrical conductivity in theory.It has attracted wide attention in electromagnetism,optoelectronics and other fields.It is mainly used in electrode materials of lithium ion/sodium ion battery,capacitor electrode materials,thermoelectric materials,diluted magnetic semiconductor materials and solar cells.At present,the research on manganese selenide is mainly focused on the magnetic and electrode materials,and the research on its application in supercapacitor is very few.Further theoretical and experimental research is needed.In this thesis,the cubic phaseα-MnSe nanospheres and carbon-coated MnSe nanomaterials were prepared by DC arc plasma method.The phase and morphology were characterized,and the synthesized materials were used as supercapacitors.Electrode materials,the electrochemical performance of electrode materials was studied,and the influence of carbon coating on its electrochemical performance was analyzed and compared.The specific work content is as follows:（1）Using manganese powder and selenium powder as raw materials,using DC arc plasma method,MnSe nanomaterials were synthesized by adjusting the current and pressure parameters,and the phase composition and microscopic morphology of the synthesized materials were characterized and analyzed under the optimal conditions.The MnSe nanomaterial synthesized under the optimal conditions was used as the electrode material of the supercapacitor.After electrochemical testing,it has a specific capacitance of 166.2 Fg^-1 when the current density is 1 Ag^-1,which indicates that the MnSe nanomaterials have the value of being used as electrode materials for supercapacitors.（2）Using manganese powder,selenium powder and carbon powder as raw materials,the carbon-coated MnSe nanomaterials were synthesized by the DC arc plasma method,the current value was 140 A and the argon pressure was 60 k Pa,and the phase composition and microscopic morphology were characterized.The carbon-coated MnSe nanomaterial is used as the electrode material of the supercapacitor.After electrochemical testing,it has a specific capacitance of 452.4 Fg^-1 when the current density is 1 Ag^-1,and the capacity retention rate of MnSe nanomaterials is 83.1%when the current density is 5 Ag^-1 for 5000 cycles.Compared with MnSe nanospheres,the capacity of carbon-coated MnSe nanomaterials has been significantly improved.