Triethoxysilane-derived SiOx-assisted structural reinforcement of Si/carbon nanotube composite for lithium-ion battery

Abstract

Herein, triethoxysilane-derived SiO_x is used as a robust adhesive anchor to bind Si nanoparticles (NPs) and carbon nanotubes (CNTs) to prepare a structurally reinforced Si/CNT microsphere composite. The chemical reaction between the silanol groups of triethoxysilane with the hydroxyl groups on the Si surface and acid-treated CNTs induce strong chemical bonds between the Si NPs and CNTs and among neighboring CNTs, facilitating electron-conduction pathways and structural integrity of the composite, even under severe stress/strain. Thus, the structurally reinforced Si/CNT/SiO_x microsphere composite exhibits superior cyclability: ∼88% of its initial capacity of 1112 mA h g⁻¹ is retained after 100 cycles at 0.5 A g⁻¹. Moreover, the Si/CNT/SiO_x composite exhibits a negligible change in electrode thickness after 100 cycles. The stable electrochemical behavior and negligible change in the electrode thickness are attributed to the maintenance of the electron-conduction pathways and structural integrity of the Si/CNT/SiO_x composite, enabled by the binding of neighboring CNTs with the SiO_x anchor.