The Preparation And The Electrochemical Performance Of Iron-Based Negative Materials For Lithium Ion Batteries

Lithium ion battery is a new type of device for Energy Storage.Due to its significant advantages as convenient,safety,higher performance,there is a wide range of needs from the portable electronic devices to electric vehicles and many other fields.Under this background,a lot of researchers have gone into the researche and development of lithium ion battery.At present,the commercialization of lithium ion battery cathode material such as LFP has been widely recognized by the society, but it also has disadvantages of low tap density,poor conductivity etc.The anode material which widely used at present is graphite graphite anode material, but also has its disadvantages, such as overcharge poor stability, poor specific capacity.To this end,we provide some new materials and modification as iron anode materials and special morphology of Co3O4.Application ofscanning electron microscopy(SEM),transmission electron microscopy (TEM), X-ray diffraction (XRD), cyclic voltammetry (CV), thermogravimetric analysis (EG), XPS, EDS and battery testing system is preparede for the test of electrochemical properties and physical properties of materials. The main idea is:LFP microspheres which prepared by a low-temperature and template-free solvothermao method.Fe3O4doped with W,SnO2and comprove the qustion refered before.1.Monodisperse LFP microspheres have been prepared successfully by a low-temperature and template-free solvothermal method on a large scale.The uniform microspheres are composed of aggregated nanoparticles with an open three-dimensional interconnected porous microstructure.These micro/nanostructured LFP microspheres exhibit a high tap density (1.5g cm3) and, as cathode materials, show remarkably high rate capability as high as109mAh g-1at5C rate and99mAh g-1at10C rate, and good cycle stability. The porous LFP electrode materials can find their way for the application in high-power lithium-ion batteries.2.This work presents a hydrothermal synthesis of W-doped Fe3O4nanoparticles. The results indicate that Fe2+but not Fe3+is substituted withW6+. Both undoped and doped Fe3O4show ferromagnetic behaviors.The magnetism of Fe3O4decreases from7.2emu g-1to5.0emu g-1after doping, because the superexchange interactions between Fe2+and Fe3+are hindered by W. Interestingly, W-doped Fe3O4exhibits improved reversible capacity of629mAh g-1in comparison with341.3mAh g-1of pure Fe3O4for their first charge/discharge cycle, and shows higher initial Coulombic efficiency of86.1%. Moreover, better cyclic stability has been obtained for W-doped Fe3O4. W-doped Fe3O4nanoparticles were prepared with a hydrothermal method. The XRD, TEM and XPS measurements proved that doping of W6+would increase the lattice constants and oxidation state of Fe2O4The superexchange interactions between Fe2+and Fe3+are hindered by doped W, inducing the magnetism decrease. The W doping increases the lattice constants and prevents Fe aggregation during the charge-discharge cycle, resulting in higher reversible capacity and improved cyclic stability.3.A facile strategy is presented for the preparation of carbon coated nanosized SnO2-Fe2O3composite. The in situ polymerization of PANI not only prevents the agglomerate and particle growth in sol-gel and thermal treatment processes, but also guarantees the full carbon coating and good conductive contact property between SnO2-Fe2O3and carbon shell. The unique structure of SnO2-Fe2O3@C nanocomposite effectively improves its electrochemical properties, achieving the fully reversible reaction and alloy reaction of SnO2. The composites reported herein, which deliver excellent cycling capacity and rate performance, will be a promising candidate a’s anode materials for LIBs.4.Unique mesoporous Co3O4octahedra are prepared with the sol-gel method as negative electrode material for lithium-ion batteries. Such an interesting nanostructure that has inherited the combined advantages of anisotropy morphological structure stability and porous feature, which can buffer the volume changes during the electrochemical cycles and shorten the diffusion path of Li+/electron transport, exhibits remarkable electrochemical performance.5.Mesoporous Co3O4nanorods have been synthesized through the hydrothemal method followed by calcination treatment.Taking advantage of the mesoporous structures and1D feature,mesoorous Co3O4nanorods exhibit high reverisble capacity,excellent cyclix stability,and superior rate capability.A specific capacity as high as～1200mAh g-1is retained after260cycles at current density of200mA g-1is retained after260cycles at current density of200mA g-1.At high rate of1A g-1,it delivers the capacity of～490mA g-1after280cycles.The results make the mesoporous Co3O4nanorods a promising candidate for LIB anode.