Preparation And Lithium Storage Properties Of NiCo₂O₄ And CoMn₂O₄ As Anode Materials For Lithium-ion Batteries

With the continuous development of the society,the lithium-ion batteries(LIBs)have been successfully entered various fields of our lives,ranging from all kinds of electronic products which we commonly used,such as smart phones,digital cameras,laptops to balance vehicles,electric bicycles and so on.However,the capacity of commercial lithium-ion batteries can no longer meet requirement.In order to adapt to the market demand,researchers mainly focused on increasing the battery capacity and power density,and reducing the production costs of the electrode material.Generally speaking,the anode and cathode materials can determine the capacity,rate performance and cycle performance of LIBs.Because of the higher theoretical specific capacity,transition metal oxides have become research hotspot,and it has a rich element content in the earth,which is convenient for industrial production.It has great potential to replace carbon materials as the new lithium-ion battery anode material.But due to the lower conductivity of these materials,and during the charge/discharge process,the volume expansion problem is very serious,which reduce the cycle performance and the rate performance of the battery.A lot of scientists have designed nano-hollow structure to solve the mentioned problems,it's an effective method to improve the performance of battery.Because of the special structure and size of the material are be designed,the diffusion way of lithium ions can be further shorten by the particular hollow nanostructure,the serious volume expansion problem can be alleviate effectively,so as to improve the electrochemical performance of LIBs.This paper will through a simple hard template method and a self template method to synthesize and design two novel mixed transition metal oxide product particles,to optimize and improve their rate performance and cycle performance as anode electrode.At the same time,X-ray diffraction,transmission electron microscopy,scanning electron microscopy and related electrochemical testing methods are used to analyze its morphological characteristics,phase composition and related electrochemical properties.The main works of this paper as follows:(1)Ag₂WO₄nanobrick material was synthesized by magnetic stirring method,as a hard template to adsorb Ni²⁺and Co²⁺in the condition of oil bath,by simple annealing in air atmosphere and a series of subsequent etching treatments,hollow Ni Co₂O₄nanobrick material was be obtained.During the charge/discharge process,the hollow structure can alleviate the volume expansion problem of Ni Co₂O₄anode material.More active sites can be exposed by the wrinkles of the material,it provide more opportunities to the active material and the electrolyte to contact,due to the existence of synergistic,the material's mass specific capacity and cycle stability have been fastly improved.In electrochemical tests,at 2 A·g^-1,reversible capacity is 412m Ah·g^-1,at 400 m A·g^-1after 450 cycles,specific capacity remains 854 m Ah·g^-1,apperantly,it showing excellent rate performance and cycle performance.(2)Spherical Co-Mn precursor spheres were synthesized by solvothermal method,as precursor annealing in air atmosphere to obtain Co Mn₂O₄nanospheres with some wrinkles on the surface.Specific capacity and cycle stability were be improved by active sites and synergistic effects of two metals.In electrochemical tests,when current density is 200 m A·g^-1,after 50 cycles,specific capacity of the LIBs can reach 694 m Ah·g^-1,at 600 m A·g^-1,After 50 cycles,the reversible capacity still remained 377 m Ah·g^-1,in a word,the material which we synthesized shows nicer rate performance and cycle performance.