Preparation and Electrochemical Performance of Anode for High-Performance Silicon-Based Composite Lithium-Ion Battery

Silicon has become the most promising anode material for lithium-ion batteries since its theoretical lithium intercalation capacity is as high as 4200 mA·h/g. However, its commercial application as a negative electrode for Li-ion batteries is limited due to the huge volume expansion (≥300%) during intercalation and delithiation. In this paper, a C@Si/C silicon-based composite anode was prepared by an electrospinning technique with carbon source precursor coating. The phase structure and microstructure of the material were characterized by X-ray diffraction and scanning electron microscopy. The change of the quality of the obtained material after polyvinypyrrolidone coating with temperature was investigated by thermo-gravimetric analysis. Graphite transformation degree of the silicon-based negative electrode material obtained after carbonization was determined by Raman spectroscopy. The prepared silicon-based anode materials were analyzed by galvanostatic charge–discharge, cyclic voltammetry and alternating current impedance spectroscopy. The results show that the electrochemical performance of the carbon-coated electrospun Si/C fibers is improved compared to the uncoated fibers. At a current density of 0.1 A/g, the first discharge capacity can reach 1401.4 mA·h/g, the first coulombic efficiency is as high as 70.22%, and the capacity remains at 582.6 mA·h/g after 100 cycles. The results of rate test show that after a large current density test of 1.0 A/g, C@Si/C silicon-based composite anode still has a reversible capacity of 622.2 mA·h/g at a current density of 0.1 A/g.