Al2O3-sheathed Si/Li2SiO3 nanocomposite anode materials for high-performance lithium-ion batteries

Abstract

Silicon monoxide (SiO)-based materials have garnered significant attention as one of the promising high-capacity Li-storage anode materials. However, their practical application in commercial lithium-ion batteries is hindered by their low initial Coulombic efficiency (ICE) and poor cycle stability. The prelithiation of SiO can increase the ICE but does not guarantee cycle performance improvement. To address the ICE and cycle performance issues, we propose a heterogeneous Al2O3@Al-Si/Li2SiO3 nanocomposite material obtained through a two-step reaction of SiO, LiH, and Al. Scanning transmission electron microscopy with energy-dispersive X-ray spectroscopy and laser-assisted atom probe tomography reveal a heterogeneous structure consisting of an Al2O3 sheath and inner Si/Li2SiO3 nanocomposite, with a concentration gradient between them. The resulting Al2O3@Al-Si/Li2SiO3 nanocomposite material exhibits a high ICE of up to 89% and capacity retention of 72.8% after 200 cycles. The high structural stability induced by the core-sheath architecture plays a critical role in mitigating volume expansion and enhancing cycle performance.