Exploitation Of Key Materials And Research Of Related Mechanism For Rechargeable Magnesium Batteries

The demand for safety,sustainability and high energy density energy storage technology has stimulated people's research interest in rechargeable magnesium(Mg)batteries(high volumetric capacity,large crust abundance).However,due to the lack of practical key components,the realization of its application potential is still hindered for a long time.To become a strong competitor in the construction of energy-intensive systems,the challenges that magnesium batteries have to overcome in the long term,including Lack of high-performance Mg-storage cathode materials and outstanding compatibility electrolyte system.Herein,copper sulfide(Cu S),a conversion reaction cathode,has effectively avoided the difficult diffusion kinetics of traditional intercalation cathodes.In addition,an artificial interface layer is constructed on the surface of the magnesium metal anode to expand the range of electrolyte options.Specifically,the main research work of this paper is as follows:Copper sulfide composited with graphene as an improved cathode for re-chargeable magnesium batteries:A cathode material composed of Cu S nanorods and reduced graphene oxide(Cu S@r GO)was prepared by a one-pot method.Through the characteristic structure and electrochemical performance of layered graphene,nano-copper sulfide with high electrochemical reaction kinetics is dispersed and fixed to ensure its high activity and cycle stability in the electrochemical redox reaction process.Thanks to this special composite structure,the Cu S@r GO cathode exhibits high reversible specific capacity and excellent rate performance.In addition,in situ X-ray powder diffraction(XRD),transmission electron microscopy(TEM)and X-ray photoelectron spectroscopy(XPS)were used to thoroughly explore the magnesium storage mechanism of Cu S@r GO cathodes,and further revealed the key factor in the degradation of its Mg-storage performance.A bismuth-based protective layer for dendrite-free magnesium metal anodes in noncorrosive electrolytes:A facile,safe and effective approach to construct a metal–alloy hybrid artificial interphase layer on the Mg metal surface to improve the compatibility of Mg metal anode with simple Mg salt(Mg(TFSI)₂)based electrolyte remarkably.A simple chemical reaction occurs between Mg metal and Bi Cl₃ to form the protective layer on the Mg metal surface,which composed of Mg²⁺-conducting Bi-based compounds(e.g.Mg₂Bi₃,Bi),and electron insulating Mg Cl₂.The artificial Bi-based protective layer effectively blocks the side reaction of TFSI^–anion towards Mg metal anode,and meanwhile perfectly suppresses the uneven growth behavior of Mg deposits during electrodeposition process in the Mg(TFSI)₂/DME electrolyte.More importantly,the protected Mg metal anodes not only exhibit superior cycling stability and rate capability when coupling with the Cu_2-xS cathode,but also display improved charge-discharge reversibility and cycling stabilities in Mg–O₂ cells.These results demonstrate the great potential of the artificial Bi-based protective layer as an effective strategy for the rational design of high-capacity Mg batteries.