| Magnesium ion batteries have become a potential energy storage device in recent years due to their characteristics of environmental friendliness,abundant reserves,low cost,safety and reliability.However,Mg2+has a large radius and serious polarization,which makes it difficult to insert and extract,resulting in poor cycle stability of the cathode materials.Therefore,the cathode materials of magnesium ion batteries have become a hot research topic.In this paper,nanostructured copper selenide,cuprous selenide,and doped graphene oxide composite cathode materials for magnesium ion battery were mainly synthesized by microwave method,and related electrochemical performances were studied.?1?Using Na2Se O3and Cu?CH3COO?2·H2O as raw materials,deionized water as a solvent,hydrazine hydrate as a reducing agent,and heating at 105°C for 15 min,Cu Se powders with a particle size of about 50 nm was synthesized.The coin magnesium battery was assembled using Cu Se powder as cathode electrode material,metal Mg as anode electrode material,and 0.25 M Mg?Al Cl2Et Bu?2/THF as electrolyte.In the voltage range of 0.2-2 V,the first discharge capacity of magnesium ion battery at a current density of 50 m A g-1was 154.1 m A h g-1,and the highest can reach 223.1 m A h g-1.After 60 cycles,the specific capacity of the magnesium battery was stable at 200 m A h g-1.At the same time,at a current density of 100 m A g-1,the reversible capacity of battery was maintained at 107.7 m A h g-1after 150 cycles.?2?The nano-Cu Se doped GO composite was synthesized by microwave method using Na2Se O3,Cu?CH3COO?2·H2O and graphene oxide?GO?as raw materials,deionized water as solvent,and hydrazine hydrate as reducing agent.The results of electrochemical performance show that in the voltage range of 0-2 V,the reversible capacity of magnesium battery can reach the maximum value of 230.4m A h g-1at a current density of 100 m A g-1when it is mixed with 2 m L of GO suspension;At a current density of 200 m A g-1,the reversible capacity of the composite material doped with 2 m L GO suspension was maintained at 118.1 m A h g-1after 160 cycles,and the composite materials doped with 10 m L GO suspension was maintained 83.7 m A h g-1for 190 cycles.?3?The Cu2-xS precursor was first prepared by microwave method using Cu Cl2·H2O and CH4N2S as raw materials,according to the molar ratio of 6:23,ethylene glycol as the solvent,hydrazine hydrate as the reducing agent.Then the precursor and Se powder were used as raw materials,according to the molar ratio of1:5 and 1:2,heated to 500?under nitrogen atmosphere,holding for 2 h,synthesized a thickness of 6.0 nm,length and width of 3?m flower-like structure Cu2Se and Cu1.8Se nanosheets.The electrochemical performance of the above two kinds of nanosheets as cathode materials for magnesium batteries was tested.At a current density of 50 m A g-1,the reversible capacity of the Cu2Se electrode after 20cycles was 238.3 m A h g-1,which was higher than that of Cu1.8Se reversible capacity(197 m A h g-1).At a current density of 100 m A g-1,the first and 70 cycles specific discharge capacities of Cu2Se nanosheets were 240.7 m A h g-1and 190 m A h g-1,which were higher than Cu1.8Se nanosheets(181.1 m A h g-1and 136 m A h g-1).The above results show that the electrochemical performance of Cu2Se nanosheets was better than that of Cu1.8Se nanosheets.?4?The graphene-like layered Cu2Se nanosheets with a thickness of 10.0 nm and the length and width of about 200 nm were prepared by hydrothermal method using Cu?NO3?2·H2O and Na2Se O3as raw materials with a molar ratio of 1:1,the ethylene glycol and deionized water as sovlents at 140°C for 6 h and a pressure of50 MPa.When the nanosheets as the cathode electrode of magnesium ion battery and metallic Mg as the negative electrode,the specific capacity of the electrode after20 cycles at 50 m A g-1was 149.1 m A h g-1;At a current density of 100 m A g-1,the specific discharge capacity of the electrode was stable at 200 m A h g-1.After 70cycles,the reversible capacity can retained 95.2 m A h g-1.This result indicates that its electrochemical performance was not as good as the flower-shaped Cu2Se nanosheets. |
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