SiOx as a Potential Anode Material for Li-Ion Batteries: Role of Carbon Coating, Doping, and Structural Modifications

Abstract

Despite the high energy density of SiO x , its practical use as an anode material for Li-ion batteries is hindered by its low electronic conductivity and sluggish electron transport kinetics. These disadvantageous properties result from the insulating nature of SiO 2 , which leads to electrical contact loss and poor cyclability. Herein, we synthesized a C-SiO x composite based on amorphous carbon and a SiO x matrix via the alcoholysis reaction between SiCl 4 and ethylene glycol. We then used nonpolar benzene to simultaneously achieve homogenous dispersion of the Si source and the formation of a carbon coating layer, resulting in the formation of a (C-SiO x )@C composite with exceptional electrochemical properties. Next, we performed structural modifications using Ti doping and a multiple-carbon matrix to successfully fabricate a (C-Ti x Si 1 − x O y )@C composite. The combination of Ti doping and carbon coating greatly enhanced the conductivity of SiO x ; moreover, the incorporated carbon acted as an effective oxide buffer, preventing structural degradation. The (C-Ti x Si 1 − x O y )@C composite exhibited excellent capacity retention of 88.9% over 600 cycles at 1 A g − 1 with a capacity of 828 mAh g − 1 .