Preparation And Study Of Electrode Materials And Dual-salt Electroyltes Enabled Rechargeable Mg Batteries

Magnesium resources in our country is very rich,reserves the highest in the world,with such unique advantages of the development of rechargeable magnesium ion batteries.The standard electrode potential of magnesium metal electrode is-2.38 V?vs.SHE?,and the theoretical specific capacity is up to 2205m Ah/g and 3832 m Ah/cm³.Although it is difficult to compare the power supply of small equipment with that of lithium battery,its low price,environment friendliness and potential feasibility of supplying power for large equipment.Therefore,rechargeable magnesium ion battery is a kind of chemical energy with good application prospects.Over the past few decades,researchers have been working on the development of rechargeable magnesium ion batteries,however in practical applications,achieving high-performance rechargeable magnesium batteries still faces many challenges:?1?It is difficult that magnesium ions inserted into the cathode material,such as traditional lithium cathode material,resulting in less choice of cathode material;?2?magnesium metal surface will generate a passivation layer that does not conduct ions in most conventional electrolytes.Therefor e,the study of magnesium batteries is still in a preliminary stage,and its charge and discharge efficiency and capacity have not reached commercial standards.Therefore,we chose to study transition metal sulfides in order to improve the rechargeable magnesium batteries with high discharge specific capacity for magnesium ions in the cathode material.In order to avoid the formation of passivation layer,we use magnesium alloys instead of magnesium metal.And the suitable cathode material improves the energy density of the battery.This article focuses on the following research:1.In order to find a suitable magnesium battery cathode material and increase the magnesium ion insertion rate,we use molybdenum disulfide.Such cathode material is a composite material composed of nitrogen-doped carbon nanofibers coated with molybdenum disulfide nanosheets prepared by one-step hydrothermal method.Then,the above-mentioned composite material is compounded with a dual-salt electrolyte to increase the insertion/de-insertion efficiency.The multi-layer conductive network architecture constructed by the composite nanofiber structure enhances the dynamics and stability of the electrode.The synergistic effect exhibited by this composite promotes a good Coulombic efficiency?99%on average?for rechargeable magnesium batteries,a high specific capacity?350 m Ah/g for the initial cycle?,and stability cycles(120After the charge-discharge cycles,91%capacity was maintained and excellent rate performance was achieved?110 m Ah/g at 1 A/g?.2.In order to solve the problem of the passivation layer produced on the surface of magnesium metal and the electrolyte corrosive the battery material at high voltage,we further investigated the use of Mg₃Bi₂ alloy as a aelectrode anode material instead of magnesium metal,so that the rechargeable magnesium ion battery can be used in a non-corrosive conventional electrolyteand stable cycling.The synthesis of Mg₃Bi₂ alloy use a high-temperature alloying reaction.Such method has the advantages of being able to synthesize in massive quantities and without the production of other toxic by-products.It matches the high-voltage Prussian Blue cathode material at a current density of 0.1 A/g.Shows extremely high reversible specific capacity?3 60 m Ah/g?with excellent stability?capacity retention after 90 cycles of 90.7%?and high Coulombic Efficiency?average of 98%?...