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 (SiO X) for lithium-ion batteries (LIBs) are plaguing. Titanate oxide (TiO 2) shows zero strain and high ion diffusion for lithiation, promising for improving its electrochemical properties. Herein, hybrid TiO X /SiO X @C (local reduction of TiO 2 for TiO X) was prepared via magnesiothermic reaction and self-assembled as hierarchical microspheres. The embedded TiO X and hierarchical structures buffer the volume-expansion-induced strain of TiO X /SiO X @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 TiO X /SiO X 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 TiO X /SiO X @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 SiO X -based anodes of LIBs. [Display omitted] • Ti is found to assist the reduction of TiO X /SiO X with a high crystalline Si phase. • Oxygen-vacancy TiO X improves the ion/charge kinetics of the electrodes. • TiO X phase is zero strain upon lithiation, stabilizing its cycling structure. • The covalent interface is beneficial to form a stable SEI layer. • TiO X /SiO X @C delivers a specific capacity of 951.6mAh/g at 1A/g after 1000 cycles. [ABSTRACT FROM AUTHOR]