Facile Synthesis Of CuSe-based Nanomaterials And Their Electrochemical Properties

As an energy storage device, lithium ion battery has been widely used in mobile phones and other portable devices, because of their high specific energy, long cycle life, environment friendly, and portability. Now, they are being intensively pursued for transportation applications in electric vehicles（EV）, as well as seriously considered for stationary storage. In order to meet the new requirements, it is a hotspot of scientific research that developing the lithium ion battery anode materials with higher capacity, higher power and longer life. The fluid-like Cu in copper chalcogenide can provide high ion conductivity and free vacancies for Li migration, which make it a potential candidate for lithium ion battery technology. Thus this research chose Cu Se-based materials as the object and tried to obtain various structure of Cu Se by microwave assisted method and ternary alloyed Cu Se S nanocrystals by solvthermal synthesis. The microscopic morphology and phase composition were characterized by XRD, XPS, SEM, and TEM, while their electrochemical performances were measured. Furthermore, the relationship between battery performance and structure were discussed.Cu_2-xSe naonorods were synthesized with formamide as solvent by using microwave assisted method. The amounts of sodium tartrate and alkali can affect the size and uniformity of the nanorods. The Cu₂-xSe naonorods electrode could effectively enhance electrochemical performance, because of one-dimensional nanostructures. Stable capacity of 210 m Ah g-1 was observed over 100 cycles at the current density of 50 m A g-1.Cu_2-xSe nanosheets were prepared using ethylene glycol as solvent, and increasing the amounts of sodium tatrate results in the distribution of particle on the surface of nanosheets. This kind of hierarchical structure is conducive to improving electrochemical performance of the products. It is shown the initial capacity of 400 m Ah g-1 and the reversible capacity of 330 m Ah g-1 after 30 cycles.Ternary alloyed Cu Se₁-xSx of hexagonal phase was synthesized by one step solvothermal method, which was reported for the first time. The study shows that thickness and size of the hexagonal nanosheets are associated with ratio of solvents. The nanosheets can shorten lithium diffusion distances, and provide the reversible capacity of up 500 m Ah g-1, and maintain the capacity of more 300 m Ah g-1 over 60 cycles. Impedance tests show that the charge transfer resistance of the electrode interface gradually decreased throughout the cycles.