Research On Preparation And Lithium Ion Battery Of LiFe₅O₈ Anode Material Based On Iron

At present,the industrialized production of lithium-ion battery anode material mainly consists of graphite materials and Si-C materials.Graphite materials have advantages such as good conductivity and a wide range of sources,but their lower theoretical specific capacity cannot meet the development of high energy density energy storage equipment.Although Si-C anode materials have extremely high theoretical specific capacity,the significant volume changes during cycling seriously affect their cycling life and performance.Therefore,developing high specific capacity anode materials is currently one of the main tasks of research.LiFe₅O₈ has the advantages of high theoretical specific capacity,low cost and good safety,and is considered a potential anode material for high energy density Li-ion batteries.However,there are still some issues that need to be addressed when it is used as an anode material.During the cycling process,the volume changes of LiFe₅O₈ lead to material pulverization and detachment.Besides,its lower electronic conductivity limits its further application.In order to solve the above problems,LiFe₅O₈is combined with highly conductive carbon materials to improve its electronic conductivity and alleviate its volume expansion during cycling,thereby enhancing its rate performance and cycling life.The specific research content and results are as follows:1.The CNTs was introduced to modify LiFe₅O₈ and obtained LiFe₅O₈/CNTs composite materials,aiming to improve the electronic conductivity of the material while alleviating its volume expansion during cycling.The research results showed that the LiFe₅O₈/CNTs 3%sample exhibited excellent cycling performance,with a capacity of up to 427.3 m Ah·g^-1 after 50 cycles at 0.5 C and 331.7 m Ah·g^-1 after 200 cycles at 1 C,both of which were much higher than the original sample.Moreover,at a high rate of 2C,the LiFe₅O₈/CNTs 3%sample exhibited a discharge specific capacity of 264.8 m Ah·g^-1.2.The introduction of rGO improved the electronic conductivity of LiFe5O8 anode material and alleviated its volume expansion.The research results indicated that rGO formed a conductive network between materials,greatly promoting the flow of electrons between materials.The LiFe5O8/rGO 5%sample provided a discharge specific capacity of 284 m Ah·g^-1 at a high rate of 2 C,which was much higher than the original sample.The LiFe5O8/rGO 5%sample has a capacity of up to 524.3 m Ah·g^-1 after 50 cycles at0.5 C,and a capacity of up to 369.3 m Ah·g^-1 after 200 cycles at 1 C,both of which were much higher than the original sample.3.LiFe₅O₈@C anode is synthesized through low temperature thermal decomposition of organic carbon sources.The research results showed that the effect of carbon coating using sucrose as the carbon source is the best.After cycling for 50 cycles at a rate of 0.5 C,the discharge specific capacity can be maintained at 400.8 m Ah·g^-1.After cycling for 200 cycles at a high rate of 1 C,the sucrose carbon coated sample still exhibits a high specific capacity of 313.3 m Ah·g^-1.Moreover,at a high rate of 2 C,the sucrose carbon coated sample still exhibites a high discharge specific capacity of 215.6m Ah·g^-1.