Enhanced Cycle Stability of Magnetite/Carbon Nanoparticles for Li Ion Battery Electrodes

We demonstrate a facile synthesis of monodisperse magnetite ( Fe 3 O 4 ) nanoparticles (NPs) via a simple wet chemical route at 180°C using oleylamine ( C 18 H 37 N ), which serves as a solvent, ligand, and surfactant. The particles have a narrow size distribution centered at about 10 nm. To provide better electron conductivity and structural stability, the as‐synthesized particles are given a carbon nanocoating by pyrolysis of the residual surfactant on their surface. This pyrolysis forms a uniform thin nanocoating on each particle, and a core/shell Fe 3 O 4 /carbon NP network was thus obtained. The core/shell Fe 3 O 4 /carbon electrode shows better reversible capacity, cycle life, and rate capability than a bare Fe 3 O 4 NP electrode because of its efficient electron transport and stress relaxation provided by the thin carbon layer.