High-capacity lithium-storage materials in metal composite form are being extensively researched, which can replace the carbon-based lithium intercalation materials currently commercialized as the negative electrode of lithium rechargeable batteries. Herein, Sn nanocrystals and Sn nanocrystal/carbon composites with various particle sizes are prepared by the chemical reduction method where surfactant can control the resultant particle size because the particle size of metal-based materials is the main underlying factor for their electrochemical enhancement. The chemical reduction approach using surfactants is very effective for varying the particle size of Sn nanocrystals. Sn nanocrystals with the optimized particle size in terms of anodic properties are made into a composite with carbon acting as an agglomeration preventer as well as an electronic conductor. The controlled size of the Sn nanocrystal in the carbon is associated with their drastically improved electrochemical performance retaining above 65% of the initial capacity after 30 cycles.