The Synthesis And Electrochemical Properties Of Transition Metal Compounds/carbon Nanofibers Composites

Due to its high energy density,good performance,long service life,environmental protection and no memory effect,Lithium ion batteries have become the focus of the new energy materials.Nowadays,Lithium ion batteries are widely used in mobile phones,laptops and other electronic products industry.Besides,they also used in electric vehicles and hybrid electric vehicle.However,With the growing demand for lithium ion batteries,developing a new type of lithium ion battery with higher energy density,better cycle performance and longer service life has become one of the most valuable research in the field of new energy.As the core material of the lithium ion battery,the anode material determines the lithium storage capacity of lithium ion battery.At present,carbon materials are usually used as anode materials because of its excellent cycle stability.However,the theoretical capacity of carbon materials is low,only 372 mAh g^-1,its lower lithium storage performance can not meet the needs of mankind.In recent ten years,transition metal compounds have been widely concerned by researchers at home and abroad because of their high theoretical capacity.However,these materials affected by by solid electrolyte interface and volume effect,showed poor cycle stability.In this paper,based on previous experience,mixing the carbon nanofibers and transition metal compounds was firstly proposed.The flexible films of transition metal compounds/carbon nanofiber were synthesized by different methods,which is conducive to breaking the traditional mixing process and simplifying the battery assembly process.The specific content of this paper is as follows:（1）Carbon nanofibers（CNFs）were synthesized by electrospinning.The results show that: The surface of synthesized CNFs are smooth and the CNFs form a network structure;Although CNFs have good cycle stability,their reversible capacity is low;At a current density of 200 mA g^-1,the specific capacity of CNFs is 285.6 mAh g^-1.（2）The hybrid CoO/CNFs were synthesized by the method of condensation reflux.The results show that: In the hybrid CoO/CNFs,CoO nanosheets aggregatinginto MCF-like CoO microspheres embed in CNFs;After 150 cycles,the specific capacity of the hybrid CoO/CNFs remains 579.7 mAh g^-1 at a current density of 200 mA g^-1,including the specific capacity of 774.1 mAh g^-1 provided by CoO.（3）The hybrid FeCO₃/CNFs were synthesized by the hydrothermal method.The results show that: The structure of the hybrid FeCO₃/CNFs is like honeycomb;After200 cycles,the specific capacity of the hybrid FeCO₃/CNFs remains 546.2 mAh g^-1 at a current density of 200 mA g^-1,including the specific capacity of 919.7 mAh g^-1provided by FeCO₃.（4）The hybrid Fe₂O₃/CNFs were synthesized by the microwave hydrothermal method.The results show that: The structure of the hybrid Fe₂O₃/CNFs is like honeycomb;After 150 cycles,the specific capacity of the hybrid Fe₂O₃/CNFs remains673.8 mAh g^-1 at a current density of 200 mA g^-1,including the specific capacity of926.2 mAh g^-1 provided by Fe₂O₃.