Toward Mechanically Stable Silicon-Based Anodes Using Si/SiO x@C Hierarchical Structures with Well-Controlled Internal Buffer Voids.

Abstract

Low conductivity and structural degradation of silicon-based anodes lead to severe capacity fading, which fundamentally hinders their practical application in Li-ion batteries. Here, we report a scalable Si/SiO x@C anode architecture, which is constructed simultaneously by sintering a mixture of SiO/sucrose in argon atmosphere, followed by acid etching. The obtained structure features highly uniform Si nanocrystals embedded in silica matrices with well-controlled internal nanovoids, with all of them embraced by carbon shells. Because of the improvement of the volumetric efficiency for accommodating Si active spices and electrical properties, this hierarchical anode design enables the promising electrochemical performance, including a high initial reversible capacity (1210 mAh g-1), stable cycling performance (90% capacity retention after 100 cycles), and good rate capability (850 mAh g-1 at 2.0 A g-1 rate). More notably, the compact heterostructures derived from micro-SiO allow high active mass loading for practical applications and the facile and scalable fabrication strategy makes this electrode material potentially viable for commercialization in Li-ion batteries.