Embedding Atomically Dispersed Iron Sites in Nitrogen‐Doped Carbon Frameworks‐Wrapped Silicon Suboxide for Superior Lithium Storage

Abstract

Abstract Silicon suboxide (SiOx) has attracted widespread interest as Li‐ion battery (LIB) anodes. However, its undesirable electronic conductivity and apparent volume effect during cycling impede its practical applications. Herein, sustainable rice husks (RHs)‐derived SiO2 are chosen as a feedstock to design SiOx/iron–nitrogen co‐doped carbon (Fe–N–C) materials. Using a facile electrospray‐carbonization strategy, SiOx nanoparticles (NPs) are encapsulated in the nitrogen‐doped carbon (N–C) frameworks decorating atomically dispersed iron sites. Systematic characterizations including high‐angle annular dark‐field scanning transmission electron microscopy (HAADF‐STEM) and X‐ray absorption fine structure (XAFS) verify the existence of Fe single atoms and typical coordination environment. Benefiting from its structural and compositional merits, the SiOx/Fe–N–C anode delivers significantly improved discharge capacity of 799.1 mAh g−1, rate capability, and exceptional durability, compared with pure SiO2 and SiOx/N–C, which has been revealed by the density functional theory (DFT) calculations. Additionally, the electrochemical tests and in situ X‐ray diffraction (XRD) analysis reveal the oxidation of LixSi phase and the storage mechanism. The synthetic strategy is universal for the design and synthesis of metal single atoms/clusters dispersed N–C frameworks encapsulated SiOx NPs. Meanwhile, this work provides impressive insights into developing various LIB anode materials suffering from inferior conductivity and huge volume fluctuations.

Keywords

• atomically dispersed iron sites
• catalytic attribute
• Li‐ion‐battery anodes
• nitrogen‐doped carbon frameworks
• silicon suboxide