Spray-pyrolyzed silicon/disordered carbon nanocomposites for lithium-ion battery anodes

A new and effective approach to prepare carbon-coated Si nanocomposites as high capacity anode materials for lithium-ion batteries with markedly improved electrochemical performance is described. Initially, nanosized Si particles (<100 nm) were mixed with different concentrations of the carbon source precursor, citric acid in ethanol solution via ultrasonication. Spray pyrolysis of these mixtures at 400 °C in air resulted in an amorphous carbon coating on the spherical Si nanoparticles. High-resolution transmission electron microscopy (HRTEM) analysis confirms a homogeneous layer of amorphous carbon coating of ∼10 nm. These resultant nanocomposites show excellent cycling performance, especially when the disordered carbon (DC) content is above 50 wt.%. The 44Si/56DC nanocomposite shows the highest specific capacity retention of 1120 mAh g⁻¹ after 100 cycles. The carbon-coating on the nanocrystalline Si particles appears to be the main reason for the good cyclability, suggesting the excellent potential of these Si/DC-based nanocomposites for use as alternative anodes for lithium-ion batteries.