Synthesis of core/shell spinel ferrite/carbon nanoparticles with enhanced cycling stability for lithium ion battery anodes

Monodispersed core/shell spinel ferrite/carbon nanoparticles are formed by thermolysis of metal (Fe ³⁺, Co ²⁺) oleates followed by carbon coating. The phase and morphology of nanoparticles are characterized by x-ray diffraction and transmission electron microscopy. Pure Fe ₃O ₄ and CoFe ₂O ₄ nanoparticles are initially prepared through thermal decomposition of metaloleate precursors at 310°C and they are found to exhibit poor electrochemical performance because of the easy aggregation of nanoparticles and the resulting increase in the interparticle contact resistance. In contrast, uniform carbon coating of Fe ₃O ₄ and CoFe ₂O ₄ nanoparticles by low-temperature (180°C) decomposition of malic acid allowed each nanoparticle to be electrically wired to a current collector through a conducting percolative path. Core/shell Fe ₃O ₄/C and CoFe ₂O ₄/C nanocomposite electrodes show a high specific capacity that can exceed 700mAhg ¹ after 200 cycles, along with enhanced cycling stability.