Preparation And Modification Of Silicon-based Conductive Polymer As Anode Materials For Lithium-ion Battery

As the periodic table of the third cycle, IVA metalloid element, the outermost layers of the silicon atom has four electrode the valence electrons, the silicon has a certain electrical conductivity, and chemical properties is stable. Silicon make up about 25.7% of the total quality of earth’s crust, second only to oxygen. The theory of silicon processing capacity of 4200 mAh/g, low discharge voltage and safety performance is good, all these advantages above is to make the silicon become the focus in the lithium ion battery anode materials. However, silicon in depth to take off the intercalated-li volume effect, causing stripping from the conductive medium set fluid, and leads to poor cycle performance and coulomb efficiency low for the first time. And the conductivity of the silicon material itself is lower than metal materials limits the silicon in the commercial application in lithium ion batteries. Aiming at these problems, how to buffer the silicon in the process of circulation volume expansion, guide.This article mainly polypropylene fine(PAN), 4-(2- pyridine azo)- 1, 3-benzodiazepines(PAR) and polypyrrole(PPy) is given priority to, with silicon compound. Use all kinds of equipment, including: X-ray photoelectron(XPS), scanning electron microscope(SEM), X-ray diffraction(XRD), Fourier infrared transform spectrum(FT-IR), Raman spectroscopy(Raman) to observe the structure and appearance characteristics of materials, and analysis and research on modification of these materials is discussed in this paper. Composite was prepared by the good assembly cell, using the constant current charge and discharge, cyclic voltammetric and ac impedance test, electrochemical properties of materials for testing.By Hummer process, graphene is first, then add PAN coated with nano silicon(mass ratio: PAN: Si = 3:7) and calcined under argon atmosphere obtained after different temperature PAN @ Si composite materials. Heat treatment temperature of 300 °, to get the best PAN @ Si retest material performance, discharge capacity reached for the first time, the coulomb efficiency as for the first time after 100 weeks cycle still reversible capacity, relative to the silica nanoparticles with poly(vinylidene fluoride)(PVDF) adhesive preparation of electrodes in the first week of reversible capacity and subsequent cycle stability are improved.By adding a PAR, and USES the kind of sol-gel method with nanometer silicon elemental composition, moderate viscosity material directly daub on the copper foil, high temperature calcined under argon atmosphere, make good pre copper foil composite bonding, finally get PAR @ Si composite material, studied the different ratio and different calcination temperature on the properties of composite materials. Heat treatment temperature of 200 ° and 300 °, composite materials are showed good cycle stability. Discharge capacity reached for the first time for coulomb efficiency, for the first time after 100 weeks cycle still reversible capacity. Modification experiments, the prefetch lithium, the preparation of composite electrode and abandoned lithium battery assembly, circulation after a week, apart to install batteries. Through this method, early in the material surface to form a film of solid electrolyte interface(SEI), effectively prevent the solvent molecules through, to protect the stability of the active material on the copper foil. First discharge capacity in the process of the lithium electrode after treatment for, coulomb efficiency reached for the first time than the electrode material of lithium improves a lot.Prepared by in situ polymerization method polypyrrole(PPy), and respectively take synchronization add nano silica and the methods of preparation and then add nano silica preparation of PPy @ Si composite materials. Synchronous add method, mainly is the nanometer silicon elemental and pyrrole monomer and surfactant mixes evenly, slowly adding oxidant at low temperature, stirring constantly polymerization process, the elemental silicon by polymerization of pyrrole evenly coated, again by adding the conductive agent and adhesive preparation of anode plate; After adding method, mainly in the preparation of PPy, according to the different proportion, by adding adhesive and conductive agent material preparation after blending into the electrode.