Yolk-shell silicon/carbon composites prepared from aluminum-silicon alloy as anode materials for lithium-ion batteries

Silicon is an attractive anode material for lithium-ion batteries due to its ultrahigh theoretical specific capacity. However, its commercial application is largely limited by the poor cycling stability due to its huge volume change during lithiation and delithiation. A low-cost method is developed to prepare yolk-shell silicon@void@carbon composite particles in this study. The synthetic phenol-formaldehyde resole resin was used to bind the graphite to the surfaces of the aluminum-silicon alloy particles, and then was thermal cross-linked and carbonized; aluminum was gently dissolved into ferric chloride etchant, leaving void space between the carbon shell and silicon core. Owing to the presence of the robust carbon shell and internal void space, the yolk-shell composites exhibited significantly better cycling stability than the powder mixture of silicon and graphite. The capacity retention of the silicon component in the powder mixture dropped below 60% after only one cycle, whereas silicon in the composite still has about 70% remaining capacity after 100 cycles.