Preparation, Characterization And Electrochemical Properties Of Co₃O₄-based Anode Materials

Higher requirements for energy demand and utilization are required with the progress of society and living conditions.Lithium-ion batteries are the most popular electrochemical energy storage device for mankind currently.They have many advantages as environmental protection,high energy density,stable and safe performance,low self-discharge and no memory effect,etc.,which are widely used in many areas of our daily life.At present,the most commonly used anode material for lithium-ion batteries is graphite,but its energy density is low,which unable to keep up with the higher market demand.Co₃O₄ has a theoretical specific capacity,which has received extensive attention and research.In this research,Co₃O₄ based anode materials are served as the research object,Co₃O₄ and Co₃O₄/C composite materials are prepared by electrodeposition and subsequent calcination.The relationship between the structure of the material and the electrochemical performance is studied.The specific research content is as following:(1)Co₃O₄ precursors were grown on the titanium substrate directly by electrodeposition method.The conditions of electrodeposition like time,solution composition,solution temperature and concentration were adjusted and controlled to obtain Co₃O₄ precursor micro-nano arrays with different morphologies,which proved the feasibility of preparing Co₃O₄ material by electrodeposition.By comparative analysis the prepared Co₃O₄ precursor structure,the Co₃O₄ precursor array structure is optimal when the temperature is 90?,cobalt acetate tetrahydrate is the cobalt source.Follow-up research is carried out on these results.(2)Co₃O₄ nano-array were prepared by electrodeposition and subsequent calcination.Under the conditions of 1.0 V and 90?,different electrodeposition time(3h,6 h,12 h,24 h)was selected to prepare Co₃O₄ nano-array materials.With the increase of electrodeposition time,Co₃O₄ materials are varied from nanosheet arrays to nanowire arrays,and all of them are composed of nanoparticles with a diameter of5-20 nm.Among them,the Co₃O₄ nano-array prepared by the electrodeposition time of 3 h has the best performance.After 50 cycles at a current density of 100 mA·g^-1,the charge and discharge specific capacities are maintained at 1217 mAh·g^-1 and 1232mAh·g^-1,which exhibits good cycle stability.(3)Co₃O₄/CNTs composite was prepared by using multi-walled carbon nanotubes as a carbon source.The Co₃O₄/CNTs composite contains a small amount of multi-walled carbon nanotubes,which makes the overall electrochemical performance more excellent.When the current density is 400 mA·g^-1,the charging and discharging specific capacity is maintained at 762 mAh·g^-1 and 767mAh·g^-1,respectively.After charging and discharging at a high current density of12800 mAh·g^-1,when it returns to the initial current density of 100 mA·g^-1,the specific discharge capacity of the battery can quickly recover to 1107 mAh·g^-1,which is close to the battery's first discharge specific capacity of 1191 mAh·g^-1.(4)Co₃O₄/CDs composite was prepared by using carbon dots as a carbon source.The structure and morphology of the Co₃O₄/CDs composite electrode material has a huge change,a cross-linked network structure composed of nanoparticles was observed,which shows excellent electrochemical performance.When the current density is 400mA·g^-1,the charging and discharging specific capacity is still maintained at 1222mAh·g^-1 and 1228 mAh·g^-1.After charging and discharging at a high current density of 6400 mA·g^-1,the specific discharge capacity of the battery can quickly recover to1202 mAh·g^-1,when it returns to the initial current density of 100 mA·g^-1 which is close to the battery's first discharge specific capacity of 1296 mAh·g^-1.(5)Co₃O₄/r GO composite was prepared by using reduced graphene oxide as the carbon source.Compared with the pure Co₃O₄ electrode,a small amount of reduced graphene oxide is dispersed in the Co₃O₄ matrix.After 35 cycles at a current density of 100 mA·g^-1,the charge and discharge specific capacity still maintains 736mAh·g^-1 and 742 mAh·g^-1,which shows good cycle stability.