Porous silicon/carbon composite for high-performance lithium-ion batteries

Silicon anodes are promising candidates for lithium-ion batteries. However, their practical application is severely limited due to their significant volume expansion leading to irreversible material fracture and electrical disconnection. This study proposes a new top-down strategy for preparing microsized porous silicon and introducing polyacrylonitrile (PAN) as nitrogen-doped carbon coating, which is designed to maintain the internal space and alleviate the outward expansion of the silicon anode during the lithiation and delithiation process. Subsequently, we explored the effect of temperature on the thermal transition behavior of PAN and the electrochemical behavior of the composite electrode. After the treatment at 400 °C, the PAN coating retained a high nitrogen doping content of 11.35%, which explicitly confirmed the existence of C―N and C―O bonds that improved the ionic-electronic transport properties. This treatment not only retained a more intact carbon layer structure, but also introduced carbon defects, exhibiting remarkably stable cycling even at high rates. When cycled at 4 A g⁻¹, the optimized anode exhibited a specific capacity of 857.6 mAh g⁻¹ even after 200 cycles, demonstrating great potential for high-capacity energy storage applications.