Fabrication of amorphous hollow mesoporous Si@SiOx nanoboxes as an anode material for enhanced lithium storage performance

Abstract

Hollow mesoporous Si@SiO_x nanoboxes are synthesized successfully by a simple sol–gel reaction of triethoxysilane using Fe₂O₃ nanocubes as the template, followed by a thermal reduction process under reducing atmosphere and subsequent acid treatment process. The as-prepared HM-Si/SiO_x nanoboxes exhibit a typical hollow structure with a uniform cavity size of ∼200 nm and ultrathin shells of ∼50 nm, in which the shell is composed of a large number of small particles (<10 nm). The results reveal that hollow mesoporous Si@SiO_x nanoboxes have sufficient internal nanovoids and a rationally designed mesoporous structure, which effectively buffers the volume variation of Si nanocrystals without fracture and maintains the structural integrity of the electrode during the cycling processes. The resulting hollow mesoporous Si@SiO_x nanobox electrode has a high initial reversible specific capacity of 940.29 mA h g⁻¹ at a current density of 200 mA g⁻¹, exceptional cycling stability (remains at 947.54 mA h g⁻¹ following 500 cycles), and superior rate capabilities. This reasonable structure design and novel approach can be of visible significance for the development of new Si-based anode materials for lithium-ion batteries.