Agar-coated and NH4F Modified Nanosilicon as Anode Material for Lithium-ion Battery
Silicon anode material becomes one of the ideal materials for high energy density lithium-ion battery,due to its low cost,high specific capacity and reliable safety.However,severe volume expansion during lithium embedding,poor material conductivity and poor cycling stability limit the commercial application of silicon anode material.Therefor,agar-derived carbon/NH4F@nanosilicon composites(Si@FNC)were prepared by using a one-pot sol-gel method with agar and NH4F to realize carbon coating and doping modification.Structure,morphology and electrochemical properties of the Si@FNC composites were studied.Cyclic stability and electrical conductivity of the Si@FNC composites were significantly improved after NH4F modification.When the mass ratio of NH4F to Si was 1∶5,the first discharge specific capacity was 2001.0 mAh·g-1 at a current density of 500 mA·g-1,while the residual capacity was still maintained at 836.7 mAh·g-1 after 200 cycles.The results could be used as a reference for further exploration of high-capacity silicon-carbon anode materials.
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