Synthesis Of Tin-based Chalcogenide Anode Material And Their Properties In Lithium And Sodium Storage

With increasing attention to the ever-increasing energy demand in the fields of electronics,renewable energy systems and electric vehicles,lithium-ion batteries(LIBs)are used worldwide due to their high energy density and stable cycle life.Based on this,the development of anode materials with high energy density and long cycle performance is particularly critical.Among them,tin chalcogenide(SnO₂,SnS₂,etc.)have become the most promising anode for lithium-ion batteries due to their rich reserves,eco-friendly,high theoretical specific capacity and safe working voltage(1.0 V vs.Li/Li⁺).However,the first irreversible conversion process in the charge and discharge process of the tin chalcogenide anode is likely to cause the initial coulomb efficiency to decrease.On the other hand,the alloying process is accompanied by a large volume change.As the cycle progresses,the mechanical integrity of the crystal grains is reduced,and then crushed and pulverized,which deteriorates the cycle stability of the tin chalcogenide anode.In addition,the rate performance of tin chalcogenide is severely limited by their low conductivity.Taking SnO₂ and SnS₂ as examples,the electrochemical performance of the material is improved by adopting strategies such as morphology design,phase control,and composite structure optimization.A composite material of tin sulfide/zinc sulfide/reduced graphene oxide with superior performance was successfully prepared by combining co-precipitation method,solvothermal method and appropriate calcination process.The material combines the synergistic effect of the heterostructure and the high conductivity of graphene,which improves the lithium and sodium storage performance of the material.The anode in lithium ion battery obtained a stable specific capacity of 510 m A h g^-1after 1000 cycles.As an anode in sodium-ion battery,it can still provide a reversible specific capacity of 357 m A h g^-1 after 100 cycles at a current density of 0.1 A g^-1.The honeycomb-like tin oxide and carbon composite material was prepared by one-step freeze-drying guided by sodium chloride and subsequent calcination,and the product was characterized and its electrochemical performance were tested.The results show that there are differences in morphology and structure of the products prepared by different raw materials(tin source or carbon source)or calcined at different temperatures.Among them,the composite material(H-SnO₂@3DC-550)obtained by using tin chloride pentahydrate and citric acid as raw materials and calcined at a specific temperature of 550°C shows the highest reversible capacity and the best cycle stability.It still has a reversible specific capacity of 797 m A h g^-1 after1000 cycles at a current density of 1 A g^-1,and a high rate performance of 382 m A h g^-1 at 5 A g^-1,and electrochemical performance significantly improved.The excellent electrochemical performance benefits from the honeycomb porous structure that provides buffer space and forms a highly conductive carbon network.Finally,the kinetic analysis and calculation of SnO₂@3DC-550 material are carried out.The calculation of the contribution ratio of pseudocapacitance confirms that the capacitance effect is beneficial to the electrochemical reaction of the electrode and enhances its electrochemical performance.This excellent structural design strategy and the simple,scalable and environmentally friendly synthesis method provide guidance for the manufacture of other metal oxide or sulfide anode materials.