Regulating Charge/Ion Transfer Kinetic Behavior Via Embedded Tiox in Hierarchical Tiox/Siox@C with Optimal Expansion Stress for Lithium Storage

The charge/ion transfer and structural stability of silicon suboxide (SiOX) for lithium-ion batteries (LIBs) are plaguing. Titanate oxide (TiO2) shows zero strain and high ion diffusion for lithiation, promising for improving its electrochemical properties. Herein, hybrid TiOX/SiOX@C (local reduction of TiO2 for TiOX) was prepared via magnesiothermic reaction and self-assembled as hierarchical microspheres. The embedded TiOX and hierarchical structures buffer the volume-expansion-induced strain of TiOX/SiOX@C for high structural integrity. Oxygen-vacancy sites around Ti and Si atoms for charge transfer tunnel and the heterostructure for fast interfacial charge response improve its electronic conductivity. The introduction of locally reduced Ti atoms alters oxygen structural dispersion, further reducing Li diffusion barriers. Even, the inevitable crack of TiOX/SiOX induces its exposure to the electrolyte, facilitating a compact solid electrolyte interphase layer for stable electrochemical performance. Thus, its open-circuit voltage curve displays a low lithiation platform due to its low polarization for Si-based anodes. These synergetic findings deliver the optimal TiOX/SiOX@C with high cycling stability (951.6 mAh g−1 at 1A g−1 after 1000 cycles with a capacity retention of ∼87.7%) and superb rate capability (516.5 mAh g−1 at 4 A g−1). This work provides a deep understanding of charge/ion kinetics for SiOX-based anodes of LIBs.