Study On The Modification Of Fe₂O₃ Anode Material And Its Lithium Battery Performance

Lithium-ion batteries are easy to carry and have high energy density and are widely used in mobile phones,computers and electric vehicles.Graphite materials are rich in resources and low in price,and have become the anode materials for commercial applications of lithium ion batteries.However,the theoretical capacity of graphite is only 372mAh/g,which limits its application in high-capacity devices.Fe2O3 has a high theoretical specific capacity(1007mAh/g)and is one of the ideal anode materials.However,in the process of charge and discharge,with the intercalation and deintercalation of lithium ions,Fe2O3 will exhibit a significant volume expansion,and the material rapidly pulverized and the discharge capacity will be seriously attenuated.Among the anode materials of lithium ion batteries,TiO2 has the advantages of high capacity,abundant resources,environmental friendliness,good structural stability and high safety performance,and has a good application prospect.During charging and discharging,TiO2 has a high charge and discharge platform(1.5V),which avoids the formation of lithium dendrites and has high safety.A small amount of Fe2O3 was incorporated into anatase TiO2,and the high expansion of Fe2O3 was solved by the stability of TiO2.Fe2O3 was coated with a carbon material with a small deformation rate,and the carbon material outside Fe2O3 bound Fe2O3 to solve the problem of high expansion.(1)First,a Fe2O3-doped TiO2 microsphere material having a size of about 2m was synthesized by a one-step hydrothermal method.The phase,morphology,internal structure and charge and discharge properties were tested by XRD,SEM,TEM and electrochemical methods.The results show that the charge-discharge specific capacity of Fe2O3 doped TiO2 material is greatly improved.For the first time,the second and fifth discharge specific capacities of Fe2O3 doped TiO2 materials were 659mAh/g,646mAh/g and 580mAh/g,respectively.After doping with Fe203,the charge-discharge performance of the material is greatly improved,and the cycle stability of Fe2O3 is also greatly improved.(2)Then,a carbon-coated Fe2O3 nano sphere material of about 50nm was synthesized by a one-step hydrothermal method.The carbon material outside Fe2O3 is used to solve the problem of high expansion rate of Fe2O3 and improve the stability of Fe2O3 cycle.The phase,morphology,internal structure and charge and discharge properties were tested by XRD,SEM,TEM and electrochemical methods.The results show that the carbon layer in the synthesized carbon-coated Fe2O3 material is an amorphous carbon material,which increases the conductivity of Fe2O3 and increases the transmission efficiency of lithium ions.The carbon-coated Fe2O3 had a first discharge specific capacity of 1914mAh/g,and the second and fifth discharge specific capacities were 1224mAh/g and 1087mAh/g,respectively.Compared with pure Fe2O3,the first discharge capacity of carbon-coated Fe2O3 is 190%of the theoretical specific capacity of Fe2O3,the capacity attenuation is greatly improved,and the cycle was 812mAh/g.Accelerate the speed of commercial application of Fe2O3,expperformance is better.After 50charge and discharge cycles,the discharge specific capacity lore the theory of Fe2O3,and provide theoretical guidance for the future research of Fe2O3.