Preparation Of MgFe₂O₄?Ca₂Fe₂O₅ Materials And Their Electrochemical Performance

Lithium-ion batteries have the advantages of high energy density,high power density,long cycle life,etc.,and have become a new generation of green energy-saving energy.However,graphite,as a negative electrode material for lithium-ion batteries,has seriously hindered the lithium-ion battery application and development due to its low specific capacity,so the development of a new generation of lithium-ion battery anode materials has become the trend.MgFe₂O₄ and Ca₂Fe₂O₅materials were prepared and their electrochemical properties were studied.The main contents of this paper are as follows:1.The MgFe₂O₄ nanospheres were prepared by solvothermal-high temperature calcination method using iron hydroxide and magnesium acetate as raw materials,and assembled into secondary metal lithium batteries for electrochemical testing.It can be seen from the orthogonal experiment that when the hydrothermal temperature is200°C,the hydrothermal time is 24 h,the calcination temperature is 600°C,and the calcination time is 10 h,the prepared MgFe₂O₄ material has the best electrochemical performance.The synthesized MgFe₂O₄ materials were characterized by SEM,TEM,XRD and XPS.The assembled battery has a specific capacity of 1039 mAh g^-11 at a current density of 0.5 A g^-1.After 500 cycles,the specific capacity retention rate is94.21%of the first specific capacity.2.The Ca₂Fe₂O₅ nanospheres were prepared by solvothermal-high temperature calcination method using iron hydroxide and calcium hydroxide as raw materials,and assembled into secondary metal lithium batteries for electrochemical testing.It can be seen from the orthogonal experiment that when the hydrothermal temperature is180°C,the hydrothermal time is 24 h,the calcination temperature is 750°C,and the calcination time is 4 h,the prepared Ca₂Fe₂O₅ material has the best electrochemical performance.The synthesized Ca₂Fe₂O₅ materials were characterized by SEM,TEM,XRD and XPS.The assembled battery has a specific capacity of 1165 mAh g^-1at a current density of 0.5 A g^-1.After 500 cycles,the specific capacity retention rate is61.88%of the first specific capacity.3.The MgFe₂O₄ and Ca₂Fe₂O₅ materials synthesized under the optimal conditions of Chapters 3 and 4 were used as the negative electrode of lithium ion batteries,and the lithium iron phosphate was used as the positive electrode of lithium ion batteries,and the two were assembled into a lithium ion battery for electrochemical test.At a current densities of 0.5 and 8 A g^-1,the power density of MgFe₂O₄ and Ca₂Fe₂O₅lithium ion batteries is 0.21,0.23 kW kg^-1,the energy density of is 251,244 Wh kg^-1.