Internal Buffering-Interfacial Regulation Synergy Bridges Stability and Kinetics in Microsized Silicon-Carbon Anodes

Microsized Si/C composite anodes are promising for practical lithium-ion batteries due to their high tap density and scalability. However, their performance remains constrained by structural degradation and an unstable solid electrolyte interface (SEI), and current strategies fail to address the intrinsic coupling between interfacial chemistry and Li⁺ transport kinetics. Here, a structure-interface co-engineered microspherical Mo/W@Gr-Si anode is developed by integrating a flower-like graphene framework with Mo₂N/W₂C dual-phase heterostructures, enabling simultaneous regulation of Li⁺ adsorption and diffusion. Coupled density functional theory (DFT) calculations and advanced characterizations reveal a mechanism linking interfacial stabilization with Li⁺ transport, where the Mo₂N/W₂C heterophase stabilizes an inorganic-rich SEI and reduces diffusion barriers via electronic structure modulation. Consequently, the Mo/W@Gr-Si anode exhibits a low Li⁺ adsorption energy (-2.071 eV) and a reduced diffusion barrier (0.42 eV), delivering a high reversible capacity of 1821 mAh g^{- 1} at 0.1C with an initial coulombic efficiency of 88.12%, along with outstanding rate capability and cycling stability. Full cell paired with an NCM523 cathode retains 88.2% capacity after 300 cycles (0.5C), while pouch cells exhibit 84.6% retention after 200 cycles at 2C. This work offers a generalizable strategy for bridging interfacial stability and Li⁺ transport kinetics in high-performance silicon anodes.