Preparation And Electronchemical Properties Of Co-based Ternary Transition Metal Oxides For Lithium Ion Batteries Anode Materials

Lithium ion batteries have been widely used in various fields due to their high energy density,low cost and long cycle life.But the commonly used graphite anode material has a low theoretical capacity,which could not satisfy the increasing demands of people.Therefore,it is urgent to find new anode materials with high charge/discharge capacity and good cycle performance.Compared with graphite anode materials,the ternary transition metal oxides have high theoretical capacity and good conductivity,which have been widely studied.The purpose of this paper was to improve the electrochemical performance of lithium ion batteries.Using ternary transition metal oxides as the center,the electrochemical performance of the materials were improved by the methods of building hollow structure and composite.The main contents include the following three sections:Firstly,porous hollow CuCo₂O₄ nanospheres and hollow MgCo₂O₄ nanospheres were successfully synthesized by one step hydrothermal method.The effect of hollow structure on the electrochemical performance of lithium ion batteries was studied.Compared with solid CuCo₂O₄ nanospheres,porous hollow CuCo₂O₄ nanospheres exhibit excellent electrochemical performance,at a current density of 0.1 A g^-1,the reversible capacity of the porous hollow CuCo₂O₄ nanospheres after 150 cycles remained at 930 mAh g^-1,the reversible capacity of solid CuCo₂O₄ nanospheres attenuation to 430 mAh g^-1 after only 70 cycles.This results show that construction of hollow structure would enhance the surface area,which helps to provide large numbers of active sites for lithium storage and can enlarge the contact area of the electrolyte and electrode,therefore it would be improve the lithium storage performance of electrode.Secondly,the CuCo₂O₄/rGO composites were synthesized by hydrothermal method.Compared with pure CuCo₂O₄,graphene composites exhibit good cycling performance and rate performance.At a current density of 0.5 A g'1,the capacity of CuCo₂O₄/rGO composite after 200 cycles can be maintained at 900 mAh g^-1,the excellent electrochemical performance was due to introduced graphene,which can alleviate the volume expansion and also can overcome the agglomeration of nanoparticles.Thirdly,the hollow HC@NiCo₂O₄ microspheres were successfully synthesized by hydrothermal method.Through thermogravimetric analysis,the carbon content of the synthesized composites was 23.1%,the unique structure makes it as anode materials for lithium ion batteries exhibit excellent electrochemical performance,after 100 cycles the discharge capacity remained at 810 mAh g^-1(0.5 A g^-1).The material presented a hollow nano-flower structure,which promote the contact of electrode and electrolyte during the charge and discharge processes,can form a larger solid contact surface,it can shorten the transmission path of electrons and ions,so that improve its electrochemical performance.