Oxygen-tailoring in SiOX/C with a covalent interface for high-performance lithium storage

Abstract

Oxygen-tailoring in silicon suboxide (SiO_X) can relieve its volume variation for highly structural integrity and form a stable solid electrolyte interface (SEI) layer. Herein, we propose the preparation of hierarchical SiO_X/C with different oxygen contents and interfacially covalent Si–O–C bonds for advanced lithium ion batteries (LIBs). Oxygen-manipulating projects are performed to adjust the oxygen content in SiO_X for low volume expansion (mechanical stress), in agreement with our experiment, stress distribution simulations and density functional theory analysis. The covalent Si–O–C bonds in metastable SiO_X/C are constructed to enhance the adsorption of ethylene carbonate for a stable SEI layer and re-assemble the electrical field for fast interfacial charge responses. These synthetic advantages in hierarchical SiO_X/C are beneficial for the structural integrity and the construction of a stable SEI layer. Prepared SiO_X/C exhibits excellent electrochemical performance in terms of cyclic stability (1010.4 mA h g⁻¹ after 300 cycles at 1 A g⁻¹), highly stable coulombic efficiency and rate capability (413.6 mA h g⁻¹ at 4 A g⁻¹). The work based on oxygen-manipulating projects and interfacial covalent bonds provides deep insights into the preparation of durable SiO_X-based anodes with a long lifespan and stable coulombic efficiency.