Sn87Co13 alloys are prepared by two different reduction methods and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and electrochemical cycling. One method, using NaBH4 as a reducing agent, obtains aggregated particles with particle sizes from 20 to 200nm. The second method, using sodium naphthalenide as a reducing agent, shows a well-dispersed nanoalloy coated with amorphous carbon, with a particle size of 15nm. Although electrochemical results shows that the charge capacity of the two alloys is quite similar, 662mAh/g, the capacity retention of the nanoalloy prepared using sodium naphthalenide was 427mAh/g, which is two times higher after 30 cycles than the bulk analogue obtained using NaBH4. This is due to the uniform particle size and amorphous carbon layer that effectively reduces anisotropic volume expansion and also minimizes particle aggregation and pulverization that causes a direct electrical disconnection with the copper current collector.