Preparation And Properties Of Fe-based And V-Based Phosphate/Carbon Composite Cathode Materials

The energy and environment are facing great challenges due to the increasing richness of human-life types and the excessive use of fossil fuels.Solving the energy and environment problems has become a key issue for human development.For the sake of environmental health,the use of electric vehicles and electric motorcycles is the preference goal of social development and good environment.The development of electric vehicles and electric motorcycles has promoted the development of lithium-ion batteries,as well as the development of cathode materials for lithium-ion batteries.The polyanion compound cathode material is the preference for the research of cathode materials of power lithium-ion batteries due to its high voltage platform,high rate performance and high cycle performance.In this case,the key to study the cathode materials of power battery is to study Fe-based and V-based phosphate/C composite cathode materials.Fe and V-based phosphate anode materials were prepared by choosing different carbon matrix,in which the carbon matrix can be synthesized by chemicals or by selecting solid waste biomass.Using solid waste biomass carbon matrix can turn waste into treasure and avoid waste and environmental pollution.In this paper,three kinds of Fe-based and V-based phosphate/C composite cathode materials with different structures were prepared by evaporation self-assembly and repeated impregnation of different carbon matrix,and the structure,morphology and other physical properties of the materials were analyzed by a variety of characterization techniques.The composite cathode materials are assembled into a button type battery,and the influence of the electrode material with special structure on its performance is analyzed by using a variety of test and analysis techniques.The ultra-thin nanoflakes structure Li Fe PO₄/C composite cathode material was prepared via evaporation self-assembly method with square acid as precursor preparation for the matrix.When the voltage range is 2.5-4.2 V,the specific capacity of Li Fe PO₄/C composite cathode material is still 98.5 m Ah/g at high rate charge discharge of 20 C.The porous and nitrogen-doped structure Li₃V₂?PO₄?₃/C composite cathode material was prepared via repeated impregnation method with the oroxylum fibers as the matrix.When the voltage range is 3.0-4.3 V and the current density is10 C,it has a higher discharge specific capacity of 87.4 m Ah/g.The lotus root-like structure Li₃V₂?PO₄?₃/C composite cathode material was prepared via repeated impregnation method with the dandelion fibers as the matrix.When the voltage range is 3.0-4.3 V and the current density is10 C,it has a higher discharge specific capacity of 116.7 m Ah/g.The ultra-thin nanoflakes,porous and lotus root-like structure can provide an effective and fast channel for the transmission of Li⁺and electrons,which makes the Li Fe PO₄/C composite cathode material and Li₃V₂?PO₄?₃/C composite cathode material have excellent electrochemical performance.