Preparation Of Cobalt Compounds/Carbon Composites As Anode Materials For Lithium Ion Batteries

As a kind of energy storage and conversion device,secondary lithium ion batteries have been widely used in our daily lives.The lithium-ion battery system become more and more maturity under long-term development and continuous improvement.Battery equipment need provide higher energy density and better safety performance to apply in wider field.At present,most of the commercial anode materials are graphite,which have low theoretical capacity?372 mAh/g?and energy density and exist security risks.Therefore,exploring other anode materials with high capacity and good safety performance is extremely urgent.Transition metal compounds are candidates for replacing graphite due to their high theoretical specific capacity,good safety performance and abundant.In this paper,transition metal sulfides and oxides including CoS/C,Co₃O₄/C,CoMoO₄/C have been made through simple method and used as anode materials of lithium ion batteries.The physical characterizations were tested by XRD,SEM,TEM,Raman,N₂ adsorption and desorption.And the electrochemical performances were also evaluated.The detailed contents were presented as follows:?1?CoS hollow spheres were synthesized through one-step solvothermal method.CoS/C was prepared by grinding CoS and glucose together,followed by calcination.The experimental results showed that hollow structures can relieve the volume change during the charge and discharge process.The electrochemical performance can be improved by carbon coating.But the material still possess poor rate performance when testing under high current density.?2?Porous Co₃O₄/C were prepared via grinding and calcination,following a series of physical properties and electrochemical behavior were conducted.The porous structures can shorten the diffusion path of lithium ions and relieve the volume changeduring the charge and discharge process,which maintaining the structure of the materials stable.Adding carbon can improve the conductivity of the material.Electrochemical results show that Co₃O₄/C has superior cycle and rate performance compared to Co₃O₄.?3?CoMoO₄ nanorods were synthesized through reflux method at low-temperature and then carbon coating it to obtain CoMoO₄/C.Simultaneously,the electrochemical performance tests exhibit the CoMoO₄/C display excellent properties of cycle and rate performance.The conductivity can be improved by decorating carbon to CoMoO₄nanorods.To some extent,the carbon coating can retain the structure integrity during the cyclic process.