Study On Preparation And Modification Of Fe-Based Lithium Ion Batteries Electrode Materials Using Pickling Iron Oxide Red

In order to realize the high added value utilization of the pickling iron oxide red,theα-Fe2O3,FeS,and LiFePO4/C electrode materials were prepared by pickling iron oxide red as raw materials.However,due to the volume expansion of α-Fe2O3 and FeS,and the poor conductivity of LiFePO4,the application of these electrode materials is limited.In this paper,the above electrode materials were modified by doping,preparation of composite materials and carbon coating.The Cr-doped α-Fe2O3 anode material was prepared by a simple solid-phase method under an inert atmosphere.The first-principles calculations showed that Cr doping can reduce the band gap of α-Fe2O3,leading to the appearance of impurity levels and improved electrical conductivity.At the same time,the results of XPS analysis indicated that the electronic compensation of high-valent ions and the appearance of oxygen vacancies may be important reasons for improving the electrochemical performance ofα-Fe2O3.The electrochemical test results showed that the best electrochemical performance was obtained for samples with 4%doping.At a current density of 0.1 Ag-1,the discharge/charge specific capacity was as high as 1624/1065.9 mAh g-1,and the reversible specific capacity of 971.3 mAh g-1 can be maintained after 150 cycles.Using pickling iron oxide red as the iron source,a simple in-situ vulcanization and solid phase method was used to prepare pure FeS and FeS/Fe3O4 composites with different composite ratios by controlling the addition amount of sulfur source.The electrochemical tests showed that the unique composite structure can significantly improve the comprehensive electrochemical performance of FeS,indicating that the synergistic effect between FeS and Fe3O4 was an important reason to improve electrochemical performance.At a current density of 0.1 A g-1,the initial discharge and charge specific capacities were 1182.0 and 994.7 mAh g-1,respectively.The reversible capacity of 414.8 mAh g-1 was maintained after 300 cycles at a current density of 0.5 A g-1.LFP/C cathode material was prepared by pickling iron oxide red as iron source.The experimental conditions were optimized by orthogonal experiments,and then doped modification was performed on this basis,preferably 3%Cl-doped LFP/C positive electrode material.Electrochemical tests showed an initial specific capacity of 164.1 mAh g-1 at a current density of 0.1 C.It was first cycled at a current density of 0.1 C for 100 cycles and then maintained at a current density of 10 C for 500 cycles to still can maintain a reversible specific capacity of 96.4 mAh g-1.