Exceptional effect of benzene in uniform carbon coating of SiO _x nanocomposite for high-performance Li-ion batteries

A novel SiO _x @C composite is designed that uses benzene for both the homogenous dispersion of the Si source and simultaneous fabrication of a multiple carbon matrix on the composite. The overall morphology of the SiO _x @C composite and uniformly carbon-coated Si nanoparticles are verified using transmission electron microscopies with elemental mapping. This benzene-based synthesis process results in exceptional electrochemical properties for SiO _x . At a current density of 0.5 A g ⁻¹ , the SiO _x @C composite delivers a discharge capacity of 591 mAh g ⁻¹ with 99% coulombic efficiency over 600 cycles. Furthermore, the SiO _x @C composite exhibits outstanding power capability with a capacity of 602 mAh g ⁻¹ at a current density of 2 A g ⁻¹ , corresponding to ∼68% of that measured at 0.1 A g ⁻¹ . In contrast, the capacity of pristine SiO _x is extremely degraded under similar conditions.