Research On Preparation And Electrochemical Properties Of Carbon-coated Nano-aluminum Fluoride

With consumer electronics becoming ever thinner and lighter and the need for electric vehicles to compete with existing internal combustion engines,batteries need to be constantly improved.At present,the research on the new generation of lithium ion batteries with high specific energy has entered the white-hot stage.Due to its high theoretical specific capacity(957 mAh·g^-1),abundant reserves and stable properties,as well as its advantages of non-pollution to the environment,aluminum fluoride can be used as a new cathode material for lithium ion batteries for research.However,due to the poor conductivity of aluminum fluoride and poor electrochemical performance,how to improve its conductivity and electrochemical performance is a key issue to be solved.Therefore,through some processing and modification methods,improving its conductivity and electrochemical performance is the main research content of this paper.The work of this paper combines the material processing technology and lithium ion battery two fields,which have obvious interdisciplinary characteristics.The research content mainly includes the following two aspects:?1?Construction of high energy ball mill system,preparation of nano aluminum fluoride and electrochemical properties.In order to explore the influence of further refinement of particle size to nano-scale on the electrochemical properties of aluminum fluoride materials,a high-energy ball mill system was built to prepare nano-aluminum fluoride.The purchased commercial aluminum fluoride was used as the raw material to refine the material particles to the vicinity of 100nm by high-energy ball grinding.The characterization and electrochemical properties of aluminum fluoride after ball milling were analyzed,and preparations were made for further improvement of its electrochemical properties by surface modification of carbon coating.The results show that the electrochemical properties of aluminum fluoride are greatly improved compared with those of the purchased raw material aluminum fluoride due to the increase of electroactive surface area and the smaller path of electrons and ions through which aluminum fluoride is nano-sized.?2?Construction of carbon clad system,preparation of carbon clad aluminum fluoride and electrochemical properties.In order to explore the influence of surface modification by carbon cladding on the electrochemical properties of aluminum fluoride materials,a carbon cladding system was established to prepare carbon cladding aluminum fluoride materials with purchased commercial aluminum fluoride and aluminum fluoride after ball milling as raw materials.The carbon-coated aluminum fluoride was characterized and its electrochemical properties were analyzed.The results show that the electrochemical properties of aluminum fluoride coated with carbon have been improved,especially that of aluminum fluoride coated with carbon after ball milling to nanocrystallization.After carbon coating,the conductivity of aluminum fluoride was enhanced and the concentration polarization was further decreased.Moreover,the carbon layer prevents direct contact between aluminum fluoride and electrolyte,thus achieving a higher capacity at a specific current density.