Robust Nitrogen/Sulfur Co‐Doped Carbon Frameworks as Multifunctional Coating Layer on Si Anodes Toward Superior Lithium Storage

Abstract Silicon (Si)‐based anodes hold great potential for next‐generation lithium‐ion batteries (LIBs) due to their exceptional theoretical capacity. However, their practical application is hindered by the notably substantial volume expansion and unstable electrode/electrolyte interfaces during cycling, leading to rapid capacity degradation. To address these challenges, we have engineered a porous nitrogen/sulfur co‐doped carbon layer (CBPOD) to uniformly encapsulate Si, providing a multifunctional protective coating. This innovative design effectively passivates the electrode/electrolyte interface and mitigates the volumetric expansion of Si. The N/S co‐doping framework significantly enhances electronic and ionic conductivity. Furthermore, the carbonization process augments the elastic modulus of CBPOD and reconstructs the Si‐CBPOD interface, facilitating the formation of robust chemical bonds. These features collectively contribute to the high performance of the Si‐CBPOD anodes, which demonstrate a high reversible capacity of 1110.8 mAh g −1 after 1000 cycles at 4 A g −1 and an energy density of 574 Wh kg −1 with a capacity retention of over 75.6% after 300 cycles at 0.2 C. This study underscores the substantial potential of the CBPOD protective layer in enhancing the performance of Si anodes, providing a pathway for the development of composite materials with superior volumetric energy density and prolonged cyclic stability, thereby advancing high‐performance LIBs.