Preparation And Electrochemical Performances Of Fe And Cu Based Anode Materials

Lithium-ion batteries are widely used in portable electronic devices,new energy vehicles and other fields due to their high energy density and long cycle life.Lithium-ion capacitors have attracted much attention because of their high power density,high energy density and long cycle life.Sodium ion batteries have attracted the attention of researchers because of their abundant and low cost.At present,the anode materials for the above mentioned energy storage devices have not been able to meet the needs of market development,forcing us to look for cathode materials with excellent electrochemical performance.Among all kinds of new cathode materials at present,iron and copper based anode materials have high theoretical specific capacity and abundant reserves,etc.,which attract much attention.However,iron and copper-based anode materials have some problems,such as poor conductivity and serious volume effect,which seriously affect the cycle stability of the battery.This paper mainly focuses on the preparation and electrochemical performances of iron and copper based anode materials,the content is as follows:(1)Using ferric nitrate,glucose,thiourea and melamine as experimental materials,nitrogen-phosporous co-doped carbon coated Fe₃C composites(Fe₃C/NSC)were prepared by mixed grinding and subsequent sintering process.The high specific surface area and abundant defects of the composite not only promoted the ion transfer,but also provided more active sites.More importantly,Fe₃C catalysis can catalyze the reversible conversion of certain components of the solid electrolyte interface,providing additional capacity during the cycling.When Fe₃C/NSC is used as anode material for lithium-ion batteries,it has a reversible capacity of 597 mAh g^-1after 500 cycles at a current density of 1 A g^-1;It has a reversible capacity of 366 mAh g^-1after 1600 cycles at a current density of 4 A g^-1.(2)Using ferric nitrate,phytic acid,thiourea and melamine as experimental materials,nitrogen-phosporous co-doped carbon coated FeP composites(FeP/NSC)were prepared by mixed grinding and subsequent sintering process.Because of the cooperative hydrogen bonding between melamine and phytic acid,the two-dimensional structure of porous carbon coated FeP can be formed.This porous structure is largely conducive to the penetration of electrolyte and shortening the ion transfer distance.In addition,the carbon material on FeP surface can significantly alleviate the volume change and improve the electrical conductivity after cycling.When FeP/NSC is used as anode material for lithium-ion batteries,it has a reversible capacity of 293.0 mAh g^-1after 2000 cycles at a current density of 4 A g^-1.Even at the current density of 6 A g^-1,there is still a reversible capacity of 218.3 mAh g^-1.A lithium ion capacitor was assembled with FeP/NSC composite as the anode material and porous carbon as the cathode material.The energy density reached 91.4 Wh kg^-1at the power density of 390 W kg^-1,and the energy density reaches 54.7 Wh kg^-1at the power density of 5 kW kg^-1.(3)Using copper foam,sodium hydroxide and ammonium persulfate as raw materials,CuO/Cu₂O heterostructure arrays were prepared on the copper foam by hydrothermal and subsequent calcination process.CuO/Cu₂O nanosheet arrays with unique three-dimensional structure have abundant porous structure,which is obviously conducive to electrolyte penetration and Na⁺diffusion.When the CuO/Cu₂O heterostructure array is used as the cathode material of sodium ion battery,it has a reversible capacity of 1.0 mAh cm^-2after 50cycles at a current density of 0.6 mA cm^-2.The reversible capacity of 0.56 mAh cm^-2is obtained even at a high current density of 2.0 mA cm^-2.The sodium ion battery assembled with CuO/Cu₂O as cathode material and Na_xCoO₂as cathode material has a reversible capacity of 0.20 mAh cm^-2after 100 cycles at a current density of 0.5 mA cm^-2.