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.