Study On Preparation And Properties Of Zinc Selenide Electrode Materials

In recent years,people have invented a variety of rechargeable battery systems to meet the growing demand of various energy applications,such as grid storage,hybrid vehicles,portable electronic equipment,etc.Among them,lithium-ion batteries（LIBs）and sodium ion batteries（SIBs）have attracted much attention due to their high energy density,long cycle life and environmental friendliness.Zinc selenide has excellent chemical,optical and photoelectric conversion effects,and is widely used in chemical energy storage,lasers,solar cells,dielectric materials and other fields.In this dissertation,the hollow Zinc selenide（ZnSe）microspheres were prepared by the combination of solvothermal and hydrothermal methods,and were used as lithium anode materials and sodium anode materials to analyze their electrochemical properties.Then,the hollow ZnSe microspheres were modified by graphene oxide,and the electrochemical properties and advantages of the modified ZnSe-r GO composite membrane as lithium anode materials and sodium anode materials were analyzed.The main work of this dissertation is as follows:Firstly,the process parameters of ZnSe preparation were optimized by solvothermal method with reaction temperature and glycol content as single factors.The results show that[Se²⁺]/[Zn²⁺]is 1:1,the reaction time is 10h,the reaction temperature is160℃,and the amount of glycol is 17ml,the hollow ZnSe microspheres were prepared.The advantages and disadvantages of hollow ZnSe microsphere and solid microsphere in the electrochemical reaction were analyzed theoretically.And the reason of hollow ZnSe microsphere are used as anode material for lithium and sodium batteries was stated.Then,the hollow ZnSe microsphere were fabricated into lithium and sodium electrodes respectively by the electrode coating process.In this dissertation,the morphology,structure and electrochemical properties of the hollow ZnSe microsphere were analyzed.The results show that the stable specific capacity of hollow ZnSe is36.4 m Ahg^-1higher than that of sodium,but the stable specific capacity fluctuates greatly,and the cycle stability of hollow ZnSe microsphere is more stable than that of lithium.Finally,the hollow ZnSe microspheres were combined with graphene oxide by suction filtration to obtain the flexible electrode ZnSe-r GO composite membrane.Through the electrochemical performance test,compared with the hollow ZnSe microsphere as the negative material of lithium battery,the charge discharge process of ZnSe-r GO composite membrane is more stable,and the specific capacity of composite membrane is increased to 306.2 m Ahg^-1(the unstable specific capacity of hollow ZnSe microsphere is 261.7 m Ahg^-1).The results show that graphene oxide can improve the cycling stability of anode materials.However,the specific capacity of ZnSe-r GO composite membrane increased from 215.3 m Ahg^-1to 383.67 m Ahg^-1,compared with the hollow ZnSe microsphere as the negative electrode material of sodium.The results show that graphene improves the specific capacity of the battery to a great extent when the battery cycle is relatively stable.Based on the structural characteristics of graphene oxide and the electrochemical advantages of hollow microspheres,a new type of film-forming method was adopted to prepare a crisscross space network composite film,the prepared negative materials greatly improved the specific capacity and cycle stability of lithium and sodium batteries.