Preparation And Application Of Multilayer Graphene Surface SnO₂ And TiO₂ Nanocomposites

The transition metal oxide SnO₂ and TiO₂ nanomaterials have good application value in the electrode materials of lithium ion batteries and lithium sulfur batteries.Compounding with graphene can improve the conductivity of such metal oxide materials and reduce the agglomeration of nanoparticles,which can optimize the microstructure of the material and further improve the performance of the material.Different from the traditional preparation of composite materials using graphene oxide and metal salts and other raw materials,this paper uses multi-layer graphene prepared by mechanical peeling as a carbon-based material,exploring the use of corresponding metal powders as raw materials to prepare nanocomposites,and exploring Performance of a composite material as electrode material for lithium ion batteries and lithium sulfur batteries.The main research contents of this paper are as follows:?1?Using tin powder as the tin source,a nano-tin dioxide/multi-layer graphene composite material was prepared by a one-step water bath method.The effects of the addition of tin powder and temperature changes on the morphology and structure of the composite material were studied,and the electrochemical performance of the composite material as the anode material for lithium ion batteries was tested.The experimental results show that the reaction at 80?for 5 hours,the best performance of adding 10mg tin powder,100 cycles at 100m A g^-1 current density,the reversible specific capacity remains 750m Ah g^-1.The nano-tin dioxide/multi-layer graphene composite material and sublimation sulfur were compounded by the molten sulfur injection method to obtain the sulfur/nano-tin dioxide/multi-layer graphene composite material,and the electrochemical performance was tested.The results show that the composite material has a good sulfur shuttle suppression effect.The composite material can maintain a reversible specific capacity of 270m Ah g^-1 after 980 cycles under 2C cycling conditions.?2?Titanium dioxide nanorods/multi-layer graphene composite materials were prepared by one-step water bath method using titanium powder as the titanium source.The effects of different amounts of hydrochloric acid and reaction time on the microstructure of the composite material were studied.The electrochemical performance of the composite material as the anode material for lithium ion batteries was tested.The experimental results show that the best TiO₂ nanorods/multilayer graphene composites are cycled 100 times at a current density of 100m A g^-1,and the reversible specific capacity is maintained at 644m Ah g^-1.The prepared titanium dioxide nanorod/multi-layer graphene composite material and sublimation sulfur were compounded to obtain sulfur/nano-titanium dioxide/multi-layer graphene composite material,and their electrochemical properties were tested.The research results show that the composite material has a specific capacity of 200m Ah g^-1 after 100 cycles under 2C cycling conditions,and its sulfur-fixing effect is analyzed.Based on the research in this thesis,a method was used to prepare nano-tin oxide and titanium oxide in situ on the surface of carbon materials using tin powder and titanium powder as raw materials.The preliminary application of this kind of composite materials in lithium ion batteries and lithium sulfur batteries was studied.