Enhancement of lithium-ion battery anodes performance by anchoring silicon-carbon nanofibers in porous biochar frameworks

Silicon-based anode materials have attracted significant interest due to their high theoretical specific capacity. However, their practical application is severely hindered by the substantial volumetric expansion during cycling. To overcome this limitation, a novel silicon-carbon nanofiber/carbonized Poria powder composite was synthesized via electrospinning followed by a simple heat treatment process. The carbonized Poria powder features a hierarchical porous structure, combining macropores and mesopores. The macropores effectively trap and constrain the silicon-carbon nanofibers, thereby enhancing the structural stability, while the mesopores increase the specific surface area, facilitating improved electrolyte penetration. The composite benefits from the conductive framework of nitrogen-doped carbon fibers and carbonized Poria powder, which collectively enhance its electrochemical performance. At a current density of 0.1 A g(-1), the composite exhibits an initial discharge capacity of 1579.7 mAh g(-1) and a charge capacity of 1455.5 mAh g(-1). After 1000 cycles, the discharge capacity is maintained at 1277.2 mAh g(-1), corresponding to a capacity retention rate of 80.8%. Additionally, at a scan rate of 0.5 mV s(-1), the composite demonstrates a high pseudocapacitive contribution of 91.56%, which improves the lithium-ion diffusion rate, reduces cycling-induced stress and side reactions, and mitigates capacity degradation over extended cycling.