Red Phosphorus Hybridized with Silicon Nanoparticles Encapsulated in Nitrogen-Doped Carbon Nanotubes Composite for Lithium-ion Secondary Batteries

Lithium-ion batteries (LIBs) are valued for their lightweight nature, long cycle life, and high energy density, which make them ideal for use in electric vehicles and portable electronics. Recently, red phosphorus (P) has been identified as a potential anode material with a theoretical specific capacity of 2,596 mAh g⁻¹. However, its low conductivity (10⁻¹² Sm⁻¹) and significant volumetric expansion during cycling limit its effectiveness. On the other hand, silicon (Si) has a theoretical capacity of approximately 3,579 mAh g⁻¹ but is problematic because it experiences over 400% volume expansion during lithiation and delithiation. This study presents a silicon and nitrogen-doped carbon nanotube (CNT) composite integrated with red phosphorus, prepared using a simple and scalable process. The P/Si/NCNT composite mitigates harmful electrode/electrolyte reactions, while stabilizing performance during charge-discharge cycles. By combining high-capacity silicon and red phosphorus, the composite achieves enhanced capacity and conductivity while minimizing volume fluctuations by hybridization with CNTs. Electrodes displayed an initial discharge capacity of 2025 mAhg⁻¹ at 100 mAg⁻¹ with a high reversible capacity of 515/521 mAh g⁻¹ after 100 cycles. The prepared composite exhibited good rate capability with 342 mAh g⁻¹ discharge capacity at 1000 mAg⁻¹ after a long 200 cycles, demonstrating excellent rate capability. The enhanced electrochemical performance can be attributed to the synergistic effects of the P/Si blend and the conductive nitrogen-doped CNT framework, highlighting potential advancements in sustainable energy storage solutions.