Facile spray-drying/pyrolysis synthesis of core-shell structure graphite/silicon-porous carbon composite as a superior anode for Li-ion batteries

A silicon/graphite/amorphous carbon (Si/C) composite with a low silicon content in a core-shell structure has been easily synthesized using a simple method based on spray drying in combination with a subsequent pyrolysis process; natural graphite serves as the core, and silicon nanoparticles, which filled in the porous carbon matrix formed from the pyrolysis of citric acid and pitch precursors, serve as the shell. The combination of the core-shell structure for the composite and porous carbon-coating layer accommodates the large volume change of the silicon during the lithium intercalation/extraction process, thus stabilizing the electrode structure during discharge/charge cycles. As an anode material, the as-obtained Si/C composite demonstrates high capacity and excellent cycle stability. An initial specific discharge capacity of approximately 723.8 mAh g^-1 and a reversible specific capacity of approximately 600 mAh g^-1 after 100 cycles at a constant density of 100 mA g^-1 are reached, about two times the values for graphite. Due to the simple synthesis process and the excellent performance of the resulted electrode, great commercial potential is envisioned.