Xanthan Gum as a Carbon Source for Preparation of Carbon- Silicon/Graphite Composite as Anode Materials for Lithium Ion Batteries

摘要

Silicon anode materials have advantage of very high theoretical specific capacity (4200 mA h g?1), andlow intercalation lithium potential, but disadvantage of huge volume expansion. In this paper, xanthangum (XG) and glucose (GLU) as carbon sources, and niobium pentoxide and a dispersant are added tomodify the nano-silicon to prepare a series of carbon-silicon composite. The carbon-silicon compositeare ground with graphite to obtain the carbon-silicon/graphite composite anode material Si@XG-G.XRD tests show that these composite materials have strong characteristic diffraction peaks of graphiteand silicon, and there are no peaks of amorphous carbon. The first discharge and charge specificcapacity of Si@XG-G is 414 mA h g?1and 259 mA h g?1, respectively, with a coulombic efficiency of62.5 %. The first discharge and charge specific capacity of Si@XG/NO-G modified by adding niobiumpentoxide (NO) was 448 mA h g?1, and 285 mA h g?1, with a coulombic efficiency of 63.6 %. Whenmixing the carbon-silicon composite that is doped by niobium pentoxide with graphite to prepare thecarbon-silicon/graphite composite anode material, the first charge and discharge specific capacity aswell as the coulombic efficiency of the composite anode materials are significantly improved. Inaddition, when modified by polyvinylpyrrolidone (PVP) again, the first discharge specific capacity andcharge specific capacity of Si@XG/NO/PVP-G is 671 mA h g?1and 489 mA h g?1, respectively, with acoulombic efficiency of 72.9%. Obviously, the active material Si@XG/NO/PVP-G has a furtherimproved specific capacity and coulombic efficiency.