Synthesis Of Transition Metal Oxide Anode Materials And Their Lithium/Sodium Storage Performance

Lithium ion battery have been used in electronic products and electric vehicles because of their environmental protection,high energy density and long cycle life.However,the lower theoretical capacity of commercial graphite anodes seriously restrict its further development.And sodium ion battery are considered to be the most probably candidates to substitute lithium ion battery owing to its enrichment Na resources,low cost,energy storage mechanism similar to lithium ion battery,as well as similar physical and chemical properties between lithium and sodium.Synthesizing a lithium/sodium anode material with a unique morphology and structure is an effective method to improve its electrochemical performance.TMO have the advantages of high electrochemical activity and high theoretical specific capacity,so they are considered as promising anode materials and have received extensive attention from researchers.In this paper,high-performance electrode materials such as NiFe₂O₄,Zn Fe₂O₄,Ni_0.75Zn_0.25Fe₂O₄ with different topography were constructed by biological template,hydrothermal,and precipitation methods,and characterized and tested the prepared materials.The major research details are as follows:(1)Hierarchical porous NiFe₂O₄,Zn Fe₂O₄,Zn Mn₂O₄ and Ni O nanosheets were prepared using bagasse as a template.The prepared nanosheets are composed of 20-50 nm fine particles and have a thickness of 150-200 nm.The prepared transition metal oxide nanosheets exhibit good electrochemical performance.Taking hierarchical porous NiFe₂O₄nanosheets as an example,when it is used as a lithium battery anode electrode,at 200 and500 m A g^-1,the first cycle charge/discharge specific capacity is 1295.5/1677.4 m Ah g^-1 and1061.7/1484.9 m Ah g^-1,respectively.And after 300 cycles,the discharge specific capacity is 1229.1 and 989.6 m Ah g^-1,respectively.When used as a sodium battery negative electrode,it can display a specific capacity of 162.3 m Ah g^-1 after 700 cycles at 200 m A g^-1.The good electrochemical performance of hierarchical porous transition metal nanosheets can be attributed to its unique structure.Compared with the reported method for preparing hierarchical porous transition metal nanosheets,the method has the advantages of low cost,environmental protection,and easy preparation.(2)Hollow Ni_0.75Zn_0.25Fe₂O₄ nanospheres were prepared by a uncomplicated one-step hydrothermal method.The hollow structure was characterized by SEM and TEM,and the outcomes displayed that the product has well dispersibility,and the average diameter is approximately 220 nm,as well as the hollow wall thickness is about 30-50 nm.When used as the anode electrode of lithium ion battery,under 200 m A g^-1,the first cycle charge/discharge specific capacity is 1334.5/1763.1 m Ah g^-1 respectively,the coulombic efficiency is 75.7%,and the specific capacity is 1321.3 m Ah g^-1 after 120 cycles;When used as a sodium battery negative electrode,it can display a specific capacity of 178.5 and125.7 m Ah g^-1 after 800 cycles at 200 and 500 m A g^-1,respectively.Compared with the second cycle,the retention rates were 91.6%and 89.3%,respectively.The excellent electrochemical performance of Ni_0.75Zn_0.25Fe₂O₄ anode can be attributed to its unique hollow nanosphere structure.(3)In order to maximize cost savings and obtain electrode materials with relatively excellent performance,ultra-thin ZnO nanosheets were obtained through a simple precipitation method.XRD,SEM,TEM and other characterizations are used to analyse the structure and morphology of the synthesized materials.The outcomes display that the obtained ZnO has an ultra-thin sheet structure with a uniform and smooth surface.The data shows that when used as the negative electrode of a lithium battery,the first cycle charge/discharge specific capacity at a current density of 300 m A g^-1 is 541.4/1381 m Ah g^-1,respectively,and after 100 cycles,the discharge specific capacity is 403.6 m Ah g^-1.When used as a sodium battery negative electrode,it can display a specific capacity of115.8 m Ah g^-1 after 280 cycles at 100 m A g^-1.which indicating that the material has excellent cycling performance.