Research Of The Transition Metal Phosphide And Oxides As Anode Materials For Lithium Ion Batteries

The contradiction between fossil energy consumption and increasing energy demand become more serious,so scientists focused on developing novel green energy.Lithium ion battery,as a clean recyclable energy,relies mainly on working with lithium ion shuttle between positive and negative electrodes.More attention has been paid by researchers because of its advantages of green environmental protection,fast charging,high energy density and so on.In recent years,commercial carbon materials are often used as the traditional anode materials for lithium ion batteries.However,the application of carbon in lithium ion batteries is limited by their low theoretical capacity.For example,it cannot meet the high energy demand of automobile power energy.In order to further promote the application market of lithium ion batteries,the development of high capacity negative electrode has become a major focus of scientists'research.This paper mainly designed transition metal phosphides and oxides as anode materials for lithium ion batteries,and studied the electrochemical properties and the corresponding application of these materials.The relevant contents are as follows:1.Interconnected Ni₂P nanorods grown on nickel foam for binder free lithium ion batteriesNickel phosphide?Ni₂P?is often concerned by researchers because of its good catalytic and low polarization characteristics,but it is limited by the rapid capacity attenuation in the practical application of anode materials for lithium ion batteries.For solving this problem,we introduced the advantages of the large specific surface area of the nickel foam?NF?and successfully prepared Ni₂P/NF nanorods to increase the specific surface area of the Ni₂P/NF composite.Owning to NF itself can be utilized as a nickel source and a metal collector,Ni₂P/NF can be used as a self-supported and binder-free integrated electrode material.The results of the test data show good lithium storage and recycling reversibility during the cycle process,which benefited to the electrical conductivity of the Ni₂P/NF material.We hope this work can provide a potential system for preparation metal phosphides on lithium ion batteries,catalysis or other field.2.Porous Fe₂O₃-C microcubes as anodes for lithium-ion batteries by rational introduction of Ag nanoparticlesFe₂O₃ is one of the potential candidates as anode material for the lithium ion batteries because of its high theoretical specific capacity and low conversion potential.The poor conductivity of the negative electrode and the volume effect during cycling process are the main factors that restrict the application and development of lithium ion batteries.To overcome these problems,we successfully introduced high conductivity silver particles?Ag?into Fe₂O₃-C materials through dopamine reduction and carbonization procedure.The data showed that when the good conductivity of Ag nanoparticles?10%?was introduced,the Fe₂O₃-C-Ag-10 composite showed good reversible capacity and cycling performance.When tested at a larger current density of 1000 mA g^-1,the electrode material can still maintain a good capacity of 538 mAh g^-1 after 700cycles.It can be owing to the carbon and silver in the composite with porous structure can improve the stability and conductivity of the hybrid material in a certain extent,so the Fe₂O₃-C-Ag material exhibits excellent electrochemical performance.This new design idea may provide an application prospect for preparation a new type anode material for lithium ion batteries.3.In-situ carbonization for template-free synthesis of MoO₂-Mo₂C-C microspheres as high-performance lithium battery anodeMolybdenum oxide?MoO₂?has high theoretical capacity(838 mAh g^-1)for lithium ion battery anode,but it still exists some problem of capacity attenuation and volume expansion during cycling process after a long time.In order to solve these problems,the MoO₂-Mo₂C-C anode material was prepared by in-situ synthesis method.In addition,by adjusting the mass ratio of Mo and dopamine,the content of carbides can be regulated to further change the capacity of the electrode material.The data results show that the MoO₂-Mo₂C-C has good cyclic stability and high multiplier performance owning to the good conductance of Mo₂C and C.When tested at current density of 100 mA g^-1,the electrode material can maintain pretty capacity of 1188 mAh g^-1after 250 cycles.This good electrochemical performance has a certain potential value in the basic research and application of lithium ion batteries anode materials.