Magnesium silicide-derived porous Sb-Si-C composite for stable lithium storage

Abstract

Porous Sb-Si-C composite materials were synthesized through two-step high-energy mechanical milling (HEMM) and chemical etching processes as an anode material for lithium secondary batteries. Sb2O3 and Mg2Si as starting materials were transformed into Sb, Si, and MgO phases after the first step of HEMM. Activated carbon was then incorporated into the composites during the second step of the milling. Finally, porous composites were synthesized by removing MgO through chemical etching. The prepared samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy, electron microscopy, and Brunauer–Emmett–Teller (BET) surface area measurement. The electrochemical lithiation and delithiation mechanism of the porous Sb-Si-C nanocomposite electrode was examined by using ex situ XRD analysis. Electrochemical test results demonstrated that the reversible capacity of approximately 450 mAh g−1 was maintained well after 200 cycles. This performance can be attributed to the porous structure and the amorphous carbon matrix for alleviation of volume changes during repeated Li+ insertion and extraction cycling.