Preparation And Electrochemical Properties Study Of Si-Sb/C Alloy Anode Materials

Since the early 1990 s,lithium-ion batteries(LIB)have been most widely utilized as power sources storage device for various commodities,ranging from portable electronic devices to electric(or hybrid)vehicles.There is a growing demand on advanced LIBs with higher specific capacity and longer cycling performance.Commercialized anodes(graphitic carbon),however,have been obstacles to achieving this because of their low specific capacity(372 mAhg-1),promoting various and vast research towards advanced LIBs,in particular anode materials.Si anodes have shown,however,critical limitations due to large volume expansion(400%)and thus pulverization and electrical contact loss during lithiation and delithiation processes.In order to overcome the aforementioned demerits,many researches have been dedicated to understanding the lithiation behavior of silicon anodes using various methods.In this paper,ternary silicon-based composites were prepared by both doping with inertium antimony(Sb)and coated with carbon,so as to improve the electrochemical properties of silicon-based anode materials and control the morphology of materials.1.The ternary Si-Sb/C composite anode material was prepared using polyaniline(PANI)as the carbon source by chemical reduction method,physical mechanical ball milling and subsequent high temperature calcination.The doping of inactive metal antimony(Sb)can not only serve as a buffer matrix to effectively buffer the bulk effect of the silicon-based material but also improving the electrical conductivity of the material.Polyaniline(PANI)as a carbonaceous material,it has a excellent conductivity and high electrochemical activity,and it can also form a carbon shell after sintering at high temperature to inhibit the volume expansion of silicon.In this paper,the sintering temperature,the electrochemical properties of the materials prepared by different PANI materials,and the influence of different test temperatures on the electrode materials was studied.The results show that the carbon-coated material has a better cycling stability than uncoated carbon material obviously.In several proportions,the 30% PANI of Si-Sb/C composite anode material has the best cycle stability,the initial discharge capacity of the electrode is 937.1 mAh/g,the coulombic efficiency is up to 78.58% at first cycle and the capacity retention is 78.58% after 50 cycles.2.The ternary Si-Sb/C composite anode material was prepared using polyacrylonitrile(PAN)as carbon source by mechanical ball milling and subsequent carbothermal reduction method.Polyacrylonitrile(PAN),as a conductive polymer,it was widely used as a precursor to synthesis carbon materials and more environmentally friendly compared to polyaniline(PANI).What's more,its cyclization reaction during the carbonation process can form a stable trapezoidal structure.In this paper,the sintering temperature of the material was studied.The specific composition of the material was analyzed by X-ray diffraction(XRD)and X-ray Energy dispersive spectroscopy(EDS).The electrochemical properties of the materials prepared by different PAN materials and the influence of different binders on the cycling performance of the electrode materials were studied.The results show that the 40% PAN of Si-Sb/C composite anode material has the best electrochemical performance,the initial discharge capacity of the electrode is 2602.2 mAh/g,the first Coulomb efficiency is 87.98%,while its cycle stability is relatively good.The choice of different binders has an important effect on the electrochemical properties of the materials.Compared with the oil-based polyvinylidene fluoride(PVDF)and the aqueous sodium alginate(SA),when CMC is used as the binder,the electrochemical properties of the material are the best.3.In order to further improve the electrochemical properties of materials and to relief the capacity attenuation of materials,the morphology of materials were changed based on compound.While the nanofibers can accommodate the volume changes and deal with horizontal and vertical pressure accumulation,thus ensuring the stability of the electrode structure.In this paper,Si-Sb/C nanofiber composite anode materials were prepared by electrospinning and subsequent carbothermal reduction.The calcination temperature of the material was investigated by Thermogravimetric Analysis(TG).The composition and crystallinity of the materials were analyzed by X-ray diffraction(XRD)and Energy dispersive X-ray analysis(EDS).The morphology of the materials were analyzed by Scanning electron microscopy(SEM)and Transmission electron microscopy(TEM).The electrochemical properties of the materials were also investigated.The results show that when the mass ratio of Si to antimony acetate is 1: 4,the first discharge capacity of the electrode is the highest,reaching 1164.2 mAh/g,and its cycle stability is the best,the capacity is 725.5 mAh/g and capacity retention is 62.3% after 50 cycles.