Freestanding Porous Silicon@Heteroatom-Doped Porous Carbon Fiber Anodes for High-Performance Lithium-Ion Batteries

Silicon suffers from high volume variation and poor conductivity, which limits its commercial application in lithium-ion battery anode materials. To improve the stability of Si-based electrodes, the porous structure was designed for both Si and carbon fiber. Furthermore, heteroatom doping was adopted to enhance the conductivity of carbon fiber. Three freestanding porous silicon@heteroatom-doped porous carbon fiber was successfully prepared by coaxial electrospinning. The impact of sulfur/boron doping on the electrochemical properties of anodic materials is systematically researched. The porous structure of both silicon and carbon fiber efficiently relieves the volume expansion of silicon and provides diffusion channels for ion transportation, while the S doping can increase active sites. Relying on the distinctive structure, the porous silicon@sulfur-doped porous carbon fiber (PSi@SPCF) exhibits virtually the highest reversible capacities over the reported silicon@carbon fiber composites, with an excellent reversible capacity of 1112.7 mAh·g–1 after 1000 cycles at 2.0 A·g–1, indicating the potential application of the PSi@SPCF composites in advanced energy storage.