Designing hierarchical D-SiOx@NC/C@CNTs/rGO composites via thermal disproportionation and interfacial reconstruction for high-performance lithium-ion batteries

Silicon suboxides (SiO x ) are promising anodes for lithium-ion batteries, but their practical application is hindered by severe volume fluctuation and sluggish (de)lithiation kinetics. Herein, a hierarchical disproportionated-SiO x -based composite, D-SiO x @NC/C@CNTs/rGO-2, consisting of disproportionated SiO x (D-SiO x ) with in situ generated Si/SiO 2 domains, a nitrogen-doped carbon/carbon (NC/C) interphase, and an interconnected CNTs/rGO conductive framework, is constructed through thermal disproportionation, interphase engineering, and multidimensional conductive-network design. Thermal disproportionation induces the in situ formation of Si domains embedded in a SiO 2 buffering matrix, in which Si provides lithium-storage activity while SiO 2 alleviates volume variation and enhances structural stability. Meanwhile, a conformal nitrogen-doped carbon interphase mitigates chemo-mechanical stress and stabilizes the active interface, and the intertwined CNTs/rGO framework builds an efficient conductive network. As a result, the optimized anode delivers a reversible capacity of 876.4 mAh·g −1 after 500 cycles at 0.5 A g −1 , with a capacity retention of 83.7%, while electrode swelling is suppressed to ≈52% versus ≈159% for bare D-SiO x . Operando electrochemical impedance spectroscopy combined with distribution of relaxation times reveals reduced interfacial polarization and faster apparent Li  +  transport. A pre-lithiated LFP||D-SiO x @NC/C@CNTs/rGO-2 full cell also shows an initial Coulombic efficiency of 96.15% and stable cycling over 200 cycles.