A General, One-Step and Template-Free Route to Rattle-Type Hollow Carbon Spheres and Their Application in Lithium Battery Anodes

摘要

A general, rapid, template-free, one-step, and continuous approach have been designed to rattle-type hollow carbon spheres (M@carbon, M - multiple Sn, Pt, Ag, or Fe-FeO nanoparticles) via ultrasonic spray pyrolysis of aqueous solutions containing sodium citrate and corresponding inorganic metal salts. The route involves the following three procedures: (1) initial generation of metal nanoparticles via the reduction of corresponding metal salts with sodium citrate in the hot liquid droplets and subsequent formation of a sodium citrate outer shell due to the tendency of free sodium citrate molecules to move to the periphery of the hot liquid droplets; (2) the formation of carbon outer shell via carbonization of the sodium citrate outer shell; and (3) the production of M@carbon via removing water-soluble byproduct. The content of encapsulated nanoparticles in M@carbon can be controlled via tuning the concentration of metal salts. Due to its novel structures, Sn@carbon exhibits high capacity and good cycle performance when they were used as anode materials for lithium batteries.