l -Serine-Assisted Synthesis of Superparamagnetic Fe3O4Nanocubes for Lithuium Ion Batteries

Monodisperse superparamagnetic Fe 3 O 4 nanocubes with the edge length up to approximately 16 nm were synthesized by using a biomolecule-assisted solvothermal approach. The Fe 3 O 4 nanocubes are characterized by X-ray powder diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, and high-resolution transmission electron microscopy. The magnetic properties of the Fe 3 O 4 nanocubes are studied by zero-field cooling (ZFC) and field cooling (FC) procedures, i.e., M–T and M–H curves. The electrochemical behavior of the Fe 3 O 4 nanocubes was tested in lithium ion batteries, which presents high specific capacitance of 695.1 mA·h/g at a current rate of 0.2 C, higher than that of commonly used graphite electrode (372 mA·h/g), as well as excellent Coulombic efficiency of above 95% after the 11th cycle in the subsequent cycles.