Free-Standing Si/Graphene Paper Using Si Nanoparticles Synthesized by Acid-Etching Al-Si Alloy Powder for High-Stability Li-Ion Battery Anodes

Abstract

Developing scalable, simple and low-cost synthesis approach for Si nanoparticles and fabricating Si/carbon composites with specific microstructure to improve the Li storage ability are of great significance for practical application of Si-based Li-ion battery anode. In this report, we employed a facile method to synthesize Si nanoparticles via acid-etching Al-Si alloy powder. The etching process was fully investigated. The as-synthesized Si nanoparticles (⿼10nm) were further embedded into graphene sheets to form a flexible, free-standing paper with ⿿sandwich-like⿿ structure. The Si/graphene paper was directly applied as anode for Li-ion batteries without adding any binder and conductive additive. The graphene sheets not only increase the conductivity of Si material, but also function as a flexible scaffold for strains/stresses release and volume expansion during charge/discharge cycling process, resulting in much higher cycling stability (1500mAhg⿿1 after 100 cycles at a current density of 100mAg⿿1 with Coulombic efficiency >99%) compared to the native Si nanoparticles. It provides a scalable Si nanoparticles synthesis approach and a promising high-performance Si/graphene anode material.