Controllable Preparation And Lithium Batteries Application Of Iron Oxyhydroxide And Its Derivatives

Iron oxides(FeOOH,Fe2O3,etc.)are considered as a potential electrode material because of their abundant natural resources,high theoretical specific capacity,and low operating voltage.However,as a lithium ion battery anode material,iron oxides have poor electrical conductivity and large volume changes during charge and discharge,which can easily lead to pulverization and shedding of electrode materials.At present,the solutions includes mainly producing nano-electrode materials,compounding with highly conductive materials,and designing electrode materials with unique structures.Lithium-sulfur batteries are considered to be the most promising next-generation energy storage equipment,because its weight-energy density.However,the poor intrinsic conductivity and significant volume change of sulfur cathode material and its discharge products and the "shuttle effect" of polysulfides may lead to the gradual attenuation of capacity and unsatisfactory electrochemical performance.In this paper,we use different iron sources to prepare FeOOH and its derivatives(Fe2O3,FeP)with different phases and morphologies on graphene oxide,exploring the application prospect of iron compounds in the field of lithium ion batteries and lithium sulfur batteries.(1)Utilizing the phase transition of iron oxide under hydrothermal conditions,the unique heterostructure of ?-FeOOH nanorods embedded in Fe2O3 nanospheres was prepared.As anode of lithium ion batteries,the heterostructure shows a good long cycle life under 1 A g-1,and the capacity is stable at?050 mAh g-1 after 600 cycles.The excellent electrochemical performance is benefit from the reduced content of ROCO2Li component in the SEI film,decreasing the charge transfer resistance at the electrolyte-electrode interface and improves the electrochemical reaction kinetics.(2)Mulberry-like Fe2O3 self-assembled particles on the graphene oxide was synthesized by hydrothermal method.As an anode for lithium ion batteries,the self-assembled combines the advantages of nanomaterials and bulk materials,balancing the two factors of electrochemical activity and coulombic efficiency.The initial capacity of the self-assembled at 0.2 A g-1 is 22.1%higher than that of bulk particles with similar size.In addition,the restricted SEI film exists only on the outer surface of the self-assembled to obtain a achieving a coulombic efficiency much higher than pure quantum dot electrodes.(3)Hollow sea urchin-like FeOOH precursor was synthesized by hydrothermal method using water-glycerol as solvent,further hollow sea urchin-like FeP with porous structure was obtained by phosphating in a tube furnace.As a sulfur-bearing substrate for a lithium-sulfur battery,the capacity of FeP is stable at?1000 mAh g-1 after 100 cycles at 0.1 C,much better than FeOOH precursor due to the porous structure proformed by the phosphating process provides a richer polysulfide adsorption surface.Meanwhile,the assembly between nanorods ensures the stability of electrode structure to obtain good cycle stability and high-current charge and discharge performance.